Wave effects on sediment transport on the tidal flat, Gangwha, Korea

초록

Tidal flats of Incheon, Korea are located off the coast of the Han River mouth. The extensive macrotidal mud flats, for which tidal range exceeds 9 m, are unique in that freshwater discharge during the summer wet season influences the region, while strong waves dominate resuspension and transport processes during winter. A field campaign initiated to better understand imparting influences of these processes and a benthic pod was deployed in a tidal channel in Southern Gangwha tidal flats during November, 2006 and Septermber-October, 2007. Instrumentation on the pod includes one Acoustic Doppler Velocimeter, one Acoustic Backscatter System, and two Optical Backscatter Sensors. Sediment suspension mainly occurred during the accelerating phase of flood and ebb. On the other hand, deposition occurred during the slack after flood when waves were relatively weak. When waves were stronger, wave-induced shear appeared to support sediment suspension even during the slack after the flood. This phenomenon has an important ramification on sediment budget on the upper reach of tidal flat.