U.S. GEOLOGICAL SURVEY WATER-RESOURCES INVESTIGATIONS REPORT 93-4076 HYDRO-CLIMATIC DATA NETWORK (HCDN) STREAMFLOW DATA SET, 1874-1988 [This is the \DOCFILES\NON-DOS.DOC file] THE HCDN FILES There are two types of data on the HCDN CD-ROM: supporting data and the streamflow data. THE SUPPORTING DATA The supporting data gives information about the stations at which the streamflow data was collected and their environment and setting. Four files which contain supporting data and are the most useful for searching for desired stations are: STATIONS.DAT is the master index to the streamflow records and gives the number, name, location, hydrologic unit code, and other information about each station. BASINS.DAT gives eleven items of physical information about the drainage basin such as stream length, percent of forest cover, and precipitation for each station. WYEARS.DAT gives the temporal extent (period of record) of the streamflow data for each station. COMMENTS.DAT gives comments about the suitability, environment, and situation of many of the stations. Each of these files is in the \HCDN directory. Further information describing the contents of these files may be found in the 1ST_READ,ME file in that directory. Detailed information on the format or layout of each of these files may be found in the STATIONS.FMT, BASINS.FMT, WYEARS.FMT, and COMMENTS.FMT files, respectively, in the FORMATS sub-directory of the HCDN directory. The common element (key) among these files is the eight digit USGS station number. It is the first eight characters of each line (record) of these four files. Each file is ordered (sorted) on this common field. Once you have examined these files and determined which stations you wish to use, note the first two digits of the Hydrologic Unit Code (HUC) associated with each of the desired stations in the STATIONS.DAT file. This tells which REGIONrr sub- directories (described below) the streamflow data is in. THE STREAMFLOW DATA The streamflow data is available in the HCDN directory in two forms - ASCII and binary. The ASCII (text) form is for the user who may want to use a word processor or data-base package to extract and manipulate the data and feed it to another program such as a statistics package or spread-sheet. Data in the ASCII form can be read and processed on any computer that can handle a CD-ROM in the ISO 9660 format. The binary form is specifically for the user who intends to write a program (Fortran, C, Pascal, etc.) to read the files since reading binary data is 6 to 15 times faster than reading ASCII data. Sub-directories in the HCDN directory: FORMATS directory contains the detailed formats and descriptions of the files of streamflow and supporting data. This sub-directory contains the .FMT files. ASCII directory contains the streamflow data in ASCII form in three sub-directories according to the time span of the data. DAILYA directory contains the daily values in ASCII form in 21 sub-directories. MONTHLYA directory contains the monthly mean values in ASCII form in 21 sub-directories. ANNUALA directory contains the annual mean values in ASCII form in 21 sub-directories. BINARY directory contains the streamflow data in binary form in three sub-directories according to the time span of the data. DAILYB directory contains the daily values in binary form in 21 sub-directories. MONTHLYB directory contains the monthly mean values in binary form in 21 sub-directories. ANNUALB directory contains the annual mean values in binary form in 21 sub-directories. Structure within the ASCII and binary data sub-directories: Within each of the ASCII and binary directories, there are 21 sub-directories holding the files containing the data. Each of these directories has the name REGIONrr. The data for a particular station is located in the directory REGIONrr where rr is the first two digits of the hydrologic unit code (HUC) for the station. This is the Water Resources Council region in which the station is located. (See HUCS.TXT in the HCDN directory for a detailed explanation.) RECORD FORMATS The ASCII and binary data formats are designed to carry all of the data in the most concise manner possible and be of fixed length. The records do not exceed 128 characters in the ASCII form. All of the data is organized by water year. A water year starts on October 1st and ends on the following September 30th. A water years is called by the year it ends in. For example, water year 1988 - the last water year considered for inclusion in the HCDN - runs from October 1, 1987 through september 30, 1988. ASCII AND BINARY DATA FILE NAMES For the ASCII and binary forms of the data, there is one file for each station for each form of data and each time interval of data. The name of each file is ssssssss.ttt where ssssssss is the eight digit USGS station name and ttt is AAM for ASCII Annual Mean values (under sub-directory ANNUALA), ADV for ASCII Daily Values (under sub-directory DAILYA), AMM for ASCII Monthly Mean values (under sub-directory MONTHLYA), BAM for Binary Annual Mean values (under sub-directory ANNUALB), BDV for Binary Daily Values (under sub-directory DAILYB), and BMM for Binary Monthly Mean values (under sub-directory MONTHLYB). Within each file there is one record for each year except for the ASCII form of the daily values where there is one record for each day of the month (31 records to a water year). See the appropriate .FMT file in the FORMATS sub-directory of the HCDN directory.