The intent of this manual is to present guidelines and sufficient input data for computing design hydrology in Ventura County. The methods should be used for projects subject to Ventura County Watershed Protection District (District) requirements. Input data and design procedures are intended to be sufficiently flexible that the methods can be adopted for use by all agencies and engineering consultants engaged in the design of flood control works throughout the county. The methods can be used on all small, intermediate, and large size watersheds under various conditions of development. The methods are used in computer programs such as the District’s VCRat program, the U.S. Army Corps of Engineers (USACE) HEC-HMS program, the Environmental Protection Agency’s (EPA) Hydrologic Simulation Program – FORTRAN (HSPF) model, and the USACE HEC-SSP implementation of the Bulletin 17B method for flood flow frequency analyses

2017 Design Hydrology Manual and VCRat2.64 Now Available!

PROGRAM WARNINGS!
1) Some  64-bit Windows 10 computers are preventing the VCRat2.64 Install Package from creating the required c:\VCRatWorkspace folder. If the install package does not create this folder, the program will not run. You have to create the folder (case sensitive) so that the program will run.

2) If you have tried to install the VCRat2.6 program on your 64-bit computer, you must uninstall that program before installing the 2.64 program.

3) Windows 10 Computers require that you have Administrator privileges to change the options in the VCRat2.64 program to use J Zone rainfall or mix storm types in a single model run. The alternatives for providing this capability on your computer are provided in a memo (Download Memo).

Open 2017 Hydrology Manual (24 mb, pdf) (Appendix E files provided below)

Download 2017 Hydrology Manual (24 mb, zip)

Download 2018 VCRat2.64 Zip Package

Download Updated 2021 Tc Calculator Zip Package (Installation instructions in ReadMe file in Zip Package)

Open Public Viewer for 2017 NOAA Rain Zone Map- 31 Zones, 10-, 25-, 50-, and 100-yr Rainfall Contours – and 2005 LiDAR Data

Open 2017 VCRat2.64 and Spreadsheet User Manual

Read How to Use Shapefiles in AutoCAD Civil 3D or Map 3D

Questions? Email: HydroData@ventura.org

Updated Manual Includes:

• -Revised Rainfall Zones using NOAA 2011 Design Intensity Data
• -Updated C Coefficients
• -VCRat2.64 Program to run on 64-bit machines with Windows 7 and 10
• -VCRat2.64 can use revised rainfall and C coefficients or legacy rainfall and C coefficients
• -Tc Calculator Excel Spreadsheet (Appendix E-27)
• -VCRat Single Subarea Runoff and Detention Basin Routing Excel Spreadsheet (Appendix E-28)

Coming Soon:

Updated Tc Calculator program to use revised NOAA rainfall zones.

2017 Hydrology Manual Appendix E Files

E-1       10-Yr Rainfall PDF Map (pdf 14mb,download)

E-2       25-Yr Rainfall PDF Map (pdf, 14mb,download)

E-3       50-Yr Rainfall PDF Map (pdf, 14mb,download)

E-4       100-Yr Rainfall PDF Map (pdf, 14mb,download)

E-5       10-Yr Rainfall Shapefiles NAD83 (zip,download)

E-6       25-Yr Rainfall Shapefiles NAD83 (zip,download)

E-7       50-Yr Rainfall Shapefiles NAD83 (zip,download)

E-8       100-Yr Rainfall Shapefiles NAD83 (zip,download)

E-9       NOAA Rain Zones Map and Shapefiles NAD83 (zip,download)

E-10     Updated Soils Map Shapefiles (zip,download)

E-11     Example VCRat2.64, 2.6, and 2.2 Files (zip,download)

E-12     Design Rainfall Frequency and Hyetograph Files (zip,download)

E-13     HEC-HMS Design Storm Model Input files (zip,download)

E-14     Hydrograph Transformation Spreadsheets (zip,download)

E-15     Permit Report Submittal Example (zip,download)

E-16     Tc Example Files (zip,download)

E-17     Flow-Through Basin Design Spreadsheet (zip,download)

E-18     Flow-Through Basin Model Files (zip,download)

E-19     Small Area Basin Design Spreadsheet (zip,download)

E-20     Example AR Files- VCRat2.2 and 2.64 (zip,download)

E-21     VCRAIN.DAT Files for VCRat (zip,download)

E-22     Yield Adjustment Example Files (zip,download)

E-23     Multiple Areal Reduction Factor Files for VCRat2.2 (zip,download)

E-24     Bypass Basin VCRat2.6 Files (zip,download)

E-25     Small Area Hydrograph files (zip,download)

E-26     VCRat 2.64V030 Programs (zip,download)

E-27     Tc Calculator Spreadsheet (xlsx,download)

E-28     VCRat and Basin Routing Spreadsheet (xlsx,download)

E-29     Bulked Flow Spreadsheet (xlsx,download)

NEW!   VCWPD Flood Zone Map (jpg,download)

Tc Calculator Training Materials

Download these updated Tc Calculator Spreadsheet and VCRat2.64 training materials for the updated 2017 Hydrology Manual.

Download these Tc Calculator and VCRat2.6 training materials from the 2009 training class (2010 Hydrology Manual).

2010 Design Hydrology Manual and VCRat2.6

The 2010 Design Hydrology Manual has been superseded by the 2017 Manual. VCRat2.6 for 32-bit computers has been superseded by VCRat2.64 for 64-bit computers. The VCRat2.6 methods contained in VCRat2.64 have been accepted by FEMA as a Locally-Accepted Hydrology Model that can be used to provide hydrology for FEMA studies in Ventura County.