The Devdoraki Glacier in the Georgian Caucasus Keeps Collapsing

On May 17, 2014, a catastrophic rock-ice avalanche and glacial mudflow took place in the Tergi (Dariali) gorge, blocking strategic infrastructure in Georgia. The disaster resulted in the death of nine people. About 200 people were evacuated by helicopter from a border crossing checkpoint and nearby areas. Glacial mudflow destroyed the Trans-Caucasus gas pipeline, Dariali Hydropower Plant, and an international road connecting Georgia and Russia. This event inflicted several tens of millions of Georgian lari in damages to the country’s budget.

Sequences of the collapse

According to archival data, at least six ice and ice-rock avalanches fell from the Devdoraki Glacier onto the Tergi River valley during the period 1776-1876, the two largest occurring on June 18, 1776 and on August 13, 1832. The first blocked the Tergi River for three days and was breached catastrophically; the second was about 100 meters high and about 2 kilometers wide and blocked the Tergi River for 8 hours. After breaking the dam, the glacial muflow caused a great amount of damage to Vladikavkaz in North Ossetia, Russia.

Since 1832, several new blockages were forecasted, but either the ice-debris masses did not reach the Tergi River, or the forecasts failed altogether. For example, the Devdoraki Glacier advanced in 1866 and 1867, raising alarm and forcing researchers to monitor its position. But the ice debris developed slowly and the Tergi River was not blocked. Again, in 1876, there was a danger of a blockage since the glacier greatly increased and advanced by about 150 meters.

Scientists have published other observations of the Devdoraki Glacier, up to the first decade of the 20th century (Tielidze et al., 2019).

Latest investigation

I, along with several colleauges, published in April work that presents the sequence of the Devdoraki Glacier hazards and analyzes the latest collapse, which occurred on May 17, 2014.

An ASTER image from May 16, 2014 shows traces of relatively small rock fall, revealing instability in the glacier. (Figure 1a). The result of the disaster is shown on the Landsat image from July 11, 2014 (Figure 1b) and in the PLEIADES image from May 18, 2014 (Figure 1c).

Figure 1. a – ASTER image 16/05/2014; b – Landsat L8 image 11/07/2014; c – PLEIADES image 18/05/2014

The resulting mudflow into the Tergi (Dariali) Gorge blocked the Tergi River for several hours, creating a 20-30 meter-deep lake (Figure 2) with a volume of at least 150,000 cubic meters. The height the ice and rock debris fell from the glacier face to the gorge was about 3.2 km, while the distance was about 10.2 km.

We estimate that the leading face of the Devdoraki Glacier advanced about 180 m between 2014 and 2015, which was caused mostly by rock-ice avalanche deposits. This part of the glacier should countine to be monitored as it could heighten debris flow activity in the future.  

Figure 2. Tergi (Dariali) gorge, result of Devdoraki glacial-mudflow (17/05/14) (Source: Levan Tielidze).

Possible causes

We considered the main hypotheses behind these events, namely a) tectonic and seismic (Figure 3a), b) permafrost (Figure 3b), c) volcanic, and d) morphological factors; interpreted the data for mechanisms and velocities of the catastrophic movement, and argued that the 2014 event should not be classified as a glacier surge, althoughthe possibility of similar glacial surges can not be excluded.

Figure 3. a – Tectonic map of the study region (compiled by authors). b – Permafrost zonation index map

The Kazbegi-Jimara massif should be considered as a natural laboratory that enables the investigation of rock-ice avalanches and glacial mudflows.


We recommend to construct a road tunnel on the east (right) slope in the Tergi valley (Figure 1c) and to discontinue the Dariali Hydropower Plant construction in order to mitigate risk and avoid incidents including deaths in the future.

