This study examined the effects of freshwater discharge by artificial dikes from the Kanwol and Bunam lakes on the dynamics in the Chunsu Bay, Yellow Sea, Korea, during the summer season based on three-dimensional numerical modeling experiments. Model performances were evaluated in terms of skill scores for tidal elevation, velocity, temperature, and salinity and these scores mostly exceeded 90 %. The variability in residual currents before and after the freshwater discharge was examined. The large amount of lake water discharge through artificial dikes may result in a dramatically changed density field in the Chunsu Bay, leading to an estuarine circulation system. The density-driven current formed as a result of the freshwater inflow through the artificial dikes (Kanwol/Bunam) caused a partial change in the tidal circulation and a change in the scale and location of paired residual eddies. The stratification formed by strengthened static stability following the freshwater discharge led to a dramatic increase in the Richardson number and lasted for a few weeks. The strong stratification suppressed the vertical flux and inhibited surface aerated water mixing with bottom water. This phenomenon would have direct and indirect impacts on the marine environment such as hypoxia/anoxia formation at the bottom.

Abstract
1. Introduction
2. Data and Method
    2.1 Observations of Hydrodynamic and HydrographicConditions in the CSB, 2010
    2.2 Lake Water Discharge Conditions in the CSB, 2010
    2.3 Model Specification and Run Cases
    2.4 Model Performance and Validation
3. Results
    3.1 Observation results
    3.2 Model Performance and Validation
    3.3 Simulation of Current Field
    3.4 Simulation of Salinity Field
    3.5 Stratification Strength
4. Discussion
    4.1 Circulation System
    4.2 Stratification formation and maintenance
    4.3 Environmental implications of the artificial dikes
5. Conclusions
References

• Kwang-Young Jeong(Ocean Research Division, Korea Hydrographic and Oceanographic Agency)
• Young Jae Ro(Department of Ocean Environmental Science, Chungnam National University) Corresponding Author
• Tae Soon Kang(Department of Coastal Management, GeoSystem Research Corporation)
• Yang Ho Choi(Fisheries Resources and Environment Research Division, South Sea Fisheries Research Institute)
• Changsin Kim(Fisheries Resources Management Division, National Institute of Fisheries Science)
• Baek Jin Kim(Department of Ocean Environmental Science, Chungnam National University)