CR3.4

This paper presents the results from fieldwork conducted in three focal areas of the “Nunataryuk” EU H2020 permafrost project: the Nordic Area (Greenland and Svalbard), the Beaufort Sea Area in Canada (Northwest Territories/ Inuvialuit Settlement Region and Gwich’in First Nation Traditional Territory) and Northeastern Siberia in Russia. The paper analyzes the entanglement between social and environmental change and presents a risk analysis framework, including the interconnected geo-physical & socio-cultural risks, with the aim to improve adaptation and mitigation strategies of local communities. Guided by a mixed-methods approach, the research outcomes are the result of field-based research, including focus groups, qualitative interviews, participant observation, community workshops – as well as a quantitative survey in three settlements (Qeqertarsuaq in Greenland, Aklavik in Canada and Longyearbyen on Svalbard).

How to cite: Gartler, S., Larsen, J. N., Ingimundarson, J. H., Schweitzer, P., Povoroznyuk, O., and Meyer, A.: A risk analysis framework: Key risks from permafrost thaw in Arctic coastal areas, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7937, https://doi.org/10.5194/egusphere-egu22-7937, 2022.

Infrastructure and anthropogenic impacts are expanding across the Arctic. A consistent record of human impact is required in order to quantify the changes and to assess climate change impacts on the communities.
We derived a first panarctic satellite-based record of expanding infrastructure and anthropogenic impacts along all permafrost affected coasts (100 km buffer) within the H2020 project Nunataryuk based on Sentinel-1/2 satellite imagery. C-band synthetic aperture radar and multi-spectral information is combined through a machine learning framework. Depending on region, we identified up to 50% more information (human presence) than in OpenStreetMap. The combination with satellite records on vegetation change (specifically NDVI from Landsat since 2000) allowed quantification of recent expansion of infrastructure. Most of the expanded human presence occurred in Russia related predominantly to oil/gas industry.

The majority of areas with human presence in this coastal zone will be subject to thaw by mid-21st century based on ground temperature trends derived from the ESA CCI+ Permafrost time series (1997-2019). Of specific concern in this context are also settlements located directly at permafrost affected coasts. An efficient erosion rate monitoring scheme needs to be developed and combined with settlement records and permafrost information in order to assess the risk for local communities and infrastructure. Relevant progress in the framework of the ESA EO4PAC project will be discussed.

How to cite: Bartsch, A., Widhalm, B., Pointner, G., von Baeckmann, C., Nitze, I., Grosse, G., Lantuit, H., Irrgang, A., Boike, J., and Vieira, G.: Where is Arctic coastal infrastructure at risk?, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9094, https://doi.org/10.5194/egusphere-egu22-9094, 2022.

High-mountain regions are very sensitive to climatic changes, which is particularly visible in the drastic retreat of Alpine glaciers. Concomitant with retreating glaciers, permafrost degradation affects large parts of high-mountain regions. In recent years, the hydrological significance of permafrost ice has therefore increasingly come into focus. However, surprisingly little is known about the current state and size of water resources in alpine permafrost. Moreover, it remains unknown whether the thawing of permafrost is already making a significant contribution to late summer runoff in alpine catchments.

In this study we combine UAV-derived volumetric change detection with the hydro-chemical analysis of δ18O and δ2H isotope signatures and the radio nuclide ¹²⁹I in the discharge from the Kaiserberg rock glacier in the Austrian Alps. The combination of these methods allows a direct and indirect quantification of permafrost degradation. Furthermore, the isotopic signatures help to decipher the relative and absolute permafrost contribution to discharge over the summer months.

First results from the analysis of digital elevation models show an average volume loss of several thousand cubic metres per year between 2017 and 2019. In addition, geochemical data on δ¹⁸O- and δ²H-isotopes and the radionuclide ¹²⁹I indicate an increased contribution of meltwater from the permafrost body of the Kaiserberg rock glacier in the summer months, which is dominant on single days in late summer. 

How to cite: Kraushaar, S. and Bloethe, J. H.: Towards deciphering the contribution of permafrost and active layer to summer runoff in a small alpine catchment, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7052, https://doi.org/10.5194/egusphere-egu22-7052, 2022.

