Satellite remote sensing applications in estuarine morphodynamic studies: a comprehensive overview

Understanding estuarine morphodynamics is essential for resource development, ecological protection, and disaster prevention. However, these efforts are often hindered by limited field data. Satellite imagery provides a cost-effective, spatially explicit, and periodic method for monitoring estuarine areas, offering substantial advantages over traditional field surveys. This study reviews the application of satellite remote sensing data and image processing techniques for analyzing estuarine morphodynamics, including key components such as coastlines, suspended sediments, bathymetry, spatial patterns of channels, tidal flats, sandbars, sand islands, and tidal wetland vegetation. The results indicate that systematic detection of estuarine morphodynamic evolution using remote sensing has been limited. Major challenges include the variability in weather conditions, background settings, and tidal dynamics across different temporal scales of satellite imagery. Additionally, image processing techniques effective for single images may not perform as well with time-series images. To address these challenges, several solutions are proposed, including the selective use of image sources, determination of tidal-level positions, and the application of machine learning and deep learning models. This review is conducive to deepen the scientific understanding of estuarine evolutionary laws and driving mechanisms through satellite remote sensing techniques across multiple timescales, and minimize the need for extensive field measurements.