recession | R Documentation |
Does recession analysis using either the MRC (Master recession curve) or IRS (individual recession segments) method.
recession(lfobj, method = c("MRC", "IRS"), seglength, threshold, peaklevel = 0.95, seasonbreakdays = NULL, thresbreaks = c("fixed", "monthly","seasonal"), thresbreakdays = NULL, plotMRC = TRUE, trimIRS = 0, na.rm = TRUE)
lfobj |
An object of class |
method |
|
seglength |
The length of the duration segments - see the WNO-manual
and use |
threshold |
The threshold level (70 means Q70) |
peaklevel |
A level between 0 and 1 or a logical vector, see details. |
seasonbreakdays |
A vector of break days. Needed if the recession constant should be calculated individually for different seasons, see details. |
thresbreaks |
|
thresbreakdays |
Needed if |
plotMRC |
logical, if TRUE and |
trimIRS |
Should a trimmed mean be used for calculating the IRS-constant? (0 means no, 0.1 means trim by 10 %) |
na.rm |
Should NAs in the series be ignored? |
For recession analysis it is necessary to define flood discharge peaks
in the hydrograph. Argument peaklevel
defines a day to be a
discharge peak, if peaklevel * flow > flow[day before] and
peaklevel * flow > flow[day after]. Use recessionplot
to find a good level or hand a logical vector where TRUE means rain peak.
If 'thresbreakdays'
or 'seasonbreakdays'
is a single day, e.g. '01/06'
, the start of the hydrological year is taken as the second break day. If more than two seasons are to be specified, a vector of all break days is needed.
The overall recession rate in days. If seasons are defined a rate for every season is calculated.
Daniel Koffler and Gregor Laaha
Gustard, A. & Demuth, S. (2009) (Eds) Manual on Low-flow Estimation and Prediction. Operational Hydrology Report No. 50, WNO-No. 1029, 136p.
seglenplot
, recessionplot
data(ngaruroro) recession(ngaruroro,method = "MRC",seglen = 7,threshold = 70)
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