Preliminary assessment of thaw slump hazard to Arctic cultural heritage in Nordenskiöld Land, Svalbard

Permafrost-dependent landslides occur in a range of sizes and are among the most dynamic landforms in the Arctic in the warming climate. Retrogressive thaw slumps (RTSs) are enlarging landslides triggered by thawing and release of excess water from permafrost ground ice, causing smaller or larger collapses of ground surface, which in turn exposes new permafrost to rapid thawing and collapse. In this study, a preliminary assessment of previous thaw slump activity in Nordenskiöld Land area of Svalbard is made based on remote sensing digitisation of 400 slump-scar features from aerial images from the Norwegian Polar Institute (NPI). RTS properties and distribution are analysed with an emphasis on their implications for the preservation of the Svalbard’s cultural heritage (CH). Our analysis shows that the areas where RTS scars and CH co-exist in Nordenskiöld Land are, at present, limited and cover mainly areas distributed along north-west (Colesbukta, Grønfjorden, Kapp Starostin), north-east (Sassendalen and Sassenfjorden) and south-west (Van Muydenbukta) coastlines. Taking into consideration the preliminary aspect of this inventory and study, it can be stated that for now, RTS and CH sites do not have a high level of co-existence, except for eight sites which are located at less than 100 m to a RTS and one site that is located inside a currently inactive slump-scar. Further mapping of RTS will be undertaken in order to have a complete picture of these climate triggered landslides potentially threatening the Arctic CH. The results of this study, even if preliminary, can be used by local authorities and stakeholders in prioritising future documentation and mitigation measures and can thus present a powerful tool in disaster risk reduction

The geomorphological effect of cornice fall avalanches in the Longyeardalen valley, Svalbard

The study of snow avalanches and their geomorphological effect in the periglacial parts of the cryosphere is important for enhanced geomorphological process understanding as well as hazard-related studies. Only a few field studies, and particularly few in the High Arctic, have quantified avalanche sedimentation. Snow avalanches are traditionally ranked behind rockfall in terms of their significance for mass-wasting processes of rockslopes. Cornice fall avalanches are at present the most dominant snow avalanche type at two slope systems, called Nybyen and Larsbreen, in the valley Longyeardalen in central Svalbard. Both slope systems are on northwest-facing lee slopes underneath a large summit plateau, with annual cornices forming on the top. High-frequency and magnitude cornice fall avalanching is observed by daily automatic time-lapse photography. In addition, rock debris sedimentation by cornice fall avalanches was measured directly in permanent sediment traps or by snow inventories. The results from a maximum of seven years of measurements in a total of 13 catchments show maximum mean rock debris sedimentation rates ranging from 8.2 to 38.7 kg m⁻² at Nybyen, and from 0.8 to 55.4 kg m⁻² at Larsbreen. Correspondingly, avalanche fan surfaces accreted from 2.6 to 8.8 mm yr⁻¹ at Nybyen, and from 0.2 to 13.9 mm yr⁻¹ at Larsbreen. This comparably efficient rockslope mass wasting is due to collapsing cornices producing cornice fall avalanches containing large amounts of rock debris throughout the entire winter. The rock debris of different origin stems from the plateau crests, the adjacent free rock face and the transport pathway, accumulating distinct avalanche fans at both slope systems. Cornice fall avalanche sedimentation also contributed to the development of a rock glacier at the Larsbreen site during the Holocene. We have recorded present maximum rockwall retreat rates of 0.9 mm yr⁻¹ at Nybyen, but as much as 6.7 mm yr⁻¹ at Larsbreen, while average Holocene rockwall retreat rates of 1.1 mm yr⁻¹ at Nybyen have been determined earlier. As cornice fall avalanches are the dominant type of avalanche in central Svalbard, the related geomorphological effect is assumed to be of significance at periglacial landscape scale. A climate-induced shift in prevailing winter wind direction could change the rockslope sedimentation effectively by changing the snow avalanche activity

Debris flow modeling for susceptibility mapping at regional to national scale in Norway

Debris flows and related landslide processes occur in many regions all over Norway and pose a significant hazard to inhabited areas. Within the framework of the development of a national debris flows susceptibility map, we are working on a modeling approach suitable for Norway with a nationwide coverage. The discrimination of source areas is based on an index approach, which includes topographic parameters and hydrological settings. For the runout modeling, we use the Flow-R model (IGAR, University of Lausanne), which is based on combined probabilistic and energetic algorithms for the assessment of the spreading of the flow and maximum runout distances. First results for different test areas have shown that runout distances can be modeled reliably. For the selection of source areas, however, additional factors have to be considered, such as the lithological and quaternary geological setting, in order to accommodate the strong variation in debris flow activity in the different geological, geomorphological and climate regions of Norway

