Successful river restoration requires understanding and integration of multiple disciplinary perspectives, including evaluations of past and ongoing watershed processes, local geomorphic response, and impacts unique to human activity. Nowhere is this more apparent than along the Merced River in Yosemite National Park, USA, where both an outstanding natural landscape and the consequences of over a century of human disturbances continue to interact. An intact upstream watershed highlights the importance here of local impacts on geomorphic response. Incision and the resulting decoupling of the channel from its adjacent late‐Holocene floodplain are consequences of reduced channel roughness, likely from de‐snagging the river, and instream gravel mining in the 19th and early 20th century. Riparian‐zone disturbance by visitor use has damaged riparian vegetation and soils, inducing channel widening. Revetments and channel‐spanning bridges, the latter being visible and oft‐cited impacts to fluvial processes, have distorted the natural evolution of meanders and induced local channel narrowing. The historical rate of sediment export from Yosemite Valley has greatly exceeded replenishment from upstream and lateral sources, creating a deficit that now inhibits recovery via passive restoration of more natural channel form and function. Climate change may amplify now‐diminished fluvial processes but also exacerbate the rate of sediment export. These conditions, reflecting a complex intersection of geologic history, modern geomorphic processes, and human interactions, demonstrate how a limited influx of sediment coupled with intensive human use can have long‐term consequences for riverine conditions, restoration opportunities, and social engagement with the riverine landscape.

中文翻译：

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通过美国优胜美地国家公园的优胜美地山谷恢复默塞德河的机遇与挑战

成功的河流修复需要理解和整合多种学科观点，包括对过去和正在进行的分水岭过程的评估，局部地貌反应以及人类活动所特有的影响。在美国优胜美地国家公园的默塞德河沿岸，这是最明显的地方，那里优美的自然景观和一个多世纪以来的人类骚乱的后果继续相互作用。一个完整的上游流域突出了这里对地貌响应的局部影响的重要性。切口和由此导致的河道与邻近的全新世晚期洪泛区的脱钩是河道粗糙度降低的结果，这很可能是由于河道下垂以及19世纪和20世纪初的河床砾石开采所致。访客对河岸带的干扰破坏了河岸植被和土壤，导致河道拓宽。护岸和跨河桥梁，后者是对河流过程的可见且经常被引用的冲击，扭曲了河曲的自然演化并导致了局部河道的狭窄。优胜美地山谷的沉积物出口的历史速度大大超过了上游和侧向来源的补给，造成了赤字，现在这种赤字通过被动恢复更多自然通道的形式和功能而抑制了恢复。气候变化可能会加剧现在减少的河流过程，但也会加剧沉积物的出口速度。这些情况反映了地质历史，现代地貌过程和人类相互作用的复杂交集，