Single Sprinkler Research Articles

Study on the irrigation uniformity of impact sprinkler under low pressure with and without aeration

The distribution of water deteriorates when the operating pressure of an impact sprinkler (IS) decreases to some level. The aeration jet method is utilized to form an aeration impact sprinkler (AIS), aiming to improve the uniformity of water distribution under low pressure. Based on the structures of a 20PY2 impact sprinkler, an IS and AIS with the same sprinkler discharge were studied under operating pressures range between 150 and 250 kPa. A square test zone was formed by the four sprinklers, and the combined irrigation experiment was conducted under windless conditions. The results showed that the water loss ranged from 3% to 9.5% in all 18 test schemes. The coefficient of uniformity (CU) and distribution uniformity (DU) were used to quantify the degree of uniformity. The AIS had an approximately 3%–7% greater CU than the IS, which resulted in the CU reaching the specified value in the IS standard when the sprinkler functioned under low operating pressure. A linear relationship was found between the CU and DUlq. The uniformity of water distribution clearly changed with the operating pressure (150 kPa, 200 kPa, and 250 kPa) but decreased slightly with the increase in combination spacing (1 R, 1.1 R, and 1.2 R). In addition, the results of field experiment were compared with those of the simulation developed from a single sprinkler indoor experiment based on the water distribution radial curve. The simulated coefficient of uniformity was highly consistent with the experimental data and had an error of <7%. A sprinkler water jet with the aeration method was proven to be a feasible solution to reduce the operating pressure.

Comparison of an Innovative Mobile Strip Irrigation System with Full-Area Sprinkler Watering

Highlights Innovative stripwise irrigation directs water only to ridge crests, not furrows. Mobile strip irrigation saved 51% of the carrot water requirements. The uniformity coefficient of the irrigation above the ridges was high. No significant differences in the carrot yield were verified between the irrigation systems. The water use efficiency was higher for the mobile strip irrigation system. ABSTRACT. Irrigation plays an important role in agriculture in temperate regions because of the reduction in rainfall frequency during the spring and summer months along with the increase in average temperature and evapotranspiration. To increase irrigation efficiency, we developed an innovative mobile strip irrigation system for ridge culture. The objective of this pilot study was to compare the new technology with a standard full-area sprinkler system and analyze the yield, flow rate, applied irrigation on the ridges, and variability of the irrigation depths expressed by the Christiansen uniformity coefficient (CUC) and distribution uniformity coefficient (CUD). The experimental design applied the two treatments to carrots grown on eight ridges covering an area of 210 m2. The experiment was conducted at the University of Kassel, Witzenhausen, Germany. The results showed a flow rate ranging from 54.7 to 72.7 l h–1. Good CUC (89%) and excellent CUD (82%) were obtained for the mobile irrigation system, indicating low variability of irrigation depths. The water content in the ridge crest increased to field capacity after irrigation, with a moderate coefficient of variation (14%) among the measurements. In addition, water use reduction with respect to the standard irrigation system of 51% during the treatments, or 29% considering the entire experiment time, was observed, and no significant differences in the total fresh yield between the irrigation systems were verified. Because only a single sprinkler irrigation system with an irrigation efficiency of 80% was used, care must be taken when extrapolating the findings of the present study. High irrigation efficiency sprinkler irrigation systems with multiple sprinklers, which reduce the sprinkler irrigation amount, can be considered in future studies to confirm the increased water usage efficiency of the mobile strip irrigation system. Keywords: Carrots cultivation, Irrigation, Ridge agriculture, Water content, Water distribution, Water saving.

