USGS Indiana-Kentucky Water Science Center

Flood Inundation Mapping

Creating a Flood-Inundation Map Library

A FIM library is the collection of high-resolution maps, technical reports, GIS layers, and the online maps (available through the USGS FIM mapper web site) for a particular section, or reach, of a stream or river. Building a FIM library includes

Phase 1: Site Selection and Data Collection

During this phase, we collect information about potential sites including

  • stream gage datum elevation;
  • historic flood peak information;
  • stream gage rating curve;
  • high-water mark data;
  • historic flood profiles;
  • FEMA flood insurance study (FIS) materials;
  • existing hydraulic models;
  • existing AHPS text descriptions of the local impacts to property, structures, and roads; and topographic/bathymetric data.

Phase 2: Data Collection and Modeling

Models are selected for each study. Generally, a one-dimensional step-backwater model developed by the U.S. Army Corps of Engineers is used.

Phase 3: Geospatial Processing

Water-surface profiles from the hydraulic model and digital elevation model (DEM) data are combined in ArcGIS, a geographic information system.

Phase 4: Map Production

GIS layers from step 3 are combined with base map layers to form the inundation maps.