Evolution and outburst risk analysis of moraine-dammed lakes in the central Chinese Himalaya

Abstract

The recent evolution and outburst risk of two typical moraine-dammed lakes, Galong and Gangxi, central Chinese Himalaya, are analyzed using topographic maps from 1974 and Landsat satellite imagery acquired in 1988, 2000 and 2014. The datasets show the areas of Galong and Gangxi lakes increasing at rates of 0.45 and 0.34 km 2 /year during the period 1974-2014, an expansion of 501% and 107%, respectively, in the past 41 years, while the areas of the parent glaciers, Reqiang and Jipucong decreased by 44.22% and 37.76%, respectively. The accelerating retreat of the glaciers not only reflects their generally negative mass balance but is consistent with the rapid expansion of the moraine-dammed lakes. When acted upon by external forces such as earthquakes, heavy rainfall, rapid melting of glaciers and dead ice, and snow/ice/rock avalanches, these lakes can become extremely dangerous, easily forming outburst mudslides, which can potentially spread to the Poiqu river basin and develop into cross-border (China and Nepal) GLOF disasters. Therefore, there is an urgent need to strengthen integrated risk management of glacial lake outburst disasters with multiple objectives and modes.

Glacial lake evolution and glacier–lake interactions in the Poiqu River basin, central Himalaya, 1964–2017

“…A comparison of topographic maps from 1974 and Landsat imagery for 2014 reveals that Galongco and Gangxico lakes expanded by ~500% (0.45 km 2 a −1 ) and ~107% (0.34 km 2 a −1 ) respectively over this period. This expansion corresponds to an area shrinkage of their parent glaciers of Jipucong and Reqiang of ~40% (~0.07 km 2 a −1 ) (Wang and Jiao, 2015). Seven lakes, including Galonco, Gangxico, Youmojianco and Cirenmaco in the basin have previously been identified as PDGLs based on high rates of expansion and a semiquantitative method considering other factors relevant for lake stability (Chen and others, 2007a; Wang and others, 2014).…”

“…1). Previous studies identified the high level of risk in this basin, as the potential for GLOF hazards is high and any outburst could severely affect livelihoods and infrastructure (Khanal and others, 2015; Wang and others, 2015). This basin also has the highest ratio of glacier area to lake area in the Hindu-Kush-Karakoram-Himalaya (HKH) regions (Wang and others, 2014).…”

“…The Himalayas are one of the mountain regions of the world where GLOFs occur most frequently (Carrivick and Tweed, 2016). 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). Moraine-dammed lakes are more common in the central and eastern Himalayas, while ice-dammed lakes predominate in the western regions (Richardson and Reynolds, 2000).…”

“…Lake mapping based on Landsat images revealed 329 moraine-dammed lakes (⩾0.02 km 2 ) in the Chinese Himalaya with ~100 of them identified as potentially dangerous glacial lakes (PDGLs) (Wang and others, 2012b, 2015). Several of these lakes are located in the Poiqu River Basin.…”

Contributions of the cryosphere to mountain communities in the Hindu Kush Himalaya: a review

“…The vast majority of the case studies on cryosphere disservices are on glacial lake outburst floods (GLOFs), indicating their importance as a cause of great socioeconomic losses in the HKH (Iturrizaga 2005;Shijin and Shitai 2015) and in some instances far downstream (Allen et al 2016). Bhutan and Nepal have recently been recognized as the two countries facing the greatest economic consequences from GLOFs worldwide (Carrivick and Tweed 2016), including threats to the unique cultural heritage (Kropáček et al 2015;Sherry et al 2018).…”