فهرست مطالب a. m. jafari

The virtual water trade concept was devised about three decades ago and it is now considered as a way of balancing the distribution of water among countries and regions in attempts to confront with water scarcity. The background literature of virtual water has developed independent of economic knowledge and economists have not endeavored to theorize it. Based on this concept, the export of agricultural products from Iran has been under much criticism in recent years. This study attempts to provide a simple economic model that works with based on opportunity cost theory in combination with economic water productivity and virtual water trade concepts to evaluate major agricultural products of Iran exported or imported in a five-year period. According to the results, internal production of strategic crops has high opportunity costs. The exporting of fruits such as kiwi, citrus, grapes, watermelon, cucumber and tomato created high virtual water values, even higher than pistachio. However, under the water crisis conditions in Iran, these values are much lower than real value of water.

Recent droughts and water crisis require the use of modern irrigation systems In order to properly use and increase the productivity of water resources. Therefore, this study was carried out to investigate the effect of two irrigation systems (Tape and Furrow Irrigation system) and different nitrogen levels (0,60,120 kg .ha-1) on yield, water use efficiency of garlic product at Ekbatan station, Hamedan Agricultural and Natural Resources Research Center. Experiment was laid out in a randomized complete block design arranged in a split plot with three replication. Two irrigation systems (Tape and Furrow Irrigation) were as main plot and different amount of N (0, 60, 120 kg.ha-1) were as sub plots. The results of analysis showed that effect of different irrigation system on yield and bulb weight wasn’t significant and the yield was equal in two irrigation systems approximately. The average of water productivity in two irrigation systems was 5.6 and 2.4 Kg. m-3. Water consumption in Tape irrigation relative to Furrow irrigation decreased about 54 %. The amount of water productivity in tape irrigation was increased about 103 percent relative to furrow irrigation. Respectively. The maximum of water productivity (4.27 kg/m3) related to 60 kg.ha-1 of N treatment. Considering that the cost-benefit ratio in two scenarios: increasing the area under cultivation and preservation of water resources was 2.84 and 2.54 respectively, therefore the use of drip irrigation system is economical for the garlic product.

In this article, the role of imports and exports of major agricultural products on amount of virtual water trade, net virtual water import (NVWI), and country water indices included water footprint (WF), water scarcity (WS), water dependency (WD), and water self-sufficiency (WSS) in agricultural sector was studied for a five-year period (1388- 1384). The results show that the volume of imported virtual water to Iran during the mentioned period for 16 major crops was three times more than the volume of exported virtual water for 16 major crops (about 125.8 and 37.9 billion cubic meters, respectively). This means that the NVWI in this period was positive. It is noted that sever increasing in positive NVWI in the two last years of this period has been accrued due to population increasing and drought events in most provinces of the country. Also, Annual meanly country water footprint in agricultural sector is 104.8 billion cubic meters in this period and with average annual 17.6 billion cubic meters through NVWI, Iran has been saved the same amount of its internal water resourecs. Calculated indices of WS, WD and WSS in Iran showed that the average annual intensity of water use in agricultural sector in the mentioned period has been 67.1% which is high (WS index close to 100). Average annual country's agricultural dependency on imports of virtual water (WD) has been 16.8%. This percentage indicates that if the country instead of importing agricultural products, produce those amount into country, an average of about 16.8% should be added to the water consumption in the agricultural sector. Also, average annual Iran's selfsufficiency to water (WSS) has been estimated about 83.2%.