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PC-Hydro Hydrologic Modeling Software

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 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:  To accommodate existing work, the District will continue to accept output from PC-HYDRO V 6.1 until May 1, 2019. Thereafter, 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 maps are available for download from the ftpgis.pima.gov FTP server in the /pub/rfcd/pchydro/HydrologicSoilsGroupMaps/ area. The README.txt file in this directory explains the file naming convention of the soils map.

PimaMaps and MapGuide

PimaMaps and MapGuide applications that include the Hydrologic Soils Groups for Pima County can be found at the links 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 Janice Hughes at the Pima County Regional Flood Control District (520-724-4600).