The Grandes Jorasses Massif culminates at 4203m at the Punta Walker summit on the border between France and Italy. The south slope of Grandes Jorasses is widely glaciated and overlies the Val Ferret, a populated and highly frequented area presenting different hamlets, the most important being Planpincieux village. Located at an altitude between 4000 and 4100 m, the Whymper Serac is a hanging glacier that undergoes periodic gravity-driven instabilities. On 1^st June of 1998, 150.000m³ of ice fell, and the resulting ice avalanche reached 1750m, at a distance of about 400m from houses of the Le Pont village and the main road. The monitoring activity started in 1997: a  series of boreholes had been drilled to assess the basal thermal regime of the serac and subsequently install a monitoring system for early warning signs and risk assessment

In September 2020, three thermistor chains in three different boreholes were installed on Whymper Serac. Temperature profiles were measured at different periods between October and November 2020. In September 2021 another three thermistor chains were installed and their temperature profile measured in October 2021. During the same survey, temperature profiles of the 2020 thermistors could be measured again on 2 out of 3 boreholes, (one being too close to the serac front was not safe to reach) confirming data acquired on the 2020 field campaign. The outcome of basal temperature measurements of 2020 and 2021 give good spatial coverage of the serac allowing comparison with data from the 1997 measurements, despite on the fact that most of the ice mass fell in 1998.

A warming trend in most of the temperature profiles is evident in comparison whith 1997 data; 5 out of 6 points of measure still show temperatures below 0° C. One point of measure shows evidence of temperate ice at the ice/bedrock interface. Whymper Serac measurements provide evidence that the glacier is still frozen to the bedrock, but one part of the serac shows the beginning of a potential transition from cold based regime to temperate based regime. If, on one hand, surface displacements of the ice mass still show low displacements (typical of a cold based glacier), on the other hand, a velocity anomaly was detected on a small portion of the serac corresponding to the temperate based sector. Further research is needed to better understand the evolution of the thermo-mechanical conditions of the Whymper Serac in the current climate change scenarios. Therefore, thermo-mechanical modeling of the Whymper Serac is underway, based on the Elmer/Ice model.

How to cite: Troilo, F., Paolo, P., Gottardelli, S., Mondardini, L., Giordan, D., Dematteis, N., Piard, L., Gagliardini, O., Gilbert, A., and Vincent, C.: Basal thermal regime investigations at Whymper hanging Glacier (Aosta Valley – Italy), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7208, https://doi.org/10.5194/egusphere-egu22-7208, 2022.

Forward simulations of ice avalanches are important to inform risk management. However, the reliability of such simulations often suffers from the dependency of model parameters on the process magnitude, hampering the simulation of unprecedented events in a given area. We suggest a reliable, straightforward and practically applicable work flow for the forward simulation of ice avalanches for the purpose of risk management with regard to the Planpincieux glacier, located on the Italian side of Mont Blanc massif.

Since 2013, the Planpincieux glacier, has been studied to analyse the dynamics of ice collapses in a temperate glacier. Several documented ice avalanches and glacial floods (1929, 1952, 1982, 2005, 2017), which, in some cases, threatened the village of Planpincieux and damaged the municipal road, have been linked to this glacier. Starting from the summer of 2019, a fast moving ice volume, partially separated by the rest of the glacier tongue by a large crevasse, has drastically increased the occurrence of a new collapse with possible implications for the valley floor. Considering the potential risk, a glacier constant monitoring (GbInSAR) and an avalanche early warning system (avalanche Doppler radar) were deployed, and numerical modelling of ice avalanches from this glacier was made.

Thereby, we couple an empirical-statistical model with a physically-based mass flow model: (I) the rules of Alean (1985) for the angle of reach are fed into the software r.randomwalk in order to estimate worst-case reference travel distances for various scenarios of starting volumes, (II) the basal friction angle used in the physically-based tool r.avaflow is optimized against those reference travel distances for each volume scenario, (III) the travel distances and travel times are checked for plausibility against well-documented events, (IV) flow pressures and flow kinetic energies are computed with r.avaflow for each volume scenario.

The model results are well supported by empirical data for smaller events, whereas direct reference data for the larger scenarios are not available. Interpretation of the results further has to take into account that (A) for some scenarios, the empirical relationships had to be extended beyond their known range of validity, introducing additional uncertainty, and (B) the relationships do not work for snow-covered trajectories, that, for example, would decrease the friction and lead to longer travel distances. As a result, the outcomes can be, with some care, considered as worst-case assumptions for ice avalanches in summer, but are not valid for ice avalanches during the other seasons.

