EGU22-9799
https://doi.org/10.5194/egusphere-egu22-9799
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Coastal erosion dynamics of high-Arctic rock walls: insights from historical to recent orthoimages and DEMs 

Juditha Aga1, Livia Piermattei1, Luc Girod1, and Sebastian Westermann1,2
Juditha Aga et al.
  • 1University of Oslo, Mathematics and Natural Sciences, Geosciences, Oslo, Norway
  • 2Center for Biogeochemistry in the Anthropocene, University of Oslo, Norway

The thermal regime of permafrost, as well as the retreat of sea ice, influence coastal erosion in Arctic environments. Warming permafrost temperatures might lead to enhanced instabilities, while shorter periods of sea ice expose coastal cliffs to waves and tides for longer periods. Although most studies focus on erosion rates in ice-rich permafrost, coastal cliffs and their permafrost thermal regime are still poorly understood.

In this study, we investigate the long-term evolution of the coastline along Brøgger Peninsula (~30 km2), Svalbard. Based on high-resolution aerial orthophotos and, when available, digital elevation model (DEMs) we automatically derive the coastline from 1936 (Geyman et al., 2021), 1970, 1990, 2011 and 2021. Therefore, we quantified coastal erosion rates along the coastal cliffs over the last 85 years. Due to their high spatial resolution and accuracy, the two DEMs from 1970 and 2021 are used to calculate the erosion volumes within this time. Elevation data and coastline mapping from 2021 is validated with dGPS measurements from August 2021 along three transects of the coastline. In addition, we measured surface temperature of the coastal bedrock from September 2020 to August 2021.

Our preliminary results show erosion rates along the coastal cliffs of Brøgger Peninsula. Uncertainties remain due to mapping issues, which include resolution of aerial images and DEMs, and shadow effects. Overall, historical aerial images combined with recent data provide insight into coastal evolution in an Arctic environment where permafrost temperatures are close to the thaw threshold and might become prone to failure in future.

 

Geyman, E., van Pelt, W., Maloof, A., Aas, H. F., & Kohler, J. (2021). 1936/1938 DEM of Svalbard [Data set]. Norwegian Polar Institute. https://doi.org/10.21334/npolar.2021.f6afca5c

How to cite: Aga, J., Piermattei, L., Girod, L., and Westermann, S.: Coastal erosion dynamics of high-Arctic rock walls: insights from historical to recent orthoimages and DEMs , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9799, https://doi.org/10.5194/egusphere-egu22-9799, 2022.