HEC-HMS can simulate historical or hypothetical runoff, with and without water-control measures, for individual events or continuous periods. The selected methods determine which outputs and processes are represented. Detailed hydraulic, reservoir-system, consequence, or ecological analyses may require companion software, even where HEC-HMS includes related routing, reservoir-operation, or sediment capabilities.

The table below gives selected examples of complementary HEC software. A hydrograph computed in HEC-HMS may provide a boundary condition for HEC-RAS or HEC-ResSim; frequency information may support HEC-FDA. Check data units, time intervals, locations, vertical datums where relevant, scenario assumptions, and required formats before transferring results. Shared data storage does not by itself establish that two analyses are consistent.

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

Software

Role in a combined analysis

HEC-RAS (River Analysis System)

Detailed one- and two-dimensional hydraulic analysis, including water levels, velocities, and inundation, and sediment-transport capabilities. Use where the required hydraulic representation exceeds the selected HEC-HMS method.

HEC-FDA (Flood Damage Reduction Analysis)

Combines hydrologic, hydraulic, damage, and uncertainty information for flood risk management evaluation, including expected annual damage (EAD) and project-performance metrics. EM 1110-2-1619 (USACE, 2025) provides current risk-assessment guidance.

HEC-FIA (Flood Impact Analysis)

Estimates consequences for individual flood events using hydraulic results and exposure information, including economic damage and potential life loss. Event consequences differ from an annualized risk estimate.

HEC-SSP (Statistical Software Package)

Statistical analysis of hydrologic data, including annual peak-flow frequency analysis using Bulletin 17C (England et al., 2018; version 1.1, 2019). The software also retains Bulletin 17B analysis options; their availability does not establish their applicability to a new study.

HEC-ResSim (Reservoir System Simulation)

Simulation of one or more reservoirs, operating rules, goals, and constraints for planning and operational studies. Use when the reservoir-system representation required for the decision calls for these capabilities.

HEC-EFM (Ecosystem Functions Model)

Evaluates relationships between hydrologic and hydraulic conditions and ecological responses, with spatial analysis support for ecosystem investigations.

Use the current software documentation for setup, assumptions, data requirements, and interpretation. These programs support different parts of a study; their outputs must be evaluated together against the decision information required.