Hydropower alteration of the natural flow and sediment regime can severely degrade hydromorphology, thereby threatening biodiversity and overall ecosystem processes of rivers and their floodplains. Using sequences of aerial images, we quantified seven decades (1938/1942–2013) of spatiotemporal changes in channel and floodplain morphology, as well as changes in the physical habitats, of three floodplain river reaches of the Swiss pre‐Alps, two hydropower‐regulated and one near‐natural. In the Sarine River floodplain, within the first decades of hydropower impairment, the magnitude and frequency of flood events (Q₂, Q₁₀, Q₃₀) decreased substantially. As a result, the area of pioneer floodplain habitats that depend on flood activity and sediment dynamic, such as bare sediments, decreased dramatically by approximately 95%. However, by 2013 vegetated areas had generally increased in comparison to the pre‐regulation period in 1943, indicating general vegetative colonization. Between 1943 and 2013, the active channel underwent essential narrowing (up to 62% width reduction in the residual flow reach) and habitat turnover rates were very low (5% of the total floodplain area changed habitat type five to six times). In contrast, from the 1950s onwards, the near‐natural floodplain of the Sense River experienced recurrent narrowing and widening, and frequent changes between bare and vegetated areas, reflecting the shifting habitat mosaic concept typical for natural floodplains. In the three reaches investigated, we found that the active floodplain width and erosion of vegetated areas were primarily controlled by medium to large floods (Q₁₀, Q₃₀), which combined with reduced time intervals between ordinary floods ≥ Q₂ most likely mobilized streambed sediments and limited the ability of vegetation to establish itself on bare gravel bars within the parafluvial zone. These findings can contribute to restoration action plans such as controlled flooding and sediment replenishments in the Sarine and other floodplain rivers of the Alps. © 2020 John Wiley & Sons, Ltd.

中文翻译：

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瑞士西部近自然（Sense河）和水电调节（Sarine河）阿尔卑斯山前河漫滩的七十年水文地貌变化

水力发电对自然流量和沉积物状态的改变会严重破坏水文形态，从而威胁到河流及其洪泛区的生物多样性和整个生态系统进程。我们使用航空影像序列对瑞士阿尔卑斯山前三个洪泛区河段，两个水力发电站的河道和洪泛区形态的时空变化以及自然栖息地的变化进行了七十年（1938 / 1942–2013）的量化。监管和近自然。在萨林河洪泛区，在水电损害的头十年内，洪水事件的数量和频率（Q ₂，Q ₁₀，Q ₃₀）大幅下降。结果，取决于洪水活动和沉积物动态（如裸露沉积物）的先锋洪泛区生境面积急剧减少了约95％。但是，与1943年的法规前时期相比，到2013年，植被面积总体上有所增加，这表明植物群落普遍存在。在1943年至2013年之间，活动航道经历了必不可少的变窄（剩余流段宽度最多减少62％），栖息地周转率非常低（占总洪泛区面积的5％，改变了栖息地类型五至六次）。相反，从1950年代开始，Sense River的近自然洪泛区经历了反复的变窄和拓宽，裸露和植被区之间的变化频繁，这反映了自然洪泛区特有的栖息地镶嵌概念的变化。Q ₁₀，Q ₃₀），它与普通的洪水≥之间减少的时间间隔组合的Q ₂最可能的动员河床沉积物和限制植被到parafluvial区内建立本身上裸砾石杆的能力。这些发现可有助于恢复行动计划，例如在阿尔卑斯山的萨因勒河和其他洪泛区河流中控制洪水和沉积物补充。分级为4 +©2020 John Wiley＆Sons，Ltd.