Velocity Profile in Shallow Coastal Waters

In a series of field measurements the mean velocity profiles were measured during the acceleration and deceleration phases of tidal currents off the east and south coasts of England. Salinity/temperature profiles were also measured. The sites have simple geometries, and the beds were covered with sand. The measured velocity profiles consist of an outer region, encompassing 90% of the boundary-layer thickness; an inner region adjacent to the bed; and an overlap region between the outer and inner regions. The velocity profiles in the outer and overlap regions obey the defect law and the usual log-law, respectively. The coefficient of the skin friction was high, mainly due to bed forms.