Sea level rise along the East Asia and Chinese coasts and its role on the morphodynamic response of the Yangtze River Estuary

Coastal phenomena at river estuary areas will be affected by global climate change conditions. This paper reports on analysis of the sea level rise (SLR) from the last 50 years of tide stations data along the East Asia and Chinese coasts and morphodynamic changes in the Yangtze River Estuary determined for four SLR rates. Long-term tide records of 58 stations from the Permanent Service for Mean Sea Level (PSMSL) database were analyzed to develop projected estimates of the SLR trends. The calculated average rate of SLR is 2.67 mm/yr along the East Asia coasts, and 2.89 mm/yr along the Chinese coasts, with a 5.44 mm/yr estimate at the Yangtze Estuary, which is nearly three times the global average. Including the joint effects of the SLR and coastal land subsidence, the relative SLR will range from 1.5 m to 2.7 m at the Yangtze Estuary by the end of this century. Under the conditions of dry season water discharge, numerical simulation results show that the flood and ebb velocities would decrease for the SLR greater than 0.18 m. The areas of influence will increase proportional to the scale of SLR, significantly changing deposition conditions in this river estuary. Simulation results indicate that more dramatic morphological changes occur in the estuary during the dry conditions as compared to wet conditions. During the wet seasons, significant topography changes occur only for the SLR greater than 0.59 m, with an associated increase in the current velocities outside the river mouth. This may induce severe beach erosion problems, especially along the northern coasts of the Yangtze Estuary.