Geographic information systems and models to determine the non-point pollution hazard in a river basin

Abstract

A method of analysis of non point pollution risks for a watershed unit is developed with a GIS and a model. The basis hypothesis is to consider nitrogenous plot profiles in autumn as the nitrate leaching risk index. They result of the pollutant pressure involved by agricultural practices and they induce a variable intensity pollution according to land sensibility. The parameters which are to be used in the risk index have been determined with a data analysis (follow-up of agricultural practices). The approch is first developed at field scale, and then on the watershed unit.