Effect of Catch-Can Spacing on Calculation of Sprinkler Irrigation Application Uniformity

摘要

Sprinkler irrigation application uniformity is an important indicator for sprinkler irrigation system design, which can be expressed by the Christiansen uniformity coefficient (CU). The calculated accuracy of CU is closely related with catch-can spacing and grid size. In theory, the smaller the catch-can spacing and grid size are, the more accurate the calculation of CU is. However, smaller catch-can spacing needs more labor in water distribution measurement, and smaller grid size needs more computer runtime to calculate CU. In order to recommend the proper catch-can spacing and grid size, an experiment is carried out to obtain four different water distribution patterns, and data characteristics for water distribution with various catch-can spacing and the effect of catch-can spacing and grid size on CU are studied in the paper. The results show that CU is overestimated for the larger catch-can spacing, especially when the distribution of water for the pattern is non-uniformity. CU changes very little within a certain catch-can spacing and grid size for all the four patterns. Considering the accuracy of CU calculation, labor cost, and the computational runtime, the recommended catch-can spacing is 1.96m for pattern I, 0.92m for patterns III and IV, and the recommended grid size in the calculation of CU is 1.25, 1.0, and 0.5m for patterns I, III, and IV, respectively.