Original Article
Hydraulic
Kimia Akhavan; Manouchehr Heidarpour
Abstract
Extended AbstractIntroductionHydraulic jump is a type of rapidly varied flow in which the flow transitions from supercritical to subcritical. Incorporating rough beds at the channel bottom leads to the maximization of energy dissipation, resulting in a significant reduction in conjugate depth and ...
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Extended AbstractIntroductionHydraulic jump is a type of rapidly varied flow in which the flow transitions from supercritical to subcritical. Incorporating rough beds at the channel bottom leads to the maximization of energy dissipation, resulting in a significant reduction in conjugate depth and roller length. These results have important implications for the cost-effective design of stilling basins, which commonly encounter hydraulic jumps.one feature that has attracted the attention of researchers studying jumps on rough beds is the velocity profile of the jump on rough beds. In this research, the effect of the arrangement of submerged vanes on the velocity profiles of the hydraulic jump in a stilling basin was measured for Froude numbers ranging from 4.8 to 9.14.MethodologyExperiments were conducted in the hydraulic laboratory in a rectangular channel with physical dimensions of length 8 m, width 0.4 m, and height 0.6 m. Submerged vanes were used as roughness elements on the bed of the laboratory channel. These vanes are made of Teflon, and the geometry of a submerged vane, including its width (w), thickness (t), angle of attack (θ), and vane length (L), is one of the parameters affecting the characteristics of the hydraulic jump. For measuring the flow velocity, an instrument called a Pitot tube was used. In the present study, for 12 experimental models, velocity was measured at five cross-sections along the width, and at three points across the width in each cross-section. Measurements were taken at five points along the depth, with equal spacing ratios from the channel bed to the free water surface, and the readings were averaged across three different widths.Results and DiscussionIn general, the maximum velocity value decreases with distance from the beginning of the jump and occurs at a lower depth from the water surface. The bed with submerged vanes causes a reduction in the flow velocity magnitude, and its maximum value occurs at higher points compared to the classical jump. The significance of the non-dimensionalized velocity graphs lies in comparing the growth of the boundary layer across the cross-sections. The average value of δ/b is 0.62 and 0.72, and for 50 < x/D₁, the ratio δ/b lies above the average line. Due to the low effect of turbulence and secondary currents caused by the presence of submerged vanes, the boundary layer thickness is greater in regions of calm flow ( areas with lower velocity). At values less than 50, the ratio δ/b decreases compared to the average line. The results showed that the value of the non-dimensional boundary layer thickness parameter, δ/b, was 0.72, which was highest in the parallel arrangement of submerged vanes at an attack angle of 75° compared to angles of 45° and 90°. Meanwhile, this value was obtained in the butterfly arrangement with an attack angle of 45° and increased from 0.56 to 0.01 compared to what other researchers have obtained.Conclusions Therefore, the best characteristic for the non-dimensional boundary layer thickness parameter, δ/b, on artificial roughness was achieved with the butterfly arrangement and a 45° attack angle of the submerged vanes, which proved to be an influential factor. In contemporary hydraulic jump research, the use of advanced techniques, such as machine learning tools and numerical simulations using Computational Fluid Dynamics (CFD), is increasing. Simulating hydraulic jumps with CFD is a complex task and requires careful attention to turbulence modeling, grid accuracy, boundary conditions, and various other factors. It is essential to employ advanced techniques for comprehensive three-dimensional (3D) velocity and bed shear stress measurements. Conducting turbulence analysis will contribute to a more refined understanding of the underlying flow dynamics. Furthermore, the challenge of hydraulic jump stability on adverse slopes persists. Introducing roughness elements and sills can enhance hydraulic jump stability on adverse slopes. Investigating the potential effects of scale in such conditions is necessary.
Original Article
Pressurized Irrigation Systems
Samad Hosseinzadeh Ajirlou; Bijan Nazari; fariborz abbasi; Afshin Khorsand
Abstract
Extend AbstractIntouductionWater scarcity is one of the biggest challenges facing the agricultural sector in many parts of Iran, especially in arid and semi-arid regions. Increasing agricultural water productivity is not only a solution, but also an absolute necessity. Although solutions such as increasing ...
