Displays

Despite the widespread need to use sea-level rise information in coastal adaptation decision making, the production of this information rarely starts from a decision making perspective. This constitutes a major gap, because the specific sea-level information needed for adaptation depends on the type of decision a coastal decision maker is facing. Recent work developed in the context of the World ClimateResearchProgram (WCRP) Grand Challenge “Regional Sea-Level Change and Coastal Impacts” and the Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) of the Intergovernmental Panel on Climate Change (IPCC) has started to address this gap by drawing upon the decision analysis literature. This paper presents this work identifying what kind of mean sea-level rise (SLR) information is needed for local coastal adaptation decisions. A special emphasis is placed on the contributions of the melting of the ice sheets of Greenland and Antarctica to global mean SLR, as these processes may contribute significantly to future SLR and, at the same time, are most uncertain. First, different types of coastal adaptation decisions are characterized in terms of decision horizons and users' uncertaintytolerance. Next, suitable decision analysis approaches and sea-level information required for these are identified. Finally it is discussed if and how these information needs can be met given the state-of-the-art of sea-level science. It is found that four types of information are needed: i) probabilistic predictions for short term decisions when users are uncertainty tolerant; ii) high-end and low-end SLR scenarios chosen for different levels of uncertainty tolerance; iii) upper bounds of SLR for users with a low uncertainty tolerance; and iv) learning scenarios derived from estimating what knowledge will plausibly emerge about SLR over time. Probabilistic predictions can only be attained for the near term (i.e., 2030-2050) and for locations for which modes of climate variability are well understood and the vertical land movement contribution to local sea-levels is small. Meaningful SLR upper bounds cannot be defined unambiguously from a physical perspective. Low to high-end scenarios for different levels of uncertainty tolerance, and learning scenarios can be produced, but this involves both expert and user judgments. The decision analysis procedure elaborated here can be applied to other types of climate information that are required for adaptation purposes.

How to cite: Hinkel, J.: Generating sea-level information for coastal adaptation: a risk management perspective, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4989, https://doi.org/10.5194/egusphere-egu2020-4989, 2020.

Arctic earth surface systems are undergoing unprecedented changes, with permafrost thaw as one of the most striking examples. Permafrost is critical because it controls ecosystem processes, human activities, and landscape dynamics in the north. Degradation (i.e. warming and thawing) of permafrost is related to several hazards, which may pose a serious risk to humans and the environment. Thaw of ice-rich permafrost increases ground instability, landslides, and infrastructure damages. Degrading permafrost may lead to the release of significant amounts of greenhouse gases to the atmosphere and threatens also biodiversity, geodiversity and ecosystem services. Thawing permafrost may even jeopardize human health. Consequently, a deeper understanding of the hazards and risks related to the degradation of permafrost is fundamental for science and society.

To address climate change effects on infrastructure and human activities, we (i) mapped circumpolar permafrost hazard areas and (ii) quantified critical engineering structures and population at risk by mid-century. We used observations of ground thermal regime, geospatial environmental data, and statistically-based ensemble methods to model the current and future near-surface permafrost extent at ca. 1 km resolution. Using the forecasts of ground temperatures, a consensus of three geohazard indices, and geospatial data we quantified the amount and proportion of infrastructure elements and population at risk owing to climate change. We show that ca. 70% of current infrastructure and population in the permafrost domain are in areas with high potential for thaw of near-surface permafrost by 2050. One-third of fundamental infrastructure is located in high hazard regions where the ground is susceptible to thaw-related ground instability. Owing to the observed data-related and methodological limitations we call for improvements in the circumpolar hazard mappings and infrastructure risk assessments.

To successfully manage climate change impacts and support sustainable development in the Arctic, it is critical to (i) produce high-resolution geospatial datasets of ground conditions (e.g., content of organic material and ground ice), (ii) develop further high-resolution permafrost modelling, (iii) comprehensively map permafrost degradation-related hazards, and (iv) quantify the amount and economic value of infrastructure and natural resources at risk across the circumpolar permafrost area.

How to cite: Hjort, J., Karjalainen, O., Aalto, J., Westermann, S., Romanovsky, V., Nelson, F., Etzelmüller, B., and Luoto, M.: Degrading permafrost threatens Arctic nature and built environment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8408, https://doi.org/10.5194/egusphere-egu2020-8408, 2020.

The increasing rockfall frequency in high mountain rockwalls is generally associated with global warming via the permafrost warming but long series of high resolution data on rockfall are still necessary to better appreciate the evolution of their frequencies and volumes, and to better understand their triggering factors.

Here we present an inventory of rockfalls surveyed by terrestrial laser scanning (LiDAR) since 2005 in the east face of the Tour Ronde (3792 m a.s.l.) in the Géant glacial basin (Mont Blanc massif).

Between 2005 and 2018, the rockwall was scanned 12 times, giving 11 comparisons of 3D models [1]. These highlighted a very intense morphodynamics with 91 destabilizations with volumes between 1 and 15,578 m³ for a total volume of 31,610 m³ (mean erosion rate: 29,8 mm.yr^-1). In the first year of measurement, the Bernezat spur was affected by a collapse of more than 700 m³ [2]. Then, it was affected by rockfalls not exceeding a few tens of m³. On the other hand, in the rest of the face, there is a very strong increase in rockfall activity, especially during the hot summer 2015 at the end of which (August 27) the most voluminous collapse of the whole period occurred.

The modelled surface temperature distribution at the scale of the Mont Blanc massif [3] attests to the presence of permafrost throughout the rockslope, confirmed by temperature measurements carried out at 3, 30 and 55 cm deep in the rock at the base of the Bernezat spur between October 2006 and May 2009. In addition, the main collapses left massive ice, at the level of their scar, more or less mixed with rock debris. These different elements, associated with the fact that collapses occur essentially during and following the highest summer heat, point to the role of degradation of permafrost [4]. A collapse on December 4, 2018 at the level of the small spur located at the foot of the Bernezat and whose volume is estimated at 7000 m³ reinforces this hypothesis since the detachment surface was covered - except for its margins - by massive ice. This has been sampled and its dating will perhaps confirm the age of the ice present in the cracks of the permafrost-affected rockwalls of the Mont Blanc massif. In 2017, a collapse of 44,000 m³ in the north face of the Aiguille du Midi (3842 m a.s.l.) had exposed 4060 calBP ice. In the Tour Ronde case, ice/snow cover changes and glacial debutressing could also partly explain the rockfall activity.

