Net irrigation requirement

NIR = sum over months of max(0, ETc_m - Peff_m) (mm). Compute monthly, then sum, as for green/blue water. Volume via wapor_zonal_stats().

Usage

wapor_calc_nir(etc_monthly, peff_monthly)

Source

Allen et al. (1998); Smith (1992) CROPWAT.

Arguments

etc_monthly

Monthly ETc, numeric vector, SpatRaster stack, or list of rasters.

peff_monthly

Monthly effective rainfall, same shape as etc_monthly.

Value

Numeric or SpatRaster (mm).