Impact of Shoreline Ecological Restoration on Suspended Sediment Concentration in Shanghai Coastal Waters

Abstract. The coastal waters of Shanghai are characterized by high turbidity due to sediment input from the Yangtze River and strong tidal forces. Rapid urbanization has led to shoreline hardening, altering hydrodynamics and sediment transport, resulting in ecological degradation. Although ecological restoration measures have been initiated, their broad impacts on suspended sediment concentration (SSC) remain unclear. In this study, a model for retrieving SSC in Shanghai's nearshore waters was developed using data from the Gaofen-1/Gaofen-2 satellites and the Quasi-Analytical Algorithm (QAA). The exponential model (SSC = 21.959·exp(0.9335·bbp)(R² = 0.7305)) . Applying this model to time-series data from 2020 to 2024 revealed that SSC values at traditional hardened shoreline Area were higher and more variable (summer mean = 145 mg/L, standard deviation = 96 mg/L), whereas natural reference areas maintained lower SSC levels (mean = 45 mg/L, standard deviation = 11 mg/L). SSC in Lingang ecological restoration area showed intermediate values (87 mg/L) with reduced variability. During the construction phase (2022– 2023), SSC temporarily increased but significantly decreased after completion, approaching natural levels again. These results indicate that ecological restoration can effectively stabilize sediment conditions, providing scientific support for coastal management. Keywords: Suspended Sediment Concentration (SSC),Shoreline Ecological Restoration,Shanghai Coastal Waters, Quasi-Analytical Algorithm (QAA),Remote Sensing Monitoring.