One-Dimensional Analysis – A steady state or standard step model, meaning that there is no direct modeling of the hydraulic effect of cross section shape changes, bends, and other two- and three-dimensional aspects of flow. HEC-1, WSPRO, and HEC-RAS are examples of a one-dimensional analysis models.

Two-Dimensional Analysis – A spatially distributed hydraulic model which models dynamic unsteady flow and is therefore capable of delivering results far more accurately and closer to real life than a steady state model. Dynamic models allow the effects of storage and backwater in conduits and floodplains and the timing of the hydrographs to yield a true representation of the HGL at any point in space and time. Two-dimensional analysis models require such a high level of expertise and time to run effectively that they are used for unusual situations.