27 Jun 2022
27 Jun 2022
Status: this preprint is open for discussion.

Modelling large‐scale landform‐evolution with a stream‐power law for glacial erosion (OpenLEM v37): Benchmarking experiments against a more process-based description of ice flow (iSOSIA v3.4.3)

Moritz Liebl1, Jörg Robl1, Stefan Hergarten2, David Lundbek Egholm3, and Kurt Stüwe4 Moritz Liebl et al.
  • 1Department of Environment and Biodiversity, University of Salzburg, 5020 Salzburg, Austria
  • 2Institute of Earth and Environmental Sciences, University of Freiburg, 79104 Freiburg, Germany
  • 3Department of Geoscience, Aarhus University, 8000 Aarhus, Denmark
  • 4Department of Earth Science, University of Graz, 8020 Graz, Austria

Abstract. Following the tradition of modeling fluvial landscape evolution, a novel approach describing glacial erosion based on an empirical stream power law was proposed. This approach differs substantially from well established process-based models applied to describe glacial erosion in mountain landscapes. Outstanding computational performance but a number of potential limitations compared to process-based models requires extensive testing to evaluate the applicability of this novel approach. In this study, we test the validity of the glacial stream power law and its implementation into a 2-D landform evolution model (OpenLEM) by benchmarking it against a state of the art surface process model based on the integrated second order shallow-ice approximation (iSOSIA).

Despite completely different approaches, OpenLEM and iSOSIA predict similar ice flow patterns and erosion rates for a wide range of climatic conditions without re-adjusting a set of calibrated scaling parameters. This parameter set is valid for full glacial conditions where the entire precipitation is converted to ice but also for an altitude-dependent glacier mass balance as characteristic for most glaciated mountain ranges on Earth.

In both models characteristic glacial features, such as overdeepenings, hanging valleys, and steps at confluences emerge roughly at the same locations resulting in a consistent altitude-dependent adjustment of channel slope and relief. Compared to iSOSIA, however, distinctly higher erosion rates occur in OpenLEM at valley flanks during the initial phase of the fluvial to glacial transition. This is mainly due to the simplified description of glacier width and ice surface in OpenLEM.

In this respect, we found that the glacial stream power approach cannot replace process-based models such as iSOSIA, but is complementary to them by addressing research questions that could not previously be answered due to a lack of computational efficiency. The implementation of the glacial stream power law is primarily suitable for large-scale simulations investigating the evolution of mountain topography in the interplay of tectonics and climate. As coupling glacial and fluvial erosion with sediment transport shows nearly the same computationally efficiency as its purely fluvial counterpart, mountain range scale simulations at high spatial resolution are not exclusively restricted to the fluvial domain anymore and a series of exciting research questions can be attacked by this novel approach.

Moritz Liebl et al.

Status: open (until 22 Aug 2022)

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Moritz Liebl et al.

Model code and software

egusphere-2022-352 Moritz Liebl

Video supplement

egusphere-2022-352-videos Moritz Liebl

Moritz Liebl et al.


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Short summary
In this study, we benchmark a topography-based model for glacier erosion (OpenLEM) with a well-established process-based model (iSOSIA). Our experiments show that large-scale erosion patterns and, in particular, the transformation of valley length geometry from fluvial to glacial conditions are very similar in both models. This finding enables the application of OpenLEM to study the influence of climate and tectonics on glaciated mountains with reasonable computational effort on standard PCs.