Tajikistan has begun using satellite technology to search for dangerous mountain lakes. Among the objects that scientists are monitoring are Lake Sarez, other high-altitude water bodies of the Pamir, and glacial lakes of Baralmoos.

Tajikistan has begun implementing the automated THAW tool, which helps identify new and anomalously changing mountain lakes that are potentially dangerous due to the risk of outburst.

The system uses data from the Sentinel-1 SAR satellite and the Google Earth Engine platform. It makes it possible to detect water bodies that require additional monitoring.

A practical workshop on working with THAW was held in Dushanbe with the participation of specialists from the Agency for Hydrometeorology, the Institute for the Study of Glaciers and the Cryosphere of the National Academy of Tajikistan, and the Institute of Water Problems, Hydropower and Ecology of the National Academy of Sciences. Participants tested the system’s capabilities for searching for potentially emerging lakes in individual glacial basins of Central Asia.

As noted in the materials of the GLOFCA project (Reducing the vulnerability of the population of Central Asia to floods caused by glacial lake outbursts under conditions of climate change), climate change is leading to accelerated glacier melting and the formation of new unstable lakes in high-altitude areas. When they burst, water can reach settlements, infrastructure, and agricultural land downstream.

Why can glacial lakes be dangerous?

Danger arises when water accumulates behind an unstable natural dam. Such lakes can grow rapidly and burst after heavy precipitation, abnormal heat, landslides, or other factors.

When a burst occurs, the flow can carry large volumes of water, rocks, ice, and mud, destroying roads, houses, and agricultural land.

According to research data by Professor Abdulkhamid Kayumov, Tajikistan has approximately 500–600 glacial lakes, and their number changes due to natural processes and climate change.

Lake Sarez: the main object of observation

Lake Sarez is one of the most well-known high-altitude water bodies in Tajikistan.

It formed in 1911 after a strong earthquake, when a large landslide blocked the Murgab River channel. This created the Usoi dam—a natural dam holding the lake’s water.

According to research titled “Lake Sarez—assessment of potential hazard based on natural analogues of the presumed chain of hazardous events,” the volume of water in the lake is approximately 16–17 cubic kilometers, and the height of the natural dam reaches approximately 500 meters.

The authors of the research note that the Usoi dam is currently considered stable with respect to water seepage and internal deformations. However, satellite observations reveal slope movements around the lake.

Researchers point out that a possible large landslide into the lake could create an impulse wave capable of causing overflow over the dam and subsequent destruction.

Satellite monitoring of the Sarez area is also used to assess slope movement. Research published in the journal Applied Sciences notes that Sentinel-1 data allows remote tracking of slope deformations in the lake area.

Baralmoos: lakes that have already caused debris flows

If Sarez is the most well-known example of potential threat, then the Baralmoos Glacier (Sayido Nasafi) is one of the areas where the consequences of glacial lake outbursts have already been recorded.

The glacier is located in the Lyakhsh District on the northern slope of the Petr Pervyy Ridge. It contains several unstable lakes that may pose a threat to settlements and roads located downstream.

According to GLOFCA project data, the Baralmoos Glacier is a complex valley glacier 10.7 km long with an area of 6.3 sq. km. Its surface is covered with moraine material, and glacial lakes are found on the glacier. Meltwater from the glacier feeds the upper reaches of the Ragnou River and partially the Surkhob River basin.

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Researchers note that water-glacial debris flows arising from glacial lake outbursts are among the most dangerous types of debris flows. Such processes have already been observed on the glacier.

Since 2018, cases of lake outbursts here have become more frequent. Between 2018 and 2021, five outbursts were recorded, and in 2023 alone, five more such events occurred. These floods damaged transportation infrastructure along the Surkhob River, including sections of the international highway.

The roads Dushanbe–Lyakhsh and Nurabod–Sangvor, as well as several settlements, are at risk.

Scientists from the Institute for the Study of Glaciers and the Cryosphere of the National Academy of Sciences of Tajikistan also recorded the consequences of Baralmoos glacial lake outbursts. According to their data, in 2023, five powerful debris flows occurred, which were accompanied by blockage of the Surkhob River channel and destruction of a section of the international highway in the Lyakhsh area.

To monitor the area, specialists install sensors that allow tracking of water level, temperature, and other parameters. Bathymetric surveys and modeling of possible outburst scenarios are also conducted.

Lakes of the Gunt River basin

The Gunt River basin is among the areas of Western Pamir where specialists study potentially dangerous high-altitude lakes.

In the research titled “Monitoring, modeling, and mapping of GLOF hazard for selected lakes,” it is noted that specialists conducted bathymetric surveys and modeling of possible outbursts of 21 outburst-prone lakes within the valleys of the Toguzbuloq, Gunt, Shakhdar, Bartang, Panj rivers and their water basins.

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In GBAO along the basins of the Panj River and its major tributaries—the Gunt, Shakhdar, and Bartang—there are more than 300 lakes. Among the largest natural lakes in the region, scientists name Karakul, Rangkul, Zorkul, Sarez, and Yashilkul.

At the same time, researchers note that information about glacial lakes remains limited, and comprehensive monitoring after the collapse of the Soviet Union has been insufficient due to lack of resources.

Lower Varshezkulь

This is another lake that was studied due to outburst risk. It is located in the basin of the Varshezdar River, a tributary of the Gunt. The research was conducted by specialists from the Aga Khan Agency for Habitat Branch in Tajikistan together with scientists from Lomonosov Moscow State University. They conducted a bathymetric survey and modeled the possible consequences of a lake outburst.

According to scientists’ calculations, the volume of water in the lake is approximately 1.94 million cubic meters. In one outburst scenario, the flow could reach the settlements of Varshez and Abuali Sino, and the flooding depth in certain places could reach up to 10 meters.

Lakes of the Shakhdar River basin

Shakhdar is another area of Western Pamir where specialists study possible threats related to high-altitude lake outbursts.

As part of research on potentially dangerous lakes of Western Pamir, the Shakhdar basin is included in the list of territories where hazard assessment and modeling of possible outburst consequences were conducted.

As researchers note, some glacial lakes form as a result of glacier retreat.

“Some of them can be held back by unstable moraine formations, and when natural dams are destroyed, they can cause powerful debris flows.

Lakes of the Bartang River basin

The Bartang basin is one of the most studied areas due to the location of Lake Sarez and other high-altitude water bodies here.

In scientific research on potentially dangerous lakes, Bartang is also considered among the basins where assessment of glacial lake outburst risk was conducted.

The distinctive feature of the area lies in the combination of several factors: the presence of glaciers, steep mountain slopes, and high seismic activity.

… Climate change is causing glaciers to continue melting, and new lakes are appearing in high-altitude areas. Therefore, specialists are focused on monitoring, risk assessment, and creating early warning systems.