Floods evolution in the Mediterranean region in a context of climate and environmental change.

Abstract

Floods are the most important risk in the Mediterranean region, both due to their frequency and impact. Studies of historical floods show flood-rich periods that could be associated with climate causes, but there is also a certain growing trend as a result of changes in land use and increased vulnerability. If climate scenarios point to an increase in the torrentiality of precipitation, with longer dry periods and more intense rainfall, there is still a high level of uncertainty in their impact in floods. This paper addresses this issue, also considering the complex role of changes to hazards, vulnerability, exposure and capacity. It presents a synthesis of the state of the art, with particular incidence in the first results of MedECC and the most recent bibliography on floods trend. Conclusions show that floods in this region are mainly consequence of flash-flood events. A common positive trend of flash floods in the past probably due to land use changes and the occupation of flood-prone areas has been found (high confidence). The increase of convective precipitation could also justify this positive trend in the most recent period, in some regions (low confidence). Vulnerabilities to water related hazards are expected to be influenced by the future socio-economic conditions at the regional scale (medium confidence). Although expected changes in flood risks are not univocal, nor evenly distributed, flood impacts will increase in the entire Mediterranean region, mainly as a consequence of global changes in the catchments (land use, vulnerability, exposure), joined in the Northern part of the basin to the increase of heavy rainfalls (medium confidence).