Estimation of pesticide emissions to surface and groundwater in Belgium using the SEPTWA95 model
1997
Pussemier, L. | Beernaerts, S. (Institute for Chemical Research, Tervuren (Belgium))
SEPTWA95 (System for the Evaluation of Pesticide Transport to WAters) is a screening model that has been developed for predicting pesticide emissions to surface and groundwater in the various river basins from Belgium. The most important input data for the model are the amount of pesticide applied, the period of application, the persistence (DT50) and mobility (Koc) parameters, and the pedoclimatic characteristics (type of soil, rainfall). The model considers several transport processes (associated to several emission factors) to surface waters such as direct transport (following the rinsing of sprayers and spills), drift, run-off and drainage. Transport to groundwater is assumed to be done by leaching through the soil profile and is quantified using a relationship existing between persistence-mobility parameters (the so-called CUS index) and the amounts leached below one meter depth as predicted by the Dutch model PESTLA. The pesticides selected for this study belong to the most intensively used in agriculture as well as in urban environments (non agricultural uses). Data on their precise uses (reference year 1993) were obtained from the Ministry of Agriculture as through different surveys among pesticide users and retailers. Input data were mostly introduced at the municipality level (land use and amounts of pesticide applied) whereas the outputs were given at the river basin scale (36 basins for the whole country). The first results obtained allow to classify the pesticides according to the total and regional emissions values. Attempts were made to compare these outputs to the measurements carried out for several pesticides in different rivers and the fit between observed and predicted values was considered as fairly acceptable taking into account the number of approximations needed for developing such a screening model.
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