Glacial Lake Outburst Flood Susceptibility Mapping in Sikkim: A Comparison of AHP and Fuzzy AHP Models

The Sikkim region of the Eastern Himalayas is highly susceptible to Glacial Lake Outburst
Floods (GLOFs), a risk that has increased significantly due to rapid glacial retreat driven by climate
change in recent years. This study presents a comprehensive evaluation of GLOF susceptibility in
Sikkim, employing Analytic Hierarchy Process (AHP) and Fuzzy Analytic Hierarchy Process
(FAHP) models. Key factors influencing GLOF vulnerability, including lake volume, seismic activity,
precipitation, slope, and proximity to rivers, were quantified to develop AHP and FAHP based
susceptibility maps. These maps were validated using Receiver Operating Characteristic (ROC)
curves, with the AHP method achieving an Area Under the Curve (AUC) of 0.92 and the FAHP
method scoring 0.88, indicating high predictive accuracy for both models. A comparison of the two
approaches revealed distinct characteristics, with FAHP providing more granular insights into moderate-
risk zones, while AHP offered stronger predictive capability for high-risk areas. Our results
indicated that the expansion of glacial lakes, particularly over the past three decades, has heightened
the potential for GLOFs, highlighting the urgent need for continuous monitoring and adaptive risk
mitigation strategies in the region. This study, in addition to enhancing our understanding of GLOF
risks in Sikkim, also provides a robust framework for assessing and managing these risks in other
glacial regions worldwide.