October 27, 2011

Milam Glacier Retreat, India

Posted by Mauri Pelto

Milam Glacier flows south from the summit of Trisul in the Indian Himalaya. The glacier is fed by a number of tributaries flowing off the north ridge of Nanda Devi as well. A recent paper by Raj (2011) documents the retreat of this glacier from 1954-2006. In the October 16, 2011 satellite image below, the snowline is at 5100 meters (black arrows) and the terminus at 3600 meters (red arrow). The accumulation zone stretches from the icefall regions at 5000-5200 meters to near the summit of Trisul at 7000 meters. From 1954-1976 Milam Glacier retreated at 20 Meters/year, 440 m. From 1976 to 1990 retreat was still 20 meters/year, 290 m. From 1990-2006 the glacier retreated 40 meters/year, 600 meters. The image below is from the Raj (2011) paper. Raj et al (2014) note that the glacier has retreated 480 m from 2004-2011 an acceleration. They further note an increase in the number of ponds and their size on the glacier, with the growth of 47 notable ponds on the glacier surface (Note their Figure 3, below). The Milam Glacier feeds the Gori Ganga River where a 370 MW hydropower system is anticipated to be built, the system will be a run of the river hydro project. A closeup view from Google Earth imagery of the terminus indicates its stagnant nature and the location of the glacier outlet stream emerging from the under the glacier is a good marker of the terminus, note arrow in top image below. A comparison of 2004 (middle) and 2009 (bottom) indicate the stagnant debris covered nature of the glacier terminus area. A new lake has developed upglacier of the terminus at Point A after 2004. The lake beyond the terminus at Point C has expanded. The terminus where the stream issues from under the glacier is at Point B. milam glacier raj 2011
Fuigure 3 from the Raj et al (2014) in Journal of Geological Society of India. The glacier is fed by a number of tributaries that now barely reach and contribute little in the way of volume to the Milam Glacier. These are labelled in the base map from Raj (2011). A closeup example is the Pachmi Drachnu Glacier. The red arrow points out the lateral moraine that now is 100 meters above the current Milam and Pachmi Drachnu Glacier surface. The blue arrow indicates the meager ice supply reaching the Milam Glacier . The Milam Glacier is a summer accumulation type glacier receiving the bulk of its melt and accumulation during the summer monsoon season. This type of glacier is not sensitive to black carbon ablation enhancement as the lower section is debris covered and the upper section covered by frequent new summer snowfall. The retreat of this glacier is similar to that of neighboring glaciers such as the Parbati Glacier, Gangotri Glacier and Satopanth Glacier