DES 606 : Watershed Modeling with HEC-HMS

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					      DES 606 :
Watershed Modeling with
      HEC-HMS
           Module 2
Theodore G. Cleveland, Ph.D., P.E
         29 June 2011
     Module 2: HEC-HMS
• Applications
• Overview of HEC-HMS
• Example 2 – A minimal HEC-HMS
  model.
              Applications
• HEC-HMS
  – Hydrologic model
• Peak Flows
• Hydrographs
              Applications
• Hydrograph Routing
  – Stream reaches
  – Reservoirs and detention basins
  – Hydrograph lagging and attenuation
  – Sub-basin modeling (if appropriate)
         Modeling Principles
“ … models are like maps; never final, never
  complete until they grow as large and
  complex as the reality they are supposed
  to represent.”
  Paraphrased from James Gleick
  “Genius: The Life and Science of Richard Feynman”
         Modeling Principles
A model is a simplification of reality – should
  capture the excitation-response of the
  system under study but only as complex
  as needed.
          Hydrologic Models
• Require engineering judgment
  – Experience helps
  – Results can be difficult to interpret
• Require accurate input data
  – Judgment here too, some data have marginal
    influence on results, other data are vital.
• Require quality control procedures
HEC-1 (Predecessor to HEC-HMS)
• Separate (individual) programs in 1967 (L.
  R. Beard)
• Unified into a single program in 1973
• Revised in 1981: kinematic wave
• PC full version in 1988
• Revised 1991: Extended memory support
• Final release 1998
  – 32 years development until final release
                 HEC-HMS
•   Evolved from HEC-1
•   Project begun in 1990
•   HEC-HMS “released” in 1998
•   Current version is 3.5
    – 21 years of development to date.
    – Include the HEC-1 period and have nearly 50
      years of development – The program “engine”
      is mature!
                 HEC-HMS
• Purpose
  – Replacement for HEC-1
    • Foundation for future hydrologic software
  – Improved interface (GUI), graphics, and
    reporting.
  – Newer hydrologic computation methods
    imbedded
  – Integration of hydrologic capabilities
               Rainfall-Runoff Process
                                       •   Precipitation
                                            – Meterology, Climate




                                                       • Watershed
                                                           –   Losses
                                                           –   Transformation
                                                           –   Storage
•   Runoff                                                 –   Routing
     – Fraction of precipitation
       signal remaining after losses
                             HEC-HMS
    • Hydrologic Cycle Components in HEC-
      HMS (circa 2008)

                                        Evapo-                       Snowfall
                    Rainfall, P(t)
                                        transpiration
                                                              Snowpack

                                                                     Snowmelt
Infiltration Loss                    Land Surface and Vegetation
                                       Runoff               Runoff
Percolation Loss               Channels                      Reservoirs



                                                Discharge, Q(t)
                  HEC-HMS
• Precipitation
• Abstractions
  – Fraction of precipitation that does not
    contribute to runoff (and ultimately discharge)
• Routing
  – Watershed routing
  – Stream (Channel) routing
  – Reservoir (Storage) routing
                HEC-HMS
• Data management
  – Graphical User Interface (GUI)
  – Multiple input files
  – Multiple output files
  – Time-series in HEC-DSS
• All files arranged in a “Project”
  – Paths to individual files
  – Can e-mail entire project folders and have
    them run elsewhere
         HEC-HMS, IO Files
• project-name.hms
  – List of models, descriptions, project default
    methods
• basin-model-name.basin
  – Basin model data, including connectivity
• meterologic-model-name.met
  – Meterologic model data
         HEC-HMS, IO Files
• control-specifications-name.control
  – Control specifications
• run-name.log
  – Run log; messages, warnings, etc. during a
    run.
• project-name.run
  – List of runs, includes recent execution time.
                HEC-HMS
• Example 2 – A minimal HEC-HMS model
  – Ash Creek Watershed
  – Use TxDOT research reports to generate
    certain data elements
  – Illustrate the data requirements and data entry
    for a minimal HEC-HMS model
  – Illustrate the conceptual similarity to the
    rainfall-funoff diagram and the HEC-HMS file
    names.
               Summary
• HEC-HMS is a computer program for
  rainfall-runoff modeling
• A minimal model is a non-trivial exercise,
  requires considerable thought to generate
  data.

				
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posted:12/12/2011
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