Find the start, middle, end, and duration of seasonal droughts

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Description

This function returns the day of year for the start, middle, and end of seasonal droughts. It also returns the duration and severity of each drought event. The function allows for seasonal analysis by defining a season argument which lists months during which droughts of interest may start.

Usage

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dr.seas(TS, Qdr = 0.2, WinSize = 30, IntEventDur = 10, EventDur = 15,
  Season = c(4:9))

Arguments

TS

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

Qdr

Numeric value for drought quantile. Default is 0.2.

WinSize

Numeric value for moving window size 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. Default is 10.

EventDur

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

Season

Numeric vector of months during which droughts start. Default is c(4:9) for non-frost season droughts.

Details

This function calls dr.events which calls dr.pds and mqt

Value

Returns a data.frame of drought event metrics; the columns are:

  • StartDay - day of year that the drought event started on

  • MidDay - day of year for the middle of the drought event, which is defined as the day when the cumulative drought deficit reached 50 total cumulative daily streamflow deficit. Total cumulative streamflow deficit is also referred to as drought severity in this package.

  • EndDay - day of year that the drought ended on

  • Duration - length of the drought event, in days

  • Severity - severity of the drought event, calculated as the total cumulative daily streamflow deficit

The "times" attribute provides the start date to preserve year information and aid in plotting the time series.

Author(s)

Jennifer Dierauer

See Also

See create.ts to format the input flow series.
See dr.events and mqt for details on how drought events are defined.

Examples

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data(cania.sub.ts)
res <- dr.seas(cania.sub.ts)
res2 <- screen.metric(res[,1], "Day of Year")

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