SIMPLE IRRIGATION WITH ETo

Transcription

1 SIMPLE IRRIGATION WITH ETo Dennis Pittenger Area Environmental Horticulturist University of California Cooperative Extension Los Angeles County/UC Riverside Presentation 2013 Dennis Pittenger

2 Dennis Pittenger Area Environmental Horticulturist Phone: CENTER FOR LANDSCAPE & URBAN HORTICULTURE < 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

3 Quiz Answers 1. Evapotranspiration 2. True 3. True 4. True 5. True 6. False 7. False 8. True 9. True %; 50% 10/16/13. Los Angeles County/UC Riverside

4 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

5 Useful Reference Materials U.C.C.E. Center for Landscape and Urban Horticulture (Landscape Water Management tab on left) Irrigation Association s Landscape Irrigation Auditor Book, 2nd Ed Chapter 7 and Appendix D. U.C. Cooperative Extension Handbook: Landscape Irrigation System Evaluation and Management. (D. Shaw and D. Pittenger, 2009) (Landscape Water Management tab on left) California Dept. of Water Resources CIMIS CIMIS (California Irrigation Management Information System) Los Angeles County/UC Riverside

6 Useful Equations Inches = Gallons (Sq. Ft. 0.62) Gallons = Inches Sq. Ft Los Angeles County/UC Riverside

7 Landscapes require irrigation when....performance expectations exceed plant adaptation to precipitation Expectations and Design Intent determine landscape water need

8 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

9 Landscape Water Conservation Programs Visual courtesy of B. Mecham, Irrigation Assoc.

10 Standards Organizations

11 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

12 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

13 Why & How Plants Use Water Water loss is essential!! Maintain structure Photosynthesis & physiological processes Cooling (transpiration) Transports minerals & nutrients

14 Why & How Plants Use Water SPAC: Soil-Plant-Air-Continuum Creates pull Transpiration H + H + O - H + H + O - H + H + O - H + H + O - H + H + O - H + H + O - H + H + O - H + H + O - Stomata

15 Evapotranspiration (ET)

16 ETo = Reference Evapotranspiration An estimate of environmental water demand over a planted area 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

17 Reference Evapotranspiration Real-time = ETo or ETo Historical Average = ET or ETH Data sources On-sight local weather station

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19 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.)]

20 Why Adjust ETo? 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

21 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.)]

22 Climate-Based Water Budgets Need reliable plant factor estimates Basic Water Budget or Water Requirement Gallons = ETo PF, K L, or Kc LA 0.62 gallons = inches % sq. ft. conversion ETo = reference evapotranspiration; climate impact PF, K L, Kc = plant material adjustment factor LA = sq. ft. landscape area 0.62 converts inches per sq. ft. to gallons [gal. (in. x sq. ft.)]

23 Typical ETo Adjustment Calculation Landscape Coefficient (K L ) K L = K PLANTS K VEG. DENSITY K MICROCLIMATE K PLANTS from WUCOLS or list K VEG. DENSITY and K MICROCLIMATE assigned by user

24 WUCOLS Water Use Classification of Landscape Species 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

25 Simplified Landscape Irrigation Demand Estimation S L I D E..a new paradigm for selecting Plant Factors..

26 SLIDE Paradigm 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

27 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

28 Current Development Status of SLIDE Presenting to key stakeholders and decision makers Electronic discussion system among researchers Preparing technical manuscript to establish scientific merit

29 SLIDE Leaders Roger Kjelgren Utah State University Richard Beeson University of Florida David Shaw University of California Dennis Pittenger University of California

30 National Standard Being Developed S623: Standardized Procedure for Determining Landscape Plant Water Requirements Am. Society of Agricultural & Biological Engineers (ASABE) SLIDE concepts integrated

31 SLIDE Rules Landscape Coefficient (K L ) K L = K PLANTS K VEG. DENSITY K MICROCLIMATE

32 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

33 Estimating Plant Water Needs Through Science

34 Estimating Landscape Water Needs Assumptions: Using ETo 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

35 ETo Approach OK With Turf Visual courtesy of R. Kjelgren, Utah St. Univ.

36 Turfgrass Irrigation Needs Cool-season Kc: 80% ETo annual avg. (60% ETo minimum) Warm-season Kc: 60% ETo annual avg. (40% ETo minimum)

