GROUNDWATER RESOURCES FROM CARBONATE ROCKS IN MOUNTAINOUS REGIONS: HYDROCHEMICAL AND ISOTOPIC SURVEY OF GROUNDWATERS IN THE WESTERN PYRENEES (FRANCE)

摘要

Carbonate rock aquifers are one of the main water supply sources for the French Western Pyrenees. The discontinuous structure of these reservoirs is a main obstacle to the development of such resources. By the way, since no other aquifer can be tapped, many communities have decided to improve their knowledge of the main springs over the whole region. Four sites have been considered from 2003 to 2006 and have been the object of multidisciplinary investigations including: geological mapping, geophysical investigations, dye tracing experiments and in situ hydrochemical survey. Stable isotopes have been analysed on both rainfall ( 18O, 2H) and spring waters ( 18O, 2H, 13C, 34S) in order to evaluate the origin of groundwaters, their residence time within the systems and to appreciate the occurrence of exchanges with other aquifers. Finally, this study provides a good example of how to include hydrogeochemistry and isotopic tools in a water supply management policy.