where kc is the average crop coefficient defined according to the land use pattern of each parcel, ETo(i) and Peff(i)
are the reference evapotranspiration and the effective rainfall of the i-th month, both in mm. The product kc by ETo is
the crop water requirement under standard conditions (Allen et al. 1998).
The parameter Peff (i.e. net of foliage interception) can be calculated for each month as (Brower et al. 1986):