Water Auditing & Irrigation Efficiency Flashcards

The Irrigation Association defines a landscape irrigation audit as a process to evaluate:

Answer: How efficiently and uniformly an irrigation system applies water

An IA landscape irrigation audit evaluates system performance including uniformity, application rates, scheduling, and overall water use efficiency.

Distribution Uniformity Low Quarter (DU_lq) is calculated by dividing the average of the lowest 25% of catch can readings by:

Answer: The overall average of all catch can readings

DU_lq = (average of lowest 25% catch readings) / (average of all catch readings) × 100%, indicating how uniformly water is distributed.

What is the minimum acceptable DU_lq percentage recommended by the Irrigation Association for landscape systems?

Answer: 70%

The IA recommends a minimum DU_lq of 70% for landscape sprinkler systems; values below this indicate significant waste or dry spots.

During a catch can audit, how many cans are typically placed in a single irrigation zone?

Answer: At least 8–16 cans per zone in a grid pattern

IA protocols recommend placing a minimum of 8–16 catch cans in a grid pattern across the zone to capture variability and calculate meaningful DU.

An irrigation audit station flow rate is determined by measuring:

Answer: The volume of water discharged from a zone over a measured time period

Station flow rate (GPM) is measured by recording the volume flowing through a meter or bucket test over a timed period while the zone runs.

Schedule efficiency (SE) in irrigation describes:

Answer: How well the irrigation schedule matches actual plant water demand

Schedule efficiency measures how closely the programmed irrigation matches the ET-based water requirement; over-scheduling wastes water and reduces SE.