Monitoring Suspended Sediment Concentration in the Yellow River Estuary and Its Vicinity Waters on the Basis of SDGSAT-1 Multispectral Imager

Abstract

Suspended sediments have profound impacts on marine primary productivity and the ecological environment. The Yellow River estuary and its vicinity waters, with a high dynamic range of suspended sediment concentration (SSC), have important eco-environmental functions for the sustainable development in this region. The multispectral imager (MI) on board China’s first Sustainable Development Goals Science Satellite 1 (SDGSAT-1) features seven high-resolution bands (10 m). This study employs multispectral imagery obtained from SDGSAT-1 with single-band and band-ratio models to monitor the SSC in the Yellow River estuary and its vicinity waters. The results show that SDGSAT-1 images can be used to estimate the SSC in the Yellow River estuary and its vicinity waters. The overall pattern of the SSC exhibits a notable pattern of higher concentrations in nearshore areas and lower concentrations in offshore areas, and the retrieved SSC can attain values surpassing 1000 mg/L in nearshore areas. The R2 values of both the single-band and the band-ratio models for SSC inversion exceed 0.7. The single-band model R(854) demonstrates superior performance, achieving the highest R2 value of 0.93 and the lowest mean absolute percentage error (MAPE) of 44.04%. The single-band model based on SDGSAT-1 R(854) tends to outperform the band-ratio models for waters with algal blooms, which may be used for inversions of SSC and/or suspended particulate matter (SPM) in the waters full of algal blooms and suspended sediments. The monitoring results by SDGSAT-1 suggest that the complex SSC distributions in the Yellow River estuary and its vicinity waters were highly impacted by the river sediments discharge, tide, currents and wind-induced waves.