NSS Known Issues as of 2014/06/18

TABLE OF CONTENTS

General program issues
Colorado
Florida
Georgia
Illinois
Iowa
Kansas
Maine
Massachusetts
North Carolina
Ohio
Pennsylvania
South Carolina
Tennessee
Texas
Utah

General program issues

Using the "Reports" feature of the latest NSS version 6 creates reports with "NSS version 5" at the top of the report, even though version 6 is being used. Please ignore this heading.

Bank-full equations computed by NSS will only compute correctly in Imperial units. Switching to metric units will cause many of these to compute incorrectly.

Colorado

If input variables include "Percent_above_7500_ft", enter actual percentage (not percentage plus 1 as indicated in the associated report number SIR 2009_xxxx). The one will be added by NSS during its computations. Also note that prediction errors for Annual Monthly and Mean Streamflows have been corrected for Mountain, Northwest, Rio Grande, and Southwest hydrologic regions as well as Duration flows for Southwest hydrologic region.

Florida

When using the 2014-05-09 version of the NSS database, peak flow estimates for the following regions were over-estimated: Rural_Region_1_2011_5034, Rural_Region_2_2011_5034 Rural_Region_3_2011_5034, Rural_Region_4_2011_5034. NSS database versions prior to 2014-05-09 did not exhibit this error. The error was removed in the 2014-06-12 version of the database.

Georgia

For Peak_Southeast_US equations in Georgia, North Carolina, or South Carolina, the sum of all percentages entered into NSS by the user must be equal to 100% in order for the equation output to be valid. If all values report zero, the rounded input values do not equal 100%. Since NSS rounds to 3 significant figures, it is best to enter only 3 significant figures and make sure that all rounded parameters add to 100%. See report number SIR 2009-5043 (GA), SIR 2009-5158 (NC), or SIR 2009-5156 (SC) for further details. Links to these reports can be found on the NSS publications page at: http://water.usgs.gov/osw/programs/nss/pubs.html

Illinois

NSS peak flow estimates from Region_7_AMS from Illinois report number SIR_2004_5103 have been modified in NSS database version 2012-05-09 to correct typos which created inaccurate prediction intervals for the PK2, PK10, PK25, PK50, and PK500 flood estimates. While the flood estimates themselves have not changed as a result of the modifications, the prediction intervals associated with those estimates may have changed considerably. Prediction Intervals for Illinois Region 7 esimates made with versions of the NSS database prior to the 2012-05-09 version should not be used.

Iowa

When using the 2014-05-09 version of the NSS database, flow estimates for the following regions were mis-estimated: Peak_Region_3_2013_5086, Low_Flow_Northeast_Region_2012_5171, Low_Flow_Northwest_Region_2012_5171, Low_Flow_Southern_Region_2012_5171, Statewide_Flow_Duration_2012_5232. NSS database versions prior to 2014-05-09 did not exhibit this error. The error was removed in the 2014-06-12 version of the database.

Kansas

D10, D25, D50, D75, and D90 equations have been updated in NSS to subtract constant terms as outlined in SIR 2004-5032. The user no longer has to subtract these after NSS returns its output.

Maine

All non-peak-flow equations in NSS for the state of Maine produced incorrect estimates in NSS versions prior to the 2010-11-15 release. It is recommended that any work done using the non-peak equations between 2006 and November 2010 should be checked against the published equations found at: http://water.usgs.gov/osw/programs/nss/pubs.html#me

Massachusetts

The Massachusetts-Rhode Island Water Science Center strongly recommends contacting a hydrologist from their office before using any peak flow estimates generated by NSS for Massachusetts.

North Carolina

For Peak_Southeast_US equations in Georgia, North Carolina, or South Carolina, the sum of all percentages entered into NSS by the user must be equal to 100% in order for the equation output to be valid. If all values report zero, the rounded input values do not equal 100%. Since NSS rounds to 3 significant figures, it is best to enter only 3 significant figures and make sure that all rounded parameters add to 100%. See report number SIR 2009-5043 (GA), SIR 2009-5158 (NC), or SIR 2009-5156 (SC) for further details. Links to these reports can be found on the NSS publications page at: http://water.usgs.gov/osw/programs/nss/pubs.html

Ohio

When using the 2014-05-09 version of the NSS database, flow estimates for the following regions were mis-estimated: Low_Flow_LatGT_41.2_wri02_4068, Low_Flow_LatLE_41.2_wri02_4068, Peak_Flow_Full_Model. NSS database versions prior to 2014-05-09 did not exhibit this error. The error was removed in the 2014-06-12 version of the database.

Pennsylvania

When using the 2014-05-09 version of the NSS database, flow estimates for the Statewide_Flow_Duration_2012_5142 region were mis-estimated. NSS database versions prior to 2014-05-09 did not exhibit this error. The error was removed in the 2014-06-12 version of the database.

South Carolina

For Peak_Southeast_US equations in Georgia, North Carolina, or South Carolina, the sum of all percentages entered into NSS by the user must be equal to 100% in order for the equation output to be valid. If all values report zero, the rounded input values do not equal 100%. Since NSS rounds to 3 significant figures, it is best to enter only 3 significant figures and make sure that all rounded parameters add to 100%. See report number SIR 2009-5043 (GA), SIR 2009-5158 (NC), or SIR 2009-5156 (SC) for further details. Links to these reports can be found on the NSS publications page at: http://water.usgs.gov/osw/programs/nss/pubs.html

Tennessee

ROI equations for Tennessee (peak-flow and low-flow) are under construction and have been marked accordingly. Please do not use these equations until futher notice.

When using the 2014-05-09 version of the NSS database, flow estimates for the following regions were mis-estimated: Low_Flow_West_Region_2009_5159, Low_Flow_Central_and_East_Regions_2009_5159. NSS database versions prior to 2014-05-09 did not exhibit this error. The error was removed in the 2014-06-12 version of the database.

Texas

Users needing to estimate peak streamflows for Texas should consult report number SIR 2009-5087 before using NSS to solve the regional regression equations. This report provides information needed by the user to determine input values and application limits. Failure to do so may result in improper estimates. This report replaces previous peak-flow equations from WRIR 96-4307.

Utah

When using the 2014-05-09 version of the NSS database, flow estimates for the following regions were mis-estimated: Region_5, Mean_Flow_SIR08_5230_Regions_3_and_5. NSS database versions prior to 2014-05-09 did not exhibit this error. The error was removed in the 2014-06-12 version of the database.