Geoscience Reference
In-Depth Information
5. Model Simulation Results and Discussion
After applying the methods and parameters mentioned above, the following
simulation results were obtained. Figure 2 shows simulated results of the
maximum flood extent on September 28, 2000, and that on October 9,
2003. The simulated results reproduced well inundation processes of the
year, namely, in drying season water flows only in the main rivers, while
during flooding season flood water spills out gradually to adjacent areas,
and consequently, flood water expands out both sides' floodplains of rivers.
Based on location of stations and available hydrologic data, we setup five
sites to examine calculated water levels, namely Kompong Cham, Kompong
Luong, Prek Dam, Koh Khel, and Neak Luong (Fig. 3), and four cross-
sections for discharges output, as Kompong Cham, Prek Dam, Koh Khel,
and Neak Luong (Fig. 4). Figure 3 shows that the simulation water level
at Kampong Cham met well with observed data, while at the others sites
they differ to each other; about 0.5-1 m at Kompong Luong, Koh Khel and
Neak Luong, and from 1.5-2 m at Prek Dam station. Peak discharge of the
model simulation at Kompong Cham (73,000 m
3
/s) is higher than result
simulated by MRC (64,000 m
3
/s). Simulated flood hydrograph showed that
peaks of flood wave at Kompong Cham is sharp and high while they are
flat and lower at Neak Luong, Koh Khel, Prek Dam, that correspond well
to real situation of high flood level at upstream and inundation extent at
downstream reaches. Result verifications of simulation flow-fields and water
levels suggest that, Manning roughness coecients used in the simulation
are small (
n
=0
.
020 for main rivers and
n
=0
.
025 for floodplains). This
makes the simulation flood flows faster than in real state producing high
Fig. 2. Simulated results of the maximum flood extent on September 28, 2000 and that
on October 9, 2003.
