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Cover page
The PEARL model

What is new in FOCUS PEARL 4.4.4?

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


How to use this help file?
Using the Help file

If you press the Help button on one of the forms, you will get information about a particular form (context sensitive help). You can also press the F1 button on the keyboard. Links will guide you to:

•	The theory.

•	Guidelines on model parameterisation.

•	Related forms.

•	References.

The Help file has, however, a lot more possibilities. You can use the buttons on top of the help window to navigate more efficiently.

•	Use the Contents button to get a table of contents.

•	Use the Index to search a topic.

•	Use the Back button to go to the previous topic.

•	Use the Print button to print a topic.

•	Use the Browse buttons of the help system (<< and >>) to browse through the help-file as if it where a printed book.

•	Use the Get Started button to go to the Get Started topic

•	Use the Support button to get information about support.

•	Use the Cover page button to jump to the Cover page

•	Use the Tree view button to display a tree of the PEARL user interface.

•	Use the Theory button to enter the Theory section of the Help file.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


About FOCUS PEARL version 4.4.4
About FOCUS PEARL

The PEARL model is used to evaluate the leaching of pesticide to the groundwater in support to the Dutch and European pesticide registration procedures. PEARL is an acronym for Pesticide Emission Assessment at Regional and Local scales. The model describes the fate of a pesticide and relevant transformation products in the soil-plant system.  The model supports the target quantities and scenarios set-up by the FOrum for the Co-ordination of pesticide fate models and their USe, FOCUS). The current FOCUS PEARL version is 4.4.4.

Authors

PEARL is a joint product of Alterra, the National Institute of Public Health and the Environment (RIVM) and the Netherlands Environmental Assessment Agency (PBL). The authors of the model are (alphabetically) Erik van den Berg (Alterra), Jos Boesten (Alterra), Daniel van Kraalingen (Alterra), Minze Leistra (Alterra), Ton van der Linden (RIVM) and Aaldrik Tiktak (PBL).

The model has replaced the former PESTLA and PESTRAS models since September 1, 2000. These two models will not be supported from September 1, 2000.

Model uses

Getting started

Processes

Overview of the system

Overview of the PEARL database

The main form of the PEARL user interface

Support and manuals

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


What is new in FOCUS PEARL 4.4.4?

FOCUS PEARL version 4.4.4 is fully compatible with FOCUS PEARL version 3.3.3. There will be no loss of data in your database created by FOCUS PEARL 3.3.3, as FOCUS PEARL 4.4.4 will upgrade your database when you open it for the first time with FOCUS PEARL 4.4.4.

FOCUS PEARL version 4.4.4 contains the revised FOCUS groundwater scenarios. There are a number of changes in these groundwater scenarios:

•	the procedure for assessing the irrigation amounts has been revised completely

•	the potential evapotranspiration of the southern scenarios has changed

•	rooting depths of all crops have been limited to 1 m

•	the course of time of the crop factors of all crops has changed

•	pH-H2O values of the soil layers have been included in the database

•	the 80th percentile in time is now calculated as the average of periods 16 and 17 (before period 17 was used)

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Model uses

•	First-tier of European pesticide registration procedures (model supports the target quantities and scenarios set-up by the Forum for International Co-ordination of pesticide fate models and their Use, FOCUS). See also Getting Started.

•	Higher-tier assessments (lysimeter and field studies).

•	Policy evaluation, particularly sustainable crop protection (Duurzame gewasbescherming).

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Registration

If you have downloaded PEARL from the JRC website (JRC website), you do not have the benefits of a registered PEARL user. We therefore strongly recommend you to register at the PEARL website. Registered users have some benefits over non-registered users:

•	You will receive the full version of the PEARL package, including the program PEARLNEQ

•	You can download the source code of the model

•	You will be put on the PEARL mailing list. Through the mailing list, we will inform you about updates, known bugs and reports.

To get direct support from the PEARL team, you must register at the PEARL website, even if you have downloaded from the JRC website.

Read also the License agreement and disclaimer

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Licence agreement

This License is a legal agreement between you, the individual or entity that is installing and/or using the SOFTWARE, and Alterra, as part of the private company with limited liability Alterra B.V., the National Institute of Public Health and the Environment (RIVM) and the Netherlands Environmental Assessment Agency (PBL); Alterra, RIVM and PBL are hereafter referred to as 'the owners'.

The user declares to have read the conditions of the license agreement accompanying the SOFTWARE [PEARL] and by installing agrees to abide by those conditions.

Permitted use and restrictions

Disclaimer of warranty on the SOFTWARE

Limitation of liability

Termination

Entire Agreement

Governing Law

Permitted use and restrictions

This License permits you to install and use the SOFTWARE on any of your computers at any one time for the purpose of conducting scientific research. You may copy the SOFTWARE for your own use. Except as expressly provided for in this License, you may not:

-	use, copy, decompile, reverse engineer, disassemble, modify or adapt the SOFTWARE, in whole or in part;

-	create derivative works based upon the SOFTWARE in whole or part;

-	remove any proprietary notices, labels or marks on the SOFTWARE;

-	rent, lease, loan, sublicense, distribute or otherwise transfer the SOFTWARE in any form to any third party.

When publishing research results that have been accomplished through the use of the SOFTWARE, you shall explicitly acknowledge the use of the SOFTWARE in your publication.

Disclaimer of warranty on the SOFTWARE

The SOFTWARE is intended for scientific use and has been developed with great care. However, the SOFTWARE may contain errors or inaccuracies that could cause failures or loss of data, and may be incomplete. You are encouraged to report any found bugs, but the owners shall have no obligation to remedy them. You expressly acknowledge and agree that the entire risk as to the applicability, quality, and performance of the SOFTWARE and all costs relating to defects are on you, not the owners. The SOFTWARE is provided "AS IS" without warranty of any kind. The owners expressly disclaim all warranties, express or implied, including, but not limited to, implied warranties of merchantability and fitness for a particular purpose and noninfringement of third party rights.

Limitation of liability

The owners shall not be liable for any damages or losses including direct, indirect, special, incidental or consequential damages or loss of profits to you arising out of the use of, results of the use of, or inability to use the SOFTWARE, whether based on breach of contract, tort( including negligence), product liability, or otherwise, and whether or not the owners have been advised of the possibility of such damages or losses. In no event shall the owners' liability under this License exceed the amount of the fee paid by you for this License.

Termination

This License is effective until terminated. You may terminate it by destroying all copies of the SOFTWARE. If you fail to comply with any term(s) of this License, this License will terminate automatically, without notice from the owners, and the owners will be entitled to pursue all available legal and equitable remedies to protect their interests. Upon such termination, you agree to destroy all copies of the SOFTWARE. All disclaimers of warranties and limitation of liability set forth in this License shall survive any termination of this License.

Entire Agreement

This License is the entire agreement. If any provision of this License is held invalid, the remainder of this License shall continue in full force and effect.

Governing Law

This License shall be governed by the laws of The Netherlands.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Tree view of the PEARL User Interface
The PEARL User Interface

PEARL uses a relational database for data storage. This database has the same hierarchy as the User Interface. Click on the diagram to go to one of the forms of the system.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Main form

The main form is the opening screen of PEARL and will serve as the control panel. You will enter the database in the last saved project.

Refer to Getting Started to learn about using one of the standard scenarios.

Browse Runs

Edit Run

The tabs of the Edit Run box

The Scenario box

The Pesticide box

The Menu

The main button bar

Graphs and reports

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Overview of screen functions

All forms of the PEARL user interface have a similar set-up. The substances form is taken as an example. Click on different parts of the diagram to learn about the general structure of the forms.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Overview of processes
Processes

The figure gives an overview of the processes included in PEARL. Click on a word to learn about processes included in PEARL. A comprehensive description of the process descriptions can be found in the manuals. You can also scroll through the process descriptions with the browse buttons in the Help window.

PEARL is a one-dimensional, dynamic, multi-layer model. The model describes the fate of a pesticide and relevant transformation products in the soil-plant system. The model is linked with the Soil Water Atmosphere Plant (SWAP) model. Pesticides can enter the system by direct application or by atmospheric deposition. The application methods described in PEARL are spraying of pesticide on the soil surface, spraying on the crop canopy, incorporation of pesticide into the topsoil (e.g. by rototillage), and injection of pesticide into the topsoil. PEARL and SWAP describe the following processes: Transient state soil water flow, evapotranspiration, interception of water, water uptake by plant roots, evaporation of water from the soil surface, lateral discharge, heat flow, pesticide application, dissipation of pesticide from the crop canopy, convective and dispersive transport of pesticide in the liquid phase, diffusion of pesticide through the gas and liquid phases, equilibrium sorption and non-equilibrium sorption, first-order transformation kinetics, uptake of pesticide by plant roots, and volatilisation of pesticide at the soil surface.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Overview of the PEARL database
The PEARL database

PEARL uses a relational database for data storage. This guarantees optimal access to the data and avoids data-redundancy. Read this section to learn about the structure of the database - you will find that there is a hierarchy and that the structure of the Graphical User Interface is the same as the structure of the database. Refer to the user manual for background information.

The project level

The model-run level

Major building-blocks level

Scenarios

Substance data

Application schemes

Simulation control

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Overview of the system
System overview

The PEARL modelling system consists of the following components. Click on the diagram to access the components.

Background

The core of the model is driven by a Graphical User Interface (the PEARL user interface), which is available for Windows 95/98/NT/2000/XP. The figure shows the linkage between the individual components of PEARL. The actual linkage between the individual components is established through text and binary files (i.e. the components are loosely coupled).  The Graphical User Interface generates the input files for PEARL. SWAP input files are created by PEARL, so it is always guaranteed that both models use the same data. This is particularly important if the model is used independently from the GUI, which is the case when performing Monte Carlo simulations or inverse modelling exercises. Relevant outputs of SWAP are transferred to PEARL through a binary datafile. Summary model-outputs of PEARL are transferred to the database, where they can be retrieved and viewed by the user. Comprehensive model-outputs (e.g. vertical profiles and daily values) can be viewed with the graphical program XY, which is also driven by the PEARL user interface.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Introduction
Getting started

In the first tier of the European pesticide registration procedure, PEARL is used in combination with fixed scenarios. PEARL supports the target quantities and scenarios set-up by the FOCUS groundwater working group. All the scenarios are stored in the database, so it is easy to access them from the PEARL user interface.

First-tier of the European registration procedure: Generating FOCUS runs

In higher-tier assessments, PEARL is used in combination with field or lysimeter data. In this case, you may want to create a new soil-profile, a new crop-calendar and define the lower boundary conditions of the hydrological model. Follow the link to learn more about higher-tier assessments.

Using PEARL for higher-tier assessments

You have now learned one of the most important features of the PEARL User Interface: You must work bottom-up - First specify the building blocks of your system and then combine them to create the run. Have a look at the database structure and you will see that there is a logical hierarchy.

The Pearl database

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Getting started with FOCUS
Generating FOCUS runs

Running a FOCUS scenario is easy - Just follow the procedure in the diagram.

You have seen that you have to define a substance and an application scheme before you can run a scenario. More general, PEARL uses the concept of building blocks - You must always define these building blocks before you can create a new model run.

The FOCUS wizard

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Getting started with higher-tier assessments
Using PEARL for higher-tier assessments

During the second and higher tiers of the registration procedure, field studies and lysimeter experiments become important. During this stage, the model should can be used in combination with on-site measured data. This implies that you have to start from scratch. Click in the diagram to find out how.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The FOCUS wizard

The FOCUS wizard is used for generating one or more runs as prescribed by the FOCUS modelling working group (2000, 2009). It is accessible from the main form of the PEARL User Interface.

Read the following sections before using the FOCUS wizard:

Generating FOCUS runs

FOCUS Reports

In the FOCUS wizard, you can select existing building blocks only. Make sure that the Substance and Application Scheme have been added to the database.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Old Dutch registration summary reports
Reports for the old Dutch standard scenario

The old Dutch pesticide registration procedure used different target quantities. Moreover, one weather year was used, which was repeated. See Tiktak et al. (2000) for details.

The Dutch summary report starts with a header, which contains some general information about the run. Then the following information is given for each substance:

•	The most important substance properties

•	The maximum average substance concentration in the upper groundwater

•	The fraction of the dosage leached into the upper groundwater

•	The fraction of the dosage volatilized

•	The mass content of substance in the plough layer at 365 days after application

The procedure for the registration of plant protection products in the Netherlands has been changed. Target quantities, as given in this report, cannot be used in the new procedure. For more details on the revised procedure see the PEARL website.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Projects

The projects form can be accessed from the main form, by pressing the Project button.

Projects are a great way of organising your model runs. Two types of projects can be distinguished:

•	User-defined projects. A user could, for example, put all model runs dealing with a single lysimeter study in one project.

•	Automatically generated projects. Runs generated by the FOCUS wizard are put into one project.

The following actions can be carried out in the browse box:

•	Select an existing project: Move the cursor to the project and press OK

•	Add a new project: Press the + key of the navigator. Then:

-	Give the project an appropriate name.

-	Additional information about the project can be entered in the comments field.

-	Press OK.

•	Delete a project: Move the cursor to the project, press the - key of the navigator and press OK.

Refer to Getting Started to learn about using one of the standard scenarios.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Creating FOCUS projects
FOCUS wizard

The FOCUS wizard is used for generating one or more runs as prescribed by the FOCUS modelling working group (2000, 2009). It is accessible from the main form of the PEARL User Interface.

Read the following sections before using the FOCUS wizard:

Generating FOCUS runs

FOCUS Reports

In the FOCUS wizard, you can select existing building blocks only. Make sure that the Substance and Application Scheme have been added to the database.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Creating runs
Scenario tab of the main form

The model inputs are accessed through the scenario tab of the main form. PEARL uses a relational database for data storage. From the main-form, you can only make a choice between existing building-blocks through so-called combo-boxes. If you want to create a new building-block, always do this before creating a run. Use the browse button to the right of the combo-boxes for this purpose.

Scenario dependent:

The user must also specify the initial groundwater level.

Pesticide dependent:

Some screen elements may be disabled. This is the case if you have chosen one of the default scenarios in PEARL. You can, however, still view the underlying tables using the browse button to the right of each combo-box.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Simulation control

This section contains general control options of PEARL. General control options of SWAP should be introduced into the SWAP control tab.

The following parameters must be specified:

•	The time-domain for the simulation must be specified in the Start/Stop fields. The date format is dd/mm/yyyy. The following restrictions apply:

-	The Stop date must be later than the Start date.

-	The time-domain is fixed in the case of a FOCUS scenario. A FOCUS run always starts at 01/01/1901. It will stop 26 years later in the case of annual applications, 46 years later in the case of biennial applications and 66 years later in the case of triennial applications.

-	The Stop Date may be overruled by the Stop Criterion (see below).

•	The Stop Criterion (kg/ha) can be used as an alternative for the stop date. If the Stop Criterion is unequal to zero, the simulation will stop if:

-	The areic mass in the system has become less than the Stop Criterion

-	The time is later than the end time (see above).

The Stop criterion will be ignored if set to zero. Do not use the Stop Criterion in the case of repeated applications.

•	By checking the Repeat Weather and Irrigation box, you can instruct PEARL to use the weather and irrigation data of one year and repeat this weather pattern. This option is used for the old Dutch standard scenario, which repeats the weather data for 1980 each year.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Archiving runs
Archive runs

All PEARL data are stored in a relational database. To cummunicate with different users, it may be necessary to export the ASCII files, used by the PEARL model. This can be achieved through the Archive Runs dialog. The following files will be stored:

•	The PEARL input file (prl file)

•	The PEARL meteo file (met file)

•	The PEARL irrigation file (irr file)

•	The PEARL summary file (sum file)

•	The PEARL output file (out file)

•	The PEARL log file (log file)

The model should be run before the actual archive can be made.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Locations

The Locations form can be accessed from the scenario tab of the main form. The locations form consists of a browse box and an edit box. In the browse box, you can select, add, or delete existing locations.

From the locations form the user can access data that are usually considered spatially distributed. A location is a combination of:

a soil profile

a meteo station

a regional groundwater system (the lower boundary of the hydrological model)

a local groundwater system (lateral drainage)

These four main building blocks of a location are selected in corresponding combo-boxes.

You can only make a choice from existing building-blocks. Use the browse button to the right of the combo-box to edit or add building-blocks.

The following information must be entered in the locations form:

•	A unique code.

•	The name of the location.

•	The country.

•	The longitude. The longitude must be between -180 and 180; east is positive.

•	The latitude. The latitude must be between -90 and 90; north is positive.

•	The altitude (m). The altitude must be between -400 and 3000 m.

•	The maximum ponding depth (m). Its value must be between 0 and 1 m.

•	The boundary air layer thickness (m). Its value must be between 1E-6 and 1 m.

•	The long-term average annual temperature (deg C). This temperature is used as the initial lower-boundary condition of the heat-flow submodel. Its value must be between -10 and 40 dec C.

•	The soil profile.

•	The meteo station.

•	An option for the lower boundary condition of the hydrological model.

•	The local drainage system (drainage levels). This form can only be accessed if the Calculate lateral drainage box is checked.

Although crops are also spatially distributed, the crop calendar and the irrigation scheme are not used in the definition of a location. They are at a higher hierarchical level according to definitions by the Focus Soil Modelling Working group (1997). They must therefore directly be entered from the scenario tab of the main form.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Soil profiles

The soil profiles form can be accessed from the locations form. The soil profiles form consists of three parts:

Soil Profiles where you can browse and edit soil profiles. This is the upper part of the form.

•	The Soil Horizons where you can browse and edit the individual soil horizons. Also the vertical numerical discretization of the model must be provided here. In this form, only the thickness of the horizons is specified, the actual soil properties have to be specified in the soil building-blocks form, which is accessible from this form.

•	The Factors for the effect of depth on transformation and sorption are specified as a function of soil horizon in the "default factors for the effect of depth" box. Some substances, however, show different dependency on the effect of depth. In these cases, different factors can be specified in the "non default factors for the effect of depth" box.

-	The depth dependence of transformation is assumed to be a soil property. Its value is usually 1 in the uppermost soil horizon. Its range is 0 - 1. For other transformation parameters, click here. For guidance on this parameter, click here.

-	If the sorption coefficient depends on other soil constituents than the organic matter content, the user can select the option 'Kf, user defined' in the Freundlich sorption tab of the substance form. In this case, the depth dependence of the sorption coefficient must be specified here. Its value must be between 0 and 1.

Building a new soil profile.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Soil horizons
Soil profiles

The soil profiles box is part of the Soil Profiles form. In the Browse Soil Profiles box, you can select, add, or delete soil profiles, using the navigator.

The following parameters, that apply to the soil profile as a whole, must be provided in the Edit Soil Profiles box:

•	A unique code

•	The name of the soil profile

•	The type of function that PEARL will use for the calculation of the relative diffusion coefficient. Three types of functions are available. PEARL has default parameters for all functions available; if you want to change one of these parameters, please go to the "relative diffusion coefficient" form by pressing the bottom to the right of the combo box.

•	Parameter values for the selected function must be entered in the Relative diffusion coefficient form (use the browse button). If no information is available, use the Millington Quirk option with default parameters.

•	The parameter in the soil evaporation reduction function (cm(1/2)). Its value must be between 0 and 1. See further guidance.

•	The 'crop factor' for bare soil. Its value must be between 0.5 and 1.5.

•	An option for the bulk-density. The bulk density can be input for each soil building block by the user, or it can be calculated with a pedotransfer function.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Soil building blocks

In this form, you must enter the basic physical and chemical soil characteristics. The form can be accessed from the Soil profiles form. PEARL uses the concept of generic building blocks (Wösten et al., 1994) for these soil properties.

In the Browse Soil Building Block box, you can select, add, or delete soil building blocks, using the navigator. After entering a code, you have to introduce basic soil parameters and parameters of the Mualem-van Genuchten functions.

Basic soil parameters

Mualem-van Genuchten functions

Basic soil parameters

•	The textural distribution (kg/kg). Notice that the textural distribution refers to the mineral soil only, so the sum of the sand, silt and clay fractions must be one.

•	The mass content of organic matter (kg/kg). The mass content of organic matter refers to dry soil; its value must be between 0 and 1.

•	The pH. The pH is used for the sorption model of weak acids. As most sorption experiments are being carried out in 0.01 M CaCl2, the pH-CaCl2 is preferred. If the pH-CaCl2 is not available, the user should set the pH Correction variable in the Freundlich tab of the substances form unequal to zero. The pH must be between 1 and 13.

•	The dry bulk-density of the soil, Rho (kg/m3). The bulk density is only required if the option for the calculation of the bulk density in the soil profiles form was set to Input, otherwise it is calculated on the basis of the organic matter content. The bulk density must be between 100 and 2000 kg/m3.

Parameters of the Mualem-van Genuchten functions

Soil water flow is described with the Richards equation. The soil hydraulic properties are described with analytical functions. Parameter values of these functions must be provided in this form:

•	The saturated water content, ThetaSat or ès (m3/m3). Range is 0.05 - 0.95 m3/m3

•	The residual water content, ThetaRes or èr (m3/m3). Range is 0 - 0.4 m3/m3.

•	Parameter AlphaDry, notation ád (1/cm). Range is 0.001 - 1 (1/cm). See also below.

•	Parameter AlphaWet, notation áw (1/cm). Range is 0.001 - 1 (1/cm). See also below.

•	Parameter n (-). Range is 1 - 5.

•	The saturated hydraulic conductivity, KSat or Ks (m/d). Range is 0.0001 - 10 m/d.

•	Parameter Lambda or ë (-). Range is -25 until 25.

Parameter AlphaDry applies to the main drying curve of the retention curve, whereas AlphaWet applies to the main wetting curve. If the user does not simulate hysteresis, AlphaDry and AlphaWet may be equal. Hysteresis can be swithed on and off in the Swap control tab of the main form.

Soil profiles

The Richards equation

Parameter values for the Mualem-van Genuchten functions

Hysteresis

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Meteo stations

The Meteo Stations form can be accessed from the Locations form.

Contents of the Edit box

Importing data

Exporting data

Viewing data

Contents of the Edit box

In the edit box, the following information must be provided:

•	A unique code

•	The name of the meteo station

•	The country

•	The longitude. The longitude must be between -180 and 180; East is positive.

•	The latitude. The latitude must be between -90 and 90; North is positive.

•	The altitude (m). The altitude must be between -400 and 3000 m.

•	An option for the calculation of the potential evapotranspiration:

-	Input: The potential evapotranspiration is provided by the user.

-	Penman:The potential evapotranspiration is calculated with the Penman open water approach.

-	Makkink: The potential evapotranspiration is calculated with the Makkink approach.

•	The actual data must be imported using the 'import datafile' button.

Importing weather data

PEARL uses daily weather data, which can be imported using the Import DataFile button. The weather data file is an ASCII file existing of 11 space delimited columns. The name of the meteostation must be between single quotes. See the example. Depending on the evaporation option, some columns can be set to a no data value (e.g. -99.9).

Carefully check that the weather data file does not contain tabs.

Format of the weather data file

Example of a weather data file

Exporting weather data

Weather data are stored in the database. They can be exported using the Create datafile button.

A weather datafile is automatically generated if the model is run.

Viewing weather data

The data can be viewed and graphed, using the View button.

Details

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Regional groundwater system (Lower boundary conditions)
Lower boundary conditions

In this section, the lower boundary conditions of the hydrological model have to be specified. The Lower Boundary conditions form is accessible from the locations form.

PEARL makes a distinction between local drainage fluxes to ditches and field-drains and the seepage flux due to regional groundwater flow. The seepage flux due to regional groundwater flow is the lower boundary flux, the local drainage flux is treated as a sink term. See also the theory and the figure.

PEARL offers eight options for the lower boundary condition. The applicable option must be chosen in the locations form. Most options require additional input, which must be specified in the lower boundary conditions form. Depending on the option chosen, one of eight tabs will be active. The other tabs may be filled, but they are not used.

The following eight options are available (click on links for further information on parameter values):

•	The Pressure head lower boundary condition (Dirichlet condition).

•	Regional bottom flux specified as a function of time (Neuman condition). The annual variation is described with a sine function.

•	Regional bottom flux calculated using an empirical flux-groundwater level relationship (Flux boundary condition).

•	 The Free drainage of soil profile

•	The Groundwater level specified as a function of time.

•	Regional bottom flux is calculated using the hydraulic head difference between the phreatic groundwater and the groundwater in the semi-confined aquifer (Cauchy condition).

•	The Lysimeter boundary condition

•	The Zero flux boundary condition

The initial groundwater level must be set in the Simulation control tab of the main form.

Theory on lower boundary conditions

Locations

Lateral drainage to ditches and field-drains

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Local groundwater system (Drainage levels)
Drainage levels

In this section, the local drainage fluxes to ditches and field-drains have to be specified. The Drainage Levels form is accessible from the locations form. Before entering the drainage levels form, you must check the Calculate Drainage Levels box in the Locations form.

PEARL makes a distinction between local drainage fluxes to ditches and field-drains and the seepage flux due to regional groundwater flow. The seepage flux due to regional groundwater flow is the lower boundary flux, the local drainage flux is treated as a sink term. See also the theory and the figure.

You can enter a drainage level with the + button of the navigator. Up to five local drainage level systems can be specified. For each drainage level, the following parameters must be provided:

•	Drainage level sequence number. The sequence number must be unique and number from 1 to 5.

•	The drainage resistance (d). Its value must be between 10 and 1E5 d.

•	The infiltration resistance (d). Its value must be between 10 and 1E5 d.

•	The distance (m) between the drainage systems. The range is 1 to 1000 m.

•	The depth of the bottom of the drainage system (m). Its value must be between 0 and 10 m.

•	The drainage system type, which can be a field-drain or an open channel.

Warning: If the option for the Lower Boundary condition is set to Flux boundary condition, the calculated bottom flux includes local drainage to surface waters and drains, so local drainage must not be used in combination with this option.

Theory

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Crop calendar
Crop Calendars

The Crop Calendars form can be accessed from the scenario tab of the main form.

The Crop Calendars form consists of two parts:

•	 Crop Calenars where you can browse and edit the crop calendar (upper part).

•	 Crops where you can browse and edit the individual crops (lower part). Also the emergence and harvest dates must be provided here.

-	The Crop Stages form is accessible from the crops box. Click here for a definition of crop stages.

Guidance on building a new crop calendar

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Crops

The Crops form can be accessed from the Crop Calendars form. PEARL uses two types of crop properties:

•	Dynamic crop properties, such as the Leaf Area Index. These properties are input as a function of development stage.

•	Static crop properties.

The dynamic crop properties must be entered in the Crop Stages form, which can be accessed from the Crop Calendar form.

In the Crops form, you have to introduce the static crop properties:

•	A unique code.

•	The name of the crop.

•	Critical pressure heads of the root water extraction function:

-	The anaerobiosis point, h1 (cm). Its value must be between -100 and 0 cm.

-	The reduction point at near-saturation, h2 (cm). Its value must be between -1000 and 0 cm.

-	Two reduction points in the dry range, i.e. one for high evaporative demands (h3l) and one for low evaporative demands (h3h). Their values should be between -10000 and 0 cm.

-	The wilting point (cm). Its value must be between -16000 and 0 cm.

-	If these values are available for pF values instead of pressure heads, they should be converted (i.e. h = -10pF). Click here for a table of critical pressure heads for common crops.

•	The extinction coefficient for global solar radiation. Its value must be between 0 and 2. See also the theory.

•	The minimum canopy resistance (s/m). Its value must be between 0 and 1000 s/m. The minimum canopy resistance is only required if the Penman-Monteith equation is used.

•	The constant in the equation for interception of water by the crop canopy (cm). Its value must be between 0 and 1.

•	Critical pressure head for irrigation. Irrigation is applied if the pressure head at a certain depth in the root zone drops below this value. By using this option, the soil water content will be brought back to field capacity. This figure is only used if the irrigation option in the irrigation schedule form has been set to "Sprinkler irrigation, irrigation depth calculated by the model" or "Surface irrigation, irrigation depth calculated by the model".

•	Depth of virtual tensiometer. Depth at which the critical pressure head for irrigation is evaluated. Only relevant if the irrigation option in the irrigation schedule form has been set to "Sprinkler irrigation, irrigation depth calculated by the model" or "Surface irrigation, irrigation depth calculated by the model".

•	If the Crop Cycle option in the Crop Calendars form is set to Variable, the course of the development stage with time will be controlled by the temperature sum. The advantage of this option is that regional differentiation of crop growth can be made on the basis air temperature. The following temperature sums must be given:

-	The temperature sum at emergence (development stage 0). Its value must be between -10 and 20 deg C.

-	The temperature sum from emergence (development stage 0) to anthesis (development stage 0.5). Its value must be between 0 and 10000 deg C.

-	The temperature sum from anthesis (development stage 0.5) to maturity (development stage 1). Its value must be between 0 and 10000 deg C.

-	If the Crop Cycle option is set to Fixed, these three parameters can be ignored.

•	The relative root density distribution must be entered in the root density form, which can be accessed by pressing the 'Root density' button.

Crop calendar form

Crops

Root density distribution

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Crops stages
Crop stages

In this form, you must specify the dynamic crop properties (i.e. crop properties that are dependent on time). PEARL uses the concept of development stages for describing the time-dependence.

The following parameters must be specified for each development stage:

•	The Leaf Area Index (m2/m2). The Leaf Area Index must be between 0 and 12 m2/m2.

•	Empirical crop factors (-) must be provided if the potential evapotranspiration is calculated according to the Makkink approach. The crop factor is in the range 0.5 - 1.5. The option for the potential evapotranspiration must be set in the Meteo Stations form.

•	The rooting depth (m). The rooting depth must be in the range 0-10 m. It is further limited by the depth of the soil profile in the Soil Profiles form. The relative root length distribution must be specified in the Crops form.

•	If the potential evapotranspiration is calculated according to the Penman-Monteith approach, PEARL needs information on the crop height (m). The crop height must have a value between 0 and 10 m.

A maximum number of 36 crop stages can be defined.

The crops form

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Irrigation
Irrigation schemes

The Irrigation Schemes form can be accessed from the scenario tab of the main form. The irrigation form consists of two parts:

•	The left-hand side of the form, where you can browse and edit the irrigation scheme.

•	The right-hand side of the form, where you can browse and edit individual irrigation events. Notice that this side of the form is not visible if you have selected 'no irrigation'.

To create an irrigation scheme, do the following:

•	First, create the irrigation scheme:

-	Press + in the navigator in the irrigation scheme box.

-	Enter a unique Code in the edit box.

-	Enter a description.

-	Enter the irrigation type.

•	Sprinkler irrigation. If a crop is present, interception of water and canopy processes will be simulated.

•	Surface irrigation. In this case, the water is directly applied to the soil surface and canopy processes will not be simulated.

•	Sprinkler irrigation, irrigation depth calculated by the model. Irrigation is applied whenever the pressure head drops below a prescribed threshold value. These threshold values are crop specific and must be introduced into the crops form.  If a crop is present, interception of water and canopy processes will be simulated.

•	Surface irrigation, irrigation depth calculated by the model. Irrigation is applied whenever the pressure head drops below a prescribed threshold value. These threshold values are crop specific and must be introduced into the crops form.  In this case, the water is directly applied to the soil surface and canopy processes will not be simulated.

•	If the irrigation type has been set to "Sprinkler irrigation" of "Surface irrigation", irrigation events must be specified by the user. The following two methods can be followed:

-	Through the user interface:

•	Press + in the navigator in the irrigation events box

•	Enter the date. The date must be entered as dd/mm/yyyy.

•	Enter the irrigation depth (mm). The depth must be greater than zero.

•	Repeat until done

-	By importing a datafile. Carefully read the instructions on file format before importing.

•	Press Close to confirm the changes.

If the irrigation option has been set to "Sprinkler irrigation, irrigation depth calculated by the model" or "Surface irrigation, irrigation depth calculated by the model" it is not necessary to supply irrigation events.

Editing scenarios

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Deposition

Substances can enter the system through wet or dry deposition. Deposition schemes can be added in the Deposition Schemes form, which can be accessed from the scenario tab of the main form. The deposition form consists of two parts:

•	The left-hand side of the form, where you can browse and edit the deposition scheme.

