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 is a generalized modeling system capable of representing many different watersheds. A model of the watershed is constructed by separating the hydrologic cycle into manageable
pieces and constructing boundaries around the watershed of interest. Any mass or energy flux in the cycle can then be represented with a mathematical model. In most cases, several model
choices are available for representing each flux. Each mathematical model included in the program is suitable in different environments and under different conditions. Making the correct
choice requires knowledge of the watershed, the goals of the hydrologic study, and engineering judgment.
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 seamless movement between the different parts of the program. Program functionality and appearance are the same across all supported platforms.