Land Use, Phosphorus Pollution and Risk Assessment for the Bolsena Lake (Italy). An Estimation Using Remote Sensing and Multi Criteria Analysis

This study aims to assess the sustainability of the Land Use (LU) in the water basin of Bolsena Lake (Italy), by measurement of eutrophication status. The total annual phosphorus (P) load was quantified using the simulation model Groundwater Leaching Effects of Agricultural Management Systems (GLEAMS). The Multi-Criteria Analysis (MCA), conducted in accordance to the fuzzy logic, has allowed us to define the Risk Map that shows areas of environmental vulnerability with regards to eutrophication processes. Finally, areas were identified through meta-planning to introduce BMPs (Best Management Practices), that represent a useful tool to reduce nutrients loads, that reach the water body causing eutrophication. The main results obtained show that the total (P) produced in the water basin is 92 tons/year, while four Risk classes were defined according to their vulnerability of the territory to release nutrients. A detailed phytodepuration plan were proposed, that could reduce from 30% to 60% the phosphorus load per year. Both the GLEAMS model and the MCA are found to be essential tools to quantify the factors causing the eutrophication and to identify the most critical areas.