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Crop water requirements

Year of publication 1992

Author Doorenbos, J.; Pruitt, W.O.; Aboukhaled, A.; Damagnez, J.; Dastane, N.G.; Van den Berg, C.; Rijtema, P.E.; Ashford, O.M.; Frere, M;Land and Water Division

Product type Book (stand-alone)

Series title FAO Irrigation and Drainage Paper

Series number 0254-5284

Edition 1

Synopsis (short abstract) This publication is intended to provide guidance in determining crop water requirements and their application in planning, design and operation of irrigation projects. Part 1.1 presents suggested methods to derive crop water requirements. The use of four well-known methods for determining such requirements is defined to obtain reference crop evapotranspiration (ETo), which denotes the level of evapotranspiration for different climatic conditions. These methods are the Bla.ney- Criddl e, the Radiation, the Penman and Pan Evaporation methods, each requiring a different set of climatic data. To derive the evapotranspiration for a specific crop, relationships between crop evapotran.spiration (ETcrop) and reference crop evapotranspiration (ETo) are given in Part I . 2 for different crops , stages of growth, length of growing season and prevailing climatic conditions. The effect of local conditions on crop water requirements is given in Part 1.3; this includes local va riation in climate, advection, soil water availability and agronomic and irrigation methods and practices . Calculation procedures are presented together with examples. A detailed discussion on selection and calibration of the preSented methodologies together with the data sources is given in Appendix II. A computer programme on applying the different methods is given in Appendix III. Part 11 discusses the application of crop water requirements data in irrigationproject planning, des ign and operation.. Part II. 1 deals v.rith deriving the field water balance, which in turn forms the basis for predicting season.al and peak irrigation supplies for general planning purposes. Attention is given to irrigation efficiency and water requirements for cultural practices and leaching of salts. In Part 11.2 methods are presented to arrive at field and scheme supply schedules with emphasis towards the field water balance and field irrigation management. Criteria are given fo r operating the canal system using different methods of water delivery, and for subsequent design parameters of the system. Suggestions are made in Part 11.3 on refinement of field and project supply schedules once the project is in operation. The presented guidelines are based on measured data and experience obtained covering a wide range of conditions. Local practical, technical, social a.nd economic considerations will, however, affect the planning criteria selected. Therefore c aution and a critical attitude should still be taken when applyin.g the presented methodology.

Language English

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    Book (stand-alone)
    Guidelines for predicting crop water requirements 1977
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    This publication is intended to provide guidance in determining crop water requirements and their application in planning, design and operation of irrigation projects. Part 1.1 presents suggested methods to derive crop water requirements. The use of four well-known methods for determining such requirements is defined to obtain reference crop evapotranspiration (ETo), which denotes the level of evapotranspiration for different climatic conditions. These methods are the Bla.ney- Criddle, t he Radiation, the Penman and Pan Evaporation methods, each requiring a different set of climatic data. To derive the evapotranspiration for a specific crop, relationships between crop evapotran.spiration (ETcrop) and reference crop evapotranspiration (ETo) are given in Part I . 2 for different crops , stages of growth, length of growing season and prevailing climatic conditions. The effect of local conditions on crop water requirements is given in Part 1.3; this includes local variat ion in climate, advection, soil water availability and agronomic and irrigation methods and practices . Calculation procedures are presented together with examples. A detailed discussion on selection and calibration of the preSented methodologies together with the data sources is given in Appendix II. A computer programme on applying the different methods is given in Appendix III. Part 11 discusses the application of crop water requirements data in irrigationproject planning, design and operation.. Part II. 1 deals v.rith deriving the field water balance, which in turn forms the basis for predicting season.al and peak irrigation supplies for general planning purposes. Attention is given to irrigation efficiency and water requirements for cultural practices and leaching of salts. In Part 11.2 methods are presented to arrive at field and scheme supply schedules with emphasis towards the field water balance and field irrigation management. Criteria are given for op erating the canal system using different methods of water delivery, and for subsequent design parameters of the system. Suggestions are made in Part 11.3 on refinement of field and project supply schedules once the project is in operation. The presented guidelines are based on measured data and experience obtained covering a wide range of conditions. Local practical, technical, social a.nd economic considerations will, however, affect the planning criteria selected. Therefore cauti on and a critical attitude should still be taken when applyin.g the presented methodology.
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    Irrigation scheduling: From theory to practice. Proceedings 1996
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    Meeting
    Report on the Expert Consultation on Procedures for Revision of FAO Guidelines for Prediction of Crop Water Requirements
    Rome, Italy, 28-31 May 1990
    1990
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    In this series of publications, the FAQ methodology for the prediction of crop water requirements has been quite an outstanding example. The PAO-No. 24, as it has become known, has become an international standard, extensively used worldwide by irrigation engineers, agronomists, hydrologists and environmentalists. More than 20 000 copies of the publication have·been distributed in four languages. The methodology is commonly applied in many studies and development proposals, and endorsed by the major financing and development agencies as the recommended method. In many educational institutes and universities, the F AO methodology is part of the curriculum. To improve on the methodologies the collaboration of a wide range of resource people and institutions worldwide needed to be assured in order to establish accepted procedures to review the methodologies and update procedures for estimation of crop water requirements. Collaboration was established with the International Commission for Irrigation and Drainage, the American Societies for Civil and Agricultural Engineers and the World Meteorological Organization. To establish the wide forum required, F AO organized a consultation of eminent experts and researchers which was held from 28 to 31 May 1990 in Rome, Italy, to advise on procedures for review. Results on the outcome of the meeting incorporating the specific suggestions and recommendations are included in this report.
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