Hydraulic classification of hydropeaking stages in a river reach

Abstract

AbstractHydropower is an important tool in the struggle for low‐emission power production. In the Nordic countries, hydropower operating conditions are expected to change and work more in conjunction with intermittent power production. This in turn might increase the amount of hydropeaking events in the reaches downstream of hydropower plants. The current work investigates the influence of highly flexible, high‐frequency hydropeaking on the hydrodynamics in the downstream reach. By quantifying four different dynamic stages in the study reach, the influence of the hydropeaking frequencies was investigated in the bypass reach of the Stornorrfors hydropower plant in the river Umeälven in northern Sweden. The hydrodynamics in the study reach were numerically modelled using the open source solver Delft3D. Eight different highly flexible future hydropeaking scenarios, varying from 12 to 60 flow changes per day, were considered. A method for identifying four hydropeaking stages—dewatering, dynamic, alternating and uniform —was introduced. The hydropeaking frequency directly decided the stage in most of the study reach. Furthermore, a Fourier analysis showed a significant difference between the stages and their corresponding power spectra. The classification of stages put forward in this work provides a novel, simple method to investigate the hydrodynamics due to hydropeaking in a river reach.