Numerical study of wave transformation over fringing reef flat

The evolution of wave shapes on fringing reefs is closely related to nearshore nutrient delivery and sediment transport of coral sand. It also plays a crucial role in determining the design and construction of the structure on the reef flat. Therefore, investigating the evolutions of wave shapes on the reef flat is necessary. In this paper, the FUNWAVE 2.0 numerical model was employed to simulate irregular waves, which propagate over different types of fringing reefs, and the influence of forereef bottom slope and reef roughness on the evolution of wave shapes was discussed. Results showed that an increase in the absolute value of wave asymmetry is moderated by the slope of the forereef bottom becoming steeper. Moreover, the absolute value of asymmetry for the smooth bed condition is slightly larger than that for the rough bed condition. However, the wave skewness on different fringing reefs is almost the same. This indicates that the forereef bottom slope significantly influences wave asymmetry variation and the effect of reef roughness is relatively small. However, the abovementioned factors have a negligible effect on the wave skewness. In conclusion, the empirical formulae for wave skewness and wave asymmetry on the reef flat by combining the influence of forereef bottom slope and reef roughness are recommended.