The SCS Rainfall Method was developed by the United States Department of Agriculture - Natural Resources Conservation Service (USDA-NRCS). It generated four synthetic 24-hour rainfall distribution curves that cover all geographical regions of the United States. These curves are described in Appendix B of Technical Release 55.

Use the controls described below to generate SCS rainfall to be run by the analysis.

Generate SCS Data

This link directs users to the National Weather Service website: http://hdsc.nws.noaa.gov/hdsc/pfds/.  Users can look up the appropriate rainfall details for their area if they are not already know or locally specified. 

ARI Events Spreadsheet:

ARI (Years)

A range of typical Annual Recurrence Intervals (ARI) listed for the SCS method.

Note: The WQe option is a 3 month Water Quality Event.

Use

Check the ARIs to be solved during the Analysis

Depth

Cumulative depth multiplier to the SCS hyetograph distribution - discussed below.

Run Time

Simulation run time, by default this is twice the hyetograph duration (24hours for standard SCS hyetograph).

Distribution

SCS hyetograph distributions Type 1, 1A, 2 and 3 are available by default.  If an SCS hyetograph other than these is desired it is recommended to use the Design Storm (User Defined) option.