HEC-HMS (Hydrologic Modeling System) 3.1.0
WRCS is an authorized vendor of the Corps of Engineers' recently released Hydrologic Modeling System (HEC-HMS) Version 3.1.0. HEC-HMS is designed to simulate the precipitation-runoff processes of dendritic watershed systems. It is the successor to HEC-1 and provides a similar variety of options but represents a significant advancement in terms of both computer science and hydrologic engineering. In addition to unit hydrograph, hydrologic and reservoir routing options, capabilities include a linear quasi-distributed runoff transform (Mod Clark) for use with gridded precipitation, continuous simulation with either a one-layer or more complex five-layer soil moisture method, and a versatile parameter estimation option. The software is designed for interactive use in a multi-tasking, multi-user network environment, and can be used with both X-Windows and Microsoft Windows.
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.
HEC-HMS provides a variety of options for simulating precipitation-runoff processes. In addition to unit hydrograph and hydrologic routing options similar to those in HEC-1, capabilities currently available include: a linear-distributed runoff transformation that can be applied with gridded (e.g., radar) rainfall data, a simple "moisture depletion" option that can be used for simulations over extended time periods, and a versatile parameter optimization option. The latest version also has capabilities for continuous soil moisture accounting and reservoir routing operations.
The primary new features include:
- New outflow results for reservoir structure
- Specified release method for reservoir routing
- Radial and vertical gates added to reservoir spillways
- New optional parameter for orifice outlet in reservoir
- New Smith-Parlange loss rate method in subbasin
- New nonlinear Boussinesq baseflow method in subbasin
- Lateral weir and pump station methods for diversion
- Optional stage calculations added to two routing methods
- Channel losses added to reach
Hardware/Operating System Requirements
Any IBM or compatible machine with an 80386 processor or higher (an 80486 or higher is recommended). A hard disk with at least 15 megabytes of free space (20 megabytes or more is recommended). A CD-ROM drive. A minimum of 16 megabytes of RAM. A mouse. Color VGA or better video display (recommend running in Super VGA or higher). MS Windows 95, or MS Windows NT version 3.51 or higher.Features
HEC-HMS is comprised of a graphical user interface (GUI), integrated hydrologic analysis components, data storage and management capabilities, and graphics and reporting facilities. The Data Storage System, HEC-DSS, is used for storage and retrieval of time series, paired-function, and gridded data, in a manner largely transparent to the user.
The Graphical User Interface (GUI) provides a means for specification of watershed components, inputting data for the components, and viewing the results. The GUI has capability for schematic representation of a network of hydrologic elements (e.g. sub-basins, routing reaches, junctions, etc.). You can configure the schematic by selecting and connecting icons that represent the elements. Once a schematic is developed, pop-up menus can be invoked from the element icons. A menu provides access to an editor for entering or editing data associated with the hydrologic element, and enables display of results of a simulation for that element. The GUI also contains global editors for entering or reviewing data of a given type (e.g., values for Green & Ampt parameters) for all applicable elements.
The results of the active run can be viewed and printed in tabular or graphical form. Three types of tabular data are available: (1) a master summary table with a single line of information for each hydrologic element, (2) an element summary table with information tailored to the element type, and (3) an element time series table that shows results for each time interval. A graphical display is also available for each element type.
Technical Capabilities
The basic framework for simulation of basin runoff is similar to that in HEC-1. You can also import data from an HEC-1 input file. Hydrologic elements are arranged in a dendritic network, and computations are performed in an upstream-to-downstream sequence. Computations are performed with SI (Systeme International d`Unites) units. However you can enter input and view output with units in the U.S. Customary system, and can readily convert input/results from one unit system to the other.The execution of a simulation, called a "run", requires specification of three sets of data. The first, labeled Basin Model, contains parameter and connectivity data for hydrologic elements. Types of element are: sub-basin, routing reach, junction, reservoir, source, sink, and diversion. The second set, labeled Precipitation Model, consists of meteorological data and information required to process it. The model may represent historical or hypothetical conditions. The third set, labeled Control Specifications, specifies time-related information for a simulation. A Project is used to hold the different data sets and can contain many of each type.
The program is multi-platform capable, meaning it operates on more than one kind of computer operating system. The CD-ROM versions contain executable files and installation instructions for Windows XP/2000/NT/98/95 systems.