[1] Ravanel L. et al. (2010). Revue Française de Photogrammétrie et de Télédétection, 192 : 58-65.

[2] Rabatel A. et al. (2008). Geophysical Research Letters, 35: L10502.

[3] Magnin F. et al. (2015). Geomorphologie, 21: 145-162.

[4] Ravanel L. et al. (2017). Science of the Total Environment, 609: 132-143.

How to cite: Lhosmot, A., Ravanel, L., Preunkert, S., Magnin, F., Guillet, G., Rabatel, A., and Deline, P.: 14 years of LiDAR monitoring and insights into ice of rockwall permafrost: the east face of the Tour Ronde (3792 m, Mont Blanc massif), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11374, https://doi.org/10.5194/egusphere-egu2020-11374, 2020.

Ice-driven mechanical weathering in mountainous environment is considered an efficient process for slow preconditioning of rockfalls. In this study (Musso Piantelli et al., 2020), we simulate with an innovative experimental approach subcritical fracture-propagation under frost-wedging conditions through pre-existing weaknesses of intact rock bridges. Two series of freeze-thaw experiments in an environmental chamber have been designed to investigate and monitor the propagation of artificially-induced fractures (AIF) in two twin gneiss samples. By employing 3D X-Ray Computed Tomography and a displacement sensor, an accurate characterization and new insights into the fracture-propagation mechanism are provided. Our results demonstrate that frost wedging propagated the AIFs of 1.25 cm2 and 3.5 cm2 after 42 and 87 freeze-thaw cycles, respectively. The experiments show that volumetric expansion of water upon freezing, cooperating with volumetric thermal expansion and contraction of the rock, plays a key role in fracture widening and propagation. Based on these results, this study proposes that: (i) frost wedging exploits intrinsic pre-existing weaknesses of the rock; (ii) the fracturing process is not continuous but alternates propagation stages to phases of tensile stress accumulation; and (iii) downward migration of “wedging grains”, stuck between the walls of the fracture, increases the tensile stress at the tip, widening and propagating the fractures with each freeze-thaw cycle. The experimental design developed in this study offers the chance to visualize fracture-propagation in natural joints quantifying the long-term efficiency of this process in near-natural scenarios.

REFERENCES

Musso Piantelli, F., Herwegh, M., Anselmetti, F.S., Waldvogel, M., Gruner, U., (2020). Microfracture propagation in gneiss through frost wedging: insights from an experimental study. Natural Hazards, 1-18. https://doi.org/10.1007/s11069-019-03846-3

How to cite: Anselmetti, F., Musso Piantelli, F., Herwegh, M., Waldvogel, M., and Gruner, U.: Experimental microfracture propagation in gneiss through frost wedging, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8236, https://doi.org/10.5194/egusphere-egu2020-8236, 2020.

Instabilities occurring on temperate glaciers in the Alps have been the subject of several studies, which have highlighted preliminary conditions and possible precursory signs of break-off events.

Since 2013, the Planpincieux Glacier, located on the Italian side of Mont Blanc massif (Aosta Valley), has been studied to analyse the dynamics of ice collapses in a temperate glacier.

These analyses have been conducted for several years, enabling the assessment of surface kinematics on the lower glacier portion and the different instability processes at the glacier terminus. During the period of the study, especially in the summer seasons, increases in velocities of the whole right side of the glacier tongue have been recorded. This fast sliding movement is mainly induced by water flow at the bottom of the glacier.

In 2019 summer season, the increase of speed coincided with the opening of a large crevasse, which outlined a fast moving ice volume, assessed by photogrammetric techniques as 250.000 m³.

According to the risk scenarios, the collapse of this ice volume from the glacial body would have reached the valley floor, potentially affecting the access road to the Val Ferret valley.

Considering the potential risk, a civil protection plan has been deployed by the monitoring team of the Aosta Valley Autonomous Region, Fondazione Montagna sicura and CNR-IRPI.

Glacier displacements, variations in the glacier morphology and environmental variables, such as air temperature, rain and snowfall, have all been taken into account to implement the monitoring plan.

This work outlines and summarises the steps used to develop the scientific knowledge into an integrated monitoring plan and a closure plan for the Val Ferret valley.

How to cite: Perret, P., Troilo, F., Gottardelli, S., Mondardini, L., Dematteis, N., Giordan, D., and Segor, V.: Ice avalanche risk management from the Planpincieux glacier (Courmayeur - Italy), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9717, https://doi.org/10.5194/egusphere-egu2020-9717, 2020.

In recent years, the number and size of glacial lakes in mountain regions have increased worldwide associated to the climate-induced glacier retreat and thinning. Glacial lakes can cause glacial lake outburst floods (GLOFs) which can pose a significant natural hazard in mountainous areas and can cause loss of human life as well as damage to infrastructure and property.

The glacial landscape of the Jostedalsbreen ice cap in south-western Norway is currently undergoing significant changes reflected by progressing glacier length changes of the outlet glaciers and the formation of new glacial lakes within the recently exposed glacier forefields. We present a new glacier area outline for the entire Jostedalsbreen ice cap and the first detailed inventory of glacial lakes which were formed within the newly exposed ice-free area at the Jostedalsbreen ice cap. In detail, we explore (i) the glacial lake characteristics and types and (ii) analyse their spatial distribution and hazard potential.

