Computer applications for step-backwater and floodway analyses

A computer program which can be used to computer water-surface profiles for gradually varied, subcritical flow is described. Profiles are computed by the standard step-backwater method. Water-surface profiles may be obtained for both existing stream conditions and for stream conditions as modified by encroachment. The user may specify encroachment patterns in order to establish floodway limits for land-use management alternatives, or for flood-insurance studies. Applicable theories, computer solution methods, data requirements, and input data preparation are discussed in detail. Examples are presented to illustrate the computer output and potential program applications. (Woodard-USGS)