Watershed Physical Description
The physical representation of a watershed is accomplished with a basin model. Hydrologic elements are connected in a dendritic network to simulate runoff processes. Available elements are: subbasin, reach, junction, reservoir, diversion, source, and sink. Computation proceeds from upstream elements in a downstream direction.
An assortment of different methods is available to simulate infiltration losses. Options for event modeling include initial constant, SCS curve number, gridded SCS curve number, exponential, and Green Ampt. The one-layer deficit constant method can be used for simple continuous modeling. The five-layer soil moisture accounting method can be used for continuous modeling of complex infiltration and evapotranspiration environments. Gridded methods are available for both the deficit constant and soil moisture accounting methods.Several methods are included for transforming excess precipitation into surface runoff. Unit hydrograph methods include the Clark, Snyder, and SCS techniques. User-specified unit hydrograph or s-graph ordinates can also be used. The modified Clark method, ModClark, is a linear quasi-distributed unit hydrograph method that can be used with gridded meteorologic data. An implementation of the kinematic wave method with multiple planes and channels is also included.
Multiple methods are included for representing baseflow contributions to subbasin outflow. The recession method gives an exponentially decreasing baseflow from a single event or multiple sequential events. The constant monthly method can work well for continuous simulation. The linear reservoir method conserves mass by routing infiltrated precipitation to the channel.
A variety of hydrologic routing methods are included for simulating flow in open channels. Routing with no attenuation can be modeled with the lag method. The traditional Muskingum method is included along with the straddle stagger method for simple approximations of attenuation. The modified Puls method can be used to model a reach as a series of cascading, level pools with a user-specified storage-discharge relationship. Channels with trapezoidal, rectangular, triangular, or circular cross sections can be modeled with the kinematic wave or Muskingum-Cunge methods. Channels with overbank areas can be modeled with the Muskingum-Cunge method and an 8-point cross section.Water impoundments can also be represented. Lakes are usually described by a user-entered storage-discharge relationship. Reservoirs can be simulated by describing the physical spillway and outlet structures. Pumps can also be included as necessary to simulate interior flood area. Control of the pumps can be linked to water depth in the collection pond and, optionally, the stage in the main channel.
Meteorology Description
Meteorologic data analysis is performed by the meteorologic model and includes precipitation, evapotranspiration, and snowmelt. Six different historical and synthetic precipitation methods are included. Two evapotranspiration methods are included at this time. Currently, only one snowmelt method is available.
Four different methods for analyzing historical precipitation are included. The user-specified hyetograph method is for precipitation data analyzed outside the program. The gage weights method uses an unlimited number of recording and non-recording gages. The Thiessen technique is one possibility for determining the weights. The inverse distance method addresses dynamic data problems. An unlimited number of recording and non-recording gages can be used to automatically proceed when missing data is encountered. The gridded precipitation method uses radar rainfall data.
Four different methods for producing synthetic precipitation are included. The frequency storm method uses statistical data to produce balanced storms with a specific exceedance probability. Sources of supporting statistical data include Technical Paper 40 and NOAA Atlas 2. While it was not specifically designed to do so, data can also be used from NOAA Atlas 14. The standard project storm method implements the regulations for precipitation when estimating the standard project flood. The SCS hypothetical storm method implements the primary precipitation distributions for design analysis using Natural Resources Conservation Service (NRCS) criteria. The user-specified hyetograph method can be used with a synthetic hyetograph resulting from analysis outside the program.
Potential evapotranspiration can be computed using monthly average values. There is also an implementation of the Priestley-Taylor method that includes a crop coefficient. A gridded version of the Priestley-Taylor method is also available.
Snowmelt can be included for tracking the accumulation and melt of a snowpack. A temperature index method is used that dynamically computes the melt rate based on current atmospheric conditions and past conditions in the snowpack.Hydrologic Simulation
The time span of a simulation is controlled by control specifications. Control specifications include a starting date and time, ending date and time, and a time interval.
A simulation run is created by combining a basin model, meteorologic model, and control specifications. Run options include a precipitation or flow ratio, capability to save all basin state information at a point in time, and ability to begin a simulation run from previously saved state information.Simulation results can be viewed from the basin map. Global and element summary tables include information on peak flow and total volume. A time-series table and graph are available for elements. Results from multiple elements and multiple simulation runs can also be viewed. All graphs and tables can be printed.
