11/10/2012 Spatial modeling of pesticide emissions to groundwater and surface water in the Belgian context Bernhard s e-mail : 30 minutes => 20 minutes + 10 minutes discussion and award for best debater!
11/10/2012 Spatial modeling of pesticide emissions to groundwater and surface water in the Belgian Flemish context N. Stuber, I. Joris, L. Van Esch, A. Gobin, J. van der Kwast, J. Bronders, P. Seuntjens
Setting up a spatial model for Flanders» Definition of critical areas with risk of pesticide concentrations > 0.1 µg/l in groundwater» Use of GeoPEARL model to assess the pesticide leaching potential on agricultural areas» Establishment of a spatial schematisation for calculations» Different test runs with defined spatial model parameterisation» Calculation of percentiles of leaching concentrations (20 years)» Plausibility checks and sensitivity analysis» Further improvements 11/10/2012 3
Spatial model in GeoPearl» Spatially distributed leaching model of the soil plant system (Pesticide Emission Assessment at Regional and Local scales)» Use on European scale for pesticide authorisation» Higher tier risk assessments» Meetings with Aaldrik within the project 11/10/2012 4
GeoPEARL model - setup» Hydrological model SWAP» Pesticide fate model PEARL Input files Plot def. Weather files Soil profiles ET parameters Spatially distributed parameters Files edited in standard applications Lower boundary cond. Drainage system Crop area per plot Output files 11/10/2012 5
Methodology-workflow Preparation of datasets Expert judgement Long-term daily weather Soil properties Lower boundary condition Agronomic practices Climate scenarios Soil scenarios GW depths Target crop(s) Creation of maps GIS Model parameter Leaching scenarios Plausibility checks Input files GeoPEARL Output files Probalility distribution 11/10/2012 6
Defining weather scenarios» MARS-STAT dataset, 50 x 50 km» Gridded ECA&D dataset 0.25 (E-OBS) (EU-FP6 project ENSEMBLES) Daily time serie 1981-2006 86 combinations 11/10/2012 7
Soil data sources Digital map of soil zones (1: 20.000; VLM 2007) 36 soil zones Digital map of soil series (1:20.000, VLM 2007) orig: 4.405 soil series Aardewerk (Noord) soil database Soil profile and horizon descriptions 11/10/2012 8
Soil profile data Aardewerk Noord PRNOORD ID (dig.map): Zone & serie number - 6.243 soil profiles - reduction to basis series ID: zone, profile & map number HORNOORD ~ 34.500 Horizon descriptions - Texture (Sand, Silt, Clay) - horizon thickness and deepness - ph KCl - Organic carbon OPPNOORD Soil properties for topsoil 11/10/2012 9
Defining soil scenarios 4.405 soil series Digital map of soil zones 36 soil zones + Digital map of basis soil series Digital map of basis soil series per soil zone 3.732 soil map entities + Soil profiles relevant for Flanders (Aardewerk) 6.234 profiles, ~ 34.500 horizon descriptions 536 soil map units Extraction of properties for dominant soil series, covering 80% of the area per soil zone Median profile per soil serie per zone 11/10/2012 10
GrwLevel U n s a t u r a t e d z o n e Defining soil scenarios - Description of soil map units» Description of every soil layer in every soil map unit with: 30 cm Horizon 1 2.5 cm 5 cm» Soil physical properties Horizon 2» Soil hydraulic properties (PTFs) 100 cm Horizon 3 10 cm 300 cm Groundwater 11/10/2012 11
bottom flux (cm d -1 ) gw-level (cm) Fixed gw-level (Boundary Condition constant head) 0-50 0 500 1000 1500 2000 2500 3000 3500 4000 P ET -100-150 -200-250 -300 gw-level Time (days) bottom flux 0.1 0-0.1-0.2-0.3-0.4-0.5-0.6-0.7-0.8 0 500 1000 1500 2000 2500 3000 3500 4000 Time (days) 11/10/2012 12
bottom flux (cm d -1 ) gw-level (cm) Fixed bottom flux (BC constant flux) 0-50 -100-150 -200-250 -300 0 500 1000 1500 2000 2500 3000 3500 4000 Time (days) 0.1 0-0.1-0.2-0.3-0.4-0.5-0.6-0.7-0.8 0 500 1000 1500 2000 2500 3000 3500 4000 Time (days) 11/10/2012 13
14/04/1993 14/04/1994 14/04/1995 14/04/1996 14/04/1997 14/04/1998 14/04/1999 14/04/2000 14/04/2001 14/04/2002 14/04/2003 14/04/2004 14/04/2005 14/04/2006 14/04/2007 14/04/2008 Example gw level check Shallower gw-table predicted Recharge: 240 mm/yr! plot8_11zeg 1 0.5 0-0.5-1 -1.5-2 -2.5-3 -3.5 diepte_tov_meetpunt Calculation -2m 11/10/2012 14
Lower boundary condition» Map on mean highest groundwater depths (van der Kwast et al.,2009) Definition of fixed groundwater level condition 0-1 m 1-2 m 2-3 m > 3 m Definition of a free drainage condition for areas with GrwLev > 3 m 11/10/2012 15
Developed scenarios fixed groundwater levels Soil map (536 units) Climate (MARS+ECA&D) +» Groundwater depths (4 classes) 0 1 m 1 2 m 2 3 m > 3 m Groundwater depth map (4 classes) Fixed GrwLevels & Free drainage (> 3 m) 1434 unique combinations 11/10/2012 16
Leaching concentrations northwestern part of Flanders» Spring application: 0.7kg D/ha» Crop type: maize» Time period: 20 yrs» Evaluation depth: 1 m b) 90th percentiles of leaching concentrations c) topsoil sand content d) topsoil organic matter content. 11/10/2012 17
90th and 50th percentiles of leaching concentrations» Substance properties: solubility in water, sorption to OM and persistence in soil» Spring application: 0.7kg D/ha» Crop type: maize» Time period: 20 yrs» Evaluation depth: 1m and 50 cm 11/10/2012 18
Sensitivity analysis % of total area of Original GrwLev map Original GrwLev map +30 cm a Original GrwLev map + 50 cm b 70 Evaluation depth 1 m 70 cm 50 cm 1 m 70 cm 50 cm 1 m cm 50 cm conc. <0.1 (μg/l) 97.8 98.1 96.8 98.5 98.7 96.2 98.8 98.9 96.3 conc. >0.1(μg/L) 2.2 1.9 1.8 1.4 1.2 1.6 1.2 1.0 1.5 SWAP missers c 0.02 0.06 1.39 0.08 0.10 2.22 0.02 0.03 2.21 highest conc. (μg/l) 0.61 0.60 0.6011/10/2012 0.61 0.60 0.60 0.53 0.44 0.35 19
Conclusions» Flemish GeoPEARL approach: 1434 leaching scenarios that cover environmental variability and simulate spatial pattern of pesticide leaching» Identification of vulnerable areas could be used for further higher tier risk assessments» Importance of lower boundary conditions» Importance of soil organic carbon is highlighted => further need for spatial information, depth distribution and time dynamics» Potential land use (maize only) implemented => crop map and application rate from surveys 11/10/2012 20