recessionplot {lfstat}

Recession diagnostic plot

Description

Helps to define the peak level of a low flow object and visualises recession periods.

Usage

recessionplot(lfobj,
              peaklevel = 0.95,
              plot = TRUE,
              peakreturn = FALSE,
              thresplot = TRUE,
              threscol = "blue",
              threshold = 70,
              thresbreaks = c("fixed","monthly","seasonal"),
              thresbreakdays = c("01/06","01/10"),
              recessionperiod = TRUE,
              recessioncol = "darkblue",
              seglength = 7,
              ...)

Arguments

lfobj

A object of class 'lfobj'

peaklevel

A level between 0 and 1 or a logical vector, see details.

plot

Should a plot be made

peakreturn

Should a logical with rain peaks be returned

thresplot

Should the threshold be plotted

threscol

Colour of threshold in plot

threshold

Threshold level (70 refers to Q70)

thresbreaks

"fixed" uses a fixed threshold level, "monthly" calculates the threshold for every month separately, "seasonal" calculates thresholds for every season defined using 'thresbreakdays'.

thresbreakdays

Needed if thresbreaks = 'seasonal' to define the periods for which separate thresholds should be calculated, see details

recessionperiod

Should recession periods be marked

recessioncol

Colour of recession period marks

seglength

The minimum number of days to be marked as recession period

...

Further arguments handed to hydrograph

.

Details

For recession analysis it is necessary to define flood discharge peaks in the hydrograph. The peak level defines a day to be a discharge peak, if peaklevel * flow > flow[day before] and peaklevel * flow > flow[day after].

This function can be used to check different values of the peak level.

Value

If 'peakreturn = TRUE': A logical vector giving rain peaks as TRUE

Author(s)

Daniel Koffler and Gregor Laaha

References

Gustard, A. & Demuth, S. (2009) (Eds) Manual on Low-flow Estimation and Prediction. Operational Hydrology Report No. 50, WNO-No. 1029, 136p.

See Also

recession

Examples

data(ngaruroro)
# To few points identified as peak flood discharge
recessionplot(ngaruroro, peaklevel = .5, start = 1991, end = 1991)

# To many
recessionplot(ngaruroro, peaklevel = .999, start = 1991, end = 1991)

# Good choice?
recessionplot(ngaruroro, peaklevel = .92, start = 1991, end = 1991)

# Getting peakdays for 1991
peak <- recessionplot(ngaruroro, peaklevel = .92, plot = FALSE, peakreturn = TRUE)
rain1991 <- subset(ngaruroro, subset = (hyear == 1991) & peak, select = c(day, month, year))