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 Ventura County
 Code of Ordinances
 Division 8. Planning and Development
 Chapter 1.1. Zoning (Coastal)

  Appendix L5. EXAMPLES FOR CALCULATING THE WATER BUDGET  

Latest version.

  • Example 1:

    A hypothetical residential landscape project in Ventura, California, with an irrigated landscape area of 1,000 square feet; no special landscape area (SLA = 0).

    AppL5-1.png

    Hydrozone: Label each planting area polygon with a number or letter.

    Plant Water Use Types: Identify water demand for each hydrozone.

    Plant Factor : [] Plant factor range shall be as follows:

    •

    Low water use plants: 0.1 to 0.3

    •

    Moderate water use plants: 0.4 to 0.6

    •

    High water use plants: 0.7 to 1.0

    Hydrozone Plant Water Use Type(s) Plant Factor
    (PF)*     		Irrigation Method Irrigation Efficiency ETAF
    (PF/IE)     		Hydrozone Area (HA)
    (square feet)     		ETAF
    ×
    Area     		Estimated Total Water Use
    (ETWU)
    1 High 0.8 Drip 0.81 0.67 100 67 1807
    2 High 0.7 Drip 0.81 0.86 100 86 2319
    3 Medium 0.5 Drip 0.81 0.61 100 61 1645
    4 Low 0.3 Drip 0.81 0.37 350 130 3506
    5 Low 0.2 Drip 0.81 0.24 350 84 2265
    1,000
    (A)     		428
    (B)     		11,542

     

    Maximum Applied Water Allowance (MAWA)

    MAWA = (ETo) (0.62) [(ETAF × LA) + ((1-ETAF) × SLA)]

    Average ETWU = 0.55

    MAWA = (43.5) × (0.62) [(0.55 × 1,000 sf) + ((0.45 × 0)]

    MAWA = (43.5) × (0.62)[(550) + (0)]

    MAWA = (26.97) × [550]

    MAWA = 14,834 gallons

    To convert from gallons per year to hundred-cubic-feet per year:

    = 14,834/748

    (100 cubic feet = 748 gallons)

    = 19.83 hundred-cubic-feet per year

    Estimated Total Water Use (ETWU) (gallons per year)

    ETWU = ETo × 0.62 × ETAF × Area

    HA #1:  (43.5) × (0.62) × (0.67) × (100)
    [26.97] × [67] = 1,807

    HA #2:  (43.5) × (0.62) × (0.87) × (100)
    [26.97] × [87] = 2,346

    HA #3:  (43.5) × (0.62) × (0.61) × (100)
    [26.97] × [61] = 1,645

    HA #4:  (43.5) × (0.62) × (0.37) × (350)
    [26.97] × [130] = 3,506

    HA #5:  (43.5) × (0.62) × (0.24) × (350)
    [26.97] × [84] = 2,265

    ETWU = 11,569 gallons per year

    Compare ETWU with MAWA.

    MAWA = 14,834 gallons per year

    ETWU = 11,569 gallons per year

    ♦

    The ETWU (11,569 gallons per year) is less than MAWA (14,834 gallons per year).

    In this example, the water budget complies with the MAWA.

(Ord. No. 4492, § 9, 6-21-2016)