Normalises water consumption depths or water productivity indicators to remove the confounding effect of spatial climate variability (evaporative demand).
Usage
wapor_apply_climate_norm(x, f_norm, type = c("depth", "productivity"))Arguments
- x
Numeric or SpatRaster.
- f_norm
Factor from
wapor_calc_climate_norm().- type
"depth"or"productivity".
Details
Mathematical Derivation: With climate factor \(f_{norm} = \overline{RET} / RET\):
Depth indicators (AETI, ETc in mm): Multiplied by \(f_{norm}\). $$Depth_{norm} = Depth \times \frac{\overline{RET}}{RET}$$ Areas with higher evaporative demand (\(RET > \overline{RET}\), so \(f_{norm} < 1\)) have their consumed depth scaled downward to represent consumption under regional average demand.
Productivity indicators (CWP, BWP in kg/m3): Divided by \(f_{norm}\). Since \(WP = Yield / Depth\), normalising depth in the denominator yields: $$WP_{norm} = \frac{Yield}{Depth_{norm}} = \frac{Yield}{Depth \times f_{norm}} = \frac{WP}{f_{norm}} = WP \times \frac{RET}{\overline{RET}}$$ Under harsh, high-evaporative climates, plants inevitably consume more water per kg biomass produced, depressing unadjusted WP. Dividing by \(f_{norm}\) compensates for this climatic penalty, enabling fair comparison of agricultural performance across diverse agro-climatic zones.