نویسندگان
1 گروه علوم و مهندسی آب، دانشکده کشاورزی و منابع طبیعی، دانشگاه بین المللی امام خمینی(ره)، قزوین، ایران
2 گروه علوم و مهندسی آب/دانشگاه بین المللی امام خمینی
3 دانشیار گروه مهندسی آب، دانشگاه بین المللی امام خمینی (ره)
4 استادیادانشیار گروه مهندسی آب ، دانشگاه بین المللی امام خمینی (ره)ر
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and Objectives: Water shortage is the main challenge for agriculture in arid and semi-arid regions. Therefore, improving water productivity using different methods such as implementing pressurized irrigation systems is necessary. In these systems, efficiency and distribution coefficient are vital, simultaneously. The purpose of this study was to investigate the performance of flow control valves in regulating the volume of water delivered in the field and saving water consumption. A flow control valve is anticipated to deliver an almost constant flow for different pressure ranges.
Methodology: In this research, the performance of automatic flow control valves to adjust the water delivered in the field was investigated. For this purpose, two valves with flow rates of 5 and 10 L/s were installed on a farm equipped with a drip irrigation system to evaluate the effect of the valves in a field condition. The farm is located in Mahdiabad of Takestan. The area of this field is about 12 ha. Also, EPANET software was used to model the irrigation system in different scenarios. This software can simulate the behavior of water flows in pressurized networks. To model the irrigation system, the specifications of the reservoir, water transmission lines, manifold pipes, and laterals, which include the length, diameter of the pipes, and elevation, were given as the input characteristics of the program. Numerical models need to be calibrated to check the correspondence between the measured and simulated parameters. To compare the values measured and simulated by the EPANET model, statistical indices of root mean square error (RMSE), mean absolute error (MBE), and error percentage (NRMSE) were used.
Findings: First, the current condition of the farm was evaluated. The results showed the water discharges were 6.4 and 12.35 L/s for plots B and F on-farm, respectively. These discharges were 28% and 25.3% higher than the designed discharge for parts B and F, respectively. As a result, water consumption has increased and its surplus is removed as deep percolation or surface runoff. The flow control valves were then installed in a suitable place. After installing the flow control valves, the water delivery condition was re-evaluated. Discharges of B and F plots were 4.86 and 9.96 L/s, respectively. EPANET software was introduced to simulate the flow in the irrigation system. The results showed that the flow control valves could be used successfully to deliver an accurate volume of water to the plots and they could neutralize the effect of changes in pool water height or rupture of irrigation tapes. By investigating the effect of changing the height of the pool water, it was found that increasing the height of the water in the pool would result in increasing the irrigation system discharge. However, by installing the flow control valve, water delivery remained almost constant by changing the water height in the pool. Additionally, by examining the performance of the valve during rupture or dislocation of the irrigation tapes, the flow through the tested irrigation fields increased. However, with the use of flow control valves, due to the structural mechanism of them, the flow rate does not exceed the designed values. Also, the results showed that a dislocation or tearing in the irrigation tape by reducing the pressure would increase the amount of flow consumed by the irrigation system. However, the numerical modeling results showed that with the installation of the automatic control valve, the flow rate of the irrigation tapes was fixed in the suitable range.
Conclusions: Flow control valves deliver a semi-constant discharge irrespective of the pressure fluctuations. Experiments were performed to fabricate a suitable discharge control valve to improve water distribution uniformity in an actual field case. In this study, the effect of such a valve was investigated to adjust the water delivery. Field measurements revealed the successful application of the control valves on a farm scale. Also, numerical results indicated that the flow control valves could be used effectively to increase the flow uniformity with either water height fluctuations in the reservoir pool or the rupture of the irrigation tapes. In general, it was found that the flow control valve was a brilliant choice to increase water efficiency and uniformity in the field conditions. Numerical simulations must determine the location of the valves and their discharge characteristics.
کلیدواژه‌ها [English]
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