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PC-Hydro Hydrologic Modeling Software

NOTE: The NOAA Atlas 14 Precipitation Frequency Data Server is available and populating in PC-HYDRO. 

If there are any errors with the NOAA Atlas 14 data server, PC-HYDRO can still function as hydrologic computation software utilizing a workaround method to account for rainfall data. Please contact for further information.

PC-HYDRO 7 is a web interface that executes the Pima County Hydrology Procedure equations.

Some key facts about PC HYDRO 7.1:

  • PC-HYDRO 7.1 has been accepted by FEMA and is approved for use in the National Flood Insurance Program applications in Pima County.
  • PC-HYDRO 7.1 is the result of a District sponsored comprehensive study of PC-HYDRO and the Pima County Hydrology Procedures.
  • The Adjusted Curve Number Correction has been removed to more accurately match the recorded gage data analyzed in the comprehensive study.
  • The comprehensive study is provided as Appendix G.

Hydrologic calculations for submittal to Pima County in accordance with Technical Policy 015, Acceptable Methods for Determining Peak Discharges, must now be performed with PC-HYDRO 7.1. Please read the Chief Engineer's memo about the version 7.1 release for more details.


NOTE:  The District will only accept output from  PC-HYDRO v. 7.x. Please read the Chief Engineer's memo about the version 7.1 release for more details.
UPDATE:  The District uploaded a new version of PC-HYDRO on District’s website. This new version incorporates a single revision to the Pima County Hydrology Procedures:
  • Removal of the Adjusted Curve Number Correction
PC-HYDRO V 7.1, a web interface of the Pima County Hydrology Procedures continues to provide:
  • Modification of the Generate Hydrograph dialog to include drop down selections in place of radio buttons
  • Time stamp on output sheets to include the date the NOAA data was retrieved and the date the calculations were performed
  • Insertion of a marker on the google-map to pinpoint the location of the utilized latitude/longitude
  • Addition of a notes field
  • Actual data for multiple return periods, rather than utilizing ratios
  • Multiple hydrologic data sheets with a single output command
  • Multiple hydrograph output in pdf, csv or excel format


NOTE:  PC-HYDRO V 7.1 will continue to utilize the *.pk6 file format. PC-HYDRO will still open *.pk5 data but will henceforth save data as a *.pk6 format.


Hydrologic Soils Group Maps

Hydrologic Soils Group data is available for use from the Pima County Geospatial Data Portal


A PimaMaps application that include the Hydrologic Soils Groups for Pima County can be found at the link below:

System Requirements

PC-HYDRO 7.x  has been tested on recent versions of all popular web browsers. It requires Javascript to be enabled within your browser in order to run. 


PCDOT&FCD, 1977 and 1979. Hydrology Manual for Engineering Design and Flood Plain Management within Pima County, Arizona. Pima County Department of Transportation and Flood Control District, Tucson, Arizona. This manual was written by Michael E. Zeller, PE.

PCDOT&FCD, 1987. Stormwater Detention/Retention Manual. Pima County Department of Transportation and Flood Control District, and the City of Tucson Department of Transportation, Tucson, Arizona.

Reporting Problems

Please report any computational or other problems with this software to Jacob Prietto at the Pima County Regional Flood Control District (520-724-4600).