A modeling study on residence time in the Youngsan River estuary, Korea

The study area (Youngsan River estuary, YRE) has been changed into a semi-enclosed bay system since the YRE dam was constructed in 1981. In this paper, the water residence time was calculated in the YRE by coupling the Lagrangian transport and the hydrodynamic models. We accounted for the effects of the freshwater discharge from the YRE dam for the flood, normal and dry season using by the MOHID model. The freshwater discharge from the YRE dam is determined by estuarine circulation. Depending on the characteristics of the freshwater discharge from the YRE dam, the average residence time during the dry season is longer than that of the flood season. The most vulnerable area of water pollution in the YRE can be located in northern-eastern area of the YRE. It is necessary to put more efforts into improving the water quality by conducting continuous monitoring and sound management particularly in this area.