1、Second EditionEvaporation, Evapotranspiration, and Irrigation Water RequirementsTask Committee on Revision of Manual 70EdItEd by Marvin E. Jensen, Ph.D., NAERichard G. Allen, Ph.D., P.E.ASCE Manuals and Reports on Engineering Practice No. 70ASCE Manuals and Reports on Engineering Practice No. 70Evap
2、oration,Evapotranspiration,and Irrigation WaterRequirementsSecond EditionPrepared by theTask Committee on Revision of Manual 70Edited byMarvin E. Jensen, Ph.D., NAERichard G. Allen, Ph.D., P.E.Sponsored by theCommittee on Evapotranspiration in Irrigationand Hydrology of the Irrigation and Drainage C
3、ouncil of theEnvironmental and Water Resources Institute of theAmerican Society of Civil EngineersPublished by the American Society of Civil EngineersLibrary of Congress Cataloging-in-Publication DataNames: Jensen, Marvin Eli, 1926- editor. | Allen, R. G. (Rick G.), editor. | American Society of Civ
4、ilEngineers. Task Committee on Revision of Manual 70. | Environmental and Water ResourcesInstitute (U.S.). Committee on Evapotranspiration in Irrigation and HydrologyTitle: Evaporation, evapotranspiration, and irrigation water requirements/prepared by the TaskCommittee on Revision of Manual 70 ; edi
5、ted by Marvin E. Jensen, Ph.D., NAE, Richard G. Allen,Ph.D.,P.E.;sponsoredbytheCommitteeonEvapotranspirationinIrrigationandHydrologyoftheIrrigation and Drainage Council of the Environmental and Water Resources Institute of theAmerican Society of Civil Engineers.Other titles: Evapotranspiration and i
6、rrigation water requirements.Description: Secondedition. |Reston, Virginia:AmericanSociety ofCivil Engineers,2016 |Series:ASCEmanualsandreportsonengineeringpractice;No.70|Includesbibliographicalreferencesand index.Identiers: LCCN 2015011931| ISBN 9780784414057 (print : alk. paper) | ISBN 97807844792
7、09(ebook)Subjects: LCSH: EvapotranspirationHandbooks, manuals, etc. | CropsWater requirementsHandbooks, manuals, etc. | Irrigation waterHandbooks, manuals, etc. | Irrigation farmingHandbooks, manuals, etc.Classication: LCC S600.7.E93 E93 2016 | DDC 631.5/87dc23 LC record available at http:/lccn.loc.
8、gov/20150119312015011931Published by American Society of Civil Engineers1801 Alexander Bell DriveReston, Virginia, 20191-4382www.asce.org/bookstore | ascelibrary.orgAnystatementsexpressedinthesematerialsarethoseoftheindividualauthorsanddonotnecessarilyrepresent the views of ASCE, which takes no resp
9、onsibility for any statement made herein. Noreference made in this publication to any specic method, product, process, or service constitutes orimplies an endorsement, recommendation, or warranty thereof by ASCE. The materials are forgeneral information only and do not represent a standard of ASCE,
10、nor are they intended as areference in purchase specications, contracts, regulations, statutes, or any other legal document.ASCE makes no representation or warranty of any kind, whether express or implied, concerning theaccuracy, completeness, suitability, or utility of any information, apparatus, p
11、roduct, or processdiscussed in this publication, and assumes no liability therefor. The information contained in thesematerialsshouldnotbeusedwithoutrstsecuringcompetentadvicewithrespecttoitssuitabilityforany general or specic application. Anyone utilizing such information assumes all liability aris
12、ingfrom such use, including but not limited to infringement of any patent or patents.ASCE and American Society of Civil EngineersRegistered in U.S. Patent and Trademark Ofce.Photocopies and permissions. Permission to photocopy or reproduce material from ASCE publicationscan be requested by sending a
