CLA CLA Irrigation & Water Management 1 — Questions and Answers
Question 1: What does 'ET' stand for in irrigation scheduling, and why is it important?
- Estimated total runoff
- Evapotranspiration — the combined water loss from soil evaporation and plant transpiration (Correct answer)
- Elevation threshold for pressure zones
- Emitter type for drip systems
Correct answer: Evapotranspiration — the combined water loss from soil evaporation and plant transpiration
Evapotranspiration (ET) measures total water loss from the landscape and is the primary basis for calculating how much supplemental irrigation is needed.
Question 2: Which irrigation head type delivers water directly to the root zone and is most efficient for water conservation?
- Rotary pop-up head
- Fixed spray head
- Drip emitter (Correct answer)
- Impact sprinkler
Correct answer: Drip emitter
Drip emitters deliver water slowly at the root zone, minimizing evaporation and overspray losses and achieving application efficiencies of 90%+.
Question 3: What is the purpose of a backflow preventer in a landscape irrigation system?
- Regulate water pressure to sprinkler heads
- Prevent irrigation water from flowing back into the potable water supply (Correct answer)
- Reduce pipe pressure surges
- Filter particulates from the water supply
Correct answer: Prevent irrigation water from flowing back into the potable water supply
A backflow preventer is a plumbing device required by code to protect the drinking water supply from contamination by irrigation system water.
Question 4: What does 'precipitation rate' mean for a sprinkler system, and in what unit is it expressed?
- Total gallons used per irrigation cycle
- The rate at which water is applied to the landscape, expressed in inches per hour (Correct answer)
- The number of sprinkler heads per zone
- Water pressure at the head, expressed in PSI
Correct answer: The rate at which water is applied to the landscape, expressed in inches per hour
Precipitation rate describes how quickly water accumulates on the soil surface, measured in inches per hour — it must match or be less than the soil infiltration rate to avoid runoff.
Question 5: A 'smart' irrigation controller adjusts watering schedules based on:
- Preset timer only
- Weather data or soil moisture sensors to match actual plant water needs (Correct answer)
- Manual input from the homeowner each day
- The number of zones in the system
Correct answer: Weather data or soil moisture sensors to match actual plant water needs
Smart controllers use real-time ET data, weather forecasts, or in-ground soil sensors to automatically adjust run times, reducing water waste.
Question 6: What is the minimum recommended operating pressure for most standard pop-up rotary sprinkler heads?
- 10–15 PSI
- 25–30 PSI (Correct answer)
- 45–55 PSI
- 70–80 PSI
Correct answer: 25–30 PSI
Most rotary sprinkler heads require 25–45 PSI to operate correctly; below 25 PSI, distribution uniformity degrades significantly.
CLA CLA Irrigation & Water Management 1
What does 'ET' stand for in irrigation scheduling, and why is it important?