January 4, 2012

Petrov Glacier Retreat, Kyrgyzstan

Posted by Mauri Pelto

Petrov Glacier flows north down the slopes of Ak-Shiyrak in the Tien Shan Mountains of Kyrgyzstan. The glacier ends in Petrov Lake which continues to expand as the glacier retreats. The glacier is 12 km long has three main tributaries each beginning at 4600-4700 meters and descending to the lake at 3700 meters. The lake in particular has been the focus of an extensive research project by a group Czech scientists, Cerny et al (2009) and Jansky et al (2009). This research for Geomin is driven by interest in a potential outburst flood event, the water level in the Petrov Lake and the moraine-ice dam are monitored and proposals on how to decrease the water level are being developed. Petrov Glacier is the largest glacier in the Naryn River watershed, Jansky et al (2009) report that the glacier retreated at a rate of 24 meters/year from 1957-1960, 40 meters/year from 1980-1999 and 61 m year from 1999-2006. Using two satellite images from 2001 (top) and 2011 (bottom) and Google Earth imagery from 2005 (middle) here we look in detail at the current condition of the glacier. The glacier has retreated 300 meters during the 2001-2011 period. Notice the Peninsula extending from the glacier into Petrov Lake (T).

2001 Landsat image

2005 Google Earth image

2011 Landsat image

A snapshot of the glacier at three different locations indicate the extent of the ablation zone. For points A,B and C the red arrow indicates lateral moraines, green arrows surface wind scour features that have trapped dust, and the blue arrows surface streams. Lateral moraines and surface streams cannot exist in the accumulation zone, and the wind scour features indicate locations where accumulation is not retained. Each of these feature types at A,B and C extend to 4300 meters. A glacier such as Petrov that lacks substantial avalanching and is in a region of low annual precipitation generally needs 60% of its area in the accumulation zone to be in equilibrium. The glacier has insufficient accumulation zone size recently and will have to continue to retreat. Petrov Glacier reflects the trends of the region where glaciers have lost 2 cubic kilometers per year of volume from 1955-2000, as documented by Harrison and others, University of Newcastle