Fixed constraints

The maximization of fiscal profit is subject to various physical land-area and water availability factors. These can be categorized into four types of constraints: crop area limits, crop area synchronization constraints; crop water-use limits; and crop water-use synchronization constraints. These will now be defined in turn.

Crop-area limits

For any given cropping season, subarea and crop type; individual cropping areas must be greater than or equal to zero, and less than the total arable land available in that subarea:

Equation6

 

Crop-area synchronization

For any given cropping season, and subarea; the sum of all cropping areas (for each crop) in that subarea, must be less than or equal to the total arable land available in that subarea:

Equation7

 

Crop water-use limits

For any given cropping season, subarea and crop type; the total crop water-use for each type of crop must be greater than or equal to zero, and less than the total available water in that subarea for that season:

Equation8

 

In the model, crop water-use (per ha) shall be defined as the crop water-use factor (mm) minus the effective rainfall (mm) in that subarea, and converted to ML/ha:

Equation9

 

Crop water-use synchronization

For any given cropping season, and subarea; the sum of all crop water-use (for each crop) in that subarea, must be less than or equal to the total water available in that subarea for that season:

Equation10