1. Laboratory of Hydraulic Constructions, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland (corresponding author).
2. Laboratory of Hydraulic Constructions, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
3. Professor, Laboratory of Hydraulic Constructions, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.