• How can we determine the formation of paleo-dams and constrain the origin, magnitude and sediment flux of paleo-GLOFs?
• What are the long-term rates and return periods of these events, and what explains their observed regional differences?
• To what degree can the frequency, intensity, duration, and impacts of individual GLOFs be attributed to natural versus anthropogenic atmospheric warming?
• How can we better incorporate the roles of triggers and preconditioning factors in flood hazard models?
• What controls the spatial variability of outburst flood hazard at local, regional, and global scales, and how will this hazard evolve as lakes respond to changing climatic conditions?
• How can flow models and risk assessments account for a dynamically changing size distribution of glacial lakes?
• What are best-practice strategies to manage risk, prevent the initiation of GLOFs, and implement early warning systems?
• How vulnerable are downstream communities and how do they perceive, and cope with, the risk from outburst floods?
We invite contributions addressing these and related challenges, spanning paleo-lake and -flood analyses; case studies; process-based modelling; susceptibility, vulnerability, hazard, and risk assessments; and projections of changes in lake abundance, size, and GLOF hazard.
The Peruvian Andes are among the world’s regions most affected by global warming, leading to rapid glacier retreat. The Cordillera Blanca (CB), the most glaciated tropical range, has lost ~41% of its glacier area since 1962. This retreat has preconditioned the formation and growth of numerous glacial lakes, increasing Glacial Lake Outburst Floods hazard and associated slope instability. The Santa River valley (western flank of the CB) is the second most exposed region worldwide to GLOFs, where steep topographic gradients favor high-magnitude floods toward downstream communities. Over the last decades, repeated catastrophic GLOFs in the Santa River valley have caused thousands of fatalities, including the 1941 Palcacocha GLOF (~1800 fatalities).
This study focuses on the Llullán and Parón valleys in the northern CB. These catchments include Laguna Parón (~60 × 10⁶ m³), considered one of the potentially dangerous glacial lakes, as well as Huandoy peak (6343 m a.s.l.). At the outlet of the Llullán valley lies an extensive fan-shaped deposit, ~4 km wide and 3 km long. The city of Caraz (~2300 m a.s.l.), with ~22,000 inhabitants, is built on this landform, where numerous very large boulders (up to 20 m in diameter) are scattered all across the surface. These features raise key questions about the magnitude and return periods of the extreme events. Our objective is to constrain the timing, magnitude, and topoclimatic conditions of the paleo-events that formed the Caraz fan deposit to assess exposure under current conditions.
Field and remote sensing observations show that the Caraz fan deposit is continuously connected to a sedimentary fill in the Llullán Valley. This surface exhibits a homogeneous longitudinal profile of ~11 km with ~5° slope, following an east–west trajectory. We inventoried hundreds of granodiorite boulders embedded across the deposit surface, which spatial and statistical distribution provide evidence of a high-energy event. Outcrops along the Santa River reveal vertical sections of a homogeneous debris-flow body characterized by subrounded granodiorite clasts (up to 5 m), some displaying jigsaw-clast structures, within a sand–gravel–silt matrix. Debris-flow run-up along the Llullán valley reached >50 m above the current riverbed, further indicating a high-energy event. The deposit ranges from 20 to 40 m in thickness, covers ~12 km², and has an estimated volume >400 × 10⁶ m³.
Twenty-four paired ages based on in-situ cosmogenic nuclide exposure dating (¹⁰Be, ²⁶Al) on eleven large boulders (including two replicates) reveal a consistent exposure history, indicating the Caraz paleo-event occurred as a single event at ~10 ka. This timing coincides with Early Holocene warming and rapid glacier retreat (horizontal velocity 4–8 km/ka) following the Younger Dryas glacial advance. We hypothesize that a paleo-lake, trapped behind the Younger Dryas moraine in the upper Parón Valley, at a location like the current Laguna Paron, may have been the source of an extreme GLOF that generated the Caraz debris-flow. Understanding the origin of the Caraz paleo-debris-flow provides key analogues to assess the hazard posed by Laguna Parón and its moraine dam, which has a volume of comparable magnitude.
How to cite: Concha, R., Zerathe, S., Lehmann, B., Carcaillet, J., Delgado, F., Gómez, D., Tórres Lázaro, J. C., Cusicanqui, D., Albinez, L., and Cosi, M.: Evidence of extreme debris flows during early Holocene glacier retreat in the Cordillera Blanca (Peru) : paleo-GLOF hypothesis and implications for current hazard, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6733, https://doi.org/10.5194/egusphere-egu26-6733, 2026.
The overall aim of this paper is to assess the present day geomorphological record of the 1967 Steinsholtshlaup in Iceland to understand better the event and the hazards it generated, its long-term legacy and the implications for both landscape interpretation and hazard planning in areas of contemporary valley glaciation. The 1967 landslide was a complex paraglacial response to decades of down wasting of the Steinsholtsjökull glacier. The rockslide incorporated glacier ice, then swept into a proglacial lake and a confined pro-glacial valley, leaving a trail of ice, rock debris and landscape transformation. About 5 km from the site of the collapse, boulders up to 80 m3 in size were scattered immediately beyond the confluence of the proglacial valley with a wide sandur. A paper published by Kjartansson in 1967 recorded the immediate aftermath of the GLOF, but left many questions unanswered, and there have been no subsequent publications.
A better understanding of this event is important because, circumstances similar to those found in the Steinsholtsdalur valley prior to 1967 have developed in numerous glacial environments around Iceland’s ice caps. As in many other mountain areas, increased temperatures over the last deccadees have driven renewed and rapid retreat of valley glaciers. Across Iceland, existing proglacial lakes have expanded, and many new ones have formed. These glacier fluctuations have affected the stability of neighbouring mountain slopes, which are resulting in slope deformation and mass movements. The potential for a major geomorphological incident in areas that both attract tourists year-round and have seen a recent related infrastructure development raise serious concerns and stresses an urgent need to study and monitor these environments.
How to cite: Sæmundsson, Þ., Wells, G., and Ben-Yehoshua, D.: The geomorphological impact of the 1967 Steinsholtshlaup Glacial Lake Outburst Flood, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10959, https://doi.org/10.5194/egusphere-egu26-10959, 2026.
Glacier lake outburst floods (GLOFs) from ice-dammed lakes in Greenland are significant hydrological events that have a far-reaching impact on downstream ecosystems, infrastructure and glacier dynamics. A notable example is Lake Tininnilik in western Greenland, which is dammed by the marine-terminating Saqqarleq Sermia. The lake has a history of rapid drainage events involving water volumes of ~1.5 km³ and sudden drops in water level of ~65 m. Glacier thinning has increased the lake's drainage frequency from ten to five years, as evidenced by the 2010 and following GLOFs. The most recent event was observed in late July 2025.
However, GLOFs at Lake Tininnilik vary considerably in timing from year to year, depending on the configuration of the ice, while the trigger factors appear to change between ice-dam flotation and increased glacier velocity. This raises questions regarding the interplay between glacier dynamics and lake drainage processes.
