ABSTRACT
Generation companies of hydropower plants often are in difficulties to realize an ecological as well as economic sediment management of their reservoirs. Because the most common methods (reservoir flushing and machine excavations) do not meet these requirements, the Vorarlberger Illwerke AG has developed a system that achieves both the environmental and economic requirements. The plan is to lift the sediments in one of the reservoirs by suction excavator and to add them to a head race tunnel which leads the sediments into the original riverbed. Thereby the sediment discharge is not constant. It depends on the simultaneously measured stream flow conditions (discharge and amount of suspended load) of the diverted waters which is due to the existence of reservoirs low in suspended load. This ensures a sustainable return of sediments into the river and that the suspended load concentrations are similar to an undisturbed natural river.