Two-dimensional spatial distribution modeling of sprinkler irrigation

Irrigation can provide significant agronomic and financial returns on agricultural activity. The maximization of the benefits obtained from irrigation depends, among other factors, on the water use efficiency, which is intrinsically related to application uniformity. For the sprinkler method, the irrigation uniformity assessment is based on results of labor-intensive field tests in which the two-dimensional water distribution pattern is measured in a grid of catch cans. The aim of this study was to evaluate a simplified methodology for determining the irrigation uniformity using water depth distribution data of a single sprinkler head in operation, positioned at the intersection of two diagonal alignments containing regularly spaced catch cans. Three methods to simulate the spatial water distribution on the alignments were evaluated: linear interpolation (LI), cubic spline (SC) and second-degree polynomial regression (PR). Each of these methods were associated with a procedure to calculate the two-dimensional spatial water distribution. The adequacy of the LI and SC modeling methods was verified by using the Wilcoxon-Mann-Whitney test (p-value < 0.05) applied to the data of the field tests. Mean values of the coefficient of efficiency equals to 0.771 and 0.785 were obtained for the LI and SC methods, respectively. The PR method underperformed the others.

Моделирование процессов фильтрации технологических растворов при блочном подземном выщелачивании

PAO “Priargunsky Production Mining and Chemical Association” has been working on reserves of uranium deposits of the Streltsovsky ore field for more than 50 years. During this period, most of the rich ores have been worked out by traditional mining and physical technology. The share of poor and ordinary ores remains significant, but traditional technology does not provide the necessary level of profitability. Therefore, the widespread introduction of physicochemical technology: underground block (BPV) and heap leaching (KV) can be a decisive moment in the continuation of the operation of these deposits. The applied technology of underground block leaching has one significant drawback – a low rate of uranium recovery into a productive solution, which significantly reduces the effectiveness of this technology in the development of poor uranium deposits. To increase the yield of uranium into the productive solution, it is necessary to analyze the entire preparation and leaching process and establish the main reasons for the low rates of transition of uranium to a mobile state. For this purpose, it is proposed to simulate the underground leaching process by building visual models of halos spreading of solutions along shrinked ore mining mass accumulated in an underground chamber. During the simulation, it was found that the distribution of the size classes of the broken ore pieces in the chamber can be predicted at the stage of drilling and blasting operations, and when determining the line of least resistance W and the distance between the ends of the wells, take into account the diameter of the controlled crushing zone R_p. At the same time, 3 zones of granulometric compositions are formed: a re-grinding zone, an optimum zone and a non-carbarite exit zone. The flow of solutions through these zones will differ the more significantly, the higher the height of the chamber. In a zone with larger crushing, an almost steep distribution of the solution spreading front is expected. Accordingly, the smaller the fraction, the lower the front to the horizontal is. The following functions are offered to simulate filtering processes: – it is possible to control the flow of working solutions to the fan of irrigation wells in order to achieve optimal leaching parameters, i.e. to quickly control the process; – knowledge of the law of distribution of irrigation flares makes it possible to select the optimal grid of location of single sprinklers

Analysis of Droplet Characteristics and Kinetic Energy Distribution for Fixed Spray Plate Sprinkler at Low Working Pressure

HighlightsAn experiment was conducted to investigate the hydraulic performance of a fixed spray plate sprinkler (FSPS).A model was developed for estimating the cumulative kinetic energy of the FSPS under a moving system.The droplet characteristics and kinetic energy distribution were affected by the working pressure and FSPS structure.A high cumulative kinetic energy could lead to a low water infiltration rate into the soil.Abstract. The kinetic energy of droplets from a fixed spray plate sprinkler (FSPS) has a substantial influence on runoff and soil erosion, as well as on the energy consumption of moving sprinkler irrigation systems. To determine the droplet characteristics and kinetic energy of an FSPS, an experiment was conducted to investigate the effects of working pressure, plate structure, and nozzle size on the droplet diameter, velocity, and kinetic energy. Two plates (the FSPSB with a concave trajectory and deep grooves in the blue plate, and the FSPSY with a flat trajectory and shallow grooves in the yellow plate) were used in the tests. The cumulative kinetic energy and water depth were calculated for a single sprinkler moving in a straight line. The results show that the FSPSB, which had deeper grooves in the plate, produced a larger droplet diameter than the FSPSY, with shallow grooves in the plate. The droplet landing velocities presented a logarithmic relationship with the droplet diameter, and velocities increased with an increase in droplet diameter. The peak specific power (SP) value of the FSPSB was 1.14 to 16.76 times that of the FSPSY. When the working pressure was less than 150 kPa, the peak SP of the FSPSB remained at a high level. With an increase in working pressure, the peak SP of the FSPSB initially increased and then decreased, while the peak SP of the FSPSY increased. The cumulative kinetic energy of the FSPSB was higher than that of the FSPSY under mobile spray conditions. Compared with the cumulative water depth, the cumulative kinetic energy of the FSPSB increased and then decreased as the working pressure increased for the same applied water volume. Because the soil had a lower infiltration rate under the FSPSB, surface ponding was more likely to occur with the FSPSB than with the FSPSY at low working pressure. Keywords: Cumulative kinetic energy, Droplet size, Specific power, Sprinkler irrigation, Working condition.

