Multi-Hazard Vulnerability Assessment Tool (MHVAT)

The Coastal Risk Atlas (CRA) vulnerability assessment process can be broken down into three key elements: hazard identification and analysis, demographic identification and analysis, and local infrastructure identification and analysis. Of these three parts, processing tasks are required by the hazard and demographic analysis. The focus of this application is related to the hazard assessment process.

What storms affect my area? Identifying what hazards affect an area is the first priority. Within the CRA, we are looking at three hazards: storm surge inundation, flooding, and wind speeds due to hurricanes. Along the Gulf of Mexico and Atlantic coasts, hurricanes are probably one of the biggest storm concerns. Hurricanes can bring flooding, storm surge inundation, high wind speeds, and even tornados. Many of these byproducts of hurricanes can occur separately as well. Each hazard is analyzed on it's own and assigned a vulnerability index that is based on a parameter (i.e. storm surge is based on the category of storm, flooding is based on the zone). Once these hazards are assessed, they are then combined and the vulnerability indices are summed to give a composite look at the area relating to hazard vulnerability.

The CRA uses data from a variety of sources. Outputs from the National Oceanic and Atmospheric Administration's (NOAA) Sea, Lake and Overland Surges from Hurricanes (SLOSH) storm surge model runs are used as the storm surge inundation data. The Federal Emergency Management Agency (FEMA) provides the flood zone data and the wind speed data. The wind speed data is based on the National Hurricane Center's Maximum Envelope of Wind (MEOW) model.

The processes involved for each assessment are defined in their respective help pages. The assessments that will be processed are chosen in the first step by checking the boxes next to the hazards to be assessed. First, the user selects the hazard concerns they will be performing assessments for. Below this area, the user chooses whether they need to perform any clipping functions on the data, and what layer will be used in this action. At the bottom of the page are three buttons: Help, Next, and Cancel. The Help button opens a help document about the MHVAT tool. The Cancel button closes the tool and if new feature layers have been created, they will be deleted from the map and directory. The Next button opens the first available hazard assessment.



At the end of the assessment, all new shapefiles that were created through the assessment are listed in a box and will be unioned into a composite hazard layer. A new field, 'TOT_RSK', is created that will hold the summed values of the vulnerability indices across all hazards. You can specify the name and location of the new shapefile by using the textbox and folder button. Also, if you choose, there is a check box that will allow you to create a map layer to show the graduated symbology on the new 'TOT_RSK' field.



This last form is optional. The form allows you to create a symbology layer using the 'TOT_RSK' field and choosing some type of classification scheme. The Classification Method and Classes boxes with adjust how the values in the 'TOT_RSK' field are displayed in the grid. You may also type in new labels that better describe the range of values, for example, "LOW" or "MEDIUM".