Recent Changes of Glacial Lakes in the High Mountain Asia and Its Potential Controlling Factors Analysis

Meimei Zhang,Ning Wang,Fang Chen,Hang Zhao,Jinxiao Wang

doi:10.3390/rs13183757

Abstract

The current glacial lake datasets in the High Mountain Asia (HMA) region still need to be improved because their boundary divisions in the land–water transition zone are not precisely delineate, and also some very small glacial lakes have been lost due to their mixed reflectance with backgrounds. In addition, most studies have only focused on the changes in the area of a glacial lake as a whole, but do not involve the actual changes of per pixel on its boundary and the potential controlling factors. In this research, we produced more accurate and complete maps of glacial lake extent in the HMA in 2008, 2012, and 2016 with consistent time intervals using Landsat satellite images and the Google Earth Engine (GEE) cloud computing platform, and further studied the formation, distribution, and dynamics of the glacial lakes. In total, 17,016 and 21,249 glacial lakes were detected in 2008 and 2016, respectively, covering an area of 1420.15 ± 232.76 km2 and 1577.38 ± 288.82 km2; the lakes were mainly located at altitudes between 4400 m and 5600 m. The annual areal expansion rate was approximately 1.38% from 2008 to 2016. To explore the cause of the rapid expansion of individual glacial lakes, we investigated their long-term expansion rates by measuring changes in shoreline positions. The results show that glacial lakes are expanding rapidly in areas close to glaciers and had a high expansion rate of larger than 20 m/yr from 2008 to 2016. Glacial lakes in the Himalayas showed the highest expansion rate of more than 2 m/yr, followed by the Karakoram Mountains (1.61 m/yr) and the Tianshan Mountains (1.52 m/yr). The accelerating rate of glacier ice and snow melting caused by global warming is the primary contributor to glacial lake growth. These results may provide information that will help in the understanding of detailed lake dynamics and the mechanism, and also facilitate the scientific recognition of the potential hazards associated with glacial lakes in this region.

Highlights

The High Mountain Asia (HMA), consisting mainly of the Tibetan Plateau (TP) and the surrounding mountains, has the largest volume of glaciers in the world outside the Arctic and Antarctic and is known as the Earth’s third pole [1,2]
The size and number of glacial lake systems have increased rapidly in recent years [7,8,9]. This glacier retreat has been accompanied by a growth in the population living close to the high mountains and potentially dangerous glacial lakes are emerging in the glaciated regions
This study provides an updated and complete outline of glacial lakes using an automated lake mapping method

Summary

Introduction

The High Mountain Asia (HMA), consisting mainly of the Tibetan Plateau (TP) and the surrounding mountains, has the largest volume of glaciers in the world outside the Arctic and Antarctic and is known as the Earth’s third pole [1,2]. In response to significant warming since the 1950s, more than half of the glaciers in the HMA have been found to be retreating [3,4,5,6]. The size and number of glacial lake systems have increased rapidly in recent years [7,8,9]. This glacier retreat has been accompanied by a growth in the population living close to the high mountains and potentially dangerous glacial lakes are emerging in the glaciated regions.

Objectives

Methods

Results

Discussion

Conclusion