NOAA Atlas 14, Vol 11, v2

[Weimsguy]

The Point Precipitation Frequency Estimates (available from

https://hdsc.nws.noaa.gov/hdsc/pfds/)

now have additional return intervals for 200, 500, and 1000. Any chance these will be added to the Table Lookup Storm events. Also the estimates given in the download table are slightly different than those established from the Table Lookup. I realize the table lookup is for the entire county, and PF table is for a specific location. I have attached the document downloaded from the website given above for a location just West of the City of Denton TX in Denton County.

 

[psmart]

The HydroCAD lookup tables are based on published NRCS data for Win TR-20 and Win TR-55, which includes return periods up to 100 years. We'll update this data if/when new information is published by NRCS.

In the mean time, you can easily define the extra events in HydroCAD by entering the rainfall depth(s) from NOAA. You only need to define the additional events, using the pre-defined events up to 100 years.

Another option is to define ALL of your events using the NOAA data. To do this, select "Import Events from IDF" in HydroCAD.


Peter Smart
HydroCAD Software

http://www.hydrocad.net