| Abstract | Flood causes a large inundation area in the Mekong Delta of Vietnam every year. It affects
socio-economic activities of people, and damages assets in flood prone area. Therefore, flood
prediction with detailed information of spatial extent, depth and duration of inundation, and
estimation of damages caused by floods are very important for flood disaster mitigation
measures such as relief works, preparedness, etc.
In this study, Vietnam Rivers and Plain model or VRSAP model is calibrated using the severe
flood of the year 2000 in the Mekong Delta of Vietnam. The simulated results including
submerged area and peak water level at selected gauging stations show reasonably good
agreement with observation. Flood frequency analysis using the Pearson type III distribution
was carried out to obtain flood magnitudes corresponding to various return periods at Kratie.
Based on the calculated flood peaks and observed flood hydrographs at Kratie for the year
1996 and 2000, flood hydrographs of different return periods were developed using the Linear
System model. The first peak of flood, for each of the return period, calculated based on the
year 2000 flood is greater than that calculated based on the year 1996 flood. The occurring
time of peaks calculated based on the year 2000 flood is earlier than those calculated based on
the year 1996 flood.
The calibrated VRSAP model was applied to predict flood information of spatial extent, depth
and duration of inundation at various return periods. Results indicate that the areal extent of
submerged area due to a flood of any return period based on the 1996 flood is greater than the
one simulated based on the 2000 flood. However, the completely opposite trend is observed
for the flood duration. The overall effect of this analysis is that the damages caused by the
flood of year 2000 are much higher than the one by the flood of 1996.
Based on the predicted floods of different return periods and the field surveyed data of the
year 2000 flood, the damages are estimated, in terms of direct, indirect, and intangibles
damages, for different type of land use, namely residences, commercial, industrial,
agricultural, and infrastructure. Damage-frequency curves for various types of land use are
developed based on the estimated flood damage caused by various return period floods. The
damage-frequency functions for residential and non-residential sectors are found as linear
function. The damage-frequency functions for agricultural and infrastructure sectors are found
as power function. These curves are useful for rapid damage estimation in planning for relief
works, preparedness activities, etc. |