Synergy of UAV data and in situ measurements for the shoreline mapping in Arkoudi beach, Western Greece

Coastal areas are attractive for human populations as they are important areas of business and socio-economic activities. The Prefecture of Western Greece is experiencing population movement from the urban to the coastal areas causing nuisance and changes to the marine environment. These changes need to be assessed systematically in order to build models that can predict the evolution in the future. In addition, except for the man-made infrastructures, natural phenomena such as undulation, wind and coastal currents affect the shape of the beach, the shoreline and the seabed. Remote sensing is an efficient way to measure these changes repeatedly using high resolution satellite data, air photos and airborne Lidar in conjunction with Digital Surface Models (DSMs) and orthophoto maps. These methods have disadvantages as they are high cost, especially in cases where multitemporal data is deeded. Unmanned aerial vehicles (UAV) photogrammetry, offers a reliable alternative solution to the acquisition of high accuracy spatial data along the littoral zone, representing a rapid low-cost tool for coastline monitoring. In the present study, the littoral area of the bay of Arkoudi situated in the Prefecture of Ilia’s, Greece, has been used as test site. Repeated UAV campaigns were performed in 2020, 2021 and 2022 in synergy with extensive Global Navigation Satellite System (GNSS) measurements and bathymetric campaigns. RGB and multispectral UAV data were processed in order to extract the coastline, the topography and the inclination of the beach and to estimate the evolution of the littoral zone of the area.