•	The right-hand side of the form, where you can browse and edit deposition record. Notice that this side of the form is not visible if you have selected 'no deposition'.

If a crop is present, substances will be deposited on the crop canopy in proportion to the soil cover, which implies that crop processes are simulated.

To create a new deposition scheme, do the following:

•	First, create the deposition scheme:

-	Press + in the navigator in the deposition scheme box.

-	Enter a unique Code in the edit box.

-	Enter a description.

•	Now, add deposition records:

-	Press + in the navigator in the deposition events box

-	Enter the date. The date must be entered as dd/mm/yyyy.

-	Enter the flux of substance in deposition (kg ha-1 d-1). The flux of substance in deposition must be >= 0.

-	Repeat until done

•	Press Close to confirm the changes.

Substances can also enter the system in irrigation water. The substance concentration in irrigation water must be entered in the scenario tab of the main form.

Editing scenarios

Crop processes

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Repeat interval for applications

The repeat interval for applications combo-box at the scenario tab of the main form can be used to repeat entire application and tillage schemes. The following options are available:

•	NoRepeat	The application and tillage schemes will not be repeated.

•	1 	The application and tillage schemes will be repeated annually

•	2 	The application and tillage schemes will be repeated biennially

•	3 	The application and tillage schemes will be repeated triennially.

The repeat interval for applications applies to the entire annual application scheme and not to individual applications. If you want to simulate repeated applications within-the-year, you must specify multiple applications in the applications form.

When using one of the FOCUS scenarios, the length of the simulation is based on the repeat interval of applications (FOCUS soil modelling Working group, 1997):

•	26 years in the case of annual applications.

•	46 years in the case of biennial applications.

•	66 years in the case of triennial applications.

Editing scenarios

Application schemes

Tillage schemes

Generating FOCUS scenarios

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Application schemes
Applications schemes

Use this form to edit application schemes. The application schemes form can be accessed from the scenario tab of the main form.

The annual application schedule can be repeated annually, biennially or triennially. You can also decide not to repeat the application schedule. The repeat option must be selected in the 'repeat interval for applications' combo-box of the main form.

The application schemes form consists of two halves:

•	The application schemes to the left. Here, you can browse and edit the schemes

•	The applications to the right. Here, you can browse and edit the individual applications.

The main form

Repeat interval for applications

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Application events
Applications

The applications box is part of the Application Schemes form. In the browse box, you can select, add, or delete applications. The Applications box has two tabs, i.e. one tab for entering absolute applications and one tab for entering relative applications.

Absolute and relative applications may be mixed in one application scheme.

To add a new application to an application scheme, act as follows:

•	Press + at the navigator

•	Choose between relative and absolute applications.

•	In the case of an absolute application, enter the date in the date-field

•	In the case of a relative application, enter the following information:

-	Select between harvest or emergence

-	Enter the number of days before or after crop emergence or crop harvest. Negative numbers denote before, positive numbers denote after.

•	Enter the application type in the Type box. PEARL can simulate the following five types of applications :

-	Application to the canopy; fraction of substance intercepted user specified

-	Application to the canopy; fraction of substance intercepted calculated on the basis of the soil coverage fraction

-	Application to the soil surface

-	Injection

-	Incorporation

•	Enter the dosage (kg/ha) in the dosage field. The dosage must be greater than zero.

•	Depending on the application type, you must further specify:

-	The injection depth (m) in the case of injection. The depth must be greater than zero.

-	The incorporation depth (m) in the case of incorporation. The depth must be greater than zero.

-	The fraction of substance intercepted by the canopy (-) in the case of an application to the canopy. The fraction must be between 0 and 1.

•	Press Close when ready

Background information

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Tillage schemes
Tillage

The Tillage form can be accessed from the scenario tab of the main form. The tillage form consists of two parts:

•	In the left-hand side of the form, you can browse and edit the tillage scheme.

•	In the right-hand side of the form, you can browse and edit the individual tillage events. Notice that this side of the form is not visible if you have selected 'no tillage'.

To create a tillage scheme, do the following:

•	First, create the tillage scheme:

-	Press + in the navigator in the tillage scheme box.

-	Enter a unique Code in the edit box.

-	Enter a description.

•	Now, add tillage events:

-	Press + in the navigator in the tillage events box

-	Enter the date. The date must be entered as dd/mm/yyyy.

-	Enter the tillage depth (m). The depth must be greater than zero.

-	Repeat until done

•	Press Close to confirm the changes.

The entire tillage scheme will be repeated if the Repeat Interval of Applications has been set to 1, 2 or 3.

Editing scenarios

Repeat interval of applications and tillage schemes

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Substances

Use this form to edit substance properties. The substances form can be accessed from the scenario tab of the main form. Like all other forms, the substances screen contains a browse box and an edit box.

PEARL can simulate the fate of a parent substance and its transformation products (metabolites) in soil. The substance which is applied or deposited must be the parent. You can make a substance a parent substance by checking the 'parent' check box in the general tab.

You have to specify the following substance properties:

•	Properties of the individual substances

•	The transformation scheme

It is not necessary to enter a transformation scheme if you do want not simulate transformation products.

Edit scenarios

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


General substance properties

Often, the general pesticide properties can be taken from a handbook on chemical properties of pesticides. The general substance properties are used for the calculation of the Henry coefficient.

•	A unique code must be introduced into the code field. The maximum length of the code is five alpha-numerical characters.

•	The name of the substance can be introduced in the name field.

•	The parent checkbox must be used to distinguish between parent substances (i.e. substances that are applied or deposited) and transformation products.

•	The molar mass (g/mol) must be between 10 and 10,000

•	The saturated vapour pressure (Pa) must be between 0 and 200,000.

•	The molar enthalpy of vaporisation (kJ/mol) must be between 0 and 200

•	The solubility in water (mg/L) must be between 0 and 1000,000.

•	The molar enthalpy of dissolution (kJ/mol) must be between -200 and 200

The saturated vapour pressure and the solubility in water are temperature dependent. They must be accompanied by the temperature reflecting the experimental conditions.

Transport in the gas phase

Editing substances

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Freundlich sorption

PEARL considers three phases in soil: solid phase, liquid phase and gas phase. Further, the soil is divided into an equilibrium-domain and a non-equilibrium domain. In this tab, all parameters dealing with sorption must be provided. The sorption of pesticides is described with a Freundlich type equation.

We recommend to derive the Freundlich equilibrium parameters from standardized slurry experiments in which soil-water suspensions are equilibrated for about one day (OECD Guideline 106).

The Freundlich tab consists of three parts:

•	Parameters describing the Freundlich coefficient

•	The reference concentration and the Freundlich exponent

•	Non-equilibrium sorption parameters

The Freundlich equation

The coefficient for sorption on organic matter

Theory on pH dependent sorption

Equilibrium and non-equilibrium domains

Editing substance properties

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Transformation

PEARL uses a first-order rate equation for substance transformation. In this tab, parameters that affect the transformation rate must be specified:

•	The transformation half-life time (d). The half-life time must be greater than 1.

Guidance

•	The temperature reflecting the experimental conditions during the incubation study (deg C). The temperature must be between 5 and 30 deg C.

Guidance

•	The optimum moisture conditions check box. If checked, PEARL will assume that the incubation study has been carried out under optimum moisture conditions. Optimum moisture conditions are conditions of field capacity or wetter (i.e. wetter than pF 2).

-	If the experiment has NOT been carried out under optimum moisture conditions, or if this is not sure, the moisture content (kg/kg) during the incubation study must be specified. Its value must be between 0.01 and 1.

Guidance

•	The molar enthalpy of transformation (kJ/mol). Its value must be between 0 and 200. The molar enthalpy of transformation is necessary in the Arrhenius function.

Guidance

•	The effect of soil moisture on the rate coefficient is described with an equation proposed by Walker. This equation requires an exponent (exponent for the effect of liquid).

Guidance

•	The effect of depth on transformation rate is assumed to be a soil property and must be introduced in the soil horizons box of the soils form.

In the case of pesticides that show sorption/desorption kinetics, a different procedure should be used to obtain the transformation half-life.

Editing substances

First-order rate transformation

Temperature dependence of the half-life time

Moisture dependence of the half-life time

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Diffusion

In this tab, the reference diffusion coefficients must be specified:

•	The reference diffusion coefficient of pesticide in pure water (m2/d). Its value must be between 1E-5 and 3E-4 m2/d.

Guidance

•	The reference diffusion coefficient of pesticide in air (m2/d). Its value must be between 0.1 and 3 m2/d.

Guidance

•	The reference temperature (deg C) at wich the diffusion coefficients were measured or estimated, which must be between 10 and 30. Only one reference temperature can be specified, which applies to both the diffusion coefficient in air and the diffusion coefficient in pure water.

The diffusion coefficient of pesticide in the soil phases is also affected by the relative diffusion coefficient function. Parameter values for this function must be specified in the soil profiles form.

Editing substances

Relative diffusion coefficients

Transport in the liquid phase.

Transport in the gas phase.

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Crop interactions

The following two groups of model parameters must be specified here:

•	Parameters dealing with canopy processes

•	Parameters dealing with uptake of pesticides by plant roots

Canopy processes

Canopy processes are simulated if:

•	The pesticide is applied to the canopy

•	The deposition is simulated

•	a pesticide is added via sprinkler irrigation.

Canopy processes are irrelevant for transformation products.

Processes that occur in the plant canopy are volatilization, penetration into the plants and (photochemical) transformation (see the theory). The following parameters are relevant:

•	The canopy processes option, which can be set to 'lumped' or 'specified'. The default option is 'lumped'.

•	If the canopy processes option is set to lumped, the user must specify:

-	The overall dissipation half-life time (d). Its value must be between 1 and 1E6.

•	If the canopy processes option set to 'specified', the following three half-lives must be given:

-	The half-life (d) due to penetration.

-	The half-life (d) due to volatilisation.

-	The half-life (d) due to (photochemical) transformation.

All half-life times must be between 1 and 1E6 d.

•	The wash-off factor of pesticides (1/m). Its value must be between 1e-6 and 100 m-1.

Editing substances

Theory on canopy processes

Uptake by plant roots

The uptake of pesticides by plant roots is described by an equation, which one parameter only:

•	The empirical transpiration stream concentration factor, which must be between 0 and 10.

Editing substances

Theory on uptake by plant roots

Guidance

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Transformation schemes

The transformation scheme form can be accessed from the substances form, using the 'transformation scheme' button. The derivation of transformation fractions from incubation studies is not unambiguous. Therefore, we strongly advise to read the Guidance on deriving transformation fractions before proceeding.

The properties of all substances (both the parent substance and the metabolites) must be entered in the substances form before building the transformation scheme.

To build a transformation scheme, do the following:

•	Enter the transformation schemes form.

•	The left part of the form shows the parent product and some of its main properties. You cannot edit this part of the screen.

•	To the right you see the browse metabolites box. To add a transformation product, do the following:

-	Press the + button on the navigator

-	Select an existing substance using the to substance combo-box.

-	Enter the transformation fraction in the fraction transformed field. This fraction is usually smaller than 1, but exceptions occur.

•	Repeat the previous step for all transformation products of the first generation.

•	Repeat all previous steps for higher generation metabolites. A substance of a lower generation must be chosen as the parent compound in the substance form.

By default, PEARL will not simulate any metabolites.

Editing substances

Guidance on deriving transformation fractions

Example

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Introduction
Detailed description of the PEARL input file

The PEARL input file contains the following sections:

Nr	Section name	Kind of model parameters
1	Simulation control	Simulation options
2	Soil profile and soil properties	Soil profile, soil properties
3	Weather and irrigation data	File names for weather and irrigation data
4	Boundary conditions of hydrological model	Lower boundary flux and drainage/infiltration parameters
5	Compound properties	Compound properties
6	Management	Application and tillage
7	Initial and boundary conditions	Initial pesticide concentration and deposition
8	Crop section	Crop calendar and crop properties
9	Output control	Input/output options

Listing of the PEARL input file

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Simulation control

Time domain

Additional stop criterion

Control of the hydrological model SWAP

Accuracy of the hydrological model SWAP

Listing

Time-domain

The time-domain for the simulation is specified with the variables TimStart and TimEnd. The date must be specified in the format dd-mmm-yyyy. Please notice that the time-domain is fixed in the case of running FOCUS scenarios and the old Dutch standard scenario. According to guidelines of the FOCUS soil modeling Working group (1997), FOCUS simulations must start at 01-Jan-1901. The length of the run should be 26 years in the case of annual applications, 46 years in the case of biennial applications and 66 years in the case of triennial applications. The time-domain for the old Dutch standard scenario is 01-Jan-1980 until 31-Dec-2000.

Listing

Additional stop criterion.

The variable AmaSysEnd can be used as an additional stop criterion. The simulations will stop if the areic mass of pesticide in the soil system has become less than AmaSysEnd. This variable will be ignored if set to zero.

Listing

Control of the hydrological model SWAP.

The other variables in the control section control the hydrological model swap. The RepeatHydrology option can be used to repeat weather and irrigation data. If set to Yes, weather and irrigation data of one year are constantly repeated. This option is intended to be used in combination with the old Dutch standard scenario, which repeats weather data from the year 1980. The hydrology option (OptHyd) determines how PEARL calls the hydrological model swap. The following options are availabe:

•	OffLine: PEARL assumes that swap has already been run. A hydrological datafile (RunId.pfo) must be prepared in advance.

•	OnLine: PEARL generates the input files for swap and runs swap.

•	Automatic: PEARL checks if the hydrological datafile (RunId.pfo) is already available. In this case, the hydrological calculations will be skipped.

•	Only: The hydrological model is run, but the rest of the simulations is skipped. This switch is interesting for users who want to test or calibrate the hydrological model, without (already) running the pesticide part. Output is written in PEARL format.

•	GenerateInput: PEARL creates input for the hydrological model only.

Listing

Accuracy of the hydrological model.

The variables DelTimSwaMin and DelTimSwaMax determine the minimum and maximum time-steps in the swap model. The model will look for the optimal time step between the preset limits. Making the time-step too large could lead to instability, while making it too small will increase the computation time substantially. The stop criterion for the iteration procedure (ThetaTol) defines the accuracy of the simulations. Choosing it too large could introduce a numerical water balance error.

Listing

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Soil profile and soil properties

The soil profile

Basic soil properties

Soil physical properties

Ponding and air boundary layer

Soil evaporation parameters

Parameter values of the functions describing the relative diffusion coefficients

Dispersion length

Listing

The soil profile

The vertical discretization is input through the SoilProfile table. For each soil horizon, the thickness of the horizon, and the number of soil layers used in the finite-difference scheme must be provided. The maximum number of soil horizons is currently set to 10, the maximum number of numerical soil layers is set to 500. The number of soil layers is a compromise between accuracy and computation time. Computation time increases approximately with the square of the number of soil layers. On the other hand, predictions may become inaccurate if the layer thickness is taken too large. This is particularly true if the expected concentration in the groundwater is lower than 0.001 μg/L (Leistra et al., 2000). For most simulations, however, a layer-thickness of 2.5 cm in the top 30 cm, 5 cm in the 0.3-1 m soil layer and 10 cm in the layer below 1 m is fair compromise.

Listing

Basic soil properties

Basic soil properties are input in the SoilProperties table. For each soil horizon, the textural distribution (FraSand, FraSilt and FraClay), the mass content of organic matter (CntOm) and the pH have to be specified. Notice that the textural distribution refers to the mineral soil only, so the sum of the sand, silt and clay fractions should be one. The mass content of organic matter refers to dry soil. The pH is used for the sorption model of weak acids. As most sorption experiments are being carried out in 0.01 M CaCl2, the pH-CaCl2 is preferred. If the pH-CaCl2 is not available, the user should set the pHCorrection variable unequal to zero.

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Soil physical properties

Parameters of the Van Genuchten functions are input in the VanGenuchtenPar table.

The columns should contain θs (ThetaSat), θr (ThetaRes), α (Alpha), n (n), Ks (KSat) and λ (l). If the bulk-density is unknown, it can be calculated by the model (OptRho). If set to Calculate, the model uses the pedo-transfer function (Bollen et al., 1995):

where ρb (kg m3) is the dry bulk density and mom (kg kg1) is mass content of organic matter. If OptRho is set to Input, the bulk density should be provided in table Rho.

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Ponding and air boundary layer.

The maximum ponding layer thickness (ZPndMax) determines the maximum thickness of the water layer that can be present on the soil profile before surface runoff starts. The thickness of the air boundary layer must be specified in the ThiAirBouLay record.

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Soil evaporation parameters

The potential evaporation can be corrected by a factor FacEvpSol. This is particularly important in the case of a small soil cover fraction, because the equation for partitioning the potential evaporation has been derived for situations where the canopy shades the ground. FacEvpSol can be given a value between 0.5 and 1.5. The actual soil evaporation rate is calculated using hydraulic properties and an empirical reduction function. Parameter â in this relationship must be provided in the CofRedEvp record.

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Parameter values of the functions describing the relative diffusion coefficients

The diffusion of compounds is affected by the diffusion coefficient in water and air and by the relative diffusion coefficient. The diffusion coefficients are compound properties, the relative diffusion coefficients are soil properties. Three functions can be used for the relative diffusion coefficient, i.e. the functions published by Millington and Quirk, Currie, and Troeh et al.. The value of the option OptCofDifRel determines which of the three functions is used by the model. The following parameters should further be specified:

•	If OptCofDifRel is set to MillingtonQuirk: aM (ExpDifLiqMilNom) and bM (ExpDifLiq-MilDen) for diffusion in the liquid phase; ExpDifGasMilNom and ExpDifGasMilDen for diffusion in the gas phase.

•	If OptCofDifRel is set to Currie: aC (CofDifLiqCur) and bC (ExpDifLiqCur) for diffusion in the liquid phase; CofDifGasCur and ExpDifGasCur for diffusion in the gas phase.

•	If OptCofDifRel is set to Troeh: aT (CofDifLiqTro) and bT (ExpDifLiqTro) for diffusion in the liquid phase; CofDifGasTro and ExpDifGasTro for diffusion in the gas phase.

Parameterization

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Dispersion length

The dispersion length, Ldis,L should be given for each soil horizon (table LenDisLiq). Please notice that the distance between the nodal points, Δz, should be small enough to meet the Peclet condition; i.e. the dispersion length must be greater than 0.5 X the distance between two nodal points

Guidance on dispersion length

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© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Weather and irrigation data

In this section, the names of the files with weather and irrigation data should be specified. This section further contains some options.

Weather

Irrigation

Soil temperature

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Weather data

The name of the file with weather data should be specified in the MeteoStation record. The altitude (Alt) and latitude (Lat) are also required. The name should be given without the extension, and has a maximum length of eight alphanumerical characters. PEARL automatically adds the extension .met to the file name, so in the above listed example the full name is debilt.met. PEARL needs some additional information. First, the user should specify which method is chosen for the computation of the potential evapotranspiration (OptEvp). Three options are available: (i) the potential evapotranspiration is input by the model, (ii) the Penman-Monteith equation is used, and (iii) the Makkink equation is used. If Penman-Monteith is selected, solar radiation, minimum and maximum air temperature, air humidity, wind speed and precipitation are required. If Makkink is selected, only minimum and maximum air temperature, solar radiation and precipitation are necessary.

Format of the file with weather data

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Soil temperatures

To calculate the initial soil temperature profile, PEARL requires the temperature at the lower boundary (TemLboSta). If measured data are unavailable, we recommend the use of the long-term average air-temperature.

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Irrigation

The name of the file with weather data should be specified in the IrrigationData record. The name should be given without the extension, and has a maximum length of eight alphanumerical characters. PEARL automatically adds the extension .irr to the file name, so in the above listed example the full name is debilt.irr. Irrigation water can be added to the crop canopy (Sprinkler irrigation) or to the soil surface (Surface irrigation). The type of irrigation should be specified in the OptIrr record.

Format of the file with irrigation data

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© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Compound properties

In this section, the properties of all compound must be specified. In this section, the identifier names are concatenated with compound names (in this example 'pest').

Compound table

Reaction scheme

Transformation rate parameters

Freundlich equilibrium sorption

Non-equilibrium sorption

Gas-liquid partitioning

Pesticide uptake

Diffusion coefficients

Pesticide fate at the crop canopy

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Compound table

The compounds section starts with the list of compound codes (the Compounds table). The maximum length of each code is five letters. For each compound, the molar mass (MolMas) must be specified.

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Reaction scheme

The reaction scheme (see figure and guidance) is input in the FraPrtDau table. For each parent compound j, the molar fraction of compound transformed into daughter i must be specified. The input file contains examples for one and three compounds.

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Transformation rate parameters

This section contains the variables that affect the transformation rate of the compound. The transformation half-life time (DT50Ref) must be specified together with the temperature reflecting the experimental conditions during the incubation study (TemRefTra). Then, the user must specify whether the experiments have been carried out under optimum moisture conditions (i.e. wetter than pF 2). Record OptCntLiqTraRef can be used for this purpose, its value is Optimum or NonOptimum. If set to NonOptimum, PEARL needs information about the moisture content during the incubation study (CntLiqTraRef). The temperature dependence of transformation is described with an Arrhenius equation; the molar activation energy is input in record MolEntTra. The effect of soil water on the rate coefficient is described according to Walker. The exponent in this equation should be specified in record ExpLiqTra. The effect of depth on transformation rate must be introduced in the FacZTra table. Click here for further information on transformation parameters.

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Freundlich equilibrium sorption

The sorption of compounds is described with a Freundlich equation. The value of the reference concentration must be introduced in the ConLiqRef record. Its value must be within the concentration range of the simulation study. The default value is 1 mg L-1.

Three methods are available to describe the Freundlich coefficient; the desired approach must be specified in the OptCofFre record. The most common approach (OptCofFre is pH-independent) is to calculate the Freundlich coefficient from the organic matter content and the coefficient for sorption on organic matter. If OptCofFre is set to pH-dependent, the Freundlich coefficient is calculated with an equation for sorption of weak acids. In cases that the sorption of pesticides is not dependent on the organic matter content, the Freundlich coefficient can be introduced directly.  In these cases, OptCofFre should be set to CofFre.

In the most common approach (OptCofFre is pH-independent), only two parameters have to be introduced, i.e. the coefficient for sorption on organic matter, Kom,eq (KomEql) and n (ExpFre).

If OptCofFre is set to pH-dependent, two coefficients for sorption on organic matter must be specified, i.e. KomEqlAcid (Kom,eq,ac) and KomEqlBase (Kom,eq,ba). In addition, the negative logarithm of the  dissociation constant (pKa) and a pHCorrection are required.

If OptCofFre is set to CofFre, the user should specify the Freundlich coefficient measured in the top-soil (CofFre) and the factor to describe the depth dependence of sorption (FacZSor). The factor to describe the depth dependence of sorption should be 1 in the top-soil.

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Non-equilibrium sorption

PEARL requires two parameters for non-equilibrium sorption, i.e. the desorption rate coefficient, kd, and the factor describing the ratio KF,ne/KF,eq, where KF,ne is the Freundlich coefficient at the non-equilibrium site and KFe,eq is the Freundlich coefficient at the equilibrium site (FacSorNeqEql).

The desorption rate coefficient should be specified in the CofRatDes record. Please notice that non-equilibrium sorption will not be simulated if CofRatDes is set equal to zero.

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Gas-liquid partitioning

The gas-liquid phase partitioning coefficient is affected by compound properties that can be taken from a handbook on chemical properties of pesticides (e.g. Tomlin, 1994, Hornsby et al., 1996). PEARL needs the saturated vapor pressure (PreVapRef), the temperature at which this parameter is determined (TemRefVap), the enthalpy of vaporization MolEntVap, the solubility of pesticide (SlbWatRef), the temperature at which the water solubility is obtained (TemRefSlb) and the molar enthalpy of dissolution (MolEntSlb).

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Pesticide uptake

The only parameter in the equation for uptake of pesticides is the coefficient for the uptake by plant roots, FacUpt.

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Diffusion coefficients

The diffusion coefficients of pesticides in pure water (CofDifWatRef) and air (CofDifAirRef) are compound properties and must be specified in this section. Parameters for the relative diffusion coefficient are specified in the soil section. The diffusion coefficients are temperature dependent. The reference temperature should be introduced in record TemRefDif.

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Pesticide fate at the crop canopy

In the last part of the compound section, parameter values must be given for the submodel on pesticide fate at the crop canopy. In this submodel only the parent compound is considered, as the reaction scheme is derived for products formed in the soil. For this reason, the pesticide code should not be concatenated to the identifiers below.

Processes that occur at the plant canopy are volatilization, penetration into the plant and (photochemical) transformation. These processes are described with first-order rate reactions. The user can make a choice between a lumped description of the processes at the crop canopy, or a full description of dissipation (record OptDspCrp). If set to 'Specified', the user should specify the half-life due to penetration (DT50PenCrp), volatilization (DT50VolCrp) and transformation (DT50TraCrp). If set to 'Lumped'. an overall half-life (DT50DspCrp) is sufficient.

The wash-off of pesticides is described with a zero-order equation with one parameter (FacWasCrp).

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© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Application and tillage

Repeat interval of applications

Application table

Tillage table

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Repeat interval of applications

This section contains data on pesticide applications and tillage. First, a variable DelTimEvt  should be specified. This variable determines the repeat interval in years of the event table. If set to 2, for example, biennial applications are simulated. If set to NoRepeat, the application table will not be repeated.

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Application table

The actual applications are specified in the Applications table.

•	The first column in this table contains the application date. Normal date format can be used, but the year is only required if DelTimEvt has been set to NoRepeat. You can also use relative dates; i.e. a number of dates relative to harvest or crop emergence. The format is xx-Emg-+/-yyy where xx is the crop sequence number, and yyy is the number of days. For example, 01-Emg-10 implies that the pesticide is applied 10 days before emergence of crop 1.

•	The second column contains the application type, which must have one of the following values:

•	Application to the soil surface (AppSolSur).

•	Incorporation (AppSolTil). If this option is chosen, the user must specify the tillage depth in the third column.

•	Injection (AppSolInj). If this option is chosen, the user must specify the injection depth in the third column.

•	Application to the crop canopy; fraction intercepted user specified (AppCrpUsr). The interception fraction must be specified in column 3.

•	Application to the crop canopy; fraction intercepted calculated on the basis of the soil cover fraction (AppCrpLAI).

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Tillage table

Tillage events must be introduced into the TillageDates table. Column 1 contains the tillage date, column 2 contains the tillage depth. Please notice that the DelTimEvt switch operates on both the Applications and the TillageDates tables.

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© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Boundary and initial conditions of PEARL

Initial conditions

Upper boundary conditions

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Initial conditions

Both the mass content of pesticide in the equilibrium domain (CntSysEql) and the non-equilibrium domain of the soil system (CntSysNeq) should be specified in this section. The initial concentration is usually set to zero, i.e. the simulation starts with pesticide-free soil. Only in the case of previous pesticide applications, the initial pesticide concentration should be set unequal to zero. The intial mass content of metabolites cannot be specified.

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Upper boundary condition

The upper boundary of the system is the crop canopy. This implies that pesticide entering the soil by deposition is always subject to dissipation at the crop canopy. Deposition fluxes should be specified in the FlmDep table. Deposition fluxes are linearly interpolated between two dates, so in the case of a constant deposition rate only two dates need to be specified (see the example). If OptIrr is set to Sprlinkler, dissipation at the crop canopy will be calculated. Please notice that only one concentration can be specified, which applies to all irrigation events.

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© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Crop properties

This section contains the crop properties. PEARL uses a simple crop growth model, i.e. the relevant crop parameters have to be provided by the user as a function of development stage (see below). Notice that most identifiers in this section have been concatenated with crop names. In the example below, only one crop named 'Maize' is described.

Crop calendar

Course of development stage with time

Dynamic crop properties

Root density table

Crop water use

Light extinction and interception

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Crop calendar

The crop section starts with the crop calendar. The user should first specify whether the calendar must apply to all years (option RepeatCrops). Secondly, the actual crop calendar must be provided (table Crops). The crop calendar consists of three columns: (i) emergence (not seeding) date of crop, (ii) harvest date of crop, and (iii) crop name. A single crop can occur several times in the crop table, but the following restrictions apply: (i) the length of the growing season must constant, and (ii) a crop is linked to a single development stage table (see below). If the user wants the crop to have different development stages over the years, a unique crop name must be specified for each year, e.g. Maize80, Maize81, etc. During periods that no crop is present, the model will use parameter values for bare soil.

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Course of development stage with time

Dynamic crop properties, such as the Leaf Area Index and the rooting depth are input as a function of the development stage. The development stage is 0 at emergence, 0.5 at flowering (anthesis) and 1 at maturity (notice that in the original publication by Van Heemst (1986), the development stage is between 0 and 2.

The course of development stage with time can either be controlled by the temperature sum, or can be linear in time. One of these two options should be chosen with the switch OptLenCrp. If set to 'Fixed' (development stage linear with time) no additional parameters are required. If set to 'Variable',  the user should specify the temperature sum at emergence (TemSumSta), the temperature sum from emergence to anthesis (TemSumEmgAnt), and the temperature sum from anthesis to maturity (TemSumAntMat). The advantage of this option is that regional differentiation of crop growth can be made on the basis air temperature.

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Dynamic crop properties

The Leaf Area Index (LAI), crop factor (FacCrp), rooting depth (ZRoot) and crop height (HeightCrp) are input in table CrpPar. A maximum number of 36 rows can be entered in the table. One table must be provided for each crop considered.

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Root density table

The user may define up to 11 data pairs to define the relative root density distribution as a function of the relative rooting depth (table RootDensity). Any unit can be used, the model will normalize the root density distribution in such a way that the integral of root density times depth over the root zone equals one.

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Crop water use

The user must enter the pressure heads defining the root water extraction function. HLim1 is the anaerobiosis point, HLim2 is the reduction point at near-saturation, HLim3 is the reduction point at dry conditions, and HLim4 is the wilting point. If these values are available for pF values instead of pressure heads, they should be converted (i.e. h = -10pF).

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Light extinction and interception

PEARL needs the extinction coefficient of global solar radiation, Κ. The interception coefficient (CofIntCrp) controls the amount of interception by the crop canopy. In case of ordinary agricultural crops, a may be set to 0.25. If set to zero, no interception will be calculated (in fact PEARL will substitute a very small value in the SWAP files to prevent division by zero). Please notice that at high precipitation rates, the interception rate asymptotically reaches aLAI.

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© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Output control

Output as a function of time

Vertical profiles

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Output as a function of time

In this section, the daily output is controlled. The following steps must be followed:

•	First specify whether the daily output file should be saved (OptDelOutput). If set to Yes, the daily output file will be removed. This option saves time if summary information is required only.

•	Specify the desired (fixed) output interval (record DelTimPrn). If set to zero, PEARL will calculate the output interval based on the begin and end date of the simulation. It is important to realize that PEARL generates averages over the print interval and not point values. This implies that a larger print interval generates a smoother picture.

•	Specify whether fluxes should be cumulated over the entire simulation period (PrintCumulatives).

•	Specify the desired format of the date (DateFormat) and the actual values in the output file (OutputFormat). The DateFormat can be set to DaysFromSta (print the number of days since the start of the simulation), DaysFrom1900 (print the number of days since 1-Jan-1900) or Years (print the number of years since the start of the simulation). To specify the output format, normal fortran notation should be used (see the example in appendix 3).

•	Specify the depths for which output is requested (OutputDepths)

•	Specify for each variable whether output is wanted or not (print_)

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Output of vertical profiles

The user can specify a number of dates at which vertical profiles of the most important state variables are produced (table (VerticalProfiles).

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© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Boundary and initial conditions of the hydrological model

In this section, the boundary conditions of the hydrological model are specified. swap makes a distinction between the seepage flux due to regional groundwater flow and the local drainage flux to ditches and drains (see figure). The seepage flux due to regional groundwater flow is the lower boundary condition of the model, the local drainage flux is considered a sink term.

Initial conditions of the hydrological model

Lower boundary conditions

Lateral drainage

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Initial conditions

It is assumed that initally the pressure head of each nodal point is in hydrostatic equilibrium with the groundwater table. This implies that the pressure head at the groundwater table equals zero, and that the pressure head of each nodal point decreases linearly with height towards the soil surface. The user only needs to specify the initial depth of the groundwater table (ZGrwLevSta). If, however, OptLbo (see next paragraph) is set to GrwLev, the model uses the appropriate record in the GrwLev table.

