Présentations Colloques

Oral Presentation
5.04
Session 5.04: Emerging contaminants in the water cycle and risk to Groundwater
Bronders Jan
Spatially distributed modelling of pesticide leaching in Flanders
Pesticides are widely used to protect plants from harmful organisms, and to increase agricultural production. These pesticides can be beneficial for plant protection but, at the same time, can also have a damaging effect on humans, animals and the environment. In the soil system, pesticides can degrade or adsorb to soil or organic particles. Once in the groundwater, pesticides and their metabolites can persist for years. The movement of pesticides through the soil to the groundwater, also referred to as leaching, is therefor of particular concern. To assess the vulnerability of aquifers in Flanders we have set-up a physically based spatially distributed leaching model for Flanders using GeoPEARL. In this study we describe how existing national and European datasets were used to prepare the input data for the model and how the model can be used to identify areas with a high leaching risk. With these results, guidelines can be developed to reduce pesticide leaching and protect groundwater resources.**The main challenge of setting-up a spatially distributed leaching model, was the generation and parameterisation of a spatial schematisation, which covers the spatial variation and heterogeneity of the Flemish agricultural landscape. Different national and European spatial databases, containing information on soil, weather, land use and the groundwater system, were collected and processed. The model results were checked by comparing long-term averages of substances and water balances with existing measurements or results from other models.**The Flemish spatial leaching model gives insight in regional differences in the vulnerability of the Flemish aquifers with regard to pesticides and the sensitivity of the different variables with respect to groundwater leaching. The model can be used to guide groundwater monitoring strategies and assess the impact of for example climate changes, alternative agricultural management practices or alternative crops on the leaching of pesticides.
Belgium