Water Resources Applications Software

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Summary of PEAKFQ

     peakfq - Flood-frequency analysis based on Bulletin 17B

     PEAKFQ performs flood-frequency analysis based on the
     guidelines delineated in Bulletin 17B, published by the
     Interagency Advisory Committee on Water Data in 1982.  The
     program is interactive and contains the code from the
     WATSTORE program J407.

     PEAKFQ uses the method of moments to fit the Pearson Type
     III distribution to the logarithms of annual flood peaks.
     The skew that is used may be a user-developed generalized
     skew for a region, from the Bulletin 17B skew map, computed
     from the data, or weighted between the generalized skew and
     station skew computed from the data.  Adjustments can be
     made for high and low outliers and historic information.
     Qualification codes may be used to censor data from the

     The program was written in the early 1980's by W. Kirby as
     WATSTORE program J407.  In the late 1980's, J407 was
     included in the program ANNIE (Lumb and others, 1990) for
     minicomputers and the PC.  The current program completed in
     1993 for PC's, UNIX workstations, and minicomputers was
     removed from ANNIE, and is a separate program that uses the
     AIDE user interface (Kittle and others, 1989), has keyboard
     data entry as well as a flat file, and the Watershed Data
     Management (WDM) file.

     Version 4.1 2002/02/25 - Corrected problems with outputting
        the 1.5 and 2.33 -year flood peaks.  Revised code to
        write summary of statistics to screen for case where
        input is from a wdm file and the user has selected YES
        for "pause between stations" and NONE for "additional

     Version 4.0 2000/12/01 - Revised how skew option was
        handled.  There were some problems with how the skew
        option was handled when multiple data sets were processed
        and some of the data sets did not have the skew option
        defined; program now warns user and defaults to weighted
        skew for those data sets.  Systematic frequency curve was
        previously drawn over the same probability range as the
        Bulletin 17B curve, it is now drawn over the range of the
        data values.  The program now reports the 1.5 and 2.33
        year floods.

     Version 3.0 - there was no 3.0 distribution.

     Version 2.5 1999/07/30 - No changes in computations.
        Revised how skew option was handled.  There had been some
        problems when multiple wdm data sets were processed and
        some of them were missing attributes for the skew option;
        the program now warns the user and defaults to weighted
        skew.  Code groups have been slightly reorganized;
        subroutine frqplg has been moved to the libanne awstat
        library and duplicated code has been replaced with calls
        to dsinf1 (libanne awstat library) and svati4, svatr1,
        and svatr2 (libanne waide library).

     Version 2.4 1998/03/06 - There are no corrections made to
        the actual computations in peakfq; all changes are
        cosmetic or made to clarify meaning.  User's log files
        may need to be modified for cases that specify no pause
        and no modifications for ASCII input.

     Version 2.3 1997/01/07 - Implemented option to save the
        computed statistics in the WATSTORE basin characteristics
        'card' format.  Correction in computation of generalized
        skew caused by incorrect conversion of degree-minute-
        second latitude and longitude to decimal degrees (rarely
        a problem as latitude and longitude are usually entered
        in decimal degrees).  Correction problem with incorrectly
        printed y-axis scale value in the printer plot option
        (roundoff problem found with pc compiler, caused some
        scale values smaller than 1.0 to be incorrectly printed,
        while the data were correctly scaled.)

     Version 2.2 1995/10/27 - Added an option to allow user to
        specify that they want to [yes/no] pause between stations
        (useful when many stations are being processed).  Correct
        problem where option flag for including regulated flows
        was not always correctly set.

     Version 2.0 1994/02 - A new interpolation method for looking
        up frequency-curve ordinates (discharges) for given
        exceedance probabilities.  The new method uses
        computations equivalent to straight-line interpolation on
        probability paper, whereas the original method was
        equivalent to straight-line interpolation on ordinary
        arithmetic (rectangular) graph paper.   The
        interpolations are performed only when the flood record
        contains low outliers, zero flows, or flows below the
        gage base.   The magnitude of the difference between the
        two methods can be assessed roughly by plotting the
        frequency curves tabulated in Bulletin 17-B for skews of
        0 and 1.0 on ordinary arithmetic graph paper and
        comparing straight-line interpolation between the plotted
        points with a smooth curve drawn through the points.
        (For skew of -1.0, the results can be obtained by
        interchanging the upper and lower tails of the +1.0-skew

        The new method is considered to be an improvement over
        the original method.  However, the original method also
        conformed to Bulletin 17-B, and the results of the
        original method are not considered significantly
        different from those of the new method.   In interpreting
        or applying the results of any flood-frequency
        computation, the statistical-sampling uncertainty
        entailed by the length of the flood-data record should be
        kept in mind.  The magnitude of this uncertainty is
        indicated by the confidence limits printed along with the
        Bulletin-17B flood magnitude estimates.

        Results computed with the February 1994 version (and
        later) of the peakfq program are based on the new
        interpolation method.  Results from earlier versions of
        the program are still usable.

