June 27, 2016
Comparison of Suatisi Vost (SV) and Suatisi Sredny (SS) in 1986 and 2015 Landsat images. The red arrow is the 1986 terminus and the yellow arrows the 2015 terminus. Point A and B are to areas of expanding bedrock amidst the glacier.
Suatisi Vost and Suatisi Sredny Glacier are two glaciers on the south flank of Mount Kazbek in northern Georgia. The region is prone to landslides and debris flows. On September 20, 2002 a collapse of a hanging glacier from the slope of Mt Dzhimarai-Khokh onto the Kolka glacier triggered an avalanche of ice and debris that went over the Maili Glacier terminus then slid over 15 miles (NASA Earth Observatory, 2002). It buried small villages in the Russian Republic of North Ossetia, killing dozens of people. The glacier runoff from Suatisi Glacier supplies the Terek River, which has a hydropower project under construction. The Dariali Hydroplant will have an installed capacity of 108 MW and is a run of river type plant near Stepantsminda, Georgia. This plant has suffered from two landslides in 2014 (Glacier Hub, 2014) that jeopardize its completion.
Shagadenova et al (2014) examined glaciers in the Caucasus mountains and found that from 1999/2001 and 2010/2012 total glacier area decreased by 4.7%. They also noted that recession rates of valley glacier termini increased between 1987– 2000 and 2001–2010, with the latter period featuring retreats averaging over 10 m/year. A positive trend in summer temperatures forced glacier recession (Shagadenova et al 2014). Here we examine changes in Suatisi Glacier from 1986 to 2015 with Landsat imagery.
In 1986 Suatisi Vost western side terminates at the top of deep canyon, red arrow. The eastern side of the terminus is on a flatter till plain. The area around Point B is all glacier ice. Suastisi Sredny terminates near the end of the valley it occupies in 1986. In the 2001 image a large debris flow/landslide has covered the eastern margin of Suatisi Vost surrounding the area of Point B, black arrow in 2001 image below. By 2010 the Google Earth image indicates significant retreat of Suatisi Vost and the debris flow below point B is a light gray color. The bedrock at Point B has expanded. By 2015 Suatisi Vost terminus has retreated 350 m since 1986, what is just as evident is the loss in width of the terminus in the 1986-2015 side by side comparison. Suatisi Sredny has retreated 450 m. The snowline is at an elevation of 3750-3800 m in 1986, 2010 and 2015. With the terminus at 3250 m and the highest elevation at 3950-4000 m, this is too high to sustain the glacier at its current size and retreat will continue. The debris cover has reached the terminus on the east side of the glacier by 2015. The changes are the same across the border in Russia, for example Lednik Midagrabin.
2010 Google Earth image of Suatisi Vost and Suatisi Sredny.
2001 Landsat image indicating the landslide covering surface of Suatisi Vost.
2015 Landsat image indicates Landslide deposit evolution, with movement downglacier and retreat, it is now close to the ice front on the east side of the margin.