Spike's Calculators

# Water Application Rate Calculators

## Water Application Rate - Acres

Where H = the application rate; inches per hour
Q = flow rate; gallons per hour
K = one acre-inch of water = 27,154 gallons per acre
to get the conversion factor divide 27,154 ÷ 60 = 452.6667 (dividing an acre-inch by 60 minutes per hour)
A = area in acres
```
application rate inch per hour  =  flow rate (gallons per minute)  ÷  452.6667
area in acres
```
Example calculation :
```water flow rate= 6 gallons per minute (gpm)
area to irrigate = 1.8 acres (ac)
6 ÷ 452.6667 ÷ 1.8 = 0.0074  inch(es) per hour
to apply 1 inch of water would require 135 minutes of irrigation time```

### Water Application Rate - Acres

Flow Rate gal/min
Area ac
Run Time hrs
Irrigation Efficiency %
Number of Digits in Result #

#### Results:

 Application Rate in/hr Depth of Water Applied in Application Rate mm/hr Depth of Water Applied mm

#### Calculation

1. flow rate (gallons per minute)
2. area to irrigate (acres)
3. irrigation run time the amount of time the system is running in hours
4. irrigation efficiency

#### Results

1. the application rate in inches per hour
2. amount of water applied based on system run time in inches
3. the application rate in millimetres per hour
4. amount of water applied based on system run time in millimetres

## Water Application Rate - Square Footage

Where H = the application rate; inches per hour
Q = flow rate; gallons per hour
K = one square foot-inch of water = 0.62 gallons per square foot
to get the conversion factor divide 0.62 / 60 = 0.011167 (dividing a foot-inch by 60 minutes per hour)
```
application rate inch per hour  =  flow rate (gallons per minute)  ÷  0.011167
area in square feet
```
Example calculation:
```water flow rate= 6 gallons per minute (gpm)
area to irrigate =  600 square feet
6 /  0.011167 / 600 = 0.895 inch(es) per hour
to apply 1 inch of water would require 67 minutes of irrigation time```

### Water Application Rate - Square Footage

Flow Rate gal/min
Area ft²
Run Time hrs
Irrigation Efficiency %
Number of Digits in Result #

#### Results:

 Application Rate in/hr Depth of Water Applied in Application Rate mm/hr Depth of Water Applied mm

#### Calculation

1. flow rate (gallons per minute)
2. area to irrigate (acres)
3. irrigation run time the amount of time the system is running in hours
4. irrigation efficiency

#### Results

1. the application rate in inches per hour
2. amount of water applied based on system run time in inches
3. the application rate in millimetres per hour
4. amount of water applied based on system run time in millimetres

one acre = 43,560 square feet
one square foot = 144 square inches
one acre = 43,560 * 144 = 6272640 square inches
one US gallon = 0.133680555555556 cubic foot
one acre/inch of water = 27,154 US gallons
one square foot-inch of water = 0.62 US gallons