PUBLICATIONS -- Transmittal of the report "Summary of the nationwide analysis of the cost effectiveness of the U.S. Geological Survey stream-gaging program (1983-88)" by W. O. Thomas, Jr. and K. L. Wahl


In Reply Refer To:                              October 18, 1994
Mail Stop 415


OFFICE OF SURFACE WATER TECHNICAL MEMORANDUM NO. 94.08

Subject:  PUBLICATIONS -- Transmittal of the report "Summary of 
          the nationwide analysis of the cost effectiveness of the 
          U.S. Geological Survey stream-gaging program (1983-88)" 
          by W. O. Thomas, Jr. and K. L. Wahl

The subject report summarizes a nationwide analysis of the cost 
effectiveness of the stream-gaging program that was operated by 
the U.S. Geological Survey (USGS) during 1983-88.  The subject 
report should be of interest to those individuals who operate and 
manage the USGS stream-gaging program.  

The objective of the nationwide study was to define and document 
the most cost-effective methods of furnishing streamflow 
information.  The study involved three phases:  (1) an analysis of 
the data uses and availability and documentation of the sources of 
funding for each streamflow station; (2) an evaluation of the 
utility of using less costly alternative methods, such as 
hydrologic flow routing models and statistical methods, to provide 
the needed streamflow information; and (3) an analysis of the 
cost-effective operation of the stream-gaging program that relates 
the accuracy of the streamflow records to various operating 
budgets.  A prototype study for the nationwide analysis was 
described by Fontaine and others (1984).  Statewide analyses were 
performed by hydrologists in District offices throughout the Water 
Resources Division (WRD).  The reports describing the analyses for 
the individual States are summarized and referenced in the subject 
report.

The nationwide analysis documented that (1) multiple uses were 
being made of data collected at stations in the USGS stream-gaging 
program, (2) simulated flows from hydrologic flow routing models 
and statistical methods were not generally of sufficient accuracy 
for most uses, and (3) the stream-gaging program was being 
operated in an efficient and cost-effective manner.  The cost-
effectiveness techniques developed in this study provide an 
objective way to compare the relative accuracy of streamflow 
records at several locations as a function of the number of visits 
to the station.  

The USGS has a long history of analyzing and evaluating the 
stream-gaging program.  The subject report describes the third 
nationwide analysis of the USGS stream-gaging program.  A brief 
history of surface-water network analysis within USGS follows.

The first known nationwide review of the stream-gaging program was 
conducted in 1953-58.  The purpose of the review was to design a 
hydrologic network of stream-gaging stations in accordance with 
principles described by Langbein (1954).  During this review, 
stations were classified as either water management or hydrologic 
network (regional hydrology).  Within the hydrologic network, the 
concept of primary and secondary stations was developed.  The 
primary stations were for obtaining a long-term sampling of 
streamflow and the secondary stations, operated for 5-10 years, 
were for obtaining geographic coverage of streamflow 
characteristics.  Estimation of long-term statistics at the 
secondary stations was based on correlation of monthly flows with 
the long-term primary stations.  Recommendations for improving the 
stream-gaging program are summarized in a June 1958 Administration 
Report entitled "Progress Report to Chief, Surface Water Branch on 
the Nationwide Review of Stream-Gaging Program".

The second national study of the streamflow data-collection 
program was conducted in 1969-70.  The general procedures for 
evaluating the available data, codifying the purposes of stream 
gaging and determining the desirable program of the future were 
described by Carter and Benson (1969).  The stations were 
classified by data uses as current use (water management), 
planning and design (regional hydrology), long-term trends and 
stream environment.  Within planning and design, unregulated minor 
and principal streams (over 500 square miles) were identified.  
The goals of the study were to obtain 25 years of record at 
stations on principal streams and obtain 25 years of equivalent 
record at points intermediate to gaging stations.  The goal for 
minor streams was to obtain 10 years of equivalent record through 
the use of regression equations that related a variety of 
streamflow characteristics to watershed and climatic character-
istics.  The regression equations developed in this study and the 
results of the program analysis are described in a series of 
statewide reports entitled "A Proposed Streamflow Program for 
[State Name]."  A summary of the nationwide study, including 
recommendations for improving the program, is provided by Benson 
and Carter (1973).  

