Song, H.-Y.; Lee, S.-W., and Yoon, J.-J., 2023. Effect of freshwater discharge on the water quality in Cheonsu Bay, West Coast of Korea. In: Lee, J.L.; Lee, H.; Min, B.I.; Chang, J.-I.; Cho, G.T.; Yoon, J.-S., and Lee, J. (eds.), Multidisciplinary Approaches to Coastal and Marine Management. Journal of Coastal Research, Special Issue No.116, pp. 56-60. Charlotte (North Carolina), ISSN 0749-0208.
The purpose of this study was to investigate the changes in, and effects on, the water quality off the coast of Cheonsu Bay of the West Coast of Korea, when freshwater is discharged from artificial lakes (Bunam Lake and Ganwol Lake). Samples were collected during the summer when a large amount of freshwater inflow occurred. Evaluation of the water quality status of the two lakes revealed that the Tropic State Index (TSIKO) value at all sites was 70 or higher, indicating a hypertrophic state. The correlation between water quality factors was reviewed to examine the changes in water quality due to freshwater inflow. Salinity was significantly and positively correlated with DO saturation and transparency. DIN, DIP, SiO2-Si, and COD showed significant negative correlations with salinity. It was confirmed that the water quality changed owing to the inflow of freshwater. In the case of Chl-a, there was a significantly positive correlation with nitrogenous nutrients. As a result of evaluating the water quality and nutritional status of the water due to freshwater inflow, we found that the Water Quality Index (WQI) was grade II–V before discharge but deteriorated to grade V (very bad) at all sites when freshwater is discharged. In addition, the nutritional status index TRIX was normal with grades II to III before freshwater discharge, but all sites deteriorated to a poor state of grade IV during freshwater discharge.