Empirical Equations for Estimation of Water Distribution Uniformity Coefficient in Case of the Alternate Setting of Sprinkler Laterals

Among the operating and management practices that can increase the uniformity of water distribution in the portable sprinkler irrigation systems is the alternate setting of sprinkler laterals. Shifting the laterals by half the distance between laterals results in a single alternate set and shifting the laterals by half the distance between the sprinklers results in double alternate set. Data representing 66 patterns of water distribution for a single sprinkler of different types of sprinkler heads were used. By choosing many suitable sprinklers spacing and using Microsoft Excel to implement the field distribution that free of dry spots, the following coefficients were computed: uniformity coefficient, uniformity coefficient of single and double alternate set, distribution uniformity, distribution uniformity of single and double alternate set and coefficients related to sprinklers spacing. Then, using the nonlinear regression analysis provided in SPSS, empirical relationships were derived to estimate both the single and double uniformity coefficients and the single and double distribution uniformity with determination coefficients of 0.783, 0.810, 0.720, and 0.766, respectively. The spacing coefficients that lead to the maximum values ​​of the different uniformity coefficients were determined based on inferred equations. In addition, the functions proposed in previous studies used in estimating the single and double uniformity coefficients with determination coefficients of 0.608 and 0.539, respectively as well as the single and double distribution uniformity coefficients with determination coefficients of 0.584 and 0.491, respectively showed low accuracy as compared with the ones proposed in the current study.

Study on the effectiveness of fire suppression deluge systems in tunnels

The required water flow for adequate deluge system operation during a tunnel fire is currently only prescribed by a few regulatory authorities. Car fires are commonly used as references when addressing water-based suppression; nevertheless, limited public information exists on the amount of water required for correctly suppressing a car fire and the thresholds by which the suppression systems fails to be effective. This paper aims at delivering key experimental outcomes to fill this gap in car tunnel fire suppression. The effectiveness of deluge sprinkler systems was investigated by performing a series of full-scale car fire experiments. These experiments were performed by symmetrically positioning a single car under a single sprinkler nozzle, with activation happening (i.e. the sprinkler going off) at a certain time from ignition (which defines the size of the fire), and carefully gauging the burning behaviour of the car fire. A single car was used as it was deemed as the minimum unit for a fire. Temperatures inside, around, and above the car were measured and infrared camera footage was used to gauge flame heights during the experiment. Results from this study yielded two forms of car fire suppression by a deluge system: gradual and instantaneous. A correlation between heat release rate and required water flow for the deluge system is also presented. Outcomes herein show that a water flow per unit area of 6.6 mm/min is the minimum water flow required to effectively reduce the temperature in the immediate vicinity of a car fire of different sizes.

