Downscaling method for estimating the potential for nitrogen contamination of surface waters

Abstract

This paper presents a model to evaluate the contamination potential due to intensive agriculture of surface water in the Save watershed (affluent of the Garonne). The originality of the model resides in the use of a very detailed spatial object, the pixel, adapted to many working scales. The studied land, situated in the hillsides of the Gers department, is constituted by three different size watersheds (Save, 1150 km2, Boulouze, 70 km2, and Montoussé, 6 km2). Indicators about agriculture and environment, built the model. They describe the vulnerability of environment and the agricultural pressure. The association of these indicators on a pixel indicates the contamination potential of superficial water. The diffuse pollution of nitrates illustrate these works. The specific model creating is called AZOTOPIXAL. The created method is the continuation of preceding works, which were oriented towards pesticides (PHYTOPIXAL model) and contributes to the actual researches on space scaling management.