ABSTRACT
The geohydraulic zones are used to define the river processes and the landuses that can be supported in each zone. Management guidelines oriented to sustaining the equilibirum of natural processes in the river as an entire system are proposed. In western Oregon and Washington, steep mountain streams descend into populated lowlands and empty into tidewaters or major rivers. Review of the present river-control practices shows that flood protection works built to modify the river processes are not reducing flood damage. The boulder zone is typified by nongraded mountain rivers with coarse bouldery sediment. Rivers discharging into tidal water produce branching channels in tidal marshes. Integral to present local and national codes is the concept that a river can be viewed as a fixed-location ditch, in which the floodway is determined only by hydraulic measures, without consideration of sediment transport in meandering equilibirum channels.
