Physical study of the response of tidal flat development to the reduction in the input of Yellow River sediment into the sea

Feng Yi ^1,2*

• ¹ Institute of Coastal Research, Ludong University, Yantai, China
• ² State Key Laboratory of Coastal and Offshore Engineering, Faculty of Infrastructure Engineering, Dalian University of Technology (DUT), Dalian, Liaoning Province, China

Over the past three decades, 16% of the world's tidal flats have been lost. To investigate the response of tidal flat development to the reduced input of Yellow River sediment, natural silt from the Yellow River delta tidal flat was used to construct a novelty physical model experiment. The reduction in sediment input was simulated by decreasing the offshore sediment concentration. Additionally, an Argus system was incorporated into the wave basin to capture the scene for the first time. This study examines the variation of suspended sediment concentration (SSC) in the subtidal zone, the mechanisms driving sand wave movement and development, the evolution of tidal flat microtopography, and the spatial distribution of erosion and accretion. The results indicate that 94% of the suspended sediment settles during its transport from offshore to tidal flats. SSC in the subtidal zone gradually increased during the flood tide and decreased during the ebb tide. As SSC gradually decreased, the intertidal zone developed comb-shaped flow marks along the vertical shoreline, while the subtidal zone became dominated by sand waves. For a given SSC, the sand wave statistical characteristics and variation patterns differ across profiles. For varying SSC, the development of sand waves in a given profile shows distinct differences. This study examines the morphological evolution of tidal flats in the Yellow River Delta (YRD) as SSC decreases. The findings suggest that a further reduction in SSC may increase the risk of erosion in the YRD in the future.