Coast formation in an Arctic area due to glacier surge and retreat: The Hornbreen–Hambergbreen case from Spistbergen

Abstract

Glacierised coasts undergo faster geomorphic processes than unglaciated ones. We have studied changes of the coastal area in southern Svalbard with the glacier bridge between Torell Land and Sørkapp Land since the beginning of the 20th century. The existence of a continuous subglacial depression beneath the Hornbreen–Hambergbreen glacier system has been debated since the 1960s, with inconclusive results. In this study we assess both the subglacial topography and the bathymetry of Hornsund Fjord and Hambergbukta bay. This included ~40 km of radar surveys over the glacial system and sea depth sounding. The extent of the glaciers from maps and satellite images together with digital terrain models and surface elevation data based on GPS profiling were used to analyse geometry changes of the glacier surfaces. The results confirm the existence of a continuous subglacial depression below sea level (c. 40 m deep) between Hornsund and the Barents Sea. The Hornbreen‐Hambergbreen system has changed in shape over the past century, reflecting its dynamic origin and activity, also exemplified by the sequential surges identified since 1899. There was a pre‐surge build‐up event of Flatbreen causing a surge and subsequent lowering of the Hornbreen‐Hambergbreen frontal parts by the 1960s. After, the entire surface lowered, albeit with a delay in the Hornbreen terminal zone. Since the year 2000, Hornbreen terminus has retreated at an average rate of 106 m a−1; ~50% faster than that of Hambergbreen. If the retreat continues at the 2000–2015 average rate, the ice bridge between Hornsund and Hambergbukta will be broken sometime between 2055 and 2065 and the Hornsund strait will separate Sørkapp Land from the Spitsbergen island. The processes and events described in this study, particularly the effects of the glacier surge, may provide a model for changes likely to occur in other coastal glaciated regions experiencing rapid change. Copyright © 2017 John Wiley & Sons, Ltd.

The Ice‐Free Topography of Svalbard

“…For the whole of Svalbard, we find that 13% of the glacierized area is grounded below sea level. Our results support the speculation that Sørkapp is a potential island separated by an ocean channel beneath Hornbreen and Hambergbreen (Grabiec et al, ). At present, the shallowest portion is covered by 180‐m‐thick ice.…”

Paraglacial coasts responses to glacier retreat and associated shifts in river floodplains over decadal timescales (1966–2016), Kongsfjorden, Svalbard

“…Terrigenous sediment input permits the formation of a subaqueous platform and the progradation of new coastal spit systems of more than 150 m in length seaward in a centennial timescale (Strzelecki et al, ). In South Spitsbergen, the retreat of the Hornbreen and its former tributaries (Hyrnebreen, Storbreen, Svalisbreen, Meddeleevbreen, and Chomjakovbreen) has contributed to the creation of Brepollen, the inner part of the Hornsund fjord (Grabiec et al, ). In Sørkapp, south‐eastern Spitsbergen, the front of three glaciers (Coryellebreen, Bevanbreen, and Kambreen) retreated by 600–800 m between 1936 and 2005 thereby generating large landscape modifications.…”

New fjords, new coasts, new landscapes: The geomorphology of paraglacial coasts formed after recent glacier retreat in Brepollen (Hornsund, southern Svalbard)

“…In nearby Hornsund the tides have an average amplitude of 0.75 m (Herman et al, 2019). Based on bathymetric profile interpolation, Moskalik et al (2013) divided the new bay into eight sub-basins, six of which consist of glacier valleys (Storbreen, Hornbreen, Svalisbreen, Mendelejevbreen, Chomjakovbreen and Hyrnebreen); one separate cove along the eastern shore of Treskelen; and one central open-water part which constitutes~30% of the bay area and has maximum water depths in excess of 140 m. The recent retreat of Hornbreen/Hambergbreen has also revealed evidence for a submerged channel Ostafin, 2014, 2019;Grabiec et al, 2018). Radar surveys across Hornbreen/Hambergbreen carried out by Grabiec et al (2018) revealed a 40 m-deep subglacial channel that, by 2055-2065, may evolve into a strait linking the Greenland and Barents seas (Brepollen and Hambergbukta, respectively) if current glacier retreat rates remain unchanged ( Figure 2).…”