loadReg: Load Estimation

Description Usage Arguments Details Value References See Also Examples

View source: R/loadReg.R

Description

Build a rating-curve (regression) model for river load estimation.

Usage

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loadReg(formula, data, subset, na.action, flow, dates, flow.units = "cfs",
  conc.units = "", load.units = "kg", time.step = "day", station = "")

Arguments

formula

a formula describing the regression model. See Details.

data

the data to search for the variables in formula.

subset

an expression to select a subset of the data.

na.action

what to do with missing values.

flow

character string indicating the name of the flow column.

dates

character string indicating the name of the date column.

flow.units

character string describing the flow units. See Details.

conc.units

character string describing the concentration unit. See Details.

load.units

character string describing the load unit. See Details.

time.step

character string describing the time step of the calibration data. Must be one of "instantaneous," "2 hours," "3 hours," "4 hours," "6 hours," "12 hours," or "day." The default is "day."

station

character string description of the station.

Details

The left-hand side of the formula may be any numeric variable, just as with lm or a variable of class "lcens," "mcens," or "qw." Also permitted are variables constructed using Surv of type "right,", "interval," or "interval2" (for left-censored data, use as.lcens.
For un- or left-censored data, AMLE is used unless weights are specified in the model, then MLE is used, through a call to survreg. For any other censored data, MLE is used.

Typically, loadReg expects the response variable to have units of concentration, mass per volume. For these models, See loadConvFactor for details about valid values for flow.units, conc.units and load.units. For some applications, like bed load estimation, the response variable can have units of flux, mass per time. For these models, conc.units can be expressed as any valid load.units per day. The rate must be expressed in terms of "/d," "/dy," or "/day."

Value

An object of class "loadReg."

References

Runkel, R.L., Crawford, C.G., and Cohn, T.A., 2004, Load estimator (LOADEST): a FORTRAN program for estimating constituent loads in streams and rivers: U.S. Geological Survey Techniques and Methods book 4, chap. A5, 69 p.

See Also

censReg, as.lcens, as.mcens, Surv

Examples

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# From application 1 in the vignettes
data(app1.calib)
app1.lr <- loadReg(Phosphorus ~ model(1), data = app1.calib, 
 flow = "FLOW", dates = "DATES", conc.units="mg/L",
 station="Illinois River at Marseilles, Ill.")
print(app1.lr)

USGS-R/rloadest documentation built on Oct. 2, 2020, 5:21 a.m.