HEC-RAS includes several quasi-unsteady boundary conditions, but only one upstream quasi-unsteady boundary type. Each upstream boundary (the upstream cross section of an open-ended upstream reach) requires a Flow Series boundary. Quasi-unsteady flow models must be dendritic, which means they will have one and only one downstream boundary. HEC-RAS includes three options for setting quasi-unsteady downstream boundary conditions: Stage Time Series, Rating Curve, or Normal Depth. Optional internal boundaries include Lateral Flow Series, Uniform Lateral Flow Series, and Time Series Gate Operations.
