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