How to cite: Perret, P., Mergili, M., Gottardelli, S., Mondardini, L., Segor, V., and Troilo, F.: Numerical modelling of ice avalanches from the Planpincieux glacier (Italy), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7327, https://doi.org/10.5194/egusphere-egu22-7327, 2022.

The mountain cryosphere is currently undergoing substantial modifications in an unprecedented short period of time. As effects of climate change becomes important, understanding the glacier and periglacial dynamics that lead to complex and delayed responses is timely. The spatial and functional interactions between landforms within these environments may strongly influence their processes (e.g., ablation, accumulation), usually studied in two separate research paths (i.e., glaciology and geomorphology). Very little research has focused on glacial and periglacial systems, where several perennial cryospheric elements (debris-covered glaciers, rock glaciers) are intertwined.

Here, a multidisciplinary approach is proposed combining (i) Structure from Motion on historical, modern aerial images and spaceborne images, (ii) geophysical with Electrical Resistivity Tomograms , and (iii) geomorphological surveys. The purpose is to quantify and describe morphometric changes over seven decades (1940 - 2020) at the Chauvet glacial and periglacial system (Southern French Alps, 44.85°N, 6.84°E). This study site is critical in terms of natural hazards because at least six Glacier Lake Outburst Floods were recorded during the 20^th and 21^th centuries, likely related to the permafrost degradation, the presence of a thermokarstic lake and an englacial conduit within the ice.

Complex spatio-temporal patterns and functional interactions between different landforms were evidenced. In the upper part of the valley, a small debris-free glacier turns downvalley into a debris-covered glacier occupying most of the central part of the valley. Further downslope, a rock glacier developed. The contrasting developments and landform responses are documented with multi-temporal DEMs and ortho-images. Very low thinning rates and surface velocities (< 0.5 m a^-1) were observed on the rock glacier, whereas the adjacent debris-covered glacier presents intermediate thickness losses (> 1 m a^-1) and higher surface velocities. However, the contact zone between the dead debris-covered and the rock glacier shows clear signs of mass down-wasting and complex interplay of phenomena such as thermokarst melting of massive ice and the flow towards the topographic depression.

An important speed-up of the horizontal displacements since the 1990s and an important surface lowering have most probably conditioned the dynamics of the observed outburst-floods. Those seem to be a complex combination of several processes affecting the different cryospheric elements. (i) the well-developed thermokarst lake over debris-covered area, on the topographic depression (i.e., bucket shape with barriers damming the lake) which is mainly controlled by the bedrock morphology and evolution of the surface topography. The current capacity of this depression has been estimated to 180,000 ± 350 m³. (ii) the specific glacio-geomorphological dynamics of debris-covered and the rock glacier units, which dynamics influence the opening/enlargement and closure of the englacial conduit. (iii) the hydro-meteorological conditions (e.g., enhanced snow melt in late spring) probably impacts the hydrology, water filling and the lake outflow.

The findings of this study highlight the relationships between glacial and periglacial features and their long-term evolution. The systemic study of GLOF formation processes would lead to a better identification of sites at risk and to the implementation of more robust prevention procedures in order to face the environmental and societal challenges of climate change.

How to cite: Cusicanqui, D., Bodin, X., Rabatel, A., Duvillard, P. A., Revil, A., Schoeniech, P., and Berthet, J.: Glacier-permafrost interactions and GLOF’s. Insights from 7 decades of kinematics and elevation changes in the Southern French Alps., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7659, https://doi.org/10.5194/egusphere-egu22-7659, 2022.

