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Hargreave's Class A Pan Evaporation Method Formula:
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Hargreave's Class A Pan Evaporation Method is a technique used to estimate evapotranspiration by measuring the evaporation from a standard pan and applying a crop-specific factor. It provides a practical approach for agricultural water management and irrigation planning.
The calculator uses the Hargreave's formula:
Where:
Explanation: The equation calculates evapotranspiration by multiplying the pan evaporation measurement by a crop-specific factor that accounts for differences in water requirements between the standard pan and actual crops.
Details: Accurate evapotranspiration estimation is crucial for efficient irrigation scheduling, water resource management, and agricultural planning. It helps determine the appropriate amount of water needed for crops to optimize growth and conserve water resources.
Tips: Enter the crop factor (typically ranging from 0.1 to 1.2 depending on crop type and growth stage) and pan evaporation measurement in centimeters. Both values must be positive numbers greater than zero.
Q1: What Is A Standard Class A Evaporation Pan?
A: A standard Class A evaporation pan is a cylindrical container with specific dimensions (121cm diameter, 25.5cm depth) used to measure evaporation rates under standardized conditions.
Q2: How Do Crop Factors Vary?
A: Crop factors vary based on crop type, growth stage, climate conditions, and agricultural practices. They typically range from 0.1 for dormant crops to 1.2 for crops with high water demand.
Q3: When Should Pan Evaporation Be Measured?
A: Pan evaporation should be measured daily, preferably in the morning, and the pan should be maintained with proper water levels and protection from debris and animals.
Q4: Are There Limitations To This Method?
A: This method may be less accurate in extreme weather conditions, for certain crop types, or in areas with significant microclimate variations compared to the pan location.
Q5: How Often Should Calculations Be Performed?
A: Calculations should typically be performed daily during the growing season to support effective irrigation scheduling and water management decisions.