Integrating GIS and Remote Sensing with Flood Simulation Models for Flood Hazard Mapping and Disaster Mitigation

The objective of the study was to prepare a flood hazard map for risk mitigation and early warning.
A frequency analysis was conducted using river discharge data form of past records to obtain river discharges for different return periods.

      A Digital Elevation Model (DEM) was created using the contour and spot elevation data from the digital topographical maps prepared by the Survey Department of Nepal. The Triangular Irregular Network (TIN) was used in HEC-GeoRAS environment to extract terrain and riverbed information. HEC-RAS model was then used for flood simulation using estimated discharge for different return periods, landuse/landcover conditions and terrain and riverbed information. 
      A flood inundation map with flood depths was produced and overlaid with population density and landuse/landcover map to prepare a qualitative flood hazard map. An early warning system was proposed by making use of stage versus discharge curves at the upstream of the Bagmati river. A few flood mitigation measures such as landuse regulation and flood proofing including minimum plinth levels for buildings were suggested. Critical river sections for structural measures were also identified to formulate strategies for flood control planning and management.