As an outgrowth of the 1969-70 nationwide analysis, a new network 
analysis technique, regression analysis simulation, was developed 
by Moss and Karlinger (1974).  Ordinary least squares regression 
equations, relating streamflow characteristics to watershed and 
climatic characteristics, were used to evaluate the time-sampling 
and spatial-sampling errors in order to design a more optimal 
regional-hydrology network.  These techniques, known as Network 
Analysis for Regional Information (NARI), are described by Moss 
and others (1982).  The NARI techniques were used to determine a 
more appropriate stream-gaging strategy for reducing the standard 
error of the regional regression equations.  This strategy may 
involve operating the existing stations longer, adding new 
stations to the network or some combination of both.  The results 
of applying these techniques are described in several statewide 
reports.

The nationwide cost effectiveness analysis described in the 
subject report was conducted during the mid-1980's (Thomas and 
Wahl, 1993).  The recent emphasis on surface-water network 
analysis within the WRD is the use of Generalized Least Squares 
(GLS) regression analysis to analyze the regional-hydrology 
network.  The GLS procedures build on the techniques described by 
Moss and others (1982) by utilizing GLS regression procedures that 
incorporate the time-sampling error in streamflow characteristics 
and an improved measure of the correlation in streamflow 
characteristics between stations.  The objective is the same as in 
NARI and that is to determine if the existing stations should be 
operated longer, whether new stations should be installed or some 
combination of both.  More details on applying these procedures 
are given in Office of Surface Water Technical Memorandum
No. 87.08.  The technical aspects of the GLS procedures are 
described by Tasker and Stedinger (1989) and an example of 
applying these techniques to a surface-water data network in 
Kansas is described by Medina (1987).  

Network analysis techniques have evolved over the years from
(1) correlation of monthly mean flows as recommended by Langbein 
(1954), to (2) the use of regional regression equations to 
determine the equivalent years of record of estimated streamflow 
characteristics at ungaged sites, to (3) the use of regional 
regression equations to evaluate the trade-off between time- 
sampling and spatial-sampling errors in the design of a regional 
hydrology network.  Network analyses and program evaluation will 
continue to play a prominent role in the management of the USGS 
stream-gaging program.  Future directions will likely involve the 
development of techniques for a more coordinated analysis of 
water-quality, ground-water and streamflow networks.


References

Benson, M. A. and Carter, R. W., 1973, A national study of the 
    streamflow data-collection program:  U.S. Geological Survey
    Water-Supply Paper 2028, 44 p.

Carter, R. W. and Benson, M. A., 1969, Concepts for the design of 
    stream-flow data programs:  U.S. Geological Survey open-file 
    report, 20 p.

Fontaine, R. A., Moss, M. E., Smath, J. A., and Thomas, W. O., 
    Jr., 1984, Cost effectiveness of the stream-gaging program in 
    Maine - A prototype for nationwide implementation:  U.S. 
    Geological Survey Water-Supply 2244, 39 p.

Langbein, W. B., 1954, Stream gaging networks:  International 
    Association of Hydrological Sciences (IAHS) Publication No. 
    38, pp. 293-303.

Medina, K. D., 1987, Analysis of surface-water data network in 
    Kansas for effectiveness in providing regional streamflow 
    information [with a section on Theory and Application of 
    Generalized Least Squares by G. D. Tasker]:  U.S. Geological 
    Survey Water-Supply Paper 2303, 28 p.

Moss, M. E. and Karlinger, M. R., 1974, Surface water network 
    design by regression analysis simulation:  Water Resources 
    Research, vol. 10, no. 3., pp. 427-433.

Moss, M. E., Gilroy, E. J., Tasker, G. D., and Karlinger, M. R., 
    1982, Design of surface-water data networks for regional 
    information:  U.S. Geological Survey Water-Supply Paper 2178, 
    33 p.

Tasker, G. D. and Stedinger, J. R., 1989, An operational GLS model 
    for hydrologic regression:  Journal of Hydrology, 111, pp. 
    361-375.

Thomas, W. O., Jr., and Wahl, K. L., 1993, summary of the 
    nationwide analysis of the cost effectiveness of the
    U.S. Geological Survey stream-gaging program (1983-88):
    U.S. Geological Survey Water-Resources Investigations
    Report 93-4168, 27 p.




                                  Ernest F. Hubbard
                                  Acting Chief
                                  Office of Surface Water

Attachment

WRD DISTRIBUTION:  FO