This study focuses on Lake Sulzenau, where a Glacial Lake Outburst Flood (GLOF), involving a partial moraine-dam breach, hit the valley in August 2017 and damaged the water supply infrastructure of a nearby mountain hut. Located in the Stubai Alps (Tyrol, Austria), the Sulzenau Lake is continuously evolving due to the rapid retreat of the Sulzenauferner Glacier. The objective of this study was to use multi-source remote sensing data (optical and radar imagery, close-range and ground-based data) to obtain a detailed overview of the whole valley, to monitor the dynamics of lake evolution since its first appearance in the early 2000s, and to characterize the conditions that led to the sudden failure of the dam and its impacts. First, we used optical images (e.g.: Sentinel-2, Google Earth) to produce two detailed geomorphological maps (pre- and post-event) of Lake Sulzenau and its surroundings to identify, describe and quantify the impacts of the 2017 event on the local geomorphology. Secondly, based on multi-temporal Digital Elevation Models (DEMs), we analyzed the changes in the topography for several periods before and after the 2017 event. This step was supported by the construction of a recent DEM from Unmanned Aerial Vehicle (UAV) data collected during a field campaign completed in August 2021. The DEM differencing revealed vertical changes (erosion and deposition) in GLOF-affected areas. The Sulzenau Valley is a perfect example of the current dynamics of glacial environments under global warming. The GLOF of 2017, associated with the rapid retreat of the glacier and the recent growth of its lake, represents an excellent case study to better understand these natural hazards.

How to cite: Piroton, V., Emmer, A., Schlögel, R., Mergili, M., and Havenith, H.-B.: Understanding the preconditioning and driving factors of the 2017 glacial lake outburst flood in the Sulzenau valley, Tyrol, Austria, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8596, https://doi.org/10.5194/egusphere-egu22-8596, 2022.

The rock/ice avalanches that occurred in Switzerland (Piz Cengalo, 23.8.2017) and the Indian Himalaya (Chamoli, 7.2.2021) and their subsequent debris flows have highlighted the question of how much water can be generated by frictional melting of glacier ice and entrained snow. The Piz Cengalo event initiated with the release of some 3.2 mio m³ of rock and entrainment of approximately 0.6 mio m³ of glacier ice.  The source of water necessary to trigger the debris flow activity has been attributed in part to frictional melting of ice.  First calculations by Shugar et al. (2017) indicate that the Chamoli event initiated with a total of 27 mio m3 of rock (80% by volume) and glacier ice (20%). Additional entrainment of snow increased the total ice content of the flow.  Meltwater generated by frictional melting has likewise been suggested as the cause of the catastrophic flood wave.

In order to analyze the the Piz Cengalo event, the SLF developed a mathematical model to simulate rock/ice avalanches, including snow, water and soil entrainment (Margreth and Bartelt, 2018).  The model calculates the internal heat energies of the rock, ice and water phases and includes the melting of ice.  Frictional work drives the melting process, but is additionally supplemented by heat exchanges/contact between the rock-ice-water components. The model correctly provides the overall temperature rise of an event, which can be found from simple energy arguments. The numerical model, however, predicts the rate of melting, which depends on when ice and snow are entrained into the flow, as well as terrain features, which influence frictional work rates.   An important result of the model calculations is that meltwater is not spread homogeneously over the depositions, but is concentrated at specific locations in the deposits, facilitating the formation of secondary mass movements.

Using this mathematical model to simulate the Chamoli event we find a total maximum meltwater production of 2.5mio m³ to 3.0 mio m³.  This estimate should not be characterized as small:  during the flow in the upper reaches of the Raunthi Gadhera frictional heating generated 50’000 tons of water every second.  This rate decreased significantly as the flow reached the Dhauliganga river valley.    In the end, only half of the initial glacier ice melted.  From downstream gauge station measurements, Indian government officials have estimated the total volume of the water surge to be approximately 6 mio m³ over a period of one hour (Rautela et al., 2021).  In agreement with the field observations of Rautela and co-authors we find the remaining 3mio m³ of water to come from entrainment of ponded water in the Raunthi Gadhera valley and the subsequent blockage and dam break at the Dhauliganga river inlet.  That is, secondary sources of water are necessary to reproduce the observations.  A similar result is found for the Piz Cengalo case study.  Under extreme assumptions, we find that of the initial 0.6 mio m³ of glacier ice, between 0.08 mio m³ and 0.12 mio m³ melted, leaving significant amounts of ice in the depositions.  

How to cite: Bartelt, P., Munch, J., Yves, B., and Margreth, S.: The Role of Frictional Melting in Rock/Ice Avalanche Dynamics:  Thermomechanical Modelling of the Piz Cengalo and Chamoli Events, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4674, https://doi.org/10.5194/egusphere-egu22-4674, 2022.

