Mediterranean extreme floods and flash floods

The Mediterranean area is particularly exposed to flash floods. Floods are weather-related hazards and their patterns are likely to be significantly affected by climate change. Floods are already the most frequent and among the costliest and deadliest natural disasters worldwide (Munich RE, NatCat Service; Swiss RE, 2015). This is also true in the Mediterranean area. The EMDAT international disaster database (http://www.emdat.be/) lists for instance 200 billion Euros damages related to various disasters since 1900 in the countries surrounding the Mediterranean Sea, out of which 85 billion are related to river flooding. Disastrous flash-floods1 are much more frequent in some parts of the Mediterranean region than in the rest of Europe (Gaume et al. 2009; Llassat et al. 2010). This is due to the local climate, which is prone to short intense bursts of rainfall. The reliefs surrounding the Mediterranean Sea force the convergence of low-level atmospheric flows and the uplift of warm wet air masses that drift from the Mediterranean Sea to the coasts, thereby creating active convection. In addition, population growth is particularly high along the Mediterranean coasts, leading to a rapid increase in urban settlements and populations exposed to flooding.