Preprints
https://doi.org/10.5194/egusphere-2024-2580
https://doi.org/10.5194/egusphere-2024-2580
11 Sep 2024
 | 11 Sep 2024
Status: this preprint is open for discussion.

Subglacial and subaerial fluvial sediment transport capacity respond differently to water discharge variations

Ian Delaney, Andrew Tedstone, Mauro A. Werder, and Daniel Farinotti

Abstract. Sediment transport capacity in both subaerial and subglacial channels depends on the shear stress exerted across the channel bottom, which varies with water velocity and channel width. In subaerial channels, water discharge variations are accommodated by flow depth and width changes, along with water velocity. However, in subglacial channels, water is pressurized by the ice above, and they grow in response to frictional heating of water flowing through them. As a result, water discharge changes mainly result in velocity variations, as the channel geometry evolves slowly (over days). Here, we present formulations of sediment transport capacity in different channel types and apply subglacial and subaerial hydraulics models to hydrographs from an Alpine glacier and the Greenland Ice. Numerical experiments show that the changing channel size results in sediment transport capacity peaking before the maximum water discharge. This hysteresis in channel size causes a highly variable relationship between sediment and water discharge in a transport-limited subglacial system. The results also indicate that high subglacial sediment transport capacities can occur across a wide range of water discharges. A second set of numerical experiments shows that subglacial sediment transport is highly non-linear with respect to water discharge, creating more variability in sediment transport capacity. Yet, results and formulations of subglacial sediment transport capacity show that its variability can approach that of subaerial systems when subglacial channel size is in equilibrium with water discharge. The implications of these findings are discussed in the context of sediment discharge from glaciers with different hydro-climatic forcings. We also discuss the impact of different assumptions of channel behavior on sediment transport capacity. These findings can improve the interpretation of sediment discharge records in glacierized catchments.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
Ian Delaney, Andrew Tedstone, Mauro A. Werder, and Daniel Farinotti

Status: open (until 30 Oct 2024)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
Ian Delaney, Andrew Tedstone, Mauro A. Werder, and Daniel Farinotti
Ian Delaney, Andrew Tedstone, Mauro A. Werder, and Daniel Farinotti

Viewed

Total article views: 162 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
130 19 13 162 10 0 2
  • HTML: 130
  • PDF: 19
  • XML: 13
  • Total: 162
  • Supplement: 10
  • BibTeX: 0
  • EndNote: 2
Views and downloads (calculated since 11 Sep 2024)
Cumulative views and downloads (calculated since 11 Sep 2024)

Viewed (geographical distribution)

Total article views: 158 (including HTML, PDF, and XML) Thereof 158 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 05 Oct 2024
Download
Short summary
Sediment transport in rivers and under glaciers depends on water velocity and channel width. In rivers, water discharge changes affect flow depth, width, and velocity. Under glaciers, pressurized water changes velocity more than shape. Due to these differences, this study shows that sediment transport under glaciers varies widely and peaks before water flow does, creating a complex relationship. Understanding these dynamics helps interpret sediment discharge from glaciers in different climates.