Remote sensing and mapping of geomorphological features in Hanaskogdalen, Svalbard

Abstract

Formerly glaciated areas still under the influence of retreating glaciers, also referred to as paraglacial environments, are sensitive to climatic changes. This manifests in the alteration of geomorphological processes. Already, Arctic settlements like Longyearbyen (Svalbard, Norway) are increasingly threatened by landslides and coastal erosion. Facing the concerns of environmental change in the Arctic, this study investigates trends in the geomorphological regimes of the western Spitsbergen valley of Hanaskogdalen (Svalbard, Norway). Therefore, a set of five airborne images from the years 1936, 1961, 1990, 2008, and 2020, as well as two digital surface models from 2008 and 2020, were used to map different surface processes in QGIS. These included the loss of ice-covered area and volume changes of the glacier Brandtbreen, coastline changes, debris flow volumes and frequency, as well as the occurrence and extent of active layer-detachment slides. The results revealed changing patterns, particularly accelerations in the more recent images. Glacial ice-covered area was lost increasingly, with volume losses fitting well within the rates of other Svalbard glaciers. Overall, Hanaskogdalen’s coastline retreated except for the central part, where a river formed an alluvial fan. Debris flows changed from a transport-limited system to being more frequent yet less voluminous. Finally, a whole series of active-layer detachment slides occurred on the recently exposed moraines of Brandtbreen. Airborne data and GIS mapping proved to be an accurate and versatile tool, especially in newer images. The findings are in agreement with the anticipated effects of global warming on the observed geomorphological features, underlining the vulnerability of Arctic environments.