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HydroCAD Stormwater Modeling - Since 1986

Rainfall Tables

Rainfall Tables

Click for complete self-training materialsHydroCAD provides several options for defining the rainfall distribution to be used with the SCS or SBUH runoff procedures.

Most projects will use one of the predefined rainfall tables listed below.  The most common are the SCS/NRCS rainfalls listed at the top of the table.

With HydroCAD-10, you can also generate a synthetic rainfall distribution based on local precipitation frequency data.  Details here.

For special applications, you can create a custom rainfall table by hand.

Predefined Rainfall Tables

The following predefined rainfall distributions are included with HydroCAD-10, or available for download from this page.

Rainfall Name(s) Comments
Type I 24-hr
Type IA 24-hr
Type II 6-hr
Type II 12-hr
Type II 24-hr
Type III 6-hr
Type III 12-hr
Type III 24-hr
Standard SCS/NRCS distributions used for most projects in the United States.  Supplied as polynomial curves for optimum results over the widest range of Tc values.  The 6 and 12 hour durations were added in HydroCAD-9.1
Type I 24-hr Tabular
Type IA 24-hr Tabular
Type II 6-hr Tabular
Type II 12-hr Tabular
Type II 24-hr Tabular
Type II 48-hr Tabular
Type III 24-hr Tabular
Tabular versions of standard SCS/NRCS distributions.  Recommended only for direct TR-20 comparisons.  Available by download only.  Right-click any item and save to your HydroCAD\Rainfall folder.
Type II FL 24-hr Modified Type II storm used by Southwest Florida Water Management District and Saint Johns County, Florida.
Type IIA CS 24-hr Modified Type IIA storm for Colorado Springs, Colorado.  Added in HydroCAD 6.1
Type B 6-hr Same as the Emergency Spillway distribution (ESH), but preset to a duration of 6 hours.   Added in HydroCAD-10 build-4.
WinTR-55 (new!) 2012 WinTR-55 rainfall tables for Nevada, plus NOAA and NRCC regions A, B, C, and D.  Added in HydroCAD-10 build 11.
"Chicago Storm" This term refers to a technique for using IDF coefficients to define a mass curve.  This is illustrated in the "Sample D" rainfall table and discussed in the rainfall.txt file.
SFWMD 24-hr
SFWMD 72-hr)
Southern Florida Water Management District
FDOT 1/2/4/8/24-hr
FDOT 3/7/10-day
Florida Department of Transportation
Orange County, Florida
  6-hour  24-hour 
Use with 10, 25, or 100 year depth.
Added in HydroCAD-10 build-2.
SJRWMD 96-hr Saint John's River Water (Florida) management District 96-hour rainfall based on the SCS Type II 24-hour rainfall according to Section 14.2 of the MSSW Handbook.  Provided in half hour increments as described in MSSW, or tenth hour increments for greater accuracy and consistency with the Type II storm on which it is based.  Added in HydroCAD-10 build-2.
Spillway Emergency SCS Emergency Spillway Hydrograph (ESH, a.k.a Type B).
Spillway 1-day 10-day SCS Principal Spillway Hydrograph (PSH)
Constant Intensity Usable at any duration.  Added in HydroCAD 7.0.
Sample A (intensity curve)
Sample B (smoothed curve)
Sample C (mass curve)
Sample D ("Chicago" storm)
Fictional rainfall examples that may be used as the basis for custom storms.
Austin 3-hr Design storms for Austin, Texas, for return periods of 2, 5, 10, 25, 50, & 100 years.
Calgary 24-hr Calgary Stormwater Manual, 2000 (includes event definitions)
Added in HydroCAD-10.
Charlotte 6-hr 2-yr and 10-yr "Balanced Storms" for Charlotte, NC.
25, 50, and 100-yr storms added in HydroCAD 10 build 11.
Edmonton 4-hr and 24-hr Edmonton Design Standards, 2008 (includes event definitions)
Added in HydroCAD-10 build 8.
E-WA Short
E-WA Long Region 1-4
Eastern Washington State.  Added in HydroCAD 7.1
Fayette 5-hr 1995
Fayette 6-hr 10-yr
Fayette 6-hr 100-yr
Fayette 18-hr 1992
Lexington-Fayette, KY.  Added in HydroCAD 7.0.
 
Fayette05 6-hr 10-yr
Fayette05 6-hr 100-yr
Fayette05 24-hr 10-yr
Fayette05 24-hr 100-yr
Lexington-Fayette, KY - revised 2005 rainfalls.  Added in HydroCAD 7.1.
Fayette09 1-hr 1-yr (Lexington-
Fayette09 1-hr 10-yr
Fayette09 1-hr 100-yr
Lexington-Fayette, KY - new 2009 rainfalls.  Added in HydroCAD-10.
Huff 0-10sm
Huff 10-50sm
Huff 50-400sm
Illinois Huff distributions from ISWS Bulletin-71 & Circular-173.  Supplied for 1st, 2nd, 3rd, and 4th quartiles.
Huff B70 0-10sm Updated Illinois Huff distributions from ISWS Bulletin-70.  Supplied for 1st, 2nd, 3rd, and 4th quartiles.  Added in HydroCAD-10.
Indy Huff 24-hr Variation of the Huff distributions from Indianapolis Stormwater Manual 5/10/95.
Indy Huff Indianapolis SQU Guide 7/20/06.  1st, 2nd, 3rd, 4th quartiles.
Indy Huff South Bend Porter County Indiana, 1st, 2nd, 3rd, 4th quartiles.  Added in HydroCAD-10 build 11.
LA County DPW 24-hour
LA County DPW 96-hour
Los Angeles County DPW 2006 Hydrology Manual, using 10%+40%+35%+100% depths.  Added in HydroCAD-10.
NJ DEP 2-hr New Jersey DEP Water Quality Storm.  Added in HydroCAD 7.1
RSA 24-hr  (Type 1, 2, 3, 4) "Chicago" style rainfalls for Republic of South Africa.  Added in HydroCAD-10.  Rainfall type and depth maps: 1MB PDF
San Diego 6-hr
San Diego 24-hr
San Diego Country, CA.  Added in HydroCAD 6.1.
San Luis Obispo 24-hr
  Type U and D
  2, 10, 25, 50, and 100 year
San Luis Obispo, CA, upper and lower watersheds.  Added in HydroCAD-10.
Seattle 24-hr Seattle, Washington, Flow Control Technical Requirements Manual, November 2000.
SEWRPC-90 SE Wisconsin 90th Percentile storm. Added in HydroCAD-7.0
Shelbyville Shelbyville, IN uses standard Huff distributions, above.
Thurston 24-hr (1/2 to 100-yr) 
Thurston 24-hr 1990
Thurston 7-day 100-yr
Thurston County, Washington.

 

If you need a rainfall that is not listed here, you can create a custom rainfall table or download local rainfall data.

 

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