ev_return_period: Estimate the return period for given quantiles

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

Description

For discharges of interrest,

Usage

ev_return_period(x, fit)

Arguments

x	numeric vector containting the quantiles
fit	object of class evfit describing the underlying distribution, possibly created with evfit().

Value

a numeric vector of return periods.

See Also

evfit

Examples

data("ngaruroro")
ng <- as.xts(ngaruroro)

# yearly minima
minima <- apply.yearly(ng$discharge, min, na.rm = TRUE)

# fit a Weibull distribution
fit <- evfit(x = as.vector(minima), distribution = "wei")

# compute return periods
minima$rp <- round(ev_return_period(minima, fit), 2)

print(minima)
plot(discharge ~ rp, data = minima,
     xlab = "Flow in m^3/s", ylab = "Return period in years")

Example output

Loading required package: xts
Loading required package: zoo

Attaching package: 'zoo'

The following objects are masked from 'package:base':

    as.Date, as.Date.numeric

Loading required package: lmom
Loading required package: lattice
           discharge    rp
1963-12-31     4.975  1.19
1964-12-31     3.344  5.11
1965-12-31     4.805  1.27
1966-12-31     5.019  1.18
1967-12-31     4.819  1.26
1968-12-31     3.210  6.56
1969-12-31     3.832  2.56
1970-12-31     3.849  2.51
1971-12-31     4.872  1.23
1972-12-31     3.851  2.50
1973-12-31     2.780 19.34
1974-12-31     3.018 10.00
1975-12-31     4.677  1.34
1976-12-31     4.840  1.25
1977-12-31     4.085  1.99
1978-12-31     2.596 37.58
1979-12-31     2.944 12.05
1980-12-31     6.181  1.01
1981-12-31     5.461  1.07
1982-12-31     3.419  4.50
1983-12-31     2.691 26.10
1984-12-31     4.844  1.25
1985-12-31     4.074  2.00
1986-12-31     3.969  2.21
1987-12-31     4.196  1.81
1988-12-31     4.279  1.70
1989-12-31     3.900  2.38
1990-12-31     4.031  2.09
1991-12-31     3.965  2.22
1992-12-31     4.570  1.41
1993-12-31     3.813  2.61
1994-12-31     3.244  6.14
1995-12-31     4.462  1.50
1996-12-31     5.882  1.02
1997-12-31     3.959  2.24
1998-12-31     3.375  4.84
1999-12-31     4.548  1.43
2000-12-31     3.839  2.54

lfstat documentation built on May 2, 2019, 6:07 p.m.