An Estimated Contribution of Glacier Runoff to Mongolia's Upper Khovd River Basin in the Altai Mountains

Caleb G. Pan,Munkhdavaa Munkhjargal,Ulrich Kamp,Avirmed Dashtseren,Sarah J. Halvorson,Michael Walther

doi:10.1659/mrd-journal-d-18-00059.1

Abstract

In the semiarid climate of northwestern Mongolia, glaciers are critical contributors to water resources, particularly during the dry summer months. Nevertheless, our knowledge of the contribution of glacier runoff in the Upper Khovd River Basin (UKRB) is limited. This study investigates the impact of glacier recession on the UKRB's hydrology in western Mongolia's Altai Mountains. The analysis included glaciological method measurements, satellite-derived glacier extent records, and a simple ice ablation model. Our modeling used a mass balance gradient of 0.50 meters water equivalent 100 m–1 for the years 2000, 2010, and 2016 and included a sensitivity analysis that applied lower and upper mass balance gradient values and ±200 m around the equilibrium line altitude (ELA). The glacier contribution to the UKRB's water resources decreased from almost 8% in 2000 to 6.7% in 2016. Hypsometries revealed that glacier areas decreased at all elevations, indicating that only small accumulation zones exist. Therefore, applying a modeled increased ELA better represents glacier contribution to total runoff, at 18.7% in 2000 and 15.4% in 2016. The decreasing glacier runoff contribution indicates that the UKRB glaciers have passed the tipping point of an increased contribution that first follows enhanced melting. The continued glacier recession and uncertain water availability represent challenges for water resource management and future human–water relations in the Mongolian Altai.

Highlights

The Altai Mountains of Mongolia are uniquely positioned in an extreme continental climate that governs a semiarid to arid landscape
Hydrographic data provide a qualitative assessment in the relative contribution of glaciers to streamflow
The determination of the contribution of glaciers to the Upper Khovd River Basin (UKRB)’s hydrology is a key step forward in creating adaptations and building resilience within an environment and culture that is vulnerable to slight environmental fluxes

Summary

Introduction

The Altai Mountains of Mongolia are uniquely positioned in an extreme continental climate that governs a semiarid to arid landscape. Arid mountainous landscapes of the Altai and elsewhere in Central Asia are limited by the availability of water, naturally reflected in the dry-tolerant grass and scrublands that dominate the region (Li et al 2015). Water insecurity and related vulnerabilities are amplified through several mechanisms in Central Asia, such as agricultural consumption as a result of transitioning dry-tolerant vegetation for crops that require irrigation (Mosello 2008), the development of hydropower plants (HPPs) as a solution to increasing energy demand and as regulators of downstream water flows (Gaudard et al 2014), and continued amplified warming (Chen et al 2009) coupled with decreasing precipitation (Batima 2005). As accelerated glacier recession continues in the 21st century with amplified warming (Zemp et al 2015), understanding the role of glacier runoff in water availability has become urgent and has received

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