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IRRIGATION EFFICIENCY MODIFICATIONS

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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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