Here, we present a comprehensive analysis of the relationship between the recent and historical drainage behaviour of Lake Tininnilik (occurrence, frequency and volume) and the configuration of the ice (particularly velocity and thickness) by combining time series of remotely sensed lake and ice parameters.
As part of the LIDL (Linking Ice-Dammed Lake Drainage to Ice Dynamics in Greenland) project, our aim is to apply the developed analysis framework to a wide range of ice-dammed lakes in Greenland exhibiting GLOF behaviour. Our goal is to gain a broader understanding of the role of ice flow dynamics, particularly ice thickness and velocity, in modulating and potentially initiating drainage events. This will contribute to improved GLOF prediction in a changing climate.
How to cite: Köhler, J. and Kjeldsen, K.: Linking GLOFs at ice-dammed lakes in Greenland to ice configuration: The case of Lake Tininnilik, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5448, https://doi.org/10.5194/egusphere-egu26-5448, 2026.
Using an ensemble of diverse data sources, including digital elevation models, lake bathymetry, mass balance records, historic texts, and regional meteorological records, we present a detailed assessment of glacier geometry and Glacier Lake Outburst Flood (GLOF) mechanism changes. The analysis focuses on GLOFs documented over the past 200 years at Nedre Demmevatn, an ice-dammed lake formed by the outlet glacier Rembesdalskåka of Hardangerjøkulen, Norway.
Our results reveal variability in glacier extent, with pronounced thinning over the past 25 years. This accelerated thinning coincides with the near-annual recurrence of outburst floods since 2014. Hydrograph data from the past decade, characterized by rapid glacier melt, indicate a shift in outburst mechanisms from overspill, partial flotation, and channel enlargement to predominantly channel enlargement. We propose that this transition is driven by seasonal temperature fluctuations, evolving lake bathymetry, and progressive thinning of the ice dam.
In total, we document 26 GLOF events over two centuries. Historical records indicate that drainage mechanisms in the 1900s alternated between supraglacial overspill and partial ice uplift with channel enlargement. The former occurred predominantly during periods of glacier advance, while the latter was more common during phases of glacier retreat, often accompanied by a reduction in ice velocity. The study reveals a link between evolving bathymetry, drainage mechanisms and glacier responses to climate warming. This knowledge is important for communities and infrastructure near rapidly changing glaciers, supporting effective adaptive strategies.
How to cite: Enzenhofer, U., Schytt Mannerfelt, E., Andreassen, L. M., Elvehøy, H., and Nixon, C.: Two Centuries of Ice-dammed Glacier Lake Outburst Floods at Rembesdalskåka, Norway., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18899, https://doi.org/10.5194/egusphere-egu26-18899, 2026.
The Tête Rousse glacier, located in the Mont Blanc massif (French Alps), is a polythermal glacier that hosts a water pocket in the center that has been identified and monitored since around 2008 [1,2]. Despite repeated artificial pumping operations aimed at draining this cavity, it continues to retain water and is therefore subject to regular monitoring, notably through piezometric pressure measurements, Nuclear Magnetic Resonance (NMR) surveys and ground-penetrating radar profiles. This water storage may develop into catastrophic glacial lake outburst floods (GLOF), threatening infrastructures and human lives downstream.
A seismic ambient noise campaign conducted in 2022 [3] revealed anomalies the upper part of the glacier, suggesting the presence of a second water reservoir with undefined contours. The NMR survey of 2023 confirmed the presence of around 50,000 m3 of liquid water beneath the upstream part of the glacier. However, additional GPR profiles and drillings have have left significant uncertainties about this new reservoir.
In August 2025, numerous concentric cracks were observed in the upstream sector of the glacier. On 10 August 2025, eyewitnesses reported abnormal activity in the glacier's outlet stream for several hours. The presence of piezometric sensors within the glacier, combined with recordings from a seismic sensor located at its centre, made it possible to accurately reconstruct the chronology of the drainage. Beginning on 9 August, a progressive increase in anomalous microseismic activity was observed, culminating in a main event of seismic magnitude 0. Subsequently, piezometric levels exhibited a two-stage evolution: first, water flowed from the upstream part to the central cavity; second, drainage proceeded from the central cavity toward the downstream part of the glacier. These hydrological transfers were confirmed by a second seismic proxy, namely variations in seismic background noise levels. Following the drainage event, abnormal elevated microseismic activity was observed for several weeks, reflecting the collapse of drained areas and the ongoing brittle deformation within the glacier, including the development of surface cracks.
These observations suggest that seismological monitoring and piezometric measurements constitute complementary and effective tools for understanding the dynamics of glacial water pocket drainage. Moreover, they provide several precursor and early-warning signals that could be used for monitoring strategies and operational alert systems aimed at mitigating this type of glacial hazard.
References:
[1] Vincent, C., Descloitres, M., Garambois, S., Legchenko, A., Guyard, H., & Gilbert, A. (2012). Detection of a subglacial lake in glacier de Tête
Rousse (Mont Blanc area, France). Journal of Glaciology, 58(211), 866–878.
[2] Vincent, C., Garambois, S., Thibert, E., Lefèbvre, E., Meur, E. L., & Six, D. (2010). Origin of the outburst flood from glacier de Tête Rousse in
1892 (Mont Blanc area, France). Journal of Glaciology, 56(198), 688–698.
[3] A. Guillemot, N. Bontemps, E. Larose, D. Teodor, S. Faller, L. Baillet, S. Garambois, E. Thibert, O. Gagliardini, C. Vincent : Investigating Subglacial Water-filled Cavities by Spectral Analysis of Ambient Seismic Noise : Results on the Polythermal Tête-Rousse Glacier (Mont Blanc, France), Geophys. Res. Lett. 51 e2023GL105038 (2024).
How to cite: Larose, E., Kokowski, J., Gagliardini, O., Thibert, E., Brondex, J., Garambois, S., Bonnefoy, M., Buffet, A., Arnaud, L., Laarman, O., and Camus, B.: Seismic and piezometric signature of the natural drainage of the Tête Rousse glacier, august 9th 2025, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10127, https://doi.org/10.5194/egusphere-egu26-10127, 2026.
There is a clear link between global warming and the increase in glacier melting, leading to the expansion of glacial lakes, often dammed by fragile moraines. Triggers such as heavy rainfall, earthquakes, landslides, avalanches, glacier breakoffs, or thawing permafrost can cause glacial lake outburst floods (GLOFs). These events result in moraine breaches, releasing flood waves of mud and debris that can cause significant damage and endanger populations. On August 16, 2024, a GLOF from the Thyanbo glacial lakes affected the village Thame, Nepal. This flood caused destruction of the local infrastructure, buildings and agricultural land, and displaced over 135 inhabitants. According to first investigations, it seems that an initial trigger originated from the upper glacial lake and overtopped its terminal moraine. This flood wave further ran into the lower glacial lake, which overtopped the terminal moraine and caused it to breach. All mentioned cascading incidents triggered the GLOF running downstream. As no in situ data is available, we used high-resolution optical as well as Synthetic Aperture Radar (SAR) remote sensing data to map the lakes dynamics and measured the ground deformations at the terminal moraines. To date, such analyses have been applied only to glacial lakes and terminal moraines without documented GLOF events, but not to systems affected by a previously occurred GLOF.
