13ème Congrès Mondial de l'Eau, Montpellier, France

OS3c Climate change: detecting trends, projecting future

abstract 634

Impacts of climate change on the water resources of coastal Mediterranean rivers in southern France

Author(s): Franck Lespinas, Wolfgang Ludwig, Serge Heussner
CEFREM - Centre de Formation et de Recherche sur l’Environnement Marin (UMR5110-CNRS/Université de Perpignan), Université de Perpignan, 52, avenue Paul Alduy, 66860 Perpignan, Cedex, France. Tel: +33-46866-1746. Fax: +33-46866- 2096. E-mail address: franck.lespinas@univ-perp.fr

Keyword(s): Climate change, Hydrology, Coastal rivers, Mediterranean.

Article:

Poster:

Session: OS3c Climate change: detecting trends, projecting future

AbstractIntroduction

Recent climate monitoring

and modelling studies revealed a general trend toward drier and warmer conditions in the Mediterranean area, both

for the last and forthcoming centuries. Such a climatic evolution would lead to a decrease of water resources likely

affecting ecosystems, socio-economic activities and populations. In this study, we aimed to analyse recent and future

climate change and its consequences on the water resources of 6 coastal Mediterranean rivers located in southern

France.

Objectives

1. Examine the major climatic conditions changes for the period 1965

-2004 and its consequences on the water resources in the considered watersheds.

2. Build scenarios on

the evolution of the water resources in the 6 considered rivers for the end of the 21st century.

Methods

Firstly, we collected a comprehensive dataset of hydrometeorological data from climatic

and hydrologic stations for the period 1965-2004. A digital elevation model was used to delineate the 15

watersheds according to the geographical position of the considered hydrologic stations. Climatic parameters were

spatialised and averaged for each watershed. All reconstituted hydroclimatic data time-series were tested in order to

detect significant trends over the study period and the consequences of the changing climatic conditions on the

hydrologic variables were examined through correlation analysis and hydrological modelling.
Secondly, the

climatic change scenarios for the period 2070-2099 produced by the PRUDENCE project were coupled with the

GR2M hydrologic model calibrated for the present conditions. This allowed us to provide a first estimation of the

possible changes in the water resources that could occur in the studied rivers at the end of the 21st

century.

Results

1965-2004 was characterised by a temperature increase of about 1.5°C, mainly

because of a strong warming during spring and summer. Precipitation did not follow significant changes, except a

small decrease in winter in the northernmost watersheds. Water discharge significantly decreased in one third of the

watersheds, accounting for an overall decrease of the water resources in this area of about 20%. Increasing losses

by evaporation processes due to the temperature increase are likely to be responsible for this.
First results of the

coupling of climatic and hydrologic models revealed a decrease of the water resources between 20 and 70% for the

end of the 21st century, depending on the considered rivers and both the scenarios and climatic models we used.

Conclusion

Although precipitation in the studied watersheds did not change markedly during 1965

-2004, our results already revealed a significant decrease in the water resources, likely related to the strong

temperature increase. According to model scenarios, this temperature increase will also be accompanied by

decreasing precipitations and hence still extend the decline of the water resources in the future.

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Impacts of climate change on the water resources of coastal Mediterranean rivers in southern France