Flood Modeling with FEMA's HAZUS-MH MR3 Software

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Created by the Federal Emergency Management Agency (FEMA), HAZUS is a nationally applicable methodology for estimating potential damage, economic loss, and social impacts from disasters. In September 2007 FEMA released HAZUS-MH MR3 (which stands for Hazards U.S. Multi-Hazard, Version 1.3). Under the direction of Professor Larry Shubat, GIS students at the University of Akron’s Summit College explored the capabilities of the software in conjunction with ESRI’s ArcInfo digital mapping software.

The software is an additional tool in today’s digital mapping arena that supports preparations and mitigation for potential disaster planning. As described on FEMA’s website, "The HAZUS-MH Flood Model is capable of assessing riverine and coastal flooding. It estimates potential damage to all classes of buildings, essential facilities, transportation and utility lifelines, vehicles, and agricultural crops. The model addresses building debris generation and shelter requirements. Direct losses are estimated based on physical damage to structures, contents, and building interiors. The effects of flood warning are taken into account, as are flow velocity effects."

Students concentrated on the Flood Model for Canal Fulton, Stark County, Ohio. The first step was to load the software, which has a pretty healthy system requirement. Careful attention must be made to the data path and writing path.

Once the software is loaded, the process is straightforward, but procedures must be followed in order to create the desired end result. Initially the process is time-consuming, as the program gathers the initial data sets and processes the data into a flood model, but the results are amazing and well worth the effort.

Once software and data are installed the next step is to "Create a Region" of study. HAZUS makes this very easy with the "Create New Region Wizard." The students created their first study region of Stark County with a Study Case of Canal Fulton. The historic town of Canal Fulton is nestled in the northwest corner of Stark County near the Ohio and Erie canals and the Tuscarawas River.

Depending on the region study area, initial processing time can take fifteen to thirty minutes. The Region is then created and opened automatically in ArcGIS. Students projected the area into Ohio State Plane Coordinates (North) NAD 83 (feet).

Next, the Flood Hazard Type must be identified. Since the flood model relies on a Digital Elevation Model (DEM), the software is exceptional at connecting to the National Elevation Data set (NED) and extracting the needed DEM. To download the NED DEM, the user goes to Hazard | User Data. The DEM is also clipped to the region area based on region analysis by the software. NED DEM data is in meters, according to the metadata. (An operational note: an error may be returned by USGS due to download restrictions on the user’s computer. A work-around solution is to temporarily lower the security settings of the computer, download the file, then restore the security level.)

When the DEM data is downloaded and saved, it can be accessed by the User Data Browse button. The software will then build a study region DEM. For Stark County this took about 30 minutes. A symbolized DEM map was returned and the Stark County Region Area was automatically displayed with a 50% transparency.

The rest of the process follows a procedure to get to the final map product and summary analysis. Steps include:
1. Develop Stream Network
2. Determine Study Region for Hydrologic Modeling: This allows for processing of specified stream reaches and the topography to start the analysis and flood model building.
3. "Perform" Hydrologic Analysis: During the hydrologic analysis, HAZUS analyzes the discharge frequency relationships for each stream reach in the study case based on USGS data and equations. This information is stored at each node of each reach. This process only needs to be performed once for each reach in the study area. The stream reach areas will be denoted in red.
4. Perform Riverine Hydraulic Analysis: Once the stream network is developed and hydrologic analysis is done, the user can identify the type of flood analysis to be used for the study region. This is done by a Riverine Hydraulic Analysis, by inputting variables, for example for a 100-year flood analysis. This creates an RPD100 file that will give the height of the flood in feet (in this study case 16.8 feet for a 100-year flood is the maximum estimated depth of the flood). A flood plain is also produced.
5. Adding Symbolized Data: This step is simplified by using the default HAZUS "Inventory" main toolbar. For example, to map highway bridges, the user selects Transportation Systems, followed by the Table Type "Highway Bridges." Then, when the user clicks the "Map Button," all highway bridges in the region will be symbolized. Additional symbolized data may include Medical Care Facilities, Emergency Centers, Schools, and other items listed under the Inventory tool. A "selection by location" can then be performed to map only the symbols needed for the smaller study area.
6. Finalize Map: The Final Map (see image) is produced based on the purpose and scale of the analysis. The real tool is the analysis of the Summary Data which can then be used to review and update emergency plans based on the flood model analysis. When the specific "Analysis" is run, summary reports can be generated and viewed.

The End Result
Summit College’s GIS students discovered that the HAZUS default database for the analysis is excellent for an introductory class. The mapping capabilities and the Summary Report are valuable tools for emergency management personnel.

As summarized on the FEMA website, "HAZUS-MH is a powerful risk assessment software program for analyzing potential losses from floods, hurricane winds and earthquakes. In HAZUSM H, current scientific and engineering knowledge is coupled with the latest geographic information systems (GIS) technology to produce estimates of hazard-related damage before, or after, a disaster occurs."

Federal, State and local government agencies and the private sector can order HAZUS-MH free-of-charge from the FEMA Publication Warehouse.

Larry Shubat received his Master’s Degree in Geodesy at The Ohio State University in 1987, and a second Master’s Degree in Geography/GIS in 2005 from The University of Akron. He served 20 years in the U.S. Army in the Mapping, Charting and Geodesy field. He is currently teaching at Summit College at The University of Akron in the Surveying and Mapping and GIS Technology programs.

A 2.247Mb PDF of this article as it appeared in the magazine—complete with images—is available by clicking HERE