For the period from 1952-1985 to 2017/2018 the entire glacier area of the Jostdalsbreen ice cap experienced a loss of 79 km². A glacier area reduction of 10 km² occurred since 1999-2006. Two percent of the recently exposed surface area (since 1952-1985) is currently covered with newly developed glacial lakes corresponding to a total number of 57 lakes. In addition, eleven lakes that already existed have enlarged in size. Four types of glacial lakes are identified including bedrock-dammed, bedrock- and moraine-dammed, moraine-dammed and ice-dammed lakes. Especially ice- or moraine-dammed glacial lakes can be the source of potentially catastrophic glacier lake outburst floods. According to the inventory of glacier-related hazardous events in Norway GLOFs represent the most common hazardous events besides ice avalanches and incidents related to glacier length changes. Around the Jostedalsbreen ice cap several historical but also recent events are documented. The majority of the events caused partly severe damage to farmland and infrastructure but fortunately no people have been harmed by today.

Due to the predicted increase in summer temperatures for western Norway until the end of this century, it is very likely that the current trend of an accelerated mass loss of Norwegian glaciers will continue. As one consequence of this development, further new lakes will emerge within the newly exposed terrain. The development of new glacial lakes has diverse regional and global socio-economic implications. Especially in mainland Norway, where glaciers and glacier-fed streams have a high importance for hydropower production, tourism and climate research it is essential to gain a better understanding of the possible impacts of glacial lakes for being prepared for risks but also advantages arising from these newly emerging landscape elements.

How to cite: Laute, K. and Beylich, A. A.: The formation of new glacial lakes at the Jostedalsbreen ice cap in southwest Norway and their future implications, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5012, https://doi.org/10.5194/egusphere-egu2020-5012, 2020.

Anticipating the formation of lakes in deglaciating mountains represents an important step towards the identification of both, new possible water storage options and potential hazards. This is particularly crucial in the Peruvian Andes which are characterized by strong precipitation seasonality. Dwindling glacier contribution to river streamflow, particularly during the dry season (May-September), combined with increasing water demand suggest considerable levels of potential future water scarcity in some regions. Within the near future, the water use potential of new lakes needs to be further explored for main sectors of water use. At the same time, emerging risks must be considered for downstream populations (i.e. lakes increasingly exposed to landslides, avalanches, rock falls or ice detachments).

In this context, the presented future lakes inventory aims to provide information for long-term planning and comprehensive territorial management. The methodology is based on numerical ice thickness distribution (±30% uncertainty range) and bedrock modelling with the GlabTop (Glacier bed Topography) model. This tool in combination with a visual inspection protocol based on geomorphological criteria allows for reasonable estimates and evaluation of potential future lakes differentiated by confidence levels. The three applied morphological criteria were: i) downslope (priority) and upslope increase of surface slope, ii) lateral glacier narrowing, and iii) heavily crevassed areas following a crevasse-free zone. The results are most robust for the identification of potential formation sites rather than the precise area, depth or volume of potential lakes. Thus, the inventory needs to be understood as a first order of magnitude.

A total of 287 sites of potential future lakes (>1ha) have been identified which would be distributed within 11 out of 18 still glacier-covered mountain ranges in Peru. The total lake volume would be about 231 millions of m³ which corresponds to around 0.5-1.0% of the entire estimated national glacier volume (~38 km³). While on a country scale this might not be much, locally the projected water storage could play an important role. Actually, a major number (175) of the identified lakes has already developed or is likely to form within a few decades. This underlines the need for more research and integrated territorial management within a timely manner.

The current methodology and compiled inventory provide an important tool for prospective and integrated risk, water and land management within a context of hydroclimatic and socioeconomic impacts in the Andes of Peru and elsewhere. Follow-up studies should use new data and additional methods including in-situ techniques to corroborate and update results within a rapidly changing Andean environment. Additionally, a realistic and detailed evaluation should be particularly conducted for possible lakes of higher priority concerning water supply and outburst flood susceptibility.

How to cite: Guardamino, L., Drenkhan, F., Haeberli, W., Muñoz, R., and Cochachin, A.: A national inventory of potential future lakes in the deglaciating cordilleras of Peru for integrative water and risk management, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12399, https://doi.org/10.5194/egusphere-egu2020-12399, 2020.

Mountain glacier is an indispensable supplier and modulator of freshwater to human’s sustenance in extensive cold and arid areas of the world. Melt waters from glaciers are widely used for ecosystem integrity, agricultural irrigation, hydropower operation, domestic and industrial activities. Under the background of global environmental changes such as global warming and regional population growth, linking climate-related glacio-hydrological changes to regional population growth is of the essence. However, a global assessment on opportunities/risks caused by glacial meltwater changes and population growth has not been presented until now. In this study, the population changes in glacier-fed area (GFA) for historical (1980-2015) and future (2010-2100) periods at the global, continental, national and basin scales were first mapped. Then, the opportunities/risks associated with population growth and glacier meltwater changes during 1980-2100 in 42 large-scale glacierized drainage basins with a minimum population of 10 thousand in 2015 were analyzed. Results reveal that the population living in the world’s GFA was 2030 million in 2015 and it was rapidly increased from 1278 million in 1980. The total population in GFA would continue to increase until a maximum is reached (e.g. peak population will appear around 2060 under the intermediate pathway for mitigation and adaptation, i.e. SSP₂), beyond which the population would gradually decline. The opportunities/risks vary across basins and decades. Both of them are greatest in the Indus River basin, where the increase in glacial meltwater can seasonally satisfy the basic needs of additional 87 million people from the 2000s to 2040s, but about 200 million would be exposed to severe water scarcity due to the decrease in glacial meltwater and the population increase after the 2040s. 

How to cite: Su, B., Xiao, C., and Chen, D.: Opportunities & risks associated with global glacial meltwater changes and regional population growth from 1980 to 2100, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3853, https://doi.org/10.5194/egusphere-egu2020-3853, 2020.

