The aim of the study was to improve the method for assessment of irrigation uniformity according to the results of apparatus testing by radial method. During the study it is established that algorithm for calculating the indices of uniformity according to GOST ISO 7749-2–2004 is useful only at an installation step which is greater than irrigation radius of apparatus. However, many apparatus show the higher uniformity at a less installation step. In this connection, during the study the algorithm for calculating indices of rain uniformity recommended by GOST ISO 7749-2–2004 was improved in order to increase the accuracy of calculation at different conditions of apparatus location and to determine an optimal step of their installation. To minimize manual operations of calculation and measurement the improved algorithm was realized in computer software. The test-data processing of the apparatus i-Wob of Senninger Company has shown that the assessment of rain uniformity according to the improved algorithm and coefficient of efficient irrigation event gives similar results. An optimal step for installation of the apparatus i-Wob is equal to 9.5 m, what is close to an irrigation radius. The study results of double-nozzle unit of center-pivot “Fregat” without screw sprinkler attachment according to the assessment by the standard doesn’t satisfy the requirements for irrigation uniformity but while an installation step decreasing this parameter is improved. The assessment of uniformity of the apparatus according to the standard at an installation step B < 16 m isn’t reliable since the water from adjacent devices is not taken into account. In this case the use of proposed algorithm enables to increase the accuracy of rain uniformity indices.
Keywords: sprinkling, sprinkler apparatus, sprinkling machine, rain uniformity, Christiansen uniformity coefficient, coefficient of effective irrigation, coefficient of insufficient watering, coefficient of excess watering.
