Demo of GeoPEARL

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Transcript Demo of GeoPEARL

A spatially-distributed model of pesticide leaching Aaldrik Tiktak

Outline of presentation

• Why spatially distributed modelling?

• What is GeoPEARL?

• How is a GeoPEARL assessment carried out?

• Which are the main model outputs?

• Selected Results and Examples • Questions?

• Overview of the User Interface http://www.pearl.alterra.nl

Why spatially distributed modelling in registration?

Explicit consideration of the variability of the leaching process: • where are the vulnerable regions?

• Are specific areas (e.g. drinking water abstraction areas) sufficiently protected?

Leaching in drinking water abstraction areas http://www.pearl.alterra.nl

Why spatially distributed modelling in registration?

Explicit calculation of ‘realistic worst-case conditions’: • calculation of percentiles of the leaching concentration in space • more realistic choice of standard scenario’s, no need for safety factors in registration Standard Scenario http://www.pearl.alterra.nl

What is GeoPEARL?

• GeoPEARL is a spatially-distributed model of pesticide leaching to the groundwater and surface waters in the Netherlands. The core of the GeoPEARL consists of PEARL itself.

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The PEARL model - a 1D-column SWAP hydrology

preci pitat ion irrigati on t rans pirati on c rop c alendar s oil ev aporat ion ev aporat ion of int erc ept ed water t hroughf all ponding s urf ac e run-off

PEAR L pesticide fate

dis s ipation at the c rop c anopy v olati lis ation pes tic ide upt ake heat f low water uptak e by plant root s s oil wat er f luxes depos iti on applic at ion was h of f t rans form ation s olid-liquid gas partit ioning c onvec t ion dis persion dif fus ion injec t ion f luct uati ng groundwater lev el lat eral dis c harge to dit ches and f ield-drai ns s eepage leac hing http://www.pearl.alterra.nl

Position of column in landscape PEARL 1D column field ditches water courses < 3m water courses > 3 m Groundwater table Drainage into local surface waters Leaching into the regional groundwater

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Why a complex model??????

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The plot appraoch

• PEARL is run in a GIS context for a large number of unique combinations (plots) of soil, climate, land-use and hydrogeological units.

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Derivation of the unique combinations:

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Obtaining the lower boundary of SWAP:

• Lower boundary condition is a prescribed flux condition (so-called ‘Neumann condition’); • Lower boundary of SWAP is upper boundary of National Groundwater Model; • Start with NAGROM and a simple unsaturated zone model; • Adjust the boundary flux by running NAGROM and SWAP iteratively; • Wait until convergence is reached.

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Plots are represented by a single vertical column: A plot

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Basic soil properties in GeoPEARL Slightly acidic sandy soils (‘higher part’)

pH-KCl!!!!!

Clay soils with near neutral pH-values (‘lower part’) Acidic peat soils

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How are GeoPEARL assessments carried out?

• GeoPEARL is run for 250-6405 plots, depending on spatial detail wanted; • The model is run for the area of potential usage only. This area is assumed equivalent to the area of the crop(s) for which a registration is requested; • For each plot and crop-type, the model is run for 26, 46 or 66 years (FOCUS procedure); • For each plot the median leaching concentration in time is extracted and put into a map.

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To be specified by the user:

• Substance properties (start with standard dossier) • Application schedule • Number of plots (i.e. spatial detail wanted) • One or more crops for which a registration is requested http://www.pearl.alterra.nl

More attention for relationship between soil properties and substance properties:

• DT

in top-soil specified as a function of clay content, pH and organic matter content

DT DT

50 , 50 ,

plot plot

 

50 , min if

50 , min 

50 ,

plot



50 , max

50 ,

plot



50 , min

50 ,

plot DT

50 ,

 

f om

(

m om



m om

) 

f l

(

m l



m l

) 

f p

H (

H 

)

50 ,

plot



50 , max • K

specified as a function of organic matter and pH:

K F,eq



m om K om

eq, ac 1  

K om

ba M M ba

ac 10

H -

Ka 

M M ba

ac 10 pH -

Ka 

H or as a function of other properties:

K F



K F

, 0 

m om K om



m sand K sand



m silt K silt



m clay K clay



c sox K sox

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More attention for relationship between soil properties and substance properties:

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The target variable produced by the model:

• The 90 th percentile in space and the 50 th percentile in time of the leaching concentration at 1 m depth at the area of

(potential) usage

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Further model outputs:

• Maps and frequency diagrams of terms of the water balances • Maps and frequency diagrams of terms of the substance balances, including the leaching, drainage and volatilisation fluxes • Maps of percentiles and frequency diagrams of the leaching concentration in time • Tables of balance terms http://www.pearl.alterra.nl

Example 1: Comparison of leaching of two substances

Ordinary substance pH-dependent sorption High pH Vulnerable sandy soils

Opposite spatial patterns!

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Example 2: Comparison of drainage and leaching

Drainage fluxes are highest in clay and peat soils...

Leaching fluxes are highest in sandy soils...

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Some conclusions from previous examples:

• Drainage fluxes are generally higher than leaching fluxes.

• For ordinary substances, drainage dominates in the peat and clay soils and leaching in sandy soils.

• The leaching pattern can be quite different for non-ordinary substances (e.g. substances with pH dependent sorption) http://www.pearl.alterra.nl

GeoPEARL considers the area of potential usage:

• Pesticides are usually authorised for particular crops; • The new decision tree therefore considers the area of potential usage, approximated by the area of crops for which a registration is requested • GeoPEARL is distributed with a database of areas for 24 major crops • All results are presented for the area of potential

usage

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GeoPEARL crops are not hydrologically different

• During the derivation of the UC’s, only four crops were included (grass, mais, potatoes and forest); • For each plot, the dominant crop is used. Hydrological parameters are assigned to these crops; • The 24 GeoPEARL crops are used for pre processing only; i.e. for calculating the area of use.

