Floodway

Synonyms

Regulatory floodway

Definition

A floodway is defined as a man-made diversion channel that is created for the discharge of river flow during flood events, without increasing the water surface elevation more than a particular reference level, usually the 100-year flood level. For the US Federal Emergency Management Agency (FEMA), the floodplain includes also the channel of a river or another watercourse, with the adjacent portion of the floodplain being used for the discharge of flood water (FEMA, 2002).

Floodways are among the protection systems that are built to avoid the catastrophic floods that occur annually in many densely populated floodplains. A floodway includes not only the diversion channel, but also any adjacent areas of the floodplain that can carry overflow. The floodway can be delineated by dikes that are built on both sides of the adjacent overbanks and by other control structures that regulate the water flow, at both ends of the diversion channel. At the inlet...