WMS:HEC-HMS Meteorological Model

Define meteorologic data for the model in the HMS Meteorologic Model dialog by selecting the Meteorologic Parameters menu item from the HEC-HMS menu. This dialog is used to assign precipitation data to all the basins in the model.

The HMS Meteorological Model dialog for the "Standard Project Storm" method.

Users can choose from six precipitation methods or no precipitation.

User Hyetograph

This option can be used if a hyetograph is known for each sub-basin of the watershed being modeled.

• Precipitation Data
  • Sub-Basin – Lists all subbasins in model.
  • Hyetograph – Click the button to define.
    • XY Series... – Opens the XY Series Editor
  • Total Depth (in) – Input decimal number.
  • Precip From Web – To download data from web, click the Download button.
    • Download – Opens the Get Online NOAA Atlas 14 Data dialog.

User Gage Weighting

The User Gage Weighting method allows defining one or more gages for each sub-basin in the watershed model.

• Radar Data->Rain Gages – Click to open Convert Grids dialog.
• Precipitation Data –
  • Sub-basin – Lists all subbasins in model.
  • Total Storm Gages –
    • Define... – Opens HEC Gage Weights dialog.
  • Recording Gages –
    • Define... – Opens HEC Gage Weights dialog.
  • Index Precipitation (in) –

Frequency Storm

• Precipitation Data –
  • Exceedance Probability –
  • Series Type –
  • Max Intensity Duration –
  • Storm Duration –
  • Peak Center –
  • Storm Area –
  • 5 min duration precip depth –
  • 15 min duration precip depth –
  • 1 hour duration precip depth –
  • 2 hour duration precip depth –
  • 3 hour duration precip depth –
  • 6 hour duration precip depth –
  • 12 hour duration precip depth –
  • 24 hour duration precip depth –
  • 2 day duration precip depth –
  • 4 day duration precip depth –
  • 7 day duration precip depth –
  • 10 day duration precip depth –

Standard Project Storm - Eastern US

• Precipitation Data – Method selected for precipitation simulation.
  • Index Precipitation: – Probably maximum index precipitation. Represents the total precipitation depth of the storm. Values available from HYDROMET Report 33. It can also be estimated from plates contained in EM 1110-2-1411 (US Army Corps of Engineers)
  • Storm Area: – The total drainage area at the point where the standard project flood is to be estimated.
  • Temporal Distribution: – Drop-down choices
    • Standard – Distributes the precipitation according to the criteria outlined in EM 1110-2-1411.
    • SWD – Distributes precipitation according to the Southwestern Division criteria (table 3.1 of the HEC-1 reference manual).
  • Subbasin – Column containing all subbasins included in model.
  • Transposition Factor – Can range from 0.80 to 1.40 and is multiplied by the index precipitation to determine the mean areal precipitation. The transposition factor can be determined from the SPS isohyetal pattern contained in EM 1110-2-1411 and a map of the watershed.

SCS Hypothetical Storm

• Precipitation Data –
  • Storm Selection: – Drop-down menu of choices.
    • Type I –
    • Type Ia –
    • Type II –
    • Type III –
  • Storm Depth – Decimal number in inches

No Precipitation

Select this option if no precipitation will be in the model.

Gridded Precipitation

• Precipitation Data –
  • DSS file: – Type file name or use Browse button to import file.
  • Convert ASCII or XMRG files to DSS... – Opens Convert Grids dialog.
  • Paths in DSS file: –
  • Replace missing data with zero? –
    • Yes – Toggle on if using this option.
  • Time shift in hours (UTC-local time) – Type or use arrow buttons to change time shift.