Are Other Methods Required?

With the large set of included methods, HEC-HMS can provide information about runoff from historical or hypothetical events, with and without water control or other flood-damage reduction measures in a watershed, with fine or coarse temporal and spatial resolution, for single events or for long periods of record. But even with this flexibility, HEC-HMS will not provide all information required for all planning, designing, operating, permitting, and regulating decision making. For example, HEC-HMS does not include detailed hydraulic unsteady flow channel models, reservoir system simulation models, or flood damage models.

To meet these needs, HEC has developed a suite of software that provides additional capabilities, such as those listed in table below. This suite of software can be integrated through a common database. For example, a discharge hydrograph computed with HEC-HMS can be used directly as the upstream boundary condition for HEC-RAS (River Analysis System) or as the reservoir inflow boundary condition for HEC-ResSim (Reservoir System Simulation). Similarly, a discharge-frequency function computed with HEC-HMS (as illustrated in Flood Frequency Studies of this report) can be entered in the HEC-FDA (Flood Damage Reduction Analysis) interface and used subsequently to compute EAD.

Other HEC Software that can be used Along with HEC-HMS to Perform a Hydrologic Analysis

Software	Description of Capabilities
HEC-RAS River Analysis System	Solves open-channel flow problems and is generally used to compute stage, velocity, and water surface profiles. Computes steady-flow stage profiles, given steady flow rate, channel geometry, and energy-loss model parameters. Computes unsteady flow, given upstream hydrograph, channel geometry, and energy-loss model parameters.
HEC-FDA Flood Damage Reduction Analysis	Computes EAD, given flow or stage frequency function, flow or stage damage function, levee performance model parameters. Uses risk analysis (RA) methods described in EM 1110-2-1619 (USACE, 1996).
HEC-FIA Flood Impact Analysis	Computes post flood urban and agricultural flood damage, based upon continuous evaluation with flow or stage time series.
HEC-SSP Statistical Software Package	Performs statistical analysis of hydrologic data. Includes options for computing a Bulletin 17B (IACWD, 1982) analysis of annual peak flow as well as volume-duration data.
HEC-ResSim Reservoir System Simulation	Simulates reservoir system operation, given description of reservoirs and interconnecting channels, reservoir inflow and local flow hydrographs, and reservoir operation rules.

In the examples presented herein, the need for these other programs is identified and their role is described. However, this manual does not describe use of the programs; user's manuals and applications guides for these programs are available currently or are planned.