U.S. GEOLOGICAL SURVEY WATER-RESOURCES INVESTIGATIONS REPORT 93-4076 HYDRO-CLIMATIC DATA NETWORK (HCDN) STREAMFLOW DATA SET, 1874-1988 [This is the \HCDN\1ST_READ.ME file] Structure of the HCDN directory This directory (\HCDN) contains files giving attributes and characteristics of the streamflow stations in the HCDN. This directory also contains three sub-directories giving the HCDN streamflow data in ASCII form, the HCDN streamflow data in binary form, and the formats of the data files. \HCDN - This directory contains ASCII files describing the HCDN data base and the stations in it. These files are: STATIONS.DAT is the master index to the streamflow records and gives for each station the following information: Station number State Station name County Hydrologic Unit Code (HUC) Latitude Drainage area Longitude Time scale Datum Portion of record Noncontributing drainage area Number of lines of comments Benchmark indicator District Current Conditions indicator See the STATIONS.FMT file in the FORMATS sub-directory for details of the file layout. BASINS.DAT gives the following eleven items of physical information about the drainage basin: Main channel slope Stream length Mean basin elevation Area of lakes, ponds, and swamps Area of lakes and ponds Forested area Area of glaciers Soil index (soil water storage) Precipitation intensity Mean annual precipitation Mean minimum January temperature See the BASINS.FMT file in the FORMATS sub-directory for details of the file layout. WYEARS.DAT gives the temporal extent (period of record) of the streamflow data for each station. See the WYEARS.FMT file in the FORMATS sub-directory for details of the file layout. COMMENTS.DAT gives comments about the suitability, environment, and situation of many of the stations. See the COMMENTS.FMT file in the FORMATS sub-directory for details of the file layout. STATES.DAT gives the correspondence between the state codes used in the STATIONS.DAT file and the state names. See the STATES.FMT file in the FORMATS sub-directory for details of the file layout. HUCS.TXT gives an explanation of hydrologic units, regions, sub-regions, accounting units, cataloging units, and hydrologic unit codes (HUC). HUC_NAME.TXT gives the full description of all the hydrologic units. See the HUC_NAME.FMT file in the FORMATS sub-directory for details of the file layout. HUC_AREA.DAT gives the drainage area of the hydrologic units by region, subregion, accounting unit, and cataloging unit. See the HUC_AREA.FMT file in the FORMATS sub- directory for details of the file layout. SREGIONS.DAT gives the names of the hydrologic regions and subregions. See the SREGIONS.FMT file in the FORMATS sub- directory for details of the file layout. This directory also contains several sub-directories. They are: \HCDN\FORMATS directory contains the detailed formats and descriptions of the files of streamflow and supporting data. This directory contains the .FMT files. \HCDN\ASCII\DAILYA directory contains the daily values of streamflow in ASCII form in 21 sub-directories. See the ADV.FMT file in the FORMATS sub-directory for details of the file layout. \HCDN\ASCII\MONTHLYA directory contains the monthly mean values of streamflow in ASCII form in 21 sub-directories. See the AMM.FMT file in the FORMATS sub-directory for details of the file layout. \HCDN\ASCII\ANNUALA directory contains the annual mean values of streamflow in ASCII form in 21 sub-directories. See the AAM.FMT file in the FORMATS sub-directory for details of the file layout. \HCDN\BINARY\DAILYB directory contains the daily values of streamflow in binary form in 21 sub-directories. See the BDV.FMT file in the FORMATS sub-directory for details of the file layout. \HCDN\BINARY\MONTHLYB directory contains the monthly mean values of streamflow in binary form in 21 sub-directories. See the BMM.FMT file in the FORMATS sub-directory for details of the file layout. \HCDN\BINARY\ANNUALB directory contains the annual mean values of streamflow in binary form in 21 sub-directories. See the BAM.FMT file in the FORMATS sub-directory for details of the file layout. Directory and file structure within the ASCII and binary 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) found in STATIONS.DAT for the station. These first two digits are the Water Resources Council region in which the station is located. (See HUCS.TXT in the HCDN directory for a detailed explanation.) ASCII and binary data file names For the ASCII and binary forms of the streamflow data, there is one file for each station for each form of data and each time span of data. The name of each file is ssssssss.ttt where ssssssss is the eight digit USGS station name, ttt is AAM for ASCII Annual Mean values (ASCII\ANNUALA), ADV for ASCII Daily Values (ASCII\DAILYA), AMM for ASCII Monthly Mean values (ASCII\MONTHLYA), BAM for Binary Annual Mean values (BINARY\ANNUALB), BDV for Binary Daily Values (BINARY\DAILYB), and BMM for Binary Monthly Mean values (BINARY\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). 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.