Author(s): Sahra Naima Sabil; Keilly Bulle Arias; Tor Haakon Bakken; Knut Alfredsen

Linked Author(s): Tor Haakon Bakken, Knut Alfredsen

Keywords: 10-year floods; Climate change; Hydropower reservoirs; Flood dampening

Abstract: The flood peak dampening due to hydropower reservoirs in the Surna river basin in Norway was studied by simulating unregulated floods with an HBV model and routing them through a Level-Pool Reservoir Routing python script. Four scenarios with future runoff data and spatial and temporal runoff variations were simulated to investigate limiting factors of flood dampening and environmental impacts by looking at flood-reoccurrence intervals. The study found that the reservoirs had a peak reduction of 50-96% under median reservoir filling levels. The minimum pre-release period to prevent spilling amounts 5.3-35.8 days. Limiting factors for flood peak reduction are reservoir storage capacities, transfer intake capacities within the basin, regulation rate of the basin, and hydrograph shapes. To target an outflow corresponding to a 10-year flood (Q10) during the flood event, additional discharge regulation is necessary, involving either increasing the outflow by up to 210 m³/s or reducing it by up to 51 m³/s.

DOI: https://doi.org/10.64697/iahr.proc.ise2026.abs.194

Year: 2026