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Vulnerability of Mediterranean hydrosystems to climate changes and human activities: the VULCAIN project

Author(s): Assessing spatial and temporal mean variability of likely future precipitation and temperature modifications for the 2020-2040 and 2040-60 periods over a Mediterranean basin
IWRA World Water Congress 2008 Montpellier France
3. Climate Change and Disasters
Author(s): Yvan Caballero
Luc Neppel
Bernard Ladouche
Jean-Louis Pinault
David Salas
Melia Salas
Eric Martin
Nathalie Dorfliger
Jean-Daniel Rinaudo
Jean-Michel Citeau
Sébastien Chazot
Laure Maton
Keltoum Chaouche Yvan Caballero(1)(*), Luc Neppel (3), Bernard Ladouche (1), Jean-Louis Pinault (2), David Salas y Melia (5), Eric Martin (5), Nathalie Dorfliger (1), Jean-Daniel Rinaudo (1), Jean-Michel Citeau (4), Sébastien Chazot(4), Laure Maton (1), Keltoum Chaouche (3), Isabelle Terrasson (4), Perrine Fleury (1) (*) corresponding author (1) BRGM - Unité EAU-RMD. Service Géologique Régional Languedoc – Roussillon. 1039, rue de Pinville. 34000 Montpellier. (2) BRGM – Unité EAU-M2H. Centre Scientifique et Technique. B.P. 6009. 45060 Orléans Cedex 02. (3) HydroSciences Montpellier – HSM. Maison des Sciences de l’Eau, Université Montpellier II. Place Eugène Bataillon. 34095 Montpellier Cedex 5. (4) BRL ingénierie. 1105, Avenue Pierre Mendès France. BP 4001. 30001 Nîmes Cedex. (5) Groupe d’étude de l’atmosphère météorologique. CNRM-GAME (Météo-France, CNRS). 42 Avenue de Coriolis. 31057 Toulouse.

Keyword(s): Climate change, GCM, downscaling, observed trends, climate scenarios, hydrological and hydrogeological modelling, Mediterranean

AbstractThe Mediterranean region, that includes interconnected hydro-systems in which groundwater is important, is subjected to a contrasted climate and an increasing anthropogenic pressure. Global warming over Mediterranean region will probably cause more warm and dry summers and more precipitation during warmer winters despite shorter rainy seasons. Those changes are likely to exaggerate considerably the range in flows between winter and summer. They will also complicate the water management strategies mainly oriented to respond to the domestic and agricultural water demand. In the Languedoc-Roussillon region for instance, the population growth (on a mean range of 1,5% per year) is likely to provoke a substantial increase of the water demand by a rate close to 20% in the next 15 years, when alternatively, irrigation systems size should slightly decrease in the future. In addition, environment-protection policies will be enhanced in the future with the implementation of the European Water Framework directive. Within this general framework, the VULCAIN project aims for the implementation of an integrated (transdisciplinary) modelling method to assess the climatic and socio-economic driving forces impacts over the Mediterranean hydro-systems at mean (2020-2040) and longer- term (2040- 2060). The study zone is the Pyrénées Orientales département, chosen because it contains on the one hand, specific Mediterranean hydro-systems (coastal multi-layer aquifer, karstic systems with endogenous and exogenous recharge by rainfall and water losses and three river basins controlled by dams), and on the other hand, a socio- economic context that is close to the most critical of the Languedoc-Roussillon region in terms of water demand and available water resources. This paper presents the first-year results of the VULCAIN project. Climate scenarios were built both from the simulation results of six global circulation models (GCM) (four of which involved in the IPCC-AR4 project) under the A2 greenhouse gases emission scenario of the IPCC and from trends provided by stationarity analysis on the observed rainfall and temperature chronics during past 50 years. A precipitation and temperature stochastic generator was used to the downscaling and for the observed trend extrapolation. A baseline scenario was developed, describing the expected evolution of economic activities depending on the water resources and on socio-economic and political drivers of the study area. Assuming that climate does not change, this scenario was built to be consistent with assumptions underlying the definition of the SRES scenarios at a global level. Together with the climate scenarios, it will be used to force hydrological/hydrogeological models developed in previous studies. Early results of the integration between water use and management (linked to the socio-economic context) and hydrological/hydrogéological models are presented. Aiming to develop integrated tools and methods to the operational assessment of the global change impacts, they will allow evaluating the future vulnerability of the exploited hydro-systems and of the supplied territory in the Mediterranean context.
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