Annual nutrients export modelling by analysis of landuse and topographic information: case of a small Mediterranean catchment
Résumé
The preservation of water bodies from eutrophication implies accurate estimation of phosphorus
and nitrogen loads and the control of nutrient production on a catchment scale. In this paper, a simple tool for
the modelling of annual nutrient loads is presented. It is implemented in ARC/INFO GIS using Arc Macro
Language (AML). The use of a GIS is justified as the spatial characteristics of the catchment area (land use,
industrial wastewater location) dictate water quality. The annual nutrient loads are worked out on the
catchment scale, using existing GIS routines together with specific routines developed in AML for
hydrological and water quality modelling purposes. The catchment area is divided into hydrological
subcatchments with relatively homogeneous spatial characteristics. Each subcatchment is linked to a
specific nutrient export potential. These nutrient loads, calculated on a subcatchment-by-subcatchment
basis, are conveyed to the outlet of the catchment and allow annual nutrient load estimation. A comparison
with a water monitoring study is conducted to verify the adequation of modelling results for phosphorus and
nitrogen loads.