Parameter Estimation
Most parameters for methods included in subbasin and reach elements can be estimated automatically using optimization trials. Observed discharge must be available for at least one element before optimization can begin. Parameters at any element upstream of the observed flow location can be estimated. Six different objective functions are available to estimate the goodness-of-fit between the computed results and observed discharge. Two different search methods can be used to minimize the objective function. Constraints can be imposed to restrict the parameter space of the search method.
Analyzing Simulations
Analysis tools are designed to work with simulation runs to provide additional information or processing. Currently, the only tool is the depth-area analysis tool. It works with simulation runs that have a meteorologic model using the frequency storm method. Given a selection of elements, the tool automatically adjusts the storm area and generates peak flows represented by the correct storm areas.
GIS Connection
The power and speed of the program make it possible to represent watersheds with hundreds of hydrologic elements. Traditionally, these elements would be identified by inspecting a topographic map and manually identifying drainage boundaries. While this method is effective, it is prohibitively time consuming when the watershed will be represented with many elements. A geographic information system (GIS) can use elevation data and geometric algorithms to perform the same task much more quickly. A GIS companion product has been developed to aid in the creation of basin models for such projects. It is called the Geospatial Hydrologic Modeling Extension (HEC-GeoHMS) and can be used to create basin and meteorologic models for use with the program.
Documentation
The program's revised User's Manual describes how to use program features. The program's Technical Reference Manual contains descriptive information on the mathematical models used in the program. A new Applications Guide for HEC-HMS is now also available. It completes the basic documentation set for the program. All manuals are provided in PDF file format for easy online viewing and self printing.
The Technical Reference Manual is currently being updated. The current manual continues to accurately describe the simulation methods in Version 3.1.0 even though the manual was not updated with the new release. However, new simulation methods added for Version 3.0.0 are not included in the manual. The updated manual will add information to the manual on all of the new simulation methods that have been added to the program. The updated manual will also expand the amount of information for each method. The goal is to provide complete information on the source and derivation of the equations used in each method. Information will also be provided on parameter estimation. Finally, numeric solution details will be provided on how the equations are solved inside the program.
The Applications Guide is currently being updated. The current manual continues to accurately describe how to incorporate hydrologic simulation into project work. However, Version 3.0.0 includes some new features that can make the work simpler to perform. The manual also includes some screen pictures that are no longer accurate. The user should be careful to interpret the current manual in the context of interface changes made for Version 3.1.0. The updated guide will include accurate screen pictures and suggestions for better use of the program to conduct project work.
HEC-GeoHMS, Version 1.1 for ArcView
The Geo-spatial Hydrologic Modeling Extension (HEC-GeoHMS) is a software package for use with the ArcView Geographic Information System. GeoHMS uses ArcView and Spatial Analyst to develop a number of hydrologic modeling inputs. Analyzing digital terrain information, HEC-GeoHMS transforms the drainage paths and watershed boundaries into a hydrologic data structure that represents the watershed response to precipitation. In addition to the hydrologic data structure, capabilities include the development of: grid-based data for linear quasi-distributed runoff transformation (ModClark), the HEC-HMS basin model, physical watershed and stream characteristics, and background map file.
HEC-GeoHMS provides an integrated work environment with data management and customized toolkit capabilities, which includes a graphical user interface with menus, tools, and buttons. The program features terrain-preprocessing capabilities in both interactive and batch modes. Additional interactive capabilities allow users to construct a hydrologic schematic of the watershed at stream gages, hydraulic structures, and other control points. The hydrologic results from HEC-GeoHMS are then imported by the Hydrologic Modeling System, HEC-HMS, where simulation is performed.HEC-GeoHMS is now included on the HEC-HMS, HEC-Combo Pack or HEC-Works CDs (including all three Program Manuals in PDF format) at no additional cost.
Ship or Download the CD and Manuals
The HEC-HMS program is either distributed on CD or as a download. Both versions come with full program documentation in PDF file format. The CD version comes with a free copy of HEC-1 and the NEW HEC-DSS Vue program. If you want to download the program yourself you can save all shipping costs. You will be given download instructions via e-mail upon receipt of payment.PRICES:
See our Order Form for details.
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