Deriving Accurate Intertidal Topography for Sandy Beaches Using ICESat-2 Data and Sentinel-2 Imagery

Abstract

Sandy beaches are one of the most dominant coastal types across the world, which can protect the coast and provide tourism. The intertidal zone is inundated with dynamic tides, making it challenging to obtain the intertidal topography near sandy beaches due to their narrow widths, particularly in sparsely populated areas with rare in situ measurements. Recently, the Ice, Cloud, and land Elevation Satellite 2 (ICESat-2) photon-counting lidar offers unprecedented finer observations in elevation in coastal zones. In this study, we aimed to explore the capacity of combining ICESat-2 altimeter data and Sentinel-2 imagery in deriving the intertidal topography for sandy beaches. Our results indicate that the satellite-derived sandy beach intertidal topography (with a resolution of ~3 m) in Texas, USA exhibits a good accuracy of 0.35 m compared with a local high-resolution digital elevation model dataset. Moreover, we generated the coastal lowland map from the beach topography and validated the lowland results using high-resolution data. We highlighted that our proposed method for inverting the topography of sandy beaches are based on globally accessible satellite data (i.e., without in situ data), demonstrating the potential for applications in various coastal zones around the world.