durhyd(1)        U.S. Geological Survey (wrdapp)        durhyd(1)


NAME
       durhyd - Duration hydrograph analysis

ABSTRACT
       DURHYD determines percentiles of daily flows for each day of the
       year for the period of record.  Input is daily values stored on a
       Watershed Data Management (WDM) file and output is a table as a text
       file and a plot of the percentiles.

METHOD
       For each day of the year, all values are retrieved for the period of
       record, then ranked.  The ranked values are assigned probabilities
       as m/(n+1) where m is the rank and n is the number of values.  The
       percentiles are then determined by linear interpolation.

HISTORY
       1996 - DURHYD has been incorporated into SWSTAT.  There is no longer
       a separate program for DURHYD.

       The original program K956 was written for the WATSTORE system but
       offered no options to the user.  DURHYD was written from scratch in
       1993 by Alan Lumb to contain the additional functionality requested
       by users.

DATA REQUIREMENTS
       Daily values stored on a WDM file are used for input.  The programs
       ANNIE and IOWDM can be used to reformat data to a WDM file.  The
       program is interactive using the AIDE user interface.  The user can
       use the default probabilities for the percentiles or can input up to
       12 probabilities.  Other inputs are specifications for the plot if
       the defaults are not used.

OUTPUT OPTIONS
       Output tables are placed in text files.  Duration hydrograph plots
       meeting USGS publication standards can be displayed on the screen,
       converted to a postscript file for output on a laser printer, or
       redirected to a metafile.

SYSTEM REQUIREMENTS
       UNIX-based computers (supported:  Data General AViiON with PRIOR
       Graphical Kernel System (GKS) installed and Sun SPARCstation).

       SWSTAT is written in Fortran and C.  A GKS library is required to
       recompile this program.  Generally, it is easily installed on other
       platforms.

DOCUMENTATION
       Context-sensitive help is available in the program.

REFERENCES
       Hutchison, N.E., 1975, WATSTORE User's Guide, Volume 1:  U.S.
          Geological Survey Open-File Report 75-426.





                            7 Jul 1998                          1





durhyd(1)        U.S. Geological Survey (wrdapp)        durhyd(1)


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

          h2osoft@usgs.gov

       Latest version by anonymous ftp from:
             water.usgs.gov
             /pub/software/surface_water/durhyd

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






































                            7 Jul 1998                          2