Glacial Lake Changes and Identification of Potentially Dangerous Glacial Lakes in the Yi’ong Zangbo River Basin

Abstract

The southeastern Tibetan Plateau, where monsoonal temperate glaciers are most developed, has a huge number of glacial lakes. Based on Landsat Operational Land Imager (OLI) images, 192 glacial lakes with a total area of 45.73 ± 6.18 km2 in 2016 were delineated in the Yi’ong Zangbo River Basin. Glacial lakes with areas of less than 0.1 km2 accounted for 81.77% of the total number, and glacial lakes located above 4500 m elevation comprised 83.33%. Dramatic glacier melting caused by climate warming has occurred, resulting in the formation and expansion of glacial lakes and the increase of potential glacial lake outburst floods (GLOFs) risk. From 1970 to 2016, the total area of glaciers in the basin has decreased by 35.39%, whereas the number and total area of glacial lakes have, respectively, increased by 86 and 1.59 km2. In that time, 110 new glacial lakes emerged, whereas 24 of the original lakes disappeared. The newly formed lakes have a smaller mean area but higher mean elevation than the lakes that disappeared. Based on five indicators, a first-order method was used to identify glacial lakes that pose potential threats. We identified 10 lakes with very high, 7 with high, 31 with medium, and 19 with low GLOF susceptibility, out of 67 moraine-dammed glacial lakes with areas larger than 0.02 km2. Understanding the behavior of glaciers and glacial lakes is a vital aspect of GLOFs disaster management, and the monitoring of glacial lakes should be strengthened.

Glacial Lake Outburst Floods Simulation in the Yi’ong Zangbo River Basin Based on One-Dimensional Hydrodynamic Model

“…The Jionglaco is directly connect to its mother glacier, which has retreat rapidly in company with the lake expansion. It has an intact lake basin topography and the average height difference between water level and dam is only 5 m. Therefore, the Jionglaco was identi ed as a potentially hazardous glacial lake by Duan et al (2020) and Wang et al (2020). However, the dam of the Jionglaco is very at and a natural outlet of 40 m in width has formed, which is a favorable condition for maintaining the water balance of the glacial lake and reduces the impact of hydrostatic pressure on the dam.…”

“…However, the occurrence of GLOFs cannot be ruled out in extreme cases due to the injection of large volumes of water, which may be caused by the large increased meltwater from mother glacier due to abnormally high temperatures, extensive basin in ow due to extreme precipitation and in ow from other GLOFs. A high-risk glacial lake, Jiongpuco is located to the southwest of the Jionglaco, which has also undergone an area expansion in the past 20 years (Duan et al 2020;Wang et al 2020). Jiongpuco's out ow directly injects into the Jionglaco, therefore the hypothetical GLOF of Jiongpuco will probably produce a large disturbance to the Jionglaco, thus triggering the occurrence of GLOF in the Jionglaco.…”

Identification of Hazardous Glacial Lakes in the Yarlung Zangbo River Basin Based on Lakes Changes Determined Using Google Earth Engine

“…Glacial lakes are natural water bodies where either the main recharge source is modern glacial melt water or water accumulated in a moraine dam depression (Qin et al, 2014;Yao et al, 2018). The formation and development of glacial lakes are an indicator of climate change (Richardson and Reynolds, 2000;Gardelle et al, 2011;Khanal et al, 2015;Emmer et al, 2016;Duan et al, 2020). The glacial lake are important globally and regionally (Wilson et al, 2018) as a considerable water resource (Haeberli et al, 2016).…”

“…Current studies on glacial lakes on the Tibetan Plateau and its surrounding areas mainly include the distribution and variation of glacial lakes (Nie et al, 2013;Nie et al, 2017;Duan et al, 2020), the causes of changes to glacial lakes (Xin Nie et al, 2017), the identification of potential high risk glacial lakes (Weicai Liu et al, 2019;Duan et al, 2020), and analysis of typical glacial lake outburst mechanisms (Sun et al, 2014;Nie et al, 2020). Glacial lakes are strongly dependent on season; therefore accurate mapping requires images from the same season, preferably autumn (Xie et al, 2013).…”

“…At present, research on glacial lakes in the YZRB has mainly focused on the eastern region where the concentration of glaciers is highest (Liu et al, 2019;Duan et al, 2020;Qi et al, 2020). However, the type of glacier and the climate change characteristics in the eastern YZRB are very different to the western YZRB.…”