Khoksabari Union of Sirajganj Town is surrounded by a network of rivers namely the
Jamuna, the Bangali and the Karatoa which makes the Union vulnerable to flooding. The
present study assesses the hazard and vulnerability of riverine flood in a flood prone area
using Remote Sensing (RS) and Geographic Information System (GIS). In the context of
flood hazard and vulnerability assessment, flood frequency analysis is carried out to assess
flooding for different flood magnitudes. Flood inundation maps are prepared based on
DEM and satellite image for different risk elements using ILWIS software. LANDSAT
satellite images have been downloaded and used to develop land use map in the study
area. The land use map is used for mapping of settlement and fishery by using ILWIS
software.
The vulnerability function is developed for preparing vulnerability maps for settlements
and fisheries. For the development of vulnerability function, depth-damage relation has
been developed. Present monetary values of settlement and fishery damage are collected
through field survey from actual flood of the study area. Vulnerability functions of
settlements and fisheries are used to produce raster-based vulnerability maps.
The flood frequency analysis shows that the Pearson Type III distribution is the best fitted
distribution for flood frequency analysis in the study area. In 100-year return period flood,
inundation percentage of the total agriculture, settlement, fishery and road areas are 48, 35,
53 and 38, respectively. High land (F0) of the study area is 55% which is not much
inundated in normal monsoon flood. Vulnerability scaled as low, very low, moderate, high
and very high vulnerable settlement areas are found to be 17, 12, 3.43, 1.03 and 1.35
percent, respectively for 100-year flood. These correspond to a maximum of 20%, 40%,
60%, 80% and more than 80% damage of the respective settlement areas. In 100-year
flood magnitude, low, very low, moderate, high and very high vulnerable fishery areas are
found to be 18, 19, 9, 3 and 4 percent. These correspond to a maximum of 20%, 40%,
60%, 80% and more than 80% damage of the respective fishery areas. The results of this
study may be useful for future flood damage mitigation plan in the study area.