A Natural Corridor for Water
A floodplain is a shoreline area which has been or is subject to flooding. It is a natural corridor for water which has accumulated from snow melt or from heavy rainfall in a short period. Floodplains are usually flat areas with rich soil because they have been formed by deposits from flood waters. As such they are attractive places for man to build and farm until the next flood passes across the plain. In certain areas, these plains can be flood proofed by diking or building levees along the adjacent river or stream, but always with provisions for tremendous amounts of water that will sooner or later be generated by weather conditions.
Streamway modifications can be placed in such a way to cause channelization. Channelization tends to destroy the vital and fragile floodplain shoreline habitats and increase the velocity of waters in times of extreme flow. This may cause considerable damage downstream even in areas already given some flood protection. In unprotected floodplains, land-use regulations must be applied to provide an adequate open corridor within which the effects of bank erosion, channel shifts, and increased runoff may be contained.
Obviously, structures which must be built on a floodplain should be of a design to allow the passage of water and, wherever possible, permanent vegetation should be preserved to prevent erosion, retard runoff, and contribute to the natural beauty of the floodplain.