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Climate change is causing glaciers in the Himalayas to recede and shrink. The changing climate is the primary trigger of the expansion of glacial lakes that increases the possibilities of outburst floods (GLOFs) and leads to quantifiable losses such as mortality and damage to populations and infrastructure downstream. Therefore, determining the hazard related to the glacier lakes of the Himalayan region is essential. We have developed an approach named SHIVEK, consisting of the SWIR band thresholding technique and hazard analysis to estimate the possible downstream risk along the GLOF flow path. We examined the spatiotemporal expansion of Imja Lake from 1997 to 2020 using Landsat 5, 7, and 8 data. We employed an automated form of the previously described method based on SWIR band thresholding. The study creates yearly composites from June to September using pre-processed Landsat imageries using a cloud-based platform Google Earth Engine. Our results show a continuous expansion in the geographical area of Imja Lake from 0.81 to 1.56 km2 in 23 years between 1997 and 2020, averaging nearly 0.032 km2 per year. Also, the lake's area between 2012 and 2020 expanded by 0.26 km2. The overall accuracy of 88.96 ± 6.93% has been achieved for spatiotemporal maps of Imja Lake and intensified confidence in the approach. This study estimates a total of 645 buildings and four bridges that can be impacted due to the outburst of Imja Lake. [ABSTRACT FROM AUTHOR]

Glacial retreat causes the formation of glacier lakes with the potential of producing glacial lake outburst floods (GLOFs). Imja Lake in Nepal is considered at risk for a GLOF. Communities in the path of a potential Imja GLOF are implementing adaptation projects, yet no quantitative data or guidance is available to understand the benefits of these projects or how to weigh benefits against the cost of implementation. We develop and demonstrate a decision-making methodology for GLOF risk management, incorporating available scientific information and uncertainty. The methodology consists of (1) identifying flooding scenarios, (2) evaluating scenario consequences, and (3) performing an economic analysis of proposed adaptation projects. The methodology is applied to assess benefits in Dingboche of lowering Imja Lake by 3, 10 and 20 m. The results show that the baseline case (no lake lowering) has the lowest expected cost because of low valuation of agricultural land and homes in the literature. Nonetheless, the result is sensitive to changes in the analysis variables. We also found that lowering the lake by 10 or 20 m is efficient according only to the methodology used here; however, considering only direct economic damages and literature cost estimates, the costs outweigh the benefits for these projects. [ABSTRACT FROM AUTHOR]

Glacial retreat causes the formation of glacier lakes with the potential of producing glacial lake outburst floods (GLOFs). Imja Lake in Nepal is considered at risk for a GLOF. Communities in the path of a potential Imja GLOF are implementing adaptation projects, yet no quantitative data or guidance is available to understand the benefits of these projects or how to weigh benefits against the cost of implementation. We develop and demonstrate a decision-making methodology for GLOF risk management, incorporating available scientific information and uncertainty. The methodology consists of (1) identifying flooding scenarios, (2) evaluating scenario consequences, and (3) performing an economic analysis of proposed adaptation projects. The methodology is applied to assess benefits in Dingboche of lowering Imja Lake by 3, 10 and 20 m. The results show that the baseline case (no lake lowering) has the lowest expected cost because of low valuation of agricultural land and homes in the literature. Nonetheless, the result is sensitive to changes in the analysis variables. We also found that lowering the lake by 10 or 20 m is efficient according only to the methodology used here; however, considering only direct economic damages and literature cost estimates, the costs outweigh the benefits for these projects.