Flood Hazard

Know Your Flood Hazard

Flood are among the most frequent and costly natural disasters. Flood hazard is not just related to flash flooding. Flood hazard refers to risk associated with mapped flood-prone areas of your community, and areas of poor drainage, localized street flooding, and other related flood risk areas.

Houston’s unique in that its flat terrain, large amounts of impervious cover (concrete), slowly-absorbing soil, and potential for thunderstorms, tropical storms, and hurricanes all combine to form ideal conditions for flooding. Due to its humid-subtropical climate and proximity to the coast, Houston is susceptible to a large amount of rainfall that is often too great for its infrastructure and bayous to handle. Once the City’s ditch and storm sewer networks are inundated with storm water runoff, streets become secondary drainage facilities.

Most stream flooding areas have been mapped by the Federal Emergency Management Agency (FEMA); however, not all flood-prone areas, areas with poor drainage, or localized street flooding have been mapped. Your property may never have been flooded or may be shown on the FEMA flood maps to be outside the mapped limits of flooding.

Most areas of the City have yet to see the record 100-year flood event, which is a 1% chance of occurring in any given year. There is no guarantee your property will never flood. Statistics show that the 1% annual chance flood has approximately a 26% chance of occurring over a 30-year mortgage period.

For those living outside the 1% annual chance floodplain, also referred to as a Special Flood Hazard Area (SFHA) on the FEMA flood maps, flooding is still possible. Approximately 25% of all flood claims occur outside the SFHA in areas considered minimal to moderate flooding. What does that mean for City of Houston residents? It means that everyone can, and should, have flood insurance, which is not covered under a standard homeowner policy. You can determine your property’s flood zone at http://msc.fema.gov/portal and get information on flood insurance at www.floodsmart.gov.

The following video from FEMA’s National Flood Insurance Program (www.floodsmart.gov) shares two views of the same flood—one with flood insurance and one without it:



Public Information & Flood Information Assistance

The City’s Floodplain Management Office is part of the Department of Public Works and Engineering located at the Houston Permitting Center: 1002 Washington Avenue, Houston, TX 77002. It provides comprehensive flood information to the public. Residents may access flood information from the City by meeting with a representative in person, by phone at 832-394-8854, or via e-mail at fmo@houstontx.gov.

The Floodplain Management Office provides flood information, including flood zone determinations for specific addresses, floodplain permits for proposed or existing structures, lowest floor elevations, and elevation certificates, as available. City staff can assist residents in determining localized areas with known flooding and drainage problems not shown on FEMA flood maps, and approximate depth of potential flooding and past flooding at or near their property. The City also guides residents in floodproofing and other mitigation techniques, along with funding options for mitigation projects to reduce flood risk to their property.

Flood Insurance rate Maps (FIRM)

The City provides a map information service which enables all residents to determine the flood zone of a specific property. Paper copies are available for viewing at the City’s Floodplain Management Office, or electronic maps may be viewed and printed online for free at the FEMA Flood Map Store at https://msc.fema.gov/portal. The information can also be accessed via the Public Works & Engineering Department’s Geographic Information and Management System (GIMS): http://www.gims.houstontx.gov/PortalWS/MainPortal.aspx. For assistance using GIMS, see the GIMS Help Guide.