National Atlas of areas at risk of desertification — Impact Index: thin soils on steep slopes

The Ministry of the Environment and the Protection of the Territory financed by act of 28-12-2001 the Experimental Institute for the Study and Defense of Soil for the preparation of National Atlas of areas at risk of desertification at the scale of recognition (reference scales 1:100,000-1.250,000). The MATTM considers this Atlas as a preparatory instrument for the correct implementation of the National Plan for Combating Siccity and Desertification, adopted by the Italian State in implementation of the United Nations Convention on Combating Siccity and Desertification. The above-mentioned act provides for the participation of the National Institute of Agricultural Economics in its specific areas of competence. The study area includes Abruzzo, Basilicata, Calabria, Campania, Lazio, Marche, Molise Puglia, Sardinia, Sicily, Tuscany, Umbria. The thin soil impact index on steep slopes identifies areas where soils are vulnerable to water derosion processes. Areas with a slope of more than 15 % and without soil information are classified as missing data. All other areas are classified not at risk. The information layer was obtained by overlapping the two status indicators: thin soils and steep slopes. Indicator of thin soil status: thickness is a characteristic of the soil on which derosion processes act directly, i.e. it determines the potential evolution towards a state of functional sterility. Soils considered potentially vulnerable are those with rootable depth less than 50 cm. A territorial component has been considered as potentially vulnerable when at least 40 % of the soils describing it are vulnerable. High slope status indicator: slope is an important factor for the triggering and dynamics of water derosion processes. Steep slopes were considered to be higher by 15 %.