Flood Hazard Assesment Question

04-02-2014 12:16 PM
New Contributor
We are mapping flood hazard zones and I am wondering if anyone could help me with the following:
We have an address points shapefile located within a FEMA flood zone- addresses only, not Lat/Long coords
We have 5 ft. interval contour lines (we may be able to get lidar based 1 ft contours)
We have the FEMA polylines which give base flood elevation estimates for a 100 year event
We can obtain a DEM of the area if needed
The final product of this project is to create a query or model which will add three new fields to the address points attribute table: 1. Elevation of the address point based on the contours (or DEM if necessary), 2. the FEMA flood elevation associated with that address point and 3. the difference between the two. The lower the difference between the flood elevation and the address elevation, the    more at risk that address is (which can then be symbolized).
The County Office of Emergency Management will use this model to assess which homes are at the greatest risk during flooding (and show FEMA the grant $ is being used properly).
Any tips, pointers or suggestions which tools will be needed would be greatly appreciated. We will soon have access to the complete ArcInfo package and associated tool extensions.
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Esri Contributor
Hi Jerome;
Take a look at the Flood Planning Map (http://solutions.arcgis.com/state-government/help/flood-planning/workflows/) if you have not already done so.  It can be used to identify which homes are at risk based on the flood elevation level.  Use the DEM to create flood impact areas for each flood level using the Create Flood Impact Area tool.  Then instead of using the Public Infrastructure layer or Facility Site Points you could use your address points (after they have been geocoded) as an input layer into the Create Flood Impact Plan tool. This tool will overlay the address points with the flood impact areas to identify which homes will be flood at each flood level.  Hope it helps. - Walt
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