Observation of Sediment Plume Dispersion around Ieodo Ocean Research Station in the East China Sea Using Satellites and UAVs

Sediment plumes in marine environments significantly impact ecosystems by increasing turbidity, depleting bottom-water oxygen, and transporting pollutants. In general, there is a special plume, called Ieodo plume, which is a characteristic bent plume originating from the Ieodo seamount in the northern East China Sea. While satellite-based remote sensing is commonly used to study such phenomena, its spatiotemporal resolution is often insufficient for monitoring rapidly changing marine dynamics. Thus, it is still challenging to understand their specific behavior, dispersion patterns, and range of influence. This study investigates the behavior and dispersion of the Ieodo plume using integrated UAV (Unmanned Aerial Vehicle) and satellite observations. Continuous UAV-based hovering observations were conducted on the Ieodo Ocean Research Station, adjacent to the plume, utilizing optical and multispectral sensors. Optical sensors were employed to monitor flow at the plume's source, while surface currents derived from Optical Flow algorithm were combined with tide and wind data from real-time in situ observations at the research station to estimate plume dispersion range theoretically, using equations derived from plume dynamics. These theoretical predictions were validated against Sentinel-2 optical satellite imagery. Multispectral sensors were used to derive suspended sediment concentration (SSC) information within the plume based on remote sensing reflectance (R_rs). This study provides a comprehensive understanding of the initial characteristics and dispersion of the Ieodo plume based on theoretical and observational analysis. These results are expected to be applicable to predict plume dispersion caused by riverine outflows, seabed resource extraction, and dredging operations, thereby contributing to better management of such marine phenomena.