Hydraulic Performance of Composite-Type Seawalls Applied in Malaysia

This is a report on the Final Year Project titled 'Hydraulic Performance of Composite-
Type Seawalls Applied in Malaysia'. Composite-type seawalls were stacked armour
stones or wave dissipating blocks fronting the vertical seawalls to reduce waves
overtopping. Under certain weather condition and storm action in Malaysia, waves
overtopping would be frequent and violent where hinterlands are prone to the risk of
flooding and damaged to infrastructures. The objectives ofthis project were to study the
existing types of composite seawalls applied in Malaysia and conduct risk assessment
on the selected composite seawalls. Three models are fabricated which were concrete
block, composite seawalls using quarrystones and concrete cubes as armour units. The
models were constructed ona scale of 1:15 using concrete mortar. Tests were conducted
in a flap-type wave generator in the UTP Hydraulic Engineering Laboratory. First part
of the project only highlights two preliminary tests which were the determination of
wave period, Twith respect to frequency,/and determination ofincident wave height,
Hiwith respect to wave period, Tin four different water depths (18, 20, 22 and 24 cm).
The results were used in the second part of the project which was the determination of
overtopping rates, qfor three different models of seawalls for d= 18, 20,22 and 24 cm.
The overtopping rates were then analyzed with respect to wave steepness, H/gf and
incident wave height, Hh It is founded that q increased as Ht and dincreased. Then risk
assessment on pedestrians, vehicles, buildings and embankment seawalls are made. The
tolerable overtopping rates developed by Owen (1994) are used as guidelines to the
assessment. Observed from the assessment, the waves overtopping values were
hazardous to pedestrians, vehicles and buildings. As for embankment seawalls, the
values cause no damage. It is concluded that overtopping rates are influenced by Hi and
dwhile further research can be done in order to minimize the hazards to pedestrians,
vehiclesand buildings