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

[摘要] Warming trends are responsible for an observed decreaseof water discharge in southern France (northwestern Mediterranean). Ongoingclimate change and the likely increase of water demand threaten theavailability of water resources over the coming decades. Drought indiceslike the Reconnaissance Drought Index (RDI) are increasingly used in climatecharacterization studies, but little is known about the relationshipsbetween these indices, water resources, and the overall atmosphericcirculation patterns. In this study, we investigate the relationshipsbetween the RDI, water discharge, and four atmosphericteleconnection patterns (TPs) for six coastal river basins in southernFrance, both for the historical period of the last 60 years and for aworst-case climatic scenario (RCP8.5) reaching the year 2100. We combineglobal and regional climate model (CGM and RCM, respectively) outputs with aset of observed climatic and hydrological data in order to investigate thepast relationships between the RDI, water discharge, and TPs and to project theirpotential evolution in space and time. Results indicate that annual waterdischarge can be reduced by − 49 % to − 88 % by the end of the century under theextreme climate scenario conditions. Due to unequal links with TPs, thehydroclimatic evolution is unevenly distributed within the study area.Indeed a clustering analysis performed with the RDI time series detects twomajor climate clusters, separating the eastern and western part of the studyregion. The former indicates stronger relationships with the Atlantic TPs(e.g. the North Atlantic Oscillation (NAO) and theScandinavian Oscillation (Scand) patterns), whereas the latter is more closelyrelated to the Mediterranean TPs (Mediterranean Oscillation (MO) and Western Mediterranean Oscillation (WeMO)). The future climatesimulations predict an antagonistic evolution in both clusters which arelikely driven by decreasing trends of Scand and WeMO. The former provokes ageneral tendency of lower P in both clusters during spring, summer, andautumn, whereas the latter might partly compensate for this evolution byenhanced precipitation in the eastern cluster during autumn and winter.However, compared to observations, representation of the Mediterranean TPsWeMO and MO in the considered climate models is less satisfactory comparedto the Atlantic TPs NAO and Scand, and further improvement of the modelsimulations therefore requires better representations of the MediterraneanTPs.

[学科分类] 妇产科学