Dripline flushing is a maintenance procedure that is recommended for all microirrigation systems. However, flushing velocity and flushing duration, which particularly affect the design and management of subsurface drip irrigation (SDI) systems, have not been studied extensively. For a better understanding of the flushing process in driplines and manifolds, a laboratory study was conducted at Kansas State University with a 10 m transparent pipe simulating an SDI dripline. Three different sediments with sizes up to 500 µm were introduced into the pipeline, and their distribution along the pipeline was analyzed under different flushing velocities over various times. Head loss under the conditions of this study increased exponentially with increased flushing velocity, suggesting that the flow regimes could be characterized between moving beds and heterogeneous flow. The percentage of pipeline blockage was logarithmically related to the flushing velocity, with greater than 30% of the pipeline occupied by larger sand sediments when the flushing velocity was less than 0.3 m sˉ¹. Although flushing velocities at or near the calculated deposition velocity could remove the majority of the sediments with a short duration of 15 min or less, flushing velocities that were approximately 45% to 65% of the deposition velocity could achieve similar sediment removal with longer flushing duration (up to 180 min). The ASAE EP-405 recommended minimum flushing velocity of 0.3 m sˉ¹ still appears adequate for most microirrigation systems operating under typical conditions. Designers are encouraged to calculate the deposition velocity for new microirrigation systems and to use it as a flexible guideline to assess the adequacy of flushing. End-users are encouraged to extend the duration of flushing for perhaps as long as 5 min after the initial concentration of sediments are removed to improve overall flushing. Further research is warranted to evaluate flushing velocity, but the results of this study should be representatively instructive of the phenomenon of sediment transport in microirrigation driplines during flushing.
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机译：滴水冲洗是所有微灌溉系统推荐的维护程序。然而，尚未特别研究冲洗速度和冲洗持续时间，冲洗速度和冲洗持续时间特别影响地下滴灌（SDI）系统的设计和管理。为了更好地了解滴水管和集水管中的冲洗过程，堪萨斯州立大学进行了一项实验室研究，使用一根10 m透明的管道模拟SDI滴水管。将三种尺寸最大为500 µm的不同沉积物引入管道，并在不同的冲洗速度下，分析了它们沿管道的分布。在本研究条件下，水头损失随冲洗速度的增加呈指数增长，这表明流动床和非均质流动之间的流态可以被表征。管道堵塞的百分比与冲洗速度成对数关系，当冲洗速度低于0.3 m s -1时，较大的沙子沉积物会占据管道的30％以上。尽管在等于或接近计算的沉积速度下的冲洗速度可以在15分钟或更短的时间内将大部分沉积物清除，但冲洗速度大约为沉积速度的45％至65％可以在较长的冲洗时间下实现类似的沉积物清除（最多180分钟）。 ASAE EP-405建议的最低冲洗速度为0.3 m s -1，对于大多数在典型条件下运行的微灌溉系统而言似乎仍然足够。鼓励设计人员计算新的微灌溉系统的沉积速度，并将其用作评估冲洗是否足够的灵活指南。鼓励最终用户在去除沉积物的初始浓度后将冲洗时间延长可能长达5分钟，以改善整体冲洗效果。有必要进行进一步的研究来评估冲洗速度，但这项研究的结果应具有代表性，可指导冲洗过程中微灌溉滴水线中的泥沙输送现象。
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