Climate change is affecting the environment of Central Asia, the high mountains and particularly the paraglacial and glacial environments. Trends shown to affect the state and dynamics of glaciation; a gradual decrease in both area and volume, and the increase in the area of moraine deposits can be observed. Meanwhile, the frequency of occurrence of hazardous geological phenomena's related to glacial dynamics, such as outbursts of glacial lakes (GLOF'S), avalanches, rockfalls, blockages of river channels, as well as mudflows, is increasing. Observations after them are complicated by the inaccessibility of areas due to lack of infrastructure, seasonal restrictions, the required number of people to conduct observations in the field and financial costs. Studies shown that remote sensing technologies allow observation of changes and proved to have sufficient spatial and temporal resolution to assess the transformations taking place. In our study, we propose a method for assessing statistically significant changes occurring in the catchment for each of the image elements (pixel) over time using nonparametric statistics. The novelty of the work is the application of an assessment of the significance of these changes that allows to reduce the influence of human error in the analysis of images thus producing higher quality results and reducing time required. Although the technology is known in the world - and is used to solve the problems of machine learning and deep vision. For the territory of Uzbekistan and in this research area, this method is innovative, and the statistical assessment of significance over time is used for the first time. Thus, the method makes it possible to identify areas where significant changes have occurred due to events mentioned above, and reduces the amount of time and costs required to search for these areas to prevent or reduce further damage.

How to cite: Sabitov, T., Petrov, M., Mamirov, H., Akbarov, F., Suvonqulov, S., and Sabitova, N.: Tracking mountain geohazards in Uzbekistan with application of remote sensing and advances in data analysis., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3113, https://doi.org/10.5194/egusphere-egu22-3113, 2022.

Glacial lakes are an important component of terrestrial meltwater storage and respond to climate change and glacier retreat. Although there is evidence of rapid worldwide growth of glacial lakes, changes in frequency and magnitude of glacier lake outburst floods (GLOFs) under climatic changes are not yet understood. We refine existing methods of water mapping, based on optical remote sensing images, that can be applicable for the mapping of glacial lakes. We propose and discuss methods for regional-scale glacial lake mapping and GLOF detection using large time series of optical satellite images and the cloud processing tool Google Earth Engine in a semi-automatic way. The methods are presented for various temporal scales, from the 2-week Landsat revisit period to annual resolution. The proposed methods show how constructing an annual composite of pixel values such as minimum or maximum values can help to overcome traditional problems associated with water mapping from optical satellite data like clouds, or terrain and cloud shadows. For annual-resolution glacial lake mapping, our method set only involves two different band ratios based on multispectral satellite images. The elevation range, computed from a digital elevation model is used on the postprocessing step to filter out noise associated with image quality and misclassifications. The study demonstrates various examples of how the proposed methods can be applied to detect GLOFs and to produce a complete regional-scale glacial lake inventory, using the Greater Caucasus as an example. We also discuss limitations of the approaches, finding that for applications where reliable detailed maps are required, visual revision of the results is still recommended owing to the often small size of glacial lakes, combined with their large variability in, for example, topographic setting, turbidity, depth, or temporal occurrence.

How to cite: Bazilova, V. and Kääb, A. M.: Mapping glacial lakes and their changes using cloud processing of optical satellite images, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4384, https://doi.org/10.5194/egusphere-egu22-4384, 2022.

More than 90 % of territory of Kyrgyz Republic are mountains.  More than two thousand lakes have formed but only some lakes pose a threat to lives, assets and livelihoods. Many of these lakes are seasonally dynamic, and form in ice-rich permafrost environments that are characteristic of the region. The objective of this study was to describe and implement an evidence-based expert lake hazard assessment criteria, to produce an updated inventory of hazardous lakes, which are susceptible to outburst within the territory of Kyrgyz Republic. A total of 368 lakes susceptible to outburst in Kyrgyzstan were inventoried and classified into 5 classes: ice-dammed, ice-cored moraine-dammed, ice-free moraine dammed, bedrock-dammed and moraine- dammed, and landslide-dammed lakes. The hazardous lake inventory was most recently updated in 2021 based on field works and remote sensing analysis.

All 368 lakes were described by a number of quantitative and qualitative characteristics and were assigned different levels of outburst susceptibility. All studied lakes are situated within the elevational zone between 1200 m.a.s.l. and 4300 m.a.s.l. All lakes were estimated in terms of their surface area from remote sensing data for different years, which ranges from thousands to millions of square meters. For 47 ice cored moraine dammed lakes bathymetry measurements were conducted, for many of them several times.

