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IRRIGATION EFFICIENCY MODIFICATIONS

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. System Types. LEPA - Bubbler mode 8”-18” above soil, or drag socks.

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IRRIGATION EFFICIENCY MODIFICATIONS

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  1. IRRIGATION EFFICIENCY MODIFICATIONS MERLIN N. NELSON NRCS

  2. Introduction • Basic system efficiencies • Effects on Sprinklers by Pressure, Terrain, and Wind • Planning considerations • Documentation tools and resources

  3. System Types

  4. LEPA - Bubbler mode 8”-18” above soil, or drag socks

  5. 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

  6. Elevation changes in the field

  7. 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)

  8. Pressure effects pattern breakup

  9. Typical Application Rates

  10. Sprinkler pressure measurement

  11. Topic Two --- Wind • Evaluations

  12. 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

  13. 3 Dimensional Patterns

  14. Pattern graphic

  15. 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%

  16. 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

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