An experimental investigation of broken wave over mud bed

The physical nature of the beach profile, wave condition and sediment prope rty of muddy coast are different from those of sandy coast. At muddy coast, which is characterized by almost flat or horizontal bed close to the shore line, wave can break with significantly low value of the incipient breaker height to water depth ratio. The effect of reduced incipient breaker heigh t on surf zone dynamics are not known when wave break with spilling action. For the purpose of correct estimation of the coastal process at muddy coas t, it is important to know the dynamics of surf zone in comparison to that of sand coast. In the present study, the hydrodynamics under breaking wave over mud bed has been examined by carrying out a number of laboratory exper iments. The dissipation of wave, velocity and turbulence field was observed for varying wave conditions over flat and very mildly sloped beds. The inc ipient wave breaking condition was found to be the most important parameter to characterize the surf zone dynamics over mud bed. The contribution of m ud bed to dissipation of broken wave was determined by observing the nature of wave decay over rigid bed. The size of the surface roller, which is typ ically considered as constant, was found reduced with the decrease of incip ient breaker height over flat bed. The mean velocity and turbulent energy w as significantly dependent on the beaker height to water depth ratio. The v ertical transfer of turbulence was higher when the bed was sloped in compar ison to the case of horizontal bed.