Monitoring the transfer of phytosanitary products on watersheds and example of global modeling

Abstract

This article provides information on pesticide transfer in three watersheds of 4 to 12 km² in France. It shows that the maximum concentrations are often related to the first main rainfall events occurring after the application and that they can vary from year to year. The amount of pesticide measured at the outlet was less than 1% of the application. The GLEAMS (Ground water Loading Effects of Agricultural Management Systems) model was applied to simulate pesticide mobility on small watersheds. The results show that this kind of model can't predict accurate concentrations but could be used as a screening model to classify pesticide according to their mobility in runoff, for given scenarios. A particular attention should be given to the selection of the sensitive parameters.