Agricultural Water Use Management of Sistan Region under Virtual Water Approach Using WEAP Model

Agriculture is the largest user of freshwater in the world. One of the practical solutions for managing agricultural water resources in arid and semi-arid regions is to calculate the amount of water consumption in the process of agricultural crops through the virtual water index. The aim of this study was to use virtual water to manage water consumption in the agricultural sector of the Hirmand catchment. The need for irrigation of agricultural crops in the catchment was obtained using CROPWAT software. Then, the current and future status of water supply and demand was investigated using the WEAP model for agricultural crops in the catchment in the current cultivation pattern of the region. After calculating the virtual water content of the crops, the cultivation pattern was presented based on it and with emphasis on the need for irrigation. The water demand for crops in the virtual water scenario of the cultivation pattern was investigated using the WEAP model. The results showed that the need for irrigation of crops in the Hirmand catchment was 7847 m3/ha and the virtual water content of crops was 2.353 m3/kg. The agricultural sector consumes 70.10% of the total water supply in the Hirmand catchment. In the current situation, the total annual demand of water for crops is 1011×106 m3, of which 67.13% is supplied and 32.87% is not supplied. If the current situation continues for the next 15 years, the agricultural sector will face water shortages of 6099×106 m3. By applying the virtual water scenario, the demand for agricultural water could be decreased by 180×106 m3/yr. Finally, it was found that if the priority of water allocation between the agricultural sector and the drinking sector be the same, the drinking sector will face an annual water shortage of 18×106 m3.