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Different geomorphic processes control suspended sediment and bedload export from glaciers
Ian Delaney1, Frédéric Lardet2,3, Matt Jenkin2
1Institut des Dynamique de la Surface Terrestre (IDYST), Université de Lausanne Bâtiment Géopolis, CH-1015, Lausanne, Switzerland. IanArburua.Delaney@unil.ch.
Nature Communications
|July 2, 2025
Summary
Glacier changes affect sediment export. Both suspended and bedload sediment are exported in comparable amounts, but bedload transport is less efficient due to subglacial hydraulics.
Area of Science:
- Glaciology
- Environmental Science
- Hydrology
Background:
- Cryospheric changes significantly alter sediment export from glacierized catchments.
- This impacts downstream ecosystems and infrastructure, such as hydropower.
- Understanding subglacial bedload transport is limited due to observational difficulties.
Purpose of the Study:
- To elucidate factors controlling sediment export from Alpine glaciers.
- To compare suspended sediment and bedload transport processes.
- To investigate the role of subglacial hydraulics in sediment evacuation.
Main Methods:
- Utilized a physically-based numerical model for subglacial sediment production and transport.
- Inverted the model using suspended sediment and continuous bedload discharge records.
- Analyzed Alpine glacier data.
Main Results:
- Comparable quantities of suspended sediment and bedload are exported.
- Both sediment types depend on sediment availability for transport.
- Bedload export is influenced by subglacial channel hydraulics (shape, roughness), making it less efficient than fine sediment transport.
Conclusions:
- Subglacial hydraulics must be explicitly considered in bedload export studies.
- Suspended and bedload transport should be analyzed separately.
- Inefficient meltwater-driven bedload evacuation suggests non-fluvial mechanisms are crucial for continued glacial erosion.
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