1. Senior Lecturer, UNESCO-IHE Institute for Water Education, P.O. Box 3015, 2601 DA Delft, The Netherlands.Director, HydroLogic BV, P.O. Box 2177, 3800 CD Amersfoort, The Netherlands.
2. Research Fellow, McMaster Univ., Dept. of Civil Engineering, 1280 Main St. West, Hamilton, Ontario, L8S 4L7 Canada.
3. Associate Professor, UNESCO-IHE Institute for Water Education, P.O. Box 3015, 2601 DA Delft, The Netherlands. (corresponding author).