The Along-channel Salinity Distribution and its Response to River Discharge in Tidally-dominated Han River Estuary, South Korea

Abstract

The Han River Estuary (HRE), located on the west coast of South Korea, is well known for its macro tidal characteristics with a tidal range more than 8.5 m. This estuary has a distinctive salinity distribution because its system consists of 3 main channels and 3 rivers, through which major tidal flow and river discharge meet each other. To determine the effect of change in external forcing (e.g., river discharge and tidal variation) on the salinity, a numerical model is established and verified with observation. Based on previous observation, the main channel of HRE shows well- and/or partially-mixed estuary during spring and neap periods, respectively. The vertical stratification during the neap period is stronger than that during the spring due to decreasing turbulent mixing. The numerical results show that the salinity distribution during high river flow condition can be temporally and spatially characterized by river discharge. The asymmetries of the salinity distribution response to increasing and decreasing river discharge are indicated in this estuary. During high river flow conditions, the front of Incheon Harbor is within the region of the freshwater influence.