Use of Water Footprint and Virtual Water to Determine the Optimal Cropping Pattern; Case Study: Ghaenat and Zirkoh Counties

Management of water consumption in arid and semi-arid regions in recent years has been considered a key issue in the field of water resources management. Zirkoh and Ghaenat counties are the hot spots of water consumption in the region. Water footprint and virtual water are critical indicators for water resources management. Therefore, the development of the cropping pattern with high water requirements has led to a negative water balance in the Ghaenat and Zirkoh counties. To prevent the negative consequences of this crisis, it is necessary to consider the restriction of cropping pattern with high water requirements in the region, as well as the assessment of water footprint and virtual water of agricultural products. Also, one of the strategies for managing and optimizing the consumption of water resources in the region is to determine the appropriate cropping pattern with regard to the local conditions. Therefore, this study has been conducted with the aim of calculating the components of water footprint and virtual water in the cropping patterns of Zirkoh and Ghaenat counties and determining the optimal cropping pattern for planting crops from the perspective of water footprint.

In this study, the amount of virtual water and green, blue, gray, and white water footprint for wheat, barley, potato, sugar beet, cotton, alfalfa, and saffron were calculated in the current cropping pattern and at multi-objective nonlinear programming (MOP) approach with the objectives of maximizing net profit and minimizing virtual water, green, blue, gray and white water footprint as the optimal cropping pattern in Ghaenat and Zirkoh counties. The study area was irrigated areas of Zirkoh and Ghaenat counties during 2017.

The results showed that the indices of virtual water and water footprint components in Zirkoh county were higher than Ghaenat county. Also, in two counties, the blue water footprint was more than the green water footprint and the results showed that a large amount of water resources in this area is spent on the production of cotton. In all studied crops, blue water footprint was more than other components of water footprint, which shows the reliance on surface and sub-surface water resources. The results also showed that the area under cultivation of potatoes, melons, and barley in the multi-objective pattern of Ghaenat and the area under cultivation of melons, sugar beets, potatoes, watermelons, alfalfa, and saffron increased compared to the current cropping pattern. Reduction of area under cultivation of cotton, alfalfa, watermelon in Ghaenat county and cotton, wheat and barley in Zirkoh county by 50% in the multi-objective crop pattern were other important results. By determining the optimal cropping pattern, the environmental effects of the agricultural sector on water resources could be reduced, so that the implementation of this pattern in the region reduced virtual water by 26%, blue water footprint by 4%, gray water footprint by 18% compared to the current cropping pattern.

According to the findings of this study, it is necessary to pay attention to the environmental objectives affecting water resources in optimizing cropping pattern. Using the proposed model, in addition to selecting the appropriate model and optimal use of water and land resources, to increase profits and reduce water and virtual water footprint, about 13 million cubic meters of water could be saved compared to the current cropping pattern in the region. Therefore, by implementing the optimal cropping pattern, in addition to reducing the environmental effects, the net income could be maximized of water consumed per cubic meter in the region, and by reducing water consumption, we can help achieve sustainable consumption of limited water resources in the region.