1. Department of Civil Engineering; University of Bristol; Bristol UK
2. Now at Department of Environmental Systems Science; ETH Zurich; Zürich Switzerland
3. School of Earth and Environmental Sciences; University of Queensland; Brisbane Qld Australia
4. Institute of Earth Surface Dynamics; University of Lausanne; Lausanne Switzerland
5. Water Resources Section, Faculty of Civil Engineering and Geosciences; Delft University of Technology; Delft The Netherlands