R/InitialD.R

In CropWaterBalance: Climate Water Balance for Irrigation Purposes

#' Soil Water Deficit in the Root Zone
#'
#' Estimates initial values for soil water deficit.  Required to initiate the
#'  water balance accounting.
#'
#' @param teta_FC
#' Soil water content for the effective root zone at the field capacity
#'  \eqn{m3/m3}
#' @param teta_Obs
#' Soil water content for the effective root zone at the wilting point
#'  \eqn{m3/m3}
#' @param Drz
#' Vector, 1-column matrix or data frame defining the root zone depth in
#'  metres.
#' @return
#' Initial soil water deficit in the root zone (millimetres).
#' @export
#' @examples
#' teta_FC <- 0.30
#' teta_Obs <- 0.17
#' Drz <- 0.3048
#' Dinitial(teta_FC = teta_FC, teta_Obs = teta_Obs, Drz = Drz)
Dinitial <- function(teta_FC, teta_Obs, Drz) {
  pars <- list("teta_FC" = teta_FC, "teta_Obs" = teta_Obs, "Drz" = Drz)

  if (!all(unlist(lapply(pars, is.numeric))) ||
      any(unlist(lapply(pars, anyNA))) ||
      any(lapply(pars, length) != 1) ||
      any(pars < 0) ||
      teta_Obs > teta_FC) {
    stop(
      "Physically impossible or missing `teta_FC`, `teta_Obs` or `Drz` values.
         Also: `teta_Obs` cannot be larger than `teta_FC`."
    )
  }

  Dinitial <- 1000 * (pars$teta_FC - pars$teta_Obs) * pars$Drz
  return(Dinitial)
}