The USGS instantaneous hourly flow data were acquired from the USGS's ADAPS system or from USGS field office personnel. The data
include some corrections and shifts but are not defined as "approved" like the mean daily flow data available from the NWIS web
site. However, we have performed some rudimentary quality control steps of our own. This involved:
(1) downloading the approved mean daily flow data from the NWIS web site for the same time periods
(2) computing mean daily flow from the hourly data,
(3) visually comparing the derived and approved daily flow time series, hourly streamflow data, mean areal precipitation data,
and basic simulations for each basin, and
(4) flagging any suspicious data in the hourly time series as missing.
Examples of suspicious data included (1) days for which our computed mean daily flow does not closely match the approved USGS
daily flow, (2) days when the approved daily flow values are set to missing but the hourly data show values, and (3) periods when
the hourly flow shows a sudden rise with no corresponding rainfall. Most of the instances when the computed daily flow
significantly deviated from the approved USGS mean daily flows were during low flow periods.
Each hourly streamflow file is composed of comments (starting with $), a two-line header, and then followed by the streamflow
data. For example, the first five lines of the data for Baron Fork at Eldon (ELDO2) are:
$ORMS OUTPUTS FOR ELD02
ORMS OUTPUTS QIN L3/T CMS
10 1995 9 2002 1 F13.2
BASIN 011095 1 1.73
BASIN 011095 2 1.73
Where in the header lines (2 and 3):
||-- NWS internal file identifier;
||-- NWS data type (instantaneous observed hourly discharge);
||-- streamflow units (cubic meter / second);
||-- starting time (month/year);
||-- ending time (month/year);
||-- time step, in this case hourly discharge
||-- data format. This Fortran field starts in column 20 of the data.
The streamflow data are listed after the header:
||--NWS internal code
||--day/month/year time code (dd/mm/yr)
||-- number of the hour, in this case the first hour of the day (UTC).
||--discharge at hour 1
NOTE: the data files contain complete months. In other words, the first value in the data file is for the end of the first hour
of the first day of the month (June in the example). The last data value in the file is for the last hour of the last day of the
specified month (September in the above example).