Flood hazard analysis in the Oliveto River Basin (Southern Italy)

Abstract

Generally, a flood is a temporary flooding of areas that usually are not covered with water. The main driving factors are heavy rainfall, bridge obstructions, dam break, land use change, anthropogenic pressure etc. In many cases, individual driving factors are analyzed without an integrated analysis of all the main driving factors. The paper describes a case study on the flood hazard assessment in the Oliveto River basin through a multi-hazard analysis. In this analysis geomorphological, sedimentological, climatic, hydrological, and hydraulic aspects, together with the identification of criticalities that can increase the hydraulic hazard, were analyzed to identify areas subject to potential flooding. The paper mainly highlighted that a flood hazard analysis, carried out by considering only a single driving factor, can underestimate the hazard. Furthermore, the paper shows how that the analyses on a local scale and not on a basin scale can lead to partial or misleading results. Indeed, the analysis highlighted the possibility of hazard conditions just for non-exceptional events, characterized by a 50-year return period, in absence of dam break and sediment transport. The hazard conditions increase due to the openings in the levees near man-made areas and it can be further increased if a dam break occurs or if the discharge is not only water but also includes sediments and blocks.