Any info on tweaking usage stats in the advanced settings for zones. I contacted tech-support but they said most of their information is AI and I should reach out to Community Support
I know my actual usage for the zone from gallons used on the water meter and also know each head is .6 in/hr. I need to calculate the area to put into the advanced setting. tech-support says.
To find the area (square feet), we need to rearrange the formula: Area (sq ft) = (Gallons Used per Hour × 96.25) ÷ Nozzle Inches Per Hour
Here is the calculation:
672 × 96.25 = 64,680
64,680 ÷ 0.60 = 107,800 sq ft
So you would enter 107,800 square feet in the Area field in your zone’s advanced settings.
I know this cannot be correct because my lot size is only about 10,000 ft.² I believe the correct way to calculate the area is.
To find the square footage of the irrigated area, you divide the total gallons used in one hour by the gallons per square foot equivalent of your nozzle’s application rate. [1]
1 inch of water applied over 1 square foot is equal to 0.623 gallons. [1, 2]
The Math Formula
Area(sq\ ft) = Total Gallons Used in One Hour divided by (Nozzle Inches Per Hour times 0.623)
A Quick Example
Let’s say your system emits 1 inch per hour and used 62.3 gallons in one hour:
Multiply the inches per hour by 0.623 1 times 0.623 = 0.623
Divide your total gallons used by that number: 62.3 divided by .623 = 100 sq. ft
my scenario would be
Calculate gallons per square foot:
0.6 inches per hour times 0.623 = 0.3738 gallons per sq ft
Divide total gallons by that rate:
672 gallons div 0.3738 = 1,797.75 square feet
My irrigated area is approximately 1,798 square feet
when I used 1,798 sq ft and .6 nozzle rate in the advanced settings on the rachio app, the gallons used in the rachio app for the zone were very close to the gallons used on my water meter.
does it sound like the correct way to calculate for area?
Why are you calculating area based on a fairly rounded flow rate, very rounded application rate, and time? You can easily measure the area of each zone. (I’m not sure area if even necessary for zones).
A bunch of the variables all do the same thing, just different ways, so you can skip them. For my settings, I leave my root depth at 4in for all zones, and efficiency at 100%. I set nozzle In/hr by calculating nozzle/area.
So all I really tweak is Allowed Depletion and Crop Coeff. First set the depletion to like 50% (this is how much moisture exists when watering occurs).
I set Crop Coeff by waiting until a heavy rain or watering so I know the soil is saturated (and Rachio knows that). Then when the soil is physically dry in each zone, I set the coeff (higher means more evaporation occurs), so that rachio calculates the zone moisture at 0%.
Then I just observe of next few months, and tweak those 2 numbers.
I really just want to calculate gallons used for each zone per hour. Calculating the area is very difficult because it is so irregular. Changing the Allowed Depletion and Crop Coeff doesn’t seem like it change the amount of gallons used per hour.
The known variables are gallons used per hour from the water meter and the manufacturer specs for inch per hour for my rotary heads
Your units are incorrect. Flow is usually specified (in Imperial units) in GPM (gallons per minute), and irrigation rates (precipitation rate, nozzle application rate) are specified as inches per hour.
That aside, the equation of interest is the calculation of precipitation rate from flow and area - two things you can actually measure - on any zone, regardless of how it’s equipped:
Precipitation rate (in/hr) = 96.25 x flow (gpm) / area (sq. ft.)
That precipitation rate is what you use to provide the “nozzle inches per hour” value for each zone. The calculation I believe you’re trying to do, without understanding why you’d measure area so indirectly is the reorganization of the rate calculation to look like:
area (sq ft) = 96.25 x flow (gpm) / rate (in/hr)
And with rate of 1 in/hr and flow of 62.3 gal/hr would be 96.25 x (62.3 / 60) gpm / 1 in/hr, or ≈100 sq. ft.
I think we are both getting the same end number for square feet by using different formulas
To find the square footage of the irrigated area, you divide the total gallons used in one hour by the gallons per square foot equivalent of your nozzle’s application rate.
1 inch of water applied over 1 square foot is equal to 0.623 gallons.
An layer of water 1” deep over an area of 1 square foot yields a volume of 0.0833 cubic feet, which is equivalent to approximately 0.623 US gallons
.6 in/hr (per mfg spec sheet per head)
672 gal/hr using my water meter
my formula would be
0.6 inches per hour times 0.623 = 0.3738 gallons per sq ft and
672gallons div 0.3738 = 1,797.75 square feet
your formula
And with rate of .6 in/hr and flow of 672 gal/hr would be 96.25 x (672 / 60) gpm / .6 in/hr, or ≈1796 sq. ft.
