SScamp {HydroMe} | R Documentation |
This selfstarting model evaluates the Campbells water retention function and its parameters. It has an initial attribute that evaluates initial estimates of the parameters Ths, alp, and scal for a given set of data
SScamp(input, Ths, alp, scal)
input |
numeric vector of natural logarithm of suction potential values at which to evaluate the model |
Ths |
a numeric parameter representing the saturated moisture content when suction potential is zero |
alp |
a numeric parameter representing the inverse of air-entry potential |
scal |
a numeric parameter representing the slope of the water retention curve. It is related to pore-size distribution index |
Campbell function is a three-parameter model that does not assume the residual moisture content. The function estimates the parameters in two parts: when the product of alp and input is less than or eaual to unity and when this quantity is geater than unity
a numeric vector of the same length as input.It is the value of the Campbells expression Ths*(alp*input)^(-scal) . It represents the fitted estimates of moisture contents using the Campbell function
Omuto, Christian Thine
SSgard, SSbrook, SSvan
##---- use part of the Wret data ---- data(Wret) nWret=nrow(Wret) # gets the number of rows need (there are 232 all together) testW13 <-Wret[(nWret-231):(nWret-208), ] # choose the first 3 sets Campbel.nls <-nls(y~SScamp(lnx, Ths, alp, scal), testW13) Campbel.nlis <-nlsList(y~SScamp(lnx, Ths, alp, scal)|Points, testW13) Campbel.nlme <-nlme(Campbel.nlis) # Estimate mixed-effects