     Program input can be a text file in the format described in
     the WATSTORE User's Manual, v. 4, chap. I, sec. A; a WDM
     file; or interactively input with forms displayed on the
     screen.  Input usually comes from a WDM file if regional
     analysis with the GLSNET program is planned.  WDM files are
     binary, direct-access files that allow for efficient storage
     and fast retrieval of a large number of data sets.  WDM
     time-series data sets with a yearly time step or table data
     sets are used by PEAKFQ.  The most effective way to add
     peak-flow data to a WDM file is to use IOWDM, choosing the
     WATSTORE peak-flow, card-image format option.

     Output tables are placed in a text file.  Computed
     statistics are, optionally, placed on the WDM data set as
     attributes for further processing.  Frequency plots meeting
     USGS publication standards can be displayed on the screen.
     Additional plot output options depend on the devices
     supported by the GKS library used and may include
     PostScript, Computer Graphics Metafile (CGM), Hewlett-
     Packard Graphics Language (HP-GL), and assorted printers and
     plotters.  See the installation instructions (README.TXT)
     for details of output devices available with precompiled
     distributions of the program.

     PEAKFQ is written in Fortran 77 with the following
     extensions: use of include files, INTEGER*2 variables, and
     Hollerith constants.  Common blocks have mixed character and
     noncharacter data.  The ANN, WAIDE, AWSTAT, GRAPH, STATS,
     AIDE, WDM, ADWDM, and UTIL libraries from LIBANNE are
     required to recompile.  For more information, see System
     Requirements in LIBANNE.

     There have been hundreds of applications used throughout the
     United States and the results of these analyses have been
     published in State or regional flood-frequency reports.

     Kirby, W.H., 1981, Annual flood frequency analysis using
        U.S. Water Resources Council guidelines (program J407):
        U.S. Geological Survey Open-File Report 79-1336-I,
        WATSTORE User's Guide, v. 4, chap. I, sec. C, 56 p.
        (Report was updated in 1981.)

     Flynn, K.M., Hummel, P.R., Lumb, A.M., and Kittle, J.L.,
        Jr., 1995, User's manual for ANNIE, version 2, a computer
        program for interactive hydrologic data management:  U.S.
        Geological Survey Water-Resources Investigations Report
        95-4085, 211 p.

     Interagency Advisory Committee on Water Data, 1982,
        Guidelines for determining flood flow frequency: Bulletin
        17-B of the Hydrology Subcommittee, Office of Water Data
        Coordination, U.S.  Geological Survey, Reston, Va., 183
        p. [Available from National Technical Information
        Service, Springfield VA 22161, (telephone (703) 487-4600)
        as report no. PB 86 15 7278.]

     Lumb, A.M., Kittle, J.L., Jr., and Flynn, K.M., 1990, Users
        manual for ANNIE, a computer program for interactive
        hydrologic analyses and data management: U.S. Geological
        Survey Water-Resources Investigations Report 89-4080, 236
        p.  (Documents the 1990 version included in the ANNIE

     Guimaraes, W.B., and Bohman, L.R., 1991, Techniques for
        estimating magnitude and frequency of floods in South
        Carolina, 1988:  U.S. Geological Survey Water-Resources
        Investigations Report 91-4157.

     Krug, W.R., Conger, D.H., and Gebert, W.A., 1992, Flood-
        frequency characteristics of Wisconsin streams:  U.S.
        Geological Survey Water-Resources Investigations Report

     Landers, M.N., and Wilson, K.V., Jr., 1991, Flood
        characteristics of Mississippi streams:  U.S. Geological
        Survey Water-Resources Investigations Report 91-4037, 82

     Lumia, R., 1991, Regionalization of flood discharges for
        rural, unregulated streams in New York, excluding Long
        Island:  U.S. Geological Survey Water-Resources
        Investigations Report 90-4197.

     Weaver, J.D., and Gamble, C.R., 1993, Flood frequency of
        streams in rural basins of Tennessee:  U.S. Geological
        Survey Water-Resources Investigations Report 92-4165.

     Williams-Sether, T., 1992, Techniques for estimating peak-
        flow frequency relations for North Dakota:  U.S.
        Geological Survey Water-Resources Investigations Report

     Statistical Approach to Surface-Water Hydrologic Analysis
     (SW2011TC), offered annually at the USGS National Training

     Operation and Distribution:
        U.S. Geological Survey
        Hydrologic Analysis Software Support Program
        437 National Center
        Reston, VA 20192

     Official versions of U.S. Geological Survey water-resources
     analysis software are available for electronic retrieval via
     the World Wide Web (WWW) at:


     and via anonymous File Transfer Protocol (FTP) from:

       (path: /pub/software).

     The WWW page and anonymous FTP directory from which the
     PEAKFQ software can be retrieved are, respectively:


     for information on ordering printed copies of USGS


     annie(1) - Program to list, table, plot data in a WDM file

     glsnet(1) - Regional hydrologic regression and network
                 analysis using generalized least squares

     hass-cui(1) - Character-based user interface

     iowdm(1) - Program to store time-series data in a WDM file

     swstat(1) - Surface-water statistics

     wdm(1) - Watershed Data Management system

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