Surface morphology of fans in the high-Arctic periglacial environment of Svalbard: Controls and processes

Fan-shaped landforms occur in all climatic regions on Earth. They have been extensively studied in many of these regions, but there are few studies on fans in periglacial, Arctic and Antarctic regions. Fans in such regions are exposed to many site-specific environmental conditions in addition to their geological and topographic setting: there can be continuous to discontinuous permafrost and snow avalanches and freeze–thaw cycles can be frequent. We study fans in the high-Arctic environment of Svalbard to (1) increase our fundamental knowledge on the morphology and morphometry of fans in periglacial environments, and (2) to identify the specific influence of periglacial conditions on fans in these environments. Snow avalanches have a large geomorphic effect on fans on Svalbard: the morphology of colluvial fans is mainly determined by frequent snow avalanches (e.g., flattened cross-profiles, exposed fine-grained talus on the proximal fan domain, debris horns and tails). As a result, there are only few fans with a rockfall-dominated morphology, in contrast to most other regions on Earth. Slush avalanches contribute significant amounts of sediment to the studied alluvial fans. The inactive surfaces of many alluvial fans are rapidly beveled and leveled by snow avalanches, solifluction and frost weathering. Additionally, periglacial reworking of the fan surface often modifies the original morphology of inactive fan surfaces, for example by the formation of ice-wedge polygons and hummocks. Permafrost lowers the precipitation threshold for debris-flow initiation, but limits debris-flow volumes. Global warming-induced permafrost degradation will likely increase debris-flow activity and -magnitude on fans in periglacial environments. Geomorphic activity on snow avalanche-dominated colluvial fans will probably increase due to future increases in precipitation, but depends locally on climate-induced changes in dominant wind direction

Coastal change in Svalbard – filling a knowledge gap in Arctic response to climate change

International audienceThe coastline of the Svalbard archipelago is highly dynamic with known consequences for erosion of modern infrastructure as well as cultural heritage. Focus from natural and local management has mostly been on coastal erosion, but our work also documents lateral movement and progradation on the order of up to tens of meters per year, which has implications for sediment and nutrient transport to the fjords, wetland dynamics and vegetation. Until recently large-scale geomorphological mapping of the coastal environment in Svalbard was lacking and studies carried out were typically site-specific or focused on a particular depositional system making it difficult to compare trends with regional and pan-Arctic patterns.Here we present the results of a decade of site-studies in a range of inner fjord environments combined with large-scale remote sensing based mapping of coastal geomorphology, mapping of coastal processes and responses and tool development for quantification of horizontal change. Under the DynaCoast project, we mapped the geomorphology of the coastal zone of Isfjorden from the shoreline to 500 m inland. A key result from the DynaCoast map is that most segments of the Svalbard coastline are dominated by a combination of physical processes with particular morphological results. Change in for example glacier front locations, sea ice presence and duration, run off, and wave action create specific morphological signatures and can be traced in the landscape. Here we present the first map of coastal process classifications for the Svalbard archipelago and discuss the implications for predicting sensitivity to change or planning mitigation strategies. Quantification of horizontal change in real time is approached through use of satellite imagery and compared to historic records through use of digital elevation models with potential to study transects acrossSvalbard or regional trends

Development of multiple taliks near settlements on Svalbard – a new source of drinking water for the High Arctic?

This article presents a comprehensive documentation and analysis of long-term observations of year-round groundwater occurrences in rivers and various types of taliks under continuous permafrost conditions on Svalbard. Previously thought to be nonexistent, the existence of these taliks has been confirmed through rigorous field observations, geotechnical investigations, and extensive data collection. This discovery holds pivotal implications for our current understanding of permafrost conditions in central Svalbard. The research reveals the presence of several year-round taliks in close proximity to the settlements in Longyearbyen, Pyramiden, and Ny-Ålesund. Importantly, these findings open up opportunities for using these taliks as groundwater reservoirs for extraction of drinking water, either in natural state or with appropriate engineering modifications. Furthermore, climate change may the possibilities in future by expanding the size of these talik reservoirs due to rising air temperatures and increased inflow of fresh water over prolonged summer . The results underscore the importance of including river taliks in continuous permafrost areas in water management strategies for Svalbard and similar Arctic regions. This research not only challenges prior assumptions but also offers valuable insights for sustainable water resource utilization in a changing climate context