Sustainable Conjunctive Use of Surface Water and Under Ground Water Resources Determining Optimal Cropping Patterns in Qazvin Basin

Surface water restriction and supply variation of these resources causes of over extraction of under ground water in Iran. There is unbalance between feed and extraction of under ground water. It causes water crisis، so we must pay attention to water resources to protect its sustainability. This paper use mathematical programming models to optimize the conjunctive use of surface and under ground water in agronomy production in Qazvin basin، one of the most important areas of water crisis. For this Purpose، linear programming model was used to determine optimal cropping patterns in Qazvin with maximizing net benefits and social benefits in 2007. In both scenarios، the suggested cropping patterns were corrected and adjusted according to different crops farmland and market constraints then the results were compared. The results showed that with considering under ground water resources restrictions، maximizing social benefits can create more profit. Extraction of under ground water resources distribution in each of the models estimated in the months of the year has been different. Distributed according to water requirement of selected products proposed planting pattern has changed.