1. a Laboratory of Hydraulic Constructions (LCH) , Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 , Lausanne , Switzerland E-mail:
2. b Laboratory of Hydraulic Constructions (LCH) , Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 , Lausanne , Switzerland
3. c Laboratory of Hydraulic Constructions (LCH) , Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 , Lausanne , Switzerland E-mail:
4. d formerly Laboratory of Hydraulic Constructions (LCH) , Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 , Lausanne , Switzerland