Understanding and Evaluating Your Individual Flood Risks

Last week, portions of St. Tammany Parish were inundated with heavy rains and isolated flooding.  Initial assessments indicate that the events could be considered 500 year to 1,000 storm events (https://www.nola.com/news/weather/article_036bce24-96f8-11ea-802d-5f44931373be.html).  The below is provided to offer homeowners and businesses a better understanding of flood risk and some public resources available to  assess your individual risk.

1. The magnitude of the storm event is determined through statistical analyses and the “year” storm is meant to signify the probability of the event happening in a 1-year period.  For example, a 100-year storm has a 1% chance of occurring each year while a 500-year storm has a 0.2% chance of occurring each year.  While the probability is low, it is possible that 100-year or even 500-year storm events could happen more frequently each year.
2. FEMA Flood Insurance Rate Maps (FIRMS) that provide the Base Flood Elevations (BFE) are available electronically from the Louisiana State University Ag. Center (http://maps.lsuagcenter.com/floodmaps/).  This website provides some additional guidance regarding the differences between the Effective FIRM and Preliminary or Future FIRMS.  The website also provides a map allowing you to search for your home and business address.  The map will provide the boundaries of FEMA  flood zones and the BFE.  Storm event modeled for the FIRM Base flood elevation is a 100-year storm event.
3. FEMA has provided Base Level Engineering assessment data using high resolution ground data to create technically creditable flood hazard information that may be used to expand and modernize FEMA’s current flood hazard inventory.  The map can be accessed at https://webapps.usgs.gov/infrm/estbfe/.  Select Property Look Up to search your individual home or business address.  Select Data Layers to view the estimated flood extent and flood water depths for a 100-year and 500-year event

Please feel free to reach out to Firm Principal, John Catalanotto, PE (john.catalanotto@fairwayce.com) if Fairway can be of assistance.