Floods in the Pyrenees: a global view through a regional database

Abstract

This paper shows the first systematic dataset of flood episodes referring to the entire Pyrenees massif, named PIRAGUA_flood, which covers the period 1981–2015 (available at http://hdl.handle.net/10261/270351, last access: 21 July 2024). First, the structure of the database is detailed so that it can be reproduced anywhere else in the world, adapting to the specific nature of each situation. Subsequently, the paper addresses the spatial and temporal distribution of flood episodes and events (including trends) that affected the Pyrenees regions of Spain (Catalonia, Aragon, Navarre, the Basque Country), France (Nouvelle-Aquitaine, Occitanie) and Andorra, as well as the massif as a whole, for a given period of time. In the case of the Spanish regions, it was also possible to analyse the compensation payments by the Spanish Insurance Compensation Consortium and the number of deceased. The weather types associated with flood episodes were also classified based on sea level pressure and 500 hPa geopotential height from ERA5. The results show 181 flood events and 154 fatalities, some of which affected more than one region. In the Spanish part of the Pyrenees, between 1996 and 2015, there was a total compensation payout amounting to EUR 142.5 million (2015). The eastern part of the area records more flood events than the western one, with Catalonia being the community that registered the highest number of events, followed by Andorra and Occitanie. Associated weather types are dominated by the southern component flow over the Pyrenees region, with a talweg on the Iberian Peninsula and a depression in the vicinity, either in the Atlantic or in the Mediterranean. In terms of the entire massif, there is a slight positive trend of 0.84 events per decade, driven by the evolution of ordinary and extraordinary floods but not significant at 95 %. At a regional level, flood behaviour is more heterogeneous, although not significant for the most part. Nouvelle-Aquitaine is the only region that shows a positive and significant trend of 0.34 events per decade.