Nasir Hussain | Research Officer, WAPDA
Karakoram is the most heavily glacierized mountain range in Asia, comprising one fourth of the glaciers in the Himalaya-Karakoram-Hindukush (HKH) region. The concentration of surge-type glaciers in the Karakoram is among the highest on Earth. Karakoram glaciers surges have been reported since the early nineteenth century. A recent investigation identified 223 surge-type and surge-like glaciers in the Karakoram.
Shishper glacier is also situated in Western Karakorum at Hassanabad, Hunza. It is 12kms long and covers an area of almost 24.9 km2 , originating from Shishper peak. Last month, the glacier advanced and caused a destructive flooding of the downstream valley.
The present terminus advance of Shisper glacier was modest compared to past advances of 9.3 km and 9.8 km, for the 1892-93 and 1903 surges, respectively. Shisper glacier has one half of a previously much larger glacier tongue, separated into two after 1950. The glacier has a history of surging and retreating, some very well documented in colonial chronicles.
It is estimated that, globally, temperature has increased 0.3-0.60 C over the past 100 years due to global warming which has enhanced melting rate of glaciers in the HKH region also, and as a result glaciers are retreating and lakes are getting formed. However, in the Karakorum region some glaciers, like Mastung and Turkestan type glaciers, show different behavior like surge or remain stable, a phenomena also called the Karakorum Anamoly. Surges can either be thermally, hydrologically and precipitations etc. Meanwhile, Apline type glaciers in the same region have been retreating.
Shishper glacier advanced 1.78 km in June 2018. The glacier hit the opposite flank of the mountain and blocked the passage of glacier and snow melt flow from Machuhar glacier that resulted in the formation of an Ice-dammed lake in November 2018. The ice-dammed lakes posed downstream outburst hazards and threatens the downstream communities, infrastructure, and livelihood. Such lakes may burst multiple times until the ice dam created by the surge melts away.
While many glacier surges occur without any further discernible consequences for downstream populations, a number of surges have been associated with potentially dangerous lakes and associated hazards specifically in the Karakoram region.
In case of surge in Shisper glacier, ice dammed lakes were created since 2018 and the Glacial Lake Outbust Flood (GLOF) triggered in June 2019, and then again in May 2020, 2021 and 2022.
In late Autumn of 2018, formation of lake started at the right bank of surged Shishper glacier and bursted in June 2019. Furthermore in 2019 (late autumn), when temperature in high elevation started to decline, the resultant englacial tunnel/pathway started to freez/close and this again started the formation of an ice-dammed lake. This process of formation of lakes and consequent GlOFs has occured repeatly since 2018.
The GMRC WAPDA team has been monitoring the physical behavior of the glacier and the ice-dammed lake formation since July 2020. The GMRC glacier experts built benchmarks in July 2020 at the Left and Right Banks of Shisper glacier and again visited the same site in April 2022.
The GLOF events have been caused devastations in downstream population since 2019. The major destruction caused in May 2022 by GLOF when an RCC Bridge, a sectio of the Karakoram -Highway (KKH), retaining walls, orchards, agriculture land, water courses and two power plants and seven local house were destroyed.
The water of Hassanabad Nullah (glacial stream) is the lifeline for three settlements of district Hunza, namely Aliabad, Murtazabad and Hassanabad. Therefore, it is necessary to mitigate the losses caused by the GLOF and to monitor lake and also conduct post disaster assessment survey to reduce further risk from ice dammed lake. A permanent solution is needed for the human settlement, otherwise every year the GLOF may hit the restored/rebuilt infrastructures and public property until Shishper glacier retreat back.
Nasir Hussain is a rResearch Officer/ Junior Earth Scientist at Glacier Monitoring & Research Center WAPDA Pakistan). He can be reached at email@example.com