چكيده لاتين
The optimal management of water resources has gained increasing importance with the intensification of water scarcity and the growing limitations on renewable water resources in Iran particularly in the agricultural sector as the largest consumer of water. Wheat, as a strategic crop in ensuring food security, has exerted considerable pressure on the country’s water resources. Optimizing domestic and international virtual water trade in wheat has emerged as a policy-relevant strategy to reduce water consumption and safeguard food security, considering climatic heterogeneity, the decline in groundwater reserves, and variation in wheat water requirements and water availability across provinces.
In this study, a multi-objective linear programming model was developed and implemented for all provinces of the country in 2023. The virtual water content of wheat was estimated using data on crop yield, net irrigation water requirements, and the NetWat software. The model comprised four objective functions: minimizing water consumption, maximizing profit, minimizing fertilizer and pesticide costs, and maximizing food security, all restricted by water, land and supply–demand balance constraints. The objective functions were normalized using the min–max method, and their weights were determined under six different scenarios, including expert-based weighting using the Analytic Hierarchy Process (AHP), national policy documents and extreme weighting scenarios. Finally, the model was solved using LINGO software. The flows and balance of domestic and international virtual water trade in wheat were calculated.
The results of the study indicated that under the status quo scenario, the national wheat self-sufficiency level was approximately 80%, and the volume of external virtual water imports at the national level amounted to 3100 million cubic meters. In the expert-opinion-based scenario, the level of food security decreased by 51% compared to the status quo while external virtual water imports increased by approximately 145% relative to the status quo. The results of the policy-document-based scenario and the maximum food security scenario showed that both the level of food security and the volume of external virtual water imports remained nearly unchanged, similar to the status quo. In the profit-maximization scenario, the level of food security reached about 65% and external virtual water imports increased by approximately 77% compared to the status quo. Moreover, domestic production and the level of self-sufficiency declined to nearly zero under the scenarios aimed at both maximizing reductions in water consumption and maximizing reduction of fertilizer and pesticide costs. Thus, the country’s entire demand was met through imports. Overall, given the capacity and potential of virtual water trade, these indicators should be carefully considered by policymakers in formulating cropping patterns and planning the import of agricultural products.
