Accuracy of the UAV-Based DEM of Beach–Foredune Topography in Relation to Selected Morphometric Variables, Land Cover, and Multitemporal Sediment Budget

Abstract

Recent developments in unmanned aerial vehicles (UAVs) have resulted in high-resolution digital elevation models (DEMs) of vulnerable coastal environments, including beach–foredune topography. If performed repetitively, they can offer an excellent tool to determine the spatial and temporal changes in the sediment budget, which may be required for proper land management. However, the quality of a UAV, slope parameters, and vegetation significantly influence DEM accuracy. The aim of this study is to compare precise GPS-RTK transects across a section of the South Baltic coast in Poland with those obtained from a DEM based on high-resolution and high-accuracy images obtained by a wind-resistant, high-quality fixed-wing UAV during beyond visual line of sight operation (BVLOS). Different land cover classes, slope inclination, and general curvature, as well as surface roughness, were taken into consideration as possible factors influencing the uncertainty. The study revealed that marram grass greatly affects the accuracy of the UAV-derived model and that the uncertainty of the UAV-derived DEM increases together with increasing slope inclination and, to a lesser degree, with increasing general slope curvature. We showed that sediment budget determinations with the use of a UAV-based DEM are correct only where grass cover is sparse, in our study, up to 20% of the area.

Assessing geomorphic change in restored coastal dune ecosystems using a multi-platform aerial approach

“…Our UAS-TLS comparisons featured lower residuals than the KAP-TLS comparison, however there were still consistent differences between the two platforms. Similar to findings by Mancini et al [8], Guisado-Pintado et al [32], and Rotnicka et al [80], our comparison found that the locations of highest variability were located within the beach unit, particularly where wet and relatively featureless sand was present, as well as in areas of dense vegetation, particularly in the AMM plot. We also note that two of the highest residuals were across the seaward slope of the foredune and corresponded with spring acquisition campaigns when the seaward slope was scarped, suggesting that, as discussed by James et al [78], topographic complexity played a role in limiting the number of convergent points for surface reconstruction on steep slopes.…”

“…Bangen et al [82] built on that and discussed uncertainty budget development and error propagation, suggesting that error could be introduced by survey methods, sampling strategy, and surface complexity. In the context of the coastal zone, variability and possible sources of uncertainty could even extend to weather, tidal, and moisture conditions or seasonal variability in the complexity of the terrain or vegetation cover [32,80].…”

Integrated Remote Sensing to Assess Disease Control: Evidence from Flat Island Quarantine Station, Mauritius

“…Our latest acquisition was an exceptional 1949 aerial image that displays good visibility and preservation of the station's infrastructure almost a century ago (Figure 6). The production of a detailed three-dimensional map of the landscape, and the immediate seascape of the island with its reef and coastal environment using UAV images and HD video from the entire island, is ongoing and should be completed by 2023 [39]. Nevertheless, the aerial photographs provided by drones have been crucial to the research team on the ground, helping us better understand the connections between different zones of the station.…”

“…By overlaying various historical maps with current images-from the detailed plan of the quarantine island of 1857 by the government surveyor Thomas Corby (Figure 7) to its construction and current state corroborated on the ground-we aim to present a diachronic sequence of detailed maps of the quarantine island from the various decades of the 19th through the 20th century. The map produced so far illustrates the The production of a detailed three-dimensional map of the landscape, and the immediate seascape of the island with its reef and coastal environment using UAV images and HD video from the entire island, is ongoing and should be completed by 2023 [39]. Nevertheless, the aerial photographs provided by drones have been crucial to the research team on the ground, helping us better understand the connections between different zones of the station.…”

Landslide detection and characterization based on OBIA methodology and UAV photogrammetry

“…Even those accuracies can provide essential information for landslides in a cost-effective way. Previous research results have demonstrated that 3D landslide models generated by using UAV and SfM techniques have very high relative accuracy and, to a certain extent, can meet the requirements for preliminary field surveys of landslides without the establishment of GCPs (Casella et al 2020;Rotnicka et al 2020).…”