The outburst susceptibility was estimated according to 4 hazard categories and each lake is assigned within a certain category depending on current lake characteristics. A particular feature of the non-stationary lakes found in this region is the rapid changes in outburst susceptibility that can occur over short time-periods. A total of 111 lakes, which at least once have been assigned with the highest hazard levels (the 1^st or 2^nd category) in the period from 2006-2017 were analyzed for their changes over time. According to the analysis, the hazard level of many lakes varies over time and the number of category 1 and 2 lakes has considerably decreased in the recent decade. Lakes of the 1^st and 2^nd hazard categories decreased since 2006 by 57 % and 45 % respectively (from 21 to 9 and 49 to 27), while the number of lakes of the 3^rd and 4^th categories increased from 35 to 58 and 1 to 16.

The lake hazard assessment scheme developed for the Kyrgyz Republic may be a valuable tool for scientists and authorities dealing with outburst flood hazards in other similar environments of Central Asia and elsewhere.

How to cite: Erokhin, S., Zaginaev, V., Allen, S., and Meleshko, A.: Assessment and inventory of hazardous mountain lakes in Kyrgyz Republic, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4864, https://doi.org/10.5194/egusphere-egu22-4864, 2022.

In contrast to glaciers in other areas of the world, the Karakoram glaciers appear to be stable or increasing mass in response to global climate change, a phenomenon known as the 'Karakoram anomaly.' Many glaciers are experiencing irregular, frequent, and rapid frontal advances (surges), which cause natural hazards by obstructing river channels forming ice-dammed lakes, consequent outburst floods and posing threats downstream over the region. Predicting the phenomenon to protect downstream communities remains challenging around the globe. The determination of the surge characteristics, timing and evolution of lakes and GLOFs is fundamental to flood control and disaster management. This study documents 179 glacial lake outburst floods (GLOFs) that occurred from 1533 to 2020 in five major valleys. Sixty-four of the events took place after 1970, and 37 of these had remote sensing imagery that covered the GLOF formation to breaching sequence. Thirty-six glaciers were associated with GLOFS due to ice-front advance building ice barriers in rivers. The Kayger and Khurdopin glaciers are the most hazardous examples, responsible for 31.8% of major GLOFs in the Karakoram. Using a cross-correlation feature-tracking technique on remote sensing imagery, we analyzed ten surge glaciers and documented six surge events from 1990 to 2019. Results show periodic surge cycles for the Khurdopin, Kyager, Shishper, and Chilinji glaciers of c. 15–20 years, with a surge velocity in the mid-2010s higher than that of the late 1990s for all studied glaciers. The higher velocity of a glacier increases the risk of flooding downstream of the terminus because the transfer of a huge ice mass towards the terminus during the surge is a key factor for conduit development, formation and reformation of a series of ice-dammed lakes, thus determining the magnitude and frequency of outburst flood events. The response of Karakorum glaciers to global warming and climate forcing, comprising a continuum of glacier mass gain, ice thinning, and ice advance has resulted in lake formation and ice dam failures. We predict the frequency of GLOFs will increase in the future. These findings support the increasing anomalous behavior of glaciers in the Karakoram region. A conceptual model of ice-dammed lake formation and GLOF initiation in response to glacier surging is presented to synthesize the detailed observations.

How to cite: Bazai, N., Cui, P., Carling, P., Wang, H., and Hassan, J.: Increasing the episodic glacial lake outburst flood hazard in response to surge glaciers in the Karakoram, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-752, https://doi.org/10.5194/egusphere-egu22-752, 2022.

Worst-case scenarios concerning volumes and hydrographs of sudden, far-reaching  impact/flood waves from existing and future glacial lakes are based on assumed impacts from large, high-energy rock- or rock/ice-avalanches. The probability of occurrence related to such events as a basis for quantitative hazard and risk assessment and intercomparison depends on their expected magnitude and frequency. Magnitude is given by the term “large”  - here defined as volumes of millions of m³ which enable near-instantaneous displacement of lake volumes in the order of millions to tens of millions of m³. Quantitative determination of related frequencies, on the other hand, faces fundamental difficulties for a number of reasons. Rock-ice avalanches are non-repetitive events: Once an event has occurred it cannot occur again in the same way from the exact same site, because the unstable rock mass has definitely been removed from its detachment zone. Destabilisation processes which precede rock- or rock/ice avalanches are cumulative processes: Under conditions of continued global warming, future conditions are not only different from the past, but also from present-day situations. Scenarios of drastic and long-term future glacier vanishing and permafrost degradation/thaw must be taken into consideration, along with changes in atmospheric triggering conditions.

