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Potential Evapotranspiration of Crop is the potential evaporation from soils plus transpiration by plants for medium natural vegetation. It represents the maximum amount of water that would be evaporated and transpired if there were sufficient water available.
The calculator uses the formula:
Where:
Explanation: For medium natural vegetation, the potential evapotranspiration is considered equal to the reference crop evapotranspiration, hence the multiplier of 1.
Details: Accurate evapotranspiration estimation is crucial for irrigation planning, water resource management, agricultural productivity, and hydrological studies. It helps determine crop water requirements and optimize water usage.
Tips: Enter the reference crop evapotranspiration value in meters per second (m/s). The value must be a positive number greater than zero.
Q1: What is Reference Crop Evapotranspiration?
A: Reference Crop Evapotranspiration (ET₀) is a hypothetical grass reference crop with an assumed crop height of 0.12 m, fixed surface resistance of 70 s/m, and albedo of 0.23.
Q2: Why use a multiplier of 1 for medium natural vegetation?
A: For medium natural vegetation, the crop coefficient is typically 1, meaning the evapotranspiration rate is equivalent to the reference crop evapotranspiration.
Q3: What are typical ET values for different crops?
A: ET values vary by crop type, growth stage, and environmental conditions. Most crops have ET values ranging from 0.5 to 1.2 times the reference ET₀.
Q4: How is reference evapotranspiration measured?
A: ET₀ can be measured using lysimeters, calculated from meteorological data using formulas like Penman-Monteith, or estimated from evaporation pans.
Q5: What factors affect evapotranspiration rates?
A: Solar radiation, temperature, humidity, wind speed, crop type, growth stage, and soil moisture content all influence evapotranspiration rates.