Development of Supraglacial Ponds in the Everest Region, Nepal, between 1989 and 2018

Abstract

Several supraglacial ponds are developing and increasing in size and number in the Himalayan region. They are the precursors of large glacial lakes and may become potential for glacial lake outburst floods (GLOFs). Recently, GLOF events originating from supraglacial ponds were recorded; however, the spatial, temporal, and seasonal distributions of these ponds are not well documented. We chose 23 debris-covered glaciers in the Everest region, Nepal, to study the development of supraglacial ponds. We used historical Landsat images (30-m resolution) from 1989 to 2017, and Sentinel-2 (10-m resolution) images from 2016 to 2018 to understand the long-term development and seasonal variations of these ponds. We also used fine-resolution (0.5–2 m) WorldView and GeoEye imageries to reveal the high-resolution inventory of these features and these images were also used as references for accuracy assessments. We observed a continuous increase in the area and number of ponds from 1989–2017, with minor fluctuations. Similarly, seasonal variations were observed at the highest ponded area in the pre- and postmonsoon seasons, and lowest ponded area in the winter season. Substantial variations of the ponds were also observed among glaciers corresponding to their size, slope, width, moraine height, and elevation. The persistency and densities of the ponds with sizes >0.005 km2 were found near the glacier terminuses. Furthermore, spillway lakes on the Ngozompa, Bhote Koshi, Khumbu, and Lumsamba glaciers were expanding at a faster rate, indicating a trajectory towards large lake development. Our analysis also found that Sentinel-2 (10-m resolution) has good potential to study the seasonal changes of supraglacial ponds, while fine-resolution (<2 m) imagery is able to map the supraglacial ponds with high accuracy and can help in understanding the surrounding morphology of the glacier.

Upward Expansion of Supra-Glacial Debris Cover in the Hunza Valley, Karakoram, During 1990 ∼ 2019

“…Compared with clean ice or snow, the debris layer has a unique thermal process due to differences in physical properties such as reflectance, particle size, and color, which results in different ablation processes in the underlying ice (Østrem, 1959;Nicholson and Benn, 2006). Also, the differential ablation caused by an uneven distribution of debris thickness makes it easy for glaciers to form cliffs (Kindermann et al, 2008;Herreid and Pellicciotti, 2018) and ponds (Miles et al, 2016;Chand and Watanabe, 2019) in the ablation zone. Notably, these cliffs and ponds are not only factors that affect the hydrological process but also home to numerous glacial lakes, which can pose a serious threat to downstream communities and lead to catastrophic socioeconomic disasters in cases of glacial lake outburst flood (Benn et al, 2012;Dubey and Goyal, 2020).…”

Remote Sensing of Environmental Changes in Cold Regions: Methods, Achievements and Challenges

“…SW changes are also occurring in Arctic-boreal wetlands, lakes, rivers, and streams as permafrost degrades with regional climate warming [29,180,182]; surface subsidence during the initial stages of permafrost degradation leads to increased inundation, while later stages of permafrost thaw lead to surface drying and reduced wetland extent as drainage pathways increase [27]. The emerging glacier and thermokarst lakes formed as ice melts have a strong climate feedback and may increase regional hazards from outburst flooding [183,184].…”

Editorial for Special Issue: “Remote Sensing of Environmental Changes in Cold Regions”

“…The analyses showed a continuous increase in the area and number of supraglacial ponds from 1989-2017, consistent seasonal patterns and a great diversity of pond features. The satellite images also revealed high persistency and density of the ponds (>0.005 km 2 ) near the glacier terminuses; and a fast expanding of spillway lakes on the Ngozompa, Bhote Koshi, Khumbu and Lumsamba glaciers [7].…”