LARE LARE Irrigation Design 2 — Questions and Answers
Question 1: What does 'matched precipitation rate' (MPR) technology accomplish in an irrigation zone?
- It matches the irrigation rate to the site's annual rainfall amount
- It ensures that quarter-, half-, and full-circle heads in the same zone all apply water at the same rate (Correct answer)
- It calculates precipitation rate relative to soil texture
- It sets the controller runtime to match forecasted weather
Correct answer: It ensures that quarter-, half-, and full-circle heads in the same zone all apply water at the same rate
MPR technology ensures heads with different arc sizes apply water at the same depth per hour so the entire zone receives uniform coverage without wet or dry spots.
Question 2: What is the function of a pressure-compensating emitter in a drip irrigation system?
- It prevents backflow into the potable supply
- It maintains a consistent flow rate across a wide range of operating pressures (Correct answer)
- It filters particles from the water before distribution
- It automatically flushes debris from the end of the lateral
Correct answer: It maintains a consistent flow rate across a wide range of operating pressures
Pressure-compensating emitters maintain a consistent output flow rate despite variations in operating pressure, ensuring uniform application on slopes or long lateral runs.
Question 3: What term describes the combined water loss from soil evaporation and plant transpiration?
- Percolation
- Runoff coefficient
- Evapotranspiration (ET) (Correct answer)
- Infiltration rate
Correct answer: Evapotranspiration (ET)
Evapotranspiration (ET) combines evaporation from soil and transpiration through plant tissue, representing the total water demand that irrigation must replace.
Question 4: What is the purpose of a check valve built into rotor and spray heads?
- To prevent low-head drainage after the zone valve closes on sloped sites (Correct answer)
- To increase static pressure at the head
- To filter debris before it reaches the nozzle
- To limit the arc of rotation to a preset angle
Correct answer: To prevent low-head drainage after the zone valve closes on sloped sites
Check valves in heads prevent low-head drainage, where water drains out of the lowest heads in a zone after the valve closes, wasting water and causing puddles or erosion.
Question 5: Which irrigation method is generally the most water-efficient for trees and shrubs in a landscape?
- Overhead spray system
- Subsurface drip irrigation (Correct answer)
- Gear-driven rotor system
- Above-ground bubbler system
Correct answer: Subsurface drip irrigation
Subsurface drip irrigation delivers water directly to the root zone with minimal evaporation or runoff losses, making it the most efficient delivery method for woody plants.
Question 6: What does 'distribution uniformity' (DU) measure in an irrigation system?
- The equal spacing of heads across a zone layout
- How evenly water is applied across all parts of an irrigated area (Correct answer)
- The uniformity of operating pressure throughout the system
- The consistency of pipe diameters used in the design
Correct answer: How evenly water is applied across all parts of an irrigated area
Distribution uniformity quantifies how evenly water is distributed across an irrigated area; a higher DU means more consistent coverage and less over- or under-watering of any given spot.
Question 7: In irrigation design, what is 'hydrozoning'?
- Grouping plants with similar water requirements into the same irrigation zone (Correct answer)
- Creating separate water meters for each irrigation zone
- Designing dedicated irrigation circuits for water features only
- Installing pressure regulation at different site elevations
Correct answer: Grouping plants with similar water requirements into the same irrigation zone
Hydrozoning groups plants with similar water needs—high, moderate, or low/drought-tolerant—into a single irrigation zone so water can be applied at the rate appropriate for that plant community.
LARE LARE Irrigation Design 2
What does 'matched precipitation rate' (MPR) technology accomplish in an irrigation zone?