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: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-07-01
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| 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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| Summary: | <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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| ISSN: | 1027-5606 1607-7938 |