Coastal erosion and mass wasting along the Canadian Beaufort Sea based on annual airborne LiDAR elevation data

• Published in: Geomorphology
• Main Authors: Obu, Jaroslav, Lantuit, Hugues, Grosse, Guido, Günther, Frank, Sachs, Torsten, Helm, Veit, Fritz, Michael
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: ELSEVIER SCIENCE BV 2017
• Subjects: Beaufort Sea; Herschel; Herschel Island; permafrost; Yukon
• Online Access: https://epic.awi.de/id/eprint/40240/; https://epic.awi.de/id/eprint/40240/1/1-s20-S0169555X16300502-main.pdf; https://hdl.handle.net/10013/epic.47349; https://hdl.handle.net/10013/epic.47349.d001

Erosion of permafrost coasts has received increasing scientific attention since 1990s because of rapid land loss and the mobilisation potential of old organic carbon. The majority of permafrost coastal erosion studies are limited to time periods from a few years to decades. Most of these studies emphasize the spatial variability of coastal erosion, but the intensity of inter-annual variations, including intermediate coastal aggradation, remains poorly documented. We used repeat airborne Light Detection And Ranging (LiDAR) elevation data from 2012 and 2013 with 1 m horizontal resolution to study coastal erosion and accompanying mass-wasting processes in the hinterland. Study sites were selected to include different morphologies along the coast of the Yukon Coastal Plain and on Herschel Island. We studied elevation and volume changes and coastline movement and compared the results between geomorphic units. Results showed simple uniform coastal erosion from low coasts (up to 10 m height) and a highly diverse erosion pattern along coasts with higher backshore elevation. This variability was particularly pronounced in the case of active retrogressive thaw slumps, which can decrease coastal erosion or even cause temporary progradation by sediment release. Most of the extremes were recorded in study sites with active slumping (e.g. 22 m of coastline retreat and 42 m of coastline progradation). Coastline progradation also resulted from the accumulation of slope collapse material. These occasional events can significantly affect the coastline position on a specific date and can affect coastal retreat rates as estimated in long term by coastline digitalisation from air photos and satellite imagery. These deficiencies can be overcome by short-term airborne LiDAR measurements, which provide detailed and high-resolution information about quickly changing elevations in coastal areas.