Author(s): Nak Yong Choi; Byung Il Yoon; Jong Wook Kim; Jin Il Song; Seung-Buhm Woo
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Keywords: Gyeonggi Bay Seokmo Channel; Residual current; Richardson number
Abstract: The Han River estuary of Gyeonggi Bay, which is located in the mid-Yellow Sea off the coast of South Korea, exhibits unique and complex tidal circulation characteristics due to its large tidal range, very strong tidal currents and extensively developed tidal flat. This study analyzed the cross-sectional variations in the residual current and the strengths of stratification by observing the cross-sectional velocity and the salinity during spring tide and neap tide, respectively, for continuous 13-hour periods at2 observation lines at the northern and southern end of Seokmo Channel, which is located west of Ganghwado. The residual current component was obtained by removing the M 2 and M 4 tidal components that were extracted using the least squares method on the 13-hour velocity component. The cross-section of the average residual velocity at the northern end of Seokmo Channel exhibited a seaward current component of 0.05 m/s during neap tide and 0.21 m/s during spring tide. From the observation line at the southern end, the seaward current was 0.14 m/s during the neap tide and 0.17 m/s during the spring tide, but the landward residual current was observed at the channel's bottom layer, clearly showing a 2-layer tidal circulation between the surface and bottom layers. The unique characteristic of the residual current observed at observation line was that the location of the landward residual current flows at bottom layer appears to be different in the eastern and western sides of the channel depending on spring and neap tidal cycle. The variation in the location of the appearing landward residual current according to the changes in spring and neap tidal cycle and its correlation with the stratification were analyzed using the Richardson number. At the northern and southern end of Seokmo Channel, landward residual current appears in the location that Richardson number is large. These results suggest that the cross-sectional residual current pattern at Seokmo Channel changes depending on freshwater and topographical influences and is sensitive to tidal changes, such as changes in the spring and neap tidal cycle.
Year: 2012