A multi-level strategy for anticipating future glacier lake formation and associated hazard potentials

Abstract

Abstract. In the course of glacier retreat, new glacier lakes can develop. As such lakes can be a source of natural hazards, strategies for predicting future glacier lake formation are important for an early planning of safety measures. In this article, a multi-level strategy for the identification of overdeepened parts of the glacier beds and, hence, sites with potential future lake formation, is presented. At the first two of the four levels of this strategy, glacier bed overdeepenings are estimated qualitatively and over large regions based on a digital elevation model (DEM) and digital glacier outlines. On level 3, more detailed and laborious models are applied for modeling the glacier bed topography over smaller regions; and on level 4, special situations must be investigated in-situ with detailed measurements such as geophysical soundings. The approaches of the strategy are validated using historical data from Trift Glacier, where a lake formed over the past decade. Scenarios of future glacier lakes are shown for the two test regions Aletsch and Bernina in the Swiss Alps. In the Bernina region, potential future lake outbursts are modeled, using a GIS-based hydrological flow routing model. As shown by a corresponding test, the ASTER GDEM and the SRTM DEM are both suitable to be used within the proposed strategy. Application of this strategy in other mountain regions of the world is therefore possible as well.

Glacial lake outburst flood risk in Himachal Pradesh, India: an integrative and anticipatory approach considering current and future threats

“…5b). This value of 25°was found to best capture the classical situation described by Frey et al (2010), where following the retreat of ice over a steep break in topography, we can be most confident that a future lake will form behind a steep dam. From this selection process, 279 potential new lakes were identified across the state of HP (see Table 2, and examples shown in Fig.…”

“…Such retreat would be sufficient to expose the bed topography within the current ablation areas of most glaciers. In a final selection step, a key topographic criterion for lake formation established by Frey et al (2010) was automated to identify only those overdeepenings located above a sudden steepening in topography. This steepening was approximated by mean slope values [25°within a zone 300 m immediately below the overdeepening and identifies situations where there is a higher likelihood of a thick overdeepened part of the glacier occurring, with steeper, thinner ice below (see overdeepening 2 in Fig.…”

“…Such lakes will mostly form in depressions or overdeepenings in the exposed glacier bed (Frey et al 2010) and will be dammed by bedrock or moraine, depending on the glacier type, erosional properties, and rate of retreat . Typically for lakes to be impounded by large moraine dams, such as formed during the LIA, the glacier front must remain stationary for a sufficient length of time.…”

Evolution of glacier-dammed lakes through space and time; Brady Glacier, Alaska, USA

“…Rapid changes in the cryosphere are leading to hazardous situations with few, if any, historical precedents (Frey et al, 2010). Early identification of future jökulhlaups requires an understanding of the jökulhlaup cycle.…”

“…Climate is changing at an unprecedented rate, especially at high latitudes (Trenberth et al, 2007), and glacial lakes evolve rapidly under such conditions; glacier equilibrium is disrupted and hazard zones shift beyond those of historical knowledge (Frey et al, 2010). The recent increase in the rate of retreat and downwasting of alpine glaciers worldwide has accelerated the formation and evolution of glacier-dammed lakes (Kääb et al, 2003;Kargel et al, 2005).…”