CLA CLA Irrigation & Water Management 2 — Questions and Answers
Question 1: What is 'distribution uniformity' (DU) in irrigation system design?
- The percentage of heads in a zone that turn on
- A measure of how evenly water is applied across the irrigated area (Correct answer)
- The total pipe length per irrigation zone
- The flow rate divided by the emitter count
Correct answer: A measure of how evenly water is applied across the irrigated area
Distribution uniformity (DU) measures how consistently water is applied; a DU of 100% means every point receives exactly the same amount.
Question 2: Which irrigation design principle ensures that all sprinkler heads in a zone have the same precipitation rate to achieve uniform coverage?
- Head-to-head spacing
- Matched precipitation rate (MPR) (Correct answer)
- Pressure regulation
- Hydrozone grouping
Correct answer: Matched precipitation rate (MPR)
Matched precipitation rate design means rotors and fixed sprays in the same zone apply water at the same rate, preventing dry or soggy spots.
Question 3: What is a 'hydrozone' in landscape irrigation planning?
- A wetland buffer zone around a pond
- A grouping of plants with similar water requirements served by a dedicated irrigation zone (Correct answer)
- The area covered by one sprinkler head
- A pressurized irrigation pipe section
Correct answer: A grouping of plants with similar water requirements served by a dedicated irrigation zone
Hydrozoning groups plants with similar water needs on the same irrigation zone to avoid overwatering drought-tolerant plants or underwatering thirsty ones.
Question 4: What does the acronym 'WUCOLS' stand for, and how is it used?
- Water Use Classification of Landscape Species — a California reference guide for plant water needs (Correct answer)
- Watershed Uniform Code of Landscape Standards
- Weekly Usage Control of Landscaped Sites
- Water Use Calculations for Outdoor Landscapes and Structures
Correct answer: Water Use Classification of Landscape Species — a California reference guide for plant water needs
WUCOLS (Water Use Classification of Landscape Species) is a California DWR publication that categorizes landscape plants as high, moderate, low, or very low water users.
Question 5: What is the function of a 'master valve' in an irrigation system?
- Regulates pressure for all zones
- Acts as a main shutoff that opens only when an irrigation zone is active, preventing leaks when system is off (Correct answer)
- Controls the backflow preventer
- Divides flow between two separate irrigation systems
Correct answer: Acts as a main shutoff that opens only when an irrigation zone is active, preventing leaks when system is off
A master valve at the main line closes when no zone is running, protecting against leaks from a broken lateral or stuck valve anywhere in the system.
Question 6: When designing irrigation for a slope, which practice helps prevent runoff and promotes infiltration?
- Use higher precipitation rate heads
- Use cycle-and-soak scheduling with multiple short run times (Correct answer)
- Group slope zones with flat areas for efficiency
- Use impact sprinklers for better throw
Correct answer: Use cycle-and-soak scheduling with multiple short run times
Cycle-and-soak applies water in multiple short cycles with rest periods, allowing the soil to absorb each application before more is added.
CLA CLA Irrigation & Water Management 2
What is 'distribution uniformity' (DU) in irrigation system design?