A probabilistic sediment cascade model of sediment transfer in the Illgraben

Bennett, Georgina, Molnar, Peter, McArdell, Brian and Burlando, Paulo (2014) A probabilistic sediment cascade model of sediment transfer in the Illgraben. Water Resources Research, 50 (2). 1225–1244. ISSN 0043-1397

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Abstract

We present a probabilistic sediment cascade model to simulate sediment transfer in a mountain basin (Illgraben, Switzerland) where sediment is produced by hillslope landslides and rockfalls and exported out of the basin by debris flows and floods. The model conceptualizes the fluvial system as a spatially lumped cascade of connected reservoirs representing hillslope and channel storages where sediment goes through cycles of storage and remobilization by surface runoff. The model includes all relevant hydrological processes that lead to runoff formation in an Alpine basin, such as precipitation, snow accumulation, snowmelt, evapotranspiration, and soil water storage. Although the processes of sediment transfer and debris flow generation are described in a simplified manner, the model produces complex sediment discharge behavior which is driven by the availability of sediment and antecedent wetness conditions (system memory) as well as the triggering potential (climatic forcing). The observed probability distribution of debris flow volumes and their seasonality in 2000–2009 are reproduced. The stochasticity of hillslope sediment input is important for reproducing realistic sediment storage variability, although many details of the hillslope landslide triggering procedures are filtered out by the sediment transfer system. The model allows us to explicitly quantify the division into transport and supply-limited sediment discharge events. We show that debris flows may be generated for a wide range of rainfall intensities because of variable antecedent basin wetness and snowmelt contribution to runoff, which helps to understand the limitations of methods based on a single rainfall threshold for debris flow initiation in Alpine basins.

Item Type: Article
Uncontrolled Keywords: sediment cascade,landslides,debris flows,sediment discharge,stochastic modeling
Faculty \ School: Faculty of Science > School of Environmental Sciences
Depositing User: Pure Connector
Date Deposited: 10 May 2017 05:05
Last Modified: 24 Nov 2020 01:06
URI: https://ueaeprints.uea.ac.uk/id/eprint/63446
DOI: 10.1002/2013WR013806

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