GLOF Risk Assessment Model in the Himalayas: A Case Study of a Hydropower Project in the Upper Arun River

Abstract

A glacial lake outburst flood (GLOF) is a phenomenon that is widely known by researchers because such an event can wreak havoc on the natural environment as well as on manmade infrastructure. Therefore, a GLOF risk assessment is necessary, especially within river basins with hydropower plants, and may lead to a tremendous amount of socioeconomic loss if not done. However, due to the subjective and objective limitations of the available GLOF risk assessment methods, we have proposed a new and easily applied method with a wider application and without the need for adaptation changes in accordance with the subject area, which also allows for the repeated use of this model. In this study, we focused our efforts on the Upper Arun Hydroelectric Project (UAHEP) in the Arun River Basin, and we (1) identified 49 glacial lakes with areas greater than 0.1 km2; (2) geographically represented and analyzed these 49 glacial lakes for the period of 1990–2018; (3) analyzed the correlation between the temperature and precipitation trends and the occurrence of recorded GLOF events in the region; (4) proposed a new method based on the documented affected lengths and volumes derived from historical GLOF events to identify 4 potentially critical lakes; and (5) evaluated the discharge profiles using widely used empirical methods and further discussed the physical properties, triggering factors, and outburst probability of the critical lakes. To achieve these objectives, a series of intensive and integrated desk studies, data collections, and GLOF simulations and analyses were performed.

Reconstructing the History of Glacial Lake Outburst Floods (GLOF) in the Kanchenjunga Conservation Area, East Nepal: An Interdisciplinary Approach

“…As mentioned previously, most GLOFs are triggered by snow or ice/debris avalanches cascading into the lake, which in turn create surge waves capable of breaching the fragile terminal moraines which contain the lake water [4]. GLOFs are capable of causing enormous downstream damage to villages, agricultural land, and hydropower plants [64], and they too are expected to increase in frequency throughout the 2020s and into the 21st century [65]. Permafrost thaw is another triggering mechanism of growing concern [66], as it can catalyze destabilization of high-altitude rock/ice peaks, that in turn lead to major rockfall or landslide-induced avalanches.…”

Glacial Lake Outburst Flood Hazard and Risk Assessment of Gangabal Lake in the Upper Jhelum Basin of Kashmir Himalaya Using Geospatial Technology and Hydrodynamic Modeling

“…The lake has an area of 1.66 km 2 according to recent estimates (2020), which is greater than the threshold of 0.1 km 2 reported in past studies for categorizing the potentially dangerous glacial lake [31,[156][157][158][159]. The lake has expanded by 17% during the period 1972 to 2020.…”

Evolution and future prospects of hydropower sector in Nepal: A review

“…Over the last fifty years, there have been seven major GLOFs that damaged several hydropower projects. The Zhangzangbo GLOF (July 11, 1981) wreaked havoc on the Sun Koshi Hydropower Plant's diversion weir and other infrastructure, causing a total loss of over $3 million [ 55 ]. Also, on August 4, 1985, the Dig Tsho GLOF struck the Khumbu area and destroyed the Namche small hydropower station along a 42-km stretch, costing an estimated loss of US $1.5 million [ 56 ].…”

“…Also, on August 4, 1985, the Dig Tsho GLOF struck the Khumbu area and destroyed the Namche small hydropower station along a 42-km stretch, costing an estimated loss of US $1.5 million [ 56 ]. On August 2, 2014, a landslide occurred on the Sunkoshi River in Sindhupalchok District, Nepal, forming an artificial lake 47 m deep and 400 m long, which threatened downstream villages and the Lamisanghu Hydropower Dam [ 55 ].…”