High-resolution PlanetScope multispectral images from 2019 to 2024 showed an expansion of the upper lake by 213.3 % before the event, followed by a loss of 25.9 %, while the lower lake just increased slightly by 2.8 % over the timeseries, but lost over 74.3 % of its area during the GLOF. The analysis showed that the upper terminal moraine has not eroded at all or only very slightly, whereas the lower moraine has largely eroded. Consequently, while the lower lake no longer represents a future hazard, the upper lake continues to pose a high risk.
SAR Sentinel-1 images from 2020 to 2024 were used to perform a Persistent Scatterer Interferometry (PSI) with the Stanford Method of Persistent Scatterers (StaMPS). By combining ascending and descending orbits, the vertical and horizontal movements of the resulting scatterers were deconstructed. As the GLOF was likely triggered by an external factor, no abrupt movements were detected in advance by the PSI. Nevertheless, significantly stronger vertical and horizontal subsidence was observed at the lower terminal moraine, reflecting its greater exposure to the GLOF relative to the upper moraine. The analysis demonstrated that, with certain improvements, remote-sensing data combined with PSI can be used to assess the overall stability of terminal moraines and enable meaningful comparisons between them.
Based on this case study, the methodology will be transferred to a regional approach in the Himalayas in a future study to contribute to a more comprehensive inventory of potentially dangerous glacial lakes by adding the parameter of terminal moraine stability, which has not yet been considered in depth.
How to cite: Dedring, N., Rienow, A., and Graw, V.: Persistent Scatterer Interferometry for early detection of Glacial Lake Outburst Floods: A case study of the 2024 Thyanbo GLOF near Thame, Nepal, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13179, https://doi.org/10.5194/egusphere-egu26-13179, 2026.
Rapid retreat of glaciers due to global warming has led to the expansion of glacial lakes, heightening the risk of glacial lake outburst floods (GLOFs), which pose severe threats to lives and infrastructure in downstream regions. In the Sikkim Himalaya, the Gurudongmar Lake Complex (GLC) consists of four lakes holding approximately 148 × 10⁶ m³ of water, with an enlargement rate of 74 ± 3%. This study integrates a two-dimensional erosion-based moraine-dam breach model using TELEMAC 2D and SISYPHE with one-dimensional inundation modelling in HEC-RAS to assess the impacts of multi-lake GLOFs under varying scenarios. Simulations based on remote sensing and field data revealed that in the most extreme case – an 80% overtopping breach – peak flood discharges could reach up to 8882.0 m³/s, releasing a total water volume of 59.4 × 10⁶ m³. Flood heights under these scenarios could significantly exceed those observed during the South Lhonak GLOF event of October 2023, intensifying risks for downstream communities. The assessment of 19 settlement sites using a 15×15 m fishnet revealed that Thangu Valley and Chungthang town are most vulnerable, with potential inundation levels and infrastructure exposure highest in these areas. Combined breaches, such as the sequential failure of lakes GL-2 and GL-1 or GL-3 and GL-1, further amplify the flood risk, underscoring the complex dynamics of multi-lake outbursts. This research provides critical insights into moraine-dam erosion processes and downstream flood impacts, offering a robust framework for hazard mitigation in the Eastern Himalayas and similar glacierized terrains worldwide.
Keywords: Glacial lake outburst floods (GLOFs); Erosion dam breach model; Hydrodynamic flood modelling; HEC-RAS; Exposure assessment; Sikkim.
How to cite: Chowdhury, A., Begam, S., Kroczek, T., Vilímek, V., Sharma, M. C., and De, S. K.: Modelling Erosional Dam Breach & Downstream Flood Exposure from Cascading Multi-Glacial Lake Outburst Processes in the Eastern Himalayas, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13968, https://doi.org/10.5194/egusphere-egu26-13968, 2026.
The Juncal catchment, located in the Valparaíso Region, Central Andes of Chile, hosts 79 glaciers, including Monos de Agua and Juncal Norte glaciers. The latter has an active glaciological monitoring at least since 2020, which has allowed an accurate assessment of its recent evolution. On a regular basis, research at this site has focused on the hydrological significance both to the Region and for the Aconcagua River. Nonetheless, glacier hazards have received less attention, posing an opportunity for new studies.
In this contribution, we present the chronological evolution of three glacial lakes that originated in the Juncal catchment: (1) Juncal Norte Glacier (DGA code CL105400072A) proglacial lake, at 2,940 m a.s.l.; (2) proglacial lake 077, located in front of the CL105400077 Glacier at 3,560 m a.s.l., and (3) glacial lake 088, associated with the rock glacier CL105400088, at 4,055 m a.s.l., which is currently drained.
Through the analysis of Sentinel-2 and PlanetScope imagery, we determined that these lakes formed at the end of the 2018 boreal summer, whilst their expansion is still ongoing. By the end of 2025 summer, the extension of Juncal Norte and 077 glacial lakes reached 4 and 2 ha, respectively, whereas the 088 lake would have reached a maximum extension of 2.1 ha by May 2023. Our results show that the 088 glacial lake drainage began at the start of the summer of 2024, ending by February 2024. Special attention is given to the 077 glacial lake’s expansion, which is confined by the glacier’s frontal moraine, and is located 800 m above the river drained from the Juncal Norte Glacier. Such a condition is critical in the scenario of a GLOF, due to the high potential energy involved in an eventual outburst.
The morphological heterogeneity of these glacial lakes, combined with their location and the particular characteristics of the glaciers that originate them, poses important challenges for field surveys and the precise evaluation of the GLOF hazard assessment within the Juncal catchment.
How to cite: Ugalde, F., Carrion, D., Fernandoy, F., and Muñoz, L.: Glacial lakes at the Juncal catchment, Chilean Central Andes: origin, evolution and GLOF hazard management challenges, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14396, https://doi.org/10.5194/egusphere-egu26-14396, 2026.
The last ca. 10 years have seen a particularly strong proliferation of research around glacier lake outburst floods (GLOF), with the number of corresponding peer-reviewed publications hitting 100 per year most recently.
Major progress has been made, and debates have developed, around the number, volume and change of glacial lakes, and the frequency of GLOF’s over time and the relation to glacier shrinkage and climate change, globally and in particular regions such as High Mountain Asia. Hazard and risk assessments have been performed widely, ranging from local to global scale, and against a range of climatic and socio-economic future scenarios. Major GLOF events and disasters such as the 2023 South Lhonak GLOF, have been carefully analyzed with an objective to better understand physical processes and impacts. GLOF’s are increasingly sketched as cascading processes, and thus posing important challenges to process understanding, modeling and forecast. A range of models have been applied to GLOF processes, from physically based models for local scale to simpler models at regional scale but important challenges remain.
