mag

Malaysia Water Research Journal
Table 2. Water level station
Station Latitude Longitude
WL A 3° 31' 50.400" N 103° 27' 44.000" E
WL B 3° 48' 35.600" N 103° 20' 09.800" E
3.3 Numerical Model
Analysis of the historical changes in bathymetry of the study area was carried
out by making a comparison between the observed bathymetric data in 1952
and 2014. The bathymetric data for year 1952 is presented in fathoms unit, where
1.0 fathoms unit is approximately 1.83 m. Analysis of morphological changes
were implemented by using Geographic Information System (GIS) of ArcMap
version 10.1. Subsequent conversion unit was done to enable comparisons to be
made. MIKE 21 software (DHI) was used in this study. The module hydrodynamic
(HD), spectral wave (SW) was utilized for the analysis of wave, whereas sediment
transport (ST) was used for sediment analysis. Hydrodynamic model was built in
mesh generator and the boundary cover from Beserah to Kampung Alur Pasir
where the bathymetry data were observed as ploted in figure 5. Bathymetric
profile was generated by combining data extracted from MIKE C-Map and
bathymetry data obtained from the field measurement campaign. Once the
data is interpolated, the boundary conditions for the study area were determined
by the Global Tide Model MIKE 21.
Modelling work was run for 14 days, that is similar temporal period done for
the marine data campaign and covers a full tidal cycle. Simulations were carried
out on 22 May – 8 June 2014 with a lag of 60 seconds and the concept of flood
and dry was applied in this model. The seabed resistance value used is between
25 m1/3/s - 60 m1/3/s, depending on the sea depths. According to Lee (2011),
coastline with the presence of plants such as mangroves have rough and high
resistance values for the seabed.
20
a) b)
Figure 5. The numerical model developed showing a) mesh generator and b)
topography and bathymetry data
Institut Penyelidikan Hidraulik Kebangsaan Malaysia (NAHRIM)
National Hydraulic Institute of Malaysia (NAHRIM)