The investigation of avalanche activity in mountainous regions manifests an important aspect of public and infrastructure safety and protection, with particular attention to avalanches in hard-to-reach and poorly studied areas, like the Gissar-Alai Mountain Range. Remoteness, inaccessibility and increased cloudiness during the high avalanche season make field observations and applying optical satellite imagery for studying the avalanche activity in the Gissar-Alai extremely difficult. In such setting, radar technologies allowing to receive data regardless of weather and lighting conditions offer the best solution. The article describes the methodology for processing radar images of the Sentinel-1 satellite, as well as the results of decoding avalanche deposits in the Zeravshan, Gissar, Turkestan and Alai Ranges during the 2021-2022 season. The method underwent verification based on the Sentinel-2 multispectral data. In addition, the article characterizes the peculiar features of avalanche activity for each of the Gissar-Alai ridges, including the distribution of avalanche deposit zones by absolute heights, as well as slope steepness and exposure.

Abstract The prevalence and impacts of glacier lake outburst floods (GLOFs) in all glacierized mountain ranges globally underlines the importance of GLOF disaster risk management (DRM). A large variety of types of GLOF DRM measures exists, targeting the reduction of the hazard of a potential GLOF, of the exposure, or of the vulnerability of people and infrastructure. A wide range of such measures have been implemented in different mountain regions all over the world since the mid 20th century. While many of these measures have been reported, there are relevant gaps in the systematic documentation, analysis, and evaluation of GLOF DRM measures globally. A comprehensive compilation, classification and evaluation of GLOF DRM measures is required to establish a guidance for best practice approaches. DRM measures aiming at a reduction of the hazard component are typically structural measures, while vulnerability is addressed mainly by nonstructural measures. Hazard and exposure reduction measures cover all temporal ranges from short- to long-term interventions. The design and implementation of GLOF DRM measures is demanding due to harsh environmental conditions, remoteness, and rapidly changing hazard and risk situations on the one hand. Institutional and organizational aspects related to the funding, planning, and implementation of such measures, on the other hand, pose further challenges to successful GLOF DRM.

Glacier lake outburst floods (GLOFs) are among the most destructive natural hazards in high mountain areas. Mathematical modeling can help to assess the potential consequences of such outbursts, delineate hazard zones, and calculate characteristics of debris flows and floods. The study is focused on the Lake Bashkara outburst on September 1, 2017, forming a stony debris flow with a total volume of about 1*106 m3. The availability of extensive data on this outburst allows to simulate the event using the r.avaflow program. The software can account for up to three phases in the flow: liquid, solid and fine solid. In our case the number of phases was reduced to two: liquid and solid. The software utilizes the volume of entrained material, flow parameters, and pre- and post- GLOF Digital Elevation Models (DEMs) obtained by previous researchers. The results were compared with actual data on the outburst and previous numerical simulations. The limits of the debris flow hazard zone, depth values, flow speeds (averaging 6 m/s), and travel time to different control points correlate well with previous simulations and eye-witness estimates. Due to the involvement of solid material, the calculated values of flow speed and depth increased slightly comparatively to previous estimates. This work is the first attempt to calculate the pressure and kinetic energy of the flow for different sections in the channel, and to assess the amount of eroded and accumulated material, changed the terrain after the GLOF. The obtained inundation zone almost replicates the observed boundaries delineated using post-GLOF Pleiades image on September, 3. The tested model, r.avaflow, can be applied in the Mt. Elbrus region to assess the dynamics and impact zones of stony debris flows initiated by lake outbursts.

Populations and infrastructure in high mountain regions are exposed to a wide range of natural hazards, the frequency, magnitude, and location of which are extremely sensitive to climate change. In cases where several hazards can occur simultaneously or where the occurrence of one event will change the disposition of another, assessments need to account for complex process chains. While process chains are widely recognized as a major threat, no systematic analysis has hitherto been undertaken. We therefore establish new understanding on the factors that directly trigger or alter the disposition for subsequent events in the chain and derive a novel classification scheme and parameters to aid natural hazard assessment. Process chains in high mountains are commonly associated with glacier retreat or permafrost degradation. Regional differences exist in the nature and rate of sequencing—some process chains are almost instantaneous, while other linkages are delayed. Process chains involving rapid sequences are difficult to predict, and impacts are often devastating. We demonstrate that process chains are triggered most frequently by progressive failures, being the result of gradual landscape weakening and not due to the occurrence of a distinct process. If fluvial processes are part of the process chain the reach (or mobility) of process chains is increased. Increased mobility can also occur if sediment deposition areas along river channels are activated. As climate changes causes glacial environments to transform into sediment‐rich paraglacial and fluvial landscapes, it is expected that the mobility of process chains will increase in the future.

Thousands of glacier lakes have been forming behind natural dams in high mountains following glacier retreat since the early 20th century. Some of these lakes abruptly released pulses of water and sediment with disastrous downstream consequences. Yet it remains unclear whether the reported rise of these glacier lake outburst floods (GLOFs) has been fueled by a warming atmosphere and enhanced meltwater production, or simply a growing research effort. Here we estimate trends and biases in GLOF reporting based on the largest global catalog of 1,997 dated glacier‐related floods in six major mountain ranges from 1901 to 2017. We find that the positive trend in the number of reported GLOFs has decayed distinctly after a break in the 1970s, coinciding with independently detected trend changes in annual air temperatures and in the annual number of field‐based glacier surveys (a proxy of scientific reporting). We observe that GLOF reports and glacier surveys decelerated, while temperature rise accelerated in the past five decades. Enhanced warming alone can thus hardly explain the annual number of reported GLOFs, suggesting that temperature‐driven glacier lake formation, growth, and failure are weakly coupled, or that outbursts have been overlooked. Indeed, our analysis emphasizes a distinct geographic and temporal bias in GLOF reporting, and we project that between two to four out of five GLOFs on average might have gone unnoticed in the early to mid‐20th century. We recommend that such biases should be considered, or better corrected for, when attributing the frequency of reported GLOFs to atmospheric warming.

Glacier lake outburst floods (GLOF) are cryospheric hazards of severe destructive potential. GLOFs are prevalent in all glacierized mountain ranges globally and can cause high economic losses and pose a threat to people and livelihoods, potentially impacting agricultural land, lives and infrastructure. This underlines the importance of effective GLOF disaster risk management (DRM). GLOF DRM experiences are reported on in mountain ranges globally. However, there are relevant gaps in their documentation, analysis, and evaluation. This study compiled GLOF DRM experiences in South and North America, Europe, and Asia. We categorized the different structural and non-structural measures that have been taken and systematically analysed the temporal scope in which they function (i.e., short-term, long-term), as well as the risk component they influence (i.e., hazard, exposure, vulnerability). We analysed for the different DRM measures, in what context they were practiced, what their benefits were, what challenges were faced, as well looking at aspects of sustainability. We found that the biggest share of DRM measures is based on and applied in a limited spatial context often aiming at the reduction of a physical hazard emerging from a specific glacial lake. Examples of such activities are syphoning and pumping of lakes, drainage channels (with/out sluice gates) and tunnels for lake level regulation, flow channel adaptation, dam reinforcement, etc. Such measures, while generally taken once and aimed at short-term fixes (e.g., lake level lowering by pumping) as well as at long-term fixes (definitive lake level lowering by outflow tunnel), can face issues of sustainability. This can be the case for structural measures, for instance, when structures become unfit due to environmental changes (e.g., climate-related, earthquakes). While there are short-term as well as long-term measures in all three risk management components (hazard, exposure, vulnerability), there is a tendency for hazard reduction measures to be more short-term focused, and for exposure reduction (e.g., early warning systems, spatial planning, relocation, etc.) and vulnerability reduction (e.g., information, governance, preparedness, economic diversification, disaster relief, etc.) to be more mid- and long-term focused. Different challenges were found for all examined DRM measures mostly arising from issues in the technical feasibility (due to harsh climatic and environmental settings), the financial cost (of deploying people and material, and maintaining structures), and social acceptance and appropriation. While the findings from this study should not be generalized and strictly imposed on all other GLOF DRM cases, the knowledge gained by it is urgently needed to develop recommendations for GLOF DRM based on best practice experiences. GLOF DRM will become increasingly important in warming and increasingly exposed mountain environments globally. It will, thus, be important to further investigate the cost and benefit as well as the effectiveness of different DRM strategies. For sustainable DRM it is important to not look at GLOF hazard in isolation, but to take into account also other physical hazards in the same catchment.It should be considered within the wider context of integrated multi-hazard assessment in order to appropriately tackle/approach the interrelated effects of events that may occur simultaneously, cascadingly or cumulatively.

The polar regions experience widespread transformations, such that efficient methods are needed to monitor and understand Arctic landscape changes in response to climate warming and low-frequency, high-magnitude hydrological and geomorphological events. One example of such events, capable of causing serious landscape changes, is glacier lake outburst floods. On 6 August 2017, a flood event related to glacial lake outburst affected the Zackenberg River (NE Greenland). Here, we provided a very-high-resolution dataset representing unique time series of data captured immediately before (5 August 2017), during (6 August 2017), and after (8 August 2017) the flood. Our dataset covers a 2.1 km long distal section of the Zackenberg River. The available files comprise (1) unprocessed images captured using an unmanned aerial vehicle (UAV; https://doi.org/10.5281/zenodo.4495282, Tomczyk and Ewertowski, 2021a) and (2) results of structure-from-motion (SfM) processing (orthomosaics, digital elevation models, and hillshade models in a raster format), uncertainty assessments (precision maps), and effects of geomorphological mapping in vector formats (https://doi.org/10.5281/zenodo.4498296, Tomczyk and Ewertowski, 2021b). Potential applications of the presented dataset include (1) assessment and quantification of landscape changes as an immediate result of a glacier lake outburst flood; (2) long-term monitoring of high-Arctic river valley development (in conjunction with other datasets); (3) establishing a baseline for quantification of geomorphological impacts of future glacier lake outburst floods; (4) assessment of geohazards related to bank erosion and debris flow development (hazards for research station infrastructure – station buildings and bridge); (5) monitoring of permafrost degradation; and (6) modelling flood impacts on river ecosystem, transport capacity, and channel stability.

Abstract. The detachment of large parts of low-angle mountain glaciers, resulting in massive ice-rock avalanches, have so far been believed to be a unique type of event, made known to the global scientific community first for the 2002 Kolka Glacier detachment, Caucasus Mountains, and then for the 2016 collapses of two glaciers in the Aru range, Tibet. Since 2016, several so-far unknown glacier detachments have been discovered and described, and new ones occurred. In the current contribution, we compile, compare and discuss 19 actual or possible large-volume detachments of low-angle mountain glaciers at nine different sites in the Caucasus, the Pamirs, Tibet, Alaska’s St. Elias mountains, and the Southern Andes. Many of the detachments reached volumes in the order of 10–100 million m3. Commonalities and differences between the cases investigated suggest that a set of different conditions drives a transient combination of factors related to low basal friction, high driving stress, concentration of shear stress, and low resistance to exceed stability thresholds. Particularly, soft bedrocks below the detached glaciers seem to be a common condition among the observed events, as they offer smooth contact areas between the glacier and its substratum while being prone to till-strength weakening and eventually basal failure under high pore-water pressure. Surface slopes of the detached glaciers range between around 10° and 20°, possibly on the one hand low enough to enable development of thick and thus large-volume glaciers, and on the other hand steep enough to allow critical basal stresses to build up. Most of the ice-rock avalanches resulting from the detachments in this study have a particularly low angle of reach, down to around 0.1 (apparent friction angle), likely due to their high ice content and connected liquefaction potential, the ready availability of soft basal slurries and large amounts of basal water, and the smooth topographic setting typical for glacial valleys. Low-angle glacier detachments combine elements, and likely also physical processes of glacier surges and ice break-offs from steep glaciers. The surge-like temporal evolution ahead of several detachments or their geographic proximity to other surge-type glaciers suggests the glacier detachments investigated can be interpreted as end-members of the continuum of surge-like glacier instabilities. Though rare, glacier detachments appear more frequent than previously thought and disclose, despite local differences in conditions and precursory evolutions, the fundamental and critical potential of low-angle soft glacier beds to fail catastrophically.

The article presents the results of the work devoted to the analysis of the Sentinel-2/MSI optical images applicability for monitoring the snow cover pollution in industrial Arctic cities. Initially, the authors evaluate the accuracy of calculating the albedo values from satellite images based on the albedo ground-based measurements with a pyranometer in Moscow and Kirovsk. Statistical analysis has shown a high correlation between ground-based and satellite albedo measurements, which makes it possible to use quantitative albedo values in the spatiotemporal analysis of snow cover contamination. For three cities (Murmansk, Vorkuta, Norilsk) that differ in physical and geographical conditions and the type of industrial enterprises, the analysis of snow cover contamination for the period 2016–2020 was carried out. For Murmansk, the main pollutant is coal dust from the seaport, where coal is handled in an open way. In early 2020. the city authorities have completed the construction of a dust screen around the port terminals to reduce urban pollution. The analysis carried out in the work showed that the installed screen significantly reduced the area of pollution in the city of Murmansk. For terrain height more than 120 m, the albedo values correspond to the maximum values for the selected date, which indicates that coal dust spreads for territories located at altitudes of less than 100 m. It was not possible to identify long-term dynamics of albedo values for Vorkuta and Norilsk. Polluted snow cover is observed at a distance of up to 10 km from polluting enterprises.

Many thousands of glacier lakes have formed from glacier retreat in high mountains since the beginning of the 20th century. These water bodies are impounded by glaciers and moraines and can release sudden glacier lake outburst floods (GLOFs), with potentially disastrous downstream consequences. Estimates of GLOF frequency, magnitude, and hazard at global or regional scales remain controversial because of unsystematic reports and inconsistent regional flood databases. We compile the largest GLOF inventory to date, containing 2,000 cases (AD 1901—2018) from 700 different sources. We find that the annual number of reported GLOFs has increased more than fivefold in our study period. This increase could be due to physical reasons such as atmospheric warming or because of growing research interest in glaciers. We tested this notion by comparing annual GLOF counts with the annual number of glacier surveys and the mean annual temperature extracted from all burst lakes. Our models show that research interest in glaciers has a higher impact on GLOF reporting, suggesting that historic documentation in earlier decades was likely biased towards more accessible mountain ranges such as the European Alps. Despite improved GLOF detection, reported flood volumes and peak discharges have become smaller since the 1960s. We analysed volume changes of glaciers that dammed burst lakes, and found that these glaciers have thinned considerably in past decades. Rapidly melting glaciers may thus impound smaller lakes and produce floods of decreasing magnitudes. Using extreme-value statistics, we will investigate how GLOF return periods or return levels have changed in past decades. Our regional GLOF hazard assessment will focus on mountain ranges with increasing exposure of population and infrastructure such as the Andes, the Pacific Northwest, Iceland, the European Alps, Scandinavia, and High Asia. These estimates of GLOF hazard will provide quantitative support for practitioners to identify regions that have a high demand for strategies in GLOF risk management.

High mountain areas are prone to extreme hydrological events, and their study is especially important in the context of ongoing intensive deglaciation. In this research, a model “chain” consisting of a hydrodynamic model and a runoff formation model is adopted to simulate a glacier lake outburst flood (GLOF) from Bashkara Lake (the Central Caucasus, Russia) and its effect on downstream. In addition to an actual GLOF event that occurred on 1 September 2017 and led to casualties and significant destruction in the Adylsu and Baksan Rivers valleys, possible scenarios for the re-outburst of the lake are considered. The hydrographs of the outburst and the downstream movement of the flood wave along the Adylsu River valley are estimated using STREAM_2D two-dimensional hydrodynamic model. The water discharges in the entire river network of the Baksan River are assessed using the ECOMAG (ECOlogical Model for Applied Geophysics) runoff formation model. The output flood hydrograph from the hydrodynamic model is set as additional input into the Baksan River runoff formation model in the upper reaches of the Adylsu River. As a result of the simulations, estimates for the contribution of GLOFs and precipitation to an increase in peak discharge along the Baksan River were obtained. The actual outburst flood contributed 45% and precipitation 30% to the peak flow in the Baksan River at the mouth of the Adylsu River (10 km from the outburst site). In Tyrnyauz (40 km from the outburst site), the contributions of the outburst flood and precipitation were equal and, in Zayukovo (70 km from the outburst site), the outburst flood contributed only 20% to the peak flow, whereas precipitation contributed 44%. Similar calculations were made for future potential re-outburst flood, taking into account climatic changes with an increase in air temperatures of 2 °C, an increase in precipitation of 10% in winter and a decrease of 10% in summer. The maximum discharge of the re-outburst flood in the Adylsu River mouth, according to model estimations, will be approximately three times less than the discharge of the actual outburst on 1 September 2017 and can contribute up to 18% of the peak discharge in the Baksan River at the confluence.

The ongoing intensive deglaciation in high mountain areas is resulting in great instability of mountainous headwater regions, which could significantly extreme hydrological events In this research a model “chain” of hydrodynamic and runoff formation models is adopted to simulate a glacier lake outburst flood (GLOF) from Bashkara Lake, situated in headwater region of the Baksan River and its effect on the downstream. Two-dimensional hydrodynamic model for the Adylsu River valley was developed, based on the STREAM_2D software (author V. Belikov). The ECOMAG runoff formation model (author Yu. Motovilov) for the entire Baksan River basin was adopted. The output flood hydrograph from the STREAM_2D model was set as additional input into the Baksan River runoff formation model in the upper reaches of the Adylsu River below Bashkara and Lapa Lakes. Based on field surveys and remote sensing data, actual Bashkara Lake GLOF on September 1, 2017 was modelled. The GLOF event was triggered by extreme precipitation that caused overwetting of the dam and increase in the lake water level. The peak GLOF discharge according to modeling was estimated as 710 m3/s at the dambreak section and 320 m3/s at the Adylsu River mouth 40 minutes after the outburst. Two possible mechanisms for re-outburst of Bashkara Lake were taken into account: the rock avalanche impact, forming displacement waves, and the lake outburst due to increase in the water level, accompanied by expansion of the existing dam break. Under the rock avalanche scenario, there was no significant model response. Based on the results of modeling of the second re-outburst scenario, the maximum discharge of the outflow was estimated as 298 m3/s at the dambreak section and 101 m3/s in the Adylsu River mouth. As a result of model chain application contribution of GLOFs and precipitation to an increase in peak discharge along the Baksan River was estimated. The actual outburst flood amounted to 45% and the precipitation - to 30% of the peak flow in the Baksan River at the mouth of the Adylsu river (10 km from the outburst site). In Tyrnyauz (40 km from the outburst site) the components of the outburst flood and precipitation were equalized, and in Zayukovo (70 km from the outburst site) the outburst flood contributed only about 20% to the peak flow, whereas precipitation - 44%. Similar calculations were made for a potential re-outburst flood, taking into account expected climate changes with an increase in air temperatures by 2°С and an increase in precipitation by 10% in winter and decrease by 10% in summer. The maximum discharge of the re-outburst flood in the Adylsu river mouth according to modeling can be approximately 3 times less than discharge of the actual outburst on September 1, 2017 and can contribute up to 18% to peak discharge in the Baksan River at the confluence with the Adylsu river. The Baksan River runoff formation model was developed under support of RFBR, project number 20-35-70024. The glaciation changes and climate impact scenarios analysis was funded by RFBR and the Royal Society of London (RS), project number 21-55-10003.

Glacier mass balance is affected by non-climatic factors such as topography, debris cover and geometric parameters of glaciers themselves, avalanche activity, volcanism, etc. The contribution of snow avalanches to the snow accumulation on a glacier is still among the least studied components of the glacier’s mass balance. We propose a possible approach for the numerical assessment of snow avalanche contribution to accumulation at mountain glaciers. The approach consists on the following steps: terrain analysis; weather data analysis; snow avalanche volume assessment during an analyzed balance year; numerical simulation of snow avalanches using RAMMS; evaluation of snow avalanche contribution to glacier accumulation. The proposed methodology was tested on three glaciers (Batysh Sook, № 354, Karabatkak) with an area up to 6,5 km2 in the Inner Tien Shan and Kolka glacier with an area 1,2 km2 in the Central Caucasus. To evaluate snow avalanche contribution to the winter accumulation, we reconstructed avalanche release zones that were most probably active during the analyzed balance year and corresponding snow fracture height in each zone. The numerical simulations of most probable released snow avalanches during the analyzed year using avalanche dynamics RAMMS software were performed and compared with the field observations and UAV orthophoto images. The outlines of avalanches deposits were realistically reproduced by RAMMS according to the results of field observations. The estimated contribution of snow avalanches to the accumulation on the studied glaciers during the analyzed balance year was as follows: Batysh Sook – 7,4±2,5%; № 354 – 2,2±0,7%; Karabatkak– 10,8±3,6% of the winter mass balance. In strong contradiction to the benchmark glaciers in the Tien Shan, the Kolka glacier demonstrates rapid mass gain in the Caucasus. It might be explained by significant, up to 80% share of avalanche nourishment to glacier mass gain. We note that avalanche-fed glaciers seem to be more stable at current stage of regional warming observed both in the Caucasus and the Tian Shan. The obtained results show the importance of the non-climatic factors for glacier surface mass balance control.

