Identification of Potentially Dangerous Glacial Lakes (PDGLs) in the Northwest Himalayas

The retreat of glaciers has emerged as a significant threat in recent decades, leading to the emergence and growth of glacial lakes. Many of these lakes are vulnerable to Glacial Lake Outburst Floods (GLOFs) as a result of challenging geotectonic settings and adverse climatic environments. Satellite imageries, Digital Elevation Models (DEMs), seismic and meteorological data were utilized in this study to asses the vulnerability posed by more than 1300 glacial lakes in the Northwest Himalayas (NWH) to a potential GLOF event in the future. We employed the Analytic Hierarchy Processes (AHP) - Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) and AHP - Complex Proportional Assessment of Alternatives (COPRAS) approaches to identify Potentially Dangerous Glacial Lakes (PDGLs), using 15 key conditioning factors.  Over 20 lakes were identified as having very high risk to GLOFs, while more than 130 lakes were classified as being at a high risk. The upper Indus basin possessed the most number of vulnerable lakes, which are at a greater risk of experiencing a probable GLOF event, followed by the Jhelum basin. To authenticate our results, we examined the past GLOFs incidents and our analysis revealed that most of the previous GLOFs are classified as PDGLs falling into either the very high or high risk categories. The findings of this study will provide valuable insights for stakeholders and decision makers enabling them to implement preventive measures to mitigate risks during a potential GLOF event in future.