The "Manual on Low-flow Estimation and Prediction", published by the World Meteorological Organisation (WMO), gives an idea how to analyse stream flow data focusing on low-flow issues. This packages gives functions to compute the described statistics and produce plots similar to the one in the manual.
### Create lfobj (Low-Flow-Objects)
The package calculates indices and makes graphics for low flow analysis. It brings its own class "lfobj", a special data.frame format with columns "day", "month", "year", "flow", "hyear" and possibly "baseflow".
"day", "month" and "year" refer to the date, "flow" is the measured runoff (unit-independent), "baseflow" the calculated baseflow.
"hyear" refers to the hydrological year. When creating the "lfobj" you define the month where the stations hydrological year starts. If annual indices are calculated or single years are plotted, the "hyear" is taken.
Basically there are to options to create an lfobj:
If you have special data format, e.g. GRDC, you can use the function
readlfdata, see '?readlfdata' to see which formats are currently
Otherwise you can use
createlfobj. You can apply it for new data in
one of two ways:
1) You create a data.frame with columns: "day", "month", "year" and
2) You create a time-series (ts) from "flow" and give the start date of
the series when calling 'createlfobj'.
lfstat does not need to know the unit of the flow, but you might want it
to appear in your plots. You can use
setlfunit to define how units are
labelled in your graphics. Examples are given in '?setlfunit'.
Please check for NA-values using
lfnacheck, indices and plots are made
as if series were complete. See the manual on how to deal with missing
values and, if reasonable, use
MAM (mean annual minima),
recession (recession constant),
streamdef (Streamflow deficit),
(Extreme value - T-years event),
recessionplot (Diagnosis for recession)
sbplot (seasonal barchart)
seglenplot (select recession length for
streamdefplot (Streamflow deficit)
rfa (Regional frequency analysis)
dmcurve (Double mass curve)
Gustard, A. & Demuth, S. (2009) (Eds) Manual on Low-flow Estimation and Prediction. Operational Hydrology Report No. 50, WMO-No. 1029, 136p.
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