Effect of Nozzle Angel &amp; Cyclic Pressure Head Variation on Water Distribution Uniformity for Stationary Sprinkler Systems

The present research included studying the effect of the sprinkler nozzle angle and cyclic variation of the operating pressure head on the uniformity of water distribution for many sprinkler heads spacing with rectangular and triangular sprinkler heads arrangement for different sprinkler heads. The research conducted 40 tests to measure a single sprinkler water distribution pattern under similar climatic operating conditions by adopting the water distribution pattern along a beam that represents the radius of the wetting circle which its center is a sprinkler head for different sprinkler nozzle angles (Ɵ + 5 °, Ɵ + 3.5 °, Ɵ, Ɵ -3.5 °, Ɵ -5 °) and the constant-cyclic operating pressure head conditions for different sprinkler heads. 320 patterns were found for field water distribution pattern and uniformity coefficient for four different spacing with a rectangular and triangular sprinkler heads arrangement for the sprinkler heads and the measured water distribution patterns. The research revealed that 70% of the uniformity coefficients in the rectangular arrangement are greater or equal to its value in a triangular arrangement. The increase in the nozzle angle results in increasing the uniformity coefficient of 1.4% for each degree, an increase in the nozzle angle, and can reach 2.4% for each degree for a specific spacing, arrangement, and sprinkler head. Also, the difference between the two water distribution patterns in the case of operating with constant pressure head and variable pressure head is slight, but it shows in the values of the uniformity coefficient, where the maximum difference reaches 10%, and in general, the best in the values of the uniformity coefficient requires determining the nozzle angle, the spacing and the arrangement of sprinkler head as well as the case of operating pressure head constant or variable.

Effect of Pulsating Pressure on Water Distribution and Application Uniformity for Sprinkler Irrigation on Sloping Land

Crops are highly susceptible to drought in sloping land. Due to its good adaptability to complex terrain, sprinkler irrigation is one of the commonly used methods for sloping land. To improve water application uniformity for sprinkler irrigation on sloping land, an experiment was conducted on an artificial slope to determine the effects of pulsating versus constant pressure on sprinkler flow rate, radius of throw, water distribution pattern, and water application uniformity. Compared with sprinkler flow rate and water distribution uniformity at constant pressure, sprinkler flow rate was not reduced, but water distribution uniformity for a single sprinkler was improved due to the decreased uphill throw, downhill throw and the ratio of downhill throw to uphill throw at pulsating pressure. The Christiansen Uniformity Coefficient (CU) value of water distribution for a single sprinkler at pulsating pressure was about 10% higher than that of constant pressure. When water distribution of single sprinkler overlapped with rectangular arrangement, CU values for pulsating pressure were on average 4.06% higher than those for constant pressure with different sprinkler spacings. Thus, pulsating pressure is recommended for use in sprinkler irrigation on sloping land to improve water application uniformity.

Effects of Operating Pressure, Nozzle Diameter and Wind Speed on the Performance of Sprinkler in Irrigation System during Water Application

Owing to an increasing demand for irrigation water associated with the massive expansion of irrigated sugarcane farms in Ethiopia, there is a need to use the available water efficiently and effectively. Accordingly, a study was conducted to evaluate the effect of operating pressure and nozzle size on the field performance of dragline sprinkler system at Wonji/Shoa Sugar Estate. The study was conducted under three wind phases (morning, mid-day and late afternoon) using three operating pressures (250 kPa, 300 kPa and 350 kPa) and two nozzle sizes (4.4 and 4.8 mm). Uniformity measurements were performed using single sprinkler and four sprinklers configurations. An application efficiency of low-quarter of 41% to 80.3% and actual application efficiency of low-quarter of 30.1% to 37.5% were achieved under the respective test combinations. Christiansen’s coefficient of uniformity of 71.7% to 86.3%, and distribution uniformity of 61% to 80.3% were achieved under different test combinations for four sprinklers test. The achievable delivery performance ratio was in the range of 0.81 to 1.18. The experimental results illustrated that, lower operating pressure and higher wind velocity were the major factors responsible for the low water distribution uniformity and efficiency. &#x0D; &#x0D; &#x0D; &#x0D;

