Glacier Ice Thickness Estimation and Future Lake Formation in Swiss Southwestern Alps—The Upper Rhône Catchment: A VOLTA Application

Abstract

Glacial lake formations are currently being observed in the majority of glacierized mountains in the world. Given the ongoing climate change and population increase, studying glacier ice thickness and bed topography is a necessity for understanding the erosive power of glacier activity in the past and lake formation in the future. This study uses the available information to predict potential sites for future lake formation in the Upper Rhône catchment located in the Southwestern Swiss Alps. The study integrates the latest available glacier outlines and high-quality digital elevation models (DEMs) into the Volume and Topography Automation (VOLTA) model to estimate ice thickness within the extent of the glacier. Unlike the previous ice thickness models, VOLTA calculates ice thickness distribution based on automatically-derived centerlines, while optimizing the model by including the valley side drag parameter in the force equation. In this study, a total ice volume of 37.17 ± 12.26 km3 (1σ) was estimated for the Upper Rhône catchment. The comparison of VOLTA performance indicates a stronger relationship between measured and predicted bedrock, confirming the less variability in VOLTA’s results (r2 ≈ 0.92) versus Glacier Bed Topography (GlabTop) (r2 ≈ 0.82). Overall, the mean percentage of ice thickness error for all measured profiles in the Upper Rhône catchment is around ±22%, of which 28 out of 42 glaciers are underestimated. By incorporating the vertical accuracy of free-ice DEM, we could identify 171 overdeepenings. Among them, 100 sites have a high potential for future lake formation based on four morphological criteria. The visual evaluation of deglaciated areas also supports the robustness of the presented methodology, as 11 water bodies were already formed within the predicted overdeepenings. In the wake of changing global climate, such results highlight the importance of combined datasets and parameters for projecting the future glacial landscapes. The timely information on future glacial lake formation can equip planners with essential knowledge, not only for managing water resources and hazards, but also for understanding glacier dynamics, catchment ecology, and landscape evolution of high-mountain regions.

Ice thickness distribution of all Swiss glaciers based on extended ground-penetrating radar data and glaciological modeling

“…Such a map, for example, contains information on glacier bed overdeepenings, which can be further analyzed with regard to their potential for the formation of future proglacial lakes. Based on the glacier bed topography and the distribution of today's ice volume, various studies have aimed at predicting the size and the formation time of such lakes in the Alps (Frey and others, 2010;Linsbauer and others, 2012;Gharehchahi and others, 2020;Magnin and others, 2020;Shugar and others, 2020). Such information is important since future lakes might change the hazard situation in the corresponding regions, or can be large enough to be of economic interest for tourism, fresh water supply or in the context of hydropower (Haeberli and others, 2016).…”

Local- and Regional-Scale Forcing of Glacier Mass Balance Changes in the Swiss Alps

“…Even with a rich literature dedicated to monitoring long-term glacier trends, there is still a further need to perform time series analysis to quantify Swiss glacier mass balance changes and drivers as they relate to local and remote climatic conditions, specifically for glaciers included in newly developed datasets [33]. Moreover, there is a special need to study the development and evolution of catchments through ice melt and associated features such as new lakes, since they are closely tied to glacier ice loss [46]. As such, our study employed glaciological, remote sensing, and climate datasets and assessed glacier mass balance components and hypsometric characteristics with respect to interactions with local meteorological variables and remote large-scale atmospheric and oceanic patterns to more comprehensively understand physical processes driving glacier mass balance variability.…”

Volume, formation and sedimentation of future glacier lakes in Switzerland

“…Several studies aiming at such an anticipation of future glacier lakes exist, notably for (parts of) High Mountain Asia (Linsbauer et al, 2016;Kapitsa et al, 2017;Zheng et al, 2021), the Andes (Colonia et al, 2017;Drenkhan et al, 2018), or the European Alps (Linsbauer et al, 2012;Magnin et al, 2020;Viani et al, 2020;Gharehchahi et al, 2020). For the Swiss Alps, Linsbauer et al (2012) estimated that between 400 and 600 new glacier lakes could form if glaciers were to vanish entirely, with a total area in the order of 50 to 60 km 2 and a total volume of about 2 km 3 .…”