37 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

38 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

39 Visual courtesy of R. Kjelgren, Utah St. Univ. Assumption

40 Phormium tenax Aesthetic Quality Ratings LSD ETo 0.18 ETo 0 ETo 0.0 Center for Landscape & Urban Horticulture University of California Cooperative Extension

41 Phormium tenax Center for Landscape & Urban Horticulture University of California Cooperative Extension

42 Arbutus unedo Aesthetic Quality Ratings LSD ETo 0.18 ETo 0 ETo 0.0 Center for Landscape & Urban Horticulture University of California Cooperative Extension

43 Salvia leucantha Aesthetic Quality Ratings ETo ETo 0 ETo 0.0 Center for Landscape & Urban Horticulture University of California Cooperative Extension

44 Pyracantha Santa Cruz Aesthetic Quality Ratings ETo 0.18 ETo 0 ETo 0.0 Center for Landscape & Urban Horticulture University of California Cooperative Extension.

45 Cassia (Senna) 2007 Jan-Feb Mar-Apr May-Jun Jul-Aug Sep-Oct Nov-Dec Star Jasmine % and 40% are the same Jan-Feb Mar-Apr May-Jun Jul-Aug Sep-Oct Nov-Dec Juniper 'Sea Green' % 40% 60% 80% Lantana Jan-Feb Mar-Apr May-Jun Jul-Aug Sep-Oct Nov-Dec Jan-Feb Mar-Apr May-Jun Jul-Aug Sep-Oct Nov-Dec

46 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

47 Using & Adjusting PF & Kc Values Turf Gc-Sh-Tr-Fl More Leaves & Growth High Expectations C W 0.20 Less Leaves & Growth Low Expectations 0.00 Copyright D. Shaw and D. Pittenger Center for Landscape & Urban Horticulture University of California Cooperative Extension

48 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

49 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

50 WUCOLS Analysis WUCOLS ZONE AVG. # of species appropriate to zone % High Water Needs ETo (84) % Medium Water Needs ETo (707) % Low Water Needs ETo (372) % Very Low Water Needs < 0.1 ETo (48) Control Total (WUCOLS III, 2000)

51 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.)]

52 SLIDE Rules Leaf area influences landscape water demand Incomplete Canopy Effects & Consideration Crown projection area ETo PF Guidelines for new or sparsely planted landscapes

53 PF high: more leaves PF low: fewer leaves Visual courtesy of R. Kjelgren, Utah St. Univ.

54 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

55 (D. Shaw, 2010) Los Angeles County/UC Riverside

56 Applying SLIDE Rules Established Landscapes Landscape Water Budget or Water Need Gallons = ETo (PF LA) 1-x 0.62 = (PF 1 LA 1 )+ (PF 2 LA 2 ) + (PF 3 LA 3 ).. 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.)]

57 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 = (PF 1 CA 1 ) + (PF 2 CA 2 ) + (PF 3 CA 3 ).. 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 r 2 ) 0.62 = converts depth to volume [gal. (in. x sq. ft.)]

58 Useful Equations Inches = Gallons (Sq. Ft. 0.62) Gallons = Inches Sq. Ft Los Angeles County/UC Riverside

59 Applying SLIDE Rules #1 10,000 sq. ft. landscape with 500 sq. ft. patio sq. ft. walkway Allocation or Budget (MAWA) = ETo AF Sq. Ft Gal. = 44 in ,250 sq. ft = 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) + ( )] 0.62 = 44 in. [(1, ) + (3, ) + ( )] 0.62 = 44 in. [2, , ] 0.62 = 189,760 gallons = 33 inches About 13,000 gallons or 2 inches Over Budget!!!

60 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 Gal. = 44 in ,500 sq. ft = 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 = πr 2 trees #1 to #20), then multiply by PF OR, = ETo Avg. tree canopy area 20, then multiply by PF = 44 in s.f = 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!!!

61 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

62 Expectations Met & Water Conserved

63 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

64 SLIDE Paradigm 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

65 Dennis Pittenger Area Environmental Horticulturist Phone: Center for Landscape & Urban Horticulture < Los Angeles County/UC Riverside