1. USDA-ARS, US Salinity Lab.; 450 W. Big Springs Rd. Riverside CA 92507-4617
2. National Institute for Public Health and the Environment (RIVM); Dep. of Statistics, Informatics and Modelling; PO Box 1 3720 BA Bilthoven the Netherlands
3. Utrecht Univ.; Faculty of Geosciences, Dep. of Earth Sciences; Utrecht the Netherlands
4. Dep. of Land, Air and Water Resources; Univ. of California; One Shields Ave. Davis CA 95616