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Lower boundary conditions

SWAP offers eight options for the lower boundary condition. The value of OptLbo determines which type of boundary condition is used by the model. The following options are available: (1) GrwLev, (2) Flux, (3) Head, (4) FncGrwLev, (5) Dirichlet, (6) ZeroFlux, (7) FreeDrain and (8) Lysimeter. For option 1-5, the user should specify additional information.

If OptLbo is set to GrwLev, the groundwater level should be specified as a function of time (table GrwLev). Normal data-format can be used. If RepeatHydrology is Yes, the year can be omitted.

If OptLbo is set to Flux, a sine function is applied to generate the daily regional bottom flux. The user should specify the mean (FlvLiqLboAvg) and amplitude (FlvLiqLboAmp) of the annual bottom flux. Also the date at which the maximum of the sine wave occurs should be given (DayFlvLiqLboMax). Notice that negative values denote downward fluxes and positive fluxes denote upward values.

If OptLbo is set to Head, the regional bottom flux is calculated using the head difference between the phreatic groundwater and the groundwater in the semi-confining aquifer (see figure). The average groundwater level in the field, Φavg, is affected by the drainage base (HeaDraBase) and by the shape of the groundwater table (OptShapeGrwLev), which can be Elliptic, Parabolic, Sinusoidal or NoDrains. The daily value of the hydraulic head in the semi-confining aquifer, Φaqf is described by a sine-wave. The user must specify its annual average value (HeaAqfAvg), the amplitude (HeaAqfAmp) and the date at which the maximum hydraulic head occurs (TimHeaAqfMax). The bottom flux is also affected by the vertical resistance of the aquitard (RstAqt, γaqt).

If OptLbo is set to FncGrwLev, the bottom flux is calculated as a function of the groundwater level. If this option is chosen, the model needs the coefficient (CofFncGrwLev) and the exponent (ExpFncGrwLev). Please realize that this option is only valid for deep, sandy areas. The calculated bottom flux includes local drainage to surface waters and drains, so local drainage should be set to zero if this option is used.

If OptLbo is set to Dirichlet, the pressure head at the lower boundary should be specified as a function of time (table h). Normal data-format can be used. If RepeatHydrology  is Yes, the year can be omitted.

The FreeDrain, Lysimeter and ZeroFlux options do not require additional input.

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Local drainage fluxes to ditches and drains

If OptLbo is set to GrwLev, Flux, Head, Dirichlet or ZeroFlux, a local drainage flux can be defined in addition to the regional seepage flux. The user must first specify if local drainage should be simulated (OptDra). Then the number of local drainage systems, such as drainage-tiles and field-ditches) must be provided (NumDraLev). swap can simulate up to 5 local drainage systems.

For each local drainage system, a drainage flux is calculated. The model needs information about the bottom of the drainage system (ZDra) and the drainage resistance (RstDra) . The procedure that distributes the drainage flux over the individual soil layers additionally requires information about the drainage type (DraTyp) and the distance between the drainage systems (DistDra). To distinguish between the local drainage systems, the sequence number of each local drainage system should be concatenated to the record identifiers specified above, so we get DraTyp_1, DraTyp_2, etc.

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© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Running the model with the PEARL GUI
Running the model

Once you have created a number of model runs, you can run the model. To run the model, first select one or more runs for execution. You can:

•	Double click on a run to select one run

•	Select al runs with the Runs Menu of the main form

•	Deselect all runs with the Runs Menu of the main form

Press the Calculate button to actually run the model.

•	All selected runs will be carried out.

•	The PEARL User Interface will write the input files and call the simulation kernel.

•	You can follow the course of the simulation.

The run status is displayed in two columns, i.e. the ResultsSummary and the ResultsDetailed column. These columns indicate whether a detailed output file and a summary output file are available. The status can be:

•	NotThere: Run has not yet been carried out, or the run has been edited.

•	There: Results are available for further processing.

•	Error: The run has generated an error message.

Errors can be reviewed in the Run Status tab of the main form.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Run status

This tab shows some log and error information. The information cannot be edited. For each run, the following information is shown:

•	The Run Id (a unique sequence number generated by the PEARL User Interface)

•	A field indicating whether a Summary output file is available. A Summary file must be there if you want to create predefined graphs.

•	A field indicating whether a Detailed output file is available. A detailed output file must be there if you want to create User defined graphs.

•	The Creation date.

•	The last Modification date.

•	Error messages.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Running the model from a DOS box

After you have installed the model, a copy of the pearl kernel will be available in the bin directory of the pearl package. Copies of the input file are availble in the defscen directory of the pearl package. These input files can be used as a basis for further processing. It is a good practice to copy all input files to a working directory. Do not edit the original files, so they can serve as a back-up. The defscen directory contains the following three files:

•	a general input file, defscen.prl

•	the file containing weather data, defscen.met

•	an optional file containing irrigation data, defscen.irr

You can change the name of the input files, but the extensions are fixed.

Assuming that you have installed pearl in the directory c:\Program Files\Pearl, you can start the model by typing:

"C:\program files\pearl\bin\pearlmodel" RunID

where RunID is the first part of the name of the general input file. If, for example, the name of the input file is 'atra.prl', you can start the pearl kernel by typing:

"C:\program files\pearl\bin\pearlmodel" atra

The Run ID has a maximum length of eight alphanumerical characters. Please notice that the quotes are obligatory, because the path contains a space. If you wish to run the model several times, it may be handy to create a batch file "pearl.bat", which contains the following two lines:

@echo off

"C:\program files\pearl\bin\pearlmodel" %1

If put in your working directory, the model can be run by typing pearl, followed by the RunID.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


General output options
Output control

In this tab, you can control the output to the following two files:

•	The detailed output file. This file contains all dynamic variables, such as state-variables and fluxes.

•	The summary output file. This file contains the annual balances and the report for the pesticide registration procedures.

The following variables control the detailed output file:

•	With the Detailed Output checkbox, you can switch off detailed output. This option will significantly speed-up the simulations, but you will only get summary output.

•	Use the Detailed Output options button to select variables for output.

•	The format of the time column in the detailed output file. PEARL can write Years, the number of days since the start of the simulation or the number of days since 1-1-1900. The second option is the default option; the third option can be used if you want to compare model runs with different start and end dates.

•	The print method. With this option, preset print time steps can be choosen, i.e. days, decades, months and years. Different print time steps can be choosen by setting the print method to other and specifying the print time step explicitly.

•	The print time step (d), which must be >= 0 days. This value is only used, if the print method is set to other. If set to zero, PEARL will create its print time step so that there will finally be 1000 datapairs available. This is sufficient for most graphs.

PEARL will always calculate averages over the print time step. Moreover, the time printed is in the middle of the print interval. Click here to see the effect.

•	The precision of the dependent variables ('reals') in the detailed output file. PEARL uses FORTRAN format specifiers.

•	If the Output Cumulative box is checked, fluxes will be printed cumulative.

The following variables control the Summary Output file.

•	The Summary Report combo-box controls the type of report:

-	Dutch registration report: Summary variables for the Dutch registration procedure will be printed.

-	FOCUS report. A FOCUS summary will be printed.

-	No report. No special report will be printed.

•	The depth of the FOCUS target layer (m). Use this variable to control:

-	The depth at which the 80th percentile of the leaching concentration is calculated

-	The depth for which water and mass balances are calculated.

The depth of the FOCUS layer must be > 0.1 m. Refer to the section on FOCUS reports.

Tip:

Use the following settings to reduce the size of the detailed output file (and thus computation time):

-  Choose a large print interval.

-  Choose a low precision.

-  Do not choose to many variables and depths for output.

Detailed Output Options

FOCUS reports

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Selecting variables for output
Detailed Output Options

The detailed output options form is accessible from the output control tab of the main form. This form consists of three parts:

•	In the upper part you can browse the categories of available variables.

•	In the lower-left part of the form you can browse the individual variables within a category

•	In the lower-right part of the form you can select and browse the intended output depths.

The available categories

PEARL has the following categories of output variables available:

•	Pearl Soil balance:

Mass balance of the soil system, which includes variables like the areic mass of transformation and the areic mass of pesticide in the soil system.

•	Pearl concentrations:

Concentration of pesticide in the various phases of the soil system, such as the substance concentration in the liquid phase.

•	Pearl Crop balance:

Mass balance of pesticide at the crop canopy

•	Pearl fluxes:

Mass fluxes of pesticides.

•	Pearl general:

Miscellaneous variables, such as the time-step.

•	Swap Soil fluxes:

Volume fluxes of water, such as the soil water flux

•	Swap general:

Miscellaneous variables, such as the groundwater level and the Leaf Area Index.

•	Swap states:

State variables of the hydrological model, such as the soil water content.

Variables available for output

In this part of the form, you can select variables for output. You can

•	Select and deselect variables individually by double clicking

•	Select and deselect groups of variables using the buttons.

-	Use the TOXSWA button to select all variables wanted by the TOXSWA model (Adriaanse et al., 2000).

-	Use the Clear All Variables button to deselect all variables

-	Use the Set All Variables button to select all variables for output. Remember, however, that this option will generate very large files and slow down the computations.

-	Use the Set Defaults button to revert to the default settings.

Intended depths

In the Depths combo box, you can choose between the following options:

•	None: No depth dependend output will be given

•	All: All depths will be output

•	Other: Output depths must be provided by the user. Add depths to the output file with the + button on the navigator. Use the - button to delete records.

We use the term Intended Depths, because the model will look for the nearest nodal point (see figure). This implies that the selected depth will not (always) correspond exactly with the final output depth. The exact depths will be given in the User Defined Graphs form.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Reports

PEARL reports give an overview of indicators of pesticide leaching, to be used in the pesticide registration process. PEARL has two kind of reports available:

•	A report for the first tier of the European pesticide registration procedure (FOCUS report).

•	A report for the first tier of the Old Dutch pesticide registration procedure.

If you use one of the standard scenarios, PEARL will automatically generate the appropriate report. In other cases, you have to specify the type of report in the output control tab.

You can access Reports with the Reports button on the main form.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


File Locations

All intermediate PEARL files are stored in the Database directory of your PEARL system. If, for example, you have installed PEARL in the directory c:\Program Files\Pearl, the PEARL files will be stored in c:\Program Files\Pearl\Database.

PEARL uses the Run ID to create the file names:

•	The PEARL input file has extension prl (e.g. 3.prl)

•	The detailed output file has extension out (e.g. 3.out)

•	The summary output file has extension sum (e.g. 3.sum)

•	The error file has extension err (e.g. 3.err).

All intermediate PEARL files are ASCII files, which can be copied to another directory and edited.

Example files with a full description, including ranges, can be found in the defscen directory.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Summary output

The summary output file contains the annual balances and the report for the pesticide registration procedures. The Summary output file can be accessed through the View menu of the main form.

The following information is given:

•	Annual water balances of the FOCUS target layer.

•	Annual water balance of the entire soil profile.

•	Annual mass balance of substance in the FOCUS target layer.

•	Annual mass balance of substance in the entire soil profile.

•	Annual mass balance of substance at the crop canopy.

The rest of the summary file is used for creating reports.

The summary output file is an ASCII file, which can be copied.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Detailed output

The detailed output file has extension .out (see File locations) and contains output at regular intervals. The Detailed output file can be accessed through the View menu of the main form.

Detailed output is controlled from the Output Control tab of the main form. The output file is stored in the IODir.

The detailed output file contains records of the following format:

Time   Date   Identifier   Value(1)   …  Value(n)

where n is:

•	one in the case of variables that have no depth

•	the number of intended depths specified in the output control tab.

The detailed output file is suppressed if the 'detailed output' checkbox is not checked.

Fluxes will be printed cumulative if you have checked the Cumulative checkbox.

Example

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Introduction
Graphs

PEARL has two kind of graphs available:

•	The Predefined graphs. A graphical representation of selected variables from the summary file, such as the annual balances.

•	The User defined graphs. A graphical representation of data from the detailed output file.

Graphs can only be created if the model has been run successfully.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Predefined graphs

Predefined graphs can be accessed with the Graphs, predefined button in the main form.

The model must be run before graphs can be made. To create predefined graphs, the ResultsSummary column in the browse box of the main form must be 'there'.

The following five graphs are available:

•	The annual mass balance of the substance in the soil system and in the FOCUS target layer. The following mass balance terms (kg/ha) are shown:

-	Net inputs to the system: annual substance application, annual deposition and annual substance formation

-	Annual mass change

-	Net outputs from the system: Annual substance transformation, annual substance discharge by lateral drainage, annual substance leaching, annual substance uptake and annual substance volatilisation.

•	The annual water balance of the soil system and of the FOCUS target layer. The following water balance terms (mm) are shown:

-	Net inputs to the system: annual precipitation and irrigation

-	The annual change in water storage

-	Net outputs from the system: annual seepage, annual soil evaporation, annual transpiration, annual interception and annual run-off.

•	The FOCUS summary graph. This graph shows the following information for the 20 FOCUS periods:

-	The substance concentration in the water leaching from the FOCUS target layer. The arrow indicates the 80th percentile of the leaching concentration.

-	The mass leached from the FOCUS target layer.

-	The water percolated from the FOCUS target layer.

-	The frequency distribution of the leaching concentration. The frequency distribution is created using the 20 FOCUS periods. The 80th percentile of the leaching concentration is shown explicitly by a horizontal line.

Graphs, User defined

Output control

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


User defined graphs

Click on the diagram to learn about User defined graphs.

See also:

Predefined Graphs

Graph templates

Exporting data

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The XY program
The XYWin program

PEARL uses the graphical program XYWIN (Van Heerden and Tiktak, 1994). After you have pressed the 'Graph' or 'Graph using template' button in the Graphs forms, a graph window will appear. Press <Esc> on the keyboard to leave the graph.

Zooming

Printing graphs

Exporting graphs

Full version of XYWIN

Graph templates

Zooming

You can:

•	Zoom in with the left mouse button

•	Zoom out to the original size by using the Edit menu or press F8).

The zoom function is not available in predefined graphs.

Tip: If you want to have a rather accurate reading of a value in your graph, zoom in and read the value in the title bar (upper part of window).

Printing graphs

Graphs can be printed from the XYWIN menu (select Print from the File menu or press Cntrl+P). You will be asked to set-up the graph. Use:

•	Landscape orientation in the case of user-defined graphs

•	Portrait orientation in the case of predefined graphs.

Exporting graphs

XYWIN can create various types of graphical formats:

•	PostScript files. Select Create PostScript file from the file menu or press F5.

•	Windows Enhanced Metafiles. Select Create Output files and then file type emf. You can also press F6.

•	Various other file formats ('create output file'), such as jpg, png, tiff, bmp, etc.

You will be asked to set-up the graph. Use:

•	Landscape orientation in the case of user-defined graphs

•	Portrait orientation in the case of predefined graphs.

The created graphs can be imported into a report or into a publication. To import the picture into WORD97 select Picture from the Insert menu, then select From File. Both the print function and the Create output file function ask for the orientation of the graph. For best results, select the orientation according to the actual graph.

Full version of XYWIN

The version distributed with PEARL is a limited XYWIN version. You can order a complete XYWIN version from CaseWare (caseware@wxs.nl). The complete version is distributed with a comprehensive user manual.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Plotting monitoring data
Graph templates

Use Graph templates to control the settings of user-defined graphs. The graph templates form can be access from the main menu (shortcut key ALT-G-T).

One graph templates can be combined with different graphs - prepare a number of them in advance.

The axis settings can be set by the graphical user interface. For each axis, you can set the minimum and maximum. You can also the the number of major and minor divisions (tic marks).

Graphs can be further customized in the XyWin commands box. Commands entered in the XyWin commands box will override default graph settings! A full description of XY and its command can be found in Van Heerden and Tiktak, 1992.

The following commands can be handy:

•	TITLE_1 and TITLE_2 can be used to set graph titles.

•	X_TEXT, Y1_TEXT and Y2_TEXT can be used to set the axis text

•	LEGEND and NO_LEGEND can be used to format the legend

•	YAXIS_NUMBER can be used to assign different Y-axes to individual data series

•	Y1_RIGHT, Y1_BOTH and X_TOP can be used to position the axes

•	X_AXIS, Y1_AXIS and Y2_AXIS  can be used to format the axes

•	ZERO_LINE can be used to plot a zero line

•	DATA can be used to plot additional data in the same graph, for example observation data

•	DRAW_MARKERS can be used to plot markers

•	DRAW_LINES can be used to format the connecting lines

User defined graphs

Example template for plotting monitoring data

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Exporting data

To export data to an ASCII file, follow the same procedure as you would have followed when creating a User defined Graph.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Introduction
The command line version of PEARL

This section contains a description of the command-line version of PEARL. The command-line version is interesting for those who want to use pe arl in a batch environment. It also interesting for performing uncertainty- and sensitivity analyses or inverse modeling exercises. In all other cases we recommend the use of the User Interface. This interface has some distinct advantages, such as automatic generation of input files, data-storage in a relational data-base, easy access to scenarios, and an integrated viewer.

Please realise that the command-line version is only suitable for experienced users.

Running the model

File structure

Overview of the PEARL input file

Detailed description of the PEARL input file (prl file)

Listing of the PEARL input file

Description of the PEARL meteo file (met file)

Description of the PEARL output file (out file)

Description of the PEARL summary file (sum file)

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


File Structure

PEARL uses the Run ID to create the file names:

•	The PEARL input file has extension prl (e.g. 3.prl)

•	The detailed output file has extension out (e.g. 3.out)

•	The summary output file has extension sum (e.g. 3.sum)

•	The error file has extension err (e.g. 3.err).

•	The log file has extension log (e.g. 3.log)

All PEARL input files are ASCII files, which can be copied to another directory and edited.

Example files with a full description, including ranges, can be found in the defscen directory.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Weather and irrigation data file

PEARL uses daily weather data. THe weather data file has extension .met. The weather data file is an ASCII file existing of 11 space delimited columns. Depending on the evaporation option, some columns can be set to a no data value (e.g. -99.9).

Carefully check that the weather data file does not contain tabs.

Format of the weather data file

Example of a weather data file

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Introduction
Detailed description of the PEARL input file

The PEARL input file contains the following sections:

Nr	Section name	Kind of model parameters
1	Simulation control	Simulation options
2	Soil profile and soil properties	Soil profile, soil properties
3	Weather and irrigation data	File names for weather and irrigation data
4	Boundary conditions of hydrological model	Lower boundary flux and drainage/infiltration parameters
5	Compound properties	Compound properties
6	Management	Application and tillage
7	Initial and boundary conditions	Initial pesticide concentration and deposition
8	Crop section	Crop calendar and crop properties
9	Output control	Input/output options

Listing of the PEARL input file

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The detailed output file
Detailed output

The detailed output file has extension .out (see File locations) and contains output at regular intervals. The Detailed output file can be accessed through the View menu of the main form.

Detailed output is controlled from the Output Control tab of the main form. The output file is stored in the IODir.

The detailed output file contains records of the following format:

Time   Date   Identifier   Value(1)   …  Value(n)

where n is:

•	one in the case of variables that have no depth

•	the number of intended depths specified in the output control tab.

The detailed output file is suppressed if the 'detailed output' checkbox is not checked.

Fluxes will be printed cumulative if you have checked the Cumulative checkbox.

Example

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The summary output file
Summary output

The summary output file contains the annual balances and the report for the pesticide registration procedures. The Summary output file can be accessed through the View menu of the main form.

The following information is given:

•	Annual water balances of the FOCUS target layer.

•	Annual water balance of the entire soil profile.

•	Annual mass balance of substance in the FOCUS target layer.

•	Annual mass balance of substance in the entire soil profile.

•	Annual mass balance of substance at the crop canopy.

The rest of the summary file is used for creating reports.

The summary output file is an ASCII file, which can be copied.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Support and downloads
Support and downloading

Although we are not commercial suppliers, we do our best to help you. However, we hope that you will take some time to learn most of what you need to run the model. The following information is available for this purpose:

•	This Help file, which will guide you on-line. New users should start reading the Getting Started section. This help file contains descriptions of the structure of the PEARL user interface, model parameters and guidance on parameterisation.

 Using the help file

•	A comprehensive user-guide, including the theory, guidelines on model parameterisation and the old Dutch standard scenario (Tiktak et al., 2000). This guide contains most of what you need when using the model.

•	A background report, which contains a more fundamental description of the theory and considerations (Leistra et al, 2000).

•	A website will be opened, where you can download auxilliary programs, examples and the source code. Please notice that the JRC site is the only site where you can download the official FOCUS version of PEARL. If you cannot find the PEARL website, please contact us.

•	Registered users can join the PEARL mailing list. Here we will inform you about known bugs, new model versions and reports.

To get support from the PEARL team, you MUST register, even if you have downloaded from the JRC site. Without your registration, we cannot guarantee full support...

If, despite all our effort, you still encounter problems, contact us. Please do not use the address of one of the developers! Please remember: We need you to improve the model, so do not hesitate to mail comments and bugs. And don't forget: Positive comments are also welcome!

Read also the License agreement and disclaimer

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The project level

The highest level of the database (level 1) is the project level. Here, the user can group several model runs, based on a common criterion (e.g. all model runs for one single field-study or all model runs for one single pesticide).

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The model-run level

The second level is the model-run level. Parameters needed to perform a model-run are scenario data, pesticide data, the annual application schedule and the model-controls, such as the begin and end time of the simulation.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Main building-blocks level

The major building blocks of a model-run are stored at level 3. The main building blocks are scenario's, simulation control options, application schemes, deposition schemes and substances.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The scenario branch
Scenarios

The left hand side of the diagram shows the building blocks of the FOCUS scenario's. These are the parameters that one will usually find spatially distributed (see e.g. Vaughan and Corwin, 1994) and that will be used for building mega-plots or unique combinations in regional-scale assessments (Tiktak et al.,1996). Also parameter values referring to real locations (fields or lysimeters) can be entered through the scenario entry. Scenario's as defined by the FOCUS modelling working group are a combination of crop, location, the long-term application schedule (i.e. annual, biennial or triennial applications) and agronomic parameters (particularly irrigation data) to be used in the simulation. Parameters referring to a location can be further classified into soil parameters, weather data, parameters describing the regional groundwater system (i.e. the lower boundary of the hydrological model) and parameters describing the local groundwater system (i.e. water flow to ditches and field drains). Notice that in the pearl context, the crop calendar does not relate to a location. Instead, it is one of the building blocks of a scenario, which is at a higher hierarchical level. As shown in the figure, the crop calendar relates to individual crops. The crop calendar may refer to one single crop (monoculture) or several crops. At the lowest hierarchical level are the basic data, relating to a single crop stage, a single soil horizon, etc.

References

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Substance data

The right hand side of the diagram contains the substance data, not including application schemes. The pesticide entry is only used to refer to the name of the compound that has been applied (the parent compound), the actual data are entered in the compound tables, which are at level 5. The pesticide entry relates to a transformation schedule, which gives the relationships between the individual compounds to be simulated (the relevant reaction products, including the parent compound). The compound table relates to tables containing general compounds properties, sorption parameters, diffusion parameters and crop interaction parameters.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Application schemes

The annual application schemes and pesticide deposition data are both pesticide and location dependent. This table relates to the table describing the individual application events, which contains information about such parameters as dosage, application mode, application date, etc. As the annual application schedule cannot be directly linked with the pesticide or location tables, they are directly linked with a model run (level 2). Notice that, contrary to the annual application schedule, the long-term application schedule (i.e. whether a pesticide is applied annually, biennially or triennially) is part of a scenario. The reason is that we follow the choices made by the FOCUS modelling working group (FOCUS, 2000).

References

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Simulation control

All other parameters can accessed through the 'simulation control' entry. Here you will find parameters like start-time of the simulation, minimum time-step, output options, etc.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The agricultural year

In PEARL you can enter a crop calendar in one table. However, the SWAP model uses the concept of agricultural years. In the case of monocultures, you do not need to bother about this concept. If, however, your crops calendars contains more than one crop cycle, you have to specify the start month of the agricultural year. Specify the start month of the agricultural year in such a way that no single crop cycle contains this month. Consider the following example (The Repeat Crops check box is switched off to enable input of crop properties per year):

15-Apr-1980	08-Oct-1980	sugar beets

01-Nov-1980	10-Aug-1981	winter cereals

15-Apr-1982	08-Oct-1982	sugar beets

10-May-1983 	15-Sep-1983	potatoes

01-Nov-1983	10-Aug-1984	winter cereals

15-Apr-1985	08-Oct-1985	sugar beets

The only possible agricultural year runs from November until October, i.e. the start month of the agricultural year should be November. All other agricultural years would interfere with one of the crop cycles.

Another problem with the use of the agricultural year is encountered if you have checked the Repeat Crops checkbox in combination with multiple crops. In this case, the crops must be sorted so that the first crop is also the first crop in the actual agricultural year. The following crop calendar is illegal in combination with repeat crops (agricultural year starts in November):

15-Apr	08-Oct	sugar beets

01-Nov	10-Aug	winter cereals

The following one is valid:

01-Nov	10-Aug	winter cereals

15-Apr	08-Oct	sugar beets

Building a crop calendar

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Opening another database

PEARL offers the opportunity to open another database. This can be handy if you want to interchange data with other users.

Warning: Make sure that the database is not copied into the same directory as the original database. This can interfere with existing model runs!

The database must be compatible with the current PEARL version.

To open another database select File from the main menu and then Open another Database.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Maximum ponding depth

The maximum ponding layer thickness determines the maximum thickness of the water layer that can be present on the soil profile before surface runoff starts. Its value is usually below 0.05 m.

The Locations form

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Boundary air layer thickness

The calculation of  the volatilisation flux of pesticide requires the thickness of the laminar air boundary layer. There is considerable uncertainty about the thickness of the air boundary layer. Also it is not yet known whether this layer exists permanently in space and time (Freijer et al., 1996). Values that have been published for the thickness of the laminar layer range from a few mm to a few cm (e.g. Jury et al., 1983).

The Locations form

Theory

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Inital and boundary conditions
Initial and boundary conditions

The initial condition for the model is defined by profiles of the concentration of pesticide in the equilibrium domain of the soil system, c*eq (kg/m3), and in the non-equilibrium domain of the soil system, c*ne (kg/m3). It is further assumed that at the start of the simulation the areic mass of pesticide at  the plant surface, Ap, is zero.

The boundary condition at the soil surface is a flux boundary condition. The user can enter deposition fluxes of pesticide as a function of time. Pesticides entering the system by deposition are subject to canopy processes.

At the lower boundary of the soil system, dispersive and diffusive fluxes of pesticide are assumed to be zero. In the case of upward seepage of water from a deep aquifer, the pesticide concentration is set to zero.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Calculation of the pesticide volatilization flux
Calculation of pesticide volatilization flux

Diffusion of pesticide vapour in the gas phase of the soil is included in the model, which implies that a description of pesticide volatilisation at the soil surface is required. In the current model version, the diffusion of vapour through the soil and a laminar air-boundary layer are the limiting factors for volatilisation (cf. Jury et al., 1990):

where Jp,v (kg m-2 d-1) is the mass flux of pesticide volatilisation, cg (kg/m3)  is concentration of pesticide in the gas phase of the top layer, rs,v (d/m) is resistance of the soil boundary layer, and ra,v (d/m) is resistance of the air boundary layer. The resistance of the boundary layers are calculated by:

where ds (m) is thickness of soil boundary layer, Ddif,g (m2/d) is the coefficient for diffusion of pesticide in the gas phase of the soil system, da (m) is the thickness of the laminar air-boundary layer, and Da (m2/d) is coefficient for diffusion of pesticide in air. It should be noted that the current description of pesticide volatilisation is subject to considerable uncertainty, for surface-applied pesticides where initial volatilisation is hardly limited by the soil boundary layer. For this reason, at present research aimed at improving the submodel for pesticide volatilisation from a surface film is being carried out. See Leistra et al. (2000) for further considerations.

The locations form

Transport in the gas phase

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Non default factors for the effect of depth on transformation and sorption

Factors for the effect of depth on transformation and sorption are usually specified as a function of soil horizon. These factors are introduced into the "default factors for the effect of depth" box of the soil profiles form. Some substances show different depth dependency. These factors can be introduced here:

•	First select an existing substance form the Substance Code dialog;

•	Then introduce corresponding factors.

•	Repeat this step for all soil horizons:

-	First return to soil profiles form (Close);

-	Then select the next soil horizon;

-	Go back to this form again.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


To build a new soil profile do the following:
To build a new soil profile do the following

•	Split the soil profile into a number of soil horizons. These horizons must have distinctive soil chemical and soil physical properties.

•	Make a sketch of the soil profile, showing the lower boundary of the soil horizons. Calculate the thickness of the individual soil horizons. Carefully select the number of numerical compartments. See also vertical numerical discretization.

Now, make sure that all the information that is required for building a soil profile is already in the database. You can only select from existing building-blocks.

•	Decide whether you want to use one of the soil building blocks already available in the PEARL database. If not, then:

-	Enter the Soil Building Blocks form with browse button to the right of the Soil Building Block combo-box.

-	Add a new Building Block and enter the required soil properties.

-	Go back to the Soil profile form.

At this point, all basic information is available. You can now proceed with building the actual soil profile!!

•	Type + in the navigator of the browse box to add a new soil profile.

-	Fill in the upper part of the form.

•	Add soil horizons by pressing + in the lower part of the soil profiles form.

-	Fill in the form.

-	Select an existing soil building block in the building blocks combo box. One building block can be attached to different soil horizons!

•	Repeat the preceding step until all soil horizons have been defined.

•	Press Close when all done

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Relative diffusion coefficients

The relative diffusion coefficient can be calculated according to Millington and Quirk (1960), Currie (1960) and Troeh et al. (1982). Depending on the type of function chosen in the Soil profiles form, the user must specify parameter values for one of the three functions.

Different parameter values can be provided for diffusion in the liquid and gas phases. We will only describe the function for diffusion in the liquid phase - the other function is analogous.

•	The Millington and Quirk relationship requires two parameters, an exponent in the nominator and an exponent in the denominator:

−	Exponent Dif Liquid Mil Nom. Its value must be between 0.1 and 5.

−	Exponent Dif Liquid Mil Den. The range is 0.1 - 2.

The default values for the parameters in the Millington Quirk relationship are 2 and 2/3, respectively. These values are based on Jin and Jury (1996).

•	The Currie relationship requires:

−	A coefficient, which must be greater than 0.

−	An exponent, which must be greater than 1.

Parameter values for the Currie relationship have been reported for a wide range of Dutch soils in Bakker et al.(1987). The default values in PEARL are 2.5 and 3.0, respectively. These values are valid for weakly and moderately aggregated plough layers of loamy and humic sandy soils.

•	Also the Troeh relationship requires two parameters:

−	A coefficient, which must be in the range 0-1

−	An exponent, which must be in the range 1-2.

The default values are 0.05 m3/m3 and 1.4, respectively. More detailed information on these parameters is given in Jin and Jury (1996).

The Soil Profiles form

Theory

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Actual soil evaporation

PEARL calculates the actual soil evaporation rate using the equation proposed by Boesten and Stroosnijder (1986). Wesseling et al. (1990) gave values for â in the range of 0.54 to 0.96 cm(1/2). Boesten (1986) analysed literature data and concluded that there was no significant correlation between soil texture and â.

This implies, that the full range (0.54 to 0.96 cm(1/2)) applies to any soil type.

The Soil Profiles form

Theory

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Bulk density

If the bulk-density is not available, it can be estimated with a continuous pedotransfer function (Bollen et al., 1995):

where ñb (kg/m3) is the dry bulk density and mom (kg/kg) is mass content of organic matter.

The Soil Profiles form

Soil building blocks

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Soil horizons

In the soil horizons box, you have to enter parameter values for individual soil horizons. Also the vertical discretization of a soil profile must be described here. The Soil Horizons box is part of the Soil Profiles form. In the Browse Soil Horizons box, you can select, add, or delete soil horizons, using the navigator.

