Natural and Beneficial Functions of Floodplains (Excerpt from FEMA Publication 480)
Floodplains are complex and dynamic biological systems. When portions of floodplains are preserved in their natural state, or rehabilitated/ restored to a natural state, they provide many benefits to human and natural systems. Natural and beneficial functions tend to fall into three categories:
(i) Natural flood and erosion control
Over time, floodplains develop their own ways to naturally handle flooding and erosion using natural features that provide floodwater storage and conveyance, reduce flood water velocities and flood peaks, and reduce sedimentation. These natural controls help to maintain water quality by filtering nutrients and impurities from stormwater runoff, processing organic wastes, and moderating water temperature fluctuations. Floodplains contribute to groundwater recharge by promoting infiltration and replenishment of aquifers, and they help reduce the frequency and duration of low surface flows.
(ii) Biological resources and functions
Floodplains enhance biological productivity by supporting a high rate of plant growth and habitat for rare and endangered species. This helps to maintain biodiversity and the integrity of ecosystems. Floodplains also provide habitats for fish, waterfowl and wildlife by providing breeding and feeding grounds.
(iii) Societal benefits and functions
People benefit from floodplains through the production of wild and cultivated agricultural crops they provide, recreational experiences they offer, and scientific and outdoor educational opportunities gained by studying them. Floodplains contain cultural resources such as historic and archeological sites.
Parks, nature trails, bike paths, open spaces, and wildlife conservation areas are important to people. By transforming floodplains into value-added assets, they can help make a community more appealing to residents, potential employers and investors, and tourists, thereby improving the community’s economic status and overall quality of life.