5. Conclusions
This study provided an opportunity to use both hard and soft
engineering techniques in coastal rehabilitation. The breakwater
intervention is mainly aimed at reducing the amount of wave
energy reaching the shore in order to shelter the transplanted
mangroves and augment deposition of sediments. Incorporation of
this hard structure in mangrove restoration in Sg Hj Dorani was
found to be conducive to provide a suitable environment for the
success of the effort. Field observations indicated that mangrove
saplings transplanted in the area sheltered by the breakwater were
protected well against wave action. The results of the last monitoring
carried out eight months after initial restoration demonstrate
that approximately 30% of the original saplings survived. A
substantial volume of sediment was retained on the beach in
a short period of time indicating the efficiency of the coastal
structure in raising the beach elevation. The accretion in the lee of
the breakwater is anticipated to continue since mangrove restoration
will improve sediment stabilisation. Although field observations
illustrate that the project is successful in achieving its goals,
monitoring is required to continue for a longer period of time (i.e.
several years) to determine the long-term efficiency of the rehabilitation
effort.
The breakwater structure was designed as simple as a homogeneous
rubble mound without layered cross-section or filter layer,
and bamboo stems were employed as foundation mats to reduce
the construction cost and time. This project is a model for integrated
approaches to mangrove restoration which is worth replicating
in the other degraded sites with relatively similar
characteristics.