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Transcript of 0 Study of Irrigation Scheduling Practices in the Pacific Northwest Sponsored by: Bonneville Power...
1
Study of Irrigation Scheduling Practices
in the Pacific Northwest
Sponsored by:Bonneville Power Administration,
Pacific Northwest Generating Co-Op., and
Northwest Energy Efficiency Alliance
April 5, 2005
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Project Scope & Objectives
Phase I: Survey irrigation water management and scheduling practices in the
region
Define scientific irrigation scheduling (SIS) and develop a baseline for its practice
Collect and analyze data on irrigation water use
Develop a plan for Phase II
Phase II: Measure water savings from the SIS
Develop a simplified methodology for calculating energy savings
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Project TeamProject Team
Project Funding: Bonneville Power Administration Pacific Northwest Generating Authority Northwest Energy Efficiency Alliance
Utility Sponsors: Franklin County PUD, Benton PUD # 1, Umatilla Electric Co-Op., Grant
County PUD
Technical Team: Bonneville Oregon State University Department of Bioengineering IRZ Consulting Ground Water Management Association Franklin County Conservation District
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Scope of the StudyScope of the Study
Phase I Phase II
Farm & Crop Characteristics
Irrigation Scheduling Methods
Farm Management Practices
BaselinePractices
Actual Water Use
Energy Consumption
Deemed Savings Methodology
Implications for C&RD
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Phase I Study DesignPhase I Study Design
Working Hypotheses:
1. “All growers use a certain irrigation regime.” 2. “What distinguishes these regimes is the basis on which irrigation decisions
are made and the intensity with which this information is applied.”
Corollary Assumptions:
1. “A good irrigation practice means knowing how much water to apply and when to do it.”
2. ” A well-managed irrigation regime can save water and, hence, pumping energy use.”
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Phase I Scope & Methods
Study Period: Data Collection: January – March 2003
Final Report: December 2003
Sample Size: Surveyed 776 growers in three states (ID, OR, WA); 11 irrigation sub-
regions; 13 PUDs (75%); 3 IOUs (25%)
Data Elements: Basic Farm Characteristics
Irrigation System
Irrigation Water Management Practices
Demographics
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Scientific Irrigation Scientific Irrigation Scheduling: DefinitionScheduling: Definition
Scientific irrigation scheduling generally refers to the practice of meeting crop moisture requirements by supplying the right amount of water at the right time based on measurement of actual soil moisture and evapotranspiration (ET).
Criteria for SIS:
1. Knowledge of crop ET2. Appropriate measurement of soil moisture of crop water status3. Measurement and monitoring of actual amounts of applied
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Scientific Irrigation Scientific Irrigation Scheduling: CriteriaScheduling: Criteria
Practice Level
Use Scheduling Services
Measure Soil Moisture or Plant Water
StatusUse ET
Measure Applied Water
I Yes
Yes Yes Yes
II
Yes Yes
Yes Yes
III
Yes
Yes
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Summary of Phase I Summary of Phase I FindingsFindings
General Characteristics: Alfalfa is the prominent crop (31% of irrigated acres), followed by wheat
(17%), vegetables (10%), corn (15%), and potatoes (7%).
94% of farms use pressurized pump systems.
Local utilities are the main source of power; 4% report using on-site generation.
On-line services, primarily AgriMet, are the most commonly used sources for ET and account for 45 percent of cases.
Sprinklers are the common irrigation system (82%); gravity systems (15%); micro-irrigation, sub-surface irrigation (3%).
Irrigation districts (44%), groundwater (29%), surface water (24%) are the main sources of irrigation water recaptured tail water, wastewater, and other sources account for the remaining 5%.
Irrigation Scheduling Practices: Nearly 80 percent of farms do not use irrigation water management and only
11% use irrigation practices that meet this study’s definition of SIS.
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Summary of Phase I Summary of Phase I ResultsResults
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Summary of Phase I Summary of Phase I FindingsFindings
Scheduling Practices: Nearly 80 percent of farms do not use irrigation water management and only
11% use irrigation practices that meet this study’s definition of SIS.
Practice Level Farms Percent Irrigated Acres Percent
I 90 12% 155,175 32%
II 75 10% 52,339 11%
III 611 79% 274,270 57%
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Phase II Scope & MethodsStudy Period: Data Collection: 2004 Irrigation Season (March – October 2003)
Final Report: March 2005
Sample Size: 44 fields (22 treatment and 22 control) farms in the Benton, Franklin, Morrow and
Umatilla counties
5 fields were dropped due to equipment failure/malfunction
Data Elements: General farm and field characteristics
Irrigation system specifications
15-minute pump system status readings (using pressure gages and data loggers)
Soil water content (regular neutron probe readings)
Flow measurements (ultrasonic flow readings)
Evapotranspiration (AgriMet)
Precipitation (NOAA)
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Phase II Study DesignPhase II Study Design
Study GroupW
ater
App
licat
ion
Idea
lA
ctua
lControlTreatment
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Calculation of Water Calculation of Water SavingsSavings
Water savings from SIS are derived by comparing the difference between Actual Water Use (AW), based on field measurements, and irrigation requirements, Ideal Water Use (IW), across the two groups, that is:
Water Savings = (AWTreatment – IWTreatment) - (AWControl – IWControl)
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Calculation of Ideal Water Calculation of Ideal Water RequirementsRequirements
0 applS
SEffS
C EIRGrossSMRET
Where:
• ΣGross IRS is the gross seasonal water requirement
• ΣETc is the cumulative seasonal crop consumptive use of water
• REff is the effective rainfall during that period
• ΔSMS is the change in soil water storage during the season (the storage at end of season less the antecedent moisture)
• Eappl is the application efficiency, the proportion of water delivered to the field that is effectively stored in the root zone for use by the crop
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The Water Balance The Water Balance ModelModel
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Calculation of Energy Calculation of Energy SavingsSavings
Where:
• TDH = total dynamic head (pumping lift, pressure and head loss)
• PPE = pumping plant efficiency
• PCF = a factor to convert energy use from units of force x distance to kWh
PCFPPE
TDHsavingswaterySavingsElectricit
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Energy Savings Energy Savings CalculatorCalculator
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Summary of Phase II Summary of Phase II FindingsFindings
Other Studies: Review of 11 other studied of SIS show water savings in the range of 7% to
30%.
Variations in crop types, methodology, location, study design and sample sizes make comparison difficult. Alfalfa is the prominent crop (31% of irrigated acres), followed by wheat (17%), vegetables (10%), corn (15%), and potatoes (7%).
Phase II Results: Water savings are approximately 10%
Energy Savings are approximately 13.1%
Caveats: The results are on the conservative side given the location of the study.
Water management techniques used by the treatment group were more rigorous than normal SIS practices.