On July 8, 1998, the deadliest glacier lake outburst flood (GLOF) in Central Asia for at least the last 100 years occurred in the Shakhimardan catchment, Kyrgyzstan. Most of the >100 victims were, however, killed in the Uzbek enclave of Shakhimardan, i.e. in the downstream part of this transboundary catchment. No warnings were issued between the two countries. In addition, due to political tensions, access to the site was impossible and a detailed assessment of the disaster could not be realized until now. Using remote sensing, we show that the lake at the origin of the “Shakhimardan event” appeared in the 1960s and drained periodically, without, however, causing damage to downstream areas before it eventually disappeared in the late 1980s. Based on post-event videos, we conclude that the GLOF-producing depression was again filled with a lake, estimated at 20 ± 1.2 × 103 m2 in area, before the disaster. The lake burst was likely driven by the rapidly rising air temperatures and the melting of snow/ice in late June and early July. The GLOF first travelled as a debris flow for 17 km, then continued as a debris flood in the increasingly flatter channel for another 20 km. Interestingly, the mean weighted channel angle in the areas of erosion was extremely low at 6.7°. The flood continued further downstream for ~100 km from its source. Today, 32 lakes (total area ~300 × 103 m2 in 2018) exist in the catchment, with several of the larger lakes (>5 × 103 m2) showing signs of instability. We therefore call for a systematic monitoring of environments like the Shakhimardan catchment, as well as for the installation of early warning systems at critical sites, with exchange of data between the Kyrgyz and Uzbek disaster risk management units, so as to mitigate existing and evolving GLOF risks.

Sudden large-volume detachments of low-angle mountain glaciersmore frequent than thought

The restructuring of the lower reach of the Koiavgan Creek channel (the right bank tributary of the Djankuat River) occurred on 1 July 2015 after continuous rainfall with a total precipitation amount of 227 mm. This led to the breakthrough of the Djankuat Glacier lateral moraine. The lower reach of the creek channel was initially formed at the junction of the bedrock slopes and lateral moraine and descended sharply at the end of the moraine to a wide glacial valley of the Djankuat River. The part of the channel from the end of the moraine line to the creek’s outlet in the bottom of the glacial valley had a height difference of 125 m at a distance of about 250 m. The active landslide has been recorded in the place of future breakthrough based on interpretation of 2014 summer satellite image. The linear erosion began to form on the wall of the disruption. Thermokarst processes probably also contributed to this breakthrough. The total volume of sediment eroded during the breakthrough and for four years after is 156 500 m3. The breakthrough has formed the largest sediment cone 300 meters wide and more than 200 m long in the bottom of the Djankuat River valley.

Glacier mass loss and consequent termini retreat lead to formation and growth of glacier lakes. In the Mt. Elbrus region, outbursts of lakes formed in recent decades have led to human casualties and significant damage. Building codes of Russian Federation on engineering surveys do not regulate the possibility of glacier lake formation in front of retreating glaciers, which can lead to errors in the future engineering design. Using ground based and airborne GPR data, as well as global ice thickness models, we have identified areas of potential lake formation on glacier bed for a number of glaciers in the Mt. Elbrus region. The method was tested by retrospective modeling for Bolshoy Azau and Djikiugankez glaciers bed topography on the base of 1957 topographic map. In the areas where glaciers disappeared by 2017, out of 13 simulated closed bed depressions 7 existing lakes were predicted by the hydraulic potential. 6 closed depressions on Djikiugankez glacier bed as of 1957 are currently absent, which might be related to the model uncertainties and the original DEMs errors, as well as to possible filling of lakes by sediments. Retrospective modeling of the Bashkara glacier bed topography based on SRTM DEM (2000) showed significant growth potential of the lake Lapa. Retrospective modeling of the Kaayarty glacier bed topography has not provided a clear answer about the possibility if subglacial lake outburst flood was a trigger for catastrophic debris flow formation during the summer of 2000. In case of total disappearance of Bolshoy Azau, Djikiugankez and Bashkara glaciers at least 11 new lakes with total area of about 1.7 km2 and an average depth of 8 m will form. While the deepest lake will appear in ablation zone of Bolshoy Azau glacier (at elevation 3100-3400 m a.s.l.) the largest in area (1 km2) glacial lake will be formed at the Djikiugankez snout with maximum depth of 40 m and mean depth of 7.2 m. The simulation also showed that in the present conditions, glacier bed lakes of different number and size may also exist under studied glaciers. Our estimates may contain uncertainties due to low resolution of airborne GPR data and the lack of GPR data for Kaayarty glacier, DEM and ice thickness model errors. Detailed ground-based radar survey planned for the summer 2020 will enable the assessment of the size and volume of the potential lakes under Bolshoy Azau glacier. This work was funded by RFBR grant No. 18-05-00520.