What does distribution uniformity (DU) measure in a catch-can test?

What does distribution uniformity (DU) measure in a catch-can test?

• A. The pressure in the irrigation mainline.
• B. The total water applied to the zone.
• C. The uniformity of water distribution across the zone, comparing the lowest quarter to the average.
• D. The rate of evaporation from the soil.

Answer: (C)

Distribution uniformity is about how evenly water is applied across the irrigation zone. In a catch-can test, you measure how much water each can collects and then look at the average depth in the lowest 25% of cans and compare it to the overall average depth. The ratio of the lowest-quarter average to the overall average (expressed as a percentage) shows how uniform the distribution is: higher values mean more even coverage, lower values indicate uneven application. This concept is separate from pressure, total water applied, or evaporation, which are different aspects of irrigation performance.

Distribution uniformity is about how evenly water is applied across the irrigation zone. In a catch-can test, you measure how much water each can collects and then look at the average depth in the lowest 25% of cans and compare it to the overall average depth. The ratio of the lowest-quarter average to the overall average (expressed as a percentage) shows how uniform the distribution is: higher values mean more even coverage, lower values indicate uneven application. This concept is separate from pressure, total water applied, or evaporation, which are different aspects of irrigation performance.