U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2007–3081

September 2007 Printed on recycled paper

The U.S. Geological Survey (USGS) provides streamflow 

and other stream-related information needed to protect people 

and property from floods, to plan and manage water resources, 

and to protect water quality in the streams. Streamflow statistics provided by the USGS, such as the 100-year flood and the 

7-day 10-year low flow, frequently are used by engineers, land 

managers, biologists, and many others to help guide decisions 

in their everyday work. In addition to streamflow statistics, 

resource managers often need to know the physical and climatic 

characteristics (basin characteristics) of the drainage basins for 

locations of interest to help them understand the mechanisms 

that control water availability and water quality at these locations.

Users of stream information may require streamflow 

statistics and basin characteristics at any location along a 

stream. The USGS periodically calculates and publishes 

streamflow statistics and basin characteristics for streamflow 

data-collection sites such as gages and partial-record stations, 

but these data commonly are scattered among many reports 

that may not be readily available 

to the public. The USGS provides 

and periodically updates regional 

analyses of streamflow statistics 

which include regression equations 

and other prediction methods for 

estimating statistics for ungaged and 

unregulated streams across the State 

of Tennessee. Use of these prediction 

methods for a site can be complex 

and require the user to determine a 

number of basin characteristics that 

may require interpretation. The basin 

characteristics may include drainage 

area, classifiers for physical properties, climatic characteristics, and 

other inputs. Obtaining these input 

values for gaged and ungaged sites 

has traditionally been time consuming, subjective, and sometimes leads 

to inconsistent results.

StreamStats is a Web-enabled 

geographic information system (GIS) 

application that makes it easy for users 

to obtain streamflow statistics, basin 

characteristics, and other information 

for USGS data-collection stations and 

for ungaged sites of interest. If a user 

selects the location of a data-collection station, StreamStats will 

provide previously published information for the station from a 

database. If a user selects a location where no data are available 

(an ungaged site), StreamStats will run a GIS program to delineate a drainage basin boundary, measure basin characteristics, and 

estimate streamflow statistics based on USGS streamflow prediction methods. A user can download a GIS feature class of the 

drainage basin boundary with attributes including the measured 

basin characteristics and streamflow estimates.

StreamStats consists of five major components: (1) a user 

interface (fig. 1) that displays maps and streamflow statistics 

based on user-selected stream locations, (2) a database containing available streamflow statistics and descriptive information 

for USGS data-collection stations, (3) a GIS database that 

stores base-map data needed for users to locate sites and stores 

other map data needed for determining basin characteristics, 

(4) an automated GIS process that determines drainage-basin 

boundaries for user-selected ungaged sites and determines basin 

Tennessee StreamStats: A Web-Enabled Geographic 

Information System Application for Automating the

Retrieval and Calculation of Streamflow Statistics

By David E. Ladd and George S. Law

Figure 1. View of the Tennessee StreamStats user interface.
characteristics for those sites (fig. 2), and (5) an automated process that uses USGS streamflow prediction methods to estimate 

various streamflow statistics for gaged and ungaged sites based 

on basin characteristics (fig. 2).

StreamStats was designed for national implementation. 

However, since each State has its own unique streamflow 

prediction methods, separate applications are established for 

each State that implements StreamStats. Tennessee StreamStats provides stream-related information quickly and reliably 

without requiring users to have large investments in computer 

hardware and software and without requiring advanced knowledge of computer science, geographic analysis, or hydrology. 

The application is intended to substantially reduce the effort and 

subjectivity involved in the calculation of streamflow statistics 

by the many different users across the State. The StreamStats 

application was developed cooperatively by the USGS and the 

Environmental Systems Research Institute, Inc. (ESRI). The 

development of StreamStats for Tennessee is a cooperative 

effort of the USGS and the Tennessee Departments of Environment and Conservation (TDEC) and Transportation (TDOT). 

Figure 2. Basin delineation, partial streamflow statistics report, and basin characteristics report for 

an ungaged site using Tennessee StreamStats.

Additional Information

For further information about Tennessee StreamStats, please contact::

W. Scott Gain, Director, USGS Tennessee Water Science Center

640 Grassmere Park, Suite 100

Nashville, Tennessee 37211

(615) 837-4701

wsgain@usgs.gov

or visit:

The USGS Office of Surface Water StreamStats homepage at:

http://streamstats.usgs.gov/ or http://water.usgs.gov/osw/streamstats/

The Tennessee StreamStats homepage at:

http://water.usgs.gov/osw/streamstats/tennessee.html

The USGS Tennessee Water Science Center homepage at:

http://tn.water.usgs.gov/

Some of the information in this document was obtained from StreamStats: A 

U.S. Geological Survey Web Application for Stream Information: U.S. Geological Survey Fact Sheet FS-2004-3115, by K.G. Ries III, P.A. Steeves, J.D. Coles, 

A.H. Rea, and D.W. Stewart.

Any use of trade, product, or firm names is for descriptive purposes only and 

does not imply endorsement by the U.S. Government.

Although this report is in the public domain, permission must be secured from 

the individual copyright owners to reproduce any copyrighted materials contained within this report.

U.S. Department of the Interior

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director