Document Type : Original Article
Authors
1 phd student, Water Engineering, Faculty of Agriculture & Natural Resourses, Imam Khomeini International University, Qazvin, Iran
2 Associate professor, Water Engineering, Faculty of Agriculture & Natural Resourses, Imam Khomeini International University, Qazvin, Iran
Abstract
Introduction
Pressurized irrigation systems are efficient tools to improve agricultural water productivity. However, the implementation and operation of pressurized irrigation systems require energy supply, related tools, and equipment, followed by greenhouse gas emissions. In this regard, one of the factors in the degradation of the environment is the phenomenon of global warming due to carbon dioxide emissions. The country's agricultural authorities have considered and invested in developing and implementing pressurized irrigation systems as one of the main approaches for proper water use. Due to the phenomenon of global warming, the primary source of which is greenhouse gas emissions. Any activity in the production of equipment, energy, and mechanization of irrigation systems leads to the production of greenhouse gases, increasing the air temperature and crop water requirements. If the irrigation systems are evaluated from an environmental point of view, air pollutants emissions can be considered an influential factor. This issue has been neglected in the country concerning systems evaluation.
Materials and methods
In the present study, drip irrigation systems implemented in Qazvin province during 2010-2020 were randomly selected and evaluated for energy flow and greenhouse gas emissions. In this research, 17 drip irrigation systems, including pistachio, apple, peach, and nectarine crops, were randomly selected and studied in terms of energy flow and emissions of greenhouse gases. According to the energy equivalent coefficients and carbon dioxide emissions coefficient, the total input energy and carbon dioxide emissions for the drip irrigation systems were calculated. In this research, after collecting data on the drip irrigation systems, we used drilling machines, welding equipment, and manpower based on the equivalent energy extracted from the sources for each stage of equal energy in terms of Megajoules. The process of implementation and operation of the irrigation system was calculated. Then we used greenhouse gas emission coefficients for three crucial greenhouse gases: carbon dioxide, nitrogen oxide, and methane, and considered the global warming potential of each gas using the relation that "i" is The amount of carbon dioxide equivalent to the emitted from the installation and operation of the drip system.
Results and discussion
The results showed that the total annual energy consumption and carbon dioxide greenhouse gas emissions in the evaluated irrigation systems averaged 36,2022.68 MJ per hectare and 1974.07 Kg/ha, respectively. It was found that the highest contribution of energy consumption and carbon dioxide emissions, with 85% and 86%, respectively, are related to the operation stage of the pumping station system. Besides, the production and transporting of the system equipment accounted for 13% of energy consumption and 10.93% of carbon dioxide emission. According to the results of the energy calculations and carbon dioxide emissions and considering the operating period of 15 years for the drip irrigation systems, energy consumption and carbon dioxide emission are 534,035 GJ/ha and 29.611 tons/ha, respectively. These values were calculated based on considering the processes of equipment supply, system installation, and the operation of the pumping station.
Conclusion
The findings of this study showed that the amount of energy consumed and carbon dioxide emissions in different stages of drip irrigation systems were very different. The energy consumption in the pumping station to provide the required working pressure had the largest impact. Energy consumption could be reduced by applying water consumption management, selecting pumps with higher efficiency, and avoiding imposing additional load on the network. On the other hand, due to the efficiency of electricity production in power plants in Iran and its efficiency of transmission and distribution, if the mentioned efficiencies were improved, the equivalent of energy consumption due to electricity consumption in the pumping stage would be reduced. Due to the topographic conditions and geometric shape of farms and their distance from factories producing equipment, energy consumption and subsequent carbon dioxide emissions for different farms will not be a fixed number. The impact of all practical steps except pumping energy consumption will be reduced annually.
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