The catastrophic detachment of Kolka Glacier in Russia was long thought to be a unique occurrence (e.g., Haeberli et al., 2004), but recent events in Tibet, Alaska, Argentina and China have increased the urgency to understand these processes and the risk they pose to mountain communities and infrastructure. Most notably, the tongues of two neighboring glaciers in Tibet detached only a few weeks apart in 2016, the first killing nine herders and hundreds of their livestock. In 2013 and 2015 Flat Creek Glacier in Alaska’s Saint Elias Mountains lost half of its total area in two large detachments. The resulting destructive mass flows left a clear scar in the landscape, piling debris up to 30 m thick and spreading it over 8 km². Recent investigations by Kääb et al. (2018), Gilbert et al. (2018) and Jacquemart et al. (in review) suggest that the failures in Tibet and Alaska share three main drivers: temperate ice restricted by a frozen glacier tongue, a clay-rich bed, and increased meltwater input to the base of the glacier, driven by increasing summer temperatures.

Here we ask whether these glacier detachments are indeed a new, emerging hazard or whether we simply have not previously recognized the signs they leave in the landscape. Only a long-term record of observations stretching beyond the modern satellite era, can reliably answer the question about possibly increasing frequencies. In order to start building some understanding of the nature of such deposits, we investigated the internal structure and landscape setting of the 2013 and 2015 detachment deposits at Flat Creek. We performed electrical resistivity tomography surveys to estimate their ice content and ice distribution. In addition we analyzed grain size distributions and orientations in the deposits to see if they can be clearly distinguished from other glacio-fluvial deposits. To understand if glacier detachments have happened in this region before, we performed the same analysis on large debris deposits found downstream of a neighboring glacier. We combine this field evidence with remote sensing analysis of the temporal evolution of the glaciers and detachment deposits in Alaska, Tibet and Russia to understand the signatures of these catastrophic events in the landscape. Our preliminary results for Alaska show that the glacier itself is a bad indicator of past events, as the ice response quickly masks the detachment. Additionally, we found ice in the deposits to be highly broken up and ground, though never the less able to endure multiple years. Unlike a traditional debris-flow deposits, the glacier-detachment deposits exhibit a lack of grain-size sorting, and the grain orientations appear highly chaotic, with a tendency toward vertical orientations. As such, the deposits appear clearly distinct from the surrounding hillslope, and further analysis will show to what extent they can be distinguished from other glacio-fluvial deposits.

How to cite: Jacquemart, M., Leopold, M., Welty, E., Lajoie, L., Loso, M., and Tiampo, K.: Geomorphic signatures of large-scale glacier detachments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4110, https://doi.org/10.5194/egusphere-egu2020-4110, 2020.

Climate change generates significant impacts on high mountain regions, especially considering the sensitivity of tropical glaciers. However, information about rock glaciers are very scarce and there is very limited research in this field in Peru. Rock glacier concentrate mainly in the southern part of Peru where 95% of rock glaciers are located. Here we present for the first time an overview of rock glacier occurrence and characteristics in Peru.

The Cordilleras Huanzo and Chila are located in the mountain ranges in the southern region of Peru, Huanzo in the administrative region of Apurimac, Arequipa, Cusco and Ayacucho, while Chila in Arequipa. Both cordilleras extend from S 15°39'41.36" to 14°03'17.54" and W 73°24'12.55" to 71°27'113.20". For this study, remote sensing tools and geographic information system were applied, using images from Google Earth-Pro and SASPlanet, corrected DEM ALOS Palsar (12.5m), MERIT DEM (90m) and WorldClim data (1970-2000) 1 km².

The results indicate that in the cordillera Huanzo there are 317 rock glaciers with a total area of 26.97 km² and in the cordillera Chila there are 289 rock glaciers with 17.96 km². Concerning their activity or dynamic there are 295 intact (active and inactive) rock glaciers and 311 relict or fossil rock glaciers.

The results further indicate that rock glaciers are located in thermal ranges between -1.53°C and 3.97°C. The relict or fossil types are located in the thermal range between -1.34°C and 3.97°C, while intact types between -1.53°C and 2.56°C. The rock glaciers of the cordillera Huanzo are located at an average altitude of 4497 to 5221 m.a.s.l., while in the cordillera Chila at 4470 to 5454 m.a.s.l. The aspect is predominantly S to SW.

Rock glaciers contain ice which may represent a potential water reserve in arid regions in Southern of Peru. The greatest distribution of these resources is found in the Camana and Ocoña basins of the Pacific watershed with 38.1 km² of rock glacier area. In the Atlantic watershed, 6.8 km² of rock glaciers are located in the Alto Apurimac and Ocoña basins.

How to cite: Medina, K., Loarte, E., Badillo, E., Leon, H., Castillo, F., and Huggel, C.: Distribution and morpho-thermal characteristics of rock glaciers in southern Peru: case, Cordilleras Huanzo and Chila, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4442, https://doi.org/10.5194/egusphere-egu2020-4442, 2020.

One of the effects of climate change on tropical glaciers is the accelerated reduction of their glacial tongue, reflected in a morphometric variation. Many glaciers that had pronounced tongues and that extended through a valley (Valley glacier) now have reduced their fronts located in the upper parts of the valleys (Mountain glacier).

This has been studied with glaciers of Peru located in 18 mountain ranges located from S 8°20'56" to 15°53'26" and W 77°56'10" to 69°05'14", which are an important solid water reserve that directly supplies the population of 11 departments.

The study focused on the "digit 1" (primary classification) of the Global Land Ice Measurement from Space (GLIMS), which classifies the glaciers mainly in: valley glaciers and mountain glaciers. The processing of raster and vector data through the use of geographic information system and remote sensing tools allowed to analyze the changes and variations affecting glaciers with respect to their morphometry. For this, a comparison was made between glacier coverage in 2016 (using images Sentinel 2), produced by INAIGEM, and the baseline of the glacier coverage of 1955 and 1970 (using aerial photography), from the first inventory of glaciers in Peru, produced by Hidrandina S.A.

The results show a significant morphometric variation of 83.7%, where valley glaciers (from Hidrandina inventory) became mainly mountain glaciers. Nowadays only four mountain ranges have mountain glaciers inside whereas in the past it were nine. When we analyze the results for watersheds, the most morphometric changes were 89% in the Atlantic watershed, followed by 57% in the Pacific watershed; in the Amazon watershed there was not any registration of any mountain glaciers since the first inventory in Peru. The surface changes do not show specific any predominant aspect, and average slopes are between 25° and 50°.

