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.

Khanasankoi Glacier, Russia Separation and Full Snowcover Loss

On September 9, 2020April 23, 2024 By mspeltoIn Caucasus Glacier retreat1 Comment

Khasankoi Glacier in 1985, 1998, 2013 and 2020 Landsat imagery with Point 1-4 indicating locations where bedrock expansion is occurring with Point 1 and 3 separating the glacier into three parts. Note complete lack of snowcover on 8-26-2020.

Khasnakoi Glacier is a north facing slope glacier just south of Mount Elbrus that drains into the Kuban River. The Greater Caucasus contain approximately 2000 glaciers with a total area of ~1200 km2(Tielidze and Wheate, 2018). Significant positive trends in annual and summer temperature from 1960-2014 have driven large overall glacier area loss, 0.53% per year, leading to the loss of over 300 glaciers (Tielidze and Wheate, 2018). Here we examine Landsat images from 1985-2020 to identify key changes of the glacier.

In 1985 the glacier extended 4.6 km from east to west without interruption and featured three primary termini. The glacier in 1985 has an accumulation area ratio (percent snowcovered) of 60%. By 1998 there is limited retreat the glacier is still once continuous glacier and the accumulation area ratio is 40. By 2013 at Point 1 a bedrock ridge is emerging. At Point 2 a few outcrops of rock are evident emerging from under the thinning glacier. The same is the case at Point 4. At Point 5 a new lake has developed at the margin. The accumulation area ratio in 2013 is 25%. In 2020 the accumulation area ratio is 0% snowcover. A pair of ridges now bisect the glacier at Point 1 and Point 3. At Point 2 the rock outcrop has expanded into one large region. At Point 4 a bedrock area has expanded at the head of the glacier. At Point 5 retreat has left the newly formed lake of less than a decade ago isolated from the glacier. This is not the first year of poor snowcover.

The mapped boundary of the glacier below provided by Levan Tieldze illustrates the glacier boundary in 1960, 1986 and 2014, illustrating a 29% decline in area. The loss of snowcover in 2020 is not the first summer when this has been observed in the Caucasus in 2017 Gora Gvandra did not retain snowcover. For Dzhikiugankez Glacier on the slopes of Mount Elbrus there has been a persistent low snowcover by end of summer since 2013. Tieldze (2019) explained the connection of climate to receding glaciers in the Caucasus using Tviberi Glacier in Georgia as an example.

Image from Levan Tieldze indicating the extent of the glacier in 1960 (red), 1986 (black) and 2014 (blue) on a 2016 SPOT image. There is still some connection above Point 1.

Map of the region from when Khasankoi Glacier was contiguous.

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.

Lednik Midagrabin Retreat, Caucasus, Russia

On July 30, 2015May 2, 2024 By mspeltoIn Caucasus Glacier retreat, climate change glacier retreat, glacier climate change

Lednik Midagrabin is a large glacier draining northwest from Gora Dzhimara in North Ossetia, Russia. Stokes et al (2006) examined Caucasus glaciers during the 1985-2000 period and found that 94% of the glaciers have retreated, 4% exhibited no overall change and 2% advanced. The mean retreat rate is 8 m/year, with the largest glacier retreating the fastest. Shahgedanova et al (2009) observed that the retreat was driven by a large rise in summer temperature in the alpine zone, and that this will continue and generate substantial changes in the timing and amount of glacier runoff. Here we examine the changes in this glacier from 1989-2015. This region has had a particularly warm start to the melt season in 2015 prompting this examination, note the NOAA temperature anomaly for the Caucasus Region.

Google Earth Image

NOAA 2015 Temperature departure map for June 2015 with the Caucasus region indicated.

The glacier begins on the slopes of Dzhimarra at 4200 m and in 1989 the glacier terminated at the red arrow at 2950 m. The snowline at the end of August, 1989 was 3700 m. The green arrow indicates the extent of the clean blue glacier ice of the tributary from the north In 2014 the glacier had retreated to a terminus location at the red arrow. The snowline at the end of August 2014 was at 3800 m. In mid-July of 2015 the snowline has already reached 3700 m, with the melt season only half over. This will lead to substantial mass loss. The main terminus has retreated to the yellow arrow a distance of 900-1000 m since 1989 and now terminates at 3050 m. This is close to the maximum rate of 38 m/year identified by Stokes et al (2006) for the any glacier in the mountain range from 1985-2000. This indicates Midagrabin is one of the faster retreating glaciers in the Caucasus and that the rate of retreat has increased. The northern tributary clean ice zone has been reduced in length and width, now terminating 600 m further upglacier. The northern tributary has had little retained snowpack in 2014 and again in 2015. The tributary begins at 4000 m, which is not high enough in recent years to sustain this arm of the glacier. The high snowlines of recent years will lead to continued retreat. The glacier poses little geologic hazards of flooding compared to some other retreating glaciers in the area such as Bashkara Glacier.

August 1989 Landsat Image

August 2014 Landsat Image

July 2015 Landsat image

Lednik Karaugom Glacier Retreat Caucasus Mountains, Russia

On December 14, 2012February 22, 2014 By mspeltoIn Glacier Observations1 Comment

Lednik Karaugom Glacier is a large 13 km long, valley glacier in the Caucasus Mountains of Northern Ossetia, Russia. The glacier drains into the Urukh River which joins the Terek River and then flows into the Caspian Sea. This post compares Landsat imagery from 1986, 2010 and 2012, an image from the USGS in 2002 and Google Earth imagery from 2009. This glacier has experienced a general retreat like all the glacier draining north from the Caucasus Mountains. 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, noting a retreat of Karaugom of 600 m. Maria Shahgedanova, has an ongoing project examining Caucasus glaciers. Shahgedanova et al, (2009) noted a 8 meters per year average retreat rate for the 1985-2000 period. The glacier retreat has led to an increase in debris cover and an increase in the number of proglacial and supraglacial lakes. (Stokes et al , 2007) This glacier begins at the Russia-Georgia border and extends up to the base of Gora Uilpata at 4200 meters. There is a substantial icefall separating the accumulation zone above 3500 meters from the ablation zone of the valley tongue beginning at 2500 m.from 1987-2002. In the series of images below the yellow arrow indicates the 1986 terminus position, the pink arrow the 2012 terminus position, the orange arrow the 2002 terminus position and the blue arrow the former connection with a tributary. The retreat from 1986 to 2012 is 1300 meters, about 50 meters/year. The retreat of the tributary from the main glacier has been 200 meters, or 8 meters/year.

A closeup of the terminus indicates the amount of debris cover, and the formation of ogives at the base of the icefall. The lateral moraine marking the previous ice surface elevation is also noted with a green arrow. This glacier remains vigorous in its flow, with substantial crevassing and ongoing crevasse formation. The retreat is ongoing but the end of the glacier is not stagnant, though the lower 300 meters has reduced crevassing and width. The degree of crevassing at the green arrows at a small icefall 300 meters above the terminus indicates both ice thickness and flow and suggest that the retreat will likely be reduced in the near future. The behavior is similar to that of Lednik Fytnargin and Irik Glacier on Mount Elbrus