13、n e-mail to permissionsasce.org or by locating a title in ASCEs CivilEngineeringDatabase(http:/cedb.asce.org)orASCELibrary(http:/ascelibrary.org)andusingthe“Permissions” link.Errata: Errata, if any, can be found at http:/dx.doi.org/10.1061/9780784414057.Copyright 2016 by the American Society of Civi
14、l Engineers.All Rights Reserved.ISBN 978-0-7844-1405-7 (print)ISBN 978-0-7844-7920-9 (PDF)Manufactured in the United States of America.2 212019181716 12345 MANUALS AND REPORTS ONENGINEERING PRACTICE(As developed by the ASCE Technical Procedures Committee, July 1930,and revised March 1935, February 1
15、962, and April 1982)A manual or report in this series consists of an orderly presentation offactsonaparticularsubject,supplementedbyananalysisoflimitationsandapplications of these facts. It contains information useful to the averageengineerinhisorhereverydaywork,ratherthanndingsthatmaybeusefulonlyoc
16、casionallyorrarely.Itisnotinanysensea “standard,” however;noris it so elementary or so conclusive as to provide a “rule of thumb” fornonengineers.Furthermore, material in this series, in distinction from a paper (whichexpresses only one persons observations or opinions), is the work of acommittee or
17、 group selected to assemble and express information on aspecictopic.Asoftenaspracticablethecommitteeisunderthedirectionofone or more of the Technical Divisions and Councils, and the productevolved has been subjected to review by the Executive Committee of theDivision or Council. As a step in the pro
18、cess of this review, proposedmanuscripts are often brought before the members of the Technical Divi-sionsandCouncilsforcomment,whichmayserveasthebasisforimprove-ment. When published, each work shows the names of the committees bywhich it was compiled and indicates clearly the several processes throu
19、ghwhichithaspassedinreview,sothatitsmeritmaybedenitelyunderstood.InFebruary1962(andrevisedinApril1982),theBoardofDirectionvotedtoestablishaseriestitled“ManualsandReportsonEngineeringPractice,”toinclude the Manuals published and authorized to date, future Manuals ofProfessionalPractice,andReportsonEn
20、gineeringPractice.AllsuchManualor Report material of the Society would have been refereed in a mannerapproved by the Board Committee on Publications and would be bound,with applicable discussion, in books similar to past Manuals. Numberingwould be consecutive and would be a continuation of present M
21、anualnumbers. In some cases of joint committee reports, bypassing of journalpublications may be authorized.Alistofavailable ManualsofPracticecanbefoundathttp:/www.asce.org/bookstore.This page intentionally left blankTASK COMMITTEE ON REVISION OF MOP 70Task CommitteeMarvin E. Jensen, Editor Consultan
22、t, Fort Collins, Colorado(formerly Director, Colorado Institute forIrrigation Management, and NationalProgram Leader for Water Management,Agricultural Research Service, USDA)Richard G. Allen, Editor Water Resources Engineering Professor,Kimberly Research and Extension Center,University of Idaho, Kim
23、berlyTerry A. Howell Laboratory Director (retired), Conservationand Research Leader, Conservation andProduction Laboratory, AgriculturalResearch Service, USDA, Bushland, TXDerrel L. Martin Professor, Department of BiologicalSystems, Engineering, University ofNebraska, LincolnRichard Snyder Biometeor
24、ologist Specialist, Department ofLand,Air,and WaterResources, Universityof California, DavisIvan A. Walter Principal, Ivans Engineering, Centennial,COBLUE RIBBON REVIEW PANELPaul W. Brown University of Arizona, TucsonRonald L. Elliott UniversityofOklahoma(retired),StillwaterThomas W. Ley formerly wi
