|WORLD METEOROLOGICAL ORGANIZATION||
|Explanation of the criteria for classification and numbering of components||
|Explanation of the dates on the component's description|
HYDROLOGIC MODELLING SYSTEM (HEC-HMS)
1. Purpose and objectives
The program computes individual-event or continuous hydrographs for use
in planning and design of flood control and water conservation projects.
HEC-HMS is the U.S. Army Corps of Engineers’ new generation software for precipitation-runoff simulation and supersedes the HEC-1 Flood Hydrograph Package. HEC-HMS is a significant advancement over HEC-1 in terms of both computer science and hydrologic engineering. Streamflow from basins of any size is computed using the four processes of watershed runoff, river routing, combining at confluences, and diversions. Runoff hydrographs are computed from rainfall, loss rates (infiltration), unit hydrographs or kinematic wave, and baseflow data.
Infiltration is computed using: initial and uniform, SCS curve number,
Green & Ampt, or soil-moisture-accounting loss functions. Unit hydrographs
may be input directly as ordinates or are computed from Clark, Snyder, or
SCS synthetic methods. Baseflow decreases logarithmically from a given value
on the recession limb of an event hydrograph or is computed from soil
moisture accounting. Basin-averaged rainfall may be input directly or
computed from point rainfall data using gage weightings, standard project
or probable maximum storm criteria, or from gridded radar rainfall. Stream
Internal computations are in metric system; input and output may be in
either metric or English system.
A Graphic User Interface prompts the user for information needed. Required data are rainfall, infiltration, unit hydrograph or kinematic wave
excess transform, baseflow, channel and reservoir routing parameters, and
stream connectivity for hydrograph calculations.
Hydrographs are available in graphical, tabular, and/or electronic file format for every computation node in a river basin. A tabular summary is
available for the entire simulation. All hydrographs are written to the HEC
Data Storage System, HEC-DSS, for further use in this or other models.
5. Operational requirements and restrictions
a. Persons using the programs need to have knowledge of hydrological
6. Form of presentation
The software is available on CD or may be downloaded from www.hec.usace.army.mil. Support documentation consists of Release Notes,
User’s Manual, Technical Reference Manual, Short-Course Lecture and Workshop
Documents, and technical papers. Instructional videotapes are also available
7. Operational experience
Extensive; worldwide, with HEC-1 predecessor to this new software. ISO
9000 validation documentation is under preparation for HEC-HMS.
8. Originator and technical support
The Hydrologic Engineering Center, HEC, U.S. Army Corps of Engineers, developed the software. Technical support is provided by numerous
engineering institutions worldwide.
10. Conditions on use
The Internet download is free; a standard charge is made for supplying the CD.
| Reclassified from J20.2.01 MAR 1987
(First entered: 3 FEB 81
Last updated: 1 DEC 99)