교각건설로 인한 나로도 협수로 부근해역에서의 조류변화 수치모형실험

The Numerical Model Experiments on the Tidal Current Variations Due to the Bridge Piers Construction near the Straits of Narodo Islands

The field observation and numerical experiments with a two-dimensional depth-integrated model have been undertaken in order to investigate some impacts on the flow structure resulting from the construction of a bridge connecting Kohung Peninsula and the Narodo Islands on the southern coast of Korea. Tidal currents passing through the straits between the Narodo Islands showed that, although the phase lagged one hour behind that passing through the strait between Kohung Peninsula and Naenarodo Island, it still kept strong flows of more than 80cm/sec near the bottom. The horizontal distributions of seawater temperature and salinity within the study area seemed to be higher southward but uniform vertically. The results of the drogue experiments in the straits between the Narodo Islands showed that the drogues moved northward of Sayangdo in the early part of the flood tide, but southward in the late part of the flood tide and finally stopped when they reached a mile from the east coast of Surakdo. On the other hand, the numerical computation showed that the flow structures after construction of bridge piers were basically in line with those before construction of bridge piers except for the slight variations of velocities in the vicinity of the bridge piers. A large scale clockwise circulation has been confirmed in the south area of Namsungri of Kohung Peninsula from the computational results of tide-induced residual currents. Referring to these computational results, the impact category on the flow structures due to the bridge piers construction has been estimated to be within around 2km. The results were in good agreement with the field observations.