The Hydrologic Modeling System (HEC-HMS) is designed
to simulate the precipitation-runoff processes of
dendritic watershed systems. It is designed to be
applicable in a wide range of geographic areas for
solving the widest possible range of problems.
This includes large river basin water supply and flood
hydrology, and small urban or natural watershed
runoff. Hydrographs produced by the program are
used directly or in conjunction with other software for
studies of water availability, urban drainage, flow
forecasting, future urbanization impact, reservoir
spillway design, flood damage reduction, floodplain
regulation, and systems operation.
The program features a completely integrated work environment including a database, data entry utilities, computation engine, and results reporting tools. A graphical user interface allows the user seamless movement between the different parts of the program. Program functionality and appearance are the same across all supported platforms.
This model is public domain and can be downloaded for FREE using this link.
See also the Watershed Modeling System
WMS provides a high qaulity graphical user interface for HEC-HMS.
WMS performs automated basin delineation from digital elevation data and determines basin parameters needed for HEC-HMS.
WMS automatically generates HEC-HMS basin files, or your can run the full featured HEC-1 (the predecessor to HEC-HMS) fully within WMS.