getPred_baseflow: Create a vector of baseflow rates.

In McDowellLab/loadflex: Models and Tools for Watershed Flux Estimates

Description

Internal for now; not yet ready to be a part of the official API

Usage

getPred_baseflow(data, metadata, method = c("hysep", "1p digital filter",
  "2p digital filter"), da, select, alpha, BFImax, ...)

Arguments

data	data.frame with columns as specified by metadata
metadata	object of class metadata from which Flow and Date columns will be selected.
method	character naming the method to be used. May be specified by the first character or characters, e.g., "h", "1", or "2". See details for a description of each algorithm.
da	numeric, required for method="hysep". As described in ?DVstats::hysep, 'the drainage area of the basin in square miles.'
select	character, optional argument to method="hysep". As described in ?DVstats::hysep, 'a character string indicating which method to use for the baseflow in the output dataset. Must be one of "sliding," "local minimum," or "fixed." Onle the first letter is required.' See the HYSEP documentation by Sloto and Crouse at https://water.usgs.gov/software/HYSEP/code/doc/hysep.pdf for method descriptions.
alpha	numeric, required argument for method %in% c("1p digital filter","2p digital filter"). Adjusts the strength of the filter, with numbers closer to 1 leading to more of total flow being classified as runoff (non-baseflow). For the 2-parameter digital filter, the default is 0.98.
BFImax	numeric, required argumend for method=="2p digital filter". The maximum long-term fraction of total streamflow that may be classified as baseflow. Recommended values are 0.8 for perennial streams with porous aquifers, 0.50 for ephemeral streams with porous aquifers, and 0.25 for perennial streams with hard rock aquifers. (Defaults from https://user.engineering.uiowa.edu/~flood/handouts/ HO-L17-Baseflow-Separation.pdf)
...	other arguments passed to the specified method (currently only 'hysep' takes other arguments; see ?DVstats::hysep)

Details

Given a dataset with date and flow columns, separates total flow into baseflow and runoff; returns a vector of baseflow rates. Several methods are available and can be selected with the "method" argument. All methods assume that the time series is evenly spaced, and all work better with higher-resolution data (e.g., hourly or daily rather than weekly or monthly).

method=="1p digital filter": Uses the one-paramter digital filter described by Nathan, R.J. and T.A. McMahon, 1990. Evaluation of Automated Techniques for Baseflow and Recession Analysis. Water Resources Research, 26(7):1465-1473. This method requires specification of the alpha parameter.

method=="2p digital filter": Uses the two-parameter digital filter described by Eckhardt, K., 2005. How to Construct Recursive Digital Filters for Baseflow Separation. Hydrological Processes, 19(2):507-515. This method requires specification of the alpha and BFImax parameters.

References

Implementation of the 1- and 2-parameter digital filters was aided by the online lecture notes of A. Allen Bradley, Jr. for his Fall 2013 Hydrology course (https://user.engineering.uiowa.edu/~flood)

See Also

Other predictors: getPred_isBaseflow

McDowellLab/loadflex documentation built on May 8, 2019, 9:48 a.m.