Inventory and classification of the post Little Ice Age glacial lakes in Svalbard

Rapid changes of glacial lakes are among the most visible indicators of global warming in glacierized areas around the world. The general trend is that the area and number of glacial lakes increase significantly in high mountain areas and polar latitudes. However, there is a lack of knowledge about the current state of glacial lakes in the High Arctic. This study aims to address this issue by providing the first glacial lake inventory from Svalbard, with focus on the genesis and evolution of glacial lakes since the end of the Little Ice Age. We use aerial photographs and topographic data from 1936 to 2012 and satellite imagery from 2013 to 2020. The inventory includes the development of 566 glacial lakes (total area of 145.91 km2) that were in direct contact with glaciers in 2008–2012. From the 1990s to the end of the 2000s, the total glacial lake area increased by nearly a factor of six. A decrease in the number of lakes between 2012 and 2020 is related to two main processes: the drainage of 197 lakes and the merger of smaller reservoirs into larger ones. The changes of glacial lakes show how climate change in the High Arctic affect proglacial geomorphology by enhanced formation of glacial lakes, leading to higher risks associated with glacier lake outburst floods in Svalbard.

Dynamics of Lower-Barun Glacier and Glacial Lake and its GLOF Susceptibility Using Geospatial Analysis and Modelling

Shrinkage of some of the glaciers has direct impacts on the formation and expansion of glacial lakes. Sudden glacial lake outburst floods (GLOFs) are a major threat to lives and livelihoods downstream as they can cause catastrophic damage. In this study, we present the dynamics of the Lower-Barun glacier and glacial lakes and their GLOF susceptibility. We used multi temporal Landsat and Sentinel satellite imagery and extracted the lake outlines using the Normalized Difference Water Index (NDWI) with manual post-correction while the glacier outline was digitized manually. Multi-criteria decision-based method was used to assess the GLOF susceptibility. For the estimation of peak discharge and failure time, an empirical model developed by Froelich (1995) was used. The surface area of the Lower-Barun glacial lake was increased by 86% in the last 40 yrs (from 1979 to 2018), with a mean increase of 0.0432 km2/yr. The shrinkage in the glacier area is around 0.49 km2/yr and has shrunk by 8% in the last four decades. The retreat of the Lower-Barun glacier was 0.20% per year in the last four decades. The susceptibility index was 0.94, which suggests that the lake is very highly susceptible to the GLOF. The peak discharge of 5768 m3/s is produced when the breach depth is 20 m and the entire water volume is released. Likewise, in the case of 15 m breach depth, the peak discharge of 4038 m3/s is formed. Breach depth scenario of 10 m, peak discharge of 2442 m3/s is produced and in case of breach depth of 5 m produces the peak discharge of 1034 m3/s. If GLOF occurs, it can exert disastrous impacts on the livelihood and infrastructure in the downstream. So, it is necessary to examine such lakes regularly and mitigation measures to lower the GLOF susceptibility should be emphasized.

Run! The Mountain Is Coming!

This chapter explains the dynamics of Glacier Lake Outburst Floods (GLOFs) or glacier tsunamis. It describes how climate change and resulting global warming is destabilizing high mountain glaciers perched above deep glacier lakes formed by receding glaciers and subsequent melting. The chapter goes on to explain how the collapse of large pieces of ice result in mountain top born tsunami waves that destroy downstream ecosystems, people, and infrastructure and how climate change is raising the likelihood that these glacier tsunamis will occur throughout the world. It recounts historical GLOF events throughout the world, detailing the impacts and risks of these tragic events.

Hazardous geomorphic processes in the extratropical Andes with a focus on glacial lake outburst floods

