Dennis Pittenger - UC Agriculture & Natural ResourcesSIMPLE IRRIGATION WITH ETo Dennis Pittenger...
Transcript of Dennis Pittenger - UC Agriculture & Natural ResourcesSIMPLE IRRIGATION WITH ETo Dennis Pittenger...
SIMPLE IRRIGATION WITH ETo
Dennis Pittenger Area Environmental Horticulturist
University of California Cooperative Extension
Los Angeles County/UC Riverside
Presentation © 2013 Dennis Pittenger
Dennis Pittenger Area Environmental Horticulturist [email protected] Phone: 951.827.3320 CENTER FOR LANDSCAPE & URBAN HORTICULTURE <www.ucanr.edu/cluh>
• B.S. & M.S. Horticulture, Ohio State University
• 32 years experience
– Landscape & urban horticulture
– Education and applied research programs
– Landscape irrigation mgt., plant water needs, weather-based irrigation control
– Presentations, workshops, publications, Web
. • Los Angeles County/UC Riverside
Quiz Answers
1. Evapotranspiration
2. True
3. True
4. True
5. True
6. False
7. False
8. True
9. True
10. 80%; 50% 10/16/13
.
• Los Angeles County/UC Riverside
Goals • Understand ETo – what it is, how it works.
• Review research-based insights on landscape water needs.
• Understand plant water demand estimation principles and variables.
• Learn simple, accurate ETo-based method to estimate accurate plant factors, water budgets, irrigation and schedules.
• Los Angeles County/UC Riverside
Useful Reference Materials • U.C.C.E. Center for Landscape and Urban Horticulture
– www.ucanr.edu/cluh (Landscape Water Management tab on left)
• Irrigation Association’s Landscape Irrigation Auditor Book, 2nd Ed. 2011. Chapter 7 and Appendix D.
• U.C. Cooperative Extension Handbook: Landscape Irrigation System Evaluation and Management. (D. Shaw and D. Pittenger, 2009)
– www.ucanr.edu/cluh (Landscape Water Management tab on left)
• California Dept. of Water Resources – CIMIS
– CIMIS (California Irrigation Management Information System)
– http://www.cimis.water.ca.gov/cimis
• Los Angeles County/UC Riverside
Useful Equations
Inches = Gallons ÷ (Sq. Ft. × 0.62)
Gallons = Inches × Sq. Ft. × 0.62
• Los Angeles County/UC Riverside
Landscapes require irrigation when…..
…..performance expectations exceed plant adaptation to precipitation
Expectations and Design Intent
determine landscape water need
Demand for Climate-based Landscape Water Need Estimates
Water budgets & tiered pricing
State & local conservation ordinances
‘Green’ building development programs, standards, codes
Smart irrigation controllers
Sustainable landscapes
U.S. EPA WaterSense
Save water and money
Landscape Water Conservation Programs
Visual courtesy of B. Mecham, Irrigation Assoc.
Common Provisions
Unique arbitrary procedures to set landscape water budget or need
Reduced turfgrass
Native plants
Limited or no potable water for landscape
Use of alternative water sources
reclaimed, stored precipitation, graywater
Demand for Climate-based Landscape Water Need Estimates
Water budgets
State & local conservation ordinances
“Green” development standards & codes
Smart irrigation controllers
Sustainable landscapes
U.S. EPA ‘Water Sense’
Save water
Save money
Why & How Plants Use Water
• Water loss is essential!!
• Maintain structure
• Photosynthesis & physiological processes
• Cooling (transpiration)
• Transports minerals & nutrients
Why & How Plants Use Water
• SPAC:
Soil-Plant-Air-Continuum
• Creates pull
Transpiration
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Stomata
Evapotranspiration (ET)
Climate-based reference
Inches/day
ETo = estimated water use of well-watered cool-season turf
Calculated from weather data
Sunlight, temperature, RH, wind
ASCE Penman-Monteith equation
Based on field research with agricultural crops
ETo = Reference Evapotranspiration An estimate of environmental water demand
over a planted area
Reference Evapotranspiration
Real-time = ETo or ETo
Historical Average = ET or ETH
Data sources
www.cimis.water.ca.gov
On-sight local weather station
Climate-Based Water Budgets Adjustment of ETo
Basic Water Budget or Water Requirement
Gallons = ETo × AF × LA × 0.62
gallons = inches × % × sq. ft. × conversion
ETo = reference evapotranspiration; climate impact
AF = ETo adjustment factor
LA = sq. ft. landscape area
0.62 converts inches per sq. ft. to gallons [gal. ÷ (in. x sq. ft.)]
