ABSTRACT
The irrigation district managers must plan early how available water should be used, given its large demand. It is known that a relationship between demand and water availability exists, because the crop patterns have the tendency to adjust to the water availability. The purpose of this research was to study the crop pattern for the Nilo Coelho, PE irrigation district, using a linear programming model. The linear programming technique has been widely used for representing this kind of production system, mainly for planning purposes in new areas or for improving the irrigation projects already in operation. The studied model is a traditional linear programming formulation, in which the objective function consisted into maximizing the net income of the project using the most cultivated crops in the area, under irrigation conditions. The restrictions to the objective function were the monthly and annual water volume, land and marketing. The maximization of profits in the colonization area of the Nilo Coelho project, given by the linear programming model, was equal to US$ 22,634.044, for the following crop pattern: beans (714 ha); watermelon (714 ha); green pepper (714 ha); tomato (428 ha); onion (357 ha); and banana (818 ha). The annual water availability presented an opportunity cost equal to 0.28 (US$.m-3) and was the strongest restriction, contrary to the monthly availabilities.
Key words:
linear programming; irrigation district; crop pattern