Impacts of coastal reclamation on tidal and sediment dynamics in the Rui’an coast of China

Coastal reclamation projects have been extensively constructed along the coastline of the East China Sea over the past decades. To investigate the impact of reclamations on the Rui’an coastal zone, regional tidal and sediment dynamics were studied by combining field data and numerical modeling. Field data of tidal elevation and currents, suspended sediment concentration (SSC), and bottom erosion were obtained during both spring and neap tides from 2014 to 2019. Data analysis suggested that the reclamation and construction of the dike reduced the currents in the tidal flat and subsequently reduced the SSC values. The sediment was mainly deposited in the tidal flat after construction. The largest annual deposition rate was approximately 1 m, occurring in the southern part near the dike, while the deposition rate was only 0.08 m/a in the middle part of the tidal flat. In addition, the results of the numerical experiment proved that the reclamation and dike construction contributed to the variations in currents and SSC, thus altering the deposition in the tidal flat. It is suggested that the construction of coastal works and social facilities in macro-turbid coastal zones, such as the Rui’an coast, require the evaluation of possible impact on sediment dynamics.