National Streamflow Statistics Program
Contact Robert R. Holmes, Jr.
Version History
National Streamflow Statistics Program (NSS) Version 4.0b - 2008/12/08 - Added the abilities to (1) handle regression equations that have a multiple explanatory variables in the exponent term; (2) incorporate logistic regression equations that are found in some low-flow reports (ie the chance of a stream having zero flow); and (3) enable computing of area-weighted prediction intervals for sites with drainage area in more than one hydrologic region. In addition there was some cleanup in the way regression equations were presented in the output report.
New peak-flow equations have been added for Alabama, Arizona, Colorado, Florida, Louisiana, New Mexico, New York, Pennsylvania, South Carolina, and Utah, including completion of Utah Region_4. New low-flow equations have been added for Florida, Hawaii, Idaho, Montana, and Tennessee. Minor corrections were made to existing equations for Alabama, Delaware, Idaho, Illinois, Indiana, Texas, and Utah, including adding the ability to do prediction intervals for Indiana flood frequency estimates.
National Streamflow Statistics program (NSS) Version 4.0 - 2006/12/01 - Added the abilities to (1) solve regression equations for all types of streamflow statistics, not just flood-frequency statistics, (2) use region-of-influence regression for states where it is implemented, (3) compute 90-percent prediction intervals for estimates where methods for computing them are documented in reports.
National Flood Frequency program (NFF) Version 3.2 - 2004/12/14 - Updated the database to NFFv3.2_2004-12-14.mdb. Added new peak-flow equations for Connecticut and Kentucky. Corrected an error in the units displayed for conveyance in the Houston urban equations from in/hr to cubic feet per second. Corrected an error in the Wisconsin Area 1 equation for the 5-year recurrence interval.
National Streamflow Statistics program (NSS) Version 4.0 – 2006/12/01 - Added the abilities to (1) solve regression equations for all types of streamflow statistics, not just flood-frequency statistics, (2) use region-of-influence regression for states where it is implemented, (3) compute 90-percent prediction intervals for estimates where methods for computing them are documented in reports.
National Flood Frequency program (NFF) Version 3.2 - 2004/12/14 - Updated the database to NFFv3.2_2004-12-14.mdb. Added new peak-flow equations for Connecticut and Kentucky. Corrected an error in the units displayed for conveyance in the Houston urban equations from in/hr to cubic feet per second. Corrected an error in the Wisconsin Area 1 equation for the 5-year recurrence interval.
NFF Version 3.2 - 2004/09/29 - Updated the database to NFFv3.2_2004-09-29.mdb. This database contains new peak-flow equations for Alaska, Idaho, Ohio, Tennessee, Vermont, Wisconsin, and Wyoming. Along with the new database comes the ability to display 90-percent prediction intervals with the estimates for some of the updated States.
NFF Version 3.2 – 2003/04/30 - Fixed a bug in the weighting routine that occurred when equivalent years of record were missing for the regression estimates, and a bug that occurred when the drainage area for an ungaged site was in more than one region and the regions had different sets of return intervals.
NFF Version 3.1.1 - 2003/03/28 - Fixed a bug in the weighting routine that was introduced in the version 3.1 update.
NFF Version 3.1 - 2003/02/27 - Fixed a problem with solving the national urban equations that occurred when one or more of the local rural equations were missing for the region of interest. If a rural equation, such as the 5-year flow, was missing NFF would use the flow estimate for the next available recurrence interval, such as the 10-year flow, to estimate the urban flow for the missing recurrence interval. All estimates for higher recurrence intervals would also be incorrect.
NFF Version 3.0 - 2002/10/15 - Major change in converting user interface from Microsoft DOS to Microsoft Windows and converting data base from a binary file to Microsoft Access (Note: Use of trade or product names is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey). Updates or corrections to equations for
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NFF Version 2.0 - 1996/09/15 - A non-USGS release that added conversions between English and metric units.
NFF Version 1.4 - 1996/09/30 - NFF data base updated to amend incorrect values for:
- New Jersey--the constant 1 was removed from being added to the actual value entered for impervious cover, I
- New York--incorrect exponents and an incorrect regression constant were corrected for Region 6's 25-year and 500-year equations, respectively
- Wisconsin--the constant -2.3 was added to the data base to be applied automatically to the actual value entered for 2-year 24-hour rainfall, INTENS, for Areas 1, 3, and 5; incorrect exponents were corrected for Area 3's 5-, 25-, 50-, and 100-year equations
NFF Version 1.3 - 1996/02/14 - Corrected labeling of flood-frequency recurrence intervals for North Dakota. The equations developed for North Dakota are for the 2-, 10-, 15-, 25-, 50-, 100-, and 500-year recurrence intervals rather than the standard 2-, 5-, 10-, 25-, 50-, 100-, and 500-year intervals.
NFF Version 1.2 - 1995/06/02 - NFF data base updated to amend incorrect exponents in West Virginia's Region 6 equations for the 2-year and 10-year recurrence interval.
NFF Version 1.1 - 1994/11/21 - Initial release.
