Water quality modeling for the water quality conservation of estuary reservoir in Korea

Hydrologic simulation program-fotran and Environmental fluid dynamics code model were applied for the Hwaseong Reservoir to evaluate water quality improvement by watershed management measures. The models were calibrated against the field measurements of streamflow, BOD5, COD, T-N, T-P, Chlorophyll-a at each observing point (six watershed and nine reservoir observed stations) from 2009 to 2010. The simulated results satisfactorily predicted the seasonal pattern of the observed ones and were within the reasonable range. The four scenarios for water quality improvement were applied to main tributary streams considering previous research reports and the Reservoir entrance from the inflow streams. The results demonstrate that the expansion and upgrade of wastewater treatment plant and pond/wetland construction would be great effective management measures. In order to achieve the target water quality and success the polder project, the measures that can control both point source and nonpoint source pollutants can be a key factor. However, for the stable water quality conservation, it is important to maintain the water quality efficiency rate of the pond/wetland system. Thus, the treatment rate of the water quality by the pond/wetland system should be monitored and maintained consistently.