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Glacier change in the Georgian Caucasus Mountains

From the Cryosphere: “Changes in the area and number of glaciers in the Georgian Caucasus Mountains were examined over the last century, by comparing recent Landsat and ASTER images (2014) with older topographical maps (1911, 1960) along with middle and high mountain meteorological stations data. Total glacier area decreased by 8.1±1.8% (0.2±0.04%yr−1) or by 49.9±10.6km2 from 613.6±9.8km2 to 563.7±11.3km2 during 1911–1960, while the number of glaciers increased from 515 to 786. During 1960–2014, the total ice area decreased by 36.9±2.2% (0.7±0.04%yr−1) or by 207.9±9.8km2 from 563.7±11.3km2 to 355.8±8.3km2, while glacier numbers decreased from 786 to 637. In total, the area of Georgia glaciers reduced by 42.0±2.0% (0.4±0.02%yr−1) between 1911 and 2014. The eastern Caucasus section had the highest retreat rate of 67.3±2.0% (0.7±0.02%yr−1) over this period, while the central part of Georgian Caucasus had the lowest, 34.6±1.8% (0.3±0.01%yr−1), with the western Caucasus intermediate at 42.8±2.7% (0.4±0.03%yr−1).

A view of the Caucasus Mountains, Svaneti, Georgia. (Credit: Wikimedia Commons/sv:User:Ojj! 600)

Glacial lake expansion on the Tibetan Plateau

From Society & Natural Resources: “Global climate change is causing the majority of large lakes on the Tibetan Plateau to expand. While these rising lake levels and their causes have been investigated by hydrologists and glaciologists, their impacts on local pastoral communities have mostly been ignored. Our interviews with pastoralists in central Tibet reveal their observations and beliefs about Lake Serling’s expansion, as well as how its effects are interacting with current rangeland management policies. Interviewees reported that the most negative effects on their livelihoods have been reduced livestock populations and productivity due to the inundation of high-quality pastures by saline lake water. However, pastoralists’ collective efforts based on traditional values and norms of sharing, assistance, and reciprocity have helped them cope with these climate change impacts. These local, traditional coping strategies are particularly worthy of attention now, given that the transformation of traditional pastoralism is a goal of current government development initiatives.”

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An early warning plan for Ecuador

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Georgia: Glaciers and Geopolitics

A glacier flows down a gorge between two peaks in the Caucasus Mountains. Source: Flickr, Pavel Karafiat.
A glacier flows down a gorge between two peaks in the Caucasus Mountains. Source: Flickr, Pavel Karafiat.

Glaciers in the Republic of Georgia have seen a 16 percent decline over the last 150 years, according to a new chapter in the World Regional Geography Book Series which describes this country, located in the Caucasus Mountains. The melting of glaciers has also resulted in fragmentation as larger glaciers are broken up into smaller ones (786 glaciers occupy a total area of 550 square kilometers). These changes may have important implications not only for the geology of the Caucasus Mountains but for the thousands of Georgians whose lives intersect with glaciers, authors of the chapter stated.

Georgia occupies a disproportionate share of headlines in the world for a country with a population of 3.7 million and a land area of 640,000 square kilometers; it is slightly more populated than Connecticut and slightly larger than Florida. Ethnic and geopolitical tensions are high, and the country was briefly at war with Russia in August of 2008 over the status of South Ossetia. In 2003, the country underwent a “Rose Revolution,” which saw the end of 30 years of rule by the country’s Soviet-era leader and was accomplished by peaceful means.

A tower constructed in the European Dark Ages in the northwestern province of Svanetia. Source: Wikipedia
A tower constructed in the European Dark Ages in the northwestern province of Svanetia. Source: Wikipedia

While the political process has improved stability and confidence in the Georgian government, the country is still subject to the geopolitical demands that arise from its unique location. Together with Azerbaijan and Armenia, it forms a barrier between Russia and the Middle East that stretches from the Caspian Sea in the east to the Black Sea in the west. Oil from the Caspian Sea must pass through Georgia in order to reach western markets via the Black Sea and the Mediterranean.

While recent geopolitics have involved the Russia, Turkey and Azerbaijan as key neighbors, the area has a more ancient history that is very rich. As it lies in such a key area, it was vied over by forces including, in relatively recent times, the Russian Empire, and in relatively ancient times the Persian and Byzantine Empires. Ancient artwork and archaeological features abound in areas such as Svaneti, a province in the northwest of Georgia.

