pool_ic: Pooling Procedures of Low Flow Events

In lfstat: Calculation of Low Flow Statistics for Daily Stream Flow Data

Pooling Procedures of Low Flow Events

Description

Several pooling procedures can be applied to reduce the number of dependent droughts.

Usage

pool_ic(x, tmin = 5, ratio = 0.1)
pool_it(x, tmin = 5)
pool_ma(x, n = 10)
pool_sp(x)
  

Arguments

x	an object of class deficit, e.g. as produced by find_droughts.
tmin	numeric vector of length one interpreted as the number of days between two droughts to be considered independent events. Two droughts are pooled if their inter-event time is less than tmin.
ratio	numeric vector of length. Specifies the minimum ratio of inter-event volume and precedent drought volume. Two droughts are pooled if the critical ratio is deceeded.
n	numeric vector of length one determining the width of the smoothing window

Details

The inter-event criterion (pool_ic) pools subsequent drought events if the inter-event time is less than tmin and the ratio of the drought volume and the inter-event volume is less than a given ratio. The function pool_it is simply a wrapper around pool_ic(..., ratio = Inf).

Pooling by a moving average (pool_ma) simply smooths the time series before finding drought events.

Using the Sequent Peak algorithm (pool_sp), a drought lasts until its cumulative deficit volume is zero again.

Value

an object of class deficit (inherited from xts), with an additional column event.orig.

See Also

find_droughts, summary.deficit

Examples

data(ngaruroro)
ng <- as.xts(ngaruroro)
ng <- ng["1986::1990", ]

drought <- find_droughts(ng)


ic <- pool_ic(drought)
summary(ic)

ma <- pool_ma(drought)
summary(ma)

sp <- pool_sp(drought)
summary(sp)
plot(sp)

lfstat documentation built on Nov. 10, 2022, 5:42 p.m.