بهينهسازي تجارت داخلي و خارجي آب مجازي محصول گندم در ايران

Optimization of domestic an‎d international virtual water trade of wheat in Iran

اقتصاد

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.

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