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News Category: Glacier Lake Outburst Floods

Study on the effectiveness of GLOF DRM measures in the Ala-Archa valley, Kyrgyz Republic

Originating high in the Tien Shan mountains, the Ala-Archa River flows through Ala-Archa National Park before reaching Bishkek, Kyrgyz Republic’s capital. The park was established to protect the unique wildlife of the Northern Tien Shan and today is one of the country’s most popular destinations for hiking and tourism.

The valley is also among the most debris-flow-prone areas in the region. Outbursts from glacial lakes such as Aksai and Teztor have repeatedly triggered destructive debris flows. The most recent major event, recorded in 2024, destroyed more than 25 houses and caused one fatality.

Against this backdrop, a new scientific article published in «Natural Hazards and Earth System Sciences» evaluates how different disaster risk reduction measures can reduce the impacts of glacial lake outburst floods (GLOFs) and debris flows using Ala-Archa National Park as a case study. Utilizing numerical mass movement models, the study assessed three measures: the artificial lowering of lake levels, a deflection dam, and a retention basin. It presents a comparison of the impact of such measures on the exposure of people and infrastructure to the risk of GLOFs and debris flows.

The study, led by Laura Niggli and co-authored by scientists from the University of Zurich, the Central Asian Institute for Applied Geosciences (CAIAG) and the University of Central Asia (UCA), was conducted within the framework of the GLOFCA project. Funded by the Adaptation Fund and implemented by the UNESCO Regional Office in Almaty in partnership with the University of Zurich, the project supports regional efforts to reduce vulnerability to GLOFs across Central Asia.

The installation of GLOF Early Warning Systems is a key component of the GLOFCA project. The findings of this study provide a quantitative basis for evaluating structural measures that can complement Early Warning Systems and strengthen overall risk reduction strategies. The results show that although artificial lowering of lake levels offers the best cost-to-benefit ratio, it is important to also consider the relatively high maintenance costs of such measures.

Holger Frey from the University of Zurich, co-author of the study, emphasises that “The most effective, cheapest and most sustainable approach to disaster risk management is still long-term spatial planning, based on systematic hazard maps.”

The link to the study: https://nhess.copernicus.org/articles/26/733/2026/


GLOFCA in Tajikistan: strengthening an alternative road in Lakhsh district

One of these measures focuses on improving an existing alternative road between the villages of Korvonguzar and Duagba, including widening the carriageway and laying a gravel surface.

Lakhsh district is classified as a high-risk area where mudflows, landslides and floods occur regularly. The upper parts of the district host several glacier lakes, including those located in the lower section of the Said Nafisi (formerly Baralmos) Glacier. Outbursts from these lakes periodically damage sections of the main road running along the Surkhob River.

Glacial lakes, Said Nafisi (formerly Baralmos) Glacier

In such situations, the alternative road between Korvonguzar and Duagba remains the only transport link, providing access to medical and emergency services. It ensures connectivity for more than 20 settlements in Lakhsh district, with a total population exceeding 20,000 people, including communities in border areas with the Kyrgyz Republic. Previously, this route was in poor condition and did not provide reliable access, particularly during adverse weather conditions.

The road along the Surkhob river

To improve safety and accessability, the GLOFCA project supported road improvement works. Prior to construction, specialists conducted an engineering assessment to identify sections most exposed to water impact and erosion. Then the road was widened, the surface levelled, and gravel laid on the most problematic sections. These measures aim to ensure more reliable, year-round access between settlements.

Further works are planned for vulnerable sections, including the installation of drainage structures to channel meltwater and rainwater and reduce the risk of road washout. Some additional measures are scheduled for the warmer season, when weather conditions will allow continued reinforcement of the route.

In spring, slope greening is also planned along the alternative road. Tree planting will help stabilize soils, reduce erosion, and increase the road’s resilience to water impacts, combining engineering solutions with nature-based approaches.