A soil horizon is a soil layer as found 'in reality'. It is assumed to have uniform chemical and physical properties. For numerical reasons, we assume that a soil horizon consists of a number of layers, called numerical compartments. See also the accompanying figure.

The following parameters, which apply to a soil horizon, must be provided in the Edit Soil Horizons box:

•	The horizon sequence number. Horizons must be given a number between 1 and 10; the topmost horizon has number 1.

•	The thickness of the horizon (m). The thickness must be greater than zero

•	The number of numerical compartments. The number of numerical compartments is a compromise between accuracy and computation time.

•	The dispersion length (m). The dispersion length must be greater than 0.5 X the distance between two nodal points. See guidance.

•	The soil physical and soil chemical characterisation of the soil horizon. PEARL uses the concept of generic building-blocks for these soil properties. Existing building blocks can be selected using the combo-box. New building blocks can be added using the browse button to the left of the combo-box.

Soil profiles

Soil building-blocks

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Vertical discretization of the model

In PEARL, soil properties are specified as a function of soil horizons. A soil horizon is assumed to have uniform chemical and physical properties. The current system allows for the definition of up to 10 soil horizons. Soil horizons are divided into numerical compartments. These compartments are represented by nodal points, which are situated in the centre of the layers which gives an example for 9 soil compartments and 3 soil horizons). The maximum number of nodal points is currently set at 500.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Number of numerical compartments

The number of soil layers is a compromise between accuracy and computation time. Computation time increases approximately with the square of the number of soil layers. On the other hand, predictions may become inaccurate if the layer thickness is taken too large. This is particularly true if the expected concentration in the groundwater is lower than 0.001ìg/L  (Leistra et al., 2000).

For most simulations a layer-thickness of 2.5 cm in the top 30 cm, 5 cm in the 0.3-1 m soil layer and 10 cm in the layer below 1 m is fair compromise.

The number of soil compartments must be chosen so that the distance between two nodal points is smaller than 2 times the dispersion length:

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The dispersion length

The coefficient of dispersion is used in the convection-dispersion equation for substance transport. The dispersion length of the soil generally varies between 0.03 and 0.10 m (Van Ommen et al. (1989). The default value in PEARL is set to 0.05 m, which is the average of values reported by Van Ommen et al. (1989).

Editing soil horizons

Theory

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The Richards equation

The SWAP model, which is the hydrological submodel of PEARL (Van Dam et al., 1997) uses a finite-difference method to solve the Richards equation:

where C(h) (1/m) is differential water capacity, t (d) is time, z (m) is vertical position, h (m) is soil water pressure head, K(h) (m/d) is unsaturated hydraulic conductivity, Ru,L (m3 m-3 d-1) is volumic volume rate of root water uptake, and Rd,L (m3 m-3 d-1) is volumic volume rate of lateral discharge by drainage.

PEARL uses analytical functions to describe the soil hydraulic properties.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The Mualem-Van Genuchten functions

The hydraulic properties are described with analytical functions. PEARL uses the equations proposed by Van Genuchten (1980):

and

where θs (m3/m3) is the saturated volume fraction of water, θr (m3/m3) is the residual volume fraction of water, α (1/m) reciprocal of the air entry value, Ks (m/d) saturated hydraulic conductivity, n (-) and λ (-)  are parameters, m = 1-1/n, and Se (-) is the relative saturation, which is given by:

If hysteresis is simulated, the user must specify two values for alpha, i.e. one for the main wetting curve and one for the main drying curve.

The Richards equation.

Parameter values for the Mualem-Van Genuchten functions

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Parameter values for the Mualem-Van Genuchten functions
Parameter values for the Mualem-Genuchten functions

Soil water flow is described with the Richards equation, which requires the Mualem-van Genuchten functions. Parameter values for the Mualem-Van Genuchten functions can be obtained by fitting experimentally derived retention data to the equations, using the RETC program (Van Genuchten et al., 1991). See Van Dam et al. (1997) for an overview of experimental procedures to obtain the soil hydraulic characteristics. Parameter values for the Van Genuchten (1980) analytical functions can be found in a number of international and national databases (e.g. Carsel and Parrish, 1988; Yates et al., 1992; Wösten et al, 1994; Leij et al., 1996). The accompanying table summarises parameter values derived from a database of over 600 soil samples in the Netherlands, known as the Staring Series (Wösten et al., 1994). The Staring Series correspond to the legend of the 1 : 50 000 soil map of the Netherlands. The definition of the classes is primarily based on soil texture and organic matter content (click here), with a distinction between topsoil- and subsoil layers.

The Staring Series can be used in first-tier assessments and regional-scale applications. In the case of more detailed studies (e.g. field-studies), on-site measured data should preferably be used (Tiktak et al., 1998).

The Staring Series

Dataset of soil hydraulic functions (Wösten et al., 1994), based on Dutch texture classes. The function are described with the analytical model of Mualem-Van Genuchten (1980).

TOP	èr	ès	Ks	á	ë	n

Soils	(m3 m-3)	(m3 m-3)	(cm d-1)	(cm1)	()	()

Sand

B1	0.01	0.43	17.46	0.0249	-0.140	1.507

B2	0.02	0.43	9.65	0.0227	-0.983	1.548

B3	0.01	0.45	17.81	0.0152	-0.213	1.412

B4	0.01	0.42	54.80	0.0163	0.177	1.559

Loam

B7	0.00	0.40	14.07	0.0194	-0.802	1.250

B8	0.00	0.43	2.25	0.0096	-2.733	1.284

B9	0.00	0.43	1.54	0.0065	-2.161	1.325

Clay

B10	0.01	0.42	1.17	0.0118	-4.795	1.224

B11	0.00	0.60	5.26	0.0243	-5.395	1.111

B12	0.00	0.55	15.46	0.0532	-8.823	1.081

Silt

B14	0.01	0.42	0.80	0.0051	0.000	1.305

Peat

B16	0.00	0.73	13.44	0.0134	0.534	1.320

B17	0.00	0.72	4.46	0.0180	-0.350	1.140

B18	0.00	0.77	6.67	0.0197	-1.845	1.154

SUB	èr	ès	Ks	á	ë	n

Soils	(m3 m-3)	(m3 m-3)	(cm d-1)	(cm1)	()	()

Sand

O1	0.01	0.36	13.21	0.0224	0.000	2.167

O2	0.02	0.38	15.56	0.0214	0.039	2.075

O3	0.01	0.34	18.30	0.0211	-0.522	1.564

O4	0.00	0.36	53.10	0.0216	-0.520	1.540

O5	0.01	0.32	43.55	0.0597	0.343	2.059

O6	0.00	0.41	5.48	0.0291	-6.864	1.152

Loam

O8	0.00	0.47	9.08	0.0136	-0.803	1.342

O9	0.00	0.46	2.23	0.0094	-1.382	1.400

O10	0.00	0.49	2.22	0.0107	-2.123	1.280

Clay

O11	0.00	0.42	13.79	0.0191	-1.384	1.152

O12	0.00	0.56	1.14	0.0095	-4.171	1.159

O13	0.00	0.57	3.32	0.0171	-4.645	1.110

Silt

O14	0.00	0.38	0.36	0.0025	0.057	1.686

O15	0.01	0.41	3.70	0.0071	0.912	1.298

Peat

O16	0.00	0.89	1.07	0.0103	-1.411	1.376

O17	0.00	0.86	2.75	0.0127	-1.832	1.274

Building-blocks of the Staring Series

Silt fraction, clay fraction, median particle size and organic matter content for the units of the Staring Series

TOP	Nomenclature	fsilt	fclay	mom	M50

Soils	(%)	(%)	(%)	(ìm)

Sand

B1	Loam-poor fine sand	0-10	0-15	105-210

B2	Slightly loamy fine sand	10-18	0-15	105-210

B3	Loamy fine sand	18-33	0-15	105-210

B4	Very loamy fine sand	35-50	0-15	105-210

Loam

B7	Light sandy clay	8-12	0-15

B8	Sandy clay	12-18	0-15

B9	Heavy sandy clay	18-25	0-15

Clay

B10	Light clay	25-35	0-15

B11	Clay	35-50	0-15

B12	Heavy clay	50-100	0-15

Silt

B14	Silty loam	85-100	0-15

Peat

B16	Sandy peat	0-8	23-100

B17	Peaty clay	8-100	16-45

B18	Clayey peat	8-100	25-70

SUB	Nomenclature	fsilt	fclay	mom	M50

Soils	(%)	(%)	(%)	(ìm)

Sand

O1	Loam-poor fine sand	0-10	0-3	105-210

O2	Slightly loamy fine sand	10-18	0-3	105-210

O3	Loamy fine sand	18-33	0-3	105-210

O4	Very loamy fine sand	35-50	0-3	105-210

O5	Coarse sand	0-3	210-2000

O6	Glacial till	0-50	0-3	50-2000

Loam

O8	Light sandy clay	8-12	0-3

O9	Sandy clay	12-18	0-3

O10	Heavy sandy clay	18-25	0-3

Clay

O11	Light clay	25-35	0-3

O12	Clay	35-50	0-3

O13	Heavy clay	50-100	0-3

Silt

O14	Sandy loam	50-85	0-3

O15	Silty loam	85-100	0-3

Peat

O16	Sandy peat	0-8	35-100

O17	Clayey peat	8-100	35-100

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Viewing the weather data

In this form, the weather data can be viewed and graphed. The columns have the following meaning:

Date:	Between 1900 and 3000

RDD:	Daily global radiation (kJ m-2 d-1), between 0 and 5 E6

TMMN:	Minimum daily temperature (deg C), between -50 and 35

MMMX:	Maximum daily temperature (deg C), between -30 and 60

VP:	Average vapor pressure (kPa), between 0 and 10

WN:	Average windspeed (m/s), between 0 and 50

RAIN:	Daily precipitation (mm/d), between 0 and 1000

ETREF:	 Reference evapotranspiration (mm/d), between 0 and 100

Some of the columns are not required if. Click here for more information.

See also the Meteo stations form.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The lower boundary condition of the hydrological model

PEARL makes a distinction between the local drainage flux to ditches and drains and the seepage flux due to regional groundwater flow. The seepage flux due to regional groundwater flow is the lower boundary flux (qb), the local drainage flux is treated as a sink term (Rd,L).

The following lower boundary conditions can be used in PEARL:

•	Regional bottom flux qb (m3 m-2 d-1) specified as a function of time (Neumann condition).

•	Regional bottom flux is calculated using the hydraulic head difference between the phreatic groundwater and the groundwater in the semi-confined aquifer (pseudo two-dimensional Cauchy condition (see also figure);

where Φaqf (m) is hydraulic head of the semi-confined aquifer, Φavg (m) is average phreatic head, and γaqt (d) is vertical resistance of the aquitard. The average phreatic head is determined by the shape of the groundwater level in a field. The average phreatic head is calculated using the drainage base, Φd (m) and a shape-factor, βgwl:

Possible values for the shape factor are 0.64 (sinusoidal), 066 (parabolic), 0.79 (elliptic) and 1.00 (no drains present). Seasonal variation of the bottom flux can be induced through a sine-wave of the hydraulic head in the semi-confined aquifer.

•	qb is calculated from an exponential flux-groundwater level relationship (Cauchy condition):

with ag (m d-1) and bg (m-1) as empirical coefficients.

•	Pressure head of the bottom soil layer specified as a function of time (Dirichlet condition).

•	Zero flux at bottom of soil profile: qb = 0 (special case of Neumann condition).

•	Free drainage of soil profile, in which case unit gradient is assumed at the lower boundary: qb = -KNumLay (special case of Neumann condition).

•	Lysimeter boundary condition: Outflow only occurs if the pressure head of the bottom soil layer is above zero (special case of Neumann condition).

The Lower Boundary conditions form.

The drainage levels form

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Local drainage to ditches and field-drains.

PEARL makes a distinction between the local drainage flux to ditches and field-drains and the seepage flux due to regional groundwater flow. The seepage flux due to regional groundwater flow is the lower boundary flux (qb), the local drainage flux is treated as a sink term (Rd,L).

Lateral discharge rates can be calculated for a maximum number of five local drainage systems (e.g. drainage tiles and field-ditches). PEARL uses the following equation to calculate the flux to drainage system k:

where qd,k (m3 m2 d1) is the flux of water to local drainage system k, Öd,k (m) is hydraulic head of drainage system k, and ãd,k (d) is drainage resistance. In order to distribute the discharge rates over the soil layers, first a discharge layer is determined by considering a travel-time distribution. The most important assumption in this computational procedure is that lateral discharge occurs to parallel, equidistant water courses (distance Lk (m)). See chapter 10.1 in Van Dam et al. (1997) for details. Within this discharge layer, the lateral drainage from soil layer i to local drainage system k, Rd,L,k,i, (m3.m3.d1) is calculated with the equation:

The total lateral drainage is calculated by summing the lateral drainage for all local drainage systems.

The drainage levels form

Lower boundary condition of the hydrological model

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


To build a new crop calendar do the following

First go to the Crop Calendars form. If you want to add a new crop, don't do anything there now - first create the Building Blocks of your crop.

•	Enter the Crops Form with the browse button to the right of the Crops combo-box.

-	Add a new Crop, enter the crop properties in the Edit Crops box and Save.

-	Enter the Root Density form by pressing the Root Density button. Edit the relative root density distribution. Save and Go Back.

-	Go back to the Crop Stages form.

•	Go back to the Crop Calendars form.

•	Add a new Crop Calendar with the browse button in the upper part of the Crop Calendars form.

-	Fill in the upper part of the form

-	Carefully select the appropriate 'Repeat Crop Calendars' option. - Switching it on repeats the Crop calendar in each year.

-	Save your changes with the Confirm button

•	Add a Crop to the Crop Calendar.

-	Fill in the Emergence and Harvest dates. Also fill in the number of years of emergence and harvest, relative to the start year (0 indicates the start year, 1 is the 1st year after the start of the simulation, etc). In the case of repeated crops, only 0 and 1 are relevant.

-	If the 'repeat crops' checkbox in the upper part of the form is marked, the crop calendar for a single year is required only.

-	Save your changes with the Confirm button

-	Enter the Crop Stages form with the browse button.

•	Add one or more crop Stages.

•	Edit the Crop Stages.

•	Save and Go Back to the Crop Calendar form.

•	If wanted, add another crop.

-	PEARL will simulate bare soil at times that no crop is present.

•	Go back to the main form.

Crop calendars

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Crop Calendars

The Crop Calendars box is part of the Crop Calendars form. In the Browse Crop Calendars box, you can select, add, or delete crop calendars, using the navigator. The following parameters, which apply to the crop calendar as a whole, must be provided in the Edit Crop Calendars box:

•	A unique code

•	The name of the crop calendar

•	The Crop Cycle option. The course of development stage with time can be:

-	Variable over the years. In this case, the course of development stages with time is controlled by the temperature sum. Threshold temperature sums must be given in the Crops Stages form.

-	Fixed over the years. In this case, the development stage is linear in time. No additional parameters are required.

•	The Repeat Crops switch. If checked, one crop calendar is repeated every year. If the crop calendar contains one crop only, a monoculture is simulated.

Carefully select the appropriate 'Repeat Crop Calendars' option. Switching it on or off has big consequences for the final results!

Crop calendar form

Crops

Crop stages

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Crops

The Crops box is part of the Crop Calendars form. In the Browse Crops box, you can select, add, or delete crops, using the navigator.

Most crop properties must be entered in the Crops form, which can be accessed with the browse button to the right of the Crops combo-box. The only parameters that must be specified here are:

•	An existing crop must be selected in the Crops combo-box. Make sure that all crops that you want to use are already in the database.

•	The sequence number. The first crop in the crop calendar has sequence number 1.

•	The emergence (not seeding) date of the crop.

•	The harvest date of the crop.

•	The year of crop emergence and harvest, relative to the start year. The years are offsets, so specify 0 for a crop that grows in the start year.

One crop can be used with different emergence and harvest dates.

Crop calendar form

Crop stages

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Root density table

The root density table is accessible from the Crops form. The user may define up to 11 data pairs to define the relative root density distribution as a function of the relative rooting depth.

Any unit can be used, the model will normalise the root density distribution in such a way that the integral of root density over the root zone equals one.

The depth distribution of water uptake is based on the root length distribution. The FOCUS modelling Working Group (FOCUS, 2000) compiled an overview of the maximum rooting depth as a function of development stage for some European crops. See also Van den Berg et al. (2000).

Root water extraction

Potential transpiration

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Root water extraction function

The maximum possible root water extraction rate, integrated over the rooting depth, is equal to the potential transpiration rate, Tp (m/d). The potential root water extraction rate at a given depth, Ru,L,p (z) (m3 m-3 d-1), is calculated from the volumic root length, Lroot (z) (m/m3) at that depth as a fraction of the integrated volumic root length (Tiktak and Bouten, 1992):

Notice that SWAP does not account for preferential uptake from layers with high relative water saturation (Herkelrath et al., 1977; Tiktak and Bouten, 1992). The actual root water extraction rate, Ru,L, is calculated using a reduction function (Feddes et al., 1978):

PEARL uses a trapezoidal function to describe the ratio between actual and potential transpiration rate.

Legend: h1 = The anaerobiosis point; h2 = The reduction point at near-saturation; h3l and h3h are the two reduction points in the dry range; and h4 is the wilting point.

The Crops form

Potential transpiration

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Guidance on critical pressure heads

The table gives a summary of critical pressure heads in the trapezoidal root water extraction function for some common arable crops.

Critical pressure heads (cm) of the sink term reduction function for some main arable crops (Wesseling, 1991).

Crop	h1	h2	h3h	h3l	h4

Potato	-10	-25	-320	-600	-16000

Sugar beet	-10	-25	-320	-600	-16000

Wheat	0	-1	-500	-900	-16000

Pasture	-10	-25	-200	-800	-8000

Corn	-15	-30	-325	-600	-8000

Theory

The Crops form

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Extinction coefficient

The extinction coefficient (ê) is required in the equation, which partitions the potential evapotranspiration into the potential transpiration and the potential soil evaporation. Feddes et al. (1978) used ê = 0.39 for common arable crops. More recent studies showed that ê is crop dependent, and often higher. In PEARL, a default value of 0.5325 is used.

The Crops form

Theory

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Interception of water

Interception of rainfall by the crop canopy is calculated from the empirical equation (Braden, 1985):

where Pi (m3 m-2 d1) is intercepted precipitation, P (m3 m-2 d1) is precipitation, SC (-) is the fraction of the soil covered by the crop, and a is an empirical parameter. In SWAP, the fraction of the soil covered by the crop is approximated by LAI/3 (Van Dam et al., 1997).

This equation shows that at increasing rainfall amounts, the amount of intercepted water asymptotically reaches aLAI. Braden (1985) analysed interception data for a number of agricultural crops and found that parameter a is approximately 0.25 for common agricultural crops. This value is the default value in PEARL.

The Crops form

Potential evapotranspiration

Potential transpiration and potential soil evaporation

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Minimum canopy resistance

The minimum canopy resistance is used in the Penman-Monteith equation and ranges from 30 s/m for arable crops to 150 s/m for trees in forests; its default value is 70 s/m. See Allen et al. (1989) for parameter values.

The Crops form

The Penman-Monteith equation

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Potential evapotranspiration

The potential evapotranspiration is the key factor affecting the uptake of water by plant roots and soil evaporation. The potential evapotranspiration can be calculated with the Penman-Monteith approach or with the (simpler) Makkink approach. Recent comparative studies have shown a good performance of the Penman-Monteith approach under varying climatic conditions (Jensen et al.,1990). We recommend the use of the Penman-Monteith approach if sufficient data is available.

The Penman-Monteith approach

The Makkink approach

The Meteo Stations form

The Penman-Monteith approach

Potential and even actual evapotranspiration calculations are possible with the Penman-Monteith equation, through the introduction of canopy and air resistance to water vapour diffusion. However, canopy and air resistance may not be available. PEARL uses a slightly modified version of the Penman-Monteith equation (Monteith, 1965; Van Dam et al., 1997) to calculate the potential evapotranspiration. This comes down to a two-step approach:

•	The calculation of the potential evapotranspiration, using the minimum value of the canopy resistance and the actual air resistance, and

•	The calculation of the actual evapotranspiration using a reduction function.

Application of  the Penman-Monteith equation requires values of the air temperature, solar radiation, wind speed and air humidity (see meteo stations). PEARL calculates three quantities with the Penman-Monteith equation (see also the theory on potential transpiration and potential soil evaporation):

•	ETw0 (m/d)	The potential evapotranspiration of a wet canopy, completely covering the soil

•	ETp0 (m/d)	The potential evapotranspiration of a dry canopy, completely covering the soil

•	Ep0 (m/d)	The potential evaporation of a wet, bare soil.

Crop stages

The (simpler) Makkink approach

Potential transpiration and potential soil evaporation

The Makkink approach

As wind speed and air humidity are not always available, PEARL can alternatively calculate the reference evapotranspiration according to Makkink (1957), which requires daily values of temperature and solar radiation only. This equation, however, has some limitations: (i) it is developed for Dutch climatological conditions, and (ii) due to the lack of a ventilation term its performance in winter conditions is relatively poor.

The potential evapotranspiration rate of a dry canopy, ETp0 (m d1) is calculated by:

where fc (-) is an empirical crop factor, which depends on the crop type, and ETr (m/d) is the reference evapotranspiration.

Notice that this approach does not allow differentiation between a dry crop, a wet crop and wet soil. PEARL therefore assumes that these quantities are equal (see also Penman-Monteith).

Crop stages

Potential transpiration and potential soil evaporation

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Potential transpiration and evaporation
Potential transpiration and potential evaporation

The potential evapotranspiration is partitioned into the potential transpiration and the potential soil evaporation (Belmans, 1983).

The potential soil evaporation rate from a partly covered soil, Ep (m d1) is given by

where LAI (m2 m-2) is the Leaf Area Index, ê (-) is the extinction coefficient for global solar radiation, and Ep0 (m d-1) is the potential evaporation rate of a wet bare soil (see chapter on potential evapotranspiration). As mentioned there the potential evaporation rate of a wet bare soil is equal to the potential evapotranspiration rate if the Makkink equation is used. The actual soil evaporation rate is calculated with a reduction function, which is based on the stage in the drying cycle.

PEARL calculates a daily average of the potential transpiration rate, taking into account the fraction of the day that the canopy is wet, fw (cf. Bouten, 1992):

where Tp (m d1) is the potential transpiration rate in the case of a partial soil cover. PEARL assumes that the evaporation rate of the water intercepted by the canopy is equal to the potential evapotranspiration rate of a wet canopy, independent of the soil cover fraction. The ratio of the daily amount of intercepted precipitation, Pi and ETw0 indicates the fraction of the day that the canopy is wet, fw ():

The actual transpiration rate is calculated using a reduction function.

The crops form

Potential evapotranspiration

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Actual soil evaporation rate

To calculate the actual soil evaporation rate, the potential soil evaporation rate is first limited to the maximum flux calculated from the Darcy equation for the top nodal point, Emax. The soil evaporation flux is additionally reduced according to the method proposed by Boesten and Stroosnijder (1986), who calculated the maximum actual soil evaporation, Ea (m) during a drying cycle:

where where â (m1/2) is an empirical parameter.

The crops form

Potential soil evaporation

Guidance on model parameters

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Guidance on parameters affecting the potential evapotranspiration

Depending on the data availability, the potential evapotranspiration can be calculated on the basis of the Penman-Monteith approach or on the basis of the Makkink approach. Because of good performance of the Penman-Monteith equation, we recommend the use of this equation if daily value of air-temperature, solar radiation, wind-speed and air-humidity are available. In other cases the simpler (and empirical) Makkink equation can be used.

Penman-Monteith approach

Makkink approach

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Guidance on crop factors

If the Makkink equation is used, crop-factors should be entered as a function of crop development stage. Crop factors in relation to the Makkink approach were presented by Feddes (1987) for some common Dutch arable crops. The FOCUS modelling Working group (FOCUS, 2000) compiled crop factors for common European crops. For the partitioning of the potential evapotranspiration, swap requires the Leaf Area Index as a function of development stage (see FOCUS (2000) for examples).

Crop stages

Makkink equation

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Left-hand side of application form
Application schemes

The application schemes box is part of the Application Schemes form. In the browse box, you can select, add, or delete application schemes.

To add a new application scheme, act as follows:

•	Press + at the navigator

•	Enter a unique code in the code field

•	Enter a short description of the application scheme in the description field

•	Add applications in the applications box (the right hand side of the form)

•	Press Close when done.

Tip: If you want to make a clone of an existing scheme, use the Copy button to make a copy of an existing scheme and edit this copy.

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Background
Background on application schemes

Processes that affect the fraction of the dosage that is introduced into the soil system are:

•	Interception by the crop canopy during spraying

•	Drift from the field to adjacent ditches and fields.

•	Dissipation at the soil surface by processes like film volatilisation and photochemical transformation.

In PEARL, the user can choose from two general methods to describe the dosage introduced into the system:

•	The processes at the soil surface and plant surface are simulated in a simplified way (application to the crop canopy).

•	Pesticide losses above the soil system are estimated beforehand, and the net load is introduced directly into the soil system (application to the soil surface).

Canopy processes

If the pesticide is applied to the canopy, canopy processes have to be simulated. The most important processes are:

•	Initial distribution over the plant canopy and the soil surface

•	Dissipation at the crop canopy

•	Wash-off from the crop canopy

All areic masses are expressed per m2 field surface.

Canopy processes

Editing application schemes

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Saturated vapor pressure

The saturated vapour pressure is temperature dependent. For this reason, both the temperature reflecting the experimental conditions and the saturated vapour pressure at that temperature must be provided. The saturated vapour pressure shows a wide range of values. Smit et al. (1997) have compiled data on the saturated vapour pressure. The default value of the saturated vapour pressure in PEARL is set to zero, which means that there will be no compound in the gas phase. The default value of the enthalpy of vaporisation is 95 kJ/mol, which is the average of available measurements as collected by Smit et al. (1997). Their data show a range from 58 to 146 kJ/mol.

Editing general substance properties

Gas transport

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Solubility in water

The solubility of a compound in water should be provided together with the temperature reflecting the experimental conditions. The default value for the molar enthalpy of dissolution is 27 kJ/mol, which is the average of measurements by Smit et al. (1997). Their data, which are all based on Bowmans and Sans (1985), show a range from -17 to +156 kJ/mol.

Editing general substance properties

Gas transport

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The Freundlich coefficient

PEARL has three options available to calculate the Freundlich sorption coefficient:

•	Kom, pH-independent: The Freundlich coefficient is calculated from the soil organic matter content and the coefficient for sorption on organic matter. This is the most common approach. This option requires one parameter, i.e.:

-	The coefficient for sorption on organic matter (L/kg), which must be greater than zero.

-	The temperature reflecting the experimental conditions during the sorption experiment (deg C). The temperature must be between 5 and 30 deg C.

-	The molar enthalphy of sorption (kJ/mol). Its value must be between -100 and 100 kJ/mol.

Guidance.

Temperature dependence of sorption

•	Kom, pH-dependent: The Freundlich coefficient is calculated with an equation that applies to the sorption of weak acids. This option requires four parameters:

-	The coefficient for sorption on organic matter (L/kg) under acidic conditions. Its value must be greater than zero.

-	The coefficient for sorption on organic matter (L/kg) under basic conditions. Its value must be greater than zero.

-	The negative decimal logarithm of the dissociation constant (pKa), which must be between 0 and 14.

-	A pH correction value, which must be between -2 and 0.

-	The temperature reflecting the experimental conditions during the sorption experiment (deg C). The temperature must be between 5 and 30 deg C.

-	The molar enthalphy of sorption (kJ/mol). Its value must be between -100 and 100 kJ/mol.

Guidance

Temperature dependence of sorption

•	Kf, user defined: In cases where the sorption of pesticides is dependent on other soil constituents than the organic matter content (e.g. oxide content or clay content), the Freundlich coefficient can be introduced directly. The following parameterKom, pH-independents must be provided:

-	The Freundlich coefficient (NOT the coefficient for sorption on organic matter!!) measured in topsoil. Its value must be greater than zero.

-	The temperature reflecting the experimental conditions during the sorption experiment (deg C). The temperature must be between 5 and 30 deg C.

-	The molar enthalphy of sorption (kJ/mol). Its value must be between -100 and 100 kJ/mol.

If this option is used, the user must also specify depth dependence factors of sorption (0-1). The form to introduce these factors can be reached through the soil profiles form.

The coefficient for sorption on organic matter

Temperature dependance of sorption

Theory on pH dependent sorption

Equilibrium and non-equilibrium domains

The sorption coefficient on oxides or clay

Back to the Freundlich sorption tab

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Freundlich exponent and reference concentration

The second part of the Freundlich tab contains two parameters:

•	The reference concentration in the liquid phase (mg/L), which must be within the concentration range of the simulation study. Its default value is 1 mg/L, its minimum value is 0.01 mg/L.

•	The Freundlich sorption coefficient (-), which must be between 0.1 and 1.3.

The Freundlich equation

Back to the Freundlich sorption tab

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Non equilibrium sorption

Non-equilibrium sorption is described with an equation that requires two additional parameters:

•	The desorption rate coefficient (1/d). Its value must be between zero and 0.5. You can switch off non-equilibrium sorption by setting the desorption rate coefficient to zero.

•	The factor describing the ratio between the Freundlich coefficient at the non-equilibrium sites and the Freundlich coefficient at the equilibrium sites (KF,Ne/KF,Eq). This ratio must be greater than zero.

Guidance

Theory on non-equilibrium sorption

Editing substance properties

The Freundlich equation

Back to the Freundlich sorption tab

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The Freundlich equation

The sorption of pesticide on the solid phase in soil is described with a Freundlich-type equation. Equilibrium sorption is described by the equation:

in which Xeq (kg/kg) is pesticide content in the equilibrium sorption phase, KF,eq (m3 kg1) is Freundlich coefficient for the equilibrium-sorption phase, cL (kg/m3) is concentration in the liquid phase, cL,r (kg/m3) is reference concentration in the liquid phase and N is the Freundlich exponent.

Notice that a particular type of Freundlich equation is used in the model, by introducing the reference concentration. The advantage of this type of equation is that the unit of the Freundlich coefficient becomes independent of the exponent.

Editing sorption parameters

The sorption coefficient on organic matter

The sorption coefficient on clay or (pedogenic) oxides

pH dependent sorption

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pH independent sorption

In the most common approach for pesticides, the Freundlich coefficient is calculated on the basis of the coefficient of equilibrium sorption on organic matter, Kom. This equation requires two parameters, i.e. Kom and the exponent, N. Average values of Kom have been compiled by Linders et al. (1994). The exponent, N, is usually in the range between 0.7 and 1.1 (Calvet, 1980). The average value of N is 0.9, which is also the default value in PEARL (Boesten and Van der Linden, 1991). These average values can be used for first-tier assessments. However, in more detailed field studies, the sorption coefficient and exponent should be obtained from soil material collected on-site (Boesten, 1991; Tiktak, 2000). The sorption points should be fitted to the Freundlich model. Tiktak et al. (1998) give an example for bentazone and ethoprophos.

Editing sorption parameters

The Freundlich equation

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Temperature dependance of sorption
Temperature dependence of sorption

The effect of temperature on both the equilibrium and the non-equilibrium Freundlich coefficient is described with:

in which the subscript ref indicates a reference temperature and in which ΔHs is the molar enthalpy of sorption (J/mol). The default value of ΔHs is 0 (no effect of temperature on sorption). Usually the Freundlich coefficients decrease with increasing temperature (Calvet et al., 1980), which implies that Hs is negative. However, sometimes positive values of ΔHs have been found (Dao and Lavy, 1978; Boesten and Van der Pas, 2000).

Back to the Freundlich sorption tab

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pH dependent sorption

If the Freundlich coefficient is dependent on the pH, the dissociation constant,  pKa, must be specified. The pKa can be taken from a handbook on chemical properties of pesticides (e.g. Tomlin, 1997). This equation requires two coefficients for sorption on organic matter, i.e. KomEqAc and KomEqBa. These two parameters can be obtained by fitting the equation describing the pH dependence to experimental sorption data. The accompanying figure gives the results of a sorption experiment with flumetsulam (Fontaine et al., 1991). In this experiment, the pH was varied from well below to well above the pKa of flumetsulam. The lines show the results of two fits: (i) with the pH correction set to zero, and (ii) with the pH correction fitted. In this particular case, both equation fitted the data well. In such a case, the equation without pH correction is preferred.