Against this impressive progress in GLOF research, we identify and discuss here critical fields that have not yet received sufficient attention but have important scientific or societal relevance, or represent research areas where progress is facing important challenges and barriers. Specifically, we identify four core frontiers in GLOF research and risk management:
(1) Location and dynamics of hazard sources: recent cases have shown that GLOF’s often originate from poorly or unknown, or rapidly changing sources, thus posing a major issue for comprehensive hazard and risk analysis.
(2) Probability of occurrence of GLOF’s and GLOF-triggering mass movements such as rock / ice avalanches. Limited research has addressed this issue, and if, typically remained at a qualitative level. Quantification, however, will prove to be essential for areas such as climate litigation cases, for advancing probabilistic hazard and risk assessments, and as a basis for establishing risk transfer mechanisms like insurances.
(3) Several events have shown the eminent importance of sediment entrainment and flow dynamics for the impact of GLOF’s on population and infrastructure, but many challenges remain in terms of process understanding, modelling and assessment methods.
(4) Effectiveness of risk management and climate change adaptation for GLOFs: quite a range of disaster risk reduction measures for GLOF’s are recognized and global experiences have been recently comprehensively analyzed. However, as we further move into a rapidly changing high-mountain landscape, and public finance is increasingly stressed, the assessment of effectiveness and limits of risk management option against different levels of warming and related GLOF scenarios becomes more and more urgent.
We will elaborate how GLOF research can address these frontiers and what it may entail in terms of international cooperation.
How to cite: Huggel, C., Allen, S., Frey, H., Miles, E., and Niggli, L.: Frontiers in GLOF research and risk management, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7114, https://doi.org/10.5194/egusphere-egu26-7114, 2026.
Around Greenland more than 3300 lakes intersect with the ice sheet margin and act as natural buffer for freshwater runoff from the Greenland Ice Sheet (GrIS). More than 300 of those lakes have been identified as having drained in the past or to drain periodically. These glacial lake outburst floods (GLOFs) strongly affect the fjord ecosystem due to the large amount of freshwater abruptly entering the saline ocean environment. By draining underneath glaciers, these events affect glacier dynamics. Specifically, they can increase glacier flow velocities due to hydrostatic pressure and reduced friction at the glacier bed, permanently change the subglacial drainage system and trigger calving events due to the formation of subglacial plumes.
While the existence of these GLOF type lakes has been reported, a Greenland wide assessment of the timing, periodicity and lake volume is lacking. Here we present such an assessment conducted by leveraging open-source data, specifically Sentinel-1 radar images and the ArcticDEM strip elevation data. In Sentinel-1 radar data, water is distinguishable from other surfaces due to its characteristically low backscatter intensity. Therefore, any change in lake extent will be reflected in a change of the backscatter signal. For the 10-year period 2016-2025 and for each GLOF type lake, we create a time-series of the mean backscatter intensity over the approximate maximum lake outline. Subsequently, we detect drainages where the backscatter signal abruptly increases and stays elevated. To quantify the volume of each lake drainage, we first outline pre and post lake extents. Then, we extract the lake level by intersecting these outlines with a DEM of the lake at an empty stage. Finally, we convert lake level change to lake drainage volume by filling the DEM to the respective elevations.
We find that many lakes follow a pattern of lake drainage in the summer followed by refilling through ice sheet runoff in the following year(s). The duration of drainage cycles varies between yearly to decadal. A longer filling period is usually also associated with a larger GLOF volume. The GLOF volumes are among the largest ever reported with a magnitude of several gigatons. Furthermore, we show that the combined GLOF volumes modulate the runoff pattern of the GrIS. The runoff is buffered by filling these lakes and eventually released at a later point in time. The changing of the seasonality of freshwater reaching the ocean potentially has widespread impacts on fjord and ocean circulation, which are not captured in regional climate and ocean models.
How to cite: Vacek, F., Nick, F. M., Vries, A., Immerzeel, W., and van de Wal, R. S. W.: Timing and volume of glacial lake outburst floods in Greenland, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18261, https://doi.org/10.5194/egusphere-egu26-18261, 2026.
While the influence of long-term climatic warming on glacier lake outburst floods (GLOF) occurrence is well-documented, the role of short-term meteorological conditions in influencing the precise timing of individual outburst events remains poorly understood. This gap is particularly evident in the Scandinavian region, where only few studies have examined how variability in temperature, precipitation, and melt conditions during days and weeks prior to an outburst flood may influence the timing of GLOF events. Therefore, this study aims to systematically investigate the relationship between the short-term variability in key meteorological variables and the timing of mostly ice-dammed GLOF events in Norway. Of the 112 documented GLOF events in Norway between 1979 and 2025, only 83 were selected for further analysis, as precise event dates were not available for all documented outburst floods. Meteorological variables for all individual GLOF events were extracted using the NORA3 dataset, a reanalysis product provided by the Norwegian Meteorological Institute. Time windows of 60, 30, 15, 7, and 3 days prior to each event were defined to assess short-term changes in meteorological conditions leading up to the outburst floods. The analysis shows no clear general relationship between precipitation and timing of GLOF events. However, in a few cases, intense precipitation immediately prior to the outburst may have acted as a triggering factor. Regarding temperature development prior to the outburst events across different time windows, the analysis revealed an inverse relationship: Significant warming trends are more prevalent over longer periods preceding an outburst, whereas shorter-term windows are dominated by non-significant or negative temperature trends. A quite similar pattern was observed regarding the change of the mean average temperatures across the different time windows. Comparing the 7 days immediately prior to an outburst with the preceding 60 days, mean temperatures were higher in 66.3 % of events. In contrast, when considering the 3 days prior compared to the preceding 30 days, only 49.4 % of events were warmer. These findings suggest that short-term warming immediately before GLOFs does not follow a consistent pattern. Regarding total water input (melt and precipitation), the analysis shows no evidence of a systematic short-term increase immediately prior to outbursts. While longer periods (e.g., 15 days) preceding events often had higher cumulative input compared to earlier intervals, the proportion of events with higher input decreased for shorter time windows. Furthermore, snow cover at the glacier margins was analyzed using satellite data, revealing that the majority (54%) of glaciers remained snow-covered both before and after the outburst events. The analysis shows that no single trigger can be identified in most cases, but that a minimum amount of meltwater input combined with short-term cooling may be a combination of conditions that frequently precedes outburst floods at ice-dammed lakes in Norway.
How to cite: Haas, F., Egli, P., Kusch, E., Rodari, L., and Andreassen, L.: Assessing the relationship between short-term meteorological variability and the timing of GLOFs in Norway based on 83 documented events, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21113, https://doi.org/10.5194/egusphere-egu26-21113, 2026.
