Western Pyrenees facing global change: comparison of the effects of climatic and anthropogenic change on water abstractions

In the French Western Pyrenees, the trend to the decrease of low water flows that has been observed during the current years should be going on in the future. This may increase the hydric stress on aquatic ecosystems, and the competition among water uses and users for accessing water resources.

The research project ANR-VULCAIN compared the impacts of climatic and socio-economic change on the hydro­systems of the French Western Pyrenees. Modeling and participative prospect analysis have been coupled to quantify the evolution of water abstractions under these two types of change. Socio-economic scenarios have been built together with local stakeholders during workshops (urbanism / land planning on the one hand and agriculture on the other hand). Their results have been quantified with the models developed so as to assess anthropogenic change impacts on domestic and agricultural abstractions. In parallel, the agricultural model has been fed with climatic scenarios so as to assess the impacts of climate change on agricultural water needs.

In the created scenarios, the evolution of agricultural water needs under climate change have a bigger range than the evolution of abstractions for domestic water and agricultural needs under anthropic change, which are the same order of magnitude. To satisfy this evolution, there are some rooms to maneuver: make distribution modalities more efficient, optimize the management of storage capacity, or use substitution resources.
This paper presents the approach that has been followed, and some of the main results.