bf_sep_lh {adc}  R Documentation 
Baseflow Seperation
Description
Implements the Lyne and Hollick filter for baseflow seperation. This function utilizes the approach in Ladson et al. (2013).
Usage
bf_sep_lh(discharge, a = 0.98, n = 3, reflect = 30)
Arguments
discharge 
numeric vector of daily discharge values 
a 
alpha, numeric values between 
n 
number of passes for the filter. Must be a numeric value, defaults to 3. 
reflect 
the number of values to reflect at the start and end of

Details
This function implements the LyneHollick filter (Lyne and Hollick, 1979) using the approach detailed in Ladson et al. (2013). The filter is:
Y_{k} = \alpha \times Y_{k1} + \frac{1+\alpha}{2} \times (Q_k  Q_{k1}),
where Y_k
is the filtered quick response at the k^{th}
sample.
Q_k
if the original streamflow and \alpha
is the filter
parameter between [01]
.
Ladson et al. (2013) suggest a standardized approach for applying the filter by: (1) reflecting streamflow at the start and end of the series to address warmup and cooldown; (2) specify the initial value of each pass as the measured flow; and (3) using three passes for the filter (forward, backward, forward); Ladson et al. (2013) also provide additional suggestions for handling missing values and appropriate alpha parameter values that are not covered here.
Value
vector of numeric values representing estimated baseflow.
Note
This function an updated and modified version of the baseflows()
function in the hydrostats package by Nick Bond. The hydrostats version
returns additional summary measures and utilizes different starting values.
Outputs between the two packages will slightly vary.
Author(s)
Nick Bond n.bond@latrobe.edu.au modified by Michael Schramm
References
Lyne, V., & Hollick, M. (1979, September). Stochastic timevariable rainfallrunoff modelling. In Institute of Engineers Australia National Conference (Vol. 79, No. 10, pp. 8993). Barton, Australia: Institute of Engineers Australia.
Ladson, A. R., Brown, R., Neal, B., & Nathan, R. (2013). A standard approach to baseflow separation using the Lyne and Hollick filter. Australian Journal of Water Resources, 17(1), 2534, doi:10.7158/W12028.2013.17.1.
Examples
bf < bf_sep_lh(lavaca$Flow, a = 0.975)
head(bf)