mag

Malaysia Water Research Journal
4b after monsoon season ended. Figure 5 showed the analysis carried out to
investigate the changes of profile at sites due to NEXC Block installation. Based
on the analysis it is proven that water level, wave magnitude and beach profile
are the main parameters in determining scour impact at the toe of structure, as
per results in the study in 2D wave flume laboratory.
a) 2D Beach profiling analysis b) Plan view of beach profile
changes in 3D
Figure 5. Analysis of beach profile changes.
6 CONCLUSIONS
In general, the rate of erosion is dependent of wave magnitude and water
level. Higher wave breaks earlier and farther from the beach as compared to
lower wave. However due to wave energy by higher wave, even after breaking,
the wave propagates further inland with higher volume. Thus higher wave
causes more erosion as compared to lower wave height, as same goes to water
level parameter. As the water level increases, due to less bathymetry effect, the
breaking point also moves to a point nearer to the beach thus leads to higher
erosion rate. The experiment thus proves that the worst erosion occurs during the
combination of high water level and high wave magnitude.
NEXC Block installation is found successfully controlled the erosion within the
interest area. Sand loss due to erosion and scour is limited to only at the face of
the structure, whereas the backside of installation is found stable. However during
high water level and high wave event, scouring problem is prevalent. Hence
scour protection units is proposed to be combined with NEXC Block installation.
In a long term period, sediments are returned back to the beach hence naturally
expanding the beach. Result of simulations in laboratory works in 2D wave flume
has been validated using actual site measurement. Hence physical experiment
approach is still considered as one of the best approaches in conducting study
within coastal zones. For future work study, focus can be given to improve the
efficiency of scour protection. It is also suggested that the material of NEXC Block
is transformed into alternative environmental friendly materials.
Institut Penyelidikan Hidraulik Kebangsaan Malaysia (NAHRIM)
37
National Hydraulic Institute of Malaysia (NAHRIM)