Mapping Flood Risk Buildings : Using QGIS and HEC-RAS

Abstract

This thesis is a comprehensive study of 2D hydrodynamic flood modelling of Koshi river situated in Eastern territory of Nepal. In 2008 August Koshi levee breach caused a devastating flood event that affected millions of people from Nepal and India. Every year Koshi causes significant impact to the people and infrastructure in the catchment area. Thus, this thesis Studies a small portion of Koshi catchment area and establishes the flood inundation scenario in case of levee breached in its peak flow. The output of the study demonstrated the probable number of buildings in risk in the case of flooding. As for the occurrence of flooding, it was assumed that in peak discharge condition the levee on the eastern side would be breached in a point. This thesis also included a brief description of data preparation techniques and the required tools. Flow rate data from gauge station, building’s data from Arial imagery and OpenStreetMap, DEM data form JAXA and HydroSHEDS were used to meet the objective.