The Hydrologic Modeling System (HEC-HMS) is designed to simulate the precipitation-runoff processes of dendritic drainage basins.
This includes large river basin water supply and flood hydrology, and small urban or natural watershed runoff.
Making the correct choice requires knowledge of the watershed, the goals of the hydrologic study, and engineering judgement.
The new HEC-HMS provides almost all of the same simulation capabilities, but has modernized them with advances in numerical analysis that take advantage of the significantly faster desktop computers available today.
The program is now widely used and accepted for many official purposes, such as floodway determinations[1] for the Federal Emergency Management Agency in the United States.