An experimental study on erodibility of intertidal sediments in the Yellow River delta

The erodibility of intertidal sediments is an important factor affecting coastal erosion. In July and October 2008, in situ measurement of erodibility of the surficial sediment were conducted using a recirculating flume at 20 tidal flat experiment sites along the seashore of the Yellow River delta. At the same time, the characteristics of sand ripples and biogenic features on the tidal flat were observed and the physical-mechanical sediment properties such as bulk density, water content, grain size distribution, plasticity, penetration resistance, shear strength and compressibility, were measured. By field measurement, it is obtained that the critical erosion shear stress of the surficial sediment on the tidal flat varies between 0.088 Pa and 0.254 Pa. The factors influencing sediment erodibility are complicated because of physical and biological reworking after the sediment deposited. There's a positive correlation between shear strength and critical erosion shear stress. The burrowing crabs' activities changed the sediment microtopography and made the sediment have greater roughness, and that is one possible reason for the higher erodibility. The formation of scour pits on the tidal flat correlates with the heterogeneous erodibility of the surficial sediment.