ACCURACY OF SATELLITE-DERIVED WATERLINE EXTRACTION METHODS ON SANDY BEACHES

Satellite-based observations now play a key role in monitoring the morphological evolution of coasts, enabling the extraction of diverse change indicators. While satellite-based methods offer significant advantages for large-scale coastal monitoring, there is a limited body of research that assesses their robustness. Each step in the waterline extraction process introduces potential sources of error, and the diverse characteristics of coastlines, including their nature, tidal range, and wave climate, pose additional challenges that can significantly affect the accuracy of the detection. In this study, we evaluate the performance of a standardized satellite-derived waterline extraction method by validating its results using ground truth data from a dozen of sites around the world. We investigate the impact of pixel indexing on the performances of the process. Additionally, we establish links between beach characteristics and the accuracy of waterline detection.