Watershed monitoring and modelling: Remote sensing and GIS applications in the Mediterranean environment

GIS and remote sensing were employed in an application of the SEMMED model to environmental planning in two Sicilian watersheds, the Simeto and Timeto Basins. The model performed well but weaknesses emerged. Validation was hampered by a lack of watershed erosion data In two, 46 km(2), sub-watersheds of the Simeto, the Nicoletti and Ancipa, one located in the central hilly area, the other close to the northern mountains, measurements of sediment accumulation in reservoirs suggest soil loss rates of 7.4 and 4.7 t/ha/yr. However, the SEMMED-estimated values were 3.56 and 2.78 t/ha/yr. - a major underestimation. There is a need for more detailed soil data and a re-examination of vegetation cover inputs.