Calculator

Category: Irrigation and Water Management

  • Tank Refill Time Calculator


    Tank Refill Time

    L
    L/min

    Estimated time

    — min
    — hours

  • Drip Irrigation Rate Calculator

    Drip Irrigation Rate

    Enter any 4 values and select units
    Efficiency— %
    Flow Rate— m³/s
    — cm³/s
    — L/s
    — mL/s

  • Irrigation Water Requirement Calculator

    What is Irrigation Water Requirement?

    Irrigation Water Requirement (IWR) is the amount of water that must be supplied through irrigation to meet crop water demand after accounting for effective rainfall.

    Formula Used

    IWR (mm) = ETc − Effective Rainfall
    Water Volume (m³) = IWR (mm) × Area (ha) × 10

    Where:
    • ETc = Crop evapotranspiration (mm)
    • Effective rainfall = Useful rainfall (mm)
    • 1 mm water over 1 ha = 10 m³

    Enter Field Data

    Field Notes:
    • ETc = ET0 × Kc
    • Effective rainfall excludes runoff & deep percolation
    • Used in canal scheduling & micro-irrigation design

  • Crop Water Requirement (ETc)

    🌱 Crop Water Requirement (ETc)

    What is Crop Water Requirement?

    Crop Water Requirement (ETc) is the total amount of water needed by a crop for evapotranspiration during its growth period. It depends on climate and crop type.

    Formula Used

    ETc = ET0 × Kc

    Where:
    • ET0 = Reference evapotranspiration (mm)
    • Kc = Crop coefficient (dimensionless)

    Enter Required Data

    Important Notes:
    • Kc varies with crop growth stages
    • ET0 is obtained from weather data or pan evaporation
    • ETc is used for irrigation scheduling

  • Reference Evapotranspiration (ET₀)

    🌾 Reference Evapotranspiration (ET₀)

    What is Reference ET?

    Reference Evapotranspiration (ET₀) represents the rate of evapotranspiration from a hypothetical reference grass crop under standard climatic conditions.

    Method Used (FAO-56)

    This calculator uses the Pan Evaporation Method, most commonly applied in India.

    Formula Used

    ET0 = Kp × Epan

    Where:
    • Epan = Pan evaporation (mm/day)
    • Kp = Pan coefficient (0.6 – 0.85)

    Enter Required Data

    Typical Kp Values:
    • Open field: 0.70–0.75
    • Moderate wind & humidity: 0.65–0.70
    • Sheltered conditions: up to 0.85

  • Consumptive Use of Water (CU)

    What is Consumptive Use?

    Consumptive Use of Water (CU) is the total quantity of water used by a crop through transpiration and evaporation from the soil surface during its entire growing period.

    Standard Agronomy Formula

    CU = ET + ΔS

    Where:
    • ET = Evapotranspiration (mm)
    • ΔS = Change in soil moisture storage (mm)

    Enter Required Data

    Important:
    • CU is expressed in mm of water
    • Used in irrigation scheduling & WUE studies
    • Common in ICAR-NET & ARS numerical problems

  • Net Irrigation Requirement (NIR) Calculator

    What is NIR?

    Net Irrigation Requirement (NIR) is the amount of irrigation water required by a crop to meet its water demand after accounting for effective rainfall and soil moisture contribution.

    Standard Agronomy Formula

    NIR = ETc − (ER + ΔS)

    Where:
    • ETc = Crop water requirement (mm)
    • ER = Effective rainfall (mm)
    • ΔS = Contribution from soil moisture (mm)

    Enter Required Data

    Key Notes:
    • NIR is expressed in mm of water
    • Used to calculate Gross Irrigation Requirement (GIR)
    • Very important for irrigation scheduling & exam numericals

  • Gross Irrigation Requirement (GIR)

    What is GIR?

    Gross Irrigation Requirement (GIR) is the total amount of water that must be applied at the field inlet to satisfy the net irrigation requirement, considering losses due to application inefficiency.

    Standard Agronomy Formula

    GIR = NIR / Ei

    Where:
    • NIR = Net irrigation requirement (mm)
    • Ei = Irrigation efficiency (decimal form)

    Enter Required Data

    Important Notes:
    • Efficiency must be converted into decimal
    • Lower efficiency → higher GIR
    • Used in canal, sprinkler & drip irrigation planning

  • Irrigation Interval Calculator

    What is Irrigation Interval?

    Irrigation Interval is the number of days between two successive irrigations. It depends on the net depth of irrigation and the daily consumptive use of water.

    Standard Agronomy Formula

    Irrigation Interval (days) = Net Depth of Irrigation / Daily ET

    Where:
    • Net Depth of Irrigation = mm of water applied per irrigation
    • Daily ET = Daily crop water use (mm/day)

    Enter Required Data

    Important Notes:
    • Higher ET → shorter irrigation interval
    • Sandy soils → shorter interval
    • Clay soils → longer interval

  • Irrigation Efficiency Calculator

    What is Irrigation Efficiency?

    Irrigation Efficiency indicates how effectively the applied irrigation water is used by the crop. Losses occur due to runoff, deep percolation, and evaporation.

    Standard Formula

    Irrigation Efficiency (%) = (Water stored in root zone / Water applied) × 100

    Where:
    • Water stored = Effective water available to crop (mm)
    • Water applied = Total irrigation water supplied (mm)

    Enter Required Data

    Typical Efficiency Ranges:
    • Surface irrigation: 35–60%
    • Sprinkler irrigation: 60–75%
    • Drip irrigation: 80–95%