Declining water resources in response to global warming and changes in atmospheric circulation patterns over southern Mediterranean France

Abstract. Warming trends are responsible for an observed decrease of water discharge in southern France (northwestern Mediterranean). Ongoing climate change and the likely increase demand threaten availability resources over coming decades. Drought indices like Reconnaissance Index (RDI) increasingly used characterization studies, but little is known about relationships between these indices, resources, overall atmospheric circulation patterns. In this study, we investigate RDI, discharge, four teleconnection patterns (TPs) six coastal river basins France, both historical period last 60 years a worst-case climatic scenario (RCP8.5) reaching year 2100. We combine global regional model (CGM RCM, respectively) outputs with set hydrological data order to past TPs project their potential evolution space time. Results indicate that annual can be reduced by −49 % −88 end century under extreme conditions. Due unequal links TPs, hydroclimatic unevenly distributed within study area. Indeed clustering analysis performed RDI time series detects two major clusters, separating eastern western part region. The former indicates stronger Atlantic (e.g. North Oscillation (NAO) Scandinavian (Scand) patterns), whereas latter more closely related Mediterranean (Mediterranean (MO) Western (WeMO)). future simulations predict antagonistic clusters which driven decreasing Scand WeMO. provokes general tendency lower P during spring, summer, autumn, might partly compensate enhanced precipitation cluster autumn winter. However, compared observations, representation WeMO MO considered models less satisfactory NAO Scand, further improvement therefore requires better representations TPs.