During the past years, first steps towards producing a useful statistical data basis have been achieved concerning regional developments in time of rock- and rock/ice avalanches for selected cold mountain areas of variable sizes. The existing statistical data bases together with indications about effects from warming trends can now be used to rougly determine event recurrence times per unit area of steep icy peaks. This, in turn, opens the possibility to quantitatively estimate expected probabilities of occurrence related to possible future extreme impacts on critical locations, such as involving glacial lakes and process cascades. In view of the still strongly limited statistical data and the complexity of the involved processes, only order-of-magnitude estimates can be achieved. A first preliminary analysis based on quantitative information from the European Alps and Glacier Bay National Park indicates event recurrence times of about 10³ to 10⁴ years per km² of steep icy peaks with an increase of about a factor of 5 as documented for the Alps during the past few decades. Applying these results to the slopes in the catchment of three glacial lakes of high practical interest provides probabilities of ocurrence per year of 0.01 to 0.001 for Laguna Palcacocha (Cordillera Blanca, Peru), 0.1 to 0.01 for Lower Barun Lake (Nepal Himalaya) and 0.1 to 0.01 for the system of lakes which is likely to form during the coming decades at Great Aletsch glacier (Swiss Alps) where presently no lake exists.

Such first estimates indicate important possibilities for quantitative hazard and risk assessments but need further improvement by systematic data collection about large catastrophic mass flows in cold mountains and by analysing the key environmental factors in a more differentiated way.

How to cite: Haeberli, W., Allen, S., and Frey, H.: Estimating probabilities of occurrence related to impacts on glacial lakes from large rock-ice avalanches , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2511, https://doi.org/10.5194/egusphere-egu22-2511, 2022.

Catastrophic mass flows originating from the mountain cryosphere can cause widespread loss of life, destruction of property, and significant geomorphological reworking along flow paths. Based on in-situ field investigations, high-resolution satellite imagery, digital elevation models (DEMs), seismic records, and meteorological data, we present the process reconstruction, triggering mechanism, and downstream implications of a 50 Mm3 ice-rock avalanche and mass flow that originated from 6500 m asl of the Sedongpu basin in southeastern Tibet on 22 March 2021.The avalanche transformed into a highly mobile mass flow which temporarily blocked the Yarlung Tsangpo river. The avalanche flow lasted ~5 minutes and produced substantial geomorphological reworking. This event, and previous ones from the basin (a total of ~50 Mm3 on October 2017 and into 2018 occurring close to the 2021 ice-rock avalanche source region, and the detachment of the low-angle tongue of Sedongpu Glacier in two separate events with a total of ~130 Mm3 on 17/18 October and 29 October 2018), occurred concurrently with, or shortly after periods characterized by record positive air temperature anomalies, which may have contributed to instability of the mountain cryosphere. The occurrence of future large mass flows from the basin under anthropogenic warming cannot be ruled out, and their likelihood and impacts must be carefully considered given potential risks to life and implications for sustainable hydropower and associated socioeconomic development along the Brahmaputra.

How to cite: Yang, W., Zhao, C., Westoby, M., An, B., Wu, G., Wang, W., Wang, Z., Wang, Y., and Dunning, S.: Process and mechanisms on the occurrence of massive glacier-rock avalanches in the southeastern Tibetan Plateau under anthropogenic warming, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5835, https://doi.org/10.5194/egusphere-egu22-5835, 2022.

