Adapting the operation of two cascaded reservoirs for ecological flow requirement of a de-watered river channel due to diversion-type hydropower stations

► An innovative method is proposed to adapt reservoir operation for fish habitat. ► An optimization model is developed that allows for an objective trade-off between hydropower production and ecological requirements. ► A case study shows the model's potential for defining eco-friendly reservoir operation. ► Extensions towards cases with more than one target species are straightforward.