Using programming methods, the two models of cropping structures suggested by the study were remarkably different. The first model considered water availability levels, while the second tried to optimize its use. As such, some cash crops were excluded from the second model as water extensive users, such as some kinds of fruits. Hence, the second type models expected net revenues and benefit-cost ratios dropped to nearly one-third the corresponding estimates of the first type, and about 10-20% higher than those of the actual cropping structures in average. Accordingly, encouraging farmers to adopt cropping patterns of rational water use would be in vain unless fortified by taxation tools and guidance toward efficient methods of cost reduction and/or yields promotion.