Estimation of wind drift and evaporation losses in sprinkler irrigation of urban green spaces

The wind drift and evaporation losses (WDEL) are high in arid, semi-arid and windward areas, and reduce the efficiency of the sprinkler irrigation system; therefore, this study was carried out in order to achieve a practical criterion and provide a relationship for accurate estimation of the wind drift and evaporation losses in different atmospheric conditions. The experiments were done at the Meteorological Station of the Faculty of Agriculture of Ferdowsi University of Mashhad using a line-source sprinkler irrigation system based on the single sprinkler installation method. To achieve the objectives of this plan, factorial experiment was performed on PGP sprinkler with regard to the two factors, the pressure of the sprinkler function (with three levels 1.6, 2.5 and 3.4 bar) and the diameter of the nozzle (with three levels of 4, 5 and 6 mm) with three replications (morning, noon and night). Assessing the result of the data variance analysis showed that the effects of pressure, aperture diameter, and time on the wind drift and evaporation losses are not significant. Investigating the main effects of these factors showed that the effect of aperture diameter on irrigation losses is significant at the level of the 1%. In order to further investigate, the comparison of mean losses data in three aperture diameter was done using Duncan′s test. The results indicated that aperture 4 with the losses of 44% had a significant difference with other diameters. This result suggests an increase in losses for smaller diameters due to the small droplets and the increase in wind drift. Also, the comparison of the mean losses data in three times showed that irrigation at noon with the losses of 44% had a significant difference compared to other times due to a significant increase in temperature and radiation of the sun and saturation vapor pressure deficit, and there is no significant difference between morning and evening irrigation. Also, analysis of variance showed that the effect of water pressure change between 1.6 and 4.3 bar does not have a significant effect on the WDEL in this sprinkler. In general, the results showed that increasing wind speed increases the losses of evaporation and wind. Also, this study suggested that changing the irrigation time in areas with hot and dry days, from day to night in summer, leads to a significant reduction of the wind drift and evaporation losses.

Computer Simulation for the Process of Overlapping Solid Sets of Sprinkler Irrigation Using Single Sprinkler Data.

Computer Simulation for the Process of Overlapping Solid Sets of Sprinkler Irrigation Using Single Sprinkler Data.

Test methods for characterising the water distribution from irrigation sprinklers: Design, evaluation and uncertainty analysis of an automated system

An automated system for indoor testing of irrigation sprinklers was developed and evaluated. The system was designed to test single sprinklers with jet lengths up to 18 m. The tests involve the use of 36 collectors (catch-cans) spaced at 0.5 m intervals along the jet radius. A single pressure transducer coupled to a manifold equipped with solenoid valves was employed to sequentially scan the water level in each collector. Radial application rates were determined based on water level measurements. Results obtained using the automated system were compared with those obtained using manual operation using mass measurements. Uncertainty analysis of the manual method was compared with the automated system. The automated system was found to be as reliable as the manually operated system for testing sprinklers. Although minor differences in the application rates measured by the two methods were detected, they did not cause appreciable differences in the distribution uniformity indicators used. The results presented will provide useful baseline for uncertainty analysis in irrigation sprinkler testing.

Performance Evaluation of Infield Sprinkler Irrigation System under Existing Condition in Beles Sugar Development Project, Ethiopia