The works in Lakhsh district form part of the broader objective of the GLOFCA project to reduce climate-related risks by strengthening infrastructure and enhancing the resilience of communities living in high-mountain areas under changing climate conditions.

GLOFCA installs risk information boards in Talgar and Esik, Kazakhstan

In Almaty Region, the project “Reducing vulnerabilities of populations in Central Asia region from glacier lake outburst floods in a changing climate” (GLOFCA), implemented by UNESCO with support from the Adaptation Fund, has completed the installation of risk information boards and hazard maps in the Talgar and Esik river basins, two of the project’s pilot sites.

Both rivers originate from the Ile-Alatau mountains and flow through several settlements, serving as important recreational and tourism areas. These territories are classified as high-risk zones due to the presence of moraine lakes, steep terrain, and frequent debris-flow activity.

To enhance public awareness and improve preparedness, GLOFCA installed warning signs and risk-map boards at each pilot site. The signs provide clear and accessible guidance for residents, hikers, and tourists on local natural hazards and recommended safety measures.

The glacier lake outburst flood (GLOF) risk maps were developed by experts from the University of Zurich. They modelled the potential impact zones under several scenarios. These maps serve as an important tool for local authorities, emergency services, and visitors to better understand and manage the risks.

The installation of the boards complements recent engineering and risk-reduction measures carried out under the GLOFCA project in Talgar and Esik, contributing to stronger community resilience and improved risk communication in the region.

Major collapse of the Dehdal Glacier

On 25 October 2025, at around 11:00 a.m., a large ice mass collapsed from the Dehdal Glacier (formerly known as Dedal), located on the northern slopes of the Peter the First Range, near the village of Safedobi in Tajikabad District.

According to the Committee for Emergency Situations and Civil Defence under the Government of the Republic of Tajikistan, a section of the glacier, approximately 2 km long, 25 m high, and 150–200 m wide, broke off and slid down the valley. By 14:00, the situation had stabilized, and no casualties or serious damage were reported.

This is the second collapse of the Dehdal Glacier in recent months. Kamoliddin Nazirzoda, Deputy Head of the Glaciology Centre of the Agency for Hydrometeorology of Tajikistan, explained:

“The activity of the Dehdal Glacier this year can be described as abnormal — no one expected a surge. This glacier is listed among the representative glaciers, and our Centre assessed its condition in 2020 and 2024. According to those studies, there were no signs of an imminent surge; we expected it in 25–30 years. However, this year two surges occurred in a row: the first on 18–19 September, when the glacier advanced more than 4 km, and the second at the end of October, when the ice mass moved another 5 km down the valley. Satellite images show that the activity had already started in early September.”

About the glacier

The Dehdal Glacier originates at an altitude of 4,600 metres above sea level and is a surge-type (or pulsating) glacier, whose movement occurs roughly every 40–45 years, according to the Glaciology Centre of the Agency for Hydrometeorology. Previous active phases of Dehdal were recorded in 1902, 1922, 1974, and 2016.

According to Kamoliddin Nazirzoda, the glacier’s dynamics are directly linked to climatic conditions — namely, the amount of precipitation and snow accumulation in its feeding area.

“After analyzing meteorological data from the past five years, we found that from late spring to early autumn this year, there was almost no precipitation, while temperatures remained high. This led to the degradation of the glacier’s structure. Another contributing factor was seismic activity. Several earthquakes were recorded in the area this year, which could also have influenced the movement of the ice mass.”

Outlook

The glacier’s surface remains active. The residual glacier continues to move forward at speeds of up to 40 metres per day, and there is a risk that another detachment could occur. There is also a risk that the ice mass and sediment accumulated downstream in the valley may subside during heavy rainfall, snowfall, potentially blocking the river channel flowing from the glacier. In this case, a temporary lake could form, and its outburst might damage the bridge on the Dushanbe–Vakhdat–Lakhsh highway leading to the Kyrgyz Republic, as well as affect farmland in the village of Gulrez.