Outbursts from ice-dammed lakes typically recur through cycles of filling and are driven by complex drainage mechanisms that can influence the magnitude and the timings of the Glacial Lake Outburst Flood (GLOF). Predicting GLOFs from ice-dammed lakes is complex, because ice dams are formed by an active glacier that is constantly changing in response to climate. New approaches combining numerical modelling, AI-driven models and remote sensing can be used to understand these protean hazards. This study combines subglacial modelling (using GlaDS within Elmer/Ice) with novel field data to enhance the understanding of physical processes during outburst flood events from an ice-dammed lake in Norway. This aim fits within the larger CryoSCOPE project that seeks to integrate machine-learning with physics-based numerical models and remote-sensing observations to improve the assessment of cryospheric hazards. The study glacier is Rembesdalskåka, the largest outlet glacier of Hardangerjøkulen ice cap in southern Norway and the source of Norway's most destructive GLOFs in 1893 and 1937. The glacier was monitored over the last 50 years, making an ideal case study to improve understanding of these complex processes at place. We will present field observations from 2025, and the data inputs for the modelling of GLOFs between 2023 and 2026 as a first step towards understanding the exact sequence of events and interplay of processes that drives GLOF-events at Rembesdalskåka.
How to cite: Rodari, L., Egli, P. E., Cook, S., Zwinger, T., and Rowan, A. V.: Toward modelling glacier lake outburst floods from ice-dammed lakes: case study in Rembesdalskåka, Norway, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8068, https://doi.org/10.5194/egusphere-egu26-8068, 2026.
Glacier motion, retreat, and hazards like surges and glacial lake outburst floods (GLOF) are strongly affected by subglacial hydrology. In High Mountain Asia, surges and GLOF, which have caused billions in damages in recent decades, occur in the context of increasingly negative mass loss, erratic weather patterns, and dwindling water resources. While surges and GLOF have generally been studied separately, observations at surge-type glaciers in the Karakoram Range of Pakistan exhibit identical patterns of concurrent surge termination and GLOF, implying that both phenomena may be connected to changes in subglacial hydrology. Here, we build on previous modeling work with SHAKTI (Subglacial Hydrology and Kinetic, Transient Interactions) that demonstrated that seasonal subglacial hydrology alone is insufficient to explain observed velocity changes. We use a coupled subglacial hydrology and ice dynamics framework to investigate how ice-dammed lake outbursts affect the motion of surging glaciers. We then demonstrate the effects of lake bathymetry and glacier geometry on flood characteristics and ice motion.
How to cite: Narayanan, N., Chu, W., Sommers, A., Meyer, C., Steiner, J., and Minchew, B.: Investigating Relationships between Lake Drainages and Surge Motion through Modeling in the Karakoram Himalaya, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2857, https://doi.org/10.5194/egusphere-egu26-2857, 2026.
Glaciers in the Karakoram range are known to surge periodically, often triggering glacial lake outburst floods (GLOFs). However, the Shyok Valley remains comparatively understudied in this context. This study examines the surge dynamics of five glaciers- Aktash, Kichik Kumden, Chong Kumden, South Rimo-X, and Central Rimo, in the upper Shyok Valley of the Eastern Karakoram range, mapping their movements and the formation of associated lakes caused by ice-dammed river blockages. Between 1996 and 2025, three distinct lake sites formed. Two of these lakes filled and drained multiple times, while the third filled and drained only once. In total, six major outburst events and several minor drainage events were identified, including multiple previously undocumented events. While glacier surging is generally understood to follow cyclical behaviour, no consistent recurrence interval was observed in this study. Notably, GLOF locations were found to repeat, driven by the same glaciers periodically surging and obstructing the same river channels. The estimated lake volumes are comparable to those of known GLOF-producing lakes in the western Karakoram. These glaciers pose notable flood hazards due to their potential for large-scale ice dam formation and subsequent outbursts. Overall, this study contributes to further understanding of glacier surge dynamics in the eastern Karakoram, the GLOF hazards they pose and the likelihood of these events repeating.
How to cite: Rifky, A.: From Surge to Flood: GLOF Hazards Linked to Glacier Surges in the Upper Shyok Valley , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1172, https://doi.org/10.5194/egusphere-egu26-1172, 2026.
Subaerial lakes dammed by glacier ice have a long history of scientific and public interest, as they can drain catastrophically in outburst floods (jökulhlaups) and refill repeatedly. The hazard associated with this jökulhlaup cycle may persist for decades to centuries through a cascade of processes that includes ice-dam flotation, enlargement of a subglacial drainage tunnel, and its partial or complete resealing after the flood. Theory suggests that both the height and climate-driven decay of the ice dam fundamentally control the frequency and magnitude of jökulhlaups during this cycle: thinning and retreat of the dam may lower pre-outburst lake levels and flood volumes, while reduced lake accommodation space could allow drainage events to occur more frequently, potentially several times within a single year.
Given that glacier dams have been losing elevation at accelerating rates over recent decades, I hypothesize that the jökulhlaup cycle may intensify, leading to a faster-than-linear decrease in outburst flood magnitude accompanied by an increase in jökulhlaup frequency. Testing this hypothesis has so far been constrained by sampling biases and gaps in historical flood records. Here, I present results from manual mapping of pre-outburst lake areas for at least 71 ice-dammed lakes that drained at least ten times between 1984 and 2025 in northwestern North America, Patagonia, Iceland, Scandinavia, the European Alps, and High Mountain Asia. Using optical satellite imagery from Landsat, Sentinel-2, and Planet, I systematically reconstruct jökulhlaup time series to assess decadal trends in pre-outburst lake area and drainage frequency. I fit linear and quadratic models with potential change points to test for gradual or abrupt acceleration in the jökulhlaup cycle.
Preliminary results indicate that >75% of lakes in the sample currently exhibit declining pre-jökulhlaup areas, with 15% showing evidence for an accelerated decrease in outburst magnitude. In approximately one quarter of all cases, the models favour breakpoint behaviour, with increasing pre-jökulhlaup lake areas prior to a subsequent decline. Notably, 22% of lakes have not yet reached this peak and instead show ongoing increases in pre-outburst surface area. Most of these lakes formed during the study period and actively erode their ice dams, shifting the lake toward the dam and enlarging their own basin area. This process enables lakes to buffer even high local rates of dam thinning and helps identify locations where deglaciation may favour increasing hazard, contrary to the global trend. Furthermore, only about one third of lakes show a trend toward more frequent outbursts. For most lakes, drainage frequency remains unchanged—most commonly at one event per year—consistent with the idea that subglacial tunnel systems close slowly after drainage, inhibiting multiple outbursts within a single year. Overall, the prevalence of declining outburst magnitudes occurring at largely unchanged frequencies suggests that, at the global scale, the hazard posed by ice-dammed lakes has been declining over the past four decades.
How to cite: Veh, G.: Smaller but not more frequent: assessing decadal trends in jökulhlaup cycle , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19116, https://doi.org/10.5194/egusphere-egu26-19116, 2026.
