Melting Himalayan Glaciers Threaten Domestic Water Resources in the Mount Everest Region, Nepal

Leah R Wood,Subodh Sharma,Broxton W Bird,Kirsten N Nicholson,Carolyn B Dowling,Klaus Neumann

doi:10.3389/feart.2020.00128

Abstract

Retreating glaciers and snowpack loss threaten high-altitude communities that rely upon seasonal melt for domestic water resources. But the extent to which such communities are vulnerable is not yet understood, largely because melt contribution to water supplies is rarely quantified at the catchment scale. The Khumbu Valley, Nepal is a highly glaciated catchment with elevations ranging from 2000-8848 m above sea level, where more than 80% of annual precipitation falls during the summer monsoon from June to September. Samples were collected from the rivers, tributaries, springs, and taps along the major trekking route between Lukla and Everest Base Camp in the premonsoon seasons of 2016-2017. Sources were chosen based upon their use by the communities for drinking, cooking, bathing and washing, so the sample suite is representative of the local domestic water supply. In addition, meltwater samples were collected directly from the base of the Khumbu Glacier, and several rain samples were collected throughout the study site. Meltwater contribution was estimated from d 18 O isotopic data using a two-component mixing model with the Khumbu glacial melt and pre-monsoon rain as endmembers. Results indicate between 34-90% of water comes from melt during the dry, pre-monsoon season, with an average meltwater contribution of 65%. With as much as two-thirds of the dry-season domestic water supply at risk, the communities of the Khumbu Valley are extremely vulnerable to the effects of climate change as glaciers retreat and snowpack declines.

Highlights

High-elevation communities are some of the most susceptible to the effects of climate change (Salerno et al, 2008), and a recent report concluded that even if global warming is kept below 1.5◦C, a third of the glaciers in the Hindu Kush-Himalayan region and more than half of those in the eastern Himalaya will likely be lost by the end of this century (Bolch et al, 2019)
(1) Domestic water resources in the Khumbu Valley are of low ionic strength and are primarily of the calcium-bicarbonate water- type, and less commonly, calcium-sulfate, sodiumbicarbonate, and sodium-sulfate
(5) Water resources in the Khumbu Valley should continue to be monitored in future years to further confirm or to update the findings of this study with the ultimate goal of making the communities of the Khumbu Valley and other high-altitude communities more resilient in the face of climate change

Summary

Introduction

High-elevation communities are some of the most susceptible to the effects of climate change (Salerno et al, 2008), and a recent report concluded that even if global warming is kept below 1.5◦C, a third of the glaciers in the Hindu Kush-Himalayan region and more than half of those in the eastern Himalaya will likely be lost by the end of this century (Bolch et al, 2019). The Hindu Kush-Himalayan Region and Tibetan Plateau are often referred to as the Earth’s “Third Pole” (e.g., Yao et al, 2012) as they contain the greatest number of glaciers outside of polar regions. They are referred to as the “Water Tower of Asia” (e.g., Viviroli et al, 2007), because they are the headwaters for some of the continent’s largest rivers, including the Indus, Ganges, Brahmaputra, Yangtze, and Yellow rivers

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