Hydrology & Water Resources Engineering - Vol 2 | 19. Evapotranspiration by Abraham | Learn Smarter
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19. Evapotranspiration

19. Evapotranspiration

Evapotranspiration (ET) is a crucial component of the hydrologic cycle, integrating both evaporation and transpiration processes, influencing water demand and resource management. Understanding ET is essential for effective agricultural practices, particularly in regions with limited water resources, as it depends on various climatic, crop, and soil factors. The chapter explores methods for estimating ET, measurement techniques, and the impacts of climate change on ET dynamics.

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  1. 19
    Evapotranspiration

    Evapotranspiration (ET) combines evaporation and transpiration processes,...

  2. 19.1
    Evapotranspiration – Definition And Concept

    Evapotranspiration (ET) comprises the combined processes of evaporation and...

  3. 19.2
    Components Of Evapotranspiration

    Evapotranspiration consists of two main components: evaporation and...

  4. 19.2.1
    Evaporation (E)

    Evaporation is a key component of evapotranspiration that refers to the...

  5. 19.2.2
    Transpiration (T)

    Transpiration is a key process in the evapotranspiration cycle where plants...

  6. 19.3
    Factors Affecting Evapotranspiration

    Evapotranspiration is influenced by various climatic, crop, soil, and...

  7. 19.4
    Potential And Actual Evapotranspiration

    This section defines Potential Evapotranspiration (PET) and Actual...

  8. 19.5
    Methods Of Estimating Evapotranspiration

    Various methods are employed to estimate evapotranspiration (ET), classified...

  9. 19.5.1
    Empirical Methods

    Empirical methods are used to estimate evapotranspiration (ET) through the...

  10. 19.5.1.1
    Blaney-Criddle Method

    The Blaney-Criddle Method is an empirical approach to estimate potential...

  11. 19.5.1.2
    Hargreaves Method

    The Hargreaves Method is a straightforward temperature-based approach for...

  12. 19.5.1.3
    Pan Evaporation Method

    The Pan Evaporation Method estimates evapotranspiration based on...

  13. 19.5.2
    Energy Balance Methods

    Energy Balance Methods for estimating evapotranspiration involve the...

  14. 19.5.2.1
    Energy Budget Equation

    The Energy Budget Equation details the relationship between net radiation...

  15. 19.5.3
    Combination Methods

    Combination methods for estimating evapotranspiration integrate various...

  16. 19.5.3.1
    Penman Method

    The Penman Method combines energy balance and aerodynamic approaches to...

  17. 19.5.3.2
    Fao Penman-Monteith Method

    The FAO Penman-Monteith Method provides a standardized approach for...

  18. 19.6
    Measurement Techniques For Et

    This section discusses various measurement techniques for evapotranspiration...

  19. 19.6.1

    A lysimeter is a crucial device used for accurately measuring...

  20. 19.6.2
    Atmometer (Evaporimeter)

    The atmometer, or evaporimeter, is an instrument used to measure the rate of...

  21. 19.6.3
    Eddy Covariance System

    The Eddy Covariance System is an advanced method for measuring...

  22. 19.6.4
    Bowen Ratio Energy Balance Method

    The Bowen Ratio Energy Balance Method is a technique used to measure...

  23. 19.6.5
    Remote Sensing Techniques

    Remote sensing techniques utilize satellite data to estimate...

  24. 19.7
    Crop Coefficient (Kc) Concept

    The Crop Coefficient (Kc) is a vital parameter used to calculate the...

  25. 19.8
    Applications Of Evapotranspiration Data

    Evapotranspiration data is crucial for various applications related to water...

  26. 19.9
    Evapotranspiration Under Changing Climate

    This section discusses how climate change impacts evapotranspiration (ET)...

What we have learnt

  • Evapotranspiration is the total water loss from a vegetated surface due to evaporation and transpiration.
  • Factors influencing evapotranspiration include climatic conditions, crop characteristics, soil properties, and management practices.
  • Potential ET represents maximum losses under optimal conditions, while actual ET reflects the effects of varying moisture availability.

Key Concepts

-- Evapotranspiration
The total water loss from soil and vegetation due to the processes of evaporation and transpiration.
-- Potential Evapotranspiration (PET)
The maximum possible evaporation from a given area assuming optimal moisture conditions.
-- Actual Evapotranspiration (AET)
The actual measurement of evaporation that occurs under the prevailing conditions, usually less than PET.
-- Crop Coefficient (Kc)
A factor used to estimate ET of different crops based on crop type and growth stage.
-- Measurement Techniques
Methods to quantify ET, including lysimeters, atmometers, eddy covariance systems, and remote sensing.

Additional Learning Materials

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