According to the Committee for Emergency Situations, work is already underway in the valley to reinforce riverbanks and protect the bridge and nearby areas in case of new surges or water outbursts.

“We continue monitoring the glacier. In the coming days, our specialists will travel to the site to assess the likelihood of another surge,” added Kamoliddin Nazirzoda.

Why it matters

The recent glacier collapse highlights the urgent need to strengthen disaster risk reduction and establish early warning systems to protect mountain communities – efforts currently being implemented by the “Reducing vulnerabilities of populations in Central Asia from glacier lake outburst floods in a changing climate” (GLOFCA) project near the Said Nasifi (Baralmos) Glacier.

International conference in Tashkent on innovative methods for glacier monitoring

On 16 September 2025, an international conference titled “Innovative Methods for Monitoring Mountain Glaciers under Climate Change and Current Challenges in Glaciology” was held in Tashkent, Uzbekistan. The event was organized by the Hydrometeorological Research Institute (NIGMI) with the support of the UNESCO Regional Office in Almaty and its two flagship projects.

The conference brought together scientists, practitioners, and government representatives from Central Asia and beyond to exchange the latest research and practical experience in glaciology. Discussions focused on the importance of snow and glacier monitoring for water security, the risks of glacier lake outburst floods, and the use of modern digital tools, including MODSNOW. The GLOFCA project highlighted the development of early warning systems and work with local communities to reduce disaster risks.

The conference provided an important platform for strengthening regional cooperation and identifying practical, policy-relevant solutions for climate adaptation and disaster risk reduction.

Series of Glacier Lake Outburst Floods in Lakhsh District: Another Call to Action

On the evening of 10 August 2025, a powerful mudflow descended in the Archakapa area of Lakhsh District, Tajikistan, originating from a glacier lake on the Said Nafisi Glacier (formerly Baralmos). The flow blocked the Surkhob River for more than two hours, washed away over 400 metres of road along the Vahdat–Rasht–Lakhsh–Saritash highway, and left behind piles of rocks, mud, and debris. The drainage was a normal process for this type of glacial lake, but was worsened by high temperatures and accelerated glacier melt. Fortunately, there were no casualties. However, this is far from an isolated incident.

Kamoliddini Nazirzoda, Deputy Head of the Glaciology Centre at the Agency of Hydrometeorology of Tajikistan, explained:

“The Said Nafisi Glacier has become extremely unstable in recent years: several lakes of varying sizes have formed on its surface, which regularly experience partial outbursts during the warm season. Over the past five years, similar events have occurred 23 times. This summer alone, three major events took place in this area – on 14 July, 22 July, and 10 August. Each outburst leads to mudflows, blockage of the Surkhob River, and damage to the Vahdat–Rasht–Lakhsh international highway near the border with the Kyrgyz Republic. Road repairs can only begin after 10–15 days, as the sediment becomes waterlogged and remains unstable.”

Damage to the Vahdat–Rasht–Lakhsh international highway

According to Dr Evan Miles, an expert from the University of Zurich, the flooded area of the road and scale of damage has increased over the past several years. Dr Miles noted that Said Nafisi is a surge-type (pulsating) glacier, and that the development of these lakes is an unfortunate normal part of the surge cycle. It is possible that the lakes become even larger until the next surge, as was the case in 1998. For now, the recurring floods isolate part of Tajikistan and their increasing severity makes road repairs progressively more difficult.

Lakhsh District is a pilot area in Tajikistan part of the GLOFCA project, implemented by UNESCO and funded by the Adaptation Fund. In the near future, an Early Warning System will be installed here and alternative transport routes strengthened so that, even if the main road is blocked, residents remain connected to the outside world and can evacuate in time.

GLOFCA works to ensure that mountain communities are aware of the danger in advance and have time to protect themselves.

Impacts of the recent (10 Aug 2025) outburst