The glacial tongues that are considered valley glacier area located in ablation zones, where the mass balance is negative and there is more susceptibility to reducing their mass and, consequently, to variations in shape and size in a short period. This change has been accentuated in recent decades.

How to cite: Loarte, E., Medina, K., Curo, Y., Leon, H., Quiñonez, F., Castillo, F., and Huggel, C.: Variation of glacial dynamics in Peru: from valley glaciers to mountain glaciers in a context of climate change, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4452, https://doi.org/10.5194/egusphere-egu2020-4452, 2020.

With the climate warming, high mountainous areas, including cryosphere, show more frequent and early outbreaks trend in flood hazard, cursing more losses to downstream areas. Based on meteorological, hydrological and MODIS snow cover data, using the snowmelt runoff model (SRM) to simulate and verify the spring runoff result during the snowmelt period from 1990 to 2012 in the upper Heihe River. SRM model simulates results shows it has a high accuracy (NSE = 0.7229), which can be used to predict the future flood intensity changes in studying area. In order to predict the trends of Heihe River Basin in flood return periods under the different future climate change scenarios, analyze used the temperature and precipitation forecast data. By the end of this century, the result of flood runoff shows differently according to climate change scenarios compared with the basic period. In RCP 2.6, due to the small changes of the temperature and precipitation, flood intensity will change slightly around 10% in all return periods; in RCP 4.5, it will increase about 20%; in RCP 8.5, return periods may be rise over 30%.

How to cite: Zhu, G.: Spring Snowmelt Flood Estimate in the Upper Heihe River under Climate Change Scenarios, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4604, https://doi.org/10.5194/egusphere-egu2020-4604, 2020.

Miage Glacier Lake is a glacial marginal lake that forms on the right snout of Miage Glacier, located in the Val Veny Valley (Aosta Valley – Italy). The lake has been experiencing seasonal drainages at least since the 1930’s and 15 events have been documented from 1930 to 1990. The lake position has been almost unvaried since the first existing maps of late 1700, but lake morphology experienced major changes after the drainage event of September 2004, after which the water level could not reach again a sufficient height to fill the 3 depressions that used to form a bigger lake until 2003 (36.000 m²). The lake having decreased its volume and surface, it did not seem by that time that GLOF from Miage Lake could cause any risk downstream (Deline et Al. 2004), but recent observation of Sentinel 2B satellite images  led to the individuation of unusual lake expansion towards its north shore. Thus, an UAV survey was performed to assess the actual lake area in July 2019, and the integration of satellite images and UAV surveys demonstrated a consistent lake area expansion since 2015. Moreover an emptying occurred in late August 2019 so that another UAV survey could be performed, and water volume estimation could be performed by means of DEM differencing. An important water volume was individuated, reaching 196.000 m³ and an estimation of maximum subglacial GLOF debit has been performed. Global evolution trend of the glacier mass has been evaluated by analyzing different airborne Lidar surveys (1991-2008). A cumulated geodetic mass balance could be thus inferred and found good matching with remote sensed analysis (2003-2012) performed by means of stereo satellite imagery by Berthier et Al. in 2014. Average surface lowering of the glacier surface could be analyzed and average values of -1.12 m/yr could be observed around lake Miage. The strong elevation loss of Miage Glacier lower snout is probably the cause of the lowering of the piezometric level in intra-glacial water limiting maximum altitude that water level can reach in the lake, so that the bigger basin of 2004 cannot be filled anymore. Moreover, an analysis of recent GLOFs of Miage Lake gave an insight about the possible dynamics of lake subglacial drainage, suggesting the existence of 2 different mechanisms of emptying as some events occur with lower water debits, earlier in the season, and other events occur later in the summer season with major water debits. Similar GLOF behavior has been described at Plaine Morte Glacier Lake in the Canton of Bern-Switzerland (Fahrni 2018). Field surveys of 2018 showed very likely evidence of hydrostatic uplift of the ice dam, so multi temporal UAV surveys and GNSS field surveys are planned for 2020 to possibly highlight evidences of hydrostatic uplift of the glacier prior to GLOFs.

How to cite: Troilo, F., Segor, V., Perret, P., Bertholin, M., Mondardini, L., and Gottardelli, S.: Analysis of the Miage Glacier Lake GLOFs (Aosta Valley - Italy)., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5454, https://doi.org/10.5194/egusphere-egu2020-5454, 2020.

Climate change has serious implications for the cryosphere and a close relationship between the instability of rock faces and the changes in high mountain permafrost is suspected. Although, the number of rockfall events in Alpine areas is increasing, detailed analyses of the frequency and runout distances in high altitudes are rare. This study gives an insight into the rockfall activity in the Ötztal Alps in Tyrol, Austria. A systematic observation utilizing bi-temporal ALS-DTMs in combination with orthoimages revealed a total of 93 rockfalls over an area of 637 km² in the period from 2006 to 2010. Since more than 90 % of the rockfall release areas were mapped in potential permafrost areas, a correlation between rockfall activity and climatically driven degradation of permafrost in bedrock is very likely. 18 rockfall events, ranging in volume from 69 to 8420 m³, were suitable for runout assessments. To estimate the maximum range of future rockfalls with empirical models, values of 30 ° (Fahrböschung) and 26 ° (minimum shadow angle) can be proposed for risk assessment at a regional scale (1:25,000 – 1:100,000). Rockfalls occurring on snow or ice may also go below these values.

Keywords: Rockfall, Permafrost, digital elevation model; runout distance, Fahrböschung, minimum shadow angle, Ötztal Alps

How to cite: Knoflach, B., Tussetschläger, H., Sailer, R., Meißl, G., and Stötter, J.: A Rockfall inventory: Ötztal Alps, Tyrol, Austria, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5945, https://doi.org/10.5194/egusphere-egu2020-5945, 2020.

