1.1 Reference
To determine how much water plants need, a measurement of how much water plants consume through
is needed.
is the transfer of water from land surface to the atmosphere through the combination of evaporation and plant transpiration. In the Reference
Method (ETo Method), water use by plants is estimated for a high-water-use grass cover crop (such as alfalfa) for which
can be directly measured. Monthly Reference ETo values for a high-water-use grass crop in Tucson have been tabulated in Table A-2.
MONTHLY REFERENCE
(Inches) | |||||||||||
Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
3.0 | 3.72 | 6.0 | 8.04 | 9.96 | 10.56 | 9.36 | 7.92 | 7.20 | 5.76 | 3.60 | 2.64 |
Line | DESCRIPTIONS OF WATER BUDGET COMPONENT | SOURCES FOR EACH
(WHIAs) | EXAMPLE WHIA |
PLANT WATER DEMAND
|
Line | DESCRIPTIONS OF WATER BUDGET COMPONENT | SOURCES FOR EACH
(WHIAs) | EXAMPLE WHIA |
PLANT WATER DEMAND
| |||
1 | Individual WHIA identifier | APPLICANT PROVIDES | WHIA - 1 |
2 | Plant water demand category for this WHIA | APPLICANT PROVIDE USING ADWR PLANT LIST | low |
3 | (square feet) for this WHIA. Add the canopies of understory, midstory and overstory plant areas to get total canopy for each WHIA. Assume 60% of mature plant size | APPLICANT PROVIDE. CAN BE BASED ON LANDSCAPE PLAN OR PLANT LIST | 1250 |
4 | Plant water demand per year (vertical feet of water per year per square foot of canopy) for this WHIA | APPLICANT USES APPROPRIATE NUMBER BASED ON PLANT WATER DEMAND CATEGORY FOR THIS WHIA | 1.7 |
5 | CALCULATE: Annual plant water demand for this WHIA based on (gallons) | = line 3 times line 4 times 7.48 gallons/cubic foot of water | 15,895 |
6 | OVERALL SUPPLY | ||
7 | WHIA area (square feet) | APPLICANT PROVIDE | 1000 |
8 | WHIA average depth (feet) | APPLICANT PROVIDES | 0.5 |
9 | CALCULATE: WHIA capacity (gallons) | line 7 times line 8 times 7.48 gallons/cubic foot of water | 3,740 |
10 | If is used: | ||
11 | Subwatershed identifier | APPLICANT | S-1 |
12 | Ratio of subwatershed area to needed to meet plant water demand in this WHIA in July through March (use March plant water demand as the indicator month) (no units) | APPLICANT USES APPROPRIATE NUMBER BASED ON PLANT WATER DEMAND CATEGORY FOR EACH WHIA | 3.85 |
13 | CALCULATE: Total ideally needed to meet plant water demand in March (square feet) | = line 3 x line 12 | 4,813 |
14 | Actual total designed for this WHIA including the WHIA area itself (square feet) | APPLICANT PROVIDE | 1500 |
15 | CALCULATE: Actual for this WHIA | = line 14 divided by line 3 | 1.20 |
16 | CALCULATE: Actual percent of plant water demand that will be met for this WHIA | = 64% times line 15 divided by line 12 | 20% |
17 | If is used: | ||
18 | Tank identifier | APPLICANT PROVIDES | T-1 |
19 | above or below ground? | APPLICANT PROVIDES | above |
20 | tank height (feet) | APPLICANT PROVIDES | 8 |
21 | tank diameter (feet) | APPLICANT PROVIDES | 6 |
22 | tank capacity (gallons) | APPLICANT PROVIDES | 1619 |
23 | tank location | APPLICANT PROVIDES | East corner |
24 | CALCULATE: Percent of plant water demand for this WHIA met by this tank | (Assume tank will be filled and emptied 4 times per year). Total water provided = 4 times line 22 divided by line 5 | 41% |
25 | CALCULATE: Percent of plant water demand for this WHIA met using harvested from passive systems and active systems (as applicable) | = line 16 + line 24 | 61% |
26 | TOTAL INFORMATION | ||
27 | Percent to total annual landscape demand met using harvested water | Prorate percent of supply based on area of each WHIA | 61% |
28 | capacity offsetting retention basin size capacity | APPLICANT PROVIDES | |