Models according to which irrigation water can be allocated among areas were compared: The incremental benefit/ cost model, based upon a predetermined cropping pattern (as used by the Department of Water Affairs and based upon data of the Department of Agriculture and Water Supply), a linear programming model taking the same cropping pattern as given, and linear programming models in which crop selection and water allocation are optimized simultaneously. Results indicate that models aimed at simultaneous optimization yield results that are economically superior to models based on fixed cropping patterns.