Widén Åsa, Renöfält Birgitta Malm, Jansson Roland
Department of Ecology and Environmental Science, Umeå University, 901 87 Umeå, Sweden.
Sci Total Environ. 2024 Dec 10;955:176622. doi: 10.1016/j.scitotenv.2024.176622. Epub 2024 Oct 9.
Hydropower is central to renewable electricity systems, but degrades ecosystems, calling for environmental flow schemes to enhance the ecological status of river systems. Environmental flow assessments need to account for climate change, since climate-driven changes in runoff affect both hydropower operation and riverine ecosystems. Here, we quantify expected changes in hydropower production and environmental benefits of introducing environmental flows in a large regulated river system in northern Sweden in a future climate. Compared with the hydrology of 1981-2010, runoff is projected to increase with climatic conditions projected for 2040, leading to a 2.2 % increase in hydropower production with present rules for turbine and reservoir operation. Implementing environmental flows will result in lower hydropower production losses in with the 2040 climate than at present: Introducing restrictions against zero flow events, discharge to technical fishways and bypassed reaches throughout the year (with seasonal flow variation), as well as having more natural water-level variation in all run-of-river impoundments, would reduce annual hydropower production with 3.5 % with present conditions, and by 3.3 % in 2040. At the same time, the net effect of higher runoff and introducing environmental flows means that the annual hydropower production in the 2040 climate would be only 0.8 % lower compared to 1981-2010. In all scenarios, reservoir filling degree in 2040 was projected to increase compared to scenarios for 1981-2010, and flow requirements were met for both environmental flows and hydropower production over an 83-year scenario-based time series. This study demonstrates the feasibility of introducing environmental flow actions in Sweden, and other regions where increases in runoff are projected, with sustained hydropower production, having large benefits for riverine biodiversity and enhancing resilience of riverine ecosystems to climate change. For this to be successful, collaboration among stakeholders in riverine management is needed.
水电是可再生电力系统的核心，但会对生态系统造成破坏，因此需要环境流量方案来提升河流系统的生态状况。环境流量评估需要考虑气候变化，因为径流的气候驱动变化会影响水电运营和河流生态系统。在此，我们量化了瑞典北部一个大型调控河流系统在未来气候条件下引入环境流量后水电产量的预期变化以及环境效益。与1981 - 2010年的水文情况相比，预计到2040年，随着气候条件变化径流将增加，按照当前水轮机和水库运行规则，水电产量将增加2.2%。实施环境流量措施会使2040年气候条件下的水电产量损失低于当前：全年引入对零流量事件的限制、向技术鱼类通道和旁路河段放水（伴有季节性流量变化），以及在所有径流式蓄水设施中实现更自然的水位变化，在当前条件下将使年水电产量降低3.5%，到2040年降低3.3%。与此同时，径流增加和引入环境流量的综合影响意味着，2040年气候条件下的年水电产量相比1981 - 2010年仅低0.8%。在所有情景中，预计2040年水库蓄水程度相比1981 - 2010年的情景会增加，并且在基于83年情景的时间序列中，环境流量和水电生产的流量需求均得到满足。本研究证明了在瑞典以及其他预计径流会增加的地区引入环境流量措施的可行性，既能维持水电生产，又能为河流生物多样性带来巨大益处，并增强河流生态系统对气候变化的恢复力。要实现这一目标，需要河流管理利益相关者之间的合作。