Various studies show that changes in the climate system, such as temperature rise and extreme precipitation events, strongly influence gravity driven hazards. Within the  research program "Climate Change Impacts on Alpine Mass Movements'', we develop a framework to model mass movement risk altered by climate and socio-economic drivers. In a first approach, we've modeled snow avalanche risk in Switzerland for the current climate situation and three avalanche hazard scenarios. For each of these scenarios we've considered different 3-day increases in snow height for avalanche formation, derived from meteorological stations. For the modelling we've applied the RAMMS::LSHIM Large Scale Hazard Indication Mapping algorithm combining the delineation of potential release areas from a high-resolution terrain model with a forest layer to depict the spatial distribution of avalanche impact for each of the chosen scenarios.
To model possible climate change effects on snow avalanche hazard, we use down-scaled data from the CH2018 climate change scenarios as input for the  model "SNOWPACK''. The so-derived changing avalanche hazard disposition is simulated with the RAMMS::LSHIM method and risks are analysed with the probabilistic, Python-based risk assessment platform CLIMADA using high resolution building layers to identify monetary assets and assign vulnerabilities. The results are spatio-temporally explicit risk maps, depicting changes of snow avalanche risks based on the combination of exposure and vulnerability information. These maps allow for the appraisal of appropriate risk management options and thereby contribute to decision support and highlight areas where adaptation measures to climate change might be needed.

How to cite: Ortner, G., Bründl, M., Kropf, C. M., Bühler, Y., and Bresch, D. N.: Climate change impacts on snow avalanche risk in alpine regions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8571, https://doi.org/10.5194/egusphere-egu22-8571, 2022.

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.

How to cite: Niggli, L., Allen, S., Frey, H., Huggel, C., Kassenov, M., Moldobekov, B., Petrakov, D., Raimbekova, Z., Reynolds, J., and Wang, W.: GLOF risk management experiences and options in a global context, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10026, https://doi.org/10.5194/egusphere-egu22-10026, 2022.

Glacier and permafrost hazards in cold mountain regions encompass various flood and mass movement processes that are strongly affected by climate change. Rising temperatures cause glacier retreat, permafrost thawing and degradation, with underground warming continuously propagating at greater depths. These cumulative changes, happening at different time scales, generally exacerbate slope stability and increase the probability for destructive mass movement events. Outbursts of glacial lakes, which are newly forming and growing with glacier retreat, are destructive processes with potential reaches of several hundreds of kilometers. These events often involve chains of cascading and interacting mass movement processes, threating mountain communities which are typically highly vulnerable, but also putting at risk critical infrastructure such as roads, buildings, agricultural land and hydropower installations.

Here we present a series of research and cooperation projects, funded by the Global Programme Climate Change and Environment of the Swiss Agency for Development and Cooperation (SDC). These projects supported the development of guidelines for hazard assessment, contributed substantially to the elaboration of risk management guidelines for Glacial Lake Outburst Floods (GLOFs) for India, and eventually led to supporting the design and implementation of a GLOF Early Warning System (EWS) in Sikkim, India.

From 2016 to 2017, a large consortium of international experts from the Standing Group on Glacier and Permafrost Hazards (GAPHAZ) of the International Association of Cryospheric Sciences and International Permafrost Association (IACS/IPA), elaborated a technical guidance document on the assessment of glacier and permafrost hazards in mountain regions. This guidance document reflects the current state-of-the-art of future oriented, scenario based hazard assessment and mapping, supported by physically based, numerical models. Building on that, scientists involved in the elaboration of this document have been invited as international experts in the elaboration of Guidelines for the Management of Glacial Lake Outburst Floods for India, led by the National Disaster Management Authority (NDMA) of the Indian Government. This document builds on the concepts in the GAPHAZ guidelines, but beyond hazard assessment includes also relevant aspects of risk management and DRR, while being specifically tailored to the situation of Indian Himalayan States. Currently efforts are ongoing to implement a multi-lake EWS in the Teesta River Basin in Sikkim, India with the support of NDMA. This project, which also involves the government of Sikkim, local stakeholders, Swiss universities and companies and SDC, is considered by NDMA as a pilot study for the implementation of the new GLOF management guidelines described above.

These continued long-term efforts provide invaluable learnings on collaborative scientific efforts, transdisciplinary work at the science-policy interface, and joint efforts of the academia, public and private sector towards real world applications of disaster risk management under challenging conditions.

How to cite: Frey, H., Allen, S., Huggel, C., and Kashyap Sharma, D.: Glacier and permafrost hazard and risk management: from science to policy and implementation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10234, https://doi.org/10.5194/egusphere-egu22-10234, 2022.