OPTIMUM WATER ALLOCATION FOR THE AGRICULTURAL SECTOR IN SOUTH CENTRAL TEXAS

A model that optimizes agricultural water use to maximize profit subject to constraints of water and land availabilities, maximum satisfaction levels of highly profitable crops, and minimum satisfaction levels of low profitability crops was developed. This model is meant as a management tool at the basin and national levels. Both irrigated and rain fed agriculture, are considered. The model was implemented to South Central Texas Region which includes twenty counties. Corn, cotton, peanut, sorghum, soybeans, sesame and wheat in addition to forage were considered. Planted forage areas, both irrigated and rain fed, were imposed in order not to result in land use change. In addition, no introduction of new crops to any county is allowed. The model was run for three scenarios of different satisfaction levels and four scenarios of droughts coupled with constraints of different satisfaction levels. Three levels of droughts were simulated; mild, moderate and severe, which are associated with agricultural water shortages of 10%, 30% and 50% respectively. The results showed significant improvement in the objective function value as compared to the current cropping pattern for the scenarios that don't impose minimum satisfaction levels for low profitable crops, even when mild and moderate droughts are assumed. However, when minimum satisfaction level of 5% was imposed for low profitable crops, the results showed 11.9% reduction in profit. In addition, when this scenario is coupled with a mild drought, the result showed that the solution becomes infeasible.