In an attempt to move toward more non-structural approaches to flood control, floodplain management plays an increasingly important role in the successful accomplishment of the Flood Control District's mission.
The floodplain management branch of the District is responsible for the following:
- Identifying areas susceptible to 100-year flooding, as defined by the Federal Emergency Management Agency (FEMA)
- Reviewing permit applications for proposed uses within the floodplain
- Identifying floodplain violations
- Protecting the natural and beneficial functions of floodplains
The District is required by law to take all reasonable action to inform County residents of the location of flood hazard areas.
Natural and Beneficial Functions of Floodplains
Floodplains are crucial for maintaining natural flood and erosion control. The County's mountainous desert topography, compacted soil, and countless washes and streambeds create flash flooding conditions during severe rainfall events, preventing rainfall runoff from quickly soaking into the ground. Floodplains contain and store this runoff until it dissipates.
Natural and beneficial functions of floodplains include:
- floodwater control
- water filtering and groundwater recharge
- habitats which support a wide variety of plant, wildlife and fish species
- environmental research sites
- recreational opportunities for parks, walking/biking paths, open space and wildlife conservation
Maricopa County's floodplains come in a variety of forms. The Indian Bend Wash in Scottsdale is a nationally recognized example of a natural drainage channel expanded to include a wide, greenbelt floodplain. The greenbelt offers dry weather recreational amenities such as golf courses, multi-use paths and ball fields while providing increased floodwater conveyance capabilities in wet weather. The floodplains of the county's five major river systems are especially important. Besides their natural floodwater control properties, they provide wildlife habitat, and groundwater filtering and recharge. A floodplain is a fragile environment and can lose its ability to function properly by natural changes or human alteration. Restoration efforts such as the District's El Rio vegetation control research project on the Gila River can bring a floodplain back to its original state. Non-structural management activities, such as the regulation of development in floodplains, keep floodplains clear to function as nature intended.
The Floodplain Regulations for Maricopa County define the rules for usage, development restrictions and permitting requirements necessary to protect the environmental and flood control qualities of floodplains.
The District conducts floodplain delineation studies for 100-year floodplains throughout the County. Floodplain delineation involves the development of detailed topographic maps to determine where water flows, while incorporating the results of rainfall runoff relationship studies to determine peak flood discharges and depths. Along with extensive surveying and aerial mapping, drainage factors such as slope, vegetation, soil composition and land use are also analyzed and taken into account.
The delineation studies are used by the District to better manage the floodplain, to reduce or prevent flood damage, and to maintain the natural and beneficial functions of the floodplains. The studies are also used by FEMA to update the Flood Insurance Rate Map (FIRM) for each area for the National Flood Insurance Program.
Flood Insurance Information
If your property is located in a FEMA floodplain, you are required by your lending institution to purchase flood insurance. Floodplain representatives are on hand at the District to help residents determine whether or not their property is in a flood hazard area and to provide information. There are alternatives to purchasing flood insurance. It may be possible to challenge the determination or make changes to your house or property that could move you out of the floodplain.
Floodplain Use Permits
If your property is located within a floodplain, you must also acquire a floodplain use permit to make any changes to your property. The Flood Control District enforces floodplain regulations, which regulate the location and construction of buildings and other development within designated floodplains. The District is required to ensure structures or improvements in the floodplain will not cause adverse impacts to properties upstream or downstream.
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