1. Institute of Earth Sciences Univ. of Lausanne Lausanne Switzerland
2. Dep. of Soil and Environment Swedish Univ. of Agricultural Sciences Uppsala Sweden
3. Dep. of Agroecology and Environment Agroscope Zürich Switzerland
4. Soil and Terrestrial Environmental Physics, Dep. of Environmental Systems Science ETH Zürich Switzerland
5. Division of Hydrologic Sciences Desert Research Institute Reno NV 89512 USA