Preparation of the Flood Inundation Map and Study of its Impact on Adjoining Areas due to Brahmaputra River using HEC-RAS

In the present study, the HEC-RAS model is being used to study the effects of the peak floods at different crosssections of Brahmaputra river for 10, 20, 50 and 100 years return period. For estimation of floods having 10, 20, 50 and 100 years return period, Gumbel’s extreme value distribution method has been used. Also, for the estimation of the flood havoc and to look into its effects, 20 years return period flood has been considered. These fifty cross sections covering the 100 km length of river, which is more flood prone, have been taken for the study. The results of the study show that the heightening of left embankment is needed which varies from 0.21 m to 1.48 m and for right embankment it varies from 0.1 m to 3.04 m. Further, the flood inundation map has been prepared for the study area and this map is used in Google Earth Pro for the 3D visualization of the depth of flood. The results of the present study indicate that suitable flood mitigation strategies need to be implemented which will effectively minimize the flood hazard of Brahmaputra river system as well as to save the lives and property to a large extent.