Investigation of the impact of macroalgal mats on sediments pattern in unidirectional and wave-induced flows

In this research, the impact of macroalgal mats on sediment pattern was studied experimentally. To achieve this object, a series of experiments were conducted in a large flume for different flow conditions and bed covers. The Power Spectral Density (PSD) method was used to separate wave-induced velocities from turbulence. The results showed that the separation of wave-induced orbital velocity from turbulence is possible by using the power spectral density (PSD) method. The sediment results revealed that the bed level variations in bare bed were more severe than in algal bed. So that, the range of its variations in bare bed was three times of algal bed especially in wavy flow conditions. In addition, the average number of ripple crests per meter decreased and the relative ripple wave length increased with increasing of flow discharge. Also the bedload quantity in presence of algae decreased by 80% in unidirectional flow (current) as well as 15% in wave-induced flow (combination of wave and current) conditions.