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Frequency Curve Determination

short url to this page:

via Bulletin 17b "Guidelines for Determining Flood Flow Frequency"

(See also, Frequency Curve Plotter for both Bulletins 17B and 17C)

The NRCS Frequency Curve Determination spreadsheet has several advantages over other free programs developed by U.S. government. For example, the NRCS spreadsheet gives the user complete control over the graphics and also provides a button for precisely reading values from the curve. USGS gage data may be retrieved automatically via the internet.

This Microsoft Excel spreadsheet was developed by the NRCS Water Quality and Quantity Technology Development Team, has been tested, and correctly reproduces the results of examples in Bulletin 17B "Guidelines for Determining Flood Flow Frequency", revised edition, March 1982. The spreadsheet employs macros which are safe in this version at the time downloaded. The user is cautioned that proper use of the spreadsheet requires training in hydrology and statistics.

downloads     Get download help here.


-->The following files require Adobe Acrobat.

Bulletin 17C

Bulletin 17B in 3 parts:     Bulletin17B_thru_appx2.pdf   (5.4 Mb)
                                                 Bulletin17B_appx3-7.pdf  (5.8 Mb)
                                                        Bulletin17B_appx8-end.pdf   (4.9 Mb)

Bulletin 17B as one big file:     Bulletin17B.pdf   (16.1 Mb)


dan moore     (Join the user database and receive emails when new revisions are released.)

Here's a screenshot of an example frequency curve:
                                             (horizontal scroll bar at bottom)

graph of frequency curve

Here's a screenshot of the instruction page with buttons:
                                             (horizontal scroll bar at bottom)

freq curve buttons sheet


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