25、th Colorado Division of WaterResources, Pueblo, now with NaturalResources Consulting Engineers, FortCollins, COThomas Trout Agricultural Research Service (retired),USDA, Fort Collins, COThis page intentionally left blankDEDICATIONIn loving memory of Doris Jensen, 19292009, lifelongspouse, supporter,
26、 encourager, and travelingcompanion of Marvin Jensen.In fond memory of William Oregon Pruitt, 19222009,Irrigation Engineer at the University of California-Davis, who was a primary leader in developingand advancing the concept of reference crop evapo-transpiration (ET) and transferable crop coefcient
27、s, intrustingtheuseofenergybalanceequationstoestimateET, in advocating data and research quality andintegrity, and in promoting education in experi-mental methods. Bill Pruitt, along with Dr. JamesL. Wright of the USDA-ARS (retired), Kimberly,Idaho, mentored many present-day practitioners on the phy
28、sics of ETestimation and the requirements for accurate ET measurement. Pruittand Wright were both longtime members of and contributors to theASCE Technical Committee on Evapotranspiration in Irrigation andHydrology.viiIn fond memory of John Lennox Monteith, 19292012,who inuenced many Americans in th
29、e application ofphysicalprinciplestodescribehowplants interact withtheir immediate environment and microclimate, withhis own work leading to the evolution of the Penmancombination equation into the Penman-Monteithequation, which has become a primary basis forestimating irrigation water requirements.
30、viii DEDICATIONCONTENTSPREFACE.xiiiACKNOWLEDGMENTS.xvNOTATION.xviiPART 1: BASIC CONCEPTS 11. INTRODUCTION AND HISTORY. 31.1 Introduction to Second Edition31.2 Development of ET and CU Studies in the United States.71.3 Revised Edition.162. EVAPORATION AND EVAPOTRANSPIRATIONPROCESSES 192.1 Introductio
31、n 192.2 The Water Budget202.3 The Energy Budget 212.4 Controlling Factors.212.5 Estimating Concepts272.6 Measurement Methods293. SOIL-PLANT-ATMOSPHERE SYSTEM. 353.1 Introduction 353.2 Physical Properties of Water, Water Vapor, and Air .353.3 Soil Properties.443.4 Soil-Water System443.5 Vegetative (C
32、rop) Properties544. ENERGY BALANCE 594.1 Introduction 594.2 Energy Balance.59ix4.3 Net Radiation614.4 Soil Heat Flux Density.805. SURFACE-ENERGY AND AIR-MASS INTERACTIONSAND THE CONCEPT OF REFERENCE ET. 875.1 Introduction 875.2 Weather and Surface Effects on Conversionof Energy to Latent Heat Flux90
33、5.3 Standardization of the Vegetative Cover .936. EVAPORATION FROM WATER SURFACES 996.1 Introduction 996.2 Methods of Estimating Water Surface Evaporation .1006.3 Example Applications of Evaporation EstimationMethods and Measurements1266.4 Summary of Methods for Estimating Evaporationfrom Water Bodi
34、es.135PART 2: EVAPOTRANSPIRATION FROM LAND SURFACES. 1397. WATER AND ENERGY BALANCE COMPONENTSFOR MEASUREMENT AND ESTIMATION 1417.1 Introduction to Chapters 7121417.2 Volumetric Measurements for Estimating LandSurface ET1427.3 Mass Balance Methods1497.4 Energy Balance MethodsBowen Ratio1627.5 Mass T
35、ransfer Method Using Eddy Covariance.1687.6 Fetch Requirements for Boundary Layer Measurement1727.7 Advantages and Disadvantages of ET MeasurementMethods.1757.8 Combined Energy Balance and Mass Transfer Methods.1768. REFERENCE CROP ET. 1898.1 Introduction 1898.2 The Penman-Monteith Equation1908.3 Ae
36、rodynamic and Surface Parameters for thePM Equation.1928.4 Reference ETrefKcApproach 1958.5 Missing or Bad Weather Data2068.6 Reference ET by Analogy or Association.2149. EVAPORATION FROM SOIL 2219.1 Introduction 2219.2 The Evaporation Process.