1. Dep. of Earth SciencesUtrecht Univ.Budapestlaan 4, P.O. Box 800213508 TAUtrechtthe Netherlands
2. Soil and Groundwater SystemsDeltares, Princetonlaan 63584 CBUtrechtthe Netherlands
3. Dep. of Mechanical EngineeringEindhoven Univ. of TechnologyP.O. Box 5135600 MBEindhoventhe Netherlands
4. Kleiststrasse 1970197StuttgartGermany
5. Dep. of Hydromechanics and Modelling of HydrosystemsStuttgart Univ.Pfaffenwaldring 6170569StuttgartGermany