IRRIGATION EFFICIENCY MODIFICATIONS
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Learn about improving irrigation efficiency through system modifications such as LEPA and pressure management. Understand how wind impacts sprinkler performance and access resources for further information.
IRRIGATION EFFICIENCY MODIFICATIONS
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Presentation Transcript
IRRIGATION EFFICIENCY MODIFICATIONS MERLIN N. NELSON NRCS
Introduction • Basic system efficiencies • Effects on Sprinklers by Pressure, Terrain, and Wind • Planning considerations • Documentation tools and resources
Efficiency Overview • NATIONAL IRRIGATION GUIDE • (Table 6-4) • Periodic move lateral 60-75% • Traveling sprinkler (big guns) 55-65% • Center pivot - standard 75-85% • Linear (lateral) move 80-87% • LEPA Center pivot or linear 90-95
Topic One --- Pressure At Sprinkler Heads • Elevation changes within a field • 2.3 feet of elev. change = 1 psi • System operation pressures • STD. 442 allows a max. 20% pressure change for sprinklers in a lateral. (i.e. 23 feet or 10 psi friction loss max. for a 50 psi system)
Topic Two --- Wind • Evaluations
NEH Section 15, Chapter 11 Table 11 - 9,10,11,12 • 40ft. x 60 ft. spacing --- 50 psi pressure • 0.25 iph 0.30 iph 0.35 iph • 11/64 nozzle 3/16 nozzle 13/64 nozzle • Wind uniformity coefficient (CU) • 0-4 85 85 84 • 4-10 81 83 84 • 10-15 74 78 81 • 15-20 70 73 74
Summary • Table 11-7 shows CU effects on 1.0 inch gross application. • Example: A CU of 74 % requires 1.0 inch divided by 0.66 or 1.52 inch gross to irrigate 85% of the area adequately. • A 75% efficient sprinkler that applies a gross of 4 in. to get a net of 3 in., would need to apply a gross of 6.04 in. for a 3 in. net w/ 20 mph winds. Efficiency = 49.7%
Where to get more information • Other training sessions - IWM II, III • National and Montana Irrigation Guides • National Engineering Handbook, Section 15, Chapter 11 • ASAE, other sources • Request feedback of training session