Abstract
A field measurement was conducted on Banzu intertidal sand-flat in Tokyo Bay, Japan, for 16 days in February 2000, aimed at investigating hydrodynamics, sediment suspension and short-term morphodynamic responses on the flat. The results of a 16-day measurement and a 6-year survey of bed levels have demonstrated that the Banzu flat has a morphological process consisting of a long-term gradual accretion, short-term episodic erosions and the following accumulations. The topography of the tidal flat fluctuated by approximately 8cm during the 16 days with the significant wave height in excess of 0.8m, which was relatively large for shallow waters in Tokyo Bay, although the long-term accumulation rate is estimated to be only about 3.8cm/y. Episodic erosions appeared to occur with high turbidity, which was caused by the combination of relatively high wave and strong tidal current accelerated by the wind between the high water and the mean water during the ebb tide. The tide fluctuation, as well as wave action and wind forcing, plays a key role in hydrodynamics and associated morphological process on the tidal flat.
