Water Budgeting in California - MWELO

Transcription

1 Water Budgeting in California - MWELO 1

2 What Is a Water Budget? A budget is generally a list of all planned expenses and revenues. It is a plan for saving and spending. A water budget is a plan for managing water use and saving. Tracks planned water use versus actual water use. A water budget helps manage costs and improves site maintenance and efficiency.

3 How Plants Use Water Evapotranspiration (ET) the combined process of soil evaporation and plant transpiration Soil Evaporation is the direct evaporation of water from the surface of the soil into the atmosphere 3

4 Plant Transpiration Plant Transpiration is the movement of moisture from the plant to the air through tiny pores in the leaves known as stomates. The water enters the plants through the roots in a liquid form and leaves the plants through the stomates in gaseous form. 4

5 Reference ET (Eto) A standard measurement of environmental parameters which affect the water use of plants. Expressed in inches per day, month or year and is an estimate of the evapotranspiration of a large field of 4-7 tall, cool season grass that is well watered Set at 1.0 or 100% Reference evapotranspiration is used in MWELO as the basis of determining the Maximum Applied Water Allowance so that regional differences in climate can be accommodated 5

6 Crop Coefficients (Crop k) = Plant Factor The Reference Crop has a Value of 1.0. How do other crops compare to the reference crop? Cool Season Turf =.8* Warm Season Turf =.6* Ground Cover =.6* Shrubs (w/o GC) =.5* Drought Tolerant & Natives =.3* *Average values are based on results compiled on over 1000 site inspections performed in California by Gary Kah and Chris Willig (Original writers of the WMCP Study Guide Copyright 2006) 6

7 Hydrozone Grouping of plants with similar watering requirements so that they can be watered correctly High Water, Medium Water, Low Water, Very Low A list of plants by water use classification can be found in A Guide to Estimating Water Needs of Landscape Plantings in California (also referred to as WUCOLS) by the CA Dept of Water Resources 7

8 How do we measure usage? Water Meters How we measure water usage Three Types cubic feet, gallons and flow meter Flow indicator is a triangle on the face of the meter that moves when water is passing through the meter. On a dedicated irrigation meter with the irrigation system off and a moving flow indicator can indicate a leak 8

9 Using a Water Budget: Calculate how much water the site actually needs Need site acreage Use formula to estimate water requirement Track how much water is used and compare with the water budget water meter

10 Model Water Efficient Landscape Ordinance (MWELO) - MAWA Maximum Applied Water Allowance (MAWA): means upper limit of annually applied water for an established landscape area and is based upon: Regional Reference Evapotranspiration (Eto) A conversion from inches/acre to gallons/year Evapotranspiration Adjustment Factor (ETAF) Size of Landscaped Area (LA) Special Landscaped Areas (SLA) MAWA CALCULATION FROM APPENDIX B Eto x.62 x [(ETAF x LA) + (1-ETAF x SLA)]

11 Maximum Applied Water Allowance with No SLA Means a water budget (annual) Sets a Not to exceed goal Creates a process to quantify and adjust Where: ETo x.62 x (Et Adjustment Factor x Landscape Area) Eto = Evapotranspiration (transpiration + evaporation).62 = Conversion to Gallons (from inches per acre to gallons per year) ETAF = Evapotranspiration Adjustment Factor 55% (.55) for residential and 45% (.45) for commercial of Eto for new landscapes and 80% (.80) for existing landscapes LA = Landscaped Area in Square Feet

12 MAWA Examples MAWA = Eto x.62 x [(ETAF x LA) + (1-ETAF x SLA)] Eto = 44 (Santa Rosa).62 = conversion to gallons ETAF =.55 for residential properties.45 for non-residential properties LA = 2000 square feet SLA = None Residential MAWA = 44 /year x.62 x (.55 x 2000) = 30,008 gallons per year Non-residential MAWA = 44 x.62 x (.45 x 2000) = 24,552 gallons per year

13 Estimated Total Water Use (ETWU) Means - the estimated sum of water use calculated for each hydrozone (irrigation stations) areas (HA) in a landscape. Sum of HA s shall not exceed the MAWA. Estimated Total Water Use (ETWU) must be determined for every irrigation station/zone then added together to compare to the MAWA Evapotranspiration Adjustment Factor (ETAF) = Plant Factor (PF) Irrigation Efficiency (IE) ETWU CALCULATION FROM APPENDIX B Eto x.62 x ETAF x Area Is the same as Eto x.62 x PF x HA IE

