1. Department of Geotechnical Engineering and Geoscience; Technical University of Catalonia-UPC; Gran Capitan s.n. 08034 Barcelona Spain
2. Universidad Politécnica de Madrid; Ríos Rosas 21 28003 Madrid Spain
3. Geosciences Rennes UMR 6118 CNRS; Université de Rennes I; 35000 Rennes France
4. International Hydrological Programme UNESCO; Division of Water Sciences; 1, rue Miollis - 75732 Paris Cedex 15 France