In Beles Sugar Development Project sugar cane fields was faced poor irrigation water management that under watering in most fields, dry spot and over watering in rare fields were observed. Therefore, the main objective of this study was evaluating the performance of infield sprinkler irrigation system under existing condition. The actual water application uniformity was measured for single and four overlapping sprinklers by installing catch can at a grid spacing of 3 × 3 m with two replications at hydrant pressure of 2.5 and 3.0 bars. The performance parameters analyzed were, uniformity coefficient (CU), distribution uniformity (DU), and system uniformity, pressure and discharge variation along laterals also analyzed. The average actual DU and CU obtained at 3 and 2.5 bars at existing sprinkler spacing of 18 m ×18 m was 53% and 63% respectively. The value of CU was lower than the recommended value of 75%. In order to determine alternate sprinkler spacing’s under existing working condition, the catch can data for single sprinkler were overlapped for different spacing’s whereas respective DU and CU were estimated. For both 2.5 and 3 bar operating pressure; 12 × 18 m, 12 × 12 m, 18 × 12 and 9 × 12 m sprinkler spacing’s were in between good and excellent acceptable range. Keeping in view economy, wider spacing, 12 × 12 m is recommended to have excellent water distribution with CU equal to 85% and 87% at operating pressure of 2.5 bar and 3.0 bar respectively. The actual average sprinkler discharge variation along laterals was above and out of the range accepted value up to 10%, whereas the actual average pressure variation along laterals is within the accepted range value of 20% but in some field laterals other than the test area, the variation was above the accepted range value of up to 20%.

Analysis of Water Distribution Uniformity for Two Types of Sprinklers used in Sprinkler Irrigation Systems under Various Climatic and Hydraulic Conditions

In order to increase the distribution uniformity of sprinkler irrigation systems, some influential parameters such as wind speed, arrangement, space and type of sprinklers must be studied and controlled. In this study, a set of experiments were conducted based on ISO 7749/2(1990) standard to evaluate the ADF 25 0 and Nelson, F80APV sprinklers. To study the effects of wind velocity, operating pressure, various sprinkler layouts and spacing on water distribution uniformity, the experiments were conducted based on a single sprinkler method. Four operating pressures in the range of one recommended by the manufacturer for each sprinkler were applied and three sprinklers’ spaces on lateral pipelines (22, 26, and 30 m) were simulated for square and rectangular layouts to estimate the water distribution uniformity. Results showed that the distribution uniformity of Nelson sprinkler in existing wind velocities and operating pressures had smaller changes than ADF sprinkler. The 4.5 bar pressure for ADF sprinkler was better than other pressures, and operating pressures for Nelson sprinkler did not have any significant effect on distribution uniformity. With the decrease of sprinkler spacing to the wetting diameter in the simulated space, uniformity coefficient was increased. The recommended sprinkler spacing to the wetting diameter for these sprinklers ranged from 0.4 to 0.5 for square and rectangular layouts.

Analysis of water application with semi-portable big size sprinkler irrigation systems in semi-arid areas

Sustainability of irrigated agriculture depends heavily on getting a high efficiency application for the irrigation. It is very important to understand the factors that affect to irrigation uniformity and discharge efficiency, especially using semi-portable big size sprinkler. There are not studies conducted with big size sprinklers which work on high flow rates and big layouts spacing. In this paper, the spray losses (Ls) and water distribution of sprinkler irrigation system with semi-portable big size sprinkler on semi-arid areas have been characterized. The factors affecting on discharge efficiency and irrigation uniformity were analysed (working pressure, irrigation layout and weather conditions). The field tests were conducted in outdoor conditions with a single sprinkler system. Six predictive equations were obtained to estimate drift and evaporation losses. The proposed equations use operating pressure, wind speed and vapour pressure deficit. The results show an increment of 3.26% for Ls for each increment of 1ms−1 of wind speed. Spray losses rise up to 22.7% at 450kPa operating pressure when wind speed and vapour pressure deficit increased up to 4.2ms−1 and 6kPa, respectively. A significantly effect of wind is appreciated on the spray losses and water distribution pattern under different conditions with regard for working pressure and sprinkler spacing. This behaviour is very similar to obtained with medium size sprinklers. Technical criteria can be used to optimize irrigation management according to the design factors and the climatic parameters.

