Automatic extraction of highly risky coastal retreat zones using Google Earth Engine (GEE)

Coastal areas have been one of the favorite places of humanity throughout the ages and have been used for settlement, transportation, recreation, defense and trade as areas that attract human beings. In addition to creating habitats for animals and plants, these regions provide vacation and resting opportunities due to the mild and soft effect of their microclimate climate. The attractiveness of coastal regions has caused people to turn to these areas for various reasons, and as a result of this orientation, the facilities and living spaces built in these regions have affected the change of coastal regions. For this reason, it has been an important issue to determine the position of the coastline and to determine the changes it has undergone over time. In this study, an approach that can automatically detect the shoreline over Landsat data and reveal metric changes for different temporal periods with the help of various spatial query and image processing algorithms on the GEE platform, which is a geographical data processing platform that provides free access to many remotely sensed datasets to users, is proposed. With the proposed approach, coastline changes for different temporal periods between 1985 and 2021 are coded in the GEE platform using python software language. The results obtained revealed ten important regions with maximum coastal change, three of which were erosion and seven areas of accumulation, in the Southern Black Sea coastal region. It has been determined that while the maximum change amount is approximately -634 m in erosion zones, it reaches up to 1204 m in agglomeration zones. In this study, it is expected that the coastal change will be determined quickly and will contribute to the decision makers in matters related to coastal management and planning.