R/waterStress.R

In pik-piam/magpie4: MAgPIE outputs R package for MAgPIE version 4.x

#' @title waterStress
#'
#' @description calculates which areas are affected by water stress from water availability and water demand in MAgPIE.
#'              Water stress is calculated based on the proportion of water withdrawals to water availability.
#'              Thresholds based on World Resources Institute
#'              definition (https://www.wri.org/data/water-stress-country):
#'              Low stress: <10%
#'              Low-to-medium stress: 10-20%
#'              Medium to high stress: 20-40%
#'              High stress: 40-80%
#'              Extremely high stress: >80%
#'
#' @param gdx         GDX file
#' @param stressRatio threshold defining level of water stress
#'                    (e.g. 0.2 for medium water stress,
#'                    0.4 for high water stress)
#' @param file        a file name the output should be written to using write.magpie
#' @param level       spatial level of aggregation: "cell" (cellular), "reg" (regional),
#'                    "glo" (global), "regglo" (regional and global)
#'
#' @return MAgPIE object indicating whether location is water stressed (1) or not (0)
#'
#' @importFrom magclass getItems
#'
#' @export
#'
#' @author Felicitas Beier
#' @examples
#' \dontrun{
#' x <- waterStress(gdx)
#' }
#'
waterStress <- function(gdx, stressRatio = 0.4, file = NULL, level = "cell") {

  # ratio of withdrawals to availability
  scarcity <- waterStressRatio(gdx, level = level)

  out <- scarcity
  out[scarcity <= stressRatio] <- 0
  out[scarcity > stressRatio]  <- 1

  return(out)
}