Suspended sediment concentrations in Alpine rivers: from annual regimes to sub-daily extreme events

<p>The occurrence of extreme suspended sediment concentrations (SSCs) in rivers can have negative impacts on human infrastructure, water quality, and the health of aquatic ecosystems. However, most existing studies have focused on the SSC dynamics of individual catchments or single events. Con...

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Main Authors: A. van Hamel, P. Molnar, J. Janzing, M. I. Brunner
Format: Article
Language:English
Published: Copernicus Publications 2025-07-01
Series:Hydrology and Earth System Sciences
Online Access:https://hess.copernicus.org/articles/29/2975/2025/hess-29-2975-2025.pdf
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author A. van Hamel
A. van Hamel
A. van Hamel
P. Molnar
J. Janzing
J. Janzing
J. Janzing
M. I. Brunner
M. I. Brunner
M. I. Brunner
author_facet A. van Hamel
A. van Hamel
A. van Hamel
P. Molnar
J. Janzing
J. Janzing
J. Janzing
M. I. Brunner
M. I. Brunner
M. I. Brunner
author_sort A. van Hamel
collection DOAJ
description <p>The occurrence of extreme suspended sediment concentrations (SSCs) in rivers can have negative impacts on human infrastructure, water quality, and the health of aquatic ecosystems. However, most existing studies have focused on the SSC dynamics of individual catchments or single events. Consequently, large-scale patterns of suspended sediment dynamics remain poorly understood. The objective of this study is to identify spatial differences in (1) the seasonality of SSCs and (2) the occurrence of SSC extremes in the Alps. For our analyses, we use 10 years of observed sub-daily SSC data from 38 gauging stations in Switzerland and Austria.</p> <p>We show that the presence of glaciers, catchment elevation, and the onset of the melt season are important drivers of SSC seasonality. However, slightly different processes are important at the event scale, where rainfall is the main driver of SSC extremes, responsible for 85 % of all events. The remaining events are entirely or partly associated with snowmelt and glacial melt, which can account for up to 35 % of the events in high-elevation and partially glaciated catchments. This underscores the disproportionate influence of meltwater on sediment concentrations in high-altitude alpine rivers, which can be explained by the significant contribution of meltwater to overland flow and river discharge in combination with the high sediment availability in glacier forefields. A significant proportion of the extreme events (24 %) resulted in peak SSC values greater than 5 g L<span class="inline-formula"><sup>−1</sup></span>, highlighting their potential to cause significant harm to aquatic species and river ecosystems.</p>
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spelling doaj-art-0a5fdac6b07b4a7d96c172ddf33654602025-08-20T02:39:09ZengCopernicus PublicationsHydrology and Earth System Sciences1027-56061607-79382025-07-01292975299510.5194/hess-29-2975-2025Suspended sediment concentrations in Alpine rivers: from annual regimes to sub-daily extreme eventsA. van Hamel0A. van Hamel1A. van Hamel2P. Molnar3J. Janzing4J. Janzing5J. Janzing6M. I. Brunner7M. I. Brunner8M. I. Brunner9WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, SwitzerlandDepartment of Environmental Systems Science, Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, SwitzerlandClimate Change, Extremes and Natural Hazards in Alpine Regions Research Center CERC, Davos Dorf, SwitzerlandDepartment of Civil, Environmental and Geomatic Engineering, Institute of Environmental Engineering, ETH Zurich, Zurich, SwitzerlandWSL Institute for Snow and Avalanche Research SLF, Davos Dorf, SwitzerlandDepartment of Environmental Systems Science, Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, SwitzerlandClimate Change, Extremes and Natural Hazards in Alpine Regions Research Center CERC, Davos Dorf, SwitzerlandWSL Institute for Snow and Avalanche Research SLF, Davos Dorf, SwitzerlandDepartment of Environmental Systems Science, Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, SwitzerlandClimate Change, Extremes and Natural Hazards in Alpine Regions Research Center CERC, Davos Dorf, Switzerland<p>The occurrence of extreme suspended sediment concentrations (SSCs) in rivers can have negative impacts on human infrastructure, water quality, and the health of aquatic ecosystems. However, most existing studies have focused on the SSC dynamics of individual catchments or single events. Consequently, large-scale patterns of suspended sediment dynamics remain poorly understood. The objective of this study is to identify spatial differences in (1) the seasonality of SSCs and (2) the occurrence of SSC extremes in the Alps. For our analyses, we use 10 years of observed sub-daily SSC data from 38 gauging stations in Switzerland and Austria.</p> <p>We show that the presence of glaciers, catchment elevation, and the onset of the melt season are important drivers of SSC seasonality. However, slightly different processes are important at the event scale, where rainfall is the main driver of SSC extremes, responsible for 85 % of all events. The remaining events are entirely or partly associated with snowmelt and glacial melt, which can account for up to 35 % of the events in high-elevation and partially glaciated catchments. This underscores the disproportionate influence of meltwater on sediment concentrations in high-altitude alpine rivers, which can be explained by the significant contribution of meltwater to overland flow and river discharge in combination with the high sediment availability in glacier forefields. A significant proportion of the extreme events (24 %) resulted in peak SSC values greater than 5 g L<span class="inline-formula"><sup>−1</sup></span>, highlighting their potential to cause significant harm to aquatic species and river ecosystems.</p>https://hess.copernicus.org/articles/29/2975/2025/hess-29-2975-2025.pdf
spellingShingle A. van Hamel
A. van Hamel
A. van Hamel
P. Molnar
J. Janzing
J. Janzing
J. Janzing
M. I. Brunner
M. I. Brunner
M. I. Brunner
Suspended sediment concentrations in Alpine rivers: from annual regimes to sub-daily extreme events
Hydrology and Earth System Sciences
title Suspended sediment concentrations in Alpine rivers: from annual regimes to sub-daily extreme events
title_full Suspended sediment concentrations in Alpine rivers: from annual regimes to sub-daily extreme events
title_fullStr Suspended sediment concentrations in Alpine rivers: from annual regimes to sub-daily extreme events
title_full_unstemmed Suspended sediment concentrations in Alpine rivers: from annual regimes to sub-daily extreme events
title_short Suspended sediment concentrations in Alpine rivers: from annual regimes to sub-daily extreme events
title_sort suspended sediment concentrations in alpine rivers from annual regimes to sub daily extreme events
url https://hess.copernicus.org/articles/29/2975/2025/hess-29-2975-2025.pdf
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