Climate change impacts on sediment production and transfer processes on hillslopes and through channels are governed by possible changes in precipitation, runoff, and air temperature. These hydrological and geomorphological impacts are difficult to predict in temperature‐sensitive Alpine environments. In this study, we combined a stochastic weather generator model with the most current climate change projections to feed a hillslope‐channel sediment cascade model for a major debris‐flow system in the Swiss Alps (the Illgraben). This allowed us to quantify climate change impacts and their uncertainties on sediment yield and the number of debris flows at hourly temporal resolution. We show that projected changes in precipitation and air temperature lead to a reduction in both sediment yield (−48%) and debris‐flow occurrence (−23%). This change is caused by a decrease in sediment supply from hillslopes, which is driven by frost‐weathering. Additionally, we conduct model experiments that show the sensitivity of projected changes in sediment yield and debris‐flow hazard to basin elevation, with important implications for assessing natural hazards and risks in mountain environments. Future changes in hydrological and sediment fluxes are characterized by high uncertainty, mainly due to irreducible internal climate variability. Therefore, this stochastic uncertainty needs to be considered in climate change impact assessments for geomorphic systems.

中文翻译：

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气候变化对高山流域沉积物产量和泥石流活动的影响

气候变化对坡面和河道沉积物生产和转移过程的影响受降水，径流和气温的可能变化控制。这些水文和地貌影响在温度敏感的高山环境中很难预测。在这项研究中，我们将随机天气生成器模型与最新的气候变化预测相结合，为瑞士阿尔卑斯山（伊尔格拉本）的主要泥石流系统提供了一条斜坡通道沉积物级联模型。这使我们能够以小时时间分辨率来量化气候变化的影响及其对沉积物产量和泥石流数量的不确定性。我们表明，预计的降水量和气温变化会导致沉积物收率（−48％）和泥石流发生率（−23％）降低。这种变化是由于霜冻风化导致山坡沉积物供应减少所致。此外，我们进行的模型实验表明沉积物产量和泥石流灾害的预计变化对盆地海拔的敏感性，对评估山区环境中的自然灾害和风险具有重要意义。未来水文和泥沙通量的变化具有高度不确定性的特征，这主要是由于内部气候变化不可减少。因此，在地貌系统的气候变化影响评估中需要考虑这种随机不确定性。我们进行的模型实验表明，沉积物产量和泥石流灾害的预计变化对盆地海拔的敏感性，对于评估山区环境中的自然灾害和风险具有重要意义。未来水文和泥沙通量的变化具有高度不确定性的特征，这主要是由于内部气候变化不可减少。因此，在地貌系统的气候变化影响评估中需要考虑这种随机不确定性。我们进行的模型实验表明沉积物产量和泥石流灾害的预测变化对盆地海拔的敏感性，对评估山区环境中的自然灾害和风险具有重要意义。未来水文和泥沙通量的变化具有高度不确定性的特征，这主要是由于内部气候变化不可减少。因此，在地貌系统的气候变化影响评估中需要考虑这种随机不确定性。