The Warwan sub-basin in Jammu and Kashmir is a remote glaciated basin that harbors several glacial lakes and has also been showing development in terms of infrastructure and population. This sub-basin witnessed several mass movement events in the past, including avalanches and GLOF that remained unreported. This study investigates past mass movement events in the Warwan sub-basin, Jammu and Kashmir, Western Himalaya. Three major avalanche events occurred in the last two decades. The September 2005 and September 2020 avalanches occurred from glaciers GL-B and GL-A, respectively, in the same glacier complex. The March 2020 event was a rock-ice avalanche that originated from the headwall of the glacier (GL-F) located in the valley opposite the glacier complex. The avalanche terminated before reaching the ablation zone of the glacier. Mapping of the avalanche runouts revealed that the September 2020 ice avalanche initiated from the headwall of the glacier (GL-A), impacting the lake located at its terminus, causing downstream GLOF. The runout of the September 2005 rock-ice avalanche terminated before reaching the terminus, where a glacial lake started forming in 1999. Evaluation of the geomorphic processes in the glacier complex shows sediment influx through meltwater stream of GL-D and GL-E into the lake associated with GL-A. This sediment influx led to infill of the lake basin. Further retreat of GL-A led to meltwater accumulation behind the sediment infill, creating two disconnected lakes in the same lake basin. The September 2020 avalanche impacted this lake-basin, leading to complete drainage of the infill sediment and water, causing downstream debris flow. Pre and post-GLOF imagery show that the outflow channel of the lake breached, leading to channel widening. The major GLOF outwash debris formed a prominent debris fan immediately downstream of the lake. The GLOF water discharge drained into the downstream lake (GL-B), resulting in a GLOF cascade. The study highlights how GLOF events and avalanche occurrences remain unreported due to downstream cascading processes and remote locations. The study highlights how GLOF events and avalanche occurrences may remain unreported in remote locations, possibly resulting in the underestimation of a threat for downstream areas. The history of mass movement events and the growth of the glacial lakes and GLOFs in the Warwan sub-basin call for monitoring and risk assessment considering changing conditions in future.
EGUsphere preprint: https://doi.org/10.5194/egusphere-2025-6281
How to cite: Sattar, A., Rai, S. K., Emmer, A., Dhar, S., and Haritashya, U.: Geomorphic processes of unreported GLOF cascade and past avalanches, Jammu and Kashmir, Western Himalaya, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16390, https://doi.org/10.5194/egusphere-egu26-16390, 2026.
Glacial retreat in the Himalayas has led to more frequent glacial lake outburst floods (GLOFs), which often pose serious transboundary threats. On July 8, 2025, a GLOF occurred in the Donglin Zangbo Basin near Gyirong Port, triggering a large-scale debris flow across the China-Nepal border. Due to the lack of field data in this remote area, we reconstructed the disaster process using multi-source remote sensing and high-resolution Gaofen-7 (GF-7) terrain data. Our analysis shows the lake expanded rapidly to 0.6 km2. By establishing a water level–area–capacity (L-A-V) relationship, the total storage was estimated at 8.0-8.5 × 106 m3, with a released volume of 5.0-6.0 × 106 m3. Based on remote sensing-derived breach morphology, the peak discharge was calculated at 1100-1400 m3, showing high consistency with downstream hydrological records. Notably, a distinct discrepancy between the estimated outburst volume and downstream flood hydrographs suggests complex subglacial hydrological mechanisms, specifically the "bulking effect" caused by intense sediment entrainment and potential englacial drainage. These findings underscore the non-linear amplification of GLOF disaster chains and demonstrate the indispensable value of remote sensing in hazard assessment.
How to cite: Li, X., Zhang, H., Mu, J., Song, W., Yang, Y., and Chai, F.: Remote Sensing Reconstruction and Mechanism Analysis of the July 2025 Glacial Lake Outburst Flood (GLOF) at the Gyirong Port, China-Nepal Border , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11346, https://doi.org/10.5194/egusphere-egu26-11346, 2026.
Glacier retreat is projected to continue with future climate warming, expanding proglacial lakes and increasing the risk of mass movement events such as landslides or rock falls. If a mass movement enters a lake, it may generate a displacement wave or glacial lake outburst flood (GLOF), which can significantly modify landscapes and threaten communities and infrastructure downstream.
Mass movement-triggered GLOFs pose an emerging yet understudied hazard in Iceland. One such site is Sólheimajökull, an outlet glacier of the Mýrdalsjökull ice cap in south Iceland that is one of the country’s most visited spots for glacier hikes and lake tours. This study presents results from new field surveys of lake bathymetry and subglacial topography to: 1) report lake volume evolution from 2009 to 2023; 2) project future lake development scenarios under continued glacier retreat; and 3) identify areas with high topographic potential of sourcing mass movements that could trigger a GLOF.
Sólheimajökull’s proglacial lake has grown significantly since it began to form around 2007, covering ~0.45 km2 by 2023. If the glacier terminus continues to retreat, the lake will expand into an overdeepened trough, roughly doubling its maximum depth, quadrupling its surface area, and increasing its volume by a factor of nine. If recent retreat rates continue, Sólheimajökull’s terminus could enter the deepest part of the trough in approximately a decade and retreat out of the lake basin within a century, though this could occur more quickly if calving rates increase due to deeper water. The estimated maximum lake extent will reach ~4 km up-valley from its current location, extending beneath several zones of the valley walls with high topographic potential of sourcing a rock fall or avalanche that could trigger a GLOF. This has significant implications for future glacier access, tourism planning, infrastructure development, and visitor risk exposure. These results can inform hazard mitigation strategies at Sólheimajökull, as well as guide studies of this emerging hazard at other proglacial lakes in Iceland.
How to cite: Wells, G., Sæmundsson, Þ., Magnússon, E., Aðalgeirsdóttir, G., and Pálsson, F.: Glacial lake development and outburst flood hazard at Sólheimajökull glacier, Iceland, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13281, https://doi.org/10.5194/egusphere-egu26-13281, 2026.
Glacial lake outburst floods (GLOFs) originating from breaches of moraine-dammed lakes represent serious risk in high mountain regions around the world, as recently exemplified by the 2023 South Lhonak GLOF. Informed disaster risk reduction requires reliable modelling inputs. While computational capacities and modelling tools improved greatly in past years, some of the key input parameters remain poorly addressed. Among these, the estimation of realistic potential flood volume represents a major challenge. To bridge this gap, we compiled a dataset of breached moraine-dammed outbursts and calculated mean slope of the breached channel after the GLOF, as it can be used to approximate breach depth / lake level drop and so volume. The mean slope of the breached channels in the dataset varies from 2.3° (Q0) to 19.5° (Q4), while Q1 is 3.1° and Q3 is 6.6° while the median (Q2) is 5.0° and the mean is 5.5°. We found that a little change in slope of the breached channel changes estimated potential flood volume substantially, especially in cases of rather flat wide dams, suggesting high sensitivity of predictive GLOF modelling studies to this parameter.
