1. Research Fellow, Fonds National de la Recherche Scientifique and Univ. catholique de Louvain, Dept. of Civil Engineering, Hydraulics Unit, Place du Levant, 1, B-1348 Louvain-la-Neuve, Belgium.
2. Professor, Dept. of Civil Engineering, Hydraulics Unit, Univ. catholique de Louvain, Place du Levant, 1, B-1348 Louvain-la-Neuve, Belgium.