As Georgia pursues an independent path, it must manage the challenges of climate change which will accelerate glacier loss and impact its citizens, the authors wrote. In 2007, the trans-Caucasus highway was shut down after 35 avalanches in one day covered them with snow and debris. Resettlement programs are one part of the solution. 8,500 people have been moved out of harm’s way since 1987, a year in which a record snowfall, continuous over 46 days, left snow that reached 16 meters in depth in some areas.

Rock forms left behind in a stream by the Challadi Glacier. Courtesy of Flickr user Orientalizing.
Rock forms left behind in a stream by the Challadi Glacier. Courtesy of Flickr user Orientalizing.

One mechanism by which glaciers in this area contribute to avalanches is a phenomenon known as glacial surge, which is a sudden slide by the leading edge of the “river of ice” that is a glacier. This can be triggered by a change in glacier slope, which frequently occurs in the jagged Caucasus Mountains. The glacial surge can send chunks of the glacier’s rock and ice crashing down a slope and into populated areas. Just over the border on the Russian side of the Caucasus, this sort of slide by the Kolka glacier is believed to be the cause of a 2003 avalanche that killed 125 people. Avalanche risks spread throughout Georgia, which has mountains along both its northern and southern borders, though the eastern portion of the country has a slightly larger share of the at-risk area.

Though glaciers pose risks to people who live near them, they also play an important role in defining the area they live in. The remarkable geography that can be seen on the slopes of the Caucasus Mountains, including rock formations and polygonal land shapings, come about through peri-glacial processes, whereby glaciers carve and reshape the land as they pass over it. Keeping Georgian citizens safe fro the dangers that these dynamic glaciers ring is a daunting challenge that this country faces as it pursues a path of self-determination.

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The black southern cod, Patagonotothen tessellata, in southern Chilean Patagonia. (Credit: Fundación Ictiológica)
The black southern cod, Patagonotothen tessellata, in southern Chilean Patagonia. (Credit: Fundación Ictiológica)

“The black southern cod, Patagonotothen tessellata, is the most important notothenioid fish species in terms of abundance in southern Chilean Patagonia. However, studies on its trophic ecology are scarce. [This study assessed] the spatial variation in the diet of P. tessellata between two localities, one with oceanic influence (Staples Strait) and another with continental influence (Puerto Bories)… The black southern cod presents spatial differences in diet composition among contrasting environmental localities… The results provide evidence of two dietary patterns depending on the type of environment in which they are distributed, highlighting the potential role of the environmental variables on the availability and abundance of potential prey and in structuring diet.”

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Glaciers in the Spotlight: Salman Khan films dramatic scene at Thajwas glacier, Kashmir

“No doubt Salman Khan’s films are incredible exciting and dramatic, but his forthcoming release ‘Bajrangi Bhaijaan’ has even gotten better… ‘The Bajrangi Bhaijaan climax was shot at the base of the Thajwas glacier outside Sonamarg. Located at 10,000 feet above sea level… the 300 strong technical crew had to trek for an hour through snow every morning to reach the location. Added to this was were the 7000 extras that we had on set every day. Transporting them in hundreds of buses and then embarking on the hour-long trek was a huge logistical challenge for the production. To add to their woes was the sub zero temperatures and hail storms that would interrupt the shoot,’ said Kabir Khan who has previously worked with Salman in ‘Ek Tha Tiger.’”

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Glacial Melt in Georgia, Communities Threatened by Avalanche

Mt. Ushba in Georgia (Credit: Levan Gokadze, Flickr)
Mt. Ushba in Georgia (Credit: Levan Gokadze, Flickr)

“Considering its size, Georgia has a large number of glaciers. In the mountains of Georgia, there are about 786 registered glaciers, with a total area of about 550 km. About 82.5 % are in the upper courses of the Kodori, Inguri, Rioni, and Tereck rivers. For the past 150 years, significant glacier retreat (0.8–1.7 km) and shrinking of their area by 16 % has been observed. Since the middle of the 1940s, the glaciological situation has been characterized by a sharp reduction in the glacial area, but with the simultaneous increase in their number as glaciers disintegrated into separate smaller ones, although at the same time separate movements have also taken place. Avalanches are common in Georgia. Nearly 340 inhabited places are under the threat of avalanche attacks. About 31 % of the territory of Georgia is subject to avalanches (18 % in eastern and 13 % in western Georgia).”

