A geographic information system (GIS) with integrated models: a new approach for assessing the vulnerability and risk of desertification in Sardinia (Italy)

Land degradation assessment is a priority when making decisions for environmental protection, particularly so in the Mediterranean area. Among the various approaches adopted to monitor degradation processes and to formulate mitigation action plans, a model-based methodology would appear to be the most effective, because it synergically combines the indicators central to the DPSIR (Driving Forces, Pressure, State, Impact, Response) framework. The approach hereby presented has been applied to evaluate the vulnerability and risk of desertification in Sardinia (Italy). Assuming that desertification is the result of predisposing (geographic), triggering (climatic) and quickening (human impact) factors, a new methodology has been developed which combines, within an integrated model framework, a wide range of desertification indicators which have already been developed by various projects focusing on the Mediterranean area. The modelling procedure was applied to two different time periods (determined by the availability of data): the early 1990s and the present. Data have been compiled and rearranged in a geographic information system (GIS) context, thus facilitating input for the various models applied. This allowed us to highlight both the spatial and the temporal variabilities in the desertification phenomenon, and to estimate the susceptibility of land with regard to each of the degradation processes. The temporal variability was determined by past trends, and future simulations of land use, and climate change.