Sedimentmanagement KW Feistritz - Activating Sediment Transport Downstream of Run-of-River Stations

Sediments removed by reservoir flushing above run-of-river stations tend to settle immediately downstream of the dam. Sediment remaining near the turbine outlets raises the water level and thus reduces the head available for power generation. In addition, this interrupts the natural process of sediment transport, making it difficult to accomplish a good ecological status as defined in the EU Water Framework Directive. This research project is a sequal to the accomplished project Optimising Sediment Transport Downstream of Run-of-River Stations in which the extension of the downstream pier between the spillway and turbine bay was examined. This investigation yielded valuable information for the future construction of run-of-river stations. As the hot plug-in of such a pier is very expensive this research project aims at investigating the installation of groins instead. Groins are inexpensive and improve the ecological quality by diversifying the flow pattern. As a first step a scaled model test for a particular run-of-river station will be carried out to optimize shape, disposition and height of the groins with respect to their capacity of sediment transport. As a second step a 3D numerical model is developed. Data from the model test is used to calibrate the numerical model. The gained insights and the numerical 3D-model shall be generalized for other run-of-river stations.