3.2. Model development
3.2.1. Objective
The objective is to maximize the total benefits through planning various
agricultural activities in consideration of tradeoffs between multiple
environmental and economic criteria. The objective is equal to the total
revenue minus the total cost. Total revenue is derived from earnings of
paddy, dry and vegetable/fruit farms. For a watershed located in the
south-central China, the costs include expenses for surface and groundwater
supplies (e.g., pumping, allocation, and transportation) and those
where EV represents expected value. In the decision making, the best
way to reflect decision maker's preferences is to express them through
linguistic terms, establishing a semantic correspondence for the different
degrees of feasibility (Zadeh, 1978). Linguistic terms are encountered
in the practical process of data acquisition since human
subjective judgment is involved. Therefore, the decision maker can
choose the preferred credibility levels for constraints based on the linguistic
termscale advanced by Jimenez et al. (2007) (λ=1: completely
satisfied constraint (SC), λ=0.9: practically SC, λ=0.8: almost SC, λ=
0.7: very SC, λ = 0.6: quite SC, λ = 0.5: neither SC nor unsatisfied