Prof. Sunil Kumar De 
Department of Geography, North-Eastern Hill University, India
Shillong and President, International Association of Geomorphologists (IAG) 

Area of Interest: 
Environmental Geomorphology; Geomorphological Hazards specially Landslide, Soil Erosion and Fluvial Hazards; River Health

Presentation topic: 
A Study on Assessing Climate-Driven Glacial Lake Hazards in the Sikkim Himalaya, India​

The Sikkim Himalaya has undergone significant glacial retreat due to the impacts of climate change, resulting in the rapid expansion of glacier-fed lakes. This growing trend raises concerns over the increased risk of glacial lake outbursts, which pose serious threats to downstream populations. This study focuses on the Chhombo Chhu watershed within the Tista basin, a region characterized by numerous large glacial lakes, situated between the Greater Himalayan Morphometric zone and the Tethyan Sedimentary Sequence. Through the analysis of medium- to high-resolution optical satellite imagery from 1975, 1989, 2000, 2010, and 2018, combined with extensive field surveys, the research documents a sharp increase in the number of glacial lakes, rising from 62 to 98. The total area of these lakes has expanded by 34.6 ± 5.4%, growing from 8.5 ± 0.2 km2 in 1975 to 11.4 ± 0.6 km2 in 2018. Notably, the rate of expansion accelerated between 2010 and 2018, highlighting an intensification of landscape changes in recent years. A hazard assessment identified twenty-seven lakes in the watershed with varying degrees of outburst potential. The increasing trend in long-term annual temperatures (0.283°C a–1 from 1975 to 2013) closely correlates with both the retreat of glaciers (–0.66 ± 0.1% a–1) and the expansion of glacial lakes (+0.80 ± 0.1% a–1) from 1975 to 2018. These findings emphasize the significant role of climate change in reshaping glacial lake dynamics and the associated hazard risks in the Sikkim Himalaya.