抄録
Long-duration observations of tidal current and stratification have been conducted in the Ohta flood-way. The data demonstrate a semi-diurnal stratification cycle driven by tidal straining of freshwater-induced horizontal density gradient, i. e., the stratification during the ebb is stronger than that during the flood. As a result, the data of current profilers show that the velocity distribution during the ebb deviates from logarithmic law. The nonlinearity of tidal wave and tidal straining mainly bring about the asymmetry of tidal current and bottom shear-stress. At 2.8 km upstream from the mouth, the maximum bottom shear-stress during the flood is twice as large as that during the ebb. A numerical model incorporating a level 2.5 turbulence closure scheme reproduces the main feautures of the observations and is used to investigate the behaviour of the current and bottom shear-stress.
