Sensibilité aux mouvements de masse dans l'Apennin méridional (Campanie, Italie). Exemple des bassins versants de l'Ufita, du Miscano et du Calaggio

Abstract

This work studies the relationship between the sensibility of slopes to mass movement and different factors, including rainfall regime, in a part of the Southern Apennines characterized by a high litho-structural complexity.Rainfall regime has been defined from a series of long-term data, which have made it possible to calculate a number of climatic levels. Here are presented those that are of particular importance in triggering and development of erosion phenomena.Using GIS technology, we have developed a map of sensibility to mass movements, which associates different information layers. This map is constructed through other intermediate maps (map of the physiographic units, map of the territorial systems), but it superimposes the location of the mass movements (mud flows, debris flows, landslides, rock-falls) listed in the IFFI database which includes all known events, recent or attested by historical archives.Of the 122 events precisely dated of the AVI database (1941-2000), 21 occurred in November 1980 and 37 in January 1997. The first are the consequence of the strong earthquake that struck Southern Italy on November 23, 1980. The others correspond to abundant but no exceptional monthly rainfall in the Miscano basin, reflecting the inadequacy of the monthly values to define the rainfall aggressiveness.The data and maps obtained emphasize the importance of lithology and relief of the survey in the spatial distribution of mass movements. Rainfall is not a really discriminating factor on the study area. The events of instability are particularly numerous on the clayey and marly slopes steeply inclined. On the contrary, they are rare on the very slightly inclined slopes of the downstream part of the Ufita and Calaggio basins.

Keywords

• mass movements
• Italy
• climatic indices
• rainfall aggressiveness
• physiographic units
• SIG