EGUsphere preprint: https://doi.org/10.5194/egusphere-2025-4136
How to cite: Emmer, A., Sattar, A., and Hrebrina, J.: The slope of the breached channel controls potential flood volume of moraine-dammed lake outbursts, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16497, https://doi.org/10.5194/egusphere-egu26-16497, 2026.
This study demonstrates the potential of cost-effective sonar integrated with uncrewed surface vehicles (USVs) for bathymetric surveys of high-altitude mountain lakes in the northwestern Himalaya, India. Three lakes were selected as test sites, Deepak Tal (3,770 m), Suraj Tal (4,777 m) near Baralacha La in Lahaul & Spiti, Himachal Pradesh, and a smaller lake near Parashar Lake (hereafter referred to as NP Lake; 2,592 m) in Mandi, Himachal Pradesh, India. The surveys were conducted using a Deeper Pro+ sonar mounted on a USV. The sonar recorded depth measurements at individual points, which were later interpolated using Kriging to generate continuous bathymetric surfaces for each lake.
For Deepak Tal, over 25,000 depth points were collected, yielding a maximum depth of 7.44 m and an estimated lake volume of 41,929.05 m³. For Suraj Tal, more than 5,000 points were acquired, with a maximum depth of 2.56 m and a corresponding volume of 9,400.95 m³. For NP Lake, approximately 1,000 points were recorded, with a maximum depth of ~1.3 m and a volume of 2,947.53 m³. Several empirical formulas were applied to calculate volume of the lakes and compared with the field-derived volumes, revealing extremely large deviations (up to ~129,908 times), highlighting the limitations of the empirical formulas used for volume estimation of high-altitude lakes.
Overall, this study demonstrates that the Deeper Pro+ sonar mounted on a USV provides an effective, low-cost, and low-risk approach for generating high-resolution bathymetry, accurate volume estimates, and detailed morphometric information for high-mountain lakes.
Keywords: Cost-Effective Bathymetry; High-Altitude Lakes; USV; Sonar Mapping; Lake Volume; Northwestern Himalaya
How to cite: Pathak, B., Singh, A., Dhiman, N., Mahanta, K. K., and Shukla, Dr. D. P.: Low-Cost Sonar-Based Bathymetry for Morphometric Analysis of Himalayan High-Altitude Lakes, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16489, https://doi.org/10.5194/egusphere-egu26-16489, 2026.
The mountain cryosphere is rapidly changing in the 21st century. Glacier mass loss is accelerating, permafrost is thawing, and precipitation falls increasingly as rain. These are fundamental changes to the hydrological functioning of high mountain catchments, including throughput and storage. There has been focused attention on the progressive development of large glacial lakes, due to their high visibility and impacts in the case of an outburst flood. Satellite-based monitoring of such sites is a relatively straightforward task, yet effective evaluation and early warning of hazards remains challenging, as it must take into account site specific considerations, the possible chains of geomorphic processes, and implementation challenges for technical, logistical, and community ownership aspects. In recent years, however, outburst floods have increasingly occurred originating not from known large proglacial lakes, but from glacial and periglacial lakes that have developed on subseasonal timescales of weeks to months. The development of water bodies over these short timescales is often entirely unnoticed before a flood; as a result, these events have caused significant damage and fatalities, as evidenced in at least 8 distinct events in 2025. Early detection of these emergent water bodies is essential and requires a rapid-repeat operational tool that is reliable and insensitive to meteorological conditions.
In this work we develop a framework for rapid identification of anomalous water bodies using Sentinel-1 GRD data in Google Earth Engine. Sentinel-1 is frequently used in inundation mapping efforts due to the low radar backscatter of water, its cloud penetration, and short temporal revisit (6 days for 1A and 1B combined). However, the SAR data present specific challenges: distinct ascending and descending view geometries, difficulties in geocoding due to mountain terrain and glacier thinning, an uncertain backscatter threshold for lake detection, and confounding signals of wet snow, soil moisture, or seasonal vegetation development. Rather than attempting to map lakes directly, we overcome these challenges by instead identifying domains with an anomalous signal that is also consistent with water. Specifically, we determine the anomaly of the latest backscatter data to historic backscatter phenology in each pixel, expressed as a composite z-score for the ascending and descending orbits, and mapped only in domains where radar backscatter and topographic slope are both low.
We implement this approach in our tool THAW (Transient Hydrologic Anomalies Weekly) and demonstrate its operational utility by examining the detections that would have occurred preceding the Purepu (Tibet/Nepal) and Rawoshan (Pakistan) events in 2025. In both cases, THAW identified an anomalous signal likely to indicate surface water weeks and months prior to the lakes’ drainage. The approach is not sensitive to seasonally wet snow, as it accounts for the location’s typical seasonality, but highlights the early seasonal melt of Himalayan snowpacks in 2025. Our tests at Purepu identified the growth of another lake at Nyanang Phu (Tibet), enabling an early in-situ assessment by authorities. We find this framework to complement operational lake monitoring workflows by highlighting selected domains of rapid change for expert evaluation.
How to cite: Miles, E., Fugger, S., Allen, S., Steiner, J., and Huggel, C.: Early detection of emergent high-mountain lakes using Sentinel-1, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16809, https://doi.org/10.5194/egusphere-egu26-16809, 2026.
Posters virtual: Tue, 5 May, 14:00–18:00 | vPoster spot 1a
EGU26-11635 | ECS | Posters virtual | VPS20
Monitoring post-GLOF moraine dynamics at South Lhonak lake using satellite radarsTue, 05 May, 14:00–14:03 (CEST) vPoster spot 1a
The South Lhonak Lake (SLL) Glacial Lake Outburst Flood (GLOF) cascade event of 3-4 October 2023 triggered widespread devastation across Sikkim and the downstream region of Bangladesh, causing significant loss of lives and property. The post-disaster research shows that the GLOF event was triggered by a moraine failure, creating tsunami waves in the lake, eventually leading to the breach of the frontal moraine. Despite partial drainage of the lake in the 2023 event, the hazard potential of the lake needs further investigation. This makes it extremely important to continuously monitor the surrounding regions to identify unstable slopes that can potentially fail and impact the lake. The present study utilises a Sentinel-1 Small Baseline Subset (SBAS) workflow performed in the ASF OpenSARLab environment to analyse the condition of the moraines post-SLL disaster. Post-disaster analysis spanning October 2023 to September 2025 reveals continued moraine instability, characterised by an actively deforming zone along the right flank of the failed zone. This region shows a maximum LOS displacement rate of approximately -4 cm yr-1, with a maximum cumulative LOS displacement reaching around -6 cm in the ascending track and -5 cm in the descending track. The results indicate persistent post-failure deformation and ongoing slope instability in the moraines of South Lhonak. The study provides a critical insight into the temporal behaviour of moraine slopes. This study aimed at strengthening the disaster management strategies by integrating satellite-based deformation monitoring for early warning and risk reduction measures.
