U.S. Geological Survey peakfq(1) NAME peakfq - Flood-frequency analysis based on Bulletin 17B ABSTRACT 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. METHOD 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 analysis. HISTORY 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 output". 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. Last change: 25 February 2002 1 U.S. Geological Survey peakfq(1) 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 Last change: 25 February 2002 2 U.S. Geological Survey peakfq(1) curve.) 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. DATA REQUIREMENTS 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 OPTIONS 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. SYSTEM REQUIREMENTS 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 Last change: 25 February 2002 3 U.S. Geological Survey peakfq(1) Requirements in LIBANNE. APPLICATIONS 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. DOCUMENTATION 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.) RELATED DOCUMENTATION 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 program.) REFERENCES 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 91-4128. 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 p. Last change: 25 February 2002 4 U.S. Geological Survey peakfq(1) 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 92-4020. TRAINING Statistical Approach to Surface-Water Hydrologic Analysis (SW2011TC), offered annually at the USGS National Training Center. CONTACTS Operation and Distribution: U.S. Geological Survey Hydrologic Analysis Software Support Program 437 National Center Reston, VA 20192 h2osoft@usgs.gov Official versions of U.S. Geological Survey water-resources analysis software are available for electronic retrieval via the World Wide Web (WWW) at: http://water.usgs.gov/software/ and via anonymous File Transfer Protocol (FTP) from: water.usgs.gov (path: /pub/software). The WWW page and anonymous FTP directory from which the PEAKFQ software can be retrieved are, respectively: http://water.usgs.gov/software/peakfq.html --and-- /pub/software/surface_water/peakfq See http://water.usgs.gov/software/ordering_documentation.html for information on ordering printed copies of USGS publications. SEE ALSO Last change: 25 February 2002 5 U.S. Geological Survey peakfq(1) 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 Last change: 25 February 2002 6