A floodplain is an area that will be inundated by a flood from a river, creek, ditch, lake, or other source of flooding.
A 100-year flood is the flood that statistically has a 1% chance of occurring each year.
A 100-year floodplain is the area that will be inundated by the 100-year flood. It is also the area that is referred to by FEMA (Federal Emergency Management Agency) as the Special Flood Hazard Area (SFHA). It is the area of a community where development must be regulated through a local ordinance conforming to the National Flood Insurance Program (NFIP).
How do I know if my property is in a FEMA floodplain?
Flood Insurance Rate Maps (FIRMs) produced by FEMA can be used to identify
FEMA floodplain areas. Several areas of flood hazards are identified on the
FIRM, including the SFHA. Using this map, a property can be located and floodplain
status determination can be made. FEMA maps are kept on file at City Hall
(map)
and may be viewed at any time. In areas not covered by these maps, special
flood studies may have been prepared. If so, they will also be available from
City Hall.
FEMA only regulates the 100-year floodplain for channels that have a watershed (area that drains to them) greater than 1 square mile. Smaller channels, as well as storm sewer systems, all have the potential to cause flooding.
Properties located in smaller watersheds are not included in FEMA mapping. Currently, the city requires new developers to establish 100-year flood elevations in areas not covered by FEMA, but there are some older developments that were not constructed under these regulations. Information regarding non-FEMA floodplains is available from the City. Contact either Engineering Services or Public Works for more information.
If my property isn't in a 100-year floodplain, could
it still flood?
Yes. Open channels, natural streams and enclosed storm sewer systems might
become clogged. Other obstructions, such as fences or landscaping, might change
the direction of flow, causing it to be collected into a portion of a system
undersized for that flow.
How are flood hazard areas and flood levels determined?
They are determined using statistical analyses of records of riverflow and
rainfall; information obtained through consultation with the community; topographic
surveys; and hydrologic and hydraulic analyses using computer models.
Can the floodplain location change?
Yes. Often the floodplain changes because of development upstream. Sometimes
errors are found on the FEMA maps and a revision can change the floodplain
boundary. Sometimes drainage way alignments shift, either naturally or by
development activities, changing the floodplain boundary. The current FIRM
designates the official FEMA floodplain boundary for insurance purposes, but
changes may be made to it in the future.
Floodplain insurance:
The city doesn't require floodplain insurance, it is a federal requirement.
The U.S. Congress established the National Flood Insurance Program (NFIP)
in 1968. Participation in the NFIP is based on an agreement between local
communities and the Federal Government that states if a community will adopt
and enforce a floodplain management ordinance to reduce future flood risks
to new construction in Special Flood Hazard Areas, the Federal Government
will make flood insurance available within the community as a financial protection
against flood losses.
What if my lender requires flood insurance but I don't
think my property is in the SFHA?
A lender may set requirements for flood insurance that are more stringent
than those set by FEMA. If the lender is requiring the insurance to meet mandatory
flood insurance purchase requirements, then the property owner and the lender
may jointly request that FEMA review the lender's determination. In response,
FEMA will issue a Letter of Determination Review (LODR).
Elevation Certificates:
An Elevation Certificate certifies the elevation of the lowest building opening.
It is used to provide information necessary to ensure compliance with applicable
community floodplain management ordinances, to determine the proper flood
insurance premium rate, and/or to support a request to alter the FIRM.
The City may require an Elevation Certificate prior to obtaining a Certificate of Occupancy on a new home due to floodplain management ordinances. You may need one if you feel that the flood insurance premium you're given is incorrect. You also may need one if you intend to provide FEMA with documentation showing that the FIRM is incorrect.
For additional information:
Engineer of the Day
913/895-6223 or eod@opkansas.orgNational Flood Insurance Program
1-800-427-4661FEMA
Map Service Center
1-877-FEMAMAPDivision of Water Resources
Kansas Department of Agriculture
785/296-2933