Flood hazard of the Somma-Vesuvius region based on historical (19-20th century) and geomorphological data

Abstract

This paper presents a preliminary susceptibility map of the flood hazard for the Somma-Vesuvius volcanic district, worked out by means of multidisciplinary historical, geological, geomorphological and rainfall data processing. It is well known that the Somma-Vesuvius volcano, due to its explosive volcanism and the dense urbanization of the surrounding area, with a population exceeding 650,000 is one of the most dangerous active volcanoes of the world. Although this area has been extensively studied from the volcanological point of view with regards to its volcanic hazard, there are currently not many detailed studies about its flood hazard factors, despite the fact that, in the last century, many intense rainfall events in this area have produced several floods that invaded the surrounding plains affecting towns and roads, and causing much damages and loss of lives. Accordingly, in this paper high-resolution DEM (5×5 m pixel) and detailed geomorphological maps of the whole area have been analyzed and processed in GIS environment, carrying out a comparative study of the present-day morphology and the morphology of the 1900’s volcanic edifice, including changes of infrastructures and buildings throughout the last century. These results, together with historical chronicles data and the rainfall accurate data for all flood events, have been processed in this paper for highlighting the drainage basins areas of Somma-Vesuvius where the flood phenomena could be more probable in the future, working out a preliminary zoning map, also suggesting in which sectors interventions useful for mitigation of flood risk should be implemented.