COMPARISON OF VELOCITY PROFILES ASSOCIATED WITH TIDAL ACCELERATION AND DECELERATION OVER INTERTIDAL FLATS

Since the intertidal flats at Dafeng, Jiangsu Province are characterized by shallow water, strong tidal currents and waves, the whole depth of flow can be regarded as the boundary layer, i.e. the velocity profile is logarithmic structure. However, it may depart from the usual logarithmic form in an accelerating or deceleration tidal flow and will result in tremendous error if the logarithmic von Karmen-Prandtl equation is used to calculate the parameters. Current speeds and turbidities have been measured by using MIDAS-400 at various heights over the tidal flats. The u-lnz regression analysis and the internal consistency analysis were adopted and a realistic logarithmic velocity profile was established by modifying von Karman-Prandtl equation. The analysis indicates that the parameters are associated not only with the acceleration or deceleration of currents but also with sand ripples. The changes of boundary layer parameters are in negative correlation with the characteristic acceleration.