Lavey Dam - Physical and numerical analysis of flow and sediment transport in the Rhone River

As several of other run-of:river hydropower plants, the hydraulic scheme of Lavey on the Rhone River in Switzerland is concerned by continuous reservoir sedimentation. To determine the flood evacuation capacity of the weir as well as the flow distribution between the four entries of the water intake with and without bed load, a 1 :40 physical scale mode was used. Water levels, flow pattern, flow distribution, sediment deposition and flushing are measured continuously by non-intrusive equipment. Hydraulic tests show that the central dam gate is the most loaded and reveal the importance of three-dimensional phenomena in the curved river reach. The discharge is distributed homogeneously between the four openings of the intake. The test series with bed load allow reproducing the processes of sediment transport in the Rhone River as well as the deposits measured in situ before a flushing event. The prototype behaviour validates the results of physical modelling, including flushing operation. The applied three-dimensional numerical model (FLOW3D (R)) is a powerful complementary tool for generating approach flow pattern and for pre-evaluation and comparison of design alternatives.