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Irrigation Water & Energy Calculator

Irrigation Water & Energy Calculator

Calculate irrigation water requirements, energy consumption, and cost based on crop needs and environmental conditions

Input Parameters
Average daily reference evapotranspiration
Expected rainfall during the irrigation period
%
$
About Irrigation Water & Energy Calculator
What is this calculator for?

This calculator helps farmers determine the amount of water needed for irrigation based on crop stage, soil type, and environmental conditions. It also estimates energy consumption and costs associated with pumping the water—empowering better resource planning.

Key Formulas Used

1. ET Requirement (mm):
ET = Reference ET × Kc × Days Between Irrigation

2. Effective Rainfall (mm):
Effective Rainfall = min(Rainfall × 0.7, ET)

3. Irrigation Required (mm):
Irrigation = ET − Effective Rainfall

4. Adjusted Irrigation:
Adjusted = Irrigation / (Efficiency / 100)

5. Water Volume (m³):
Volume = Adjusted × Field Area (in m²) / 1000

6. Energy Consumption:
Energy = Volume × 0.4 (kWh)

7. Pump Hours =
Energy / Pump Power

8. Energy Cost =
Energy × Cost per kWh

Example Calculation
  • Field size: 2 hectares
  • Reference ET: 5 mm/day
  • Crop stage: Mid-season (Kc = 1.15)
  • Days Between Irrigation: 5
  • Rainfall: 8 mm
  • Efficiency: 70%
  • Pump Power: 5 kW
  • Energy Cost: $0.20 per kWh

ET = 5 × 1.15 × 5 = 28.75 mm
Effective Rainfall = min(8 × 0.7, 28.75) = 5.6 mm
Irrigation Required = 28.75 − 5.6 = 23.15 mm
Adjusted = 23.15 / 0.7 = 33.07 mm
Volume = (33.07 / 1000) × (2 × 10,000) = 661.4 m³
Energy = 661.4 × 0.4 = 264.56 kWh
Pump Hours = 264.56 / 5 = 52.91 hrs
Cost = 264.56 × 0.20 = $52.91

Practical Applications
  • Plan irrigation schedules more efficiently
  • Reduce over-irrigation and water wastage
  • Estimate seasonal water and electricity costs
  • Budget energy needs for pump use
  • Conserve resources during droughts
How to Use This Calculator
Step-by-Step Guide
  1. Select your crop type
  2. Choose the growth stage
  3. Enter your field size and unit
  4. Choose your soil type
  5. Input daily ET (evapotranspiration)
  6. Specify days between irrigation
  7. Input expected rainfall (optional)
  8. Set your irrigation efficiency
  9. Enter your pump power (kW)
  10. Set energy cost ($/kWh)
  11. Click Calculate to view results
Tips for Accurate Results
  • Use accurate ET values from weather stations
  • Adjust Kc values based on crop type and location
  • Don’t forget to include rainfall—only 70% is usable
  • Efficiency values: drip (90%), sprinkler (75%), furrow (60%)
  • Check pump specs for actual power rating
Pro Tip: Regularly monitor your soil moisture and local ET values to make smarter irrigation decisions.
Frequently Asked Questions

Reference ET is the estimated water loss from soil and crop due to evaporation and transpiration. It's influenced by temperature, wind, humidity, and solar radiation.

Each crop growth stage has a different water demand. Mid-season crops require the most water, while initial and late-season stages require less.

Irrigation efficiency adjusts for water losses during delivery and application. It ensures you provide enough water to meet plant needs without wastage.

Estimates depend on actual pump performance, depth of water table, and local energy tariffs. Adjust the calculator values to match your real system for better accuracy.

Weekly recalculations during peak growing seasons are ideal. Also re-calculate after major weather changes or if crop stages shift.