Glacier mass loss and consequent termini retreat lead to formation and growth of glacier lakes. In the Mt. Elbrus region, outbursts of lakes formed in recent decades have led to human casualties and significant damage. Building codes of Russian Federation on engineering surveys do not regulate the possibility of glacier lake formation in front of retreating glaciers, which can lead to errors in the future engineering design. Using ground based and airborne GPR data, as well as global ice thickness models, we have identified areas of potential lake formation on glacier bed for a number of glaciers in the Mt. Elbrus region. The method was tested by retrospective modeling for Bolshoy Azau and Djikiugankez glaciers bed topography on the base of 1957 topographic map. In the areas where glaciers disappeared by 2017, out of 13 simulated closed bed depressions 7 existing lakes were predicted by the hydraulic potential. 6 closed depressions on Djikiugankez glacier bed as of 1957 are currently absent, which might be related to the model uncertainties and the original DEMs errors, as well as to possible filling of lakes by sediments. Retrospective modeling of the Bashkara glacier bed topography based on SRTM DEM (2000) showed significant growth potential of the lake Lapa. Retrospective modeling of the Kaayarty glacier bed topography has not provided a clear answer about the possibility if subglacial lake outburst flood was a trigger for catastrophic debris flow formation during the summer of 2000.

In case of total disappearance of Bolshoy Azau, Djikiugankez and Bashkara glaciers at least 11 new lakes with total area of about 1.7 km² and an average depth of 8 m will form. While the deepest lake will appear in ablation zone of Bolshoy Azau glacier (at elevation 3100-3400 m a.s.l.) the largest in area (1 km²) glacial lake will be formed at the Djikiugankez snout with maximum depth of 40 m and mean depth of 7.2 m. The simulation also showed that in the present conditions, glacier bed lakes of different number and size may also exist under studied glaciers. Our estimates may contain uncertainties due to low resolution of airborne GPR data and the lack of GPR data for Kaayarty glacier, DEM and ice thickness model errors. Detailed ground-based radar survey planned for the summer 2020 will enable the assessment of the size and volume of the potential lakes under Bolshoy Azau glacier.

This work was funded by RFBR grant No. 18-05-00520.

How to cite: Lavrentiev, I., Petrakov, D., Kutuzov, S., and Smirnov, A.: Assessment of glacier lakes development in Central Caucasus, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6471, https://doi.org/10.5194/egusphere-egu2020-6471, 2020.

Peruvian Cordillera Negra (8°40’ – 10°30’ S; 77°20’ – 78°30’ W) is characterised by dry semi-arid climate and a general lack of water, especially during the dry season (April – October). Numerous glacial lakes – remnants of the past glaciation of this currently glacier ice-free mountain range – thus represent an important water reservoirs. Glacial lakes sustain environmental flows during dry season, store water for grazing animals as well as simple agricultural irrigation. At the same time, climate change and socio-economic development drive increasing pressure on water resources in the region.

To further enhance potential of glacial lakes in water management, hundreds of glacial lakes of the Cordillera Negra have been equiped by damming structures in order to: (i) increase the volume of retained water; (ii) manage the outflow throughout the seasons of the year. Two general types of dams are distinguished: (i) traditional dams (built by local communities from stones, turf and clay); and (ii) modern dams (concrete or embankment earth- or rock-filled). While these dams help to retain water and the idea is promising, the implementation and dam management lag behind.

During the field visit conducted in 2019, many of the visited dams (both traditional and modern) were documented to leak through; attempts to retain as much water as possible also led to the intentional blocking of spillways, reducing dam freeboard to only tens of cm in some cases. In the worst case, these unacceptable management practices might result in dam overtopping or dam failure. Despite the uppermost part of the Cordillera Negra is not densely settled, some of the glacial lakes are located upstream mining areas, so that there is a risk of environmental pollution and contamination in case of flood. These observations suggest that glacial lakes can successfully be used in water mangement, however, they need to be managed properly and continuously.

How to cite: Emmer, A.: Enhancing water management by using glacial lakes: examples of opportunities and risks from deglaciated Cordillera Negra, Peru, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8631, https://doi.org/10.5194/egusphere-egu2020-8631, 2020.

Understanding permafrost development and its effect on groundwater flow patterns and fluxes in the event of future ice-age conditions is important for the long-term safety of spent nuclear fuel repositories. To assess the evolution of permafrost thickness, talik development, and groundwater flow and salinity changes at Olkiluoto, Finland, during the next 100,000 years, we solve Darcy flow coupled to heat and solute transport in three dimensions in a rectangular block representing an area of 8.8 km by 6.8 km, and down to a depth of 10 km. The set of equations is based on continuum thermo-mechanic principles. Important and highly non-linear coupling processes such as the exponential decrease of permeability with ice content in soils and rocks, solute rejection during freezing, and variable-density Darcy flow are fully taken into account. Model equations are solved using the finite element method implemented in the open source software Elmer.  High-resolution data of rock and soil permeability, thermal and physical properties, are mapped onto a 30-meter resolution grid resulting in a system of about 5 million nodes and 5 million elements. Soil layers at the surface are vertically resolved down to 0.1 meter. High contrast in permeability over short distances (from soil to granitic bedrock) make the system of equations challenging to solve numerically. Simulations are driven by RCP 4.5 climate scenario that predicts cold periods between AD 47,000 and AD 110,000. Surface boundary condition for temperature is calculated based on freezing and thawing n-factors that depend on monthly temperatures and the topographic wetness index that defines different zones of vegetation and ground cover. The thickness evolution of the six upper soil layers, including peat, above the granitic bedrock is also taken into account. Preliminary simulations are able to represent permafrost development at a high spatial resolution with evidence of important feedbacks due to permeable soil layers and faults in the bedrock that focus groundwater flow and solute transport.

How to cite: Cohen, D., Zwinger, T., Koskinen, L., and Karvonen, T.: Long-term coupled permafrost-groundwater interactions at Olkiluoto, Finland, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8972, https://doi.org/10.5194/egusphere-egu2020-8972, 2020.