If no fitting program is available, the user can take the apparent Kom at pH values well below (more than 2 pH units), respectively well above the pKa value of the compound. Another use of the pH correction is to account for differences in experimental methods to measure the soil pH. The sorption of pesticides is often measured in a 0.01 M CaCl2 solution. If the soil pH has been measured in a different way (e.g. pH-KCl or pH-H2O), a correction may be required. The pH correction, ÄpH, may vary between –1 and 2. See  Leistra et al. (2000) for further considerations.

Editing sorption parameters

The Freundlich equation

Theory on pH dependent sorption

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Non-equilibrium sorption

The equation for non-equilibrium sorption requires two additional parameters, i.e. the desorption rate coefficient and the factor describing the ratio KFNe/KFEq, where KFNe is the Freundlich coefficient for the non-equilibrium sites and KFEq is the Freundlich coefficient for the equilibrium sites. Non-equilibrium sorption will not be simulated if the desorption rate coefficient is set to zero.

Boesten et al. (1987) found values of KFNe/KFeq ranging from 0.3 to 0.4 and desorption rate coefficients values ranging from  0.01-0.02 (1/d) for cyanazine and metribuzin in a sandy soil. Boesten and Gottesbüren (2000) found a value of KFNe/KFEq of 0.55 and a desorption rate coefficient of 0.015 (1/d) for bentazone in a sandy soil. If no further information is available, we recommend to use 0.5 for KFNe/KFEq and 0.01 (1/d) for the desorption rate coefficient as default values.

A compound residing in the non-equilibrium domain is not subject to transformation, which implies that the half-life of transformation refers to the equilibrium domain only. An important consequence is that the transformation half-life, which usually refers to the total mass content, should be obtained in a special procedure.

This new experimental and computation procedure also returns the desorption rate coefficient and the ratio KF,Ne/KF,Eq

Theory

Experimental and computation procedure for obtaining non-equilibrium sorption parameters

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Equilibrium and non-equilibrium domain of the soil system

Editing sorption parameters

The Freundlich equation

Theory on non-equilibrium sorption

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The coefficient for equilibrium sorption on organic matter

The Freundlich coefficient may depend on various soil properties, such as organic matter content, oxide content and pH. For most pesticides, the following equation is appropriate:

where mom (kg/kg) is mass content of organic matter in soil and Kom,eq (m3/kg) is the coefficient of equilibrium sorption on organic matter.

Editing sorption parameters

The Freundlich equation

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pH dependence of the coefficient for equilibrium sorption

PEARL contains a description of the sorption of weak acids, which is pH dependent:

where Kom,eq,ac (m3/kg) is the coefficient for sorption on organic matter under acidic conditions, Kom,eq,ba (m3/kg) is the coefficient for sorption on organic matter under basic conditions, M (kg/mol) is molar mass, pKa is the negative logarithm of the dissociation constant, and ΔpH is a pH correction factor. See Leistra et al. (2000) for the derivation of this equation. Under some conditions, the same type of equation can be used for weak-base pesticides (Leistra et al., 2000).

Editing sorption parameters

The Freundlich equation

The sorption coefficient on organic matter

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The Freundlich coefficient as a function of clay content or oxides

The sorption of some pesticides cannot be described with the organic matter equilibrium constant. This is particularly true for those pesticides that sorb preferentially on clay or oxides. In these cases, the user should specify the Freundlich coefficient of the topsoil and a depth-effect factor:

where KF,eq,r  (m3/kg) is the reference Freundlich coefficient in the topsoil, and  fd,s () is an empirical deptheffect factor.

Editing sorption parameters

The Freundlich equation

The sorption coefficient on organic matter

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Non-equilibrium sorption

Pesticide sorption to the non-equilibrium phase is described by a first-order rate equation:

where Rs (kg m3 d1) is rate of sorption in the non-equilibrium domain of the soil system, ñb (kg/m3) is the dry bulk density of the soil, Xne (kg/kg) is pesticide content at non-equilibrium sorption sites, kd (1/d) is desorption rate coefficient, and fK,ne () is factor describing the ratio KF,ne/KF,eq, with KF,ne (m3/kg) as the Freundlich coefficient for the non-equilibrium sorption phase. See Leistra et al. (2000) for a discussion of the theoretical background of this equation.

Editing sorption parameters

The Freundlich equation

The sorption coefficient on organic matter

The sorption coefficient on clay or (pedogenic) oxides

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Gas-liquid partitioning

The partitioning of the pesticide between the gas phase and the liquid phase is described by Henry's law:

in which cg (kg/m3) is the concentration of pesticide in the gas phase and KH (-) is the dimensionless Henry coefficient, which is calculated by:

where pv,s (Pa) is the saturated vapour pressure, M (kg/mol) is molar mass, Sw (kg/m3) is solubility in water, R (J mol-1 K-1) is the molar gas constant, and T (K) is the temperature. PEARL describes the temperature dependence of both pv,s, which requires the molar enthalpy of vaporisation, ÄHv (J/mol), and Sw, which requires the molar enthalpy of dissolution, ÄHd (J/mol):

and

Here, pv,s,r (Pa) is the saturated vapour pressure at reference temperature Tr (K) and Sw,r (kg m3) is the pesticide solubility in water at reference temperature.

The three-phase system

Gas transport

Editing general substance properties

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The total concentration of pesticide

The total concentration of pesticide in the equilibrium domain of the soil system (kg/m3) is given by:

where å (m3/m3) is volume fraction of the gas phase, cg (kg/m3) is concentration of pesticide in the gas phase, è (m3/m3) is volume fraction of the liquid phase, cL (kg/m3) is concentration of pesticide in the liquid phase, ñb (kg/m3) dry bulk density of the soil, and Xeq (kg/kg) is pesticide content in the equilibrium phase. The total concentration of pesticide in the non-equilibrium phase (kg/m3) is given by:

with Xne (kg/kg) as the pesticide content in the non-equilibrium phase.

The three phase system

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Mass balance equation
Mass balance equations

The mass balance equation is the most important equation solved by PEARL. Pesticide can be found in the equilibrium domain and in the non-equilibrium domain of the soil system, so two mass balances apply:

and

Here, c*eq (kg/m3) is the pesticide concentration in the equilibrium domain of the soil system, c*ne (kg/m3) is the pesticide concentration in the non-equilibrium domain of the soil system, Rs (kg m-3 d-1) is the volumic mass rate of pesticide sorption, Jp,L (kg m2 d1) is the mass flux of pesticide in the liquid phase, Jp,g (kg m2 d1) is the mass flux of pesticide in the gas phase, Rt (kg m3 d1) is the transformation rate, Rf (kg m3 d1) is the formation rate, Ru (kg m3 d1) is the rate of pesticide uptake by plant roots, and Rd (kg m3 d1) is the lateral discharge rate of pesticides.

Graphical representation of the soil phases

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Half-life

In PEARL, transformation is described by first-order kinetics. Average values for the half-life of 243 pesticides have been reported by Linders et al. (1994). These average values can be used for first-tier assessments. However, in more detailed field studies, the half-life time should be obtained by incubating the pesticide in soil material collected on-site (Boesten, 1991; Tiktak, 2000). The normal procedure is that the amount of pesticide ramaining in the top-soil material is measured at different times. Then, a first-order rate constant, kt (1/d), is calculated using linear regression of ln-transformed data or non-linear curve fitting. The experiment can be extended to obtain the half-life in subsoil material and the temperature dependence of transformation. See Tiktak et al. (1998) for an example.

In the case of pesticides that show sorption/desorption kinetics, a different procedure should be used to obtain the transformation half-life.

Editing transformation parameters

Theory

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Experimental conditions

The transformation half-life time is dependent on temperature, soil-moisture and depth in soil. The half-life time that is input in PEARL should be representative for transformation in the topsoil. This half-life time must be accompanied with the experimental conditions, i.e. the temperature (deg C) and the soil water content (kg/kg). The half-life time is often measured at 20 deg C and at a moisture content reflecting field-capacity (pF 2).

Editing transformation parameters

Temperature dependence of the half-life time

Moisture dependence of the half-life time

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The molar enthalpy of transformation

The dependency of the transformation rate coefficient on the temperature is described with an Arrhenius equation. Using the results of some 50 experiments, Boesten (1991) found an average value of the molar Activation energy in this equation of 55 kJ/mol, which was the value in the old Dutch standard scenario (Van der Linden and Boesten, 1989). The standard deviation for the activation energy was calculated to be 15 kJ/mol, with values ranging between 20 and 100 kJ/mol. In a more recent review, the FOCUS Soil Modelling Working Group (1997), found an average activation energy of 54 kJ/mol. This value is the default value in PEARL.

Editing transformation parameters

Temperature dependence of the half-life time

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The exponent of the Walker equation

The effect of soil moisture on the rate coefficient for transformation is described with an equation based on Walker (1974). Boesten (1986) reviewed the results of some  40 experiments with a range of compounds and soils, and found an average value of the exponent of 0.7. Its range was between zero and 2.8. The average value is taken to be the default value in PEARL. In a more recent review (based on more data) the FOCUS Soil Modelling Working Group (1997) found the same average value of 0.7.

Editing transformation parameters

Moisture dependence of the half-life time

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Factor for the effect of depth on transformation

The factor that accounts for the change in the rate of transformation with increasing depth must be introduced for each soil layer. This is soil profile and compound dependent. The default values have been taken from a literature review by Boesten and Van der Linden (1991). Additional information can be found in Walker et al. (1989, 1992).

Editing transformation parameters

Theory on first-order transformation

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Transformation of pesticide in soil
Transformation rate of pesticide in soil

The rate of pesticide transformation in soil depends on temperature, soil moisture content and depth in soil:

where ft () is the factor for the effect of temperature, fm () is the factor for the effect of soil moisture, fd () is the factor for the effect of depth in soil, and kt,r (1/d) is the rate coefficient at reference conditions, which is calculated from:

where DT50,r (d) is the half-life of the pesticide in the well-moistened plough layer at reference temperature.

Editing transformation parameters

Temperature dependence of the half-life time

Moisture dependence of the half-life time

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The Arrhenius equation

The effect of temperature on the pesticide transformation rate is described by the Arrhenius equation:

where Ea (J/mol) is molar activation energy, R (J/(mol K)) is the molar gas constant, and T (K) is temperature. The Arrhenius equation is assumed to be valid from 0 to 35 deg C. Above 35 deg C, the factor for the effect of temperature is kept constant. At temperatures below zero, the factor for the effect of temperature is set to zero (Jarvis, 1994). This implies that no pesticide transformation is simulated in frozen soil.

Editing transformation parameters

First-order rate transformation

Moisture dependence of the half-life time

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The effect of soil water on transformation

The equation for the effect of soil water on transformation reads (Walker, 1974):

where è (m3/m3) is volume fraction of soil water, B (-) is empirical factor for the effect of soil moisture, and the suffix fc refers to field capacity.

Editing transformation parameters

First-order rate transformation

Temperature dependence of the half-life time

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The relative diffusion coefficient
The diffusion coefficient in water

The coefficient of pesticide diffusion in the liquid phase is calculated from the diffusion coefficient in pure water and a relative diffusion coefficient. The diffusion coefficient in pure water is temperature dependent. Therefore, the temperature at which the diffusion coefficient was measured or estimated must be provided. The diffusion coefficient can be estimated from the molecular structure of a compound using the method described by e.g. Reid and Sherwood (1966). The value of the diffusion coefficient in water at 20  deg C will be approximately 4.3E-5 m2/d for compounds with a molar mass of 200 g/mol (Jury et al., 1983). This is also the default value in PEARL. Notice that this value is slightly different from the value in the old Dutch standard scenario, which was 4E-5 m2/d.

Editing diffusion coefficients

Transport in the liquid phase.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The diffusion coefficient in air

Transport of a compound in the gas phase is described with Fick's law, which requires the coefficient for diffusion in the gas phase. This coefficient is calculated from the diffusion coefficient in air and a relative diffusion coefficient. The diffusion coefficient in air is temperature dependent. Therefore, the temperature at which the diffusion coefficient was measured or estimated must be provided together. The diffusion coefficient can be estimated from the molecular structure of a compound using the method described by e.g. Reid and Sherwood (1966). The value of the diffusion coefficient in air at 20  deg C will be approximately 0.43 m2/d for compounds with a molar mass of 200 g/mol (Jury et al., 1983). This is also the default value in PEARL. For some compounds, particularly soil fumigants, the coefficients for diffusion in air are substantially higher than the default value. Van Den Berg (1992) estimated the coefficient for the diffusion of 1,3-dichloropropene in air at 20 deg C to be 0.69 m2/d.

Editing diffusion coefficients

Transport in the gas phase.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The convection dispersion equation

Transport of the pesticide in the liquid phase of the soil is described by an equation including convection, dispersion and diffusion:

where Jp,L (kg m2 d1) is the mass flux of pesticide in the liquid phase, q (m3 m2 d1) is the soil water flux, Ddis,L (m2 d1) is coefficient of pesticide dispersion in the liquid phase, z (m) is vertical position, and Ddif,L (m2 d1) is the coefficient of pesticide diffusion in the liquid phase. The dispersion coefficient is taken to be proportional to the soil water flux:

with Ldis,L (m) as the dispersion length. The diffusion of pesticide in the liquid phase is described by Fick’s law. The coefficient for diffusion of pesticide in the liquid phase is calculated by:

where æL (-) is the relative diffusion coefficient in the liquid phase, and Dw (m2 d1) is the coefficient of pesticide diffusion in pure water.

Soil water transport

The diffusion coefficient in pure water

The relative diffusion coefficient

Editing diffusion coefficients

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The relative diffusion coefficient

The relative diffusion coefficient is a function of the volume fraction of liquid in soil. PEARL offers three methods do describe this function. By default, the function proposed by Millington and Quirk (1960) is used:

where è (m3 m3) is the volume fraction of liquid, ès (m3 m3) is the volume fraction of liquid at saturation, and aM,L () and bM,L () are empirical parameters. The second type of equation is the one used by Currie (1960):

where aC,L () and bC,L () are empirical coefficients. The third equation is suggested by Troeh et al. (1982). In this approach, diffusion in the liquid phase is taken to be zero in a range of (low) volume fractions of water. In this range, the water-filled pores are assumed to be discontinuous:

where aT,L  (m3 m3) is the volume fraction of water at which the water phase becomes continuous, and bT,L  () is an empirical parameter.

The diffusion coefficient in water

Transport in the liquid phase

Transport in the gas phase

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The diffusion coefficient in water

The value of the diffusion coefficient in water is temperature dependent, mainly because the viscosity of water depends on the temperature. In PEARL, the theoretically derived Stokes-Einstein equation (Tucker and Nelken, 1982) is approximated by:

where T (K) is temperature, Tr (K) is reference temperature, and Dw,r (m2 d1) is the diffusion coefficient in water at reference temperature. See Leistra et al (2000) for details.

The relative diffusion coefficient

Transport in the liquid phase

Editing diffusion coefficients

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Transport in the gas phase

Transport of pesticide in the gas phase is described by Fick’s law:

where Jp,g (kg m2 d1) is mass flux of pesticide in the gas phase, and Ddif,g (m2 d1) is coefficient of pesticide diffusion in the gas phase. The coefficient for diffusion of pesticide in the gas phase is calculated by:

where æg (-) is the relative diffusion coefficient in the gas phase, and Da (m2 d1) is the coefficient of pesticide diffusion in air. The relation between Da and temperature is described by:

where Da,r (m2 d1) is the diffusion coefficient in air at reference temperature. The relative diffusion coefficient is a function of the volume fraction of the gas phase. It is calculated analogous to the relative diffusion coefficient in the liquid phase

Editing diffusion coefficients

Transport in the liquid phase

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Guidance on substance uptake parameters

The only parameter in the equation for uptake of substances is the coefficient for the uptake by plant roots, fu. This coefficient is sometimes known as the transpiration stream concentration factor, F. For non-ionic compounds, this factor can be estimated from the octagonal-water partitioning coefficient as described by Briggs et al. (1982). For these compounds, this factor will be between 0 and 1. For ionic compounds no reliable estimation methods exist and the factor may be greater than 1. For example, Shone and Wood (1974) found a value of 3 for the 2,4-D anion. The default value in PEARL is 0.5, which is the average of values reported in Briggs et al. (1982).

The Corps tab of the Surseances form

Theory on uptake by plant roots

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Canopy processes

Canopy processes must be simulated if:

•	The pesticide is applied to the canopy

•	The deposition is simulated

•	a pesticide is added to sprinkler irrigation.

The most important processes and aspects are:

•	Initial distribution over plant canopy and soil surface

•	The Dissipation at the crop canopy

•	The Wash-off from the crop canopy

•	A mass balance

Initial distribution

When a pesticide is sprayed on a field grown with plants, the nominal dosage has to be distributed over the plant canopy and the soil surface:

and

where Ad,f (kg/m2) is the areic mass of pesticide applied to the field, Ad,p (kg/m2) is the areic mass of pesticide applied to the crop canopy, Ad,s (kg/m2) is the areic mass of pesticide deposited on the soil, and SC (-) is the fraction of the soil surface covered by the crop. Methods are being developed for more targeted spraying on plants or on the soil surface, so the soil cover fraction may not be appropriate. In this particular case, the fraction of the dosage that is deposited onto the crop canopy can be introduced by the user.

Please note: All areic quantities are expressed on the basis of field surface.

Dissipation

The following processes are described at the plant surface:

•	Volatilisation into the air

•	Penetration into the plant

•	Transformation at the plant surface.

These processes are described by first-order kinetics:

where Rdsp (kg m2 d1) is the areic mass rate of dissipation of pesticide at the plant surface, kv,p (1/d) is rate coefficient for volatilisation, kp,p (1/d) is rate coefficient for penetration, kt,p (1/d) is rate coefficient for transformation at the plant surface, and Ap (kg/m2) is areic mass of pesticide at the crop canopy. Alternatively, the user can introduce an overall dissipation rate coefficient, kdsp (1/d) for the three processes.

Pesticide wash-off

The areic mass rate of pesticide wash-off is taken to be proportional to the canopy drip flux:

where Rw,p (kg m2 d-1) is the areic mass rate of pesticide wash-off from the crop canopy, wp (1/m) is an empirical wash-off factor, P (m/d) is precipitation, and Pi (m/d) is intercepted water.

Mass balance

The following mass balance applies for the crop canopy:

Applications

Deposition

Irrigation

Background on application schemes

The Crops tab of the Substances form

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Uptake of pesticides

The uptake of pesticide by plant roots is described by the equation:

where Ru (kg m-3 d-1) is volumic mass rate of pesticide uptake, Ru,L (m3 m3 d1) is volumic volume rate of water uptake, and fu (-) is an empirical transpiration stream concentration factor.

The Crops tab of the Substances form

Soil water uptake

Transport of substances

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Inital and boundary conditions
Transformation schemes

Transformation of pesticides may lead to reaction products (daughters) that may show a certain degree of persistence and mobility in soils. For this reason, the formation and behaviour of the most important daughters is included in PEARL. The first step in the definition of the reaction scheme is to set up the list of compounds that will be considered. The second step is the definition of the pathways of pesticide transformation. Consider the example. This example shows that a compound may transform into various products and that they may be formed from more than one precursor compound.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The transformation scheme of atrazine

Consider the transformation scheme of atrazine:

We start building the transformation scheme for the parent pesticide, atrazine. 33% of atrazine is transformed into hydroxy-atrazine (AT-OH) and 21% in desethyl-atrazine (DEA). To introduce this scheme, go to the substance form, select substance 'Atrazine' and press 'transformation scheme'. Transformation products can be added by using the + button in the navigator of the browse box. Pick 'AT-OH' from the 'to substance' list. Fill in 0.33 in the 'Fraction transformed' field. Then select 'DEA' and fill in 0.21. Notice that it is not necessary that the sum of the fractions is equal to one.

The transformation scheme for the other products should be introduced in an analogous way. To introduce the reaction scheme for AT-OH, first go the substance form, select AT-OH in the browse box, then press 'transformation scheme'. You will see that in this case, the transformation scheme is already completed (AT-OH does not have relevant metabolites), so no further action is required. The same applies for desethyl-atrazine.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Transformation rate parameters in the case of non-equilibrium sorption

Commonly reported half-lives refer to the total amount of pesticide in soil. As PEARL assumes that transformation of pesticide occurs in the equilibrium domain only, a different experimental set-up must be used to obtain the half-life of pesticides that show desorption/sorption kinetics. In this new experimental set-up, the following two quantities must be measured as a function of time:

•	the total mass of pesticide, Mp

•	the concentration of pesticide in the liquid phase, cL

In addition to the transformation experiment, a batch-type sorption experiment should be carried out.

Using this experiment, a simple model describing the processes during the experiment and the PEST parameter optimisation tool (Doherty et al., 1994), the following parameters can be obtained:

•	The first-order rate coefficient for transformation, kt (1/d)

•	The desorption rate coefficient, kd (1/d)

•	The ratio of sorption coefficients KF,Ne/KF,Eq.

•	The molar activation energy for transformation, Ea (J/mol), provided the incubation experiments were carried out at different temperatures.

The simple model, PEARLNEQ, is provided with the PEARL model. PEST is not distributed with the PEARL package but should be ordered directly from a commercial supplier (e.g. http://www.parameter-estimation.com; a demo can be found at http://www.parameter-estimation.com/html/pest_demo.html. A pdf file is added to the corresponding directory, containing a manual.

Transformation rate parameters in the case of non-equilibrium sorption

Theory on non-equilibrium sorption

The three-phase system

Transformation

Example

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Example
Example of obtaining transformation rate parameters

As an example of obtaining transformation rate parameters in the case of non-equilibrium sorption, we used the bentazone incubation study described by Boesten and van der Pas (1999). They simultaneously measured the decline of the total amount of bentazone in moist soil and of the pore water concentration in soil for about 400 d. The experiments were carried out at 5 deg C and 15  deg C. In a separate experiment, they measured the sorption of bentazone via shaking with a soil suspension for 24 h. We assume that the shaking period for the soil suspension experiment was long enough to obtain equilibrium at the equilibrium sites and that it was short enough to ignore sorption to the non-equilibrium sites. Boesten and Gottesbüren (2000) fitted the equilibrium sorption isotherm and found KFEq = 0.10 L/kg and N = 0.82. With these parameter values, kt at 20 deg C, Ea, KFNe/KFEq and kd were optimised with the PEARLNEQ-PEST combination. The figure shows the lines that result from the fitting procedure.

The figure shows that the decline of both the mass in soil and the concentration in the liquid phase could be described well with the PEARLNEQ-PEST combination. The table below shows the fitted parameter values and their 95 % confidence limits. The fitted parameter values compare well to results from the studies by Boesten and Gottesbüren (2000) and Tiktak et al. (1998).

Fitted parameter values for the desorption rate constant, pesticide transformation half-life, molar-activation energy and the ration KF,Ne/KF,Eq obtained from the bentazone incubation experiments

Parameter	Unit	Estimated value	95 % confidence limits

Lower limit	Upper limit

KFNe/KFEq	(-)	0.728	0.305	1.152

Kd	(1/d)	0.0193	0.0083	0.0304

DT50	(d)	13.73	9.45	18.01

Ea	(kJ/mol)	110	98	122

Theory on non-equilibrium sorption

The three-phase system

Transformation

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Lateral dischrage of pesticide
Lateral discharge of pesticide

The rate of water discharged by the tile-drainage system is calculated by the hydrological submodel. The lateral discharge of pesticides is taken proportional to the water fluxes discharged by the tile-drainage system:

where Rd (kg m3 d1) is volumic mass rate of pesticide discharge, and Rd,L (m3 m3 d1) is volumic volume rate of water discharge. The equation implies that it is assumed that concentration gradients in the lateral direction are negligible (i.e. no diffusion/dispersion).

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Guidance on deriving transformation fractions

Background

Example

Background

PEARL needs data on the molar fractions of the parent transformed to each of its products.

•	The transformation fractions reported in a pesticide registration dossier may be based on masses (kg) or on molar fractions.

Molar fractions must be specified relative to the precursor in each reaction (which can be the parent or one of the products). The molar fractions for the transformation of a compound must add up to one.

•	Pesticide registration dossiers often state the transformation scheme of a compound, including the amounts of transformation products formed, relative to the initial amount of the pesticide. For relatively simple transformation schemes (parent and first generation daughters only) the molar fraction data can be roughly estimated from the results. For second (or higher) order generation transformation products the molar fractions usually have to be recalculated from the original data.

If dossier data are missing, the transformation fraction must be obtained by fitting the reaction scheme to the experimental data.

•	Graphical method for estimating transformation fractions may lead to erroneous results. In this methodology, the peak values of the transformation curves are used. This leads to erroneous results, as shown in the example. Instead, transformation fractions must be obtained by fitting the reaction model (scheme) to the experimental data. Several software packages, e.g. TOPFIT and SIMUSOLV are commercially available for this purpose.

Example

The accompanying figure shows the transformation curves of a pesticide with two metabolites. The transformation route is an ordinary chain reaction (see figure). The registration dossier of this pesticide states half-lives of 2.4, 22 and 48 days for the  parent, the first metabolite and the second metabolite, respectively. Transformation fractions are 0.76 for the first metabolite and 0.5 for the second metabolite, both relative to the parent. The transformation fraction of the second reaction must be recalculated, because the fraction should be introduced into PEARL relative to the first metabolite. Therefore, 0.658 (=0.5/0.76) should be used for the second reaction in the transformation table of PEARL. If data are calculated from experimental results one must be careful; if the results are expressed as mass versus time, data should be corrected for the molar masses.

From the example it becomes clear that the graphical method for estimating transformation fractions may lead to erroneous results. In this methodology, the peak values of the curves are often incorrectly used as an approximation of the transformation fractions. In this case, transformation fractions of 0.61 and 0.44 (=0.27/0.61) could be derived from the figure. As these values are far below the real values, we strongly recommend to use the parameter estimation method.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The initial groundwater level

The initial groundwater level (m). This variable is not used if the option for the lower boundary condition is set to 'Groundwater Level as a function of time'. The initial groundwater level must be between 0 and 50 m.

Back to the main form

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Swap control

This tab contains control parameters for the hydrological model SWAP. We recommend not to change these parameters, unless you are very familiar with hydrological modelling. Specify the following parameters:

•	The minimum and maximum time-steps (d) of the hydrological model. These variables  determine the minimum and maximum time-steps in the SWAP model. The model will look for the optimal time step between the pre-set limits. Making the time-step too large could lead to instability, while making it too small will increase the computation time substantially.

-	The minimum time-step must be between 1E-8 and 0.1 days.

-	The maximum time-step must be between 0.01 and 0.5 days.

•	The relative tolerance of the SWAP iteration procedure (-). This variable defines the accuracy of the hydrological simulations. Choosing the tolerance too large could introduce a significant numerical water balance error. The tolerance must be between 1E-5 and 0.01.

•	The tolerance for the groundwater level (m). This variable determines the maximum change of the groundwater level in each individual time step. The tolerance should be between 1E-7 and 100 m.

•	The maximum number of iterations (-). Its value is between 2 and 1E6. This variable determines the maximum number of iterations. In some extremely non-linear situations, SWAP may not be able to find a solution. In these cases, a water balance error may occur. It is therefore extremely important that the water balance error is checked.

If you use PEARL for higher-tier assessments, always check the numerical water balance error. A mass balance error larger than 5 mm is usually considered to be unacceptable. See User Defined Graphs.

•	The Hydrology Option. The following options are available:

-	Skip SWAP run if  SWAP output is available. This option saves computation time if simulations are carried out for multiple substances at a site.

-	Assumes that SWAP has already been run; a pfo file must be provided.

-	Runs SWAP and then PEARL. SWAP will always be run, even if a pfo file is already present.

-	Runs SWAP only (output in PEARL format). This option is interesting when testing or calibrating the hydrological model, without (yet) running the pesticide part.

-	Creates only input for SWAP. Input files are generated for SWAP, but none of the models are run.

Be careful in using the first option. If you have changed parameters in the hydrological model - the SWAP output file is out-of-date!

•	The Hysteresis Option. SWAP has the possibility of considering hysteresis. This option can be set to the following values:

-	No: Hysteresis is not considered. This is the default value

-	Start with drying

-	Start with wetting

•	Minimum pressure head to switch between drying and wetting (cm). The default value is 0.2 cm.

Simulation of hystersis also requires that the user specificies to values for the Van Genuchten parameter alpha, i.e. one for the main wetting curve and one for the main drying curve. The parameter values must be introduced into the building-blocks form.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Hysteresis

Hysteresis refers to the non-uniqueness of the retention curve due to repeated wetting and drying. Gradual desorption of an initially saturated soil sample gives the main drying curve of the retention curve, while slow absorption of an initially dry sample results in the main wetting curve. In the field, wetting and drying occurs in numerous cycles, resulting in so-called drying and wetting scanning curves, lying between the main drying and the main wetting curves. SWAP uses linear scaling of the main wetting and drying curves to obtain the scanning curves. Because it is assumed that the conducitivity function is unique, only one additional parameters has to be specificied, i.e. Van Genuchten parameter alpha of the main wetting curve.

Simulation of hysteresis is primarily important when frequent changes occur from wetting to drying conditions. The effects are most pronounced if the soil surface is ponded. This occurs primarily at events with a large precipitation/irrigation flux in relatively dry soils.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Project reports

PEARL has the option to summarize the most important model outputs of an entire project. After pressing the Reports button on the main form, select 'Report of all runs in project'. The results will be shown in an database view. The following options exist:

•	The user can sort the columns by dragging;

•	The data can be viewed using an internet browser;

•	The data can be copied to the clipboard and then be imported in a text or EXCEL sheet.

FOCUS report

Dutch registration procedure reports

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© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


FOCUS Reports

The FOCUS report starts with a header, which contains some general information about the run. Then the following information is given for each substance:

•	The most important substance properties.

•	A summary of the 20 FOCUS periods, including

-	Water percolated below the target depth (mm)

-	Mass of substance leached below the target depth (kg/ha)

-	Average substance concentration in water at the target depth (ug/L)

•	The 80th percentile of the average concentration of substance in water at the target depth. This is the FOCUS target quantity, to be reported when submitting a pesticide for registration.

•	The FOCUS period containing the 80th percentile.

The depth of the FOCUS target layer can be set in the output control tab.

