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mehran mohamadi; javanshir azizi mobaser; Majid Raoof
Abstract
In order to know the technical status of the irrigation systems and determine the amount of achievement of the objectives of the design stage, it is necessary to evaluate these systems.In this study, 18 classic fixed sprinkler irrigation systems with mobile sprinklers implemented in different parts of ...
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In order to know the technical status of the irrigation systems and determine the amount of achievement of the objectives of the design stage, it is necessary to evaluate these systems.In this study, 18 classic fixed sprinkler irrigation systems with mobile sprinklers implemented in different parts of Ardabil plain in the summer of 2019 were evaluated. For this purpose, criteria such as Christiansen Uniformity Coefficient (CU), Distribution Uniformity (DU), Potential Application Efficiency of Low Quarter (PELQ),and Actual Application Efficiency of Low Quarter(AELQ),were used at both block and system scales.After measurements and collection of the required information, these criteria were calculated. The mean values of the criteria were for the blocks were 83.46%, 74.96%, 68.93% and 67.94%, respectively, and for the systems, they were82.32%, 73.43%, 65.71% and 66.70%, respectively. In addition, Wind Drift Losses (WDEL), Deep Percolation losses (DP) and irrigation adequacy (ADirr) were found to be, 7.95%, 6.97%and 27.08%, respectively. Results and field studies showed that low values of PELQ and AELQ were affected by inappropriate spacing of sprinklers, lower pressure compared to design pressure, high pressure changes in the system and simultaneous use of large number of sprinklers. In addition, inaccurate management in operation, land topography and long lengths of pipes are effective factors in reducing the actual performance indicators of irrigation systems in Ardabil plain. Among the suggested recommendations are a revision of the designs, due consideration of the land slope, change in the type of sprinklers, or even change in the orifice of the sprinklers.
Majid Raoof
Abstract
Many forces applied to soil surface during cultivation season cause soil compaction, which affects many soil physical and hydraulic parameters. Under field condition, different forces affect the soil and cause changes in its characteristics. The aim of this study was to determine the effect of soil compaction ...
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Many forces applied to soil surface during cultivation season cause soil compaction, which affects many soil physical and hydraulic parameters. Under field condition, different forces affect the soil and cause changes in its characteristics. The aim of this study was to determine the effect of soil compaction on soil physical and hydraulic properties. Four treatments including T0 (no tractor pass), T1 (one pass), T2 (three passes) and T3 (five passes), were selected. Treatments were irrigated regularly as local farmers’ schedule. After three months, soil samples were taken for determination of some soil properties such as particle and bulk density, shape of cumulative infiltration curve, soil moisture retention curve, and saturated and unsaturated hydraulic conductivity. Water infiltration rate was measured in each treatment using a double ring infiltrometer. Residual water content at a given water pressure head was obtained in laboratory. Inverse solution was used to estimate soil water retention and unsaturated hydraulic conductivity functions parameters by Hydrus 3D code. Results indicated that by increase in the number of tractor passes over the soil surface, bulk density of T1, T2 and T3 treatments increased by, respectively, 17.41%, 26.87% and 35.65% compared to T0. Total porosity of T1, T2 and T3 treatments decreased 16.55%, 25.36%, and 33.04 % and saturated hydraulic conductivity of the same treatments also decreased 38.09%, 59.05%, and 61.43 % compared to T0, respectively. Particle density was constant. Residual moisture, saturated , saturated,and van Genuchten increased, while and decreased due to increase of soil compaction. Soil compaction effect on, , , and parameters was significant, but the effect was insignificant on parameter. Significant probability of these five parameters is different.
Majid Raoof
Abstract
Speed and direction of wind affect water distribution pattern of sprinkler irrigation system. Based on an acceptable water distribution uniformity range, distribution pattern of any single sprinkler under different wind conditions is needed to determine the best sprinklers arrangement. In this study, ...
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Speed and direction of wind affect water distribution pattern of sprinkler irrigation system. Based on an acceptable water distribution uniformity range, distribution pattern of any single sprinkler under different wind conditions is needed to determine the best sprinklers arrangement. In this study, water distribution of NELSON-F80AP sprinkler was assumed to be a function of the Beta probability distribution and influences of wind speed and direction on the distribution pattern were studied. Similar to common sprinkler irrigation systems, a single sprinkler (NELSON-F80AP model) with wetting radius of 22.86 m and application angle of 360ο was set at about 1 m height from land surface. According to the operating pressure in the irrigation system, 40 psi pressure was applied during the experiments. Firstly, Beta distribution function parameters were calculated on the basis of the measured water distribution pattern under controlled (no wind) condition. Then, the change of distribution pattern due to different conditions of wind and its relevant suitable probability function parameters for each condition were determined. The water distribution pattern uniformity was fair and a good fitness between the calculated and observed data was obtained in the wind speed range of 0-3 m/s. The relative error was less than 3.53% in this case. In the speed range of 3-6 m/s, the distribution pattern uniformity was poor and the relative error was raised up to 4.65%. For the wind speeds greater than 6 m/s, relative error between the calculated and measured pattern was about 8.48%, because of wind drift and evaporation losses and also the effect of wind on the uniformity of water distribution pattern.