engleski

The application of remote sensing for monitoring the morphological changes of Ploče beach in Rijeka

Unmanned aerial vehicles (UAVs) have been used for coastal research in Croatia since 2012. SfM-MVS photogrammetry is mostly used for analysis of changes on beaches, which increasingly requires high resolution and precision of three-dimensional point clouds resulting from photogrammetric technique [1]. In this paper, this technology was used to study coastal processes on Ploče beach in Rijeka. The beach was surveyed 19 times with a drone in 2020 and 2021, and two 3D scans of the beach area were performed to determine the accuracy of the point clouds. The defined point cloud precision for the emerged beach is better than ± 5 cm. The point cloud representing the submerged beach was compared to the multibeam echo sounder data, and the results showed significantly greater discrepancies than for the emerged beach. The accuracy of the submerged point cloud data was increased by depth correction using the light refractive index, but more accurate corrections are one of the ultimate goals of this research. The CloudCompare software has also proven to be a useful tool for identifying and describing beach surface changes. Successive beach surveys were compared and digital models of the differences (DoDs) were created as a result. The comparisons showed that the greatest changes on the beach are caused by waves from southern and southeastern directions, and when storm events are accompanied by higher rainfall, runoff from coastal springs enhances the coastal process on the beach body. UAV photogrammetry has proven to be a simple, fast, and cost-effective tool for describing and visualising changes on beaches, considering that the morphological changes under the influence of waves and precipitation are much greater than the accuracy achieved.

beach erosion ; SfM photogrammetry ; point cloud ; digital elevation model

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