One consequence of current and likely future melting of high mountain glaciers is the development of glacial lakes. Their evolution over time has implications for future water supplies in arid mountains and for the timing and magnitude of glacier hazards, such as Glacial Lake Outburst Floods (GLOFs).

GLOF initiation depends on how lakes are connected to the glacial system, resulting from myriad processes such as the destabilisation of moraine dams and glacier front calving. To better understand these processes, we have undertaken an inventory of all glacier lakes in the Cordillera Blanca of Peru for 2019. We used manual digitisation from Landsat RGB at 30m resolution and have recorded the type of lake dam and its connection with surrounding glaciers and mountain slopes. We have also obtained lake inventories from INIAGEM (Instituto Nacional de Investigación en Glaciares y Ecosistemas de Montaña; 2016) and ANA (Autoridad Nacional del Agua; 2018), and have created an automatic inventory using the Normalised Difference Water Index and Normalised Difference Snow Index in Google Earth Engine. In this presentation we compare these different inventories and discuss both the methods and effectiveness of each for understanding GLOF hazards in the Peruvian Andes. 

How to cite: Wood, J., Harrison, S., Wilson, R., Yarleque, C., Bennett, G., Caballero, A., Castromonte, J., Emmer, A., Garay, D., Garrido, H., Glasser, N., Jara, W. H., Reynolds, J., Shannon, S., Smith, R. C., Soto, E. G., Tinoco, T., Torres, J. C., Turop, E., and Vilca, O. and the Project GLOP: Mapping glacier lakes in Peru, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9741, https://doi.org/10.5194/egusphere-egu2020-9741, 2020.

The formation of new lakes in areas uncovered by retreating glaciers is a phenomenon that is often accompanying glacier retreat. On the one hand, such glacial lakes constitute a potential source of hazards and risks in the form of glacial lake outburst floods (GLOFs), but also amplify the potential reach of other mass movements when involved in cascading process chains. On the other hand, these new lakes might provide opportunities as well, as they are attractive elements in changing mountain landscapes and provide a significant water storage and hydropower potential. Here, we present an approach to establish the first global assessment of the characteristics, risks and opportunities provided by the formation of new lakes in glacierized mountain regions. This study is currently in the phase of concept development, in our contribution we present the planned methodological steps and some preliminary results.

In our approach, we draw on recently published datasets of ice thickness distributions of all glaciers around the world to detect the sites of potential future lake formation and extract general characteristics, such as lake depth and volume, as well as the elevation distribution. In combination with a new global glacial lake inventory, we estimate the total number of glacial lakes for each of the world’s mountain ranges, and contrast the share of already existing glacial lakes with the share of potential future glacial lakes. In combination with a global glacier evolution model (GloGEM), formation dates of these future lakes are estimated, considering different RCPs.

A major focus will be put on the assessment of regional hazards and risks. By analyzing the topographic potential around all future lakes from digital elevation information and a globally complete glacier inventory (RGI), the susceptibility for mass movement impacts is assessed in a generic way for each lake. Simple flow routing modeling will be used to evaluate the potential downstream impact. In combination with census data and other socio-economic indicators, a preliminary danger or risk assessment can be made in order to identify future hotspots of GLOF risks. In combination with globally available data on glacier runoff contributions to streamflow, regions are identified where more detailed evaluations of the water storage potential provided by such new lakes are of particular relevance.

The results of this work will allow anticipating hotspots of potential future GLOF hazards and risks at a local to global level. Further, important information to decision makers will be provided for long term planning regarding risk and water resources management as well as climate change adaptation measures and taking advantage of the opportunities provided by the formation of new glacial lakes.

How to cite: Frey, H., Huggel, C., Allen, S., Emmer, A., Shugar, D., Farinotti, D., Huss, M., and Machguth, H.: Towards a global assessment of future glacial lakes and related hazards, risks and opportunities, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17330, https://doi.org/10.5194/egusphere-egu2020-17330, 2020.

Despite being a rather rare phenomenon when compared to the occurrence rates of other alpine hazards (e.g. landslides, avalanches), glacial lake outburst floods (GLOFs) pose a significant threat to downvalley communities in glaciated mountain areas. Characteristically high peak discharge rates and flood volumes, documented to have reached 30,000 m³/s and > 50 million m³ in the past century, not only provide GLOFs with a landscape-forming potential but also killed a reported global total of > 12,000 people and caused severe damage to infrastructures. Extensive glacial covers and steep topographic gradients, coupled with rapidly changing socio-economical implications, make the Hindu-Kush-Himalaya (HKH) a high priority region for GLOF research, even though recent studies suggest an annual occurrence rate of 1.3 GLOFs per year across this range during the past three decades. So far, GLOF research in the greater HKH region has been predominantly focused on the classification of potentially dangerous glacial lakes derived from analysing a limited number of glacial lakes and even fewer reportedly GLOF-generating glacial lakes. Moreover, subjectively set thresholds are commonly used to produce GLOF hazard classification matrices. Contrastingly, our study is aimed at an unbiased, statistical robust and reproducible assessment of GLOF susceptibility. It is based on the currently most complete inventory of GLOFs in the HKH since the 1980’s, which comprises 38 events. In order to identify key predictors for GLOF susceptibility, a total of 104 potential predictors are tested in logistic regression models. These parameters cover four predictor categories, which describe each glacial lake’s a) topography, b) catchment glaciers, c) geology and seismicity in its surroundings, and c) local climatic variables. Both classical binary logistic regression as well as hierarchical logistic regression approaches are implemented in order to assess which factors drive susceptibility of HKH glacial lakes to sudden outbursts and whether these are regionally distinct.

How to cite: Fischer, M., Veh, G., Korup, O., and Walz, A.: Identifying key predictors for the susceptibility of Himalayan glacial lakes to sudden outburst floods, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17689, https://doi.org/10.5194/egusphere-egu2020-17689, 2020.

