Bed shear stress distribution over a composite beach profile

Abstract

The mechanism of onshore-offshore movements of the bottom sand and the local bed movement around marine structures fan be better understood by defining the bed shear stress distribution. In order to obtain the variation of the bed shear stress over horizontal and following sloping bottom ie from intermediate to shallow water conditions, a series of measurements have been made to clarify the structure of the wave boundary layer along the composite beach by using a Constant Temperature Anemometer. The bed shear stress measurements have been done on both the sloping beach and the horizontal bed which is offshore region. The results clearly show the effect of the wave shoaling process on the bed shear stress. The maximum bed shear stress value has been found at the plunging point due to strong vortex generation and the turbulent structure, however, the periodic component of the bed shear stress is still of the periodic character like the offshore region.