Brief Communication: The Khurdopin glacier surge revisited – extreme flow velocities and formation of a dammed lake in 2017

Abstract

Abstract. Glacier surges occur regularly in the Karakoram but the driving mechanisms, their frequency and its relation to a changing climate remain unclear. In this study we use digital elevation models and Landsat imagery in combination with high-resolution imagery from the Planet satellite constellation to quantify surface elevation changes and flow velocities during a glacier surge in of the Khurdopin glacier in 2017. Results reveal that an accumulation of ice mass above a clearly defined steep section of the glacier tongue since the last surge in 1999 eventually leads to a rapid surge in May 2017 peaking with velocities above 5000 m a−1, which is among the fastest rates globally for a mountain glacier. The time series of Landsat imagery reveals that velocities increase steadily during a four-year build-up phase prior to the actual surge and that the surge front advances towards the terminus after the peak has passed on the upper tongue. The surge frequency between the reported surges remains relatively constant at 18 (1999 to 2017) and 20 (1979 to 1999) years respectively. It is hypothesized that the surge is mainly initiated as a result of increased pressure melting caused by ice accumulation, i.e. the thermal switch hypothesis. However, surface observations show increased crevassing and disappearance of supra glacial ponds, which could have led to increased lubrication of the glacier bed. Finally, we observe that the surging glacier blocks the river in the valley and causes a lake to form, which may grow in subsequent years and could pose threats to downstream settlements and infrastructure in case of a sudden breach.

The hazardous 2017–2019 surge and river damming by Shispare Glacier, Karakoram

“…S11). Other maximum reported velocities are for Hispar (~14 m d −1 ), Khurdopin (~15 m d −1 ) and Staghar (~10 m d −1 ) glaciers 20,23,24,27 (Supplementary Fig. S11).…”

“…Active surges pose dangerous hazards for local communities, threatening destruction of critical infrastructure when ice overrides villages, roads, bridges, and trails. Furthermore, if the glacier advances across river valleys and forms an ice-dammed lake, it may result in devastating outburst floods [21][22][23][24] . Therefore, monitoring of glacier surges, ice-dammed lake formation and drainage is essential.…”

“…fluctuations in surface melt elevation. Several studies in the Karakoram have utilized remote sensing data to study glacier surge dynamics 19,20,[23][24][25][26][27]33,34 . More recently, Rashid et al 35 reported the recent surge of Shispare Glacier using remote sensing observations.…”

Geospatial Analysis and Simulation of Glacial Lake Outburst Flood Hazard in Hunza and Shyok Basins of Upper Indus Basin

“…The frequency of glacier-dammed lakes and outburst floods in the Karambar valley of Hindukush-Karakoram has increased the risk to infrastructure and living organisms in this region (Iturrizaga, 2005). The glacier surge is a seasonal phenomenon owing to the extreme flow velocities resulting in the formation of a dammed lake (Steiner et al, 2018). The balance in accumulation and ablation zones of a glacier is very vital for its stability.…”

More dynamic than expected: An updated survey of surging glaciers in the Pamir

“…The investigation of surging glaciers using satellite data received recently increased attention among scientists, in particular for the Karakoram mountain range but also other regions of the world (Berthier and Brun, 2019;Bhambri et al, 2017;Bolch et al, 2017;Falaschi et al, 2018;Minora et al, 2016;Paul, 2015;Quincey et al, 2015;Rankl and Braun, 2016;Round et al, 2017;Steiner et al, 2018). This has several reasons, for example (a) the free access to long (Landsat) and dense (TerraSAR-X / TanDEM-X, Sentinel-1/2) time series of highresolution satellite data, (b) the limited understanding of why some glaciers in this region are surging while others do not, (c) a high amount of on-going surges at any point in time, (d) the large variations of surge behaviour in a small region, (e) the long history and still occurring surge-related hazards (mostly due to damming of a river and related outburst of lakes), and (f) the very difficult field access.…”