Modelling impacts of spatially variable erosion drivers on suspended sediment dynamics
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Date
2020-07-16
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Journal Article
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yes
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Abstract
Suspended sediment load in rivers is highly uncertain because sediment production and transport at catchment scale are strongly variable in space and time, and they are affected by catchment hydrology, topography, and land cover. Among the main sources of this variability are the spatially distributed nature of overland flow as an erosion driver and of surface erodibility given by soil type and vegetation cover distribution. Temporal variability mainly results from the time sequence of rainfall intensity during storms and snowmelt leading to soil saturation and overland flow. We present a new spatially distributed soil erosion and suspended sediment transport module integrated into the computationally efficient physically based hydrological model TOPKAPI-ETH, with which we investigate the effects of the two erosion drivers - precipitation and surface erodibility - on catchment sediment fluxes in a typical pre-Alpine mesoscale catchment. By conducting a series of numerical experiments, we quantify the impact of spatial variability in the two key erosion drivers on erosion-deposition patterns, sediment delivery ratio, and catchment sediment yields. Main findings are that the spatial variability in erosion drivers affects sediment yield by (i) increasing sediment production due to a spatially variable precipitation, while decreasing it due to a spatially variable surface erodibility, (ii) favouring the clustering of sediment source areas in space by surface runoff generation, and (iii) decreasing their connectivity to the river network by magnifying sediment buffers. The results highlight the importance of resolving spatial gradients controlling hydrology and sediment processes when modelling sediment dynamics at the mesoscale, in order to capture the key effects of sediment sources, buffers, and hillslope hydrological pathways in determining the sediment signal.
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published
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Journal / series
Volume
8 (3)
Pages / Article No.
619 - 635
Publisher
Copernicus
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03473 - Burlando, Paolo (emeritus) / Burlando, Paolo (emeritus)
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Funding
690268 - Use of a Decision-Analytic Framework to explore the water-energy-food NExus in complex and trans-boundary water resources systems of fast growing developing countries. (SBFI)
Related publications and datasets
Is new version of: https://doi.org/10.3929/ethz-b-000390849
Is supplemented by: https://doi.org/10.3929/ethz-b-000358874