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Extend AbstractIntouductionWater scarcity is one of the biggest challenges facing the agricultural sector in many parts of Iran, especially in arid and semi-arid regions. Increasing agricultural water productivity is not only a solution, but also an absolute necessity. Although solutions such as increasing the area under cultivation and increasing yield per unit area, optimizing agricultural inputs, controlling population and optimizing consumption, and increasing imports have been proposed to address the challenge of food security, each of these cases has its own implementation limits (Nouri et al., 2023; Garofalo et al., 2025). Crop models are considered a valuable tool for the integrated simulation of processes affecting crop growth and for the evaluation of crop management options (Mabhaudhi et al., 2014; Wallach et al., 2019). Crop models that can accurately estimate various parameters of crop growth, soil water dynamics, crop water use and expected yield under different irrigation levels can also be a fundamental aid for the successful implementation of irrigation management practises with limited and full irrigation (Sandhu & Irmak, 2019). Therefore, the aim of this study was to calibrate and then evaluate the AquaCrop model to simulate the yield and water productivity of forage maize under furrow and tape irrigation in the arid and semi-arid regions of Iran (Alborz province). In addition, the ability of the model to simulate the yield potential of forage maize under agricultural management in the study fields was evaluated.MethodologyThe data required for this study was collected in 2016 on farms in the province of Alborz. The farms were visited in coordination with the management of the Agricultural Jihad and were examined and selected taking into account the parameters required for the study. Three farms were selected in the city of Karaj, one in the Seifabad district, one in the city of Hashtgerd and one in the village of Haji Abad. The farm in Karaj was divided into three different sections due to its larger area, different cultivation dates and different irrigation schedules. Since understanding the current situation is one of the most fundamental planning steps for evaluating and providing solutions to improve any system, this study was conducted in the form of field experiments and field farms with the aim of investigating and estimating the current status of irrigation water productivity under farmers' management, and the potential for growing forage maize in Alborz province. Water resources, the cultivated area, total irrigated land area, soil texture, soil salinity, and irrigation water salinity in each farm were investigated and measured. Additionally, some farm characteristics such as area, precise GPS location, irrigation method, irrigation water source, timing of water withdrawal and variations in withdrawal flow rate throughout the year, network type, and operator characteristics were recorded using compiled information recording forms. Results and discussionThe results for the average yield of fresh forage corn were 49.12 tons per hectare using furrow irrigation method and 60 tons per hectare using tape irrigation method. In furrow irrigation, the highest fresh crop yield was obtained at Karaj farm (2) with 60 tons per hectare and an irrigation water productivity of 6.61 kg/m³. The lowest yield was recorded at Karaj farm (3) with 35 tons per hectare, while the lowest irrigation water productivity was at Karaj farm (1) with 4.24 kg m-³. The highest irrigation water productivity, 13.4 kg m-³, was observed at Hajiabad farm using tape irrigation. Therefore, tape irrigation is recommended for optimal water resource utilization. The study also showed that the RMSE index was 2.44 tons per hectare, and the d-agreement index was 0.947, indicating the AquaCrop model's ability to simulate corn fresh weight accurately in the study area. There was a strong correlation between simulated and measured crop yield values, with a coefficient of determination of approximately 0.95. The relative error (RE) was 3.7%, which is considered acceptable.ConclusionThe results demonstrated that the AquaCrop model has a strong capability to analyze various management scenarios, predict performance under water-limited conditions, and optimize irrigation patterns. From a management perspective, the findings suggest that agricultural policies should shift focus from the "land productivity" index to the "water productivity" index. Additionally, providing practical training for farmers, promoting modern irrigation technologies, and utilizing simulation models like AquaCrop can play a crucial role in reducing water waste, enhancing crop yield, and ensuring sustainable production. Ultimately, implementing these strategies will not only improve water productivity but also serve as an effective step toward protecting water and soil resources and ensuring long-term food security.
Original Article
Pressurized Irrigation Systems
syeed Hassan mousavifazl
Abstract
Extend AbstractIntouductionDrip irrigation is recognized as one of the most efficient methods for irrigating orchards and vineyards in arid and semi-arid regions. This study investigated the effects of two irrigation methods, surface drip irrigation (DI) and subsurface drip irrigation (SDI), on yield, ...
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Extend AbstractIntouductionDrip irrigation is recognized as one of the most efficient methods for irrigating orchards and vineyards in arid and semi-arid regions. This study investigated the effects of two irrigation methods, surface drip irrigation (DI) and subsurface drip irrigation (SDI), on yield, water productivity, growth parameters, and weed development in grapevines. The research was conducted in 2020 and 2021 at the Research Station of Bastam, Semnan Agricultural and Natural Resources Research and Education Center, Shahroud, Iran. Materials and MethodsThe study was designed with two factors: irrigation method (surface and subsurface) and different irrigation water amounts (50%, 75%, and 100% of the plant’s water requirement). A split-plot experiment based on a randomized complete block design with three replications was carried out. In the surface drip irrigation method, lateral pipes were placed 50 cm far from the tree trunk on the soil surface, while in the subsurface drip irrigation method, the lateral pipes were placed 50 cm far from the tree trunk and at a depth of 40 cm under the soil. Irrigation water was calculated using the Penman-Monteith method, and plants received irrigation every 3 days based on the designated water levels. The study examined the effects of experimental factors on crop yield, water productivity and growth characteristics of trees including the longitudinal growth of branches and their diameter were investigated in different treatments. ResultsThe results showed that the effects of irrigation method and irrigation water amount, as well as their interaction effects, on fruit yield were significant at the 5% level. The effect of irrigation method on weed growth was also significant; however, the individual effect of irrigation water amount and its interaction with irrigation method did not significantly affect weed growth. The maximum fruit yield was obtained from the subsurface drip irrigation treatment combined with 75% and 100% of crop water requirement (51,600 and 53,080 kg ha⁻¹, respectively). The yield difference between these two treatments was not statistically significant. The yield difference between subsurface drip irrigation and surface drip irrigation methods was approximately 12%. This indicates that a portion of the water applied to the orchard is lost through surface evaporation and is also used by weeds. ConclusionConsidering the performance of the treatments and the need to conserve water, the subsurface drip irrigation method with 75% irrigation water is recommended as the best treatment for grape orchards. This method ensures higher water use efficiency and reduced weed growth, while maintaining an adequate crop yield.
