Cryosphere hazards in Ladakh: the 2014 Gya glacial lake outburst flood and its implications for risk assessment

Susanne Schmidt,Juliane Dame,Ravi Baghel,Marcus Nüsser

doi:10.1007/s11069-020-04262-8

Abstract

This article attempts to reconstruct the causes and consequences of the 2014 glacial lake outburst flood (GLOF) event in Gya, Ladakh. We analyse the evolution of the Gya glacial lake using a high temporal and high spatial resolution remote sensing approach. In order to frame the case study in a larger picture, we produce a comprehensive inventory of glacial lakes for the entire Trans-Himalayan region of Ladakh. Changes in the extent and number of glacial lakes have been detected for the years 1969, 1993, 2000/02 and 2018 in order to assess the potential risk of future GLOFs in the region. The remote sensing approach was supported by field surveys between 2014 and 2019. The case study of the Gya GLOF illustrates the problem of potentially hazardous lakes being overlooked in inventories. The broader analysis of the Ladakh region and in-depth analysis of one GLOF lead us to propose an integrated approach for detecting undocumented GLOFs. This article demonstrates the necessity for using multiple methods to ensure robustness of risk assessment. The improved understanding can lead to a more accurate evaluation of exposure to cryosphere hazards and identification of alternative mechanisms and spatial patterns of GLOFs in the Himalaya.

Highlights

Cryosphere dynamics and cryosphere-related hazards are a vital component of and threat for land use development in the semi-arid Trans-Himalayan region of Ladakh
The results are divided into two sections, the first on the glacial lake inventory for the entire Ladakh region and the second on the specific case of the Gya glacial lake outburst flood (GLOF) of 2014
A total of 192 glacial lakes cover an area of 5.93 ± 0.70 km2 with an estimated water volume of about 61.11 ± 8.5 million m3, including 127 proglacial (PG) and 9 supraglacial lakes and 56 lakes located on recent moraines (RM) in 2018 (Fig. 4)

Summary

Introduction

The observed and projected glacier decrease in the extended Himalayan region (Bolch et al 2019) and in Ladakh (Schmidt and Nüsser 2017) will affect livelihood security, both in the mountains and in the lowlands in the long run (Hock et al 2019; Huss and Hock 2018; Immerzeel et al 2010; Nüsser et al 2019). Glacial lake outburst floods (GLOFs) are major cryosphere hazards and a potential risk for local communities. On 6 August 2014, a glacial lake outburst flood (GLOF) hit the village of Gya (33° 39′ N, 77° 44′ E) in Ladakh. Large and recurrent GLOF events happened in the Shyok and Nubra valley, where the river was blocked by a glacier several times during the nineteenth century, followed by destructive outburst floods (Bhambri et al 2019, 2020; Cunningham 1854; Sheikh 2015; Sinclair 1929)

Results

Discussion

Conclusion