How can I tell if my house or property is located within the floodplain?
What does the "100-year flood" mean?
The City of Keller is a participating city in the Federal Emergency Management Agency’s (FEMA) National Flood Insurance Program (NFIP). Ordinances are in place that govern and restrict development within the NFIP effective floodplain. In response to rising costs of taxpayer funded disaster relief, the NFIP was developed to provide homeowners affordable insurance to protect against flood losses based on their potential risk of flooding.
The City of Keller, under direction of the City Council, developed a Master Drainage Plan which examined all storm drain systems and channels within the city for ultimate developed flow rates in anticipation of future development occurring within the City and upstream. Ultimate developed flow rates look at the entire watershed (area draining to a point) as though completely developed. The City requires all development to meet not only the FEMA NFIP criteria, but also the fully developed condition flow rate floodplains on file with Public Works.
Any development involving manmade changes including fill, excavation, fences, pools, habitable structures, etc. that are adjacent to a drainage channel must complete a floodplain development permit and may be required to submit a full hydrologic and hydraulic analysis depending on the potential impact and location.
FEMA has important information and FAQs for homeowners, developers, etc. Additional information can be found at www.floodsmart.gov.
Lending institutions determine whether a property is within or outside of the NFIP floodplain boundary by using Flood Insurance Rate Maps (FIRMs). The City of Keller has the effective maps on file for review. You may also purchase, view or print a FIRM online at msc.fema.gov. These maps are legal documents and may or may not represent actual conditions. If there are discrepancies in regards to a mapped floodplain and actual conditions that a property owner wishes to explore there are means to contest the findings.
What is a Floodplain
A floodplain is flat or nearly flat land adjacent to a stream or river that experiences occasional or periodic flooding. It includes the floodway, which consists of the stream channel and adjacent areas that carry flood flows, and the flood fringe, which are areas covered by the flood, but which do not experience a strong current.
In the United States the National Flood Insurance Program regulates development in mapped floodplains based on the 100-year flood (A one-hundred year flood is calculated to be the maximum level of flood water expected to occur on average once every one hundred years). As shown on official Flood Insurance Rate Maps, a typical floodplain is divided into a floodway, which includes the stream's channel and any adjacent areas that must be kept free of encroachments that might block flood flows, and other Special Flood Hazard Areas in the flood fringe that are subject to inundation by the 100-year flood.