Request for review of National Flood Frequency Program, Version 3 software In Reply Refer To: Mail Stop 415 February 6, 2002 OFFICE OF SURFACE WATER TECHNICAL MEMORANDUM NO. 02.04 Subject: Request for review of National Flood Frequency Program, Version 3 software The Office of Surface Water (OSW) is pleased to announce the availability of a beta version of the long-awaited revision to the National Flood Frequency Program (NFF). The NFF solves regional peak-flow frequency regression equations for every State in the Nation. The OSW has tested the basic functionality of the new NFF, but we have limited staff to test whether all 2,065 equations for 289 hydrologic regions give correct results. Because of this, we are requesting help from the Districts to check the accuracy of the equations. Specifically, we request that each District assign staff to install the new version of NFF and test the equations for each hydrologic region within your area of responsibility against regression estimates determined for the gaging stations used in the original regression analyses to determine your equations. The original version of NFF was released in 1994. Since then, the peak-flow equations have been revised for 34 States and American Samoa. The NFF web site (http://water.usgs.gov/osw/programs/nffp.html) provides a table that lists the States with new equations, the associated report numbers, and whether or not a fact sheet has been prepared to describe the new equations. Links are provided to on-line versions of the reports, when available. The fact sheets will be downloadable from the web page when NFF is released to the public. The new version of NFF incorporates the new equations, and adds the ability to weight regression equation-based estimates for an ungaged site with estimates obtained by applying the flow per unit area for an upstream or downstream gaging station to the drainage area of the ungaged site (the drainage-area ratio method). Other major changes to NFF include a new Windows graphical user interface (GUI), which replaces the original DOS interface, and a Microsoft Access data base, which replaces the original NFF-specific binary database. This Access data base will be shared with the upcoming Streamstats application for delivering streamflow statistics over the web. OSW will provide more information on Streamstats in the near future. NFF, Version 3, requires a computer running Windows 98/NT Version 4.0 or newer with service pack 5 or higher. For optimal performance, a processor running at 400 megahertz or faster with at least 64 megabytes of memory is recommended. The software can be downloaded by ftp from disftp.er.usgs.gov (18.104.22.168). After connecting to the server, change directories to /var/ftp/pub/OSW/kries, get NFFbeta7.exe and StreamStatsDB.mdb, and copy these to the Temp directory or other suitable location on your computer. To install the software double-click on NFFbeta7.exe in Windows Explorer, choose the directory in which to install the program (default is C:\Program Files\NFF) and follow the simple directions. Next, copy StreamStatsDB.mdb to the NFF program directory. The installation will put an icon on your desktop and an entry in the Programs listing accessed from your Start button. Clicking on either of these will start the program. After starting NFF, click on the Help pull-down menu at the top left of the window, then on Contents. This will cause the Help file to open. At present the help file contains the documentation from the previous version of NFF and the User's Manual for the new version. The documentation will be replaced before Version 3 is released to the public by documentation from a new Water Resources Investigations Report that is being prepared. The Users' Manual provides complete instructions for use of the new software. We ask you to test each equation that applies to your District by February 28, 2002. In addition, please assure that the applicable limits shown for each basin characteristic in the Edit Scenario window are correct. Please inform Kernell Ries (firstname.lastname@example.org, 703-648-5307) of the results of your tests, and provide him with any comments you have about the new software or the help file. Kernell is also available to answer any questions you may have on operating the program. Your assistance will help assure that we provide the best possible product to the public, and it is greatly appreciated.