Evaluation of Glacial Lake Outburst Flood Susceptibility Using Multi-Criteria Assessment Framework in Mahalangur Himalaya

Nitesh Khadka,Guoxiong Zheng,Guoqing Zhang,Xiaoqing Chen,Yong Nie,Sudeep Thakuri

doi:10.3389/feart.2020.601288

Abstract

Ongoing recession of glaciers in the Himalaya in response to global climate change has far-reaching impacts on the formation and expansion of glacial lakes. The subsequent glacial lake outburst floods (GLOFs) are a significant threat to lives and livelihoods as they can cause catastrophic damage up to hundreds of kilometres downstream. Previous studies have reported the rapid expansion of glacial lakes and several notable destructive past GLOF events in the Mahalangur Himalaya, suggesting a necessity of timely and updated GLOF susceptibility assessment. Here, an updated inventory of glacial lakes across the Mahalangur Himalaya is developed based on 10-m Sentinel-2 satellite data from 2018. Additionally, the GLOF susceptibilities of glacial lakes (≥0.045 km2) are evaluated using a multi-criteria-based assessment framework where six key factors are selected and analyzed. Weight for each factor was assigned from the analytical hierarchy process. Glacial lakes are classified into very low, low, medium, high, and very high GLOF susceptibility classes depending upon their susceptibility index based on analysis of three historical GLOF events in the study area. The result shows the existence of 345 glacial lakes (&gt;0.001 km2) with a total area of 18.80 ± 1.35 km2 across the region in 2018. Furthermore, out of the 64 glacial lakes (≥0.045 km2) assessed, seven were identified with very high GLOF susceptibility. We underline that pronounced glacier-lake interaction will likely increase the GLOF susceptibility. Regular monitoring and more detailed fieldworks for these highly susceptible glacial lakes are necessary. This will benefit in early warning and disaster risk reduction of downstream communities.

Highlights

The Himalaya is characterized by a dense distribution of glacial lakes (Zhang et al, 2015; Maharjan et al, 2018), and they are rapidly expanding due to glaciers wasting in response to global climate change (Zhang et al, 2015; Nie et al, 2017)
This study was conducted in the Mahalangur section of the Himalaya to investigate the glacial lakes, and glacial lake outburst floods (GLOFs)
The multicriteria decision-based analytical hierarchy process was used to evaluate the degree of GLOF susceptibility from glacial lakes in the region discussing the several factors that regulate the probability of an outburst

Summary

Introduction

The Himalaya is characterized by a dense distribution of glacial lakes (Zhang et al, 2015; Maharjan et al, 2018), and they are rapidly expanding due to glaciers wasting in response to global climate change (Zhang et al, 2015; Nie et al, 2017). GLOF Susceptibility in Mahalangur Himalaya lakes which are disconnected, but lie in the periphery to the glacier and are fed by the glacier ice and snowmelt (Salerno et al, 2012; Otto, 2019). These glacial lakes display characteristic differences in terms of formation, dam structure, lifespan, expansion, emergence, disappearance and impact upon burst (Richardson and Reynolds, 2000; Mertes et al, 2017; Nie et al, 2017). The Himalayan region has been documented as a hot spot of GLOFs primarily from morainedammed glacial lakes with several historical GLOF records (Carrivick and Tweed, 2016; Nie et al, 2018; Veh et al, 2019)

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