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Effect of area of use on pesticide authorisation (1)

Maize is grown on slightly acidic sandy soils Potatoes are grown on light sandy clay soils and in ‘the Veenkolonien’ http://www.pearl.alterra.nl

Effect of area of use on pesticide authorisation (2)

Slightly acidic sandy soils Light sandy clay soils and ‘the Veenkolonien’ http://www.pearl.alterra.nl

Substance with pH-dependent sorption behaviour

Effect of area of usage on authorisation (cntd.)

Unsafe in potatoes Safe in maize http://www.pearl.alterra.nl

Some conclusions from previous section:

• GeoPEARL explicitly considers the variation of the leaching process, so that it is now possible to evaluate the leaching for different crop types • Consideration of the area of usage can have a strong effect on the authorisation decision • It is extremely important to investigate the relationship between pesticide properties and soil properties http://www.pearl.alterra.nl

GeoPEARL assessments versus assessment items

• A notifier may wish to register for several crops; • For each crop, GeoPEARL must be run separately; • Combination of crop and application scheme is an assessment item; • The three items together form an assessment; • The 90 th percentile is calculated for the combination of the three crops, i.e. for the assessment.

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The GeoPEARL database

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Reduction of computation time by using zones:

• To reduce the computation time, plots are taken together; • Clusters of plots are called ‘zones’.

Plots Zones 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 SLICE 1 2 2 3 5 4 5 1 4 5 1 2 3 4 1 2 3 4 Plot without relevant crop Plot with relevant crop http://www.pearl.alterra.nl

Slicing is done on the basis of ‘vulnerability’

• The normal Arc/Info slice operation clusters neighbouring cells; • We cluster plots with adjacent vulnerability indexes; • This will give a more reliable estimation of the 90 th percentile, because we sample in each class of the cumulative frequency distribution.

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The vulnerability index for ordinary substances:

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How many plots must be included in an assessment?

these two are different!

almost no difference http://www.pearl.alterra.nl

How many plots must be included in an assessment? (cntnd.)

More plots = more detail, but 250 plots is generally enough...

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250 versus 6405 plots

10 1 0.1

0.01

spring 0.001

0.0001

0.00001

0.0001

10 1 0.001

0.01

0.1

GeoPEARL_6405 (ug/L)

0.01

0.001

1 10 0.0001

autumn 0.00001

0.00001

0.0001

0.001

0.01

0.1

GeoPEARL_6405 (ug/L)

250 plots is generally enough...

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1 10

Some conclusions from previous section:

• The maximum number of zones is 6405 (which is equal to the number of plots); • A first impression of the leaching pattern can be obtained with less plots (e.g. the 30 as used in this course); • At least 250 plots are required for an accurate estimation of the 90 th percentile. This is the

minimum number for a final submission.

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Other uses of GeoPEARL

• GeoPEARL has been combined with a database on pesticide usage in order to calculate the actual pesticide loads into surface waters and groundwaters.

• Evaluation of policy plans... • A European version of GeoPEARL (called EuroPEARL) has been developed • EU registration in zones... http://www.pearl.alterra.nl

EuroPEARL example: 80 th percentile of the leaching concentration of FOCUS substance D

High leaching risk

Hotspots occur everywhere in Europe

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Possible scales…

Catchment http://www.pearl.alterra.nl

Final remarks

• A model is now available that can be used to assess the leaching into the groundwater and the drainage into surface waters at a regional-scale • The model is operational for: • the Dutch registration procedure • evaluation of policy plans http://www.pearl.alterra.nl

The Graphical User Interface

GeoPEARL User http://www.pearl.alterra.nl

First install the program….

Download geopearl_1_1_1.exe

from the address http://www.pearl.alterra.nl.

Archive this application Logon with administrator rights Run geopearl_1_1_1.exe to install GeoPEARL Launch GeoPEARL to install Interbase If FOCUS PEARL 2.2.2 is installed: launch FOCUS PEARL as well Logon with your own user name Start using GeoPEARL; register at the PEARL website http://www.pearl.alterra.nl

To be specified by the user:

Getting started with the User Interface

Add o r e dit a substa nce .

Par ameters must be gi ven for pare nt substances an d for metabol ites Add o r e dit app licati on schemes.

Each assessmen t ite m may have i ts own a pplication sche me.

Use the wizard to ge nerate assessments.

An assessmen t consists o f a sin gle substa nce a nd one or asse ssment items.

Sel ect asse ssments for executi on and push the ca lcu late b utton to start the simulations http://www.pearl.alterra.nl

GUI step 1: Main form

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GUI step 2: Edit substance properties

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GUI step 3: Edit application schedules

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GUI step 4: Run wizard, select substance and resolution

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GUI step 5: Run wizard, select crops and applications (i.e. add items)

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GUI step 6: Run GeoPEARL

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The model is running….

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GUI step 7: Select output - Assessment as a whole

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GUI step 7: View output - Assessment as a whole

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GUI step 8: Select output - Assessment item

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GUI step 8: View output - Assessment item

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GUI step 9: View report (assessment as a whole)

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GUI step 10: Analyse the output

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GUI step 10: Analyse the output

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Demo of GeoPEARL

Transcript Demo of GeoPEARL

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