The construction of wave dissipating platform would cause the sediment transport in the surrounding waters, changing the erosion and silting situation in the seabed, which may even lead to the abandonment of the original dock. In this paper, a 2D hydrodynamic and sediment transport model is established for Shengsi islands, Zhoushan and the surrounding area by using MIKE21. The model has well been validated through observation data of tidal level, flow velocity and direction. The influence of dissipating platform construction on the erosion and deposition of surrounding water is analyzed. The results show that the maximum diffusion envelope of suspended sediment (concentration higher than 0.02 kg/m3) in Huangsha village, Bianjiaoao and Huicheng village are 20,947.02, 19,799.04 and 5,311.35 m2 respectively. The project has little impact on the surrounding water quality environment.
The coastal construction has created enormous social and economic benefits, but the construction project has caused sediment transport in the surrounding waters, causing erosion and siltation changes which may even cause the original dock abandoned (Tsoukala et al., 2015; Plomaritis and Collins., 2013; Song et al., 2017; Zhang et al., 2005). Meanwhile, it exerts negative effects on marine ecological environment, arousing wide public concern of scholars (Sravanthi N, 2015; Yao et al., 2018; Gu et al., 2012; Tian and Xu, 2015).The suspended sediment produced during the construction process will form water masses with high suspended matter content within a certain range, weakening or even blocking the light transmission capacity of the water body, affecting the photosynthesis of phytoplankton. The reduction in the number of phytoplankton will cause a corresponding reduction of zooplankton. In addition, suspended sediment will attach to the surface of aquatic animals, interfere with their normal physiological functions, and more seriously enter the digestive system, causing death (Huang et al., 2019). Zhang (2015) used the ECOMSED model to simulate the terminal project of Shandong LNG project. The research obtained the maximum spreading range of suspended sediment produced by excavation of base trenches, stone dumping and dredging works during the spring and neap tides, and analyzed the impact of the project on marine life. Yan (2019) established a two-dimensional model by using MIKE21 FM, simulating the envelope area of the suspended sediment caused by the 10 kv submarine cable laying at Lvhua Island-Huaniao Island. The results show that the construction period has a greater impact on the marine ecological environment, and the service period has basically no impact on the marine ecology. In order to serve human life and protect the environment, numerical simulation has been widely used in engineering construction (Vu, Nguyen and Nguyen.,2020; Agrawal et al.,2019).