Learn about which historic floods were recreated for Flood Factor.
Types of historic floods
The First Street Foundation Flood Model has recreated 55 major historic floods, including both riverine floods as well as coastal floods associated with hurricanes, tropical storms, and nor’easters. The floods are modeled simulations recreated and calibrated using recorded flood data and validated against known government flood claims.
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Rain flooding |
Riverine flooding |
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Tidal flooding |
Surge flooding |
While heavy rains are often associated with both types of flood events, they are not included as part of the recreated flood models. The modeled historic floods only include storm surge from coastal events and only river overflows from inland events. The current methodology used does not allow for the recreation of flood events from heavy rains, and as such, events that contained a lot of rain may not look exactly as documented from other sources.
Historic floods on Flood Factor
Currently, locations on Flood Factor only show information for the recreated historic floods that likely impacted them. Properties are considered to have been impacted by a historic flood if its modeled recreation indicates that flood water reached the largest building on the property or, if there are no buildings, the center of the property lot. Neighborhoods, zip codes, cities, and counties are considered to have been impacted by a historic flood if any of the properties within their boundaries were impacted.
Provide past flooding information
The historic flood information shown on Flood Factor is not comprehensive, and does not include heavy rains. However, individuals are encouraged to share information if they know a location has flooded in the past, as this information will help improve the historic flood models and may be added to the database and shown on Flood Factor in the future.