Rock mechanics and its numerical representation alone are challenging tasks – if you add ice to that equation, it becomes an even more complex thing to do. Nevertheless, aiming for a better understanding of rock slopes in permafrost conditions and their mechanical behaviour depending on the scale and mechanisms of interest, integrating rock and joint characteristics, also including ice can become relevant. Krautblatter et al. (2013) suggests a rock-ice mechanical model, that describes the dominating effects for the stability of high-alpine rock slopes in permafrost conditions. This study aims to select ice filled rock joints as one of the relevant effects of Krautblatter et al. (2013) and combines it with findings of the laboratory test and derived temperature dependent failure criteria of Mamot et al. (2018). We present data and strategies for implementing temperature-dependent failure criteria for ice-filled rock interfaces into numerical distinct element code and their calibration by a comparison with preceding laboratory tests. Additionally, methods for temperature transfer within the model are suggested as well as for integrating stress-dependent application of different failure criteria in the numerical formulation. Here we show a benchmark joint-constitutive-model for rock-ice mechanical systems and its implementation in a comprehensive distinct element code.

How to cite: Pläsken, R., Julian, G., Michael, K., and Philipp, M.: Stress- and temperature dependent application of joint-constitutive-models for rock-ice mechanical systems and its implementation in a comprehensive distinct element code, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18754, https://doi.org/10.5194/egusphere-egu2020-18754, 2020.

In the last decades, climate change effects are spreading on cryosphere of mid latitude high mountains, affecting all environmental and territorial components. The Italian Alpine Club (CAI) is a privileged institution for observing climate change effects on cryosphere in high mountains, as well as for supporting scientists to proper assessment studies of related natural hazards, exposure, vulnerability effects, particularly those around alpine refuges and access routes. CAI has started a cooperative research with University of Torino (UniTO), Politecnico of Milano (PoliMI) and IMAGEO srl, focused in deglaciation, permafrost degradation and slope instabilities at the Punta Gnifetti peak (“Signal Kuppe, 4554 m a.s.l.), Monte Rosa (Pennine Alps, border between Italy and Switzerland). Here is the Margherita Hut, the highest refuge in Europe and a physical-meteorological observatory, as well as home to medical and scientific UniTO laboratories.

Activities started on May 2019 with a retrospective collection and interpretation of photos and archival news on the Punta Gnifetti environment. Multi-temporal geomorphological settings are compared to meteorological historical series for creating a morphoclimatic "timeline".

Instrumental monitoring and in situ field work began on August 2019, including: 1) determination of the ice thickness of the glacial cover by using georadar; 2) characterization of the geomechanical structure of the rock mass by means of terrestrial laser scanner; 3) establishment of a topographical reference point and georeferencing of all measuring points; 4) collection of litho-structural and geomorphological data for a reference geological model of the Punta Gnifetti; 5) photogrammetric helicopter flight for the 3D reconstruction of the site; 6) direct measurements of internal areas in order to obtain as-built building plans; 7) assessment of building services.

Preliminary results are presented here, together with directions for an effective data collection to be continued on 2020, including comparative analyses designated to: a) identify the relevant geomechanical features for rock mass stability; b) verify presence of ice inside fractures; c) reconstruct the ice-covered morphology of the Punta Gnifetti peak.

How to cite: Giardino, M., Montani, A., Tamburini, A., Calvetti, F., Borghi, A., Alberto, W., Villa, F., Martelli, D., Salvalai, G., and Perotti, L.: Climate change and cryosphere in high mountains: preliminary results of field monitoring at Capanna Margherita hut, Punta Gnifetti (Monte Rosa, Pennine Alps), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20375, https://doi.org/10.5194/egusphere-egu2020-20375, 2020.

Alpine glacier retreat due to global warming generates major landscape changes in high mountain environments. New lakes can potentially form in Glaciers Bed Overdeepenings (GBOs). Those new water bodies, sometimes located near potentially instable slopes or behind unstable moraine dams, can increase outburst flood hazards, generating risks for valley floors. Such GLOF events (Glacial Lake Outbrust Floods) can result from displacement waves triggered by rock fall into lakes and/or sudden dam breaching. Those events can travel far down to low altitude areas and turning into high magnitude debris flows. Beyond the threats, those lakes can also represent opportunities for tourism, hydropower production or fresh water supply.

Anticipating location and formation of potential future lakes is thus essential for risk mitigation and seizing the opportunities. In the French Alps so far, potential future lakes have only been investigated in the Mont Blanc massif, while several other glaciated high mountain ranges may also yield water bodies in the near future. This study aims to identify and characterize the location of potential future lakes for each mountain massif of the French Alps (mainly the Mont Blanc, Grandes Rousses, Vanoise and Écrins massifs).

To do so, we first ran GlabTop model, a GIS scheme calculating ice thickness from surface slope via basal shear stress, to map potential GBOs. We also ran GlabTOP 2, which is based on the same concept but is fully automated. In this study, we compared the results between GlabTop and GlabTop 2. We then estimated the level of confidence of the predicted GBOs using morphometric analysis (slope angle at GBOs and downstream, presence/absence of crevasse fields, presence/absence of bedrock threshold) and classification of lakes according to their susceptibility of formation.

GlabTOP output thus revealed 89 GBOs (>1ha) which can potentially be sites for future lakes. 20 lakes are predicted in Écrins, 2 in Grandes Rousses, 39 in Vanoise and 30 on the French side of the Mont Blanc massif. The lakes with the highest surfaces/thicknesses are situated in the latter. Among the 89 predicted water bodies, 41 are highly susceptible to be formed. Some can already be observed in GBOs in recently deglaciated areas like at the Bionnassay and Tré la Tête glaciers (Mont Blanc massif).

This communication will present the approach, the detailed results and possible implications for landscape management at the French Alps scale.

How to cite: Cathala, M., Magnin, F., Linsbauer, A., Haeberli, W., Ravanel, L., and Deline, P.: Modelling glaciers bed overdeepenings and possible future lakes in deglaciating landscapes of the French Alps, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21229, https://doi.org/10.5194/egusphere-egu2020-21229, 2020.