Institute of Water and Environment, Department of Hydrology and River Basin Management, Technische Universität München, Arcisstrasse 21, 80330 Munich, Germany

Department of Water Management, Faculty of Civil Engineering, Delft University of Technology, P.O. Box 5048, 2600 GA Delft, The Netherlands

University of Illinois at Urbana-Champaign, Departments of Geography and Civil and Environmental Engineering, 220 Davenport Hall, 607 South Mathews Avenue, Urbana, IL 61801, USA