Distribution uniformity

From Wikipedia, the free encyclopedia

Distribution Uniformity or DU in irrigation is a measure of how uniformly water is applied to the area being watered, expressed as a percentage. The most common measure of DU is the Low Quarter DU, which is a measure of the average of the lowest quarter of samples, divided by the average of all samples. The higher the DU, the better the performance of the system. If all samples are equal, the DU is 100%. DU is calculated when performing an irrigation audit.

Distribution uniformity is useful when determining the total watering requirement during irrigation scheduling. For example, an irrigator might want to apply not less than one inch of water to the area being watered. If the DU were 75%, then the total amount to be applied would be the desired amount of water, divided by the DU. In this case, the required irrigation would be 1.33 inches of water, so that only a very small area received less than one inch. The lower the DU, the less efficient the distribution, and thus the more water that must be applied to meet the minimum requirement.