USA · Irrigation Association · professional
General Ag exam (150 MCQs, 4 h) plus a specialty exam — Drip/Micro (75 questions, 4 h) or Sprinkler (50 questions, 4 h) — all within 3 years.
The clearest published content blueprint for irrigation design anywhere; useful to irrigation designers in any country.
Official source: https://www.irrigation.org/IA/FileUploads/IA/Certification/CertificationCandidateHandbook.pdf
Original questions written to this exam's published syllabus and pattern. Not past papers.
1. A 200 mm diameter pipe carries 50 L/s of water. What is the mean velocity?
D. 1.59 m/s
Q = 50 L/s = 0.05 m³/s; A = π(0.2)²/4 = 0.0314 m²; V = Q/A = 1.59 m/s. Using πD² without the 1/4 gives 0.398 m/s; converting 50 L/s to 0.5 m³/s gives 15.9 m/s. 1.25 m/s divides by D² and forgets π/4.
Fluid Mechanics & Open Channel Hydraulics · Continuity equation
2. A clay loam has volumetric field capacity 0.32 and wilting point 0.14. With a 1.2 m root zone and a management allowed depletion of 50 %, what is the readily available water?
D. 108 mm
TAW = 1000 × (0.32 − 0.14) × 1.2 = 216 mm. RAW = 0.5 × 216 = 108 mm. 216 mm is TAW, not RAW; 192 mm applies MAD to field capacity alone; 84 mm applies it to the wilting point water, which is unavailable.
Irrigation Engineering (Soil-Water-Plant, Conveyance, Surface Methods) · Soil-water-plant relations: field capacity, wilting point and MAD
3. On a centre pivot with sprinklers at equal spacing along the lateral, how must the discharge of each sprinkler vary with its distance r from the pivot to apply a uniform depth?
A. In proportion to r
Each sprinkler at radius r with spacing s serves an annulus of area about 2πr·s per revolution, so for equal depth its discharge must be proportional to r. Discharge proportional to r² would be the case only if the ring area grew with r², which it does not for a fixed spacing.
Sprinkler & Micro-Irrigation Systems · Sprinkler types and components
4. During a 48-hour pumping test the crew discharges the pumped water into a ditch 20 m from the well, over permeable sand. The likely effect on the results is:
B. Recirculation recharges the aquifer, flattening drawdown: T is overestimated or a false recharge boundary appears
Water returned near the test well infiltrates and partly supplies the pumping, flattening the late drawdown curve. Pumped water must be piped well away from the cone of depression.
Groundwater, Wells & Pumps · Pumping tests
5. A 2,000 m² greenhouse has a crop water use of 5 mm/d and a drip application efficiency of 90%. There are 6,000 plants, each on one 1.6 L/h dripper. How long must the system run each day?
B. 69 min
Volume = 2,000 × 0.005 / 0.9 = 11.11 m³/d. Flow = 6,000 × 1.6 = 9,600 L/h = 9.6 m³/h. Time = 11.11 / 9.6 = 1.157 h = 69 min. 63 min ignores efficiency; 1.2 min is hours mislabelled as minutes; 694 min is a factor-of-ten slip.
Protected Cultivation & Greenhouse Engineering · Micro-irrigation and fertigation in greenhouses
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