Artificial neural networks for simulating wind effects on sprinkler distribution patterns

A new approach based on Artificial Neural Networks (ANNs) is presented to simulate the effects of wind on the distribution pattern of a single sprinkler under a center pivot or block irrigation system. Field experiments were performed under various wind conditions (speed and direction). An experimental data from different distribution patterns using a Nelson R3000 Rotator® sprinkler have been split into three and used for model training, validation and testing. Parameters affecting the distribution pattern were defined. To find an optimal structure, various networks with different architectures have been trained using an Early Stopping method. The selected structure produced R2= 0.929 and RMSE = 6.69 mL for the test subset, consisting of a Multi-Layer Perceptron (MLP) neural network with a backpropagation training algorithm; two hidden layers (twenty neurons in the first hidden layer and six neurons in the second hidden layer) and a tangent-sigmoid transfer function. This optimal network was implemented in MATLAB® to develop a model termed ISSP (Intelligent Simulator of Sprinkler Pattern). ISSP uses wind speed and direction as input variables and is able to simulate the distorted distribution pattern from a R3000 Rotator® sprinkler with reasonable accuracy (R2&gt; 0.935). Results of model evaluation confirm the accuracy and robustness of ANNs for simulation of a single sprinkler distribution pattern under real field conditions.

Orthogonal tests and precipitation estimates for the outside signal fluidic sprinkler

A new outside signal fluidic sprinkler is proposed in this paper. Its main structural parameters include offset length (A), working area length (B), plate cover diameter (C), and lead-flow length (D). An orthogonal array with four factors and three levels was selected to carry out the experiments. The factors influencing the coefficient of uniformity (CU) and range, in decreasing order of importance, were BADC and CDBA, respectively. The optimal values for the structural parameters were confirmed. The radial water distribution data for the sprinkler were obtained by experimentation. Water distribution figure for single sprinkler was drawn using Matrix Laboratory (MATLAB), which allowed for three-dimensional visualization of the data. The combined CU of the outside signal fluidic sprinkler was simulated for different combined spacing patterns. The CU was much larger in the rectangular configuration than in the triangular configuration. When the combined spacing coefficient was 1.2 to 1.3, the CU was found to exceed 75% in both the rectangular and triangular configurations.

EFFECT OF SPRINKLER RISER CHARACTERISTICS ON APPLICATION UNIFORMITY

The sprinkler riser characteristics; height, angle and rigid fixation are of great importance for the sprinkler application uniformity. Single sprinkler pattern tests were carried out to generate data required for field uniformities with different riser characteristics. Data from the single sprinkler tests were then overlapped to simulate system uniformities. Results were compared for different riser heights, riser angles, PVC and steel risers. Trials were carried out using two types of sprinkler heads. The statistical analysis indicated that riser characteristics affect significantly the application uniformity at 5 % significance level. However, the effect of some treatments was positive and for some others was negative. The negative effects of non-optimum riser characteristics can be minimized by closer spacing pattern.

Effects of water application intensity, drop size and water application amount on the characteristics of topsoil pores under sprinkler irrigation

Field experiments were carried out to study the effects of sprinkler irrigation on the characteristics of topsoil pores. Total soil porosity, capillary porosity, air-space porosity and porosities of different pore shapes were analyzed using images analysis of thin sections of soil samples. The experimental treatments included five water application intensities (5.3, 7.7, 11.0, 15.0 and 20.7 mm/h), five drop diameters (0.76, 1.28, 1.92, 3.18, 4.19 mm) and five water application amounts (9.0, 23.6, 37.5, 49.6, 59.4 mm). The compounding sprinkler system was used in the experiments of water application intensity and single sprinkler was used in the experiments of drop size and water application amount. The total porosity, air-space porosity and porosities of elongated pores have the similar decreasing tendency and pattern when water application intensity, drop diameter or water application amount increase. Capillary porosity, porosities of round and irregular pores have no obvious changing tendency. The decreasing porosities of the elongated pores and macropores are the main reasons for the decreasing of total porosity under sprinkler irrigation. To maintain soil structure in good conditions, the reasonable parameters would be considered for water application intensity, drop diameter and water application amount.