IA Cheat Sheet 2026
The 30 highest-yield IA facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.
- What is the formula for calculating the precipitation rate (PR) of a sprinkler system? → PR = [96.3 × Flow (GPM)] / Area (sq ft)
- Pump efficiency (Ep) is defined as the ratio of: → Water horsepower (WHP) to brake horsepower (BHP)
- What is the primary purpose of a zone in an irrigation system? → To group areas with similar watering needs
- On a centrifugal pump curve, what is the 'best efficiency point' (BEP)? → The point on the pump curve where the pump operates at its highest efficiency
- During a catch can audit, how many cans are typically placed in a single irrigation zone? → At least 8–16 cans per zone in a grid pattern
- What is the primary role of evapotranspiration (ET) in irrigation? → To estimate water needs
- In hot, arid climates, how does the crop coefficient (Kc) of turfgrass typically compare to humid climates? → It may be higher due to greater atmospheric demand and more advective energy
- Brake horsepower (BHP) of a pump is calculated using which formula? → BHP = Flow (GPM) × TDH / 3,960 × pump efficiency
- In a water budget approach to irrigation management, the maximum allowed water use (MAW) is based on: → A calculated ET-based water allowance for the landscape area
- What is field capacity in relation to soil moisture? → Water held in soil after free drainage
- Landscape water use efficiency (WUE) is expressed as the ratio of: → Water beneficially used to total water applied
- What is the minimum acceptable DU_lq percentage recommended by the Irrigation Association for landscape systems? → 70%
- Which instrument is used to directly measure reference evapotranspiration in the field? → Lysimeter
- Which controller program type allows different zones to run on different days of the week? → Day-of-week program
- Which backflow prevention assembly provides the highest level of protection against both back-pressure and back-siphonage? → Reduced Pressure Zone (RPZ) assembly
- An irrigation audit station flow rate is determined by measuring: → The volume of water discharged from a zone over a measured time period
- What is 'head-to-head spacing' in sprinkler design? → Spacing where one head's throw distance equals the spacing between heads
- What term describes the variation in application rates across multiple sprinkler heads in a zone due to hydraulic differences? → Coefficient of variation (CV)
- What is the significance of the pump curve intersection with the system curve? → It is the operating point where the pump actually runs in the system
- Wire-to-water efficiency of a pump system measures overall efficiency from: → Electrical power input at the utility meter to hydraulic power delivered to the water
- Low-volume irrigation systems, including drip and micro-spray, generally achieve higher application efficiency because they: → Apply water slowly near the root zone, minimizing evaporation and overspray
- The term 'runoff' in landscape irrigation refers to water that: → Exceeds the soil's infiltration rate and flows off the landscape surface
- What is the main benefit of drip irrigation systems? → Delivers water efficiently to root zone
- What instrument does a certified backflow tester use to field-test assemblies? → A differential pressure gauge test kit with hoses connected to the assembly's test cocks
- What is 'effective rainfall' in an irrigation context? → The portion of rainfall that is stored in the root zone and available for plant use
- What type of sensor can be wired to a controller's sensor input to automatically suspend irrigation when the soil has sufficient moisture? → Soil moisture sensor (tensiometer or capacitance probe)
- How does slope affect irrigation efficiency? → Causes runoff and uneven watering
- Distribution Uniformity Low Quarter (DU_lq) is calculated by dividing the average of the lowest 25% of catch can readings by: → The overall average of all catch can readings
- Which organization is the primary authority for backflow prevention standards and tester certification in the United States? → USC Foundation for Cross-Connection Control and Hydraulic Research (USC-FCCC)
- What does a controller's 'common wire' do? → Completes the valve circuit
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