Lekhziri Glacier, Georgia Retreat Leads to Separation 1996-2022

On December 20, 2022April 20, 2024 By mspeltoIn Caucasus Glacier retreat1 Comment

Lekhrziri Glacier in 1996 and 2022 Landsat images illustrating the retreat and separation of the three tributaries central (Lc), eastern (Le) and western (Lw). Red arrow indicates 1996 terminus and yellow arrows the 2022 terminus locations

Lekhrziri Glacier has been the largest glacier in Georgia, and was until 2011 a compound glacier comprised of three tributaries joining a short distance from the terminus (Tielidze et al 2016). Tielidze et al (2015) observed in 2011 that the central tributary separated from the east and west tributary that year at the headwaters of the Mestiachala River Basin. From 2000-2020 Lekhziri Glacier experienced the largest retreat, of 1395 m, of 16 large Caucasus glaciers examined by (Tielidze et al 2022). Here we examine Landsat and Sentinel imagery from 1996-2022 to illustrate the changing nature of this glacier.

In 1996 the three tributaries joined at 2300 m and then flowed jointly south for 1 km to the terminus, red arrow on Landsat image. The August snowline is at 3300 m. By 2013 the central glacier has visibly separated by 500 m from the other tributaries. The primary terminus has had a retreat of ~500 m since 1996. The August snowline is at 3400 m in 2013. In 2022 additional retreat as separated the east and west tributaries, with an evident river emanating from each tributary, yellow arrows, feeding into the Mestiachala River. The central tributary terminates 800 m from the former junction. The retreat of the east tributary has been 1.3 km since 1996 and the west tributary 1.25 km since 1996. There is also a small lake that is evident, green arrow, in 2022 that will fill in with sediment. The snowline at the end of August 2022 is at 3450 m. The persistent high snowlines due to warm melt season conditions has led to ongoing mass loss that will lead to continued declines in the Lekhziri Glacier system. This is one example of the widespread retreat of glaciers in the region chronicled by Levan Tielidze. The high snowlines of 2017 and 2022 have been noted for Gora Gvandra glaciers and Zeno Svaneti glaciers.

Lekhrziri Glacier in 2013 Landsat image illustrating the retreat and separation of the three tributaries central (Lc), eastern (Le) and western (Lw). Red arrow indicates 2013 terminus and purple dots the snowline.

Lekhrziri Glacier in 2022 Sentinel image illustrating the retreat and separation of the three tributaries central (Lc), eastern (Le) and western (Lw). Yellow arrows the 2022 terminus locations aand green arrows the small lake at headwaters of Mestiachala River Basin.

Suatisi Glacier Retreat, Mount Kazbek, Georgia

On June 27, 2016May 2, 2024 By mspeltoIn Caucasus Glacier retreat, glacier climate change, Glacier Observations

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.

Khimsa Glacier Retreat, Georgia

On February 27, 2014March 2, 2014 By mspeltoIn Glacier Observations3 Comments

Khimsa Glacier is a rare significant glacier south of the main crest of the Caucasus Mountains in Georgia. The glacier drains north to the Bzyb River, and then the Black Sea. The rivers upper reach is quite undeveloped and there is no hydropower along the river to date. The glacier flows from an elevation of 3000 m to 2650 m. In 1998 the glacier was 1.6 km long with a narrow terminus at the red arrow. At the transition to the glacier’s upper eastern slopes at Point A, there is only one small rock exposure. By 2013 the glacier has retreated 400 m to the yellow arrow, having lost 25% of its length in 15 years. The area of bedrock exposed on the upper eastern slope, at Point A, is significant now indicating thinning even high on the glacier. The glacier will soon separate near Point A into an upper and a lower section. In the Google Earth image the current terminus is indicated with orange dots and the glacier flow with blue arrows. Like Psysh Mountain glaciers 25 km north Khimsa Glacier thinning high on the glacier indicates it cannot survive current climate. Caucasus Mountain glaciers are in a period of rapid retreat (Shagedenova et al, 2009), that is attributed mainly to rising summer temperatures. Khimsa Glacier’s retreat parallels that of glaciers along the main crest of the Caucasus such as Kirtisho or Azau Glacier, though as a percent of total area lost it is greater.

1998 Landsat image

2013 Landsat image

2010 Google Earth image

Kirtisho Glacier Retreat, Georgia

On December 17, 2012December 17, 2012 By mspeltoIn Glacier Observations

The southern flank of the Caucasus Mountains is in the nation of Georgia. Ten kilometers southwest of the Lednik Karaugom Glacier, Russia from the previous post is Kirtisho Glacier a 4.5 km long valley glacier, a small subglacier KS is also examined in this post. The glaciers in the Causcasus Mountains have been undergoing a significant retreat, the USGS, (2010) Satellite Image Atlas of Asia, noted that nearly all of the 65 glaciers examined in this region experienced significant retreat from 1987-2004. Shahgedanova et al, (2009) noted a 8 meters per year average retreat rate for the 1985-2000 period. To get a feel for the terrain watch the trailer for the On the Trails of the Glaciers- Caucasus 2011. The video does not show Kirtisho Glacier but does indicate the nature of the terrain. This is a project of an Italian group Macromicro, that had contacted me about an upcoming expedition to Alaska in 2013. Landsat images from 1986 (second image) and 2012 (third image) along with 2011 Google Earth imagery (top and bottom image) are shown below. Kirtisho Glacier has a top elevation of 3700 meters and a terminus that in 2012 is at 2600 meters, and was 2400 m in 1986. The snowline has typically been at 3300 meters, blue arrow, which is too high to sustain the terminus at 2600 m. The terminus position in 1986 is indicated by a red and yellow arrow that are also used in the 2012 imagery and the 2011 terminus closeup. The magenta arrow in the Landsat images indicates the beginning of a separation from an northern tributary, which is close to the snowline. The terminus itself is not crevassed in the lowest 400 meters, suggesting retreat will continue for this nearly stagnant section. KS the small glacier to the south, has decreased in area from 0.45 km2 in 1986 to 0.20 km2 in 2012. We also examine this more below.

The KS glacier viewed up close is quite thin, with limited crevasses. The red arrows indicate rock protruding through this glacier in many locations. These rocks indicate how thin the ice is, and will help absorb heat and hasten melting as the rock outcrops expand. In 2011 and in the 2012 imagery there is no remaining snow on the glacier. A glacier without a persistent accumulation zone cannot survive (Pelto, 2010). KS glacier will not survive much longer.