14 Estimated Total Water Usage ETWU = Eto x.62 x PF x HA Eto = Evapotranspiration (transpiration + evaporation).62 = Conversion to Gallons PF = Plant Type Water Needs = High (.9-.7), Moderate (.6-.4), Low (.3-.1), Very Low (.1 and less) HA = Hydrozone Area = Size in Square Footage IE = Irrigation Efficiency (Beneficial water used/total water used) and set at.81 for Drip and.75 for Spray IE MWELO APPENDIX B shows that the PF/IE creates an ETAF for the hydrozone which is then multiplied by the HA

15 ETWU Example Zone 1 ETWU = Eto x.62 x PF x HA Eto = 44 (Santa Rosa).62 = Conversion to Gallons PF =.80 (lawn area) Hydrozone Area = 500sf IE =.75 (Spray Irrigation) IE ETWU for Zone 1 - Lawn Area 44 /year x.62 x.8 x x.62 x 1.07 x 500 = 14,595 gal/year

16 ETWU Example Zones 2, 3 and 4 Eto = 44 (Santa Rosa).62 = Conversion to Gallons PF =.3 (Natives) and.5 (Trees and Shrubs) Hydrozone Area = 500sf per zone IE =.81 (Drip System) ETWU for Zone 2 Tree and Shrub Area 44 /year x.62 x.5 x 500 so 44 x.62 x.617 x 500 = 8,416 gl/yr.81 ETWU for Zone 3 Low Water Use Natives 44 /year x.62 x.3 x 500 so 44 x.62 x.37 x 500 = 5,047 gl/yr.81 ETWU for Zone 4 Low Water Use Natives 44 /year x.62 x.3 x 500 so 44 x.62 x.37 x 500 = 5,047 gal/yr.81

17 MAWA vs ETWU Landscaped Area = 2000 square feet Zone 1: Lawn 500sf = 14,595 gallons Zone 2: Trees/Shrubs 500sf = 8,416 gallons Zone 3 & 4: 1000sf = 10,094 gallons Total ETWU: 33,105 gallons per year MAWA = 30,008 gallons per year Over Budget by 3,097 gallons This landscape will not meet MWELO requirements!

18 MAWA vs ETWU What needs to be done to meet MAWA? Reduce size of lawn or eliminate Change tree and shrub area to low water using natives Use plants w/a PF of very Low Maybe a combination of factors Add a Special Landscape Area (SLA)

19 Recalculating MAWA with an SLA Special Landscape Areas (SLA) are those areas dedicated solely for edible plants, recreational areas and areas irrigated by alternate sources of water and water features using recycled water SLA CALCULATION: (1 ETAF) x SLA (in sq ft) This calculation is added onto the MAWA calculation when an SLA is included MAWA = Eto x.62 x [(ETAF x LA) + ((1-ETAF)xSLA)]

20 Recalculating MAWA w/an SLA MAWA = Eto x.62 x [(ETAF x LA) + ((1-ETAF ) x SLA)] Eto = 44 (Santa Rosa).62 = conversion to gallons ETAF =.55 for residential properties.45 for non-residential properties LA = 2100 square feet (Total Landscape Area incl SLA) SLA = 100 MAWA = 44 /year x.62 x [(.55 x 2100) + ((1-.55) x 100)] 44 x.62 x [(.55 x2100) + (.45 x 100) = 44 x.62 x ( ) = 32,736 gallons per year

21 ETWU Example SLA (Residential) Eto = 44 (Santa Rosa).62 = Conversion to Gallons PF =.8 (lawn).5 (Trees and Shrubs),.1 (very low water use) and 1.0 (SLA) Hydrozone Areas = 500sf (lawn), 500sf (Trees & shrubs), 1000sf (very low) SLA = 100sf IE =.81 (Drip System) or.75 (spray system) TOTAL LANDSCAPE AREA = 2100sq ft ETWU for Zone 1 - Lawn Area 44 /year x.62 x.8 x 500 so 44 x.62 x 1.07 x 500 = 14,595 gal/yr.75 ETWU for Zone 2 Tree and Shrub Area 44 /year x.62 x.5 x 500 so 44 x.62 x.617 x 500 = 8,416 gal/yr.81 ETWU for Zone 3 Very Low Water Use 44 /year x.62 x.1 x 1000 so 44 x.62 x.123 x 1000 = 3,355 gal/yr.81 ETWU for Zone 4 Special Landscape Area 44 /year x.62 x (1.0 x 100) = 2,728 gal/yr

