Entry ID: USGS_SWSTAT
Abstract: Surface-water statistics (SWSTAT) contains a number of options for
statistically analyzing time-series data. The time-series data are read
from a Watershed Data Management (WDM) file. The computed
statistics and (or) time series can be written back to the
WDM file or to a text file. The statistics options include:
Basic: Computes minimum, maximum, mean, and standard
... deviation of a time series (any time step).
Compare: Uses flow-duration analysis and class intervals
to compute absolute error, root mean square
error, and bias by class interval for two time
series. The standard error of estimate is
computed. The flow-durations curves can be
plotted. Data may be any time step.
Duration: Performs traditional flow-duration analysis by
counting occurrences of all time-series values
within flow intervals. The duration curve can
be plotted. Data are analyzed at a daily time
Frequency: Analyzes time series using log-Pearson Type III
distribution, without the extra features of
Bulletin 17B found in the PEAKFQ program. The
distribution is fitted by method of moments.
Based on the USGS A193 WATSTORE program. Data
are read from time-series data sets and analyzed
at an annual time step.
Hydrograph: Computes duration hydrograph tables and curves.
Based on the USGS K956 WATSTORE program. The
duration hydrograph curves may be plotted. Data
are analyzed at a daily time step. Although
originally developed for streamflow data, any
time series may be analyzed.
N-day: Computes annual n-day high and (or) low flows
from a daily time series. A default set of 1-,
2-, 3-, 7-, 10-, 30-, 60-, 90-, 183-, and
365-day periods can be selected, or up to 10
durations may be specified. Analysis may be
over a calendar year, water year, or a season.
Based on the USGS A969 WATSTORE program.
Trend: Tests annual time series for trends. Computes
Kendall's tau, the associated p-level and the
slope of the trend line. The p-level is the
attained (two-sided) significance level of the
test. The data may be read from a time-series
data set or from a table data set.
[Summary provided by the USGS.]
Arihood, L.D., and Glatfelter, D.R., 1991, Method for estimating low-flow
characteristics of ungaged streams in Indiana: U.S. Geological Survey
Water-Supply Paper 2372.
Bingham, R.H., 1985, Low flows and flow duration of Tennessee streams through
1981: U.S. Geological Survey Water-Resources Investigations Report 84-4347.
Bingham, R.H., 1986, Regionalization of low-flow characteristics of Tennessee
streams: U.S. Geological Survey Water-Resources Investigations Report 85-4191.
Giese, G.L., and Mason, R.R., 1990, Low-flow frequency characteristics of
streams in North Carolina: U.S. Geological Survey Open-File Report 90-399.
Hayes, D.C., 1991, Low-flow characteristics of streams in Virginia: U.S.
Geological Survey Water-Supply Paper 2374.
Ludwig, A.H., 1992, Flow duration and low-flow characteristics of selected
Arkansas streams: U.S. Geological Survey Water-Resources Investigations Report
92-4026, 77 p.
Ruhl, K.J., and Martin, G.R., 1991, Low-flow characteristics of Kentucky
streams: U.S. Geological Survey Water- Resources Investigations Report
91-4097, 51 p.
Telis, P.A., 1991, Low-flow and flow-duration characteristics of Mississippi
streams: U.S. Geological Survey Water-Resources Investigations Report 90-4087,
Creation and Review Dates