Mud siltation in the north harbour of Incheon, Korea

초록

The development of North Harbour was initiated at a macro-tidal flat within the Harbour Complex of Incheon, Korea in 1997 (Fig. 1). To maintain the design depth of -14m below LLW (Low LowWater) from the tidal flat of 2m above LLW, dredging operation has been repeated over the last 13 years within the unbalanced (disequilibrium) North Harbour. In efforts to reduce the siltation within the harbour, this paper attempts to estimate siltation rate and then determine dominant mechanisms for the siltation within the North Harbour. The siltation rate was estimated and then confirmed by the following two independent methods: comparison of available hydrographic sheets and radioisotope analysis of gravity cores. The sedimentation rate varied from 10cm/yr in the far end of the harbour to about 100cm/yr at the entrance (Fig. 2). In order to determine dominant mechanisms for siltation, two ADCPs and two CTDs were deployed at the entrance and the far end of the harbour over a month, and examined flow mechanisms for a harbour basin (Fig. 3). Moreover, the EFDC model simulation indicated that the eddy forms during the flood of spring tide and it appears to be responsible for the high siltation at the harbour entrance (Fig. 4).