UAV-based remote sensing of immediate changes in geomorphology following a glacial lake outburst flood at the Zackenberg river, northeast Greenland

Abstract

Two detailed geomorphological maps (1:2000) depicting landscape changes as a result of a glacial lake outburst flood were produced for the 2.1-km-long section of the Zackenberg river, NE Greenland. The maps document the riverscape before the flood (5 August 2017) and immediately after the flood (8 August 2017), illustrating changes to the riverbanks and morphology of the channel. A series of additional maps (1:800) represent case studies of different types of riverbank responses, emphasising the importance of the lateral thermoerosion and bank collapsing as significant immediate effects of the flood. The average channel width increased from 40.75 m pre-flood to 44.59 m post-flood, whereas the length of active riverbanks decreased from 1729 to 1657 m. The new deposits related to 2017 flood covered 93,702 m 2. The developed maps demonstrated the applicability of small Unmanned Aerial Vehicles (UAVs) for investigating the direct effects of floods, even in the harsh Arctic environment.

Geomorphological impacts of a glacier lake outburst flood in the high arctic Zackenberg River, NE Greenland

“…Our data indicate that, in most sections, the one-day flood in 2017 caused a larger bank erosion than changes in the 2014-2017 period. This situation came about despite the fact that in 2014, 2015 and 2016 the flood had regularly occurred in late summer (July-August) and that the maximum discharges of the Zackenberg River were then higher than during the 2017 flood (Tomczyk and Ewertowski, 2020).…”

“…The flood event lasted approximately 24 h. Although the size of the flood was not very large compared to previous GLOFs, it caused significant changes to the riverscape morphology. Detailed geomorphological maps showing the spatial pattern of the river's immediate geomorphological response to this flood are presented in Tomczyk and Ewertowski (2020).…”

“…Overall, these speculations contend that despite a similar magnitude flood down a river water levels of subsequent floods will become higher, thereby exacerbating geomorphological impact and perhaps also permafrost losses. Tomczyk and Ewertowski, 2020).…”

Reconstructing glacial outburst floods (jökulhlaups) from geomorphology: Challenges, solutions, and an enhanced interpretive framework

“…Notable examples include mapping sandur evolution after jökulhlaups from the 2010 Eyjafjallajökull subglacial eruption in south Iceland (Dunning et al, 2013; Harrison et al, 2019) and river channel changes from glacial outburst floods in the Nepal Himalayas (Cook et al, 2018) and northeast Greenland (Tomczyk et al, 2020). Additionally, these imaging tools can be mounted on drones or unmanned aerial vehicles (UAVs) to provide a relatively affordable, portable, self-operable, and spatially tailored mode of data collection (Chandler et al, 2018; Tomczyk and Ewertowski, 2020).…”

Evaluation of the Influence of Processing Parameters in Structure-from-Motion Software on the Quality of Digital Elevation Models and Orthomosaics in the Context of Studies on Earth Surface Dynamics

“…As a result, first a sparse, and then a dense point cloud is obtained, which is the basis for generating the final photogrammetric products. A DEM, which is a three-dimensional model of the studied area's surface and orthomosaic, is commonly used for analyses related to geomorphological mapping (e.g., [22,28,[40][41][42]), change detection (e.g., [38,[43][44][45]), process-form studies [46] or mapping of surficial geology [47]. Evidence of the common use of UAV and the SfM method in geomorphology consists of publications in which the authors present the appropriate workflow of conduct during field research and in the further preparation of publications and presentation of results (e.g., [48][49][50]).…”