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IRRIGATION EFFICIENCY IRRIGATION EFFICIENCY MODIFICATIONSMODIFICATIONS

MERLIN N. NELSONMERLIN N. NELSON

NRCS

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Introduction Introduction

Basic system efficienciesBasic system efficiencies Effects on Sprinklers by Pressure, Effects on Sprinklers by Pressure,

Terrain, and WindTerrain, and Wind Planning considerationsPlanning considerations Documentation tools and resourcesDocumentation tools and resources

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System TypesSystem Types

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

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Efficiency Overview Efficiency Overview

NATIONAL IRRIGATION GUIDENATIONAL IRRIGATION GUIDE (Table 6-4)(Table 6-4)

– Periodic move lateral 60-75%Periodic move lateral 60-75%– Traveling sprinkler (big guns) 55-65%Traveling sprinkler (big guns) 55-65%– Center pivot - standard 75-85%Center pivot - standard 75-85%– Linear (lateral) move 80-87%Linear (lateral) move 80-87%– LEPA Center pivot or linear 90-95LEPA Center pivot or linear 90-95

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Elevation changes in the fieldElevation changes in the field

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Topic One --- Pressure Topic One --- Pressure At Sprinkler HeadsAt Sprinkler Heads

Elevation changes within a field Elevation changes within a field – 2.3 feet of elev. change = 1 psi2.3 feet of elev. change = 1 psi

System operation pressuresSystem operation pressures– STD. 442 allows a max. 20% pressure change STD. 442 allows a max. 20% pressure change

for sprinklers in a lateral. (i.e. 23 feet or 10 psi for sprinklers in a lateral. (i.e. 23 feet or 10 psi friction loss max. for a 50 psi system)friction loss max. for a 50 psi system)

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Pressure effects pattern breakup Pressure effects pattern breakup

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Typical Application Rates Typical Application Rates

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Sprinkler pressure measurement Sprinkler pressure measurement

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Topic Two --- WindTopic Two --- Wind

EvaluationsEvaluations

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NEH Section 15, Chapter 11 NEH Section 15, Chapter 11 Table 11 - 9,10,11,12Table 11 - 9,10,11,12

40ft. x 60 ft. spacing --- 50 psi pressure40ft. x 60 ft. spacing --- 50 psi pressure 0.25 iph 0.30 iph 0.35 iph0.25 iph 0.30 iph 0.35 iph 11/64 nozzle 3/16 nozzle 13/64 nozzle11/64 nozzle 3/16 nozzle 13/64 nozzle

Wind uniformity coefficient (CU)Wind uniformity coefficient (CU) 0-4 85 85 840-4 85 85 84 4-10 81 83 844-10 81 83 84 10-15 74 78 8110-15 74 78 81 15-20 70 73 7415-20 70 73 74

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Pattern graphicPattern graphic

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SummarySummary

Table 11-7 shows CU effects on 1.0 inch gross Table 11-7 shows CU effects on 1.0 inch gross application.application.

Example: A CU of 74 % requires 1.0 inch Example: A CU of 74 % requires 1.0 inch divided by 0.66 or 1.52 inch gross to irrigate divided by 0.66 or 1.52 inch gross to irrigate 85% of the area adequately.85% of the area adequately.

A 75% efficient sprinkler that applies a gross of A 75% efficient sprinkler that applies a gross of 4 in. to get a net of 3 in., would need to apply a 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. gross of 6.04 in. for a 3 in. net w/ 20 mph winds. Efficiency = 49.7%Efficiency = 49.7%

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Where to get more informationWhere to get more information

Other training sessions - IWM II, IIIOther training sessions - IWM II, III National and Montana Irrigation GuidesNational and Montana Irrigation Guides National Engineering Handbook, Section National Engineering Handbook, Section

15, Chapter 1115, Chapter 11 ASAE, other sources ASAE, other sources Request feedback of training sessionRequest feedback of training session