Agricultural land use and trophic state of the Lake Vico (Central Italy)

The Lake Vice Basin (Central Italy) has already been a subject for previous studies, mostly aimed to define planning criteria, based on territorial processes. Results underlined the environmental peculiarities of the place, first of all the lake itself, whose trophic state is growing up, due mostly to heavy soil erosion and related non-point sources of nutrients (phosphorus above all) from agricultural land. It is then a typical case study which highlights how agricultural sustainability could be fundamental for environmental safety and, vice versa, how environmental processes (trophic evolution of a lake and related nutrients diffuse sources, in the specific case) could be the focus in the sustainability definition. Being environmental concerns for the Lake Vice rather recent (phosphorus concentration is heavily increased in the last fifteen years) the evolution of land use of last fifty years has been evaluated by the interpretation of aerial photos of 1954, 1971, and 1994. Furthermore, being P mobilisation due to soil erosion, the respective erosion maps have been built up, applying the USLE model at basin scale. This application has been compared with a new approach, based on the integration of GLEAMS (Groundwater Loading Effects of Agricultural Management Systems) results with a GIS (Geographic Information System). Results highlight that the new map, based on GLEAMS, is very similar to USLE map, but it allows a very simple construction of the risk map and, consequently, to immediately plan best management practices (BMP) effectively to control nutrients mobilisation.