Abstract
AbstractBedrock overdeepenings exposed by continued glacial retreat can store precipitation and meltwater, potentially leading to the formation of new proglacial lakes. These lakes may pose threats of glacial lake outburst floods (GLOFs) in high mountain areas, particularly if new lakes form in geomorphological setups prone to triggering events such as landslides or moraine collapses. We present the first complete inventory for future glacial lakes in High Mountain Asia by computing the subglacial bedrock for ~100 000 glaciers and estimating overdeepening area, volume and impact hazard for the larger potential lakes. We detect 25 285 overdeepenings larger than 104m2with a volume of 99.1 ± 28.6 km3covering an area of 2683 ± 773.8 km2. For the 2700 overdeepenings larger than 105m2, we assess the lake predisposition for mass-movement impacts that could trigger a GLOF by estimating the hazard of material detaching from surrounding slopes. Our findings indicate a shift in lake area, volume and GLOF hazard from the southwestern Himalayan region toward the Karakoram. The results of this study can be used for anticipating emerging threats and potentials connected to glacial lakes and as a basis for further studies at suspected GLOF hazard hotspots.
Highlights
Rising temperatures cause increased glacial melting in most glaciated regions of the world (Hock and others, 2019b)
As our study indicates the development of large future lakes will focus on the northwestern part of High Mountain Asia (HMA), adaptation measures taken in the southwestern Himalayan region (Bajracharya, 2009; Mahagaonkar and others, 2017) will need to be considered and adopted by communities in the Karakoram and Pamir as well
This study provides the first complete inventory of future glacial lakes >104 m2 in area in HMA by computing the bedrock topography of the ∼100 000 glaciers in the region using ice thickness data of a five-model-ensemble by Farinotti and others (2019a) and the Advanced Land Observing Satellite (ALOS) World 3D-30m (AW3D30) DEM
Summary
Rising temperatures cause increased glacial melting in most glaciated regions of the world (Hock and others, 2019b). This holds especially true for the mountain ranges of High Mountain Asia (HMA) (Shean and others, 2020). Dam failures can be triggered by thawing permafrost or by displacement waves from rockfall, ice avalanches or calving (Kershaw and others, 2005; Harrison and others, 2018). Both types of events can lead to reduced material cohesion and/or subsequent dam erosion (Eriksson and others, 2009). For example, the development of early warning systems (Huggel and others, 2020), decision making strategies (Cuellar and McKinney, 2017) or inventories of lakes and previous flood events (Nagai and others, 2017; Nie and others, 2018)
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