Subglacial Landscape of Folgefonna (Norway) Indicate Significant Hydrological Changes in a Future Ice-free Environment

Here we present a new high resolution subglacial topography map of the plateau glacier Folgefonna in South West Norway based on ice radar data collected with a 2.5 Mhz antenna. The glacier is located in a national park close to urban communities and it is important for hydropower production. The map provides new information on hydrological changes and potential natural hazard areas emerging from a retreating glacier.

To find glacier depth we used radar technology with a Blue System Integration radar set up (2.5 MHz antenna) over four field seasons (2015-2018). GIS-software was used to interpolate a map from the depth measurements.

The result shows a thicker glacier than anticipated (maximum depth 570 m) while the total volume estimates (28 km³) are close to previous calculations based on average depth interpolations. The map reveals that the majority of precipitation and snowmelt will drain south in a future non-glaciated landscape. This can impact hydropower constructions already during the retreating phase of the glacier and will change the sizes of current drainage catchments.

This study suggests that increased monitoring of the glacier is required in order to ensure the safety of local communities. Nearby infrastructure will most likely be affected by the glacier retreat, as hazards such as Glacial Outburst Floods, mass wasting movements and floods are expected to occur more frequently. The new subglacial topography map provides a good base for modelling future retreat scenarios of the glacier. The result will in turn enable the development of solid regional research-based adaptation strategies.