FlowScreen (version 0.9)

dr.events: Partial Duration Series and Event Statistics for streamflow droughts

Description

This function extracts the partial duration series for all streamflow droughts based on a moving window quantile threshold. Also returns summary information (start date, end date, duration, deficit volume) for each drought event.

Usage

dr.events(TS, Qdr = 0.2, WinSize = 30, IntEventDur = 10, EventDur = 15)

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.

IntEventDur

Numeric value for the minimum inter-event duration in days. Drought events with less than the specified number of days between will be pooled and considered as one event.

EventDur

Numeric value for the minimum drought duration in days. Default is 15.

Value

• Returns a list with the following elements: DroughtEvents: A data.frame with the following columns:
  • Event - Integer indicating the original event number assigned before minor drought events were removed.
  • Start - Date of the start of the drought event.
  • End - Date of the end of the drought event
  • maxDef - Numeric value of the maximum streamflow deficit.
  • Severity - Numeric value indicating the drought severity, calculated as the cumulative daily streamflow deficit in m3/s.
  • Duration - Numeric value of the drought duration in days.
  • Magnitude - Numeric value indicating the drought magnitude, which is calculated as the mean daily streamflow deficit in m3/s.
  • stdtotDef - Numeric value indicating the standardized cumulative streamflow deficit, calculated as the drought severity divided by the mean annual daily streamflow.
  DroughtPDS: A data.frame of the original input TS that has been subset to include only the days on which the streamflow was below the drought threshold. The data.frame also has the following columns appended:
  • Thresh - Numeric value indicating the streamflow drought threshold, as calculated bymqt
  • BelowThresh - Logical indicating whether the observed streamflow was below the streamflow drought threshold.
  • Def - Numeric value of the streamflow defict, calculated as the streamflow drought threshold (m3/s) minus the observed streamflow (m3/s).

See Also

See dr.seas to calculate metrics for droughts occurring in a user-defined season. This function calls dr.pds which calls mqt.

Examples

data(cania.sub.ts)
res1 <- dr.events(cania.sub.ts)
events <- res1$DroughtEvents
plot(events$Start, events$Duration, pch=19, ylab="Drought Duration (days)", xlab="")