Mandated “conservation” water budget
Plant types & sites respond differently to climate
Water Use ≠ Water Requirement Plants may use more water than they need to meet
expectations
Why Adjust ETo?
Climate-Based Water Budgets
Maximum Applied Water Allowance or Budget
MAWA = ETo × ETAF × LA × 0.62 Gallons = inches × adjustm’t. factor × sq. ft. × conversion
ETAF set by water purveyor, ordinance, design prog. 0.7 Calif. Model Water Efficient Landscape Ordinance 0.4, 0.6, 0.8, 1.0 common
ETo = reference ET ETAF = ET adjustment factor LA = landscape area 0.62 converts inches per sq. ft. to gallons [gal. ÷ (in. x sq. ft.)]
Climate-Based Water Budgets Need reliable plant factor estimates
Basic Water Budget or Water Requirement
Gallons = ETo × PF, KL , or Kc × LA × 0.62
gallons = inches × % × sq. ft. × conversion
ETo = reference evapotranspiration; climate impact
PF, KL, Kc = plant material adjustment factor LA = sq. ft. landscape area
0.62 converts inches per sq. ft. to gallons [gal. ÷ (in. x sq. ft.)]
KL = KPLANTS × KVEG. DENSITY × KMICROCLIMATE
KPLANTS from WUCOLS or list
KVEG. DENSITY and KMICROCLIMATE assigned by user
Landscape Coefficient (KL)
Typical ETo Adjustment Calculation
PROS
Source of numbers
Categories by climate zone and water use
Includes numerous spp.
Hardcopy and on-line
CONS
Not science based
Data not reliable
False sense of precision
Complex and perplexing to use
Not readily revised
WUCOLS Water Use Classification of Landscape Species
Simplified Landscape Irrigation Demand Estimation
S L I D E …..a new paradigm
for selecting Plant Factors..…
Principles:
Plant factors accurately estimated by broad plant type categories based on science and research
Landscape water need estimated by weighting sq. ft. of each plant type present
SLIDE Paradigm
SLIDE Features
Simple to understand & use
Replaces need for huge data base
Reduces number of factors or variables
Accommodates new plants
Scientifically & conceptually sound
Assimilation and application of ≈20 yrs. of data
Scientifically traceable
Provides reliable numbers for calculations
Wide geographic & climatic application
Current Development Status of SLIDE
Presenting to key stakeholders and decision makers
Electronic discussion system among researchers
Preparing technical manuscript to establish scientific merit
SLIDE Leaders
Roger Kjelgren – Utah State University
Richard Beeson – University of Florida
David Shaw – University of California
Dennis Pittenger – University of California
S623: Standardized Procedure for Determining Landscape Plant Water Requirements
Am. Society of Agricultural &
Biological Engineers (ASABE)
SLIDE concepts integrated
National Standard Being Developed
KL = KPLANTS × KVEG. DENSITY × KMICROCLIMATE
Landscape Coefficient (KL)
SLIDE Rules
Estimating Plant Water Needs Through Science
Define a reference for plant water use that is a function of climate (ETo)
Compare water needed to maintain given plant with reference amount
Express plant water need as % of reference
Plant Factor (PF) – acceptable appearance, function
Crop Coefficient (Kc) – optimum growth or yield
Estimating Plant Water Needs Through Science
Estimating Landscape Water Needs Using ETo
Assumptions:
Landscapes need/use water like ag. crops
Plant water needs change in lockstep with changes in ETo
Plant canopy is uniform
Same or similar plants across landscape
Ability to irrigate the landscape plants uniformly
ETo Approach OK With Turf
Visual courtesy of R. Kjelgren, Utah St. Univ.
Turfgrass Irrigation Needs
Cool-season Kc:
80% ETo annual avg.
(60% ETo minimum)
Warm-season Kc:
60% ETo annual avg.
(40% ETo minimum)
Field Studies on Landscape Plants’ Water Needs in California
79 plant species to date
33 trees, 12 groundcovers, 34 shrubs
Locations – no summer rainfall
Inland valley – 28 trees
South Coastal – 28 shrubs, 9 groundcovers, 5 trees
Low Desert – 6 shrubs, 3 groundcovers
Standard Research Approach
Minimum water needed for acceptable performance/appearance (%ETo = PF)
Apply multiple % ETo treatments
Irrigate when:
Σ(daily ETo × trtmt. %) = depletion target
Evaluate plant performance Aesthetics
Growth
Assumption
Visual courtesy of R. Kjelgren, Utah St. Univ.
