Detection of retrogressive thaw slumps using TanDEM-X observations: Possibilities and limitations

Inhalt:
When ice-rich permafrost soil thaws it becomes unstable, leading to changes in the topography. The most rapid and dramatic changes occur due to retrogressive thaw slumps. These slumps evolve by a retreat of the slump headwall during the summer months, making them detectable by comparing digital elevation models over time. Here we present results of a retrogressive thaw slump detection method using bistatic single-pass radar observation from the TanDEM-X satellite pair over the time span from 2010 to 2017 applied on two contrasting study areas in Northern Canada, located in the Mackenzie River Δ and on Banks Island. Our processing chain include the digital elevation generation process, elevation model differencing, water body mask generation and a method for the detection of significant height changes. We analyse if the generated elevation models have high enough resolution to be used for retrogressive thaw slump detection and investigate the dependency on the time of the year when the observations were obtained. Our results indicate that the obtained elevation models can be used for thaw slump detection, but observations generated in the spring and summer month show large errors related to vegetation and snow and significantly increased the number of false detections.