'''The Standard Step Method''' (STM) is a computational technique utilized to estimate one-dimensional surface water profiles in open channels with gradually varied flow under steady state conditions. It uses a combination of the energy, momentum, and continuity equations to determine water depth with a given a friction slope <math>(S_f)</math>, channel slope <math>(S_0)</math>, channel geometry, and also a given flow rate. In practice, this technique is widely used through the computer program [[HEC-RAS]], developed by the US Army Corps of Engineers Hydrologic Engineering Center (HEC).<ref>{{cite web|last=USACE|title=HEC-RAS Version 4.1 User's Manual|publisher=Hydrologic Engineering Center, Davis, CA}}</ref>
