The spatio-temporal distribution and transport of suspended sediment in Laizhou Bay: Insights from hydrological and sedimentological investigations

Abstract

Suspended sediment transport and deposition are crucial physical processes controlling the geomorphological evolution of estuaries and bays. Specially, under the context of worldwide coastal erosion, knowledge of the spatio-temporal distribution of suspended sediment concentration (SSC) and its associated sediment load have become increasingly important for bay management. However, our understanding of the mechanisms of suspended sediment dynamics continues to be hampered by the lack of high-resolution observations. Here, we present a study of the transport mechanisms and controlling factors of suspended sediment over Laizhou Bay. For this, we conducted continuous measurements of SSC, salinity, temperature, and flow velocity at nine stations throughout Laizhou Bay for one 25-h period during each of the spring and moderate tides. Based on these data, residual current, gradient Richardson numbers, and suspended sediment flux were calculated. Our results indicate that a strong current field occurs near the Yellow River mouth, corresponding to the zone with high SSC. The overall diffusion characteristics of suspended sediment are controlled by the tidal current field. Furthermore, our findings suggest that different degrees of stratification occur in the water column, which inhibit the effective vertical diffusion of suspended sediment; Higher water temperature was the main cause of stronger water column stratification of spring tide than moderate tide. Finally, our results reveal that the type of seabed sediment is an important factor controlling SSC by influencing resuspension flux. We conclude that the primary mechanisms controlling suspended sediment transport in Laizhou Bay are advection and tidal pumping, especially advection. Our research provides both a foundational reference for the sediment source-to-sink process from the Yellow River to the sea, as well as guideline implications for coastal engineering construction and channel dredging.

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

“…Furthermore, during the flying-over of the satellite on 12 October 2022, the wind speed in most of Laizhou Bay was less than 5 m/s, while on 12 November 2021, the wind speed was higher than 6 m/s (Figure 8). Previous research findings have consistently demonstrated that the dispersion patterns of suspended sediments are influenced by the dynamics of tidal currents [37,38]. Variations in suspended sediment concentrations are primarily induced by seasonal oscillations in sea surface elevation and wind-induced waves [39], with tidal level fluctuations regarded as short-term variations in sea surface elevation.…”

Numerical study of the water-sediment regulation scheme (WSRS) impact on suspended sediment transport in the Yellow River Estuary

“…Tides can change the flow cycle mode in the YRE, resulting in different sediment transport patterns (Shan et al, 2004). The diffusion characteristics of suspended sediment in the YRE and its offshore region are controlled by the tidal current field (Xie et al, 2022). Sediment in the no-tide scenario mainly accumulates at the river mouth and diffuses toward the northwest with a small spread range (Figure 11D), then it flows along the YRE coast with the tidal current (Figure 11A).…”