A more comprehensive summary, including annual water and substance balances can be accessed through the View menu of the main form (View - Summary Output file)

Example

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Example of a FOCUS report

* PEARL REPORT: Leaching
* Start date      :   01-Jan-1901
* End date        :   31-Dec-1926
* Target depth    :   1.00 m
* Annual application to the soil surface at 31-Oct; dosage =     1.0000 kg.ha-1

* Leaching summary for compound D
* Molar mass (g.mol-1)                                :    300.0
* Saturated vapour pressure (Pa)                      :  0.1E-03; measured at (C)  20.0
* Solubility in water (mg.L-1)                        :  0.9E+02; measured at (C)  20.0
* Half-life (d)                                       :     20.0; measured at (C)  20.0
* Kom (coef. for sorption on organic matter) (L.kg-1) :     35.0
* KF    (overall sorption coefficient of the target layer) (L.kg-1) :     0.469
* Freundlich exponent (-)                             :     0.90
* ----------------------------------------------------------------------------------------------------------------------------------
* Period        From          To               Water percolated              Substance leached              Average substance
* number                                below target depth (mm)     below target depth (kg/ha)         concentration in water
*                                                                                                      at target depth (ug/L)
* ----------------------------------------------------------------------------------------------------------------------------------
   1     01-Jan-1907 31-Dec-1907                        125.702                      0.0021305                          1.695
   2     01-Jan-1908 31-Dec-1908                         58.706                      0.0000991                          0.169
   3     01-Jan-1909 31-Dec-1909                        234.366                      0.0018533                          0.791
   4     01-Jan-1910 31-Dec-1910                        286.004                      0.0049037                          1.715
   5     01-Jan-1911 31-Dec-1911                        243.885                      0.0037241                          1.527
   6     01-Jan-1912 31-Dec-1912                        468.451                      0.0180763                          3.859
   7     01-Jan-1913 31-Dec-1913                        513.753                      0.0173363                          3.374
   8     01-Jan-1914 31-Dec-1914                        234.722                      0.0051277                          2.185
   9     01-Jan-1915 31-Dec-1915                        298.584                      0.0049456                          1.656
  10     01-Jan-1916 31-Dec-1916                        347.058                      0.0081481                          2.348
  11     01-Jan-1917 31-Dec-1917                        227.062                      0.0035370                          1.558
  12     01-Jan-1918 31-Dec-1918                        192.342                      0.0026149                          1.360
  13     01-Jan-1919 31-Dec-1919                        297.817                      0.0071151                          2.389
  14     01-Jan-1920 31-Dec-1920                        340.362                      0.0075250                          2.211
  15     01-Jan-1921 31-Dec-1921                        164.574                      0.0014145                          0.860
  16     01-Jan-1922 31-Dec-1922                         64.370                      0.0000271                          0.042
  17     01-Jan-1923 31-Dec-1923                        273.881                      0.0017812                          0.650
  18     01-Jan-1924 31-Dec-1924                        194.343                      0.0019339                          0.995
  19     01-Jan-1925 31-Dec-1925                        391.219                      0.0095410                          2.439
  20     01-Jan-1926 31-Dec-1926                        454.092                      0.0136039                          2.996

* The average concentration of D closest to the 80th percentile is      2.413937 ug/L

* End of PEARL REPORT: Leaching

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Use graph templates

In this form, you can select  an existing graph template. Graph templates can be used ff you want to make graphs with pre-set axes and titles. Also, if you want to plot monitoring data in combination with simulation results, you have to use templates. Templates must be created before entering this form. To do this, select Graphs from the main menu, and then 'Graph templates'. Now:

•	Create a new template

•	Fill in the templates form

•	Close the form to return to the main form

To learn more, read the Graph templates page.

Graph templates

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Control of user-defined graphs

The User defined Graphs form is accessible with the Graphs, User defined button at the main form. The form consists of four parts:

•	In the upper part you can browse the categories of available variables.

•	In the lower-left part of the form you can browse the individual variables within a category

•	In the top-right part of the form you can select and browse the depths.

•	In the lower-right part of the form you can select and browse substances.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Categories of variables available for graphs
Categories of variables available for output

PEARL has the following categories of output variables available:

•	Pearl Soil balance:

Mass balance of the soil system, which includes variables like the areic mass of transformation and the areic mass of pesticide in the soil system.

•	Pearl concentrations:

Concentration of pesticide in the various phases of the soil system, such as the substance concentration in the liquid phase.

•	Pearl Crop balance:

Mass balance of pesticide at the crop canopy

•	Pearl fluxes:

Mass fluxes of pesticides.

•	Pearl general:

Miscellaneous variables, such as the time-step.

•	Swap Soil fluxes:

Volume fluxes of water, such as the soil water flux

•	Swap general:

Miscellaneous variables, such as the groundwater level and the Leaf Area Index.

•	Swap states:

State variables of the hydrological model, such as the soil water content.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Selecting of variables for graphing
Selecting variables for graphing

In this part of the form, you can select variables for graphing:

•	Select and deselect variables individually by double clicking

•	Deselect groups of variables using the Clear All Variables.

Please notice that you cannot mix variables that are depth dependent with variables that are not depth dependent.

You will only see those variables that are selected in the Detailed Output Control form.

If one of the wanted variables is missing, go to this form, select for output and re-run the model.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Output depths

Here, you select depths for which you want to make graphs. The depths shown are the nodal depths (i.e. the middle of a numerical compartment).

Please notice that you cannot mix variables that are depth dependent with variables that are not depth dependent.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Substances

Here, you can select one or more substances.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Example of a detailed output file

The example shows part of the output file, which was produced with the following settings:

•	Format of the time column was set to 'number of days since the start of simulation'

•	Format for reals was set to G12.4

•	Intended depths were set to 0.25 and 0.50 m. These depths are in the 0.225-0.250 m and 0.475-0.500 m layers with nodal points situated at 0.2375 m and 0.4875 m depth. These depths are listed in record Z, directly after the header.

•	Output was requested for the variables Tem, GrwLev, FlvLiqPrc, ConSys, ConSysEql, ConLiq and FlmLiq.

 ------------------------------------------------------------------------------

 ######                                ###

  ##  ##                                ##

  ##  ##   #####    #####   ## ###      ##

  #####   ##    #       #    ### ##     ##

  ##      #######  ######    ##         ##

  ##      ##       #   ##    ##         ##

 ####      #####   #### ##  ####       ####  (c) RIVM/Alterra

 Pesticide Emission Assessment at Regional and Local scales

 ------------------------------------------------------------------------------

 RIVM                      Alterra

 PO BOX 1                  PO BOX 47

 3720 BA Bilthoven         6700 AA Wageningen

 the Netherlands           the Netherlands

 ------------------------------------------------------------------------------

    0.000                              Z   0.2375      0.4875

… … …

  192.000 10-Jul-1960                Tem   14.3500     13.7900

  192.000 10-Jul-1960             GrwLev   0.2200E-01

  192.000 10-Jul-1960          FlvLiqPrc   0.1060E-01

  192.000 10-Jul-1960        ConSys_pest   0.8934E-07  0.1345E-19

  192.000 10-Jul-1960     ConSysEql_pest   0.8934E-07  0.1345E-19

  192.000 10-Jul-1960        ConLiq_pest   0.5202E-08  0.9874E-22

  192.000 10-Jul-1960        FlmLiq_pest  -0.1409E-09 -0.2740E-23

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


References

A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z

A

Allen, R.G., M.E. Wright and R.D. Burman. 1989. Operational estimates of evapotranspiration. Agron. J. (81):650-662.

Ashby, M., A.J. Dolman, P. Kabat, E.J. Moors and M.J. Ogink-Hendriks. 1996. swap S version 1.0. Technical Reference Manual. Technical Document 42. SC-DLO, Wageningen, The Netherlands.

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Bakker, J.W., F.R. Boone and P. Boekel. 1987. Diffusie van gassen in grond en zuurstofdiffusiecoëfficiënten in Nederlandse akkerbouwgronden.ICW Rapport 20. Wageningen, The Netherlands, pp. 44.

Boekhold, A.E., H. van den Bosch, J.J.T.I. Boesten, M. Leistra, F.A. Swartjes and A.M.A. van der Linden. 1993. Validation of the PESTLA model: Definitions, objectives and procedure. rivm report no. 715802001, rivm, Bilthoven, the Netherlands.

Boesten, J.J.T.I. 1986. Behavior of pesticides in soil: Simulation and experimental assessment. Ph.D. thesis, Wageningen Agricultural University, Wageningen, the Netherlands.

Boesten, J.J.T.I. 1991. Sensitivity analysis of a mathematical model for pesticide leaching to groundwater. Pestic. Sci. (31):375-388.

Boesten, J.J.T.I. 2000. Modeler subjectivity in estimating pesticide parameters for leaching models using the same laboratory data set. Agric. Water Mgmt, (44):389-409.

Boesten, J.J.T.I. and B. Gottesbüren. 2000. Testing pestla by two modelers for bentazone and ethoprophos in a sandy soil. Agric. Water Mgmt (44):283-305.

Boesten, J.J.T.I., and A.M.A. van der Linden. 1991. Modeling the influence of sorption and transformation on pesticide leaching and persistence. J. Environ. Qual. (20):425-435.

Boesten, J.J.T.I., and L.J.T. van der Pas. 1983. Test of some aspects of a model for the adsorption/desorption of herbicides in field soil. Aspects of Applied Biology (4):495-501.

Boesten, J.J.T.I., and L.J.T. van der Pas. 1997. Movement of water, bromide ion and the pesticides ethoprophos and bentazone measured in a sandy soil in Vredepeel (the Netherlands). SC-DLO report no. 122, Wageningen, the Netherlands.

Boesten, J.J.T.I., and L.J.T. van der Pas. 2000. Movement of water, bromide ion and the pesticides ethoprophos and bentazone in a sandy soil: Description of the Vredepeel data set. Agric. Water Mgmt (44):21-42.

Boesten, J.J.T.I. and L. Stroosnijder. 1986. Simple model for daily evaporation from fallow tilled soil under spring conditions in a temperate climate. Neth. J. Agric. Sci. (34):75-90.

Bollen, M.J.S., F.H.W.M. Bekhuis, R. Reiling, and E. Scheper. 1995. Towards a spatial pattern of the vulnerability of soil and groundwater. rivm report no. 711901012, Bilthoven, the Netherlands. (In Dutch.)

Bowman, B.T. and W.W. Sans. 1985. Effect of temperature on the water solubility of insecticides. J. Environ. Sci. and Health. (B20):625-631.

Bouten, W. 1992. Monitoring and modeling forest hydrological processes in support of acidification research. Ph.D. thesis, University of Amsterdam, the Netherlands, p.218.

Braden, H. 1985. Ein Energiehaushalts- und Verdunstungsmodell für Wasser und Stoffhaushaltungsuntersuchungen landwirtschaftlich genutzer Einzugsgebiete. Mitteilungen Deutsche Bodenkundliche Geselschaft (42):294-299.

Briggs, G.G., R.H. Bromilow, and A.A. Evans. 1982. Relationships between lipophilicity and root uptake and translocation of non-ionized chemicals by barley. Pestic. Sci. (13):495-504.

Brouwer, W.W.M., J.J.T.I. Boesten, J.B.H.J. Linders and A.M.A. van der Linden. 1994. The behavior of pesticides in soil: Dutch guidelines for laboratory studies and their evaluation. Pesticide Outlook (5):23-28.

C

Calvet, R., M. Tercé, and J.C. Arvieu. 1980. Adsorption des pesticides par les sols et leurs constituents. III. Characteristiques générales de l'adsorption des pesticides. Ann. Agron. (31):239-257.

Carsel, R.F. and R.S. Parrish. 1988. Developing joint probability distributions of soil water characteristics. Water Resour. Res. (22):211-227.

Currie, J.A. 1965. Diffusion within soil microstructure: A structural parameter for soils. J. Soil Sci. (16):279-289.

D

De Vries, D.A. 1963. Thermal properties of soils. In: W.R. Van Wijk (ed). Physics of the Plant environment. North-Holland Publ. Company, Amsterdam, The Netherlands, p. 210-235.

E

F

Feddes, R.A. 1987. Crop factors in relation to Makkink reference-crop evapotranspiration. In: Evapotranspiration and weather. Proceedings and Information (39):33-45. TNO Committee on Hydrological Research, The Hague, the Netherlands.

Feddes, R.A., P.J. Kowalik and H. Zaradny. 1978. Simulation of field water use and crop yield. Simulation Nomographs. Pudoc. Wageningen, The Netherlands. pp. 189.

FOCUS Soil Modeling Working Group. 1997. Soil Persistence models and EU registration. DG VI. European Commission, Doc. 7617/VI/96, Brussels, pp. 74.

FOCUS, 2000. Focus groundwater scenarios in the EU plant protection product review process. Report of the FOCUS Groundwater Scenarios Working Group, EC Document Reference Sanco/321/2000, pp. 197.

FOCUS, 2009. Assessing Potential for Movement of Active Substances and their Metabolites to Ground Water in the EU. Report of the FOCUS Ground Water Work Group, EC Document Reference Sanco/???/2009 version 1, 594 pp.

Fontaine, D.D., R.G. Lehmann, and J.R. Miller, J.R. 1991. Soil Adsorption of Neutral and Anionic Forms of a Sulfonamide Herbicide, Flumetsulam. J. Environ. Qual. (20):759-762.

Freijer, J.I. 1994. Mineralization of hydrocarbons and gas dynamics in oil-contaminated soils. Ph.D. Thesis, University of Amsterdam, the Netherlands.

Freijer, J.I., A. Tiktak, S.M. Hassanizadeh, and A.M.A. van der Linden. 1996. PESTRASv3.1.: A one dimensional model for assessing leaching, accumulation and volatilization of pesticides in soil. rivm Report no. 715501007, Bilthoven, the Netherlands.

G

Goudriaan, J. 1977. Crop Meteorology: A simulation study. Simulation Nomographs, Pudoc, Wageningen, The Netherlands.

H

Hallberg, G.R. 1989. Pesticide pollution of groundwater in the humid United States. Agric. Ecosyst. Environ. (26):299-367.

Herkelrath, W.N., E.E. Miller, and W.E. Gardner, W.E. 1977. Water uptake by plants: II. The root contact model. Soil Sci. Soc. Am. J., (41):1039-1043.

Hornsby, G.H., R.D. Wauchope and A.E. Herner. 1996. Pesticide properties in the Environment. Springer Verlag, New York.

I

J

Jarvis, N. 1991. MACRO - A model of water movement and solute transport in macroporous soil. Monograph, Reports and dissertations, 9. Dept. of Soil Sci., Swedish Univ. Agric. Sci., Uppsala, Sweden, 58pp.

Jin, Y. and W.A. Jury. 1996. Characterizing the dependence of gas diffusion coefficient on soil properties. J. Environ Qual. (60):66-71.

Jury, W.A., D. Russo, G. Streile and H.E. Abd. 1990. Evaluation of volatilization by organic chemicals residing below the soil surface. Water Resour. Res. (26):13-20.

Jury, W.A., W.F. Spencer and W.J. Farmer. 1983. Behavior Assessment Model for trace organics in soil. I. Model description. J. Environ. Qual. (12):558-564.

K

Kroes, J.G., J.C. van Dam, J. Huygen, and R.W. Vervoort. 1999. User's Guide of swap version 2.0 Simulation of water flow, solute transport and plant growth in the Soil-Water-Atmosphere-Plant environment. SC-DLO technical document 53, Wageningen, The Netherlands, pp. 127.

L

Leij, F.J., W.J. Alves, M.Th. van Genuchten and J.R. Williams. 196. The UNSODA Unsaturated Soil Hydraulic Database. User's manual Version 1.0. Soil Salinity Laboratory, Riverside, CA.

Leistra, M., and J.J.T.I. Boesten. 1989. Pesticide contamination of groundwater in western Europe. Agric. Ecosyst. Environ. (26):369-389.

Leistra, M., and W.A. Dekkers. 1976. Computed leaching of pesticides from soil under field conditions. Water  Air Soil Pollut. (5):491-500.

Leistra, M., A.M.A. van der Linden, J.J.T.I. Boesten, A. Tiktak and F. van den Berg. 2000. PEARL model for pesticide behaviour and emissions in soil-plant systems. Description of processes. Alrterra report 013, Alterra, Wageningen, the Netherlands.

Linders, J.B.H.J. J.W. Jansma, B.J.W.G. Mensink, and K. Otermann. 1993. Pesticides: Benefaction or Pandora's Box? A synopsis of the environmental aspects of 243 pesticides.rivm report no. 679101014, Bilthoven, the Netherlands.

M

Makkink, G.F. 1957. Testing the Penman formula by means of lysimeters. J. Inst. Water Eng. (11):277-288.

Millington, R.J. and J.P. Quirk. 1960. Transport in porous media. In: F.A. van Beren et al. Trans. Int. Congress Soil Sci Soc. 7th. Volume 1. Madison, WI. Elsevier, Amsterdam. p. 97-106.

Monteith, J.L. 1965. Evaporation and environment. Proc. Symp. Soc. Exp. Biol., (19):205-234.

N

O

P

Q

R

Reid, R.S. and T.K. Sherwood. 1966. The properties of gases and liquids. McGraw-Hill, London, 646pp.

S

Shone, M.G.T. and A.V. Wood. 1974. A comparison of the uptake and translocation of some organic herbicides and a systematic fungicide by barley. J. Experimental Botany (25):390-400.

Smit, A.A.M.F., F. van den Berg and M. Leistra. 1997. Estimation method for the volatilization of pesticides from shallow soil. Env. Planning Bureau Series 2. Agricultural Research Department, Wageningen, The Netherlands, pp. 108.

T

Tiktak, A. 1999. Modeling Non-Point Source Pollutants in Soils. Applications to the Leaching and Accumulation of Pesticides and Cadmium. Ph.D. Thesis, University of Amsterdam, Amsterdam, The Netherlands, pp. 224.

Tiktak, A. 2000. Application of pesticide leaching models to the Vredepeel dataset. II. Pesticide fate. Agric. Water Mgmt (44):119-134.

Tiktak, A., and W. Bouten. 1992. Modeling soil water dynamics in a forested ecosystem. III: Model description and evaluation of discretization. Hydrol. Proc. (6):455-465.

Tiktak, A., A.M.A. van der Linden, and F.A. Swartjes. 1994. PESTRAS: A one dimensional model for assessing leaching and accumulation of pesticides in soil. rivm report no. 715501003, Bilthoven, the Netherlands.

Tiktak, A., A.M.A. van der Linden, and I. Leine. 1996a. Application of gis to the Modeling of Pesticide Leaching on a Regional Scale in the Netherlands. In: D.L. Corwin and K. Loague (Ed.). Application of gis to the Modeling of Non-Point Source Pollutants in the Vadose Zone. SSSA-Special Publication number 48, pp. 259-281.

Tiktak, A., A.M.A. van der Linden and R.C.M. Merkelbach. 1996b. Modeling pesticide leaching at a regional scale in the Netherlands. rivm report no. 715801008, rivm, Bilthoven, the Netherlands.

Tiktak, A., A.M.A. van der Linden, and L.J.T. van der Pas. 1998. Application of the Pesticide Transport Assessment Model to a field-study in a humic sandy soil in Vredepeel, the Netherlands. Pestic. Sci (52):321-336.

Tomlin, C. (Ed.). 1994. The Pesticide Manual. 10th Edition. Crop Protection Publications, Royal Soc. Chemistry, Cambridge, UK.

Troeh, F.R., J.D. Jabro and D. Kirkham. 1982. Gaseous diffusion equations for porous materials. Geoderma (27):239-253.

U

V

Vanclooster, M. and J.J.T.I. Boesten. 2000. Application of nine pesticide leaching models to the Vredepeel dataset. I. Water. solute and heat transport. Agric. Water Mgmt. (44):105-117.

Vanclooster, M., J.J.T.I. Boesten, M. Trevisan, C.D. Brown, Capri, Vacek, Eklo, B. Gottesbürren, Gouy and A.M.A. van der Linden. 2000. A European test of pesticide-leaching models: Methodology and major recommendations. Agric. Water Mgmt (44):1-3.

Van Dam, J.C., J. Huygen, J.G. Wesseling, R.A. Feddes, P. Kabat, P.E.V. van Walsum, P. Groenendijk and C.A. van Diepen. 1997. Theory of swap version 2.0. Simulation of water flow, solute transport and plant growth in the Soil-Water-Atmosphere-Plant environment. SC-DLO technical document 45, Wageningen, The Netherlands, pp. 167.

Van den Berg, F. 1992. Emission of fumigants from soil and dispersion in air. Ph.D. Thesis, Wageningen Agricultural University, Wageningen, The Netherlands.

Van den Berg, F. and J.J.T.I. Boesten. 1998. Pesticide Leaching and Accumulation model (pestla) version 3.4. Description and User's guide. SC-DLO technical document 43, Wageningen, The Netherlands, pp. 150.

Van den Bosch, H., and J.J.T.I. Boesten. 1994. Validation of the PESTLA model: Field test for leaching of two pesticides in a humic sandy soil in Vredepeel (the Netherlands). SC-DLO report no. 82, Winand Staring Center, Wageningen, the Netherlands.

Van der Linden, A.M.A. and J.J.T.I. Boesten. 1989. Berekening van de mate van uitspoeling en accumulatie van bestrijdingsmiddelen als functie van hun sorptiecoëfficiënt en omzettingssnelheid in bouwvoormateriaal. RIVM report no. 728800003, RIVM, Bilthoven, The Netherlands, pp. 51.

Van Genuchten, M.Th. 1980. A closed form for predicting the hydraulic conductivity of unsaturated soils. Soil Sci. Soc. Am. J. (44):892-898.

Van Genuchten, M.Th., F.J. Leij and S.R. Yates. 1991. The RETC code for quantifying the hydraulic functions of unsaturated soil. U.S. Salinity Laboratory, Riverside, CA.

Van Heemst, H.D.J. 1986. Crop phenology and dry matter distribution. In: H. van Keulen and J. Wolf (Ed). Modeling of Agricultural Production: Soil, Weather and Crops. p. 13-60.

Van Ommen, H.C., M.Th. van Genuchten, W.H. van der Molen, R. Dijksma, and J. Hulshof. 1989. Experimental and theoretical analysis of solute transport from a diffuse source of pollution. J. Hydrol. (105):225-251.

W

Walker, A. 1974. A simulation model for prediction of herbicide persistence. J. Environ. Qual. (3):396-401.

Wesseling, J.G. 1991. Meerjarige simulaties van grondwateronttrekking voor verschillende bodemprofielen, grondwatertrappen en gewassen met het model SWATRE. SC-DLO report 152, Wageningen, the Netherlands (In Dutch).

Wesseling, J.G., J.A. Elbers, P. Kabat and B.J. van den Broek. 1990. SWACROP - Instructions for input. Internal Communication 80, SC-DLO, Wageningen, The Netherlands, pp. 56.

Wösten, J.H.M., G.H. Veerman and J. Stolte. 1994. Water retention and hydraulic conductivity functions of top- and subsoils in the Netherlands: The Staring Series. SC-DLO Technical document no. 18, Wageningen, the Netherlands (In Dutch).

X

Y

Yates, S.R., M.Th. van Genuchten, A.W. Warrick and F.J. Leij. 1992. Analysis of measured, predicted and estimated hydraulic conductivity using the RETC computer program. Soil Sci. Soc. Am. J. (56):347-354.

Z

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Heat flow

Various processes such as pesticide transformation are affected by soil temperature. PEARL considers conductive heat transport in soil:

where Ch (J m-3 K-1) is the volumic heat capacity, T (K) is temperature, and ë (J m1 d1 K-1) is the thermal conductivity. The volumic heat capacity is calculated as the weighted mean of the heat capacities of the individual soil components (De Vries, 1963):

where èsand, èclay, èom and è (m3 m3) are the volume fractions of sand, clay, organic matter and water, å (m3 m-3) is the air-filled porosity, and Csand, Cclay, Com, Cw and Ca (J m3 K1) are the volumic heat capacities of the individual components. The table gives an overview of the volumic heat capacity for the individual soil components. The volume fractions of sand, clay and organic matter are calculated from the mass percentages of sand, clay and organic matter, which have to be specified in the Soil Building Blocks form. The thermal conductivity is calculated according to the procedure described by Ashby et al. (1996), which accounts for both soil composition and soil geometry. See the table.

Soil Building Blocks

Boundary conditions

The upper boundary condition for the soil heat-flow model is the daily average air temperature, Tair (K); the lower boundary condition is a zero-flux boundary condition. The heat flow equation is solved using a numerical method.

Heat capacity and thermal conductivity

Volumic heat capacity and thermal conductivity of the individual soil components (after Van Dam et al., 1997).

Component	Volumic heat capacity	Thermal conductivity

(J cm-3 K-1)	(J cm-1 K-1 d-1)

Sand	2.128	7603

Clay	2.385	2523

Organic matter	2.496	216

Water	4.180	492

Air (293 K)	1.212	22

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Model parameterization
Guidance on model parameterisation

In a ring-test of 9 European pesticide leaching models (Vanclooster et al. 2000), subjectivity in the derivation of model inputs was the major source of differences between model results (Tiktak, 2000; Boesten, 2000). An important recommendation was to provide the model-users with strict guidelines and additional tools for deriving model inputs. We therefore included this chapter, which gives an overview of methods to derive the most important model inputs.

In the pesticide registration procedure (e.g. Linders et al., 1994), several stages can be distinguished:

•	In first-tier assessments, the model is used to get a first indication of the leaching potential of a pesticide. To minimize user subjectivity during this stage, the model is used in combination with standardized scenario's (FOCUS, 2000). These scenario's are supported by PEARL.

•	In the second and higher tiers of the registration procedure, field studies and lysimeter experiments may become important. During this stage, the model should preferably be used in combination with on-site measured data. Guidelines for model parameterization follow below.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Overview of the pearl file

The pearl input file consists records. Each record contains the following fields:

•	An obligatory field containing the identifier

•	One or more fields containing the actual data

•	An optional field containing the dimension of the data

•	Comment fields

PEARL distinguishes the following type of records:

•	Numerical records

•	Option records

•	Date records

•	Soil properties

•	Compound properties

•	Crop properties

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Management

Repeat interval of applications

Application table

Tillage table

Listing

Repeat interval of applications

This section contains data on pesticide applications and tillage. First, a variable DelTimEvt  should be specified. This variable determines the repeat interval in years of the event table. If set to 2, for example, biennial applications are simulated. If set to NoRepeat, the application table will not be repeated.

Listing

Application table

The actual applications are specified in the Applications table.

•	The first column in this table contains the application date. Normal date format can be used, but the year is only required if DelTimEvt has been set to NoRepeat. You can also use relative dates; i.e. a number of dates relative to harvest or crop emergence. The format is xx-Emg-+/-yyy where xx is the crop sequence number, and yyy is the number of days. For example, 01-Emg-10 implies that the pesticide is applied 10 days before emergence of crop 1.

•	The second column contains the application type, which must have one of the following values:

•	Application to the soil surface (AppSolSur).

•	Incorporation (AppSolTil). If this option is chosen, the user must specify the tillage depth in the third column.

•	Injection (AppSolInj). If this option is chosen, the user must specify the injection depth in the third column.

•	Application to the crop canopy; fraction intercepted user specified (AppCrpUsr). The interception fraction must be specified in column 3.

•	Application to the crop canopy; fraction intercepted calculated on the basis of the soil cover fraction (AppCrpLAI).

Listing

Tillage table

Tillage events must be introduced into the TillageDates table. Column 1 contains the tillage date, column 2 contains the tillage depth. Please notice that the DelTimEvt switch operates on both the Applications and the TillageDates tables.

Listing

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Initial and boundary conditions

Initial conditions

Upper boundary conditions

Listing

Initial conditions

Both the mass content of pesticide in the equilibrium domain (CntSysEql) and the non-equilibrium domain of the soil system (CntSysNeq) should be specified in this section. The initial concentration is usually set to zero, i.e. the simulation starts with pesticide-free soil. Only in the case of previous pesticide applications, the initial pesticide concentration should be set unequal to zero. The intial mass content of metabolites cannot be specified.

Listing

Upper boundary condition

The upper boundary of the system is the crop canopy. This implies that pesticide entering the soil by deposition is always subject to dissipation at the crop canopy. Deposition fluxes should be specified in the FlmDep table. Deposition fluxes are linearly interpolated between two dates, so in the case of a constant deposition rate only two dates need to be specified (see the example). If OptIrr is set to Sprlinkler, dissipation at the crop canopy will be calculated. Please notice that only one concentration can be specified, which applies to all irrigation events.

Listing

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Control of daily output

Output as a function of time

Vertical profiles

Listing

Output as a function of time

In this section, the daily output is controlled. The following steps must be followed:

•	First specify whether the daily output file should be saved (OptDelOutput). If set to Yes, the daily output file will be removed. This option saves time if summary information is required only.

•	Specify the desired (fixed) output interval (record DelTimPrn). If set to zero, PEARL will calculate the output interval based on the begin and end date of the simulation. It is important to realize that PEARL generates averages over the print interval and not point values. This implies that a larger print interval generates a smoother picture.

•	Specify whether fluxes should be cumulated over the entire simulation period (PrintCumulatives).

•	Specify the desired format of the date (DateFormat) and the actual values in the output file (OutputFormat). The DateFormat can be set to DaysFromSta (print the number of days since the start of the simulation), DaysFrom1900 (print the number of days since 1-Jan-1900) or Years (print the number of years since the start of the simulation). To specify the output format, normal fortran notation should be used (see the example in appendix 3).

•	Specify the depths for which output is requested (OutputDepths)

•	Specify for each variable whether output is wanted or not (print_)

Listing

Output of vertical profiles

The user can specify a number of dates at which vertical profiles of the most important state variables are produced (table (VerticalProfiles).

Listing

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Listing of the PEARL input file

*-------------------------------------------------------------------------------

* INPUT FILE for PEARL 4.4.4

*

* This file is intended to be used by expert users.

* Figures between brackets refer to constraints (maximum and minimum values).

