Abstract

A GIS Flood Tool for Rapid Inundation Mapping
Track: Water Resources
Authors: Kristine Verdin, Melissa Mathis, James Verdin

Many developing countries lack objectively produced flood inundation mapping for use in mitigation and response planning. Conventional methods, involving field surveys and hydraulic modeling, are often too costly. Organizations with a global perspective on flooding lack a globally-consistent approach for flood hazard characterization. To address these needs, tools were developed for flood mapping with globally-available or locally-produced topographic data.

The resulting GIS Flood Tool (GFT) was developed to rapidly produce flood inundation patterns corresponding to specified river discharge or stage. The GFT uses a DEM along with the Manning equation to construct a stage-discharge relationship for each stream cross-section. The stage-discharge relationship is used with a "Relative DEM to rapidly map the inundated extent. The inundation patterns can be used along with ancillary GIS layers to assess vulnerability to flood events and support preparedness planning.

The GFT was implemented and tested in Eastern Africa. Results compared favorably with HEC-RAS modeling.