Variation of Residual Currents in Kyunggi Bay of Korea

Chang S. Kim*, Hak Soo Lim, Young-Ho Kim and Kyung Tae Jung

Coastal Engineering Division, Korea Ocean R&D Institute
454 Haean-Ro Ansan 426-744 South Korea
Email: surfkim@kordi.re.kr FAX: +82-31-400-6340


Abstract

The residual current, defined as the flow averaged over the tidal cycle, plays an important role in estuarine and coastal processes. The macro-tidal river environment, the Great Han Estuary has three main channels through which the riverine sediment load is discharged into the Kyunggi Bay. It is generally accepted that the magnitude and direction of the residual current at each channel would determine the dispersal and deposition processes in the macro-tidal flats of varying composition of grain size. However up until now, it is far from clear whether the residual flows in this area are flood- dominant pr ebb-dominant. There are numerous factors for the residual flows to be created and modified. In estuarine and coastal environment such as the Kyunggi Bay, the shallow water depth, interaction among multiple tidal constituents, river discharge and surface wind and wave effects would be the factors among others.

The present study investigates the characteristics and variability of the residual flows at major points of the channels. We use two types of flow data; flow data measured in the field and the data simulated using the ROMS with dry and wetting nearshore module. One-month long current data have been used to estimate the residual currents using three methods; Time average over varying periods, digital filtering of subtidal components and the tidal harmonic method.

In this study, comparison of spatially and temporally varying residual currents estimated by different methods is presented to elucidate a prospecting mechanism responsible to the tidal flat dynamics in Kyunggi Bay, Korea.