Temporal and spatial changes of glacial lakes in the central Himalayas and their response to climate change based on multi-source remote sensing data

Abstract

Global warming has significantly accelerated the retreat of glaciers and expansion of glacial lakes in the central Himalayas, thereby heightening the risks of various disasters, including ice avalanches, rock avalanches, and glacial lake outburst floods (GLOFs). These events pose considerable threats to the lives and properties of individuals residing in downstream areas. Consequently, conducting comprehensive research into the geographical distribution, formation, and evolutionary processes of glacial lakes, along with assessments of the potential impacts of GLOFs on climate change, is critically important for developing strategies to mitigate associated risks. To address this need, we propose a dynamic threshold method (known as OTSU) to facilitate the automatic and precise extraction of glacial lake boundaries in the central Himalayas. This innovative approach leverages the enhanced normalized difference water index (ENDWI), derived from multi-temporal Landsat series remote sensing imagery and Sentinel-2A /2B datasets, which were sourced from the Google Earth Engine (GEE) platform for the years 1990–2022. In addition to extracting lake boundaries, we examined the spatiotemporal evolution characteristics of glacial lakes in the region. Moreover, mathematical statistics were employed to systematically organize and analyse the GLOF disaster events in the central Himalayas. Finally, thoroughly investigate the interplay between glacial lake evolution and climate change, we incorporated relevant meteorological data. The present findings reveal that: 1) Glacial lakes are primarily distributed in the border area between China and Nepal in the central Himalayas, composed of non-contact lakes with glaciers, and concentrated in the altitude range of 3600–5900 m. 2) Since the 1990s, the expansion of glacial lakes is predominated by small glacial lakes in the central Himalayas; there have been 847 new glacial lakes, and the area and volume of glacial lakes has increased by 88.61 ± 4.64 km2 and 24.72 ± 2.59 km3, respectively. 3) Global warming, coupled with the escalating rates of glacial meltwater, serves as the primary catalyst for the proliferation of glacial lakes. This multifaceted approach aims to provide a clearer understanding of the dynamics at play in this vulnerable region and to inform effective risk management strategies. Since 1950, there has been a significant increase in the frequency of GLOFs, with the month of June demonstrating the highest incidence, followed closely by August. These glacial lake outbursts are predominantly instigated by ice avalanches. The present findings provide valuable scientific insights that could contribute to the mitigation of regional natural disasters.