Lemthang Tsho glacial Lake outburst flood (GLOF) in Bhutan: cause and impact

Abstract

Background: The Hindu Kush Himalayan (HKH) region being seismically active and sensitive to climate change is prone to glacial lake outburst flood (GLOF). The Lemthang Tsho GLOF breached in the evening of 28 July 2015 innorth-western Bhutan is reminds of the looming threat, and stresses the need to have good risk management plan. The need to understand the physical processes in generating GLOF to is therefore imperative in order to effectively manage the associated risk. The paper therefore assesses the cause and impact of the Lemthang Tsho GLOF event using field and remote sensing data. Results: The collapse of near vertical wall of supraglacial lake triggered by 2 days of incessant rainfall, opened up the englacial conduit resulting in emptying of interconnected supraglacial lakes into Lemthang Tsho. The5.1 magnitude earthquake epicentered 187 km to southeast in the Indian state of Assam in the morning (7:10 am Bhutan Standard Time) of the same day is unlikely to have played any role in triggering the event. The estimated volume of water unleased is 0.37 million m

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

“…As shown in Table 2, the ratios of Lc to Ld of nos. 13,20,33,35,36, and 42 are larger than 1.0; this indicates that the possible GLOFs of these six lakes may endanger the dam. Additionally, the upper limit line can be described as L = 0.52V + 59.…”

“…Since 1935, 62 glacial lake outburst flood (GLOF) events initiated from 56 glacial lakes in the Himalayas have been recorded, of which 8 occurred in Nepal [1], and the frequency has reached 1 event every 3-10 years [2][3][4]. This area has experienced many GLOFs in the past, of which the Cirenmaco GLOF (11 July 1981) located in the Sun Koshi River Basin in China [1,[4][5][6][7], the Jinco GLOF (27 August 1982) at the headwaters of the Yairuzangbo River of the Pumqu Basin in China [4], the Dig Tsho (4 August 1985) [4,8,9] and Tam Pokhari (Sabai-Tsho) GLOFs (3 September 1998) [4,[10][11][12][13] in the Dudh Basin in Nepal, and the Jialongco GLOF (23 May and 29 June 2002) in the Poiqu Basin in China [14] are good examples of the destructive consequences of GLOF disasters in the Central Himalayas, resulting in the destruction of some of the major hydropower projects, further causing socioeconomic decline [4]. Therefore, before any hydroelectric plant is built in this GLOF-hazard-prone region, a GLOF risk analysis is of crucial importance [15].…”

The State of Remote Sensing Capabilities of Cascading Hazards Over High Mountain Asia

“…Glacier outburst floods refer to the sudden discharge of water from a glacier (Carrivick and Tweed, 2013), which can have runout distances of tens to hundreds of kilometers (Gunn, 1930;Hewitt, 1982;Vuichard and Zimmermann, 1987;Richardson and Reynolds, 2000;Reynolds, 2014;Gurung et al, 2017) and cause extensive geomorphic and socioeconomic damages. The flood water may be stored in a proglacial lake [often referred to as a glacial lake outburst flood (GLOF), e.g., Vuichard and Zimmermann, 1987], within the glaciers' subsurface (e.g., Rounce et al, 2017a), or behind an ice dam (e.g., Round et al, 2017).…”

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

“…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). Many studies also assess the socioeconomic losses emanating from past and potential future GLOF events in these countries (Cuellar and McKinney 2017;Gurung et al 2017;Khanal et al 2015).…”