Abstract
Landslide mapping and analysis are essential aspects of hazard and risk analysis. Landslides can block rivers and create landslide-dammed lakes, which pose a significant risk for downstream areas. In this research, we used an object-based image analysis approach to map geomorphological features and related changes and assess the applicability of Sentinel-1 data for the fast creation of post-event digital elevation models (DEMs) for landslide volume estimation. We investigated the Hítardalur landslide, which occurred on the 7 July 2018 in western Iceland, along with the geomorphological changes induced by this landslide, using optical and synthetic aperture radar data from Sentinel-2 and Sentinel-1. The results show that there were no considerable changes in the landslide area between 2018 and 2019. However, the landslide-dammed lake area shrunk between 2018 and 2019. Moreover, the Hítará river diverted its course as a result of the landslide. The DEMs, generated by ascending and descending flight directions and three orbits, and the subsequent volume estimation revealed that—without further post-processing—the results need to be interpreted with care since several factors influence the DEM generation from Sentinel-1 imagery.
Highlights
Landslide mapping and analysis are essential aspects of hazard and risk analysis, and the accurate detection of land surface changes is crucial for understanding processes and interactions between human and natural phenomena [1,2]
The water flowing out of the dammed lake found a new route through a lava field towards the south and merged with the Stekka river, resulting in more water flowing in this riverbed than prior to the landslide
The upper part of the connection between the lake and the Stekka river is not distinguishable in the Sentinel-2 image taken in August 2019, probably due to less water flowing there at the time of the image acquisition one month later in the year 2019 (July 2018 versus August 2019)
Summary
Landslide mapping and analysis are essential aspects of hazard and risk analysis, and the accurate detection of land surface changes is crucial for understanding processes and interactions between human and natural phenomena [1,2]. Rapid mass movements are a common geomorphological process in Iceland and represent a significant threat to people and infrastructure [4,5,6]. Examples of such landslides are a rock avalanche onto the Morsárjökull outlet glacier in 2007 [7], a debris slide at the Móafellshyrna Mountain in northern Iceland in 2012 [8], and the landslide at the Askja caldera in July. Earth Observation (EO) data from optical and synthetic aperture radar (SAR) sensors have proven valuable for mapping and monitoring geomorphological features and, in particular, different types of landslides [1,12,13,14]. Optical imagery from different sources such as satellites, or unmanned aerial
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