Water Obstructions and Encroachments - Floodway Activity Locations

A floodway is the portion of the available flow cross section (channel of a stream or any other watercourse and adjacent floodplain area) that cannot be obstructed without causing an increase of more than a foot in water-surface elevations. The Federal Emergency Management Agency has established the amount to be one foot based on floods that occur, on average, every 100 years. Floodways generally depict those areas where flooding is deeper and more severe. The designations are made in an effort to control the increase in flood heights.泄洪道（floodway）指可过流断面（河道或其他水道的槽段与相邻洪泛区）中，若对其实施封堵将导致水面高程升高超过1英尺的区域。美国联邦紧急事务管理局（Federal Emergency Management Agency）以平均每100年一遇的洪水为基准，将该临界升高值设定为1英尺。泄洪道通常对应洪水更深、灾情更为严峻的区域，划定此类区域的目的在于管控洪水水位的升高幅度。