Center for Landscape & Urban Horticulture University of California Cooperative Extension
Phormium tenax Aesthetic Quality Ratings
0.0
2.0
4.0
6.0
8.0
LSD 0.05
0.36 ETo
0.18 ETo
0 ETo
Phormium tenax
Center for Landscape & Urban Horticulture University of California Cooperative Extension
Center for Landscape & Urban Horticulture University of California Cooperative Extension
Arbutus unedo Aesthetic Quality Ratings
0.0
2.0
4.0
6.0
8.0
LSD 0.05
0.36 ETo
0.18 ETo
0 ETo
Center for Landscape & Urban Horticulture University of California Cooperative Extension
Salvia leucantha Aesthetic Quality Ratings
0.0
2.0
4.0
6.0
8.0
0.36 ETo
0.18 ETo
0 ETo
Center for Landscape & Urban Horticulture University of California Cooperative Extension .
Pyracantha ‘Santa Cruz’ Aesthetic Quality Ratings
0.0
2.0
4.0
6.0
8.0
0.36 ETo
0.18 ETo
0 ETo
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
Jan-Feb Mar-Apr May-Jun Jul-Aug Sep-Oct Nov-Dec
Cassia (Senna) 2007
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
Jan-Feb Mar-Apr May-Jun Jul-Aug Sep-Oct Nov-Dec
Star Jasmine 2007
20% and 40% are the same
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
Jan-Feb Mar-Apr May-Jun Jul-Aug Sep-Oct Nov-Dec
Juniper 'Sea Green' 200720%
40%
60%
80%
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
Jan-Feb Mar-Apr May-Jun Jul-Aug Sep-Oct Nov-Dec
Lantana 2007
Groundcovers, Trees, Shrubs
Woody plant performance & water need uncoupled with ETo
ETo × PF model cannot precisely estimate non-turf water need
Landscapes interactions too complex
Use more water than they need
Traditional landscape plants perform acceptably in with low to mod. water
Typically acceptable 30-60% of ETo
Less water may limit growth, not quality
Discrepancies with WUCOLS
Center for Landscape & Urban Horticulture University of California Cooperative Extension
Using & Adjusting PF & Kc Values
0.00
0.20
0.40
0.60
0.80
1.00
W
C
More Leaves & Growth High Expectations
Less Leaves & Growth Low Expectations
Turf Gc-Sh-Tr-Fl
Center for Landscape & Urban Horticulture University of California Cooperative Extension
Copyright © 2010-2013 D. Shaw and D. Pittenger
SLIDE Rules
Landscape plant water USE ≠ NEED
Plants often use more than they need
Meet minimum expectations in a range of % ETo
ETo concept has limited accuracy in landscapes
Landscape plants tolerate managed drought
Most non-turf plants need near 50% ETo
Plant factors accurately estimated by categorizing plant
SLIDE Rules (DRAFT)
Categories of Water Need
Turfgrass = 60% ETo (w-s) / 80% ETo (c-s)
Tree/Shrub/Groundcover/Vine = 50% ETo
Herbaceous Perennial Flowers & Foliage = 70% ETo
Annual-Perennial Flowers/Foliage = 80% ETo
Low Expectations/Desert Adapted = 30-40% ETo
WUCOLS Analysis
WUCOLS ZONE 1 2 3 4 5 6 AVG.
# of species appropriate to
zone 1602 1088 1969 1185 529 820 1199
% High Water Needs
0.7 – 0.9 ETo 5 6 5 9 7 8 7 (84)
% Medium Water Needs
0.4 - 0.6 ETo 51 52 57 57 66 68 59 (707)
% Low Water Needs
0.1 – 0.3 ETo 38 36 31 32 25 24 31 (372)
% Very Low Water Needs
< 0.1 ETo 7 5 7 3 2 0.5 4 (48)
Control Total 101 99 100 101 100 100.5
(WUCOLS III, 2000)
Estimating Landscape Water Requirement
Accurate and Simple Equation
Gallons = ETo × PF × LA × 0.62
gallons = inches × % × sq. ft. × conversion
ETo = reference evapotranspiration; climate impact
PF = plant material adjustment factor
LA = sq. ft. landscape area
0.62 = converts depth to volume [gal. ÷ (in. x sq. ft.)]
Leaf area influences landscape water demand
Incomplete Canopy Effects & Consideration
Crown projection area × ETo × PF
Guidelines for new or sparsely planted landscapes
SLIDE Rules
PF low:
fewer leaves
PF high: more leaves
Visual courtesy of R. Kjelgren, Utah St. Univ.
