Scour characteristics and dynamic mechanisms of the breakwater head in the abandoned Yellow River Delta on the northern Jiangsu coast, China

Abstract

Breakwater scour seriously affects the safety and stability of breakwater foundation. Previous research has primarily focused on breakwater scour of sandy coasts, and to date, limited studies exist on silty–muddy coasts. This study analyzed the causes of scour around the breakwater head in Binhai Harbor, Jiangsu Province from the perspective of hydrodynamic changes and sediments based on years of field observation data and a two-dimensional tidal current numerical model. The observation results showed that four years after breakwater construction, a scour hole with a scour depth over 20 m formed in the northeast of the breakwater head. The development of the scour experienced a process of sudden acceleration, followed by slowing. After the construction of the breakwater, the tidal flow velocity near the breakwater head exceeded the critical motion velocity of the muddy clay layer, which was the main factor for the formation of the scour hole. Our findings indicate that when the scour tended to an equilibrium, the scouring area expanded to the northern and southern sides. This research provides a reference for studying morphodynamic change processes caused by the construction of marine structures on silty–muddy coasts.