F.2.3.3
The Standard Step backwater method is a variation of the Direct Step backwater method and may be used to compute backwater profiles on both prismatic and non-prismatic channels. In this method, stations are established along the channel where cross‑section data is known or has been determined through field survey. The computation is carried out in steps from station to station rather than throughout a given channel reach as is done in the Direct Step backwater method. As a result, the analysis involves significantly more trial‑and‑error calculation in order to determine the flow depth at each station.
Computer Applications
There are a number of commercial software programs for use on personal computers that use variations of the Standard Step backwater method for determining water surface profiles. The most common and widely accepted programs include HEC‑RAS, published and supported by the United States (US) Army Corps of Engineers Hydraulic Engineering Center, and SWMM, originally published by US Environmental Protection Agency.