<p>This study examines hazardous processes and events originating from glacier and permafrost areas in the extratropical Andes (Andes of Chile and Argentina) in order to document their frequency, magnitude, dynamics and their geomorphic and societal impacts. Ice-avalanches and rock-falls from permafrost areas, lahars from ice-capped volcanoes and glacial lake outburst floods (GLOFs) have occurred in the extratropical Andes causing ~200 human deaths in the Twentieth Century. However, data about these events is scarce and has not been studied systematically. Thus, a better knowledge of glacier and permafrost hazards in the extratropical Andes is required to better prepare for threats emerging from a rapidly evolving cryosphere. I carried out a regional-scale review of hazardous processes and events originating in glacier and permafrost areas in the extratropical Andes. This review, developed by means of a bibliographic analysis and the interpretation of satellite images, shows that multi-phase mass movements involving glaciers and permafrost and lahars have caused damage to communities in the extratropical Andes. However, it is noted that GLOFs are one the most common and far reaching hazards and that GLOFs in this region include some of the most voluminous GLOFs in historical time on Earth. Furthermore, GLOF hazard is likely to increase in the future in response to glacier retreat and lake development. To gain insight into the dynamics of GLOFs I create a regional-scale inventory of glacier lakes and associated hazards in the Baker Basin, a 20500 km2 glaciated basin in the Chilean Patagonia. I also simulate and reconstruct moraine- and ice- dammed lake failures in the extratropical Andes using numerical and empirical models. More than 100 GLOFs have occurred in the extratropical Andes since the Eighteenth Century and at least 16 moraine-dammed lakes have produced GLOFs. In the extratropical Andes most of the failed moraine-dammed lakes were in contact with retreating glaciers and had moderate (> 8°) to steep (>15°) outlet slopes. Ice-dammed lakes also produced GLOFs in the extratropical Andes, damaging communities and highlighting the need for a better understanding of the GLOF dynamics and hazards. Thus, I reconstruct and model GLOFs that occurred in maritime western Patagonia (Engaño Valley) and the high-arid Andes (Manflas Valley) to characterise the GLOF dynamics in these contrasting environments. Hydraulic modelling and geomorphologic analysis shows that the Engaño River GLOF (46º S) behaved as a Newtonian flow and incorporated tree trunks, from the gently sloping and heavily-forested valley, which increased the GLOF damaging capacity. In contrast, the Manflas GLOF (28º S) descended from a steep valley behaving as a sediment-laden flow, which was capable of moving boulder-size rocks dozens of kilometres from the GLOF source. In both events lack of awareness of the GLOF hazard and a lack of territorial planning accentuated the GLOF damage. These GLOF reconstructions highlight both the difficulties in modelling sediment-laden flows over long distances, and the utility of empirical debris-flow models for regional-scale hazard analysis. This thesis synthesises and increases our knowledge about the distribution, frequency, magnitude and dynamics of hazardous processes that have occurred in glacier and permafrost areas in the extratropical Andes. This knowledge forms a basis for future assessments of glacier and permafrost related hazards in the Chilean and Argentinean Andes and helps inform strategies and policies to face hazardous geomorphologic and hydrological processes emerging from a rapidly evolving cryosphere.</p>

Hazardous geomorphic processes in the extratropical Andes with a focus on glacial lake outburst floods

<p>This study examines hazardous processes and events originating from glacier and permafrost areas in the extratropical Andes (Andes of Chile and Argentina) in order to document their frequency, magnitude, dynamics and their geomorphic and societal impacts. Ice-avalanches and rock-falls from permafrost areas, lahars from ice-capped volcanoes and glacial lake outburst floods (GLOFs) have occurred in the extratropical Andes causing ~200 human deaths in the Twentieth Century. However, data about these events is scarce and has not been studied systematically. Thus, a better knowledge of glacier and permafrost hazards in the extratropical Andes is required to better prepare for threats emerging from a rapidly evolving cryosphere. I carried out a regional-scale review of hazardous processes and events originating in glacier and permafrost areas in the extratropical Andes. This review, developed by means of a bibliographic analysis and the interpretation of satellite images, shows that multi-phase mass movements involving glaciers and permafrost and lahars have caused damage to communities in the extratropical Andes. However, it is noted that GLOFs are one the most common and far reaching hazards and that GLOFs in this region include some of the most voluminous GLOFs in historical time on Earth. Furthermore, GLOF hazard is likely to increase in the future in response to glacier retreat and lake development. To gain insight into the dynamics of GLOFs I create a regional-scale inventory of glacier lakes and associated hazards in the Baker Basin, a 20500 km2 glaciated basin in the Chilean Patagonia. I also simulate and reconstruct moraine- and ice- dammed lake failures in the extratropical Andes using numerical and empirical models. More than 100 GLOFs have occurred in the extratropical Andes since the Eighteenth Century and at least 16 moraine-dammed lakes have produced GLOFs. In the extratropical Andes most of the failed moraine-dammed lakes were in contact with retreating glaciers and had moderate (> 8°) to steep (>15°) outlet slopes. Ice-dammed lakes also produced GLOFs in the extratropical Andes, damaging communities and highlighting the need for a better understanding of the GLOF dynamics and hazards. Thus, I reconstruct and model GLOFs that occurred in maritime western Patagonia (Engaño Valley) and the high-arid Andes (Manflas Valley) to characterise the GLOF dynamics in these contrasting environments. Hydraulic modelling and geomorphologic analysis shows that the Engaño River GLOF (46º S) behaved as a Newtonian flow and incorporated tree trunks, from the gently sloping and heavily-forested valley, which increased the GLOF damaging capacity. In contrast, the Manflas GLOF (28º S) descended from a steep valley behaving as a sediment-laden flow, which was capable of moving boulder-size rocks dozens of kilometres from the GLOF source. In both events lack of awareness of the GLOF hazard and a lack of territorial planning accentuated the GLOF damage. These GLOF reconstructions highlight both the difficulties in modelling sediment-laden flows over long distances, and the utility of empirical debris-flow models for regional-scale hazard analysis. This thesis synthesises and increases our knowledge about the distribution, frequency, magnitude and dynamics of hazardous processes that have occurred in glacier and permafrost areas in the extratropical Andes. This knowledge forms a basis for future assessments of glacier and permafrost related hazards in the Chilean and Argentinean Andes and helps inform strategies and policies to face hazardous geomorphologic and hydrological processes emerging from a rapidly evolving cryosphere.</p>

Baseline data for monitoring geomorphological effects of glacier lake outburst flood: a very-high-resolution image and GIS datasets of the distal part of the Zackenberg River, northeast Greenland

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