During the tests, the computer measures water application rates at various distances from the sprinkler. It then overlaps the spray patterns of individual sprinklers at the chosen spacing to simulate the irrigation pattern. The higher the CU, the more uniform the water application. The ideal CU is 100 percent, but that is unattainable - even rainfall isn't 100 percent uniform. Turfgrass irrigators generally are more interested in combating dry spots than wet spots.
Most people readily understand the denso-gram's display of irrigation patterns.
In contrast, only those who are very familiar with irrigation uniformity analysis have a good comprehension of the significance of CU numbers. Both denso-grams shown here are based on the same sprinkler head, but the sprinkler spacing differs. The denso-gram above clearly indicates too much space between sprinklers, which can lead to poor coverage. The denso-gram below shows the coverage when the spacing problem is solved. The denso-gram visually displays the irrigation wetting pattern between the sprinklers.