Natural and Beneficial Functions of Floodplains

Natural floodplains provide flood risk reduction benefits by slowing stormwater runoff and storing flood water. They also provide other benefits of considerable economic, social, and environmental value that are often overlooked. Floodplains frequently contain wetlands and other important ecological areas which directly affect the quality of the local environment. Some of the benefits of having floodplains function as a natural system include:

Fish and wildlife habitat protection
Natural flood and erosion control
Surface water quality maintenance
Groundwater recharge
Biological productivity
Higher quality recreational opportunities (fishing, bird watching, boating, etc.)
Education

Natural Floodplains and Flood Loss Reduction

Floodplains provide numerous flood loss reduction benefits as a result of their unique natural functions. Rivers and streams shape floodplain topography and influence riparian habitats and riverine ecosystems. Likewise, the physical characteristics of the floodplain shape flood flows and can provide flood loss reduction benefits to include the following:

Excess water storage: Floodplains provide an area which allows floodwaters to spread out and temporarily store excess water. This reduces flood peaks and velocities and the potential for erosion. One acre of floodplain flooded one foot deep holds approximately 330,000 gallons of water.
Flow rate and erosion reduction: In their natural vegetated state, floodplains slow the rate at which the incoming overland flow reaches the main water body in the area. Vegetation reduces erosion along rivers and canals and wetlands act as natural basin, holding water in naturally formed low lying areas.
Slowing runoff: A natural floodplain has surface conditions favoring local ponding and flood detention, plus subsurface conditions favoring infiltration and storage. Slowing runoff across the floodplain allows additional time for the runoff to infiltrate and recharge available groundwater aquifers.
Flow regulation during non-flood periods: During non-flood periods, groundwater discharge acts to naturally regulate the flow in a river or the level of a lake or pond. In other words, during periods of abundant water, the water can enter the groundwater system whenever there is available capacity rather than contribute to seasonal flood peaks. During low flow periods, the water flows from the higher groundwater system into lower surface waters, so that the frequency and duration of extremely low flows is reduced.

Conserving Wildlife While Reducing Flood Risk

The nation’s coastal and riverine floodplains and surrounding land areas support large and diverse populations of plants and animals by providing habitat and critical sources of energy and nutrients for these organisms. Many species spend their entire lives in the habitats found in and near to floodplains. The wide variety of plants and animals supported directly or indirectly by floodplains constitutes an extremely valuable, renewable resource important for our economic welfare, aesthetic enjoyment, and physical well-being. To find out more about possible threatened or endangered wildlife in Florida please visit; Imperiled Species Management Plan/FWC (myfwc.com) .

For more information on natural floodplain areas within the City of Oviedo, please contact Amanda Kortus, CFM at 407-971-5682.

Natural and Beneficial Functions of Floodplains