Control of sediment transport on an alpine catchment basin for the safe application of smart storage operations on an run-off-river HPP

Smart storage operations (SSO) have been implemented on an alpine run-off-river HPP (case study: KW Gletsch-Oberwald HPP) in order to enhance the flexibility of the power plant (ref poster SmallFlex). SSO operations consist on the use of available space underground, such as the settling basin, in order to store the water, particularly in periods of the year with low inflow, which can afterward be used for energy production when the demand and the remuneration tariffs are higher and at a discharge close to the optimum of the turbine to have the best efficiencies. The aim of efficiently implementing the SSO operations on the settling basin requires sediment management in order to assure a safe use of this part of the system whose function is temporarily changed. In order to understand the amount of sediment inflow into the settling basin, the following actions were undertaken: Determine the amount of potential mobilized sediments at the catchment scale with the use of Beyer-Portner (1998) and Gavrilović (1990) formulas; • Determine the maximum sediment transport capacity of the river Rhone upstream the intake with the use of Beyer-Portner (1998) formula. This will allow to verify in which periods of the year the sediment basin can be used for water storage with no risk related with sediment conveyance into the waterways and therefore at the turbines.