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The District has developed software to assist the engineering community perform tasks using standard methods approved by the District. The District also offers HEC-HMS model parameterization spreadsheets to help standardize submittals to the District for review and approval. For your convenience, the software page also contains links to public domain software.

Pima County Developed Software


PC-HYDRO Version 7.2 

PC-HYDRO v. 7.x is a web interface that executes the Pima County Hydrology Procedure equations is now available. Rather than a stand-alone program installed on your local machine PC-HYDRO is available from the internet.  More information is available on the PC-HYDRO page.  PC-HYDRO is the official modeling method for hydrology to be submitted to Pima County Regional Flood Control District

Natural Resources Conservation Service Hydrologic Soils Groups Map within Pima County

The Natural Resources Conservation Service (NRCS) has updated the Hydrologic Soils Groups maps for Pima County, effective October 1, 2016, the starting date of the NRCS fiscal year. Every October 1, if any additional revisions have been adopted by the NRCS, the District will obtain the revisions and update the Hydrologic Soils Groups classifications available through our website. The 2016 revisions are now available, and the updated soils classifications should be used for all engineering analyses initiated after October 1, 2016. As annual updates are provided, some Hydrologic Soils Groups may be subject to change. The Director’s letter provides additional information.

Pima County Developed Software


PC-ROUTE v. 8.0 (Microsoft Excel format, right-click and choose "Save as" option to download), updated on 12/24/20, is a spreadsheet to perform routing calculations for a design hydrograph through a stormwater detention/retention facility with a given facility geometry and outlet configuration was developed by the District for general distribution to the consulting community. Please see the PC-ROUTE Manual  for more information.

Pima County Developed Software

Please see Technical Policy 012:  Methods to Estimate Maximum Anticipated Scour Depth Including Optional Adjustment for Flood Duration and the Local Scour Background Summary Report for more information on the use of PC-SCOUR and PC-SCOUR TR.


PC-SCOUR Version 10.0 (Microsoft Excel format, right-click and choose "Save as" option to download) is software designed to calculate maximum anticipated scour depth.  NOTE: This spreadsheet was revised in December 2017.  PC-SCOUR is a spreadsheet for calculating maximum anticipated scour depth for simple curved and straight reaches of non-regional sand bed conveyances with optional local scour at abutments and bridge piers, without local scour at drops or long term degradation.

PC-SCOUR TR (Temporal Reduction)

PC-SCOUR TR Version 2.0 (Microsoft Excel format, right-click and choose "Save as" option to download) is software designed to calculate maximum anticipated scour depth with routines for adjusting scour for the duration of flow event.  NOTE: This spreadsheet was revised in April 2015.  PC-SCOUR TR can be used instead of PC-SCOUR as a method to reduce scour depths where the flood hydrograph is short.

Pima County Developed Software


The District has developed PC-LID software (Microsoft Excel) for Water Harvesting calculations for use in Low Impact Development (LID) designs.

Pima County Developed Software

FLO-2D Pro Approved for Use in National Flood Insurance Program Applications in Pima County

The Federal Emergency Management Agency (FEMA) has notified the District that FLO-2D Pro meets the minimum requirements for use in National Flood Insurance Program (NFIP) applications in Pima County. The acceptance letter was dated October 7, 2016. Please see the Districts draft amendment to Technical Policy 033: FLO-2D Technical Guidance for Hydrologic and Hydraulic Modeling (DRAFT) for model parameterization guidance.

Pima County Developed Software

Base Flood Elevation Calculation Spreadsheet

Base Flood Elevation (BFE) Calculation Spreadsheet (Microsoft Excel format, right-click and choose "Save as" option to download).  Use this spreadsheet to calculate the Base Flood Elevation (BFE) and Regulatory Flood Elevation (RFE).  Please see Technical Procedure 101 for more information about calculating the BFE.

HEC-HMS Model Parameterization Spreadsheets

The District has developed the following spreadsheets to assist in model parameterization of HEC-HMS models. The files are in Microsoft Excel format, right-click and choose "Save as" option to download.

  • Manning's Normal Flow - This spreadsheet calculates normal flow discharge given a channel slope, water surface elevation, ground profile across the channel (Sta & Elev data pairs), and Manning's roughness coefficients corresponding to the ground profile. The water surface elevation or channel slope are varied to obtain, by trial-and-error, the desired discharge. Once this discharge is achieved, the hydraulic characteristics for critical flow conditions given this discharge flowing through the entire cross section may be calculated. A cross section plot may be printed, showing the flow elevation. Macros must be enabled for the spreadsheet to function correctly.
  • Aerial Reduction Factor and Storm Distribution - Calculate rainfall areal reduction and provide a 3-hr or 24-hr design storm distribution
  • Curve Number (CN) - Calculate Curve Number for a subbasin. The CN is not adjusted for rainfall intensity or antecedent moisture conditions. (Updated June 28, 2012)
  • Number of Routing Steps - Calculate number of routing steps for a channel using a HEC-RAS standard output table.
  • Storage Discharge - Calculate a Storage-Discharge relation for the Modified-Puls channel routing using a HEC-RAS standard output table.
  • Time of Concentration (Tc) - Calculate sum of the travel time for sheet, shallow concentrated and channel flows. The travel time for channel flow is calculated using a HEC-RAS standard output table.


Public Domain Software