1. Division of Hydrologic Sciences; Desert Research Institute; Las Vegas NV 89119 USA
2. Institute of Terrestrial Ecosystems; ETH Zurich; Universitätstrasse 16 CH-8092 Zurich Switzerland
3. Dipartimento di Ingegneria Civile e Ingegneria Informatica; Università degli Studi di Roma Tor Vergata; 00133 Rome Italy
4. Institute for Geotechnical Engineering; ETH Zurich, ETH Hönggerberg; CH-8093 Zurich Switzerland
5. CSIRO Land and Water; GPO Box 1666 Canberra ACT 2601 Australia