Hydropeaking mitigation measures in the Swiss Upper-Rhône basin

Hydropower operations can cause hydropeaking particularly in the case of pumped storage systems located in mountainous regions. Due to the rapidly varying discharge conditions, hydropeaking leads to several problems such as stranding of fishes and invertebrates or drying out of spawning zones. This research project considers a case study including five hydropower plants located in the Upper-Rhone Basin where two river reaches were found to be affected by hydropeaking. A panoply of concepts was conceived and evaluated based on financial, feasibility, and production criteria. A combination of both structural and operational measures is proposed to eliminate or at least highly reduce hydropeaking in the affected river reaches. A challenging aspect of the study was the limited availability of data in the river reaches and the fact that the main assessment relied on the measured turbined discharges.