What is the core regulatory intent behind designating a 'floodway' within a floodplain, beyond simply restricting development?

A 'floodway' is the channel of a river or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation by more than a designated height, typically zero net rise or a maximum of one foot. The 'base flood' is a flood event with a one percent chance of being equaled or exceeded in any given year, often referred to as the 100-year flood. This floodway is a specific, often narrower, component of the broader 'floodplain,' which is the land area susceptible to being inundated by floodwaters from the base flood. The portion of the floodplain outside the floodway is called the 'flood fringe,' w....