Heterogeneous Expansion of End-moraine Dammed Lakes in the Hindukush-Karakoram-Himalaya Ranges of Pakistan during 2001-2013

Global climate change during the twentieth century had a significant impact on the glaciers that resulted in creation of new lakes and expansion of existing ones, and ultimately an increase in the number of glacial lake outburst floods (GLOFs) in the Himalayan region. This study reports variation of the end-moraine dammed lakes in the high altitude Hindukush-Karakoram-Himalaya (HKH) region of Pakistan to evaluate future floods hazard under changing climate in this region. An integrated temporal remote sensing and Geographic information system (GIS) based approach using satellite images of Landsat-7 and 8 was adopted to detect 482 end-moraine dammed lakes out of which 339 lakes (> 0.02 km²) were selected for temporal change analysis during the 2001-2013 period. The findings of the study revealed a net expansion in the end-moraine dammed lakes area in the Karakoram (about 7.7%) and in the Himalayas (4.6%), while there was a net shrinkage of about 1.5% in the lakes area in the Hindukush range during this period. The percentage increase in the lakes' area was highest above 4500 m asl in the Hindukush, within 3500-4000 m asl in the Himalayas and below 3500 m asl in the Karakoram range. The overall positive change in the lakes' area appears to prevail in various altitudinal ranges of the region. The heterogeneous areal changes in the end- moraine dammed lakes might be attributed to different climate regimes and glacial hydrodynamics in the three HKH ranges. A periodic monitoring of the glacial lakes and their associated glaciers is essential for developing effective hazard assessment and risk reduction strategies for this high altitude Himalayan region.