Towards a tool for dimensioning grass-covered buffer zone to limit the flow of phytosanitary products transferred by runoff. Scenario tests

Abstract

Vegetated strips can be useful in order to limit pesticides fluxes transfered from agricultural fields towards surface waters. However, these structures must be judiciously positioned and well proportioned to be really efficient. In this article, we assess the efficiency of vegetative strips to limit surface runoff in contrasted situations, representative of different parts of France. The modelling tool is HYDRUS 2D, which represents variably saturated flow in soil. Three agro-pedo-climatic situations were investigated : 1 - La Morcille, in a vineyard area near Lyon, with very permeable soils and intensive runoff events, 2 – Le Pays de Caux, where soils are very sensible to hortonian surface runoff, and 3 – La Jaillière, near Brittany, where soils are often hydromorphic. Results show different trends for each ensemble of scenario, representative of a given agricultural area. They also get prominence to the fact that it remains necessary to design each vegetative strip individually, taking into account the very local context. The more influent variable were identified ; this allows to give an order of magnitude of the efficiency of a vegetative strip to limit surface runoff, without a complete simulation, given its own characteristics and those of incoming runoff.