Applying SLIDE Rules in Design
• Design sq. ft. of turf desired
– PF = 0.6 or 0.8 for good appearance
• Assign PF’s for primary plant type in other hydrozones
– Reduce <20% with persistent shade
• ETo × PF × sq. ft. per zone
• Sum all zones’ water needs
• Set water requirement or compare to budget or allocation
• Los Angeles County/UC Riverside
(D. Shaw, 2010)
Applying SLIDE Rules Established Landscapes
Landscape Water Budget or Water Need
Gallons = ETo × ∑(PF × LA)1-x × 0.62
∑ = (PF1 × LA1)+ (PF2 × LA2) + (PF3 × LA3)…..
Divide each zone by DU
• ETo = reference evapotranspiration, CIMIS, etc.; climate impact
• PF = plant material factor (turf, shrub-tree-vine-gc, flowers, etc.)
• LA = sq. ft. landscape area
• 0.62 = converts depth to volume [gal. ÷ (in. x sq. ft.)]
Applying SLIDE Rules New Plantings, or Wide-Spaced Plants,
<80% Canopy Cover
Landscape Water Budget or Water Need
Gallons = ETo × ∑(PF × CA)1-x × 0.62
∑ = (PF1 × CA1) + (PF2 × CA2) + (PF3 × CA3)…..
Divide each zone by DU
• ETo = reference evapotranspiration, CIMIS, etc.; climate impact
• PF = plant material factor (turf, shrub-tree-vine-gc, flowers, etc.)
• CA = sq. ft. of canopy projection (π × r2)
• 0.62 = converts depth to volume [gal. ÷ (in. x sq. ft.)]
Useful Equations
Inches = Gallons ÷ (Sq. Ft. × 0.62)
Gallons = Inches × Sq. Ft. × 0.62
• Los Angeles County/UC Riverside
Applying SLIDE Rules #1 10,000 sq. ft. landscape with 500 sq. ft. patio + 250 sq. ft. walkway
• Allocation or Budget (MAWA) = ETo × AF × Sq. Ft. × 0.62 • Gal. = 44 in. × 0.7 × 9,250 sq. ft. × 0.62 = 176,638 gallons = 31 in.
• Required = ETo × ∑[(PF × LA ÷ DU)1 + (PF × LA ÷ DU)2 …]× 0.62 (= tall fescue + mixed trees, shrubs, groundcovers + color beds) (= 25% + 70% + 5%) = 44 in. × ∑[(0.8 × 2,300 ) + (0.5 × 6,450) + (0.8 × 500)] × 0.62 = 44 in. × ∑[(1,840 ÷ 0.7) + (3,225 ÷ 0.85) + (400 ÷ 0.75)] × 0.62 = 44 in. × [2,629 + 3,794 + 533] × 0.62 = 189,760 gallons = 33 inches
• About 13,000 gallons or 2 inches Over Budget!!!
Applying SLIDE Rules #2 7,500 sq. ft. landscape, 20 trees with 24 diameter canopies, drip irr.
• Allocation or Budget (MAWA) = ETo × AF × Sq. Ft. × 0.62 • Gal. = 44 in. × 0.7 × 7,500 sq. ft. × 0.62 = 143,220 gallons = 31 in.
• Required = ETo × ∑[(PF × LA ÷ DU)1 + (PF × LA ÷ DU)2 …]× 0.62 (= tree #1 + tree #2 + tree #3 + etc.) = ETo × ∑(𝐴𝑟𝑒𝑎 = 𝜋𝑟2 trees #1 to #20), then multiply by PF OR, = ETo × Avg. tree canopy area × 20, then multiply by PF = 44 in. × 3.14 × 144 s.f. × 0.5 × 0.62 = 6167 gal. per tree = 6167 gal. per tree × 20 trees = 123,340 gallons = 123,340 gallons ÷ 0.85 = 145,106 gallons = 31 inches
• About 1,886 gallons or 0.4 inches Over Budget!!!
Options to Reduce Water Needs
• Improve DU
• Adjust plant spp. mix
– Turf = 31 gal./sq. ft.
– G-S-T = 16 gal./sq. ft.
– Color = 25 gal./sq. ft.
• Reduce planted area
• Lower expectations
Expectations Met & Water Conserved
Take Home
ETo model not highly accurate for landscapes
Exact Plant Factors not needed for non-turf plants
Non-turf plants perform acceptably over broad % of ETo
SLIDE provides simple, accurate PFs Assign Plant Factors by plant type
Determine sq. ft. of turf first
Adjust non-turf PF to meet performance expectations
Principles:
Based on science - plant factors accurately estimated by broad plant type categories
Landscape water need estimated by weighting sq. ft. of each plant type
SLIDE Paradigm
Dennis Pittenger Area Environmental Horticulturist
[email protected] Phone: 951.827.3320 Center for Landscape & Urban Horticulture <www.ucanr.edu/cluh>
• Los Angeles County/UC Riverside