Chapter
Apr 26, 2012
ASCE's Standardized Reference Evapotranspiration Equation
Authors: I. A. Walter, M.ASCE, R. G. Allen, M.ASCE, R. Elliott, M.ASCE, M. E. Jensen, M.ASCE, D. Itenfisu, M.ASCE, B. Mecham, M.ASCE, T. A. Howell, M.ASCE, … Show All … , R. Snyder, M.ASCE, P. Brown, M.ASCE, S. Echings, M.ASCE, T. Spofford, M.ASCE, M. Hattendorf, M.ASCE, R. H. Cuenca, M.ASCE, J. L. Wright, M.ASCE, and D. Martin, M.ASCE Show FewerAuthor Affiliations
Publication: Watershed Management and Operations Management 2000
Abstract
The ASCE Evapotranspiration in Irrigation and Hydrology Committee (ASCE-ET) is recommending, for the intended purpose of establishing uniform evapotranspiration (ET) estimates and transferable crop coefficients, two Standardized Reference Evapotranspiration Surfaces: (1) a short crop (similar to grass) and (2) a tall crop (similar to alfalfa), and one Standardized Reference Evapotranspiration Equation. The standardized equation is derived from the ASCE-Penman Monteith equation, by simplifying several terms within that equation. The standardized equation, with appropriate constants provided in an accompanying table, is used to calculate evapotranspiration for the standardized short reference (ETos) and/or evapotranspiration for the standardized tall reference (ETrs). One constant is in the numerator and one is in the denominator. The constant in the right-hand side of the numerator (Cn) is a function of the time step and aerodynamic resistance (i.e., reference type). The constant in the denominator (Cd) is a function of the time step, bulk surface resistance, and aerodynamic resistance (the latter two terms vary with reference to type, time step, and daytime/nighttime).
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© 2000 American Society of Civil Engineering.
History
Published online: Apr 26, 2012
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ASCE Technical Topics:
- Aerodynamics
- Agriculture
- Business management
- Construction engineering
- Construction management
- Continuum mechanics
- Crops
- Design (by type)
- Dynamics (solid mechanics)
- Ecosystems
- Engineering fundamentals
- Engineering mechanics
- Environmental engineering
- Evaporation
- Evapotranspiration
- Hydrologic engineering
- Irrigation
- Irrigation engineering
- Load and resistance factor design
- Load factors
- Organizations
- Practice and Profession
- Professional societies
- Solid mechanics
- Standards and codes
- Structural design
- Vegetation
- Water and water resources
Authors
Affiliations
I. A. Walter, M.ASCE
Task Committee on Standardization of Reference Evapotranspiration and/or the Water Management Committee of the Irrigation Association
R. G. Allen, M.ASCE
Task Committee on Standardization of Reference Evapotranspiration and/or the Water Management Committee of the Irrigation Association
R. Elliott, M.ASCE
Task Committee on Standardization of Reference Evapotranspiration and/or the Water Management Committee of the Irrigation Association
M. E. Jensen, M.ASCE
Task Committee on Standardization of Reference Evapotranspiration and/or the Water Management Committee of the Irrigation Association
D. Itenfisu, M.ASCE
Task Committee on Standardization of Reference Evapotranspiration and/or the Water Management Committee of the Irrigation Association
B. Mecham, M.ASCE
Task Committee on Standardization of Reference Evapotranspiration and/or the Water Management Committee of the Irrigation Association
T. A. Howell, M.ASCE
Task Committee on Standardization of Reference Evapotranspiration and/or the Water Management Committee of the Irrigation Association
R. Snyder, M.ASCE
Task Committee on Standardization of Reference Evapotranspiration and/or the Water Management Committee of the Irrigation Association
P. Brown, M.ASCE
Task Committee on Standardization of Reference Evapotranspiration and/or the Water Management Committee of the Irrigation Association
S. Echings, M.ASCE
Task Committee on Standardization of Reference Evapotranspiration and/or the Water Management Committee of the Irrigation Association
T. Spofford, M.ASCE
Task Committee on Standardization of Reference Evapotranspiration and/or the Water Management Committee of the Irrigation Association
M. Hattendorf, M.ASCE
Task Committee on Standardization of Reference Evapotranspiration and/or the Water Management Committee of the Irrigation Association
R. H. Cuenca, M.ASCE
Task Committee on Standardization of Reference Evapotranspiration and/or the Water Management Committee of the Irrigation Association
J. L. Wright, M.ASCE
Task Committee on Standardization of Reference Evapotranspiration and/or the Water Management Committee of the Irrigation Association
D. Martin, M.ASCE
Task Committee on Standardization of Reference Evapotranspiration and/or the Water Management Committee of the Irrigation Association
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Save for later Item saved, go to cart Information on ASCE Library Cards
ASCE Library Cards let you download journal articles, proceedings papers, and available book chapters across the entire ASCE Library platform. ASCE Library Cards remain active for 24 months or until all downloads are used. Note: This content will be debited as one download at time of checkout.
Terms of Use: ASCE Library Cards are for individual, personal use only. Reselling, republishing, or forwarding the materials to libraries or reading rooms is prohibited.
Terms of Use: ASCE Library Cards are for individual, personal use only. Reselling, republishing, or forwarding the materials to libraries or reading rooms is prohibited.