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Dariali gorge may be in danger from new hydroelectric plant

The construction of a hydropower plant near Georgia's Dariali Gorge could endanger the surrounding landscape. (photo: Rita Willaert)
The construction of a hydropower plant near Georgia’s Dariali Gorge could endanger the surrounding landscape. (photo: Rita Willaert)

Along Georgia’s border with Russia, about two hours north of the Georgian capital of Tbilisi, the Tergi River flows on an almost 400 mile journey down from the Devdorak Glacier atop Mount Kazbek to the Caspian Sea. The river has been a valued source of water for the communities along its banks for thousands of years, and the gorge which it cuts through the Caucasus has been a key trade route as well.

It has recently become the site of a controversial hydroelectric project. After not one, but two major landslides, the Dariali Hydropower Plant, located on the river, has become a topic of recent debate. The May 2014 landslide left three power plant workers dead and five others missing, it also completely impeded the Dariali Gorge, cutting of the region’s arterial roadway between Georgia and Russia, in addition to severing an essential natural gas pipeline providing Armenia with natural gas from Russia. The August landslide, reportedly larger than the one a few months before, resulted in the death of two more hydroelectric plant workers and necessitated a visit to the area by the Georgian president.

These events are not new for the region, which has been blighted by landslides for as long as local history remembers. This history makes local residents concerned. Other hydroelectric projects have succumbed to such hazards. For this reason and others ,the Dariali project, which would provide an estimated 108 Megawatts of electricity to the region, has already run into political controversy. The public does not fully accept the project, Eighty to 90 percent of the Tergi River would have to be diverted, leaving almost five miles of the riverbed completely dry, and threatening the local trout population. The project necessitated the rezoning of the area, removing its status as a national park under legal protection. Local people were concerned that construction began before a permit was issued, or before even mandatory public hearings were held.

Another issue is contribution of global warming to the latest two landslides. Devdorak Glacier, like other glaciers in the Caucasus, has been retreating in recent years. The meltwater could lead to increased water flow and thus contribute to natural erosion, increasing the risk of floods and landslides. Such dangers are well-established in the valley, as demonstrated by accounts as far back as 1869. Douglas W. Freshfield gives this account in his “Travels in the Central Caucasus and Bashan“:

“M.E. Favre, of Geneva, a well-known geologist who visited the Devdorak Glacier a few weeks after ourselves, came to the following conclusion as to the nature of the catastrophe. No avalanche, he says, could without the aid of water traverse the space between the end of the glacier and the Terek (Tergi river), and he accounts for the disasters which have taken place in the following way. He believes the Devdorak Glacier, to which he finds a parallel in the Vernagtferner Glacier in the Ötzthal Alps, to be subject to periods of sudden advance. During these the ice finds no sufficient space to spread itself out in the narrow gorge into which it is driven, and is consequently forced by the pressure from behind into so compact a mass that the ordinary water-channels are stopped, and the whole drainage of the glacier is pent-up beneath its surface. Sooner or later the accumulated waters burst open their prison, carrying away with them the lower portion of the glacier. A mingled flood of snow and ice, increased by earth and rocks torn from the hillsides in its passage, sweeps down the glen of Devdorak. Issuing into the main valley it spreads from side to side, and dams the Terek. A lake is formed, and increases in size until it breaks through its barrier, and inundates the Dariali Gorge and the lower valley.” [ed: place names have been modernized from original text]

Only time will tell whether or not the Dariali Hydropower Plant will be realized, and if so, what the effects will be for the region. Looking back at recent history, however, the safety of the project itself and the valley below seems suspect at the least.

For more information about the Dariali Gorge landslide see:

For a related GlacierHub story see:

Glacier stories you may have missed – 9/08/14

(photo: Georgia Ministry of Internal Affairs)
(photo: Georgia Ministry of Internal Affairs)

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