*

* Pearl e-mail address: pearl@pesticidemodels.nl

*

* (c) 2010 RIVM, PBL, Alterra

*-------------------------------------------------------------------------------

* Goto section:

* Section 0: Run identification and FOCUS version

* Section 1: Control section

* Section 2: Soil section

* Section 3: Weather and irrigation data

* Section 4: Boundary and initial conditions of hydrological model

* Section 5: Compound section

* Section 6: Management section

* Section 7: Crop section

* Section 8: Output control

*----------------------------------------------------------------------------------------

* Section 0: Run identification

*----------------------------------------------------------------------------------------

FOCUS                   OptReport             Type of report (No, FOCUS, DutchRegistration)

HAMBURG                 Location              Location identification

HAMB-S_Soil             SoilTypeID            Soil identification

HAMB-WCEREALS           CropCalendar          Crop calendar

pest                    SubstanceName         Substance name

FOCUS_EXAMPLE           ApplicationScheme     Application scheme

No                      DepositionScheme      Deposition scheme

No                      IrrigationScheme      Irrigation scheme

*----------------------------------------------------------------------------------------

* Section 1: Control section

* Description

*----------------------------------------------------------------------------------------

FOCUSPEARL     CallingProgram          Release type

4.4.4          CallingProgramVersion   Version number of the model, the GUI, and the database

* Time domain

6                 InitYears            Number of years in warming-up period

01-Jan-1901       TimStart             Begin time of simulation [01-Jan-1900|-]

31-Dec-1926       TimEnd               End time of simulation [TimStart|-]

0.0               AmaSysEnd (kg.ha-1)  Stop criterion - ignored if zero [0|-]

* SWAP control

0.001             ThetaTol (m3.m-3)   Tolerance in SWAP [1e-5|0.01]

Month             OptDelTimPrn        Option to set output interval

30                DelTimPrn  (d)      Print time step [0|-] - zero is automatic

No                RepeatHydrology     Repeat weather data: Yes or No

OnLine            OptHyd              OnLine, OffLine, Stationary, Only, Automatic

1E-7              DelTimSwaMin (d)    Minimum time step in SWAP [1d-8|0.1]

0.2               DelTimSwaMax (d)    Maximum time step in SWAP [0.01|0.5]

Yes               PrintCumulatives

1.0               GWLTol (m)          Tolerance for groundwater level

30                MaxItSwa            Maximum number of iterations in SWAP

No                OptHysteresis        Option to include hysteresis

0.2               PreHeaWetDryMin (cm) Minimum pressure head to switch drying/wetting

Yes               OptScreen            Option to write output to screen

No                OptPersistency       Option to assess persistency

All                OptSys              Option to define system (plant and soil or plant only)

No                OptPaddy             Option to assess paddy rice system

No                OptMacropore         Option to assess macropore flow

*----------------------------------------------------------------------------------------

* Section 2: Soil section

* Description

*----------------------------------------------------------------------------------------

HAMB-S_Soil SoilTypeID

HAMBURG Location

* The soil profile* Specify for each horizon:* Horizon thickness (m)* The number of soil compartments [1|500]* Nodes are distributed evenly over each horizontable SoilProfile

ThiHor NumLay

(m)

0.3      12

0.3      12

0.15     3

0.15     3

0.1      2

3.5      35

end_table

* Basic soil parameters* Specify for each soil horizon:

* Mass content of sand, expressed as a fraction of the mineral soil  (kg.kg-1)  [0|1]

* Mass content of silt, expressed as a fraction of the mineral soil  (kg.kg-1)  [0|1]

* Mass content of clay, expressed as a fraction of the mineral soil  (kg.kg-1)  [0|1]

* Organic matter mass content                                        (kg.kg-1)  [0|1]

* pH, pH measured in 0.01 M CaCl2 is preferred (see theory document) (-)        [1|13]

table  horizon SoilProperties

Nr     FraSand    FraSilt    FraClay      CntOm       pH

       (kg.kg-1)  (kg.kg-1)  (kg.kg-1)  (kg.kg-1)     (-)

1      0.683      0.245        0.072      0.026       6.4

2      0.67       0.263        0.067      0.017       5.6

3      0.962      0.029        0.009      0.0034      5.6

4      0.998      0.002        0          0           5.7

5      1          0            0          0           5.5

6      1          0            0          0           5.5

end_table

* Parameters of the Van Genuchten-Mualem relationships (B1 + O1)

* Specify for each soil horizon:

* The saturated water content     (m3.m-3)  [0|0.95]

* The residual water content      (m3.m-3)  [0|0.04]

* Parameter AlphaDry              (cm-1)    [1.d-3|1]

* Parameter AlphaWet              (cm-1)    [1.d-3|1]

* Parameter n                     (-)       [1|5]

* The saturated conductivity      (m.d-1)   [1.d-4|10]

* Parameter lambda (l)            (-)       [-25|25]

* New Staring Series - not used for standard scenario

table  horizon VanGenuchtenPar

Nr     ThetaSat    ThetaRes    AlphaDry    AlphaWet    n       KSat      l

       (m3.m-3)    (m3.m-3)    (cm-1)      (cm-1)     (-)     (m.d-1)   (-)

1      0.391       0.036       0.0149     0.0298     1.468    2.016     0.5

2      0.37        0.03        0.0126     0.0252     1.565    2.736     0.5

3      0.351       0.029       0.0181     0.0362     1.598    2.448     0.5

4      0.31        0.015       0.0281     0.0562     1.606    2.448     0.5

5      0.31        0.015       0.0281     0.0562     1.606    2.448     0.5

6      0.31        0.015       0.0281     0.0562     1.606    2.448     0.5

end_table

Input             OptRho        Calculate or Input

* If RhoOpt = Input

table horizon     Rho             (kg.m-3)	[100|2000]

1    1500.0

2    1600.0

3    1560.0

4    1620.0

5    1600.0

6    1600.0

end_table

* End If

* Maximum ponding depth and boundary air layer thickness (both location properties)

0.002             ZPndMax         (m)   Maximum ponding depth [0|1]

* Soil evaporation parameters

Boesten           OptSolEvp                   Option to select evaporation reduction method

1.0               FacEvpSol       (-)         "Crop factor" for bare soil [0.5|1.5]

0.79              CofRedEvp       (cm1/2)     Parameter in Boesten equation [0|1]

0.01              PrcMinEvp       (m.d-1)     Minimum rainfall to reset reduction

* Dispersion length of solute in liquid phase [0.5Delz|1]

Table horizon LenDisLiq (m)

1  0.05

2  0.05

3  0.05

4  0.05

5  0.05

6  0.05

end_table

* Parameter values of the functions describing the relative diffusion coefficients

MillingtonQuirk   OptCofDifRel                MillingtonQuirk, Troeh or Currie MillingtonQuirk

* If MillingtonQuirk:

2.0               ExpDifLiqMilNom (-)         Exponent in nominator of equation [0.1|5]

0.67              ExpDifLiqMilDen (-)         Exponent in denominator of eqn    [0.1|2]

2.0               ExpDifGasMilNom (-)         Exponent in nominator of equation [0.1|5]

0.67              ExpDifGasMilDen (-)         Exponent in denominator of eqn    [0.1|2]

* If Troeh:

0.5               CofDifLiqTro    (-)         Coefficient in Troeh equation     [0|1]

1.5               ExpDifLiqTro    (-)         Exponent in Troeh equation        [1|2]

0.5               CofDifGasTro    (-)         Coefficient in Troeh equation     [0|1]

1.5               ExpDifGasTro    (-)         Exponent in Troeh equation        [1|2]

* If Currie:

2.5               CofDifLiqCur    (-)         Coefficient in Currie equation    [0|-]

3.0               ExpDifLiqCur    (-)         Exponent in Currie equation       [1|-]

2.5               CofDifGasCur    (-)         Coefficient in Currie equation    [0|-]

3.0               ExpDifGasCur    (-)         Exponent in Currie equation       [1|-]

* End If

Constant          OptPnd                  Option for ponding of water

*----------------------------------------------------------------------------------------

* Section 3: Weather and irrigation data

* Description

*----------------------------------------------------------------------------------------

HAMB-M            MeteoStation     Maximum 7 (!!) characters.

Input             OptEvp           Evapotranspiration: Input, Penman or Makkink

* Initial lower boundary soil temperature [-20|40]

* Upper boundary temperature is read from meteo file

5.3               TemLboSta       (C)

* Irrigation section

No                OptIrr

* Options for OptIrr are:

* No: no irrigation

* Surface: Surface irrigation, irrigation depth spec. by user

* Surface_Auto: Surface irrigation, irrigation depth calc. by model

* Sprinkler: Sprinkler irrigation, irrigation depth spec. by user

* Sprinkler_Auto: Sprinkler irrigation, irrigation depth calc. by model

* Sprinkler_Weekly: Sprinkler irrigation, irrigation depth calc. by user

No                IrrigationData        Name of file with irrigation data

* Irrigation data have to be provided in a file Station.irr (e.g. debilt.irr);

* Maximum number of characters in filename is 7.* If RepeatHydrology is set to Yes, the first year is required only* Format of the file should be as below:* table IrrTab (mm)* 01-Aug-1980 10.0* end_table

No                IrrigationScheme   Irrigation scheme

1.0               FacPrc (-)         Correction factor for precipitation

0.0               DifTem (C)         Correction for temperature

1.0               FacEvp (-)         Correction factor for evapotranspiration

Daily             OptMetInp

Laminar           OptTraRes

No                OptRainfallEvents

No                OptSnow

*----------------------------------------------------------------------------------------

* Section 4:  Boundary and initial conditions of hydrological model

* Section 4a: Lower boundary flux conditions

* Description

*----------------------------------------------------------------------------------------

* Initial condition

-200              ZGrwLevSta (cm)   Initial groundwater level [-5000|0]

* Choose one of the following options:

* GrwLev Flux Head FncGrwLev Dirichlet ZeroFlux FreeDrain Lysimeter

FncGrwLev         OptLbo          Lower boundary option

* OptLbo = GrwLev (groundwater level boundary condition)

* Read from LowerBoundaryFile (RunId.bot)

[RunId]             LowerBoundaryFile

* table   GrwLev    (cm)                     Groundwater level [-|0]

* 01-Jan-1901  -100.0

* 31-Dec-1926  -100.0

* end_table

* OptLbo = Flux (flux lower boundary condition)

-0.250            FlvLiqLboAvg    (m.a-1)     Average annual lower boundary flux [-1|1]

0.10              FlvLiqLboAmp    (m)         Amplitude of lower-boundary flux [0|0.5]

01-Oct            DayFlvLiqLboMax             Day of maximum flux [01-Jan|31-Dec]

* OptLbo = Head (head lower boundary condition)

Elliptic          OptShapeGrwLev              Elliptic, Parabolic, Sinusoidal, NoDrains

-1.1              HeaDraBase      (m)         Drainage base to correct GrwLev [-100|0]

500.0             RstAqt          (d)         Resistance of aquitard [0|1e4]

-1.4              HeaAqfAvg       (m)         Mean hydraulic head of aquifer [-10|10]

0.2               HeaAqfAmp       (m)         Amplitude of aquifer hydraulic head [0|10]

01-Apr            TimHeaAqfMax    (d)         Day with maximum head [01-Jan|31-Dec]

* OptLbo = FncGrwLev (flux boundary condition - flux is a function of groundwater level)

-0.01             CofFncGrwLev    (m.d-1)     Coefficient in Q(h) relationship [-1|1]

-1.4              ExpFncGrwLev    (m-1)       Exponent in Q(h) relationship [-100|100]

* OptLbo = Dirichlet (pressure head boundary condition)

table   h  (m)                                Pressure head [-1e4|1e4]

01-Jan  -1.0

31-Dec  -1.0

end_table

*-------------------------------------------------------------------------------

* Section 4b: Drainage/infiltration section

*-------------------------------------------------------------------------------

No               OptDra       No, Basic or extended drainage module

No               OptSurDra    Option to consider surface drainage

0                NumDraLev    Number of drainage levels (0|5)

* If OptDra set to 'Basic' parameters below should be specified for each drainage level:

1                 SysDra_1                    Drainage system

100.0             RstDra_1        (d)         Drainage resistance [10|1e5]

100.0             RstInf_1        (d)         Infiltration resistance

20.0              DistDra_1       (m)         Distance between drains or channels [1|1e6]

1.5               ZDra_1          (m)         Bottom of drain system [0|10]

Drain             TypDra_1                    Type of drain system: Drain or Channel

1.5               ZSurWat_1       (m)         Channel water level (if TypDra_1 = Channel;

                                              otherwise dummy values)

* If OptDra set to 'Extended' parameters below should be specified for each drainage level:

1                 SysDra_1                    Drainage system

100.0             RstDra_1        (d)         Drainage resistance [10|1e5]

100.0             RstInf_1        (d)         Infiltration resistance

20.0              DistDra_1       (m)         Distance between drains or channels [1|1e6]

1.0               WidthDra_1      (m)         Bottom width of drain system

1.5               ZDra_1          (m)         Bottom of drain system [0|10]

1.5               ZGwlInfMax_1    (m)         Depth at which infiltration is maximal

Yes               OptSurDra                   Option to consider rapid subsurface drainage

* If OptSurDra set to 'Yes' then the following parameters should be specified:

30                RstSurDraDeep   (d)         maximum resistance of rapid subsurface drainage

                                              [1e-3|1e4]]

10                RstSurDraShallow(d)         minimum resistance of rapid subsurface drainage

                                              [1e-3|1e4]]

No                OptSrfWat                   Option to consider surface water system

* If OptSrfWat set to 'Yes' then the following parameters should be specified:

1.0               SrfWatLevWinter (m)         Winter surface water level

1.0               SrfWatLevSummer (m)         Summer surface water level

0.0               SrfWatSupCap    (m.d-1)     Surface water supply capacity

*----------------------------------------------------------------------------------------

* Section 5: Compound section

* Description

*----------------------------------------------------------------------------------------

* Compounds. First compound is the parent pesticide, the others are metabolites.

pest SubstanceName

table compounds

pest

end_table

EqlDom_Input    OptDT50_pest           Option for DT50: Input or Calculate

229.7           MolMas_Pest (g.mol-1)  Molar mass [10|10000]

* Transformation table (parent-daughter relationships)

* The "end" substance is the final transformation product

* Condition: Sum of rows should be 1 (see theory document)

table FraPrtDau (mol.mol-1)

end_table

* Example for a pesticide with two daughters, named "met1" and "met2":

* Line 1: pest is transformed into met1 (25%), met2 (70%) and undefined end products (5%)

* Line 2: met1 is transformed into met2 (16%) and undefined end products (84%)

* Line 3: met2 is transformed into undefined end products only (100%)

* table FraPrtDau (mol.mol-1)

* pest    met1   met2   end

* 0.00    0.25   0.70   0.05   pest

* 0.00    0.00   0.16   0.84   met1

* 0.00    0.00   0.00   1.00   met2

* end_table

* Transformation rate parameters

OptimumConditions OptCntLiqTraRef_pest       OptimumConditions or NonOptimumConditions

75.1             DT50Ref_pest (d)	           Half-life time [1|1e6]

20.0             TemRefTra_pest (C)          Temperature at which DT50 is measured [5|30]

0.7              ExpLiqTra_pest (-)          Exponent for the effect of liquid [0|5]

1.0              CntLiqTraRef_pest (kg.kg-1) Liq. content at which DT50 is measured [0|1]

65.4             MolEntTra_pest (kJ.mol-1)   Molar activation energy [0|200]

* Factor for the effect of depth [0|1]

table horizon FacZTra (-)

hor pest

1 1.0

2 0.5

3 0.5

4 0.3

5 0.3

6 0.0

end_table

* Freundlich equilibrium sorption

pH-independent    OptCofFre_pest              pH-dependent, pH-independent, CofFre

1.0               ConLiqRef_pest  (mg.L-1)    Reference conc. in liquid phase [0.1|-]

0.9               ExpFre_pest     (-)         Freundlich sorption exponent [0.1|1.3]

* If pH-independent (use the coefficient for sorption on organic matter):

70.00             KomEql_pest     (L.kg-1)    Coef. eql. sorption on org. matter [0|1e9]

70.0               KomEqlMax_pest (L.kg-1)    Coef. eql. sorption on org. matter in dry soil

* If pH-dependent (use pKa value and coefficient for sorption on organic matter):

374.7             KomEqlAcid_pest (L.kg-1)    Coef. for eql. sorption on om - acid [0|1e9]

7.46              KomEqlBase_pest (L.kg-1)    Coef. for eql. sorption on om - base [0|1e9]

4.6               pKa_pest        (-)         Coef. for influence of pH on sorption [0|14]

0.0               pHCorrection    (-)         pH correction [-2|1]

* If CofFre (specify the depth dependence and the coefficient for equilibrium sorption):

1.0               KSorEql_pest    (L.kg-1)    Coef. for equilibrium sorption [0|1e9]

0.0               MolEntSor_pest  (kJ.mol-1)

20.0              TemRefSor_pest  (C)

table horizon FacZSor (-)   Factor for the effect of depth [0|1]

hor pest

1 -99

2 -99

3 -99

4 -99

5 -99

6 -99

end_table

* End If

* Gas/liquid partitioning

0.0001           PreVapRef_pest (Pa)          Saturated vapour pressure [0|2e5]

20.0             TemRefVap_pest (C)           .. measured at [0|40]

6.6              SlbWatRef_pest (mg.L-1)      Solubility in water [1e-9|1e6]

20.0             TemRefSlb_pest (C)           .. measured at [0|40]

27.0             MolEntSlb_pest (kJ.mol-1)    Molar enthalpy of dissolution [-200|200]

95.0             MolEntVap_pest (kJ.mol-1)    Molar enthalpy of vaporization  [-200|200]

* Non-equilibrium sorption

0.0              CofDesRat_pest (d-1)   Desorption rate coefficient [0|0.5]

0.0              FacSorNeqEql_pest (-)  CofFreNeq/CofFreEql [0|-]

* Uptake

0.5              FacUpt_pest (-)   Coefficient for uptake by plant [0|10]

* Canopy processes

0.01             ThiAirBouLay (m)      Boundary air layer thickness [1e-6|1]

Lumped           OptDspCrp_pest        Lumped or Specified

* If Lumped:1000000.0        DT50DspCrp_pest (d)   Half-life at crop surface [1|1e6]

* If Specified:

1000000.0        DT50PenCrp_pest (d)    Half-life due to penetration [1|1e6]

1000000.0        DT50VolCrp_pest (d)    Half-life due to volatilization [1|1e6]

1000000.0        DT50TraCrp_pest (d)    Half-life due to transformation [1|1e6]

* End If

0.0001           FacWasCrp_pest (m-1)    Wash-off factor [1e-6|0.1]

* Diffusion of solute in liquid and gas phases

20.0             TemRefDif_pest (C)            Diff. coeff measured at temperature [10|30]

4.3E-5           CofDifWatRef_pest (m2.d-1)    Reference diff. coeff. in water [10e-5|3e-4]

0.43             CofDifAirRef_pest (m2.d-1)    Reference diff. coeff. in air [0.1|3]

*----------------------------------------------------------------------------------------

* Section 6: Management section and initial and boundary conditions of pesticide fate model

* Description

*----------------------------------------------------------------------------------------

FOCUS_EXAMPLE ApplicationScheme

1.0               ZTgt (m)        Depth of Focus target layer [0.1|Z(N)-1]

1                 DelTimEvt (a)   Repeat interval of events [NoRepeat|1|2|3]

* Event table:

* Column 1: Date

* Column 2: Event type: AppSolSur, AppSolInj, AppSolTil, AppCrpUsr, AppCrpLAI

* If Event = AppSolSur (soil surface application):

* Column 3: Dosage (kg/ha) [0|-]

* If EventType = AppCrp (application to the crop canopy):

* Column 3: Dosage (kg/ha) [0|-]

* Column 4: Optional: Fraction of dosage applied to the crop canopy (-) [0|1]

* End If

table Applications

01-Emg-01 AppSolSur 1.0

end_table

* Tillage table - can be empty

table TillageDates

end_table

* Initial conditions                 Concentration in equilibrium domain [0|-]

* If using metabolites, ConSysEql should be specified for all metabolites

table interpolate CntSysEql (mg.kg-1)

z         pest

0.0       0.0

50.0      0.0

end_table

* Initial conditions                  Concentration in non-equil. domain [0|-]

* If using metabolites, ConSysNeq should be specified for all metabolites

table interpolate CntSysNeq (mg.kg-1)

z         pest

0.0      0.0

50.0     0.0

end_table

No DepositionScheme

* Upper boundary flux                         [0|-]

table    FlmDep   (kg.ha-1.d-1)

01-Jan-1980  0.0

31-Dec-1989  0.0

end_table

0.2               ZTil (m)    tillage depth

*----------------------------------------------------------------------------------------

* Section 7: Crop section

* Description

*----------------------------------------------------------------------------------------

HAMB-WCEREALS CropCalendar

Yes               RepeatCrops     Repeat crop table: Yes or No

Fixed             OptLenCrp        Fixed or Variable

* Emergence and harvest date of crop.

* Note: Length of growing season must be constant for one crop

* If repeat crops: Specification of year not required

table  Crops

01-Nov           10-Aug        WCEREALS1

end_table

* Crop cycle fixed or variable (calculated from temperature sum)

Fixed    OptLenCrp                            Fixed or Variable

* If OptLenCrp = Variable:

0.0            TemSumSta_WCEREALS1     (C)    Start value of temperature sum [-10|20]

0.0            TemSumEmgAnt_WCEREALS1  (C)    Sum from emergence to anthesis [0|1e4]

0.0            TemSumAntMat_WCEREALS1  (C)    Sum from anthesis to maturity  [0|1e4]

* End If

* Crop parameters as a function of development stage

* Column 1: Development stage: 0 = emergence; 1 = harvest (-)       [0|1]

* Column 2: LAI: Leaf Area Index                      (m2.m-2)      [0|12]

* Column 3: FacCrp: Crop factor                       (-)           [0|2]

* Column 4: ZRoot: Rooting depth                      (m)           [0|10]

* Column 5: HeightCrp:  Crop height                   (m)           [0|10]

*  LAI   FacCrp  ZRoot  HeightCrp

table  CrpPar_WCEREALS1

0.0    0.0    1.05   0.0    0.0

0.65   0.1    1.05   0.2    0.0

0.751  3.8    1.05   1.0    0.0

0.754  3.8    1.1    1.0    0.0

0.911  3.8    1.1    1.0    0.0

0.915  3.8    0.7    1.0    0.0

1.0    3.8    0.7    1.0    0.0

end_table

* Root density table (first column is relative depth)

* Column 1: Relative depth 0 = soil surface; 1 = DepRoot  (-)           [0|1]

* Column 2: Root density distribution                                (-)           [0|1]

table  RootDensity_WCEREALS1

0.0    1.0

1.0    1.0

end_table

* Crop water use

0.0             HLim1_WCEREALS1 (cm)              Anaerobiosis point  [-100|0]

-1.0            HLim2_WCEREALS1 (cm)              Wet reduction point [-1000|0]

-500.0          HLim3U_WCEREALS1 (cm)             Dry reduction point [-10000|0]

-900.0          HLim3L_WCEREALS1 (cm)             Dry reduction point [-10000|0]

-16000.0        HLim4_WCEREALS1 (cm)              Wilting point       [-16000|0]

70.0            RstEvpCrp_WCEREALS1 (s.m-1)       Min. canopy resistance [0|1000]

0.39            CofExtDif_WCEREALS1 (-)

1.0             CofExtDir_WCEREALS1 (-)

0.0001          CofIntCrp_WCEREALS1 (cm)          Constant in Braden eq for interception [0|1]

0.2             ZTensiometer_WCEREALS1 (m)

-100.0          PreHeaIrrSta_WCEREALS1 (cm)

15.0            IrgThreshold_WCEREALS1 (mm)

*----------------------------------------------------------------------------------------

* Section 8: Output control

* Description

*----------------------------------------------------------------------------------------

* First, specify the time format in the output file:

* DaysFromSta  : Print number of days since start of simulation

* DaysFrom1900 : Print number of days since 1900* Years : Print years table VerticalProfiles

end_table

No           OptDelOutFiles

Yes          LeachingReport

DaysFromSta      DateFormat                   Format of time column in output file

* Format of the ordinary output - use FORTRAN notation:

* e is scientific notation, g = general is general notation

* Then follow the number of positions

* Then the number of digits

G12.4            RealFormat                   Format of ordinary output

* Second, specify the nodal heights for which output is requestedtable OutputDepths (m)

0.05

0.1

0.2

0.3

0.4

0.5

0.75

1.0

2.0

end_table

* Finally, specify for all variables whether output is wanted (Yes or No)

* As Pearl can potentially generate large output files, it is recommended to minimise

* the number of output variables

* Section I : Output from the SWAP model, version 3.2.30

* General variables

Yes               print_GrwLev           Groundwater level (m)

No                print_LAI              Leaf Area Index (m2.m-2)

No                print_ZRoot            Rooting depth (m)

Yes               print_FacCrpEvp        Crop factor (-)

No                print_FraCovCrp        Soil cover (-)

No                print_AvoLiqErr        Water balance error (m)

No                print_StoCap           Phreatic storage capacity (m3.m-2)

No                print_AvoLiqSol        Amount of water in soil

No                print_ZPnd             Ponding depth (m)

No               print_RstAirLam         Resistance to transport through laminar air layer (s.m-1)

* State variables

Yes               print_Tem              Soil temperature (C)

Yes               print_Eps              Volumic air content (m3.m-3)

Yes               print_Theta            Volumic soil water content (m3.m-3)

No                print_PreHea           Soil water pressure head (m)

* Volumic volume rates (m3.m-3.d-1)

No                print_VvrLiqDra        Volumic volume rate of drainage

No                print_VvrLiqUpt        Volume flux of water uptake

* Volume fluxes (m3.m-2.d-1)

No                print_FlvLiq           Volume flux of vertical soil water flow

Yes               print_ FlvLiqPrc       Volume flux of precipitation

Yes               print_FlvLiqIrr        Volume flux of water in irrigation

No                print_FlvLiqInf        Volume flux of liquid infiltrating into the soil (m3.m-2.d-1)

Yes               print_FlvLiqLbo        Volume flux of water leaching from the soil system

Yes               print_FlvLiqEvpIntPrc  Evaporation flux of intercepted rainfall

Yes               print_FlvLiqEvpIntIrr  Evaporation flux of intercepted irrigation

Yes               print_FlvLiqEvpSol     Volume flux of evaporation from the soil surface

Yes               print_FlvLiqEvpSolPot  Idem, potential

Yes               print_FlvLiqTrp        Volume flux of transpiration by plant roots

Yes               print_FlvLiqTrpPot     Idem, potential

No                print_FlvLiqDra_1      Volume flux of drainage to level 1

No                print_FlvLiqDra_2      Volume flux of drainage to level 2

No                print_FlvLiqDra_3      Volume flux of drainage to level 3

No                print_FlvLiqDra_4      Volume flux of drainage to level 4

No                print_FlvLiqDra_5      Volume flux of drainage to level 5

No                print_FlvLiqGrw        Volume flux groundwater recharge

No                print_FlvLiqGrwSur     Groundwater flux (m.d-1)

* Section II : Output from the PEARL model

* Remark: All fluxes are averages over the print interval

*--------------------------------------------------------

* Time step

No                print_DelTimPrl        Average time-step during the print interval (d)

* Mass balance (kg.m-2)

Yes               print_AmaEqlPro        Areic mass in equilibrium domain of profile

No                print_AmaEqlTil        Areic mass in equilibrium domain of tillage layer

Yes               print_AmaEqlTgt        Areic mass in equilibrium domain of the target layer

Yes               print_AmaNeqPro        Areic mass in non-eql. domain of profile

No                print_AmaNeqTil        Areic mass in non-eql. domain of tillage layer

Yes               print_AmaNeqTgt        Areic mass in non-eql. domain of the target layer

Yes               print_AmaSysPro        Areic mass of pesticide in the system

No                print_AmaSysTil        Areic mass of pesticide in the tillage layer

Yes               print_AmaSysTgt        Areic mass of pesticide in the target layer

Yes               print_AmaAppSol        Areic mass applied to the soil system

Yes               print_AmaDraPro        Areic mass of lateral discharge

Yes               print_AmaForPro        Areic mass of formation

Yes               print_AmaTraPro        Areic mass of pesticide transformation

Yes               print_AmaUptPro        Areic mass of pesticide uptake

No                print_AmaDra_1         Areic mass of drainage to level 1

No                print_AmaDra_2         Areic mass of drainage to level 2

No                print_AmaDra_3         Areic mass of drainage to level 3

No                print_AmaDra_4         Areic mass of drainage to level 4

No                print_AmaDra_5         Areic mass of drainage to level 5

Yes               print_AmaErrMic        Areic numerical mass error

 * Pesticide concentrations (kg.m-3) and contents (kg.kg-1)

Yes               print_ConLiq           Concentration in liquid phase

No                print_ConGas           Concentration in gas phase

No                print_ConSysEql        Concentration in equilibrium domain

No                print_ConSysNeq        Concentration in non-equilibrium domain

Yes               print_ConSys           Concentration in the soil system

No                print_CntSorEql        Mass content at soil solid phase

Yes               print_ConLiqSatAvg     Avg. conc.in liq. phase between 1-2 m

Yes               print_ConLiqLbo        Concentration in percolate

No                print_ConLiqDra        Concentration in drainage water

No                print_ConLiqDra_1      Concentration in drainage water, system 1

No                print_ConLiqDra_2      Concentration in drainage water, system 2

No                print_ConLiqDra_3      Concentration in drainage water, system 3

No                print_ConLiqDra_4      Concentration in drainage water, system 4

No                print_ConLiqDra_5      Concentration in drainage water, system 5

* Pesticide mass fluxes (kg.m-2.d-1)

No                print_FlmLiq           Pesticide mass flux in liquid phase

No                print_FlmGas           Pesticide mass flux in gas phase

No                print_FlmSys           Total pesticide mass flux (FlmLig+FlmGas)

Yes               print_FlmLiqLbo        Accumulated mass flux at the lower boundary

Yes               print_FlmLiqInfSys     Accumulated mass flux of pesticide infiltration

Yes               print_FlmGasVol        Accumulated mass flux of pesticide volatilisation

* Canopy interaction*-------------------

No                print_AmaCrp           Areic mass of pesticide at the canopy

No                print_AmaAppCrp        Areic mass of pesticide applied to the canopy

No                print_AmaDspCrp        Areic mass rate of pesticide dissipation

No                print_AmaHarCrp        Areic mass rate of pesticide removal by harvest

No                print_AmaWasCrp        Areic mass rate of pesticide wash-off

No                print_FlmDepCrp        Areic mass rate of pesticide deposited on canopy

*-------------------------------------------------------------------------------

* End of FOCUSPEARL input file

*-------------------------------------------------------------------------------

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Print button

Use the print button to print a topic.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Contents button

Use the Contents button to get a table of contents.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Index button

Use the Index to find out where you have to specify a certain parameter.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Back button

Use the Back button to go to the previous displayed topic. Use the History window to jump to an earlier displayed topic (the History window can be displayed using Options - Display History).

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Browse buttons

Use the Browse buttons of the help system (<< and >>) to browse through the help-file as if it where a printed book. These buttons are very efficient if you first jump to a topic and then start browsing (you can for example read the Theory section).

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Get Start button

Use the Get Started button to go to the Get Started topic

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Cover page button

Use the Cover page button to jump to the Cover page

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Support button

Use the Support button to get information about support, e-mail addresses, etc.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Tree view button

Use the Tree view button to display a tree of the PEARL user interface.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Theory button

Use the Theory button to enter the Theory section of the Help file. You can use the browse buttons to actually read this section.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Introduction

Read this part to obtain some background information and to find out how the PEARL User Interface works.

About PEARL

Model uses

Overview of the system

Overview of the PEARL database

Overview of screen functions

The FOCUS wizard

References

Support

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Tree view of GUI

Use this diagram to get an overview of the PEARL User Interface. Click on the diagram to jump to topics related to specific forms of the User Interface.

Overview of the PEARL User Interface

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Getting Started

Read this part to learn most of what you need to run the model. This part will get you started with first-tier assessments (FOCUS) as quickly as possible. Don't worry if you do not understand everything at this stage -- you will learn more if you use the model more intensively.

First-tier of the European registration procedure: Generating FOCUS runs

The FOCUS wizard

Using PEARL for higher-tier assessments

Using the command line version of PEARL

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Main form

This page gives a graphical representation of the main form of the PEARL User Interface. Find out how the most important form of the User Interface works.

The main form

The FOCUS wizard

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The model

This page will guide you through the process descriptions.

Overview of processes

References

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Support

Although we are not commercial suppliers, we do our best to offer support. Follow the links.

Support and downloading

Manuals

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


RIVM

The National Institute of Public Health and Environmental Protection

PO BOX 1

3720 BA Bilthoven

The Netherlands

Please visit our website

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Alterra

Alterra

PO BOX 47

6700 AA Wageningen

The Netherlands

Please visit our website

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Netherlands Environmental Assessment Agency

MNP

PO BOX 303

3720 AH Bilthoven

The Netherlands

Please visit our website

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Manuals

•	Tiktak, A. F. van den Berg, J.J.T.I. Boesten, M. Leistra, A.M.A. van der Linden and D. van Kraalingen. 2000. User manual of FOCUS PEARL 1.1.1. RIVM report no. 711401008. RIVM, Bilthoven, the Netherlands.

•	Leistra, M., A.M.A. van der Linden, J.J.T.I. Boesten, A. Tiktak and F. van den Berg. 2000. PEARL model for pesticide behaviour and emissions in soil-plant systems. Description of processes. Alterra report 013, Alterra, Wageningen, the Netherlands.

Both reports are available as a hard-copy or in pdf format distributed with the PEARL software.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


PESTLA

In the Netherlands, PESTLA 1.1 (Pesticide Leaching and Accumulation; Van der Linden and Boesten, 1989) has been used on a regular basis for assessing the accumulation and leaching of pesticides in soil. As early as 1976, precursors of the pestla model were operational as tools for Dutch legislation purposes (Leistra and Dekkers, 1976). Versions 1.x of the PESTLA model were written in CSMP. The most important limitation of this model version was its inflexibility: Pesticide properties, hydrological conditions and weather data were introduced into the source code. This inflexibility stimulated the development of new models and model versions. The pestla model was further developed by Van den Berg and Boesten (1998). This model was loosely coupled with the hydrological model SWAP (Soil Water Atmosphere Plant model), which also provided the heat flow algorithm (Van Dam et al., 1999). Processes like adsorption-desorption kinetics, the formation and behaviour of reaction products, and vapour diffusion in the gas phase were included.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


PESTRAS

In the mid-nineties, the PESTRAS (Pesticide Transport Assessment) model was developed by Tiktak et al. (1994) and Freijer et al. (1996). PESTRAS was developed primarily for regional-scale applications (Tiktak et al., 1996ab). The description of pesticide behaviour in soil was similar to that in PESTLA. However, PESTRAS was coupled to a different model for soil water flow (i.e. the SWIF model developed by Tiktak et al., 1992) and heat transport. The description of vapour transport (both convective and diffusive) was taken from Freijer (1994). Concepts were developed on the volatilisation of pesticide from a film residing at the soil surface. The model further included a comprehensive description of the formation of reaction products.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Browse box

The browse box allows you to scroll through the records of a table in the PEARL database. From the browse box, you can

•	Select a record by scrolling

•	Add a record with the + key of the navigator

•	Delete a record with the - key of the navigator

You cannot edit the contents of the records - this has to be done in the edit box

You will notice that the information in the edit box changes when scrolling.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Edit box

In the edit box of a form you can edit the record that you have selected in the browse box. The PEARL user interface has three categories of data fields:

·	Data fields.

·	Combo-boxes

·	Check boxes

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Button

Some forms contain buttons to enter underlying forms. More commonly, however, you will use browse buttons to go to an underlying form.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Navigator

The series of buttons that allows you to perform actions in the browse box of a form.

