Miles Vulnerability assessment of groundwater monitoring...

Vulnerability assessment of groundwater monitoring data and context setting for EU-wide, zonal and national registration

Ben Miles, BASF SE

17th European Modelling Workshop, Vienna22.10.2014

Background: FOCUS GW (European Commission 2014, coming into force in 2015)

For use of groundwater monitoring data at Tier 4 (EU or country level) there is requirement for quality criteria to be met, particularly

good characterisation of groundwater hydrology

demonstrating connectivity between treated topsoil and the point of sampling of the groundwater

demonstrating that relevant products have been used for a sufficient number of years in relation to the expected solute travel time to the aquifer (estimation should be robustly supported)

Overall exclusion of false negatives (and false positives)


Background: FOCUS GW (European Commission 2014, coming into force in 2015)

At EU level, “a safe use” must be demonstrated to exist within the EU, covering a significant area in the context of one or more of the representative uses assessed

Reservations remain whether current knowledge on groundwater hydrology at the EU level, would be sufficient to use monitoring data to ever conclude that “safe use” might cover an extensive area for the EU evaluation


How to address the requirements for use ofmonitoring data?

How can we address the quality criteria at the scale of individual monitoring sites?

Having demonstrated leaching vulnerability and connectivity of sampledwells to treated fields and excluded false negatives, how can we assessrepresentativity for a wider area of use (i.e. demonstrate safe use)?

Is lack of knowledge on groundwater hydrology at the EU level a significant problem?


Combined approach working at different spatial scales


Local scale:Monitoring site analysis

Combined analysis for RA showing relevance of monitoring data and setting monitoring sites/data in context for wider usage area (EU, Zone, Country…)

Large scale:Context setting, wider use area

What we use

What we want to achieve

What we get

What we do

monitoring site data monitoring results

monitoring site data GIS data

detailed hydrogeological site characterisation farmer surveys for product usage vulnerability assessments for wells Site specific modelling (soil column & aquifer)

GIS spatial analysis GW vulnerability mapping using both site

specific and latest EU-wide spatial data Relevance assessment in EU context

Representativeness in spatial context Comprehensive analysis:

use area – gwm sites – FOCUS scenarios

Vulnerability of monitoring sites Relevance of monitoring data Information on leaching behaviour

Work at two scales

What we use

What we want to achieve

What we get

What we do

In relation to current tiered assessmentscheme


Approach combines Tier 4 with Tier 3b, includes elements of 3c and 3d

Monitoring site characterisation:Vulnerability and product applications

Monitoring site might be a monitoring well from existing public network ordedicated well installed at edge of field

For a monitoring well from existing public network the characterisation depends on available data


Geological profiles,

hydrogeological characterisation,

identification of relevant fields and

farmer surveys for product applicationhistory









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Construction DetailsBorehole Lithology

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Slotted casing

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-4.4

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Gravely sand

-6.0

Boulder Clay

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+0.3

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Solid casing

Bentonite fill

Filter gravel

Slotted casing

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Bentonite fill

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Protective cover


-4.4

Man made

Gravely sand

-6.0

Boulder Clay

Ground surface

-0.8

+0.3

+0.8

Solid casing

Bentonite fill

Filter gravel

Slotted casing

Sump

Bentonite fill

-5.0

-4.5

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-6.0

-1.3

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0.0

-5.15

Protective cover


-4.4

Man made

Gravely sand

-6.0

Boulder Clay

Ground surface

-0.8

+0.3

+0.8

Solid casing

Bentonite fill

Filter gravel

Slotted casing

Sump

Bentonite fill

-5.0

-4.5

-5.0

-5.5

-6.0

-1.3

-1.5


0.0

-5.15

Protective cover


-4.4

Man made

Gravely sand

-6.0

Boulder Clay

Ground surface

-0.8

+0.3

+0.8

Solid casing

Bentonite fill

Filter gravel

Slotted casing

Sump

Bentonite fill

-5.0

-4.5

-5.0

-5.5

-6.0

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catchment

GW Flow

Monitoring site characterisation:Site specific modelling

Is the monitoring timeframe and sampling interval appropriate?

Can measured concentrations at the monitoring well be linked to known productapplications?


CWeather, crop andapplication data

Leachingsimulation

GW flowHydrogeological data

time

GW flow andtransport model

Soil data

Monitoring site characterisation:Site specific modelling

Leaching models (e.g. PEARL) parameterised for the treated fields give us expected timeframe andconcentration signal for breakthrough at groundwater surface after application

To look at the expected concentration signal at the well for the monitoring period and make the link between measured concentrations and product applications 2D (or 3D) flow and transport simulationsfor the aquifer are appropriate

Output of field-specific leaching simulations used as boundary conditions for transport simulationsalong the flowpath to the well


GW Well

Monitoring site characterisation:Summary

Detailed characterisation of monitoring sites addresses quality criteriarequirements for groundwater data, especially

good characterisation of groundwater hydrology

demonstrating connectivity between treated topsoil and the point of sampling of the groundwater

demonstrating that relevant products have been used for a sufficient number of years in relation to the expected solute travel time

Overall exclusion of false negatives (and false positives)


Context setting, wider use area:Mapping monitoring locations to land use


Demonstrate that monitoring locationsare in areas with intensive cultivationof target crop relative to proposedusage area

Product monitoring sites

Context setting, wider use area:Mapping monitoring locations to climatic zones


Demonstrate that monitoring locationscover a range of climatic zones in Europe, relative to proposed usagearea

Product monitoring sites

Context setting, wider use area:Spatial modelling


Approach: account for relevant processes of pesticide fate and movement through soil surface spatially distributed modelling

MetaPEARL: Metamodel of EuroPEARL (process based model) Consideration of sensitive processes and

parameters which are available as map data in GIS Climatic parameter: precipitation, temperature Soil parameters: water content, water flux,

organic matter, bulk density Substance parameters: DT50 and Kom

Proposed in FOCUS guidance for higher-tier exposure assessments

Context setting, wider use area:Spatial modelling


Metamodel: Calculate relative leaching vulnerability for all OSR-relevant areas in EU

Context setting, wider use area:Determining relative vulnerability of sites


Determine where the monitoringsites are positioned in relationto the vulnerability distributionfor all OSR producing areas bye.g. climate zone

Context setting, wider use area:Summary


Context setting can be used to assess representativity of monitoring datafor a wider use area (country, zone, EU level)

Tier 3b is considered to be higher in the assessment scheme than Tiers 3c and 3d, taking a position between these and Monitoring Data at Tier 4

Tools for the assessment exist within the current regulatory framework(e.g. MetaPEARL)

For reliable risk assessment spatial datasets need to be of high qualityand transparent. Consensus needed on which data to use.

Conclusion

Combined approach of site assessment and spatial modelling fulfilsrequirements of guidance for monitoring data to be used in the registrationprocess and fits in current framework of tiered assessment

To fulfil the quality criteria for monitoring data, dedicated edge-of-fieldmonitoring wells have often advantages over wells from existing networks, however both can be used

If monitoring is carried out in generically vulnerable groundwater situationsit is not necessary to have detailed knowledge of hydrology at EU scale –it is sufficient to consider the potential for substances to leach from the soilcolumn.

Usefulness of spatial modelling depends on having agreed datasets ofsufficient quality and appropriate models


Miles Vulnerability assessment of groundwater monitoring...

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