. Model development
3.2.1. Objective
The objective is to maximize the total benefits through planning various
agricultural activities in consideration of trade offs 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
and sediment in runoff from agricultural activities degrade the
quality of the waterways, and result in soil erosion and environmental
deterioration (Mance, 2007). Therefore, it is desired by the decision
makers that non point source pollution from various agricultural activities
be controlled in order to sustainably develop the local economy.