Correlation between freshwater discharge and salinity intrusion in the Han River Estuary, South Korea

Abstract

Yoon, B.I. and Woo, S.B., 2013. Correlation between freshwater discharge and salinity intrusion in Han River Estuary, South Korea In: Conley, D.C., Masselink, G., Russell, P.E. and O'Hare, T.J. (eds.)The salinity distributions of estuaries and tidal rivers exhibit unique characteristics due to the effects of various external forces, such as tides, freshwater discharge, wind, and topographic effects. The interpretation and understanding of the structure of salinity profiles in coastal and estuarine areas is necessary for addressing issues related to oceanography, water quality, ecology, and engineering. To identify the salinity distribution of Han River Estuary (HRE), South Korea the surface salinity of the southern and northern regions of Yeomha Channel were observed from May to June, 2007. Variations in the salinity were clearly correlated with long- and short-term tidal fluctuations. Furthermore, the salinity strongly decreased when additional freshwater was discharged relative to the dry period, and more than 25 days were required following a high-discharge period to restore the salinity to that of the normal flow conditions. The characteristics of the axial salinity distribution in the Yeomha Channel of the HRE were studied using data from the National Marine Monitoring Network of the National Fisheries Research and Development Institute, and the length of the salinity intrusion relative to the tidal range, the amount of freshwater discharge, and topographic effects were expressed using an empirical equation. A correlation between the saltwater intrusion limit at the HRE and the freshwater discharge rate was expressed using an empirical equation. Based on this simple analytical approach, we believe that the structural characteristics of the salinity distribution in estuaries and tidal rivers vary not only due to freshwater discharge and tidal mechanisms but also due to topographic effects.