10. Current and Future Glacial Lake Outburst Flood Hazard: Application of GIS-Based Modeling in Himachal Pradesh, India

Most studies concerning the hazard from glacial lake outburst floods have focused on the threat from lakes that have formed over the past century, some of which have demonstrated significant growth in response to recent warming of the climate system. However, attention is shifting toward the anticipation of future hazard and risk associated with new lakes that will develop as glaciers continue to retreat and water accumulates within depressions in the exposed bed topography. Using the Indian Himalayan state of Himachal Pradesh as a case study, this chapter provides both a review and implementation of modern approaches to assess current and future glacier lake outburst flood hazard over large spatial scales. Across Himachal Pradesh, the formation of new lakes over the next decades will lead to a minimum two- to threefold increase in land area affected by potential lake outburst floods in several districts. Generally the potential increase in glacial lake outburst flood frequency is demonstrated to be even greater, owing to the heightened opportunity for ice or rock avalanches to impact into larger and more numerous glacial lakes. Methods described herein allow early anticipation of future threats, providing a scientific basis for sound adaptation and planning responses.