Shen, Q.; Gu, F.; Qi, D., and Huang, W., 2014. Numerical study on the flow and sediment variation affected by the sea-level rise in the north passage of the Yangtze estuary.

A three-dimensional, sigma coordinate coastal ocean model, based on unstructured C-grid and semi-implicit finite volume method, is built to study the flow and sediment variation affected by the sea-level rise (SLR) at the north passage of the Yangtze estuary. Firstly, the details of the numerical method used in this model are introduced, including the layout of model variables, the discretization of the governing equations and the semi-implicit method, etc. Then, two test cases are employed to verify the proposal model, including an idealized test case as well as a simulation of the tidal flow and mass transport at the north passage of the Yangtze Estuary. Finally, based on the verified model, a numerical study on the flow and sediment variation affected by the SLR at the north passage of the Yangtze estuary is carried out. The result shows that near the outlet of the Yangtze Estuary deep water channel, the residual currents at the surface and bottom are in opposite directions with seaward flow at the surface and landward near the bottom. The intruding saltwater, together with the stratification near the outlet of the Yangtze Estuary deep water channel, is strengthened by the SLR of 50cm and consequently increases the flow exchange. With the SLR of 50cm. the largest increments of salinity as well as the sediment concentration appears in the upper part of the Yangtze Estuary deep water channel ranging from CS6S to CSWS. It increases the vertical stratification and strengthens landward residual current near the bottom while the seaward residual current is increased at the surface. The high concentration zone of Yangtze Estuary deep water channel moves upstream due to the SLR of 50cm which consequently changes the distribution of channel siltation.