IA Water Auditing & Irrigation Efficiency 1 — Questions and Answers
Question 1: The Irrigation Association defines a landscape irrigation audit as a process to evaluate:
- Soil nutrient levels
- How efficiently and uniformly an irrigation system applies water (Correct answer)
- The financial cost of the irrigation system
- The legal compliance of backflow preventers
Correct 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.
Question 2: Distribution Uniformity Low Quarter (DU_lq) is calculated by dividing the average of the lowest 25% of catch can readings by:
- The highest single reading
- The overall average of all catch can readings (Correct answer)
- The median reading
- The design precipitation rate
Correct 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.
Question 3: What is the minimum acceptable DU_lq percentage recommended by the Irrigation Association for landscape systems?
- 40%
- 55%
- 70% (Correct answer)
- 90%
Correct answer: 70%
The IA recommends a minimum DU_lq of 70% for landscape sprinkler systems; values below this indicate significant waste or dry spots.
Question 4: During a catch can audit, how many cans are typically placed in a single irrigation zone?
- 1–2 cans per zone
- 3–4 cans per zone
- At least 8–16 cans per zone in a grid pattern (Correct answer)
- One can per sprinkler head
Correct 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.
Question 5: An irrigation audit station flow rate is determined by measuring:
- Static pressure only
- The volume of water discharged from a zone over a measured time period (Correct answer)
- The number of heads in the zone
- The pipe diameter at the valve
Correct 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.
Question 6: Schedule efficiency (SE) in irrigation describes:
- The ratio of gallons applied to gallons metered
- How well the irrigation schedule matches actual plant water demand (Correct answer)
- The pump motor efficiency rating
- The number of zones completed per hour
Correct 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.
IA Water Auditing & Irrigation Efficiency 1
The Irrigation Association defines a landscape irrigation audit as a process to evaluate: