Exposed! Paraglacial Drama Unfolding at Hørbyebreen, Central Svalbard

Central Svalbard experiences one of the fastest warming trends in the Arctic and local glaciers are consequently retreating fast leaving behind vast forefields. As the glacier is not in the vicinity, it is not the glaciers that transforms the forefield but the paraglacial processes that work to continuously reshape them.

Here, we studied paraglacial processes in the Hørbye forefield by quantifying changes in the glacier extent, forefield geomorphology and formation/ drainage of the kettle lakes of the Hørbye glacier since the last mapping conducted in 2009. Aerial photography, UAV-based orthophotos and DEMs and field observations were employed to interpret forefield development.

Results of the study show an increased forefield size of Hørbyebreen since the last mapping in 2009.  The glacier has treated by 101237.4 m². The area of the kettle lakes underwent a net decrease, with 68% of the total lakes either being drained, shrinking, or disappearing entirely due to sediment infilling from the fluvial plain. We also observed fluvial erosion of glacial landforms such as eskers.

Understanding these changes highlight the central role of paraglacial processes in post-retreat development. As the glacier moves to steeper topography, the retreat is expected to slow down, although the glacier will continue to provide enough water for intensive fluvial processes in the forefield. Widening of the sandur will lead to lateral erosion of the lakes in its vicinity. For the rest of the forefield, hydrological connectivity can reshape the existing network of lakes.

The changes observed between 2009-2024 show the retreat of the glacier front and changes in the geomorphological structures of the forefield. We observed a decline in the number of lakes and increase in the areal extent of the fluvial landforms.