FlowScreen (version 1.2.6)

dr.pds: Get the partial duration series for streamflow droughts

Description

This function returns the partial duration series for streamflow droughts based on a moving window quantile threshold.

Usage

dr.pds(TS, Qdr = 0.2, WinSize = 30)

Arguments

TS

output from create.ts containing a data.frame of flow time series

Qdr

Numeric value of the drought threshold quantile. Default is 0.2.

WinSize

Numeric value specifying the size of the moving window in days. Default is 30.

Value

Returns the input TS data.frame with "Thresh" and "BelowThresh" columns appended. The Thresh column contains the daily flow threshold, and the BelowThresh column is a binary indicating whether the flow on each day was below the drought threshold.

Details

This function defines a daily streamflow threshold and finds the partial duration series of streamflow droughts. Drought events are identified in the daily streamflow time series with the threshold level approach. In this function, the threshold is defined by a moving quantile, where daily threshold values are based on the 80th percentile of the flow duration curve from a 30-day moving window (Beyene et al. 2014). With this method, every day of the year has a different threshold based on the streamflow measured on the day, the 15 days before the day, and the 15 days after the day. The size of the moving window can be modified with the WinSize argument, and the percentile can be modified with the Qdr argument.

References

Beyene, B.S., Van Loon, A.F., Van Lanen, H.A.J., Torfs, P.J.J.F., 2014. Investigation of variable threshold level approaches for hydrological drought identification. Hydrol. Earth Syst. Sci. Discuss. 11, 12765-12797. http://dx.doi.org/10.5194/hessd-11-12765-2014.

See Also

See create.ts to format the input flow series.

See mqt to return only the daily moving quantile threshold.

See dr.events to pool drought events, remove minor events, and calculate metrics.

See dr.seas to calculate metrics for streamflow droughts that start in a specific month or months.

Examples

# NOT RUN {
data(cania.sub.ts)
pds <- dr.pds(cania.sub.ts)
pds <- subset(pds, pds$BelowThresh==TRUE)

# plot the flow time series with black and the drought events in red
plot(cania.sub.ts$Date, cania.sub.ts$Flow, ylab="m3/s", xlab="", type="l")
points(pds$Date, pds$Flow, pch=19, cex=0.7, col="red")
# }