Original Article
Pressurized Irrigation Systems
Nader Naderi
Abstract
Extend Abstract
Introduction
In order to increase water productivity, the use of modern methods of pressurized irrigation is one of the effective solutions. These methods can play an important role in conserving water resources by reducing water losses, increasing irrigation efficiency and allowing ...
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Extend Abstract
Introduction
In order to increase water productivity, the use of modern methods of pressurized irrigation is one of the effective solutions. These methods can play an important role in conserving water resources by reducing water losses, increasing irrigation efficiency and allowing more accurate management of time and amount of applied water. Sprinkler irrigation is one of the suitable options for wheat fields in semi - arid regions. The Rain flat sprinkler irrigation system as a relatively new sprinkler method, requires less work pressure than conventional sprinkler methods and therefore energy consumption decreases. In addition, installation and operation of this system is simpler and faster and can be an appropriate option for irrigation management in water deficit conditions. Therefore, due to the limited water resources in Semnan province and the importance of wheat production and also for introducing the Rain flat sprinkler irrigation system, this study was conducted to investigate the effect of irrigation interval and different levels of water supply on yield and yield components of wheat.
Methodology
The aim of this study was to investigate the effect of irrigation interval and different water levels on yield and yield components of wheat in Rain flat sprinkler irrigation method for two years. The experiment was conducted as a split plot in randomized complete block design with three replications in Shahrud Agricultural Research and Education Center. Three irrigation intervals (4, 5 and 6 days) were allocated to main plots and three irrigation levels (100 ,80 and 60 %) in sub plots. Sprinkler irrigation pipes were placed at 4-meter intervals between planting rows. The length of planting rows was 8m. By using the Penman - Monteith method, water requirement of the plant was determined. At the end of growing season, wheat was harvested and yield was measured in each plot. Yield components including plant height, thousand grain weight and grains number per spike were determined for all treatments. Harvest index was calculated from the division of seed weight to total weight of vegetative and reproductive organs.
Results and Discussion
Results showed that the highest grain yield was achieved in irrigation interval of 4 and 5 days whereas irrigation interval of 6 days decreased yield. The effects of water supply, the treatments of 100 % and 80 % water supply had the highest yield and the 60 % water supply had the lowest yield. Therefore, it is possible to reduce water supply from 100 to 80 percent without significant reduction of yield, but decreases from 80 to 60 percent decrease grain yield by 39.17%. The interaction of interval and water supply showed that 4 days with 100 % water, 4 days with 80 % water and 5 days with 100 % water had the highest yield. The lowest yield belonged to 6 days with 60 % water, indicating a decrease of up to 60.35 % in adverse irrigation management. The highest plant height, grains number per spike and thousand grain weight was obtained in 4 days irrigation interval, but there was no significant difference between 4 and 5 days in grain yield and harvest index. Also, plant height, grains number per spike, thousand grain weight and harvest index were in the treatment 100 and 80 percent of water supply in the top group, while reducing water supply to 60 percent reduced the yield and its components significantly. The results show that in Rain flat sprinkler irrigation system, with appropriate management of irrigation interval and irrigation interval equal to 5 days and supplying 80 % water requirement, both yield and yield components can be maintained in desirable condition, while increasing irrigation interval or severe water reduction, both lead to significant decrease in yield and yield components.
Conclusions
The results of combined analysis showed that irrigation interval and its combined effect with water supply level had a significant effect on most of traits. The highest plant height, grains number per spike and thousand grain weight was recorded in 4 days irrigation interval, but there was no significant difference between 4 and 5 days in grain yield and harvest index. Also, plant height, grains number per spike, thousand grain weight, grain yield and harvest index were in 100% and 80% water supply in a statistical group, while reducing water supply to 60% reduced grain yield by 17.39%. Based on results, irrigation interval of 4 and 5 days with 80% water supply was the most suitable management to maintain wheat yield by reducing water use. The results of this study indicate that optimal water management in wheat cultivation can be achieved without yield reduction by reducing irrigation water by 20 percent and adopting a 5-day irrigation interval.
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