floodway

[ fluhd-wey ]
/ ˈflʌdˌweɪ /

noun

the channel and adjacent shore areas under water during a flood, especially as determined for a flood of a given height.

Origin of floodway

First recorded in 1885–90; flood + way1

Scientific definitions for floodway

floodway
[ flŭdwā′ ]

A channel for an overflow of water caused by flooding.