See also Copy button

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


First record button

Go to the first record in the table

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Last record button

Go to the last record in the table

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Add button

Add a new record

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Delete button

Delete a record

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Confirm button

Confirm changes ('post edit'). Use this button to save the changes you have made. Changes will also be saved if you use the leave the form.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Discard button

Use this button to discard the changes and leave the database unaffected.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Browse button

The button to the right of a combo-box (the browse button) allows you to edit or view the underlying tables (i.e. go to a lower hierarchical level in the database).

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Scroll bar

Use the scroll bar to select one of the topics in the browse box.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The Status bar

The Status bar to the left-hand side of the browse box shows if a record has been changed. If the cursor looks like a triangle, the record has not been changed. If the cursor looks like a star, it has been altered and must be saved before leaving the form.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Copy button

Use the copy button to copy an existing record. PEARL will also copy the field in the linked tables.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Active tab

Some forms consist of tabs. Just click on a tab to make it active.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Inactive tab

Some forms consist of tabs. Just click on a tab to make it active.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Combo-box

Here, you can make a choice between a number of options or records in a database table. The button to the right of a combo-box (the browse button) allows you to edit or view the underlying tables (i.e. go to a lower hierarchical level in the database).

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Check box

In a check box, you can switch an option on or off.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Comments button

After pressing the comments button, you will enter an editor were you can type text. This text is stored together with the data, and can be used for archiving.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Data-field

In a data-field, you can enter a text string, a date string, or numerical data. The PEARL user interface will perform range checking when you go to a different form or if you press [image] on the navigator. If a variable is out-of-range you will get an error message.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Required data-field

If you create a new record with the + button in the navigator, some data-fields will be empty. These fields must always be filled-in.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Data-field with default values

If you create a new record, you will see that some field are already filled-in by the system. These are default values, which can be overruled or accepted. In many cases, the default value is reasonable.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Disabled or locked

If a button or data-field is grey, it cannot be used because:

•	The user has selected an option that makes a data-field or button irrelevant

•	The data is part of a fixed scenario, which may not be changed (locked datafields).

•	Another action must be performed before the button can be used (e.g. in the main form, you must run the model before you can look at the output).

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Close button

By pressing this button, you will leave the form. If you have changed data, the system will ask for a confirmation. The system will perform range checking. If a variable is out-of-range you will get a general SQL error.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Help button

Pressing the Help button will start context sensitive help. You can also press the F1 button.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Step 1. Create or edit a substance
Create or edit a substance

To Create a new substance do the following:

•	Click the browse button to the right of the substance combo-box in the scenario tab of the main form to go to the Substance form.

•	Click + in the navigator.

•	Fill-in at least the following substance properties:

-	In the General tab, specify a unique code, a name, the molar mass, the saturated vapour pressure and the solubility in water.

-	In the Freundlich tab, specify the coefficient for sorption on organic matter.

-	In the Transformation tab, specify the substance half-life.

Refer to the links for ranges and further guidance.

•	Click Close when done to return to the main form.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Step 2. Create or edit one or more application scheme(s)
Create or edit one or more application scheme(s)

To Create a new application scheme do the following:

•	Click the browse button to the right of the application schemes combo-box in the scenario tab to go to the Applications form

•	Click + on the navigator in the application schemes box (left-hand side of form) to create a new application scheme or use the Copy button to copy an existing scheme.

•	Fill-in a code and a name.

•	Use the tabs in the right hand side of the form to select between absolute and relative application dates. Absolute and relative applications can be mixed in one application scheme.

•	Click + on the navigator of the applications box (right-hand side of form) to add an application  or use the Copy button to copy an existing application.

•	In the case of an absolute application, fill-in the application date, the dosage and application type.

•	In the case of a relative application, specify the following information:

-	Select between harvest or emergence

-	Select the application type

-	Enter the number of days before or after crop emergence or crop harvest. Negative numbers denote before, positive numbers denote after.

-	Enter the dosage.

•	Click Close when done to return to the main form

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Relative application dates

In many cases, a pesticide dossier lists the application date relative to crop emergence or crop harvest, e.g. the substance must be applied 3 days before emergence. PEARL can handle these relative application dates. Use the 'Relative applications' tab to enter applications relative to crop emergence or crop harvest.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Absolute application dates

Absolute application dates are defined by a date, and are not dependent on crop emergence or crop harvest. Use the 'Absolute applications' tab to enter absolute application dates.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Step 3. Run the FOCUS wizard
Run the FOCUS wizard

Press the FOCUS wizard button to generate one or more standard runs

•	Select one or more crop types and press Next

•	Select one or more locations and press Next

•	Select a substance, an application scheme and a long-term application scheme (repeat interval of application, which can be 1, 2 or 3 years).

•	Select the project where you want to store the new run(s). You can add the new run(s) to an existing project or create a new project.

•	Note that you can only select one application scheme and one substance for all runs. This can be refined in the next step.

•	Press Finish to go back to the main form

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Step 4. Refinement
Refinement

PEARL has now generated a FOCUS project or has added the new run(s) to an existing project. You will see that all new runs in the project have been selected for execution.

•	You can now choose different application schemes for each individual run. Use the application schemes combo-box for this purpose.

•	Notice that you can use days relative to crop emergence. By using relative application dates, it is often not necessary to creating different application schemes.

•	If you want to create user-defined graphs, check 'Detailed Output' in the Output Control tab.

•	You can switch runs on and off by double clicking.

•	You can make copies of existing runs, if you want to edit other model parameters. Notice, however, that so created model runs are not FOCUS runs!!

•	If there are indications that the depth dependence of transformation is different, you may edit the depth dependence of transofrmation. The depth dependence of transformation can be entered in the Soil profile form. You must make a copy of a FOCUS run, before you can edit the depth dependence of sorption.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Step 5. Running PEARL
Running PEARL

Press the Calculate button to actually run the model.

•	All selected runs will be carried out.

•	If Multiple Runs were selected, a dialog will appear:

•	Stop execution when an error occurs

•	Start model calculations in minimized mode

•	The PEARL User Interface will write the input files and call the simulation kernel.

•	You can follow the course of the simulation.

When all runs are completed, you will see the status bar changing to 'Results there'

•	If errors are encountered, you will see that the Reports and Graphs buttons are disabled.

•	Errors can be reviewed in the Run Status tab of the main form.

You can select all runs for execution or deselect all runs for execution through the runs menu of the main form.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Step 6. Viewing the Results
Viewing the Results

•	Press the Reports button to view the summary report. This report contains, amongst others:

−	the water and substance balances.

−	the 80th percentile of the leaching concentration.

•	Press the Graphs, predefined button to view graphs of

−	The water and substance balances

−	The FOCUS summary

•	User defined graphs can only be created if you have checked the 'detailed output' checkbox in the output control tab.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Project Dutch Standard scenario
Project Old Dutch Standard scenario

To create a new run, you have to go to the project where the example runs are stored.

•	Press the Project button of the main form.

•	Select project 'Old Dutch standard scenario, for demonstration'.

•	Press OK to enter the project.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Copy the example run

•	Select one of the two example runs:

−	Old Dutch standard scenario, spring application considers one application of 1 kg/ha of pesticide on May, 25.

−	Old Dutch standard scenario, autumn application considers one application of 1 kg/ha of pesticide on November 1.

•	You will see that the example runs cannot be edited (all boxes are gray)

•	Use the Copy button to make a copy of one of these runs. You will notice that this copy can be edited.

•	Enter a new name in the Name field.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Edit the copied run

•	Use the combo boxes to select:

-	A Substance

-	An Application scheme, if different from the default application schemes.

•	The old Dutch standard scenario uses standard parameters for most soil, crop and weather variables (see the user manual), so do not edit the other parameters.

•	If there are indications that the depth dependence of transformation is different, you may edit this depth dependence. The depth dependence of transformation can be entered in the Soil profile form.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Viewing the Results

•	Press the Reports button to view the summary report. This report contains, amongst others:

-	The maximum average substance concentration in the upper groundwater

-	The fraction of the dosage leached into the groundwater

-	The areic mass of substance in the plough layer at 365 days after application (a measurement of persistence)

•	Press the Graphs, predefined button to view graphs of the water and substance balances

•	User defined graphs can only be created if you have checked the 'detailed output' checkbox in the output control tab. A graph of the concentration in the upper groundwater can be created by selecting 'Average substance concentration in the liquid phase of the upper groundwater'.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Create the building blocks of your model runs(s)

Before you can create model run(s), you have to create the building blocks of your run. Go the scenario tab of the main form and create:

One or more locations

One or more crop calendars

One or more substances

One or more application schemes

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Create a location

To add a location, do the following:

•	Go the Locations form

•	Before doing anything in the Locations form, add the building blocks of a location:

-	Go to the Soil Profiles form and build a soil profile. To see how, click here.

-	Go to the Meteo Stations form to create a new meteo station. You can import a weather data file into the database.

•	Add a new location with the navigator

•	Fill in the Locations form

-	Don't forget to define the lower boundary conditions of the hydrological model. PEARL has a special lysimeter boundary conditions.

-	You can optionally specify a local drainage system. You must select the 'Calculate lateral drainage' checkbox before entering the Drainage levels form.

•	Save the new Location using the Confirm button of the navigator.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Create a crop calendar
Create crop calendar(s)

To add a Crop Calendar, go to the Crop calendar form.

Building a crop calendar

Agricultural years

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Create a project

Once you have your Building Blocks available, click the Projects button at the main form and create a new project.

Creating projects

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Create model runs(s)

You can now fill your new project with model runs. Go to the scenario tab of the main form, then:

•	Add a new run with the navigator

•	Give the run an appropriate name

•	Use the combo boxes to select at least the following four building blocks:

-	Select a location

-	Select a Crop calendar

-	Select a Substance

-	Select an Application scheme

•	Go to the Simulation control tab and enter the time-domain, i.e.

-	Start date

-	End date

•	Press Confirm on the navigator to save your run.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Run the model

You can select runs for execution by double clicking in the Browse box of the main form. Then, press the Calculate button to actually run the model.

•	All selected runs will be carried out.

•	The PEARL User Interface will write the input files and call the simulation kernel.

•	You can follow the course of the simulation.

When all runs are completed, you will see the status bar changing to 'Results there'

•	If errors are encountered, you will see that the Reports and Graphs buttons are disabled.

•	Errors can be reviewed in the Run Status tab of the main form.

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Review the resuls
Review the results

In the case of higher-tier assessments, you will often have to look at specific model outputs, so the predefined graphs will usually not be sufficient. Refer to the following pages:

User defined graphs.

Exporting data.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The browse runs box

The columns represent:

•	The run ID, which is generated automatically.

•	A column, which indicates whether a run is selected for execution.

•	The name of the run.

•	ResultsSummary: Indicates whether a summary file is available

•	ResultsDetailed: Indicates whether a file with daily model outputs is available

You can select a run for execution by double clicking.

You must press the Calculate button to actually execute the selected runs.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The edit runs box

In this box, you can actually edit the selected run. The edit box contains four tabs.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The tabs in the edit runs box

The Scenario tab where you can specify the model input (excluding all simulation control parameters!).

The Simulation control tab where you can control the simulation (e.g. set the start- and end time of the simulation).

The Output control tab where you can control the model output.

The Run status tab, which allows you to view status of a run.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The main menu

A shortcut menu, from where you can directly jump to underlying screens:

•	Use File-Exit (Alt-F-X) to quit the application or to open another database.

•	Use the Edit menu (Alt-E) to directly access a table in the database. As an example, use Edit-Substances or Alt-E-S to jump to the substances form.

•	Use the View menu (Alt-V) to view the PEARL input, log and output files. To see a listing with explanation, click here.

•	Use the Calculate menu (Alt-C) to execute selected runs.

•	Use the Graphs menu (Alt-G) to create graphs and graph templates.

•	Use the Runs menu (Alt-R) to

-	select and deselect runs for execution

-	archive runs

-	move runs to another project

•	Use the Help menu (Alt-H) to access the help file.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The scenario box

Scenario's are defined by the FOCUS modelling working group (2000) and are a unique combination of crop type, location, the long-term application schedule (i.e. annual, biennial or triennial applications) and agronomic parameters (particularly irrigation data) to be used in the simulation. Locations in its turn are a combination of soil profiles, weather stations and parameters describing the regional and local groundwater system.

A scenario in PEARL and FOCUS context is merely a unique combination of general environmental conditions.

Tree view of User Interface

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Pesticide box

In this box, you will find the application scheme, the substance and the deposition scheme. You must further specify the initial conditions for the parent pesticide.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The projects button
The main button bar

•	The Projects button gives access to the projects form.

•	The Calculate button must be used to execute all selected model runs.

•	The Focus Wizard button gives access to the FOCUS wizard.

•	The Help wizard gives access to the Contents and Index pages of the Help file

•	Use Exit button to Close the System

See also Getting Started to learn about generating FOCUS runs.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Graphs and Reports buttons

These buttons give access to the model output (the buttons can only be used if a run has been completed successfully):

•	The 'Reports' button, which gives access to model outputs used in the pesticide registration procedure.

•	The 'Graphs, user defined' button, which gives access to daily model output.

•	The 'Graphs, predefined' button, which gives access to summary graphs (particularly annual water- and mass balances).

These buttons are disabled if the model has not yet been run. The 'Graphs, user defined' button is disabled if the 'detailed output' switch in the output control tab has been switched off.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Scenario

Scenario's are defined by the FOCUS modelling working group (2000) and are a unique combination of crop type, location, the long-term application schedule (i.e. annual, biennial or triennial applications) and agronomic parameters (particularly irrigation data) to be used in the simulation. Locations in its turn are a combination of soil profiles, weather stations and parameters describing the regional and local groundwater system.

A scenario in PEARL and FOCUS context is merely a unique combination of general environmental conditions.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Initial conditions

The user must specify the initial mass content of substance (mg/kg) as a function of depth (m). The model will interpolate between the depths given in the table. Initial conditions must be specified for both the equilibrium and the non-equilibrium domains.

The model will usually start with pesticide-free soil, i.e. the initial mass content of pesticide is zero. Only in the case of old residue, you may want to start with non-zero values.

Theory

Back to main form

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Concentration in irrigation water

Substances can be added to irrigation water. Dependent on the type of irrigation (i.e. sprinkler or surface irrigation), substances will interact with the crop canopy. The substance concentration must be given in mg/L and must be >= zero.

Theory

Canopy processes

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Vertical discretization of the soil profile

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Contents of the weather data file

Column	Required if evaporation option is

Penman	Makkink	Input

Meteostation code.	Yes	Yes	Yes

Day, between 1 and 31	Yes	Yes	Yes

Month, between 1 and 12	Yes	Yes	Yes

Year, between 1900 and 3000	Yes	Yes	Yes

Daily global radiation (kJ m-2 d-1), between 0 and 5 E6	Yes	Yes	No

Minimum daily temperature (deg C), between -50 and 35	Yes	Yes	Yes

Maximum daily temperature (deg C), between -30 and 60	Yes	Yes	Yes

Average vapor pressure (kPa), between 0 and 10	Yes	No	No

Average windspeed (m/s), between 0 and 50	Yes	No	No

Daily precipitation (mm/d), between 0 and 1000	Yes	Yes	Yes

Reference evapotranspiration (mm/d), between 0 and 100	No	No	Yes

Example

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Example of a weather data file

The example shows part of a weather data file with the evaporation option set to 'input'.

***************************************************************************

* File name: debilt.met

* Meteo data for the old Dutch standard scenario

***************************************************************************

* Station   DD MM YYYY     RAD   Tmin   Tmax    HUM    WIND   RAIN    ETref

*           nr nr   nr  kJ.m-2      C      C    kPa   m.s-1  mm.d-1 mm .d-1

 'debilt'   1  1  1980   -99.9     .9     .9  -99.9   -99.9     5.8     0.0

 'debilt'   2  1  1980   -99.9    -.4    -.4  -99.9   -99.9     0.6     0.0

 'debilt'   3  1  1980   -99.9   -2.3   -2.3  -99.9   -99.9     1.3     0.0

...

...

 'debilt'  30 12  1989   -99.9    7.7    7.7  -99.9   -99.9     0.0     0.2

 'debilt'  31 12  1989   -99.9    7.3    7.3  -99.9   -99.9     0.0     0.2

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Time depenent groundwater level
Time dependent groundwater level

If the lower boundary condition is set to time-dependent groundwater level, the groundwater level (cm) must be specified as a function of the date-in-year. The model will interpolate between records in the table. The groundwater level must be < 0. Time-series can be input. Please read carefully the instructions before importing.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Sine function

If the lower boundary condition is set to sine function, the daily regional bottom flux is calculated using a sine function. The user must specify:

•	The mean annual bottom flux (m/a). A negative value indicates downward flow. The mean annual bottom flux must be between -1 and 1 m/a.

•	The annual amplitude of the bottom flux (m). Its value must be between 0 and 0.5 m.

•	The date at which the maximum of the sine wave occurs. Normal date notation can be used. The maximum of the sine wave usually occurs in late-summer or early autumn.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Flux from deep aquifer
Cauchy condition

If the lower boundary condition is set to flux from deep aquifer, the regional bottom flux is calculated using the head difference between the phreatic groundwater and the groundwater in the semi-confining aquifer (see figure and theory). The following parameters must be specified:

•	The drainage base (m), which is needed to calculate the average groundwater level in the field. The drainage base must be between -100 and 0 m.

•	An option for the shape of the groundwater table. The groundwater table shape option can be Elliptic, Parabolic, Sinusoidal or NoDrains (i.e. a flat groundwater table).

•	The daily value of the hydraulic head in the semi-confining aquifer is described by a sine-wave. The user must specify:

-	The mean annual hydraulic head m). Its range is -10 - 10 m.

-	The amplitude of the hydraulic head (m). Its value must be between 0 and 10 m.

•	The date at which the maximum hydraulic head occurs.

•	The vertical resistance of the aquitard (d). Its value must be between 0 and 10000.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Flux boundary condition

The bottom flux is calculated as a function of the groundwater level, using an empirical groundwater level - flux relationship. This equation has two parameters:

•	The coefficient (m/d). Its value must be between -1 and 1. A negative value indicates downward flow, a positive value indicates upward flow.

•	The exponent (1/m). It value must be between -100 and 100.

Please realise that this option is only valid for deep, sandy areas. The calculated bottom flux includes local drainage to surface waters and drains, so local drainage should be set to zero if this option is used.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Pressure head lower boundary conditions

If the lower boundary condition is set to pressure head boundary condition, the pressure head at the lower boundary (cm) must be specified as a function of the date-in-year. The model will interpolate between records in the table. Time-series can be input. Please read carefully the instructions before importing.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Pseudo two-dimensional Cauchy lower boundary condition, in case of drainage to ditches.

•	qbot is the regional bottom flux

•	qdrain is the local drainage flux to ditches and field-drains

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Free drainage, Lysimeter and Zero Flux boundary conditions

These options does not require additional input.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Development Stage

PEARL uses the concept of development stages to describe the time-dependence of crop properties. The development stage is:

•	0 at emergence (NOT seeding date!!)

•	0.5 at flowering (anthesis)

•	1 at maturity

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Application scheme

An application scheme consists of one or more applications. Each application is defined by:

•	An absolute date or a date relative to the emergence date

•	The application type (e.g. surface application)

•	The dosage

If you use the repeat applications option, only the date within the year is relevant!

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Date

If you use the repeat applications option, only the date within the year is relevant!

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Data-sources
References

•	Hornsby, G.H., R.D. Wauchope and A.E. Herner. 1996. Pesticide properties in the Environment. Springer Verlag, New York.

•	Tomlin, C. (Ed.). 1994. The Pesticide Manual. 10th Edition. Crop Protection Publications, Royal Soc. Chemistry, Cambridge, UK.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Bentazone incubation experiments

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Example of a simple incubation experiment

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Simple chain reaction scheme for the example described

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Format specifiers

FORTRAN format specifiers, contain two digits, i.e. w which represents the width and d, which represents the number of digits to be displayed. Further, there are three possible suffixes, i.e. F, E and G:

•	F<w.d>:	Fixed format. Using F14.3, printing the number 1.23 will result in: 1.230

•	E<w.d>:	Exponent format. Using E14.3, printing 1.23 will result in: 0.123E+01

•	G<w.d>:	General format. Using G14.3, printing 1.23 will result in 1.23

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Example of the effect of the print interval on the generated model output.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The FOCUS target layer

The FOCUS target layer must be specified in the Output control tab. It determines:

•	The depth at which the 80th percentile of the leaching concentration is calculated

•	The depth for which water and mass balances are calculated.

As prescribed by the FOCUS working group (1997), the default value for the FOCUS target layer is 1 m.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


FOCUS periods

All FOCUS output is given for 20 prescribed FOCUS periods (FOCUS working group, 1997). After a warm-up period of six years, the model will provide:

•	An annual summary in the case of annual applications

•	A biennial summary in the case of biennial applications

•	A triennial summary in the case of triennial applications

If, for example, biennial applications are used, the model will give results for the years 1907-1908 (period 1), 1909-1910 (period 2), etc.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Set Output options

Before you can make a graph, you have to make sure that PEARL generates sufficient information. This has to be done before running the model. You can:

•	Select variables for output.

•	Set the output depth(s)

•	Set the print interval

•	Set the output format

The print interval and output format can usually be kept at their default values.

Output control

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Run the model

After you have set the output options, make sure that you run the model.

The 'ResultsDetailed' column in the Browse box of the main form must be 'there' before you can create any User defined graph.

Running the model

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PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Create or Select a graph template
Create a graph template

If you want to make graphs with pre-set axes and titles, you have to create a graph template before entering the User defined Graphs form. Also, if you want to plot monitoring data in combination with simulation results, you have to use templates. To do this, select Graphs from the main menu, and then 'Graph templates'. Now:

•	Create a new template

•	Fill in the templates form

•	Close the form to return to the main form

To learn more, read the Graph templates page.

Graph templates

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Select one or more variables for output

You can now enter the User defined Graphs form, by pressing the 'Graphs, User defined' button on the main form. You will enter a form, where you can select:

•	one or more variables. The variables are grouped in the same way as the variables in the Output Control form.

•	One or more depths.

•	One or more substances.

You will find out that some fields are disabled and that you cannot mix certain type of graphs. To learn more, read the detailed information.

Control of user-defined graphs

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


View the graph
Create the graph

At this stage, PEARL has all the information for graphing. Press:

•	The Graph button to create a graph with automatic axes and titles

•	The Graph Using Template button to create a graph with user-defined axes and titles.

PEARL will run the graphical program XYWin for presentation. To learn more, follow one of the links.

Graph templates

The XYWin program

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Exporting the data

Once you have selected one or more variables for output, you can press the Export to File button. PEARL will ask for a file name and location. The following file format is used:

Time     Y1_Value    Time  Y2_Value  ….

…

Time     Y1_Value    Time  Y2_Value  ….

You can import the data in EXCEL for comparison.

The Time axis will depent upon the settings in the Output Control tab.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Graph titles

XY supports up to two graph titles. These titles will be plotted in the upperleft corner of the graph. If a legend is plotted as well, the titles will be plotted above the legend. The format of the title commands is:

TITLE_1 Text

TITLE_2 Text

Example:

TITLE_1 Concentration of atrazine in the groundwater

TITLE_2 (Maize in Hamburg)

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Axis text

Text will be centered along the axes. The format of the command is:

X_TEXT text

Y1_TEXT text

Y2_TEXT text

Example:

X_TEXT Days since start of the simulation

Y1_TEXT Concentration (mg/L)

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The legend

XY will automatically plot a legend if more than one data-series has been selected. You can use the legend command to assign appropriate texts.

LEGEND 'text of series 1' 'text of data series 2' …

Notice the quotes, which must be used to separate the various texts.

You can use the LEGEND_COLUMNS command to define the numbers of columns in a legend. By default, XY will plot all data-series in single column.

LEGEND_COLUMN NumberOfColumns

Example:

LEGEND 'Simulated concentration' 'Observed concentration'

LEGEND_COLUMNS 2

The NO_LEGEND command can be used to suppress the legend.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Plotting two axes

Different data series can be assigned different Y-axes. The lefthand Y axis is called the Y1 axis, the righthand axis is called the Y2 axis.

Example:

YAXIS_NUMBER 1 2

(the first dataseries is assigned to the lefthand axis, the second series is assigned to the righthand axis)

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Axis positions

You can plot the Y axis to the righthand side or to both sides of the figure:

Y1_RIGHT

Y1_BOTH

You can plot the X axis to the top of the figure:

X_TOP

By default, XY will plot a rectangle around a graph. If you want to suppress this, use the OPEN_GRAPH command.

OPEN_GRAPH

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Axis format

Sophisticated axis setting can be entered with the AXIS commands:

X_AXIS minimum [maximum] [major_divisions] [minor_divisions] [label_format] [axis_type]

Y1_AXIS minimum [maximum] [major_divisions] [minor_divisions] [label_format] [axis_type]

Y2_AXIS minimum [maximum] [major_divisions] [minor_divisions] [label_format] [axis_type]

Where:

•	Minimum refers to the minimum value

•	Maximum refers to the maximum value

•	Major_divisions refers to the number of tic marks

•	Minor_divisions refers to the number of secondary tic marks

•	Label_format can be used to format the numbers. Standard C or C++ notation must be used for this purpose.

•	Axis_type can be set to zero (normal axis) or one (logarithmic axis)

Example:

X_AXIS 0 200 4 5 %5.0f 0

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Plotting a zero line

The ZERO_LINE command can be used to plot a zero line.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Plotting additional data

The DATA command can be used to plot extra data-series.

DATA File_Name  X_Column X_Column

Where:

•	FileName is the name of the file with additional data

•	X_Column is the number of the column with X data

•	Y_Column is the number of the column with Y data

Columns must be tab or space delimited.

Example:

DATA atrazine.dat 1 2

A data-series will be created with the X values taken from column 1 and the Y values taken from column 2 in file 'atrazine.dat'.

Tip: Additional data-series can be used to plot observed data.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Plotting markers

Use the DRAW_MARKERS command to plot markers for each individual point a data-series. Use the MARKER_SIZE command to define the size of a marker. MARKER_SIZE 1 is the default value.

DRAW_MARKERS MarkerType_1 MarkerType_2 …

MARKER_SIZE Size_1 Size_2 ..

Example:

DRAW_MARKERS 0 1 2

MARKER_SIZE 1 1 0.5

A marker will be plotted for the 2nd and 3rd data-series. No marker will be drawn for the first data-series. A normal marker will be used for the second data-series. A smaller marker (half the normal size) will be plot for the third series.

Line and marker types

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Line types

Use the DRAW_LINES command to assign line types to the data-series.

DRAW_LINES LineType_1 LineType_2 …

Example:

DRAW_LINES 1 0 0

A normal line will be drawn for the first data series. No line will be plotted for the 2nd and 3rd data-series. Notice that this is only relevant if you plot a marker instead.

Line and marker types

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Line and Marker types

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Plotting observed data

The following command can be used to plot additional data-series with observed data. Save them in a separate template, and use it several times!

DATA  c:\projects\vreepeel\observ.dat  1  2

LEGEND Simulated Observed

DRAW_LABELS  0 1

DRAW_LINES  1 0

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


A FOCUS project

After running the focus wizard, the user interface has created a new project (or has added the new run(s) to an existing project). You will see that combinations that are not allowed (e.g. vines in Jokioinen) will not appear in the project. The newly created project has some important features:

•	All runs can have different application schemes (a pesticide may be applied at different dates in Greece than it is in Finland). After running the FOCUS wizard you can enter the application schemes form to change the application scheme of individual runs. PEARL offers the possibility to use so called relative application dates; i.e. the number of days before or after application.

•	You will see that many fields in a FOCUS run are disabled, i.e. they are fixed. Trying to change them will give an error message.

•	If you have made a mistake during the generation of the FOCUS runs, you can always remove the project by pressing - on the navigator in the projects form. The original components will not be removed - you can easily generate new FOCUS runs.

If you want to change parameters in a FOCUS run, make a copy before proceeding. Notice, however, that this is not an official FOCUS run anymore!

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Location in the FOCUS wizard
Location(s) in the FOCUS wizard

You can select from one of existing locations only. Use the > button to Select one Location. Use the >> button to Select all Locations.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Crops in the FOCUS wizard
Crop(s) in the FOCUS wizard

You can select from existing crops only. Use the > button to Select one Crop type. Use the >> button to Select all Crops.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The substance in the FOCUS wizard

You can select an existing substance only. Make sure that the substance has already been edited. If not press Cancel and read 'Getting Started'.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Application scheme(s) in the FOCUS wizard

You can an existing application scheme only. Select one scheme; different application schemes can be allocated to individual runs later. If an application scheme is not available, read the 'Getting Started' section first.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


The repeat interval

You must choose between annual, biennial or triennial applications. See also 'the repeat interval of applications'.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Numerical records

These records are meant for single numerical values, such as the initial groundwater level. Numerical records consist of  an input field (field 1), an identifier (field 2), an optional dimension field (field 3), and a comment field (rest of record). See the following example:

1.00          ZGrwLevSta  (m)  Initial groundwater level [0|50]

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Option records

Option records consist of the input field (field 1), an identifier (field 2) and a comment field (rest of record):

Penman        OptEvp           Evapotranspiration: Input, Penman or Makkink

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Date records

Date records consist of the input field (field 1), an identifier (field 2) and a comment field (rest of record). Dates are input in the format dd-mmm-yyyy. The following month names are valid: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov and Dec.

01-Jan-1980   TimStart         Begin time of simulation [01-Jan-1900|-]

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Soil properties

The input of soil properties starts with the definition of the soil profile in the SoilProfile table. Soil properties can then be input as a function of depth (interpolate option) or as a function of soil horizon (horizon option). In the first case, the values specified by the user are linearly interpolated onto the numerical grid given in the SoilProfile table. In the second case, the horizon definitions given in the table are used as a key. Soil property tables consist of the following lines: (i) the identifier line, containing the key-word 'table', followed by the input option (horizon or interpolate), the identifier field and the dimension, (ii) the actual input records (one for each soil horizon), and (iii) the obligatory line containing the word 'end_table'. Comment between the identifier line and the end_table line is illegal:

table horizon Rho         (kg.m-3)  Bulk-density of the soil [100|2000]

1    1310.0

2    1540.0

3    1640.0

4    1650.0

5    1650.0

end_table

Multiple soil properties can be input in one table. In this case, two extra lines are added to the header of the table. These lines contain the identifiers of the individual columns and the dimension for the individual columns. Consider the following example.

table  horizon SoilProperties

Nr     FraSand    FraSilt    FraClay    CntOm         pH

       (kg.kg-1)  (kg.kg-1)  (kg.kg-1)  (kg.kg-1)     (-)

1      0.92       0.05       0.03       0.0470        4.7

2      0.96       0.02       0.02       0.0080        4.4

3      0.95       0.03       0.02       0.0019        4.6

4      0.94       0.04       0.02       0.0014        4.6

5      0.93       0.05       0.02       0.0000        4.6

end_table

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Compound properties

Values have to be supplied for all compounds considered in a simulation run. First, the user has to specify compound names in the compounds table. Compound properties that are independent from the soil profile are input through a series of numerical records. Consider the following example:

70.00         KomEql_atra  (L.kg-1)    Coefficient for equilibrium sorption

40.00         KomEql_DEA   (L.kg-1)    Coefficient for equilibrium sorption

45.00         KomEql_DIA   (L.kg-1)    Coefficient for equilibrium sorption

Depth dependent compound properties are input through tables (SoilCompound properties) as described in the soil properties section:

table interpolate ConSysEql       (kg.m-3)

z        pest    DEA     DIA

0.0      0.0     0.0     0.0

5.0      0.0     0.0     0.0

end_table

Notice that the compound names are specified at the second line of the table.

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4


Crop properties

Crop properties are input in an equivalent way as compound properties. Consider the following example:

-10.0         HLim1_Maize   (cm)       Anaerobiosis point  [-100|0]

© RIVM, Alterra and PBL, 2000, 2002, 2006, 2010

PEARL (Pesticide Emission Assessment at Regional and Local scales) FOCUS version 4.4.4