Flood plain: Low lands adjoining the channel of a river, stream, lake or ocean that are periodically inundated by floodwater. On major rivers, the flood plain is typically defined by geological features such as river bluffs.

Floodway: The central area of the river that carries the swiftest and deepest water during a flood.

Flood plain manager: A local official appointed to carry out provisions of the National Flood Insurance Program, such as building restrictions.

100-year-flood: A flood that has a 1 percent chance of occurring in any given year.

500-year-flood: A flood that has a 0.2 percent chance of occurring in any given year.

Levee: An earthen embankment used to protect low-lying land from flooding.

Levee district: A political subdivision formed by landowners to pay for the construction and maintenance of a levee protecting their land.

Tax-increment-financing: An economic development tool used to divert increased tax revenue from new businesses in a given area to new roads, sewers and other services in the area. Often used to rehabilitate blighted neighborhoods.

Wing dike: A structure used to divert river flows toward a single main channel.