Proglacial erosion rates and processes in a glacierized catchment in the Swiss Alps

Ian Delaney,Andreas Bauder,Matthias Huss,Yvo Weidmann

doi:10.1002/esp.4239

Ian Delaney, Andreas Bauder + Show 2 more

Open Access

https://doi.org/10.1002/esp.4239

Copy DOI

Abstract

AbstractIn the Swiss Alps, climatic changes have not only caused glacier retreat, but also likely increased sedimentation downstream of glaciers. This material either originates from below the glacier or from periglacial environments, which are exposed as glaciers retreat, and often consist of easily erodible sediment. Griesgletscher's catchment in the Swiss Alps was examined to quantify erosion in the proglacial area, possible hydrological drivers and contributions of the sub‐ and periglacial sources. Digital elevation models, created from annual aerial photographs, were subtracted to determine annual volume changes in the proglacial area from 1986 to 2014. These data show a strong increase in proglacial erosion in the decade prior to 2012, coincident with increasing proglacial area size. However, examination of the gradient between discharge and sediment evacuation, and modeled sediment transport, could suggest that the proglacial area began to stabilize and sediment supply is limited. The large influx of sediment into the proglacial reservoir, which is roughly 2.5 times greater than the amount of sediment eroded from the proglacial area, demonstrates the importance of subglacial erosion to the catchment's sediment budget. Although far more sediment originates subglacially, erosion rates in the proglacial area are over 50 times greater than the rest of the catchment. In turn, both sub‐ and periglacial processes, in addition to constraining sediment supply, must be considered for assessing future sediment dynamics as glacier area shrinks and proglacial areas grow. © 2017 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.

Highlights

Glaciated catchments are characterized by exceptional amounts of sediment transport and erosion compared to their fluvial counterparts (e.g. Hallet et al, 1996; Einsele and Hinderer, 1997)
In 2013 the proglacial area experienced a marginal amount of net erosion, and the measured amount is underestimated, these results suggest a large amount of subglacial erosion occurred during this year
Analysis of the digital elevation models (DEMs) spanning the 28 years suggests that 125 600 m3 of material was removed from the proglacial area over this time and not replenished

Summary

Introduction

Glaciated catchments are characterized by exceptional amounts of sediment transport and erosion compared to their fluvial counterparts (e.g. Hallet et al, 1996; Einsele and Hinderer, 1997). Sediment production rates in the Alps are only surpassed by other glaciated regions in Alaska and Central Asia (Hallet et al, 1996). New periglacial areas form as glaciers retreat and are often a rich source of sediment available for transport by fluvial or mass-wasting activity Church and Ryder, 1972; Fenn and Gomez, 1989; Warburton, 1990; Ballantyne, 2002a); the relative contribution of periglacial and subglacial sediment to total sediment discharge in a catchment varies greatly between basins (Fenn and Gomez, 1989; Mao et al, 2014; Guillon et al, 2015) New periglacial areas form as glaciers retreat and are often a rich source of sediment available for transport by fluvial or mass-wasting activity (e.g. Church and Ryder, 1972; Fenn and Gomez, 1989; Warburton, 1990; Ballantyne, 2002a); the relative contribution of periglacial and subglacial sediment to total sediment discharge in a catchment varies greatly between basins (Fenn and Gomez, 1989; Mao et al, 2014; Guillon et al, 2015)

Objectives

Methods

Results

Conclusion