Building risk indicators of surface water contamination by pesticides at the small catchment scale. Taking into account spatial and temporal dimensions

Building risk indicators of surface water contamination by pesticides at the small

catchment scale. Taking into account spatial and temporal dimensions. Support

for risk assessment and management : MIRIPHYQUE project. 2011-2013

2 Innovative approaches for the management of environmental risks from plant protection products . 26-28 october 2011

Background

Only few indicators exist at the catchment scale (Devillers et al., 2005).

But there are still needs for : tools to assess catchments’ potential to

contaminate surface water, methods to base the choice a priori between

several mitigation solutions.

… which take into account spatial distribution of pesticides uses and existing or potential buffer zones.


Project general aim

To design a method in order to assess the potential of surface water contamination by pesticides at the small catchment scale, taking into account :spatial and temporal dimensions,

man made structures’ influence on pesticides fluxes (buffer zones, ditches, banks, roads),

HypothesisNumerical simulation models versus Indicators

Hybrid method, associating indicators and hydrological modelling at the catchment scale


Methodology

Numerical modelling at the different relevant scales Organization of simulated time-chart results in a spatio-

temporal warehouse Modelling results aggregation ; statistical analysis of results,

comparison with observed data.

Implementation on two catchments with contrasted agro-pedo-climatical characteristics: la Fontaine du Theil et la Morcille

Catchment typology (geology, pedology, climate, agricultural practices) in order to prepare the adaptation of developed tools from one catchment to another (similar) one.


Methodology

Aggregating, at the catchment scale, results from modelling at the field scale, for “typical” fields and “typical” agro-pedo-climatical scenarii.

In order to lead to water quality “indicators”, CdF, and to compare them to observed data (chemical or biological data)

Virtual example of resulting indicators :

Concentrations exceedance durations

T = return period

Duration

Concentration

T = 4 monthsT = 10 monthsT = 2 years

g/L

1 h 1 day 1 week 1 month

Duration

Concentration

T = 4 monthsT = 10 monthsT = 2 years

g/L

1 h 1 day 1 week 1 month

x


Global chart

EIS « Pesticides »MetrologyCatchment descriptionAgricultural practicesTopological connections

« Field » warehouseField scale modelling results (discharges end concentrations time-charts, surface and subsurfaceRésultats

« Man made structure » warehouseRatio of pesticides fluxes reduction, transfer fromsurface to siubsurface

« Catchment » warehouseCatchment agregation results : discharges and concentration time-charts

Typology scenarii

Field typology (slope, soil ..)

Pesticides use strategy (date, dose ..)

Climate (dry year, wet year ..)

Field use

Plot scale model

Man made structure model

Hydrological model

Field use distribution (cultures et man made structures

Statistical analysis

Risk indicators(CdF)

EIS « Pesticides »MetrologyCatchment descriptionAgricultural practicesTopological connections

« Field » warehouseField scale modelling results (discharges end concentrations time-charts, surface and subsurface é

« Man made structure » warehouseRatio of pesticides fluxes reduction, transfer fromsurface to siubsurface

« Catchment » warehouseCatchment agregation results : discharges and concentration time-charts

Typology scenarii

Field typology (slope, soil ..)

Pesticides use strategy (date, dose ..)

Climate (dry year, wet year ..)

Field use

Plot scale model

Man made structure model

Hydrological model

Field use distribution (cultures et man made structures

Statistical analysis

Risk indicators(CdF)

Field scale modelling results (discharges and concentration time charts, surface and subsurface)


Methodology : Workpackage 1

Physical modelling at the relevant scales1.1 Defining pesticides uses scenarii

1.2 Field scale modelling

1.3 Man made structures modelling

1.4 Catchment scale modelling

Fontaine du Theil :• Assessment of hydrodynamical characteristics of soil layers .


Workpackage 1

La Morcille site0

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Organisation type des sols sableux sur

altérite (UTS 1)

Organisation type des sols sableux sur granite

fracturé (UTS 2)

Sandy soils upon weathered granite (UCS 1)

Hydrodynamical characteristics (K-Psi-Theta) Bimodal porosity.


Workpackage 1

Fontaine du Theil. Simulation at the field scale with MACRO (Jarvis et al, 1994)

Brown non hydromorphic soil.


Methodology : Workpackage 2

SI E Pesticides - Analysis SubModel

Activités Agricoles

Bassin Versant

Activités Métrologiques

Organization of simulated time-charts in a spatio-temporal warehouse

2.1 Developing a conceptual model to represent data

2.2 Designing a data warehouse for numerical modelling results

Unités surfaciques

Unité Linéaire

Connectivité hydrologique

Elément Ponctuel

Elément Ponctuel de Connexion

Elément Surfacique

Elément Linéaire

0 ..1

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NoeudReprésentation

E lément P onctuel de C onnexion

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T ronçon E lémentaire

Segmentation Linéaire

E lément L inéaire

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U nité Homogène A val

Connexion Aval

Ligne d'échange

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U nité Homogène A val

Connexion Amont

Noeud A mont *

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Ligne d'échange A val

Connexion Amont

U nité Homogène A mont

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Noeud A val

Connexion Aval

U nité Homogène A mont

T ronçon E lémentaire A mont

Connexion Aval

Noeud A val

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1Noeud A mont

Connexion Amont

T ronçon E lémentaire A val

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* T ronçon A mont

Connexion Aval

Ligne A val

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0 ..2Ligne A mont

Connexion Amont

T ronçon A val

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E lément SurfaciqueRedécoupage Spatial

U nité Homogène

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Unité Homogène

Tronçon Elémentaire

Ligne d'échangeNoeud

Homogeneous unit 1

Vegetative filter strip

Exchange linesExchange coefficients(surface, subsurface)

Homogeneous unit 2


Workpackage 2

• 643 outlets

simplification• Outlet trees• Field deconnection by

hedges

Alternative solution : SACADEAU (tree of fields outlets)


Methodology : workpackage 3

Aggregation at the catchment scale3.1 Design of the catchment scale aggregation method

3.2 Validation of « SACADEAU » tool on La fontaine du Theil

3.3 Sensitivity analysis at the different modelling scales ; reflection about implementation on other catchments

3.4 Comparison with existing data


Workpackage 3

Field 3 : type « brown soil », slope 3%Soil occupation : cornPost emergence use of pesticides

Field 5 : type « hydromorphic soil », slope 1%Soil occupation : winter wheatPre emergence use of pesticides

Vegetative filter strip.Efficiency varying with time

C(outlet, t) = (f(field, buffer zone, t))surfacesubsurface

Data warehouse Simulation results ; year 2000


Conclusion

• First year of the project. Next step : finalization of simulation results warehouse ; aggregation.

• Project which will lead to a method having both advantages of numerical simulations AND indicators …


Thank you for your attention

Thanks for funding to :

Documents

Building risk indicators of surface water contamination by pesticides at the small catchment scale. Taking into account spatial and temporal dimensions