How to cite: Verma, U. and Sattar, A.: Monitoring post-GLOF moraine dynamics at South Lhonak lake using satellite radars, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11635, https://doi.org/10.5194/egusphere-egu26-11635, 2026.
EGU26-17889 | ECS | Posters virtual | VPS20
Evolution of present and potential future glacial lakes and implications for GLOF hazard in the Chenab Basin, Western HimalayaTue, 05 May, 14:03–14:06 (CEST) vPoster spot 1a
Accelerated glacier retreat in the Western Himalaya has led to rapid expansion of glacial lakes and increasing concern over Glacial Lake Outburst Flood (GLOF) hazards. This study presents a basin-scale assessment of glacial lake evolution, potential future lake formation, and GLOF susceptibility in the Chenab Basin, integrating multi-temporal remote sensing, terrain analysis, and probabilistic exposure modelling. A decadal inventory of glacial lakes was developed for five time periods (1990, 2000, 2010, 2020 and 2025) using Landsat and Sentinel-2 imagery, combined with semi-automated extraction and geomorphological classification. Results reveal a consistent increase in both lake number and total area over the last three decades. Potential future glacial lakes were identified using various ice-thickness modeling approach applied to current glacier extents. This analysis presents an inventory of the future glacial lake in the entire basin giving special emphasis to determining the characteristics of the future lake including maximum extent of the future lakes and volume of the future glacial lakes. GLOF susceptibility of existing lakes was evaluated using a multi-criteria framework to identify critical lakes requiring priority monitoring. Downstream exposure was further assessed using the Monte Carlo Least Cost path approach, explicitly accounting for uncertainty in breach location and flood routing parameters to delineate probable impact corridors. The framework provides new insights into evolving cryospheric hazards in the Chenab Basin and demonstrates the utility of combining lake dynamics, future lake potential, susceptibility assessment, and probabilistic exposure analysis for improved GLOF risk prioritization in the Western Himalayas.
How to cite: Das, D. R. and Sattar, A.: Evolution of present and potential future glacial lakes and implications for GLOF hazard in the Chenab Basin, Western Himalaya, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17889, https://doi.org/10.5194/egusphere-egu26-17889, 2026.
EGU26-5669 | ECS | Posters virtual | VPS20
Impact of climatic warming on glacier surges and associated ice-dammed lake outburst floods in the Eastern KarakoramTue, 05 May, 14:06–14:09 (CEST) vPoster spot 1a
The Karakoram is known for its numerous surge glaciers and associated hazards from ice-dammed lake outburst floods. However, significant discrepancies persist in our understanding of surge trends and flood frequency. Therefore, this study aims to clarify the surge behaviour and related glacial lake outburst flood (GLOF) history for the Kumdan group of glaciers (Chong Kumdan, Kichik Kumdan, and Aktash). The study analysed historical archives, high-resolution satellite imagery, elevation changes derived from digital elevation models (DEMs), and glacier surface velocity from the ITS_LIVE dataset. Based on an in-depth review of historical records and cross-verified with multi-temporal satellite imagery, 16 GLOFs have been documented from this group since 1835, primarily originating from Chong Kumdan and Kichik Kumdan. The Aktash Glacier has surged several times but has not formed any ice-dammed lake due to efficient subglacial drainage, which prevents river blockages. Chong Kumdan and Aktash glaciers exhibit longer active phases (~7-10 years), whereas Kichik Kumdan Glacier shows shorter phases (~2 years). Out of all three Kumdan glaciers, the Chong Kumdan has produced the most devastating floods in 1835, 1926 and 1929. This glacier comprises two tributaries (a and b) and main trunk. Tributary ‘a’ follows a ~77-year surge cycle, and tributary ‘b’ and the main trunk exhibit asynchronous surge records. The surge cycle duration of Kichik Kumdan Glacier decreased from 33 years (1833–1866) to 27 years (1970–1997) due to climate warming. The last GLOFs from Chong Kumdan and Kichik Kumdan occurred in 1934 and 1903, respectively. DEM analysis from 2015 to 2022 reveals thickening in the reservoir areas of Chong Kumdan (~22 m) and Kichik Kumdan (~20 m), suggesting potential future surge but with a low probability of GLOF events. Overall, our study observed a decline in surge-generated GLOFs due to climate warming, reduced mass accumulation and weakening of ice dams. These insights will help downstream communities and risk management authorities better understand future risks and develop effective mitigation strategies.
How to cite: Halder, S. and Bhambri, R.: Impact of climatic warming on glacier surges and associated ice-dammed lake outburst floods in the Eastern Karakoram, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5669, https://doi.org/10.5194/egusphere-egu26-5669, 2026.
EGU26-1083 | ECS | Posters virtual | VPS20
Glacial lakes in permafrost terrain and downstream hazardsTue, 05 May, 15:00–15:03 (CEST) vPoster spot 1a
A permafrost probability index (PPI) based on rock glacier inventory and machine learning models, including random forest, support vector machine, artificial neural network, and logistic regression, was generated for Kinnaur district, Himachal Pradesh, India. Intact rock glaciers were considered the dependent variable, and elevation, slope, aspect, and potential incoming solar radiation were used as independent variables to generate a spatially distributed, high-resolution permafrost probability index. Daily weather station data and daily multitemporal MODIS satellite data were used to train a linear regression model to predict the annual 0℃ isotherm in the region for the period of 2023-24, aiming to understand potential degradation by overlaying the isotherm on permafrost distribution. The random forest technique produced the best results with an overall accuracy of 89.43%. Seven glacial lakes were identified as located in potentially permafrost-degraded slopes, and the Kashang glacial lake was selected for detailed downstream glacial lake outburst flood process chain modeling based on its size, moraine-dammed proglacial setting, and potential downstream impact. The volume of the lake was estimated to be 8.6 × 106 m3 by extrapolating the contours from overdeepening of the main glacier. Three sources of avalanches were identified based on permafrost degradation and slopes greater than 30 degrees. Subsequently, three scenario-based process chains for glacial lake outburst floods were modeled. We simulate avalanche initialization, displacement wave generation, overtopping, moraine erosion, and downstream flooding. The modelling results revealed that the potential GLOF can cause a peak discharge of 16,167 ms⁻¹, and floodwater can reach the Kashang, where a hydropower is located, within 16 minutes in the high-magnitude scenario. The findings can give important insights into GLOF hazard mitigation in the valley and can aid as preliminary data for various stakeholders working towards mitigating glacier-related hazards.
Keywords: Permafrost, GLOF, machine learning, r.avaflow, Himalaya
How to cite: Alangadan, A. and Sattar, A.: Glacial lakes in permafrost terrain and downstream hazards, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1083, https://doi.org/10.5194/egusphere-egu26-1083, 2026.
