Abstract
ABSTRACTDespite previous studies, glacier–lake interactions and future lake development in the Poiqu River basin, central Himalaya, are still not well understood. We mapped glacial lakes, glaciers, their frontal positions and ice flow from optical remote sensing data, and calculated glacier surface elevation change from digital terrain models. During 1964–2017, the total glacial-lake area increased by ~110%. Glaciers retreated with an average rate of ~1.4 km2a−1between 1975 and 2015. Based on rapid area expansion (>150%), and information from previous studies, eight lakes were considered to be potentially dangerous glacial lakes. Corresponding lake-terminating glaciers showed an overall retreat of 6.0 ± 1.4 to 26.6 ± 1.1 m a−1and accompanying lake expansion. The regional mean glacier elevation change was −0.39 ± 0.13 m a−1while the glaciers associated with the eight potentially dangerous lakes lowered by −0.71 ± 0.05 m a−1from 1974 to 2017. The mean ice flow speed of these glaciers was ~10 m a−1from 2013 to 2017; about double the mean for the entire study area. Analysis of these data along with climate observations suggests that ice melting and calving processes play the dominant role in driving lake enlargement. Modelling of future lake development shows where new lakes might emerge and existing lakes could expand with projected glacial recession.
Highlights
There are more than 5000 glacial lakes in the Third Pole (a colloquial name given to the glaciated region of the Tibetan Plateau (TP) and surroundings), with the majority of these located in the Himalaya (Zhang and others, 2015; Nie and others, 2017)
The sudden release of water from lakes impounded by moraines or ice dams can result in glacial lake outburst floods (GLOFs), while more rarely, impact waves from large mass movement can cause overtopping from bedrock dammed lakes
A GLOF risk assessment has been coordinated for the entire Hindu-Kush-Himalayan region (Ives and others, 2010), while national-scale assessments of critical glacial lakes have been conducted for the Indian Himalaya (Worni and others, 2013), the Nepal Himalaya (Rounce and others, 2017) and the Chinese Himalaya (Wang and others, 2012b, 2015)
Summary
There are more than 5000 glacial lakes (larger than 0.003 km2) in the Third Pole (a colloquial name given to the glaciated region of the Tibetan Plateau (TP) and surroundings), with the majority of these located in the Himalaya (Zhang and others, 2015; Nie and others, 2017). The glacial-lake area expanded by ∼14% between 1990 and 2015 in the whole Himalaya (Nie and others, 2017). Within the Himalaya located in Chinese territory, glacial-lake area increased by ∼30% between the 1970s and the 2000s (Wang and others, 2012a). These increases were due to the formation and development of glacial lakes, especially proglacial lakes, emerging and expanding as glaciers retreated (Benn and others, 2012; Zhang and others, 2015; Nie and others, 2017). A GLOF risk assessment has been coordinated for the entire Hindu-Kush-Himalayan region (Ives and others, 2010), while national-scale assessments of critical glacial lakes have been conducted for the Indian Himalaya (Worni and others, 2013), the Nepal Himalaya (Rounce and others, 2017) and the Chinese Himalaya (Wang and others, 2012b, 2015). 80% of GLOFs in the Himalaya were initiated by displacement waves from ice avalanches (Awal and others, 2010)
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