Evaluating water application uniformity of center pivot irrigation systems in typical regions of China

摘要

Center pivot irrigation systems have proven to be reliable, labor efficient and simple to operate. Since 1970s, center pivots have gradually increased to irrigate large farmlands, especially in northern and northeastern provinces in China. In order toinvestigate application status of the systems, six center pivots equipped with three kinds of low pressure sprinklers (Valley L.E.N., Nelson R3000, and Nelson D3000) in typical regions of China were chosen for performance evaluation. In this study, tests on water distribution of the center pivot systems were conducted under different percent timer settings. The catch cans were spaced 3 m apart uniformly along two straight lines perpendicular to the travel direction of the systems. The measured Heermannand Hein coefficient of uniformity ranged from 44.39% to 89.89%. This meant that some center pivot systems were in poor condition with low application uniformity, and the performances of these systems should be greatly improved. Factors affecting waterapplication uniformity included sprinkler type, operating pressure, end gun, wind speed, sprinkler mounting conditions, etc. The test results showed that improper pump selection led to high system inlet pressure and water depths overapplied by the end gun without a pressure control valve, compared with the values applied by the low pressure sprinklers of the system. Moreover, improper sprinkler configuration and installment also resulted in poor uniformity. Therefore, some suggestions were provided to improve water application uniformity of the center pivot systems.