Tennessee StreamStats

The reports below document the regression equations available in StreamStats for Tennessee, the methods used to develop the equations and to measure the basin characteristics used in the equations, and the errors associated with the estimates obtained from the equations. Users should familiarize themselves with this report before using StreamStats to obtain estimates of streamflow statistics for ungaged sites.

• Ladd, D.E., and Law, G.S., 2007, Tennessee StreamStats: A Web-Enabled Geographic Information System Application for Automating the Retrieval and Calculation of Streamflow Statistics: U.S. Geological Survey Fact Sheet 2007-3081, 2 p.
• Law, G.S. and Tasker, G.D., 2003, Flood-frequency prediction methods for unregulated streams of Tennessee, 2000: U.S. Geological Survey Scientific Investigations Report 03-4176, 79 p.
• Law, G.S., Tasker, G.D., and Ladd, D.E., 2009, Streamflow-characteristic estimation methods for unregulated streams of Tennessee: U.S. Geological Survey Scientific Investigations Report 2009-5159, 212 p., 1 pl.

Click on this link to obtain general information on the Tennessee application, as well as specific sources and computation methods for basin characteristics. 

NOTE: The Law and others (2009) report contains equations for estimating the 7-day, 10-year and 30-day, 5-year low flows, the mean annual flow, the mean summer streamflow (June through August), and flows exceeded 99.5, 99, 98, 95, 90, 80, 70, 60, 50, 40, 30, 20, and 10 percent of the time. This report also contained Region-Of-Influence (ROI) methods for estimating the same statistics. The ROI methods have not yet been included in StreamStats.
A stand-alone computer program is available to estimate the flow statistics from the Law and others (2009) report using both the conventional regression equations as well as the ROI method. This computer program requires manual entry of the basin characteristics for ungaged sites to obtain estimates of the flow statistics. All of the basin characteristics needed to solve the new equations can be obtained from StreamStats. An advantage of using this program is that it computes the probability of zero flow for the low-flow equations and then outputs zero if the probability is greater than a threshold. StreamStats can be used to obtain the basin characteristics for sites of interest, and the stand-alone program can be run to get estimates of the flow statistics. The new report and the stand-alone program can be downloaded by clicking on the embedded link in the citation above. Users should note that there are some differences in the naming of the basin characteristics between StreamStats and the stand-alone program. The geology factor needed in the stand-alone program is named the streamflow-recession index in StreamStats. Also, the soil factor needed in the stand-alone program is named the percent area underlain by soil permeability of at least 2 in/hr in StreamStats.