Flash Floods in Alpine Basins

Flash floods are a major natural hazard under different climatic conditions. In the European Alps, flash flood hazard often results in major risk due to the increasing presence of elements at risk (urban areas and transportation routes) in valley floors and on alluvial fans endangered by flash floods. The assessment of the hazards related to flash floods requires collection of reliable quantitative data on these phenomena. Due to the space scale of flash flood occurrence, which mostly occur in ungauged catchments, hydrometeorological data from monitoring network need to be integrated by data collected by means of post-flood surveys. This paper presents methods for flash flood data collection and discusses the basic characteristics of flash floods in alpine catchments based on the analysis of a sample of 6 flash floods (20 catchments), which occurred from 1999 to 2006 in Italy, Austria and Slovenia.