22 Yearly MAWA vs ETWU with Special Landscape Area (SLA) Zone 1: 500sf = 14,595 gal/year Zone 2: 500sf = 8,416 gal/year Zone 3: Very 1000sf = 3,355 gal/year Zone 4: 100sf = 2,728 gal/year Total size of landscape 2100 square feet Total ETWU with an SLA = 29,094 gallons per year MAWA incl (SLA) = 32,736 gal/year

23 MAWA = ETWU with an SLA SLA = Special Landscape Area (edible plants, recreation areas, grey water or recycled water use) Zone 1 = 14,595 gal/year lawn Area Zone 2 = 8,416 gal/year Trees & Shrub Area Zone 3 = 3,355 gal/year Very Low Water Use Area Zone 4 (SLA) = 2,728 gal/year Special Landscape Area Total ETWU = 29,094 gallons/year MAWA w/sla = 32,736 gallons/year (Under Budget by 3,642 gallons) This landscape will meet MWELO requirements!

24 Let s Try Some Scenarios Calculate the MAWA for the following residential project: ETo = 44 ETAF =.55 LA = 2,000sf Remember the Formula: MAWA = ETo x.62 x ETAF X LA = gallons/year 44 x.62 x.55 x 2000 = 30,008 gal/year

25 Let s Try Some Scenarios Calculate the MAWA with an SLA for the following non-residential project: ETo = 44 ETAF =.45 LA = 2,000sf SLA = 500 Remember the Formula: ETo x.62 x [(ETAF X LA) + ((1-ETAF)x SLA)] = gal/year

26 Let s Try Some Scenarios Calculate the MAWA for the following non-residential project: ETo = 44 ETAF =.55 LA = 2,000sf SLA = 500 Remember the Formula: 44 x.62 x [(.45 X 2000) + ((1-.45) x 500)] 44 x.62 x ( ) 44 x.62 x 1175 = 32,054 gallons/year

27 Now Let s Try THE ETWU Calculate the Estimated Total Water Use (ETWU): ETo = = Conversion to Gallons PF (Plant Factor) for Zone #1 = Lawn (.8) HA = 500sf IE =.75 - Spray Irrigation Remember the Formula: ETWU = ETo x.62 x PF x HA IE

28 Now Let s Try THE ETWU Calculate the Estimated Total Water Use (ETWU): ETo = = Conversion to Gallons PF for Zone #1 = Lawn(.8) HA = 500sf IE =.75 - Spray Irrigation Remember the Formula: ETWU = 44 x.62 x.8 x ETWU = 44 x.62 x 1.07 x 500 ETWU = 44 x.62 x 1.07 x 500 = 14,595 gallons/year

29 Now Let s Try THE ETWU Calculate the Estimated Total Water Use (ETWU) ETo = = Conversion to Gallons PF (Plant Factor) for Zone #2 = Trees and Shrubs(.5) HA = 500sf IE =.81 Drip Irrigation Remember the Formula: ETWU = 44 x.62 x.5 x ETWU = 44 x.62 x.617 x 500 ETWU = 44 x.62 x.617 x 500 = 8,416 gallons/year

30 Now Let s Try THE ETWU Calculate the Estimated Total Water Use (ETWU) ETo = = Conversion to Gallons PF for Zone #3 = Natives (.3) HA = 500sf IE =.81 - Drip Irrigation Remember the Formula: ETWU = 44 x.62 x.3 x ETWU = 44 x.62 x.37 x 500 ETWU = 44 x.62 x.37 x 500 = 5,047 gallons/year

31 Now Let s Try THE ETWU Calculate the Estimated Total Water Use (ETWU) ETo = = Conversion to Gallons PF for Zone #4 = Natives (.3) HA = 500sf IE =.81 - Drip Irrigation Remember the Formula: ETWU = 44 x.62 x.3 x ETWU = 44 x.62 x.37 x 500 ETWU = 44 x.62 x.37 x 500 = 5,047 gallons/year

32 MAWA vs. ETWU MAWA = 30,008 gallons per year ETWU : Zone #1 = 14,595 gallons Zone #2 = 8,416 gallons Zone #3 = 5,047gallons Zone #4 = 5,047 gallons ETWU = 33,105 gal/year This project WILL NOT meet MAWA OVER budget by 3,665 gallons per year