Environmental Flow Scenarios for a Regulated River System: Projecting Catchment‐Wide Ecosystem Benefits and Consequences for Hydroelectric Production

To enable prioritization among measures for ecological restoration, knowing the expected benefits and consequences of implementation is imperative but rarely explicitly quantified. We developed a novel method to prioritize environmental flow rehabilitate ecosystems in Ume River catchment northern Sweden, river system heavily regulated hydropower production. Our strategy was identify with minimal impact on production while providing substantial benefits. Based field surveys remaining natural values potential rehabilitation, we quantified projected gain habitat area implementing flows target organism groups, example, lotic fish species riparian vegetation, along whole length. by identifying set operational rules reflecting constraints added flows. then used optimization software calculate changes revenues. Implementing restrictions zero-flow events mandating minimum discharge at all run-of-river stations allocating 1%–12% mean annual bypassed reaches entire would result 2.1% loss electricity Adding fishways increase 3.1% per year. With more water-level fluctuations impoundments, increases 3.8%. These actions like grayling Thymallus than threefold vegetation about 66%. forms basis ongoing nationwide rehabilitation schemes.