High-Resolution Satellite Mapping Sheds Light on Coastal Sediment Dynamics

Coastal landscapes like beaches, tidal wetlands, and mudflats provide critical benefits: they support biodiversity, store blue carbon, and act as natural barriers against storm surges. These environments rely on a continuous supply of sediment from sources such as rivers and marine processes, including coastal erosion and biological production, to maintain their stability, especially as they face threats like sea level rise. While sediment from rivers is relatively well studied, sediment originating from marine sources remains much harder to monitor, largely due to the dynamic and complex nature of coastal waters. Satellite ocean color monitoring products exist, but their coarse resolution (around 1 km) is often too low to capture the fine-scale sediment patterns critical for understanding and managing coastal ecosystems. Improving high spatial-resolution monitoring of suspended sediment concentration (SSC) is therefore essential for advancing our understanding of sediment movement, coastal resilience, and ecosystem health.

To tackle this challenge, a new publication authored by NE CASC researchers Wenxiu Teng, Brian Yellen, and Jon Woodruff develops a novel approach for mapping SSC at high resolution in global coastal waters, even in areas where suspended particles vary widely in composition. Their work appears in the journal Remote Sensing of Environment. The team has created a particle composition-adaptive algorithm that uses satellite data to classify waters into organic-rich, mineral-rich, or extremely mineral-rich types. Each type is then assigned a specific SSC retrieval method based on the most suitable spectral bands. Team members built and validated this model using over 800 paired in situ measurements of reflectance and SSC from 12 different coastal sites worldwide. Applying the algorithm to 40 years of Landsat data via Google Earth Engine, the researchers produced fine-scale maps that capture seasonal and long-term changes in coastal sediment dynamics. Validation against both in situ SSC and turbidity data shows that the new method improves accuracy compared to eight existing algorithms. This work provides a new way to better monitor and understand coastal sediment supply at high spatial resolution globally.

To make this data broadly accessible, the team also created an interactive web tool that allows users to visualize sediment patterns and download time-series sediment data from any coastal location on Earth, spanning the past four decades. This new capability opens the door to global-scale assessments of marine sediment delivery and an enhanced understanding of its role in supporting vulnerable coastal ecosystems.