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USGS Flood Inundation Mapping Science

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Picture of historic flooding, Sept. 2009, in Atlanta, Georgia (Peachtree Creek)


Groundwater Monitoring in the Albany Area project home page. FIMI Toolbox home page

U.S. Geological Survey Flood Inundation Mapping Science

HAZUS-MH flood loss analysis tools

FEMA's HAZUS-MH is a nationally applicable standardized methodology that contains models for estimating potential losses from earthquakes, floods, and hurricanes. HAZUS uses Geographic Information Systems (GIS) technology to estimate physical, economic, and social impacts of disasters. It graphically illustrates the limits of identified high-risk locations due to earthquake, hurricane, and floods. Users can then visualize the spatial relationships between populations and other more permanently fixed geographic assets or resources for the specific hazard being modeled, a crucial function in the pre-disaster planning process.

HAZUS is used for mitigation and recovery as well as preparedness and response. Government planners, GIS specialists, and emergency managers use HAZUS to determine losses and the most beneficial mitigation approaches to take to minimize them. HAZUS can be used in the assessment step in the mitigation planning process, which is the foundation for a community's long-term strategy to reduce disaster losses and break the cycle of disaster damage, reconstruction, and repeated damage. Being ready will aid in recovery after a natural disaster.

HAZUS in detail:

HAZUS-MH Flood loss Software - Users and technical manuals:

Overview of FIM/HAZUS Methodology

HAZUS-MH is the principal software used to assess flood risk to affected populations, buildings, and other infrastructure in the U.S. However, while HAZUS is able to generate reliable assessments of flood risk, its usefulness is limited because it can only be run on a workstation by a trained operator with ESRI's ArcGIS software. In 2010, the USGS and FEMA began an effort to provide a solution to this problem by integrating HAZUS flood risk analyses with the USGS-produced flood-inundation maps and making these data available over the Web.

HAZUS analyses are first run offline for each stage increment at a given site. For example, a site with inundation maps and depth grids for 15 different stage intervals would involve 15 different HAZUS analyses. The data from the analyses of all the stage increments are then stored in a Web-GIS compatible database (PostGIS) for posting to the FIMI Web portal through a Web Application Service (WAS). Through the WAS, users can choose from two HAZUS damage and loss categories (figure 1).

Figure 1 - Schematic of FIM/HAZUS methodology

Figure 1 - Schematic of FIM/HAZUS methodology
The Quick Assessment tab (figure 2) displays loss analysis results for the entire study area, including displaced population, short term shelter needs, and economic losses for residential properties, total properties, and lost income from business interruptions. These data are provided for each of the site's stage intervals - as the user moves the depth slider on the left hand side of the window, the loss estimates change accordingly.

The Quick Assessment option also includes regional statistics for the study area, including area, number of Census Blocks, number of buildings (residential and total), population, and total value of exposed buildings.

Figure 2 - HAZUS Quick Assessment results for a single stage interval
Figure 2 - HAZUS Quick Assessment results for a single stage interval

The Loss by Census Block tab displays more detailed loss estimates for each census block in the study area. Drop down menus allow the user to select from over 90 different types of damage and loss categories (see appendix for breakdown). Results are displayed by census block in the FIM map viewer and change as the user changes the stage slider. Census blocks are colored to represent representative values for each stage interval (fig 3).

Figure 3 - HAZUS analyses by census block overlain on satellite imagery in the FIM viewer.

Additional Information

Each FIM/HAZUS site also includes the following information:

  1. Contact information for the analyst who conducted the HAZUS analysis
  2. Contact information for the analyst who reviewed the HAZUS analysis
  3. Access to flood inundation polygon shape files and depth grids
  4. Metadata

Interested in adding HAZUS flood loss analyses to a new FIM site?

Those interested in having a HAZUS analysis conducted for a new FIM site, or having a HAZUS analysis they've already completed added to a FIM site should contact:
Paul Hearn, Eastern Geographic Science Center, USGS Reston, VA, 703-648-6287,

HAZUS Level 1 Data Requirements

Best available DEM

Unless a LIDAR DEM is submitted, the highest resolution DEM available from the The National Map Seamless Server that covers the estimated flood extent will be used. The naming convention for a LIDAR DEM will be based on the shortened name of the site submitting the data and the state in which the site is located (For example a site in Reston, VA would name the DEM ResVA.tif). LIDAR DEMs can be submitted in formats other the TIFF as long as the format is supported by ArcGIS.

Estimated Flood Extent Shapefile

A single shapefile that includes a separate polygon for each estimated stage height. The naming convention for the shapefiles will be based on a shortened name for the site submitting the data and the state in which the site is located (for example a site in Reston, VA would name the shape file ResVA.shp.

The shapefile will to contain the following attribute fields:

Name Data Type Description
STAGE   Estimated stage Height in Feet associated with the Depth Grid
ELEV   Estimated NAVD88 elevation for the stage height
DSL   Estimate of discharge levels for a single steam in CFS

HAZUS technical working group

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