Characteristics of cross–channel momentum balance at Yeomha Channel, Gyeonggi bay, South Korea

Gyeonggi Bay, located in the middle of the West Sea of South Korea, is part of the Han River Mouth and exhibits unique and complex seawater flow characteristics. The high tidal difference causes strong tidal currents, which is related to the development of a wide tidal flat. Since tidal currents are guided by several major channels (e.g., Yeomha Channel) in Gyeonggi Bay, this study conducted a sectional field measurement in order to anlyse the momentum balance at Yeomha Channel. To understand the momentum balance at Yeomha Channel, the study derived horizontal friction coefficient (13.8m²/s) from the Smagorinsky method and vertical friction coefficient from Pacanowski method using scale analysis at each observation line. The analysis showed that the momentum was mainly balanced between advection acceleration term and friction term with spatio-temporally different characteristics. Particularly, at the entry of Yeomha Channel (Sound End of Choji Bridge, Line 1) where the width and water depth of the channel are drastically reduced, the magnitude of horizontal friction term was strong due to the tide wave. And near Incheon Harbor (South End of Yeongjong Bridge, Line 2), not only the horizontal friction, but also the vertical friction played an important role to be balanced by advective acceleration.