A 1400-years flood frequency reconstruction for the Basque country (N Spain): Integrating geological, historical and instrumental datasets

We present the first reconstruction of past flood events variability in Basque Country and Western Ebro Basin (Northern Spain) integrating instrumental hydrological datasets (last 20 years), documentary archives 700 years) Lake Arreo (655 m a.s.l.) sedimentary paleoflood record 1400 years). In this lake, allochthonous coarse fine detrital layers (CDL FDL respectively) intercalated within endogenic laminites were identified interpreted as high- moderate-energy events. The interplay between human activities hydroclimate has controlled deposition these layers. Gauged data for last years suggest that floods are typically generated by heavy rainfall on saturated soils after several days continuous rainfall. These occur mostly during cold season (Oct–May). reconstructed frequency high-magnitude from lake is coherent with historical cold-season rivers. lowest took place 6–7th 10–15th centuries, while higher occurred 8–9th centuries 500 years. Fluvial lacustrine records evidence show abrupt large increases extreme termination Little Ice Age (1830–1870 CE) mid to late 20th century, both periods Rapid Climate Change (RCC). significant increase observed RCC suggests a similar pattern could be expected near future ongoing global warming.