Abstract:
Flood hazard is assessed for the data scarce lower Bharathapuzha basin in Kerala, India, using a hydrologic-hydraulic approach. Lmoment-
based regional flood frequency analysis along with a non-dimensional analysis of hydrographs is used to generate scenarios
for flood hazard assessment. A fully hydrodynamic 1D river flow model is calibrated for the rivers of lower Bharathapuzha basin for
the year 1992 and validated for the year 1994. The widely available SRTMDEMis used to extract river cross-sections and the limited
available discharge and water level data are used to carefully calibrate the 1D river flow model. Subsequently, a coupled 1D-2D flood
inundation model is used to simulate the flood inundation extent for the year 2002. In the absence of LIDAR data, a cartographic
DEM derived from readily available topo maps is used as an input in the coupled 1D-2Dmodel. Further, in the absence of microwave
SyntheticAperture Radar (SAR) data, the flood inundation extent is validated using the readily available optical IRS-1DWiFS sensor
data which is mainly intended for vegetation and drought monitoring. A suitable methodology is used to delineate flood inundation
extent from the partial cloud-covered WiFS image. The regional flood frequency estimates and the calibrated and validated flood
inundation model are then used to assess the flood hazard.
