1. KWR Water Cycle Research Institute; PO Box 1072 3430 BB Nieuwegein The Netherlands
2. Environmental Sciences, Soil Physics, Ecohydrology and Groundwater Management Group; Wageningen UR; PO Box 47 6700 AA Wageningen The Netherlands
3. Department of Systems Ecology; VU University, Institute of Ecological Science; de Boelelaan 1085 1081 HV Amsterdam The Netherlands