hydrostats (version 0.2.9)

baseflows: Measures of central tendency and baseflow via the Lynne-Hollick (LH) baseflow filter

Description

Calculate measure of central tendency and baseflow indices using the Lynne-Hollick filter

Usage

baseflows(flow.ts, a, n.reflected = 30, ts = "mean")

Arguments

flow.ts

Dataframe with date and discharge data in columns named "Date" and "Q" respectively. Date must be in POSIX format (see ts.format). Missing values are ignored.

a

The alpha value used in the Lynne-Hollick filter for digital baseflow separation. Default value is 0.975

n.reflected

The number of days that are reflected at the start and end of the series to provide a burn in for the digital filter. Default value is 30. (See Ladson et al. 2013).

ts

ts="mean" returns means for the entire time series ts="annual" returns annual averages. Note this function does not currently use hydrologic years even when defined ts="daily" returns complete series

Value

A dataframe. See below for details. The original dataframe with appended columns "bf" and "bfi". See ts="annual" for details.

ts="mean"

n.years

The number of years of record in the series

prop.obs

proportion of non-missing observations

MDF

mean daily flow

Q50

median daily flow

mean.bf

mean baseflow volume

mean.bfi

mean baseflow index

ts="annual"

year

the record year

no.obs

no of observations in each year

Q

mean daily flow in each year

bf

mean baseflow volume in each year

bfi

baseflow index for each year

ts="daily"

bf

baseflow index for each observation

bfi

baseflow index associated with each observation

Details

Technically the LH filter cannot be calculated where there are missing data. Here the function removes missing values and is applied to a concatenated version of the time series. Missing dates are reinserted after the filter has been applied for the purpose of returning annual or daily series. The function further reports the number of missing values leaving the user to decide on the reliability of the baseflow estimates.

References

Ladson, A. R., R. Brown, B. Neal and R. Nathan (2013) A standard approach to baseflow separation using the Lyne and Hollick filter. Australian Journal of Water Resources 17(1): 173-18

Lynne, V., Hollick, M. (1979) Stochastic time-variable rainfall-runoff modelling. In: pp. 89-93 Institute of Engineers Australia National Conference. Perth.

Examples

# NOT RUN {
data(Acheron)
Acheron<-ts.format(Acheron)

baseflows(Acheron,a=0.975, ts="mean")
baseflows(Acheron,a=0.975, ts="annual")
head(baseflows(Acheron,a=0.975, ts="daily"))


# }