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Sediment Yield and its Interannual Variability are Underestimated in Supply-Limited Mountain Basins with Short Records
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  • Jacob Hirschberg,
  • Brian W McArdell,
  • Georgina L Bennett,
  • Peter Molnar
Jacob Hirschberg
Swiss Federal Research Institute WSL

Corresponding Author:jacob.hirschberg@wsl.ch

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Brian W McArdell
Swiss Federal Institute for Forest, Snow and Landscape
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Georgina L Bennett
University of Exeter
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Peter Molnar
ETH Zurich
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Climate and sediment supply are critical factors for the sediment output of geomorphic systems. It is known that non-linearities between forcing and sediment mobilization may lead to dampened or shredded environmental signals in sediment flux measurements. But it is unclear under which circumstances environmental signals, such as extreme events or climate change, are transmitted and measurable downstream. We used a sediment cascade model and a stochastic weather generator to quantify climate forcing effects under a range of sediment supply regimes in a debris-flow catchment in the Swiss Alps (Illgraben). Sediment yields estimated from short records have high uncertainties both in terms of mean and interannual variability, and tend to be underestimated especially in supply-limited systems, where also long-term memory effects driven by sediment storage are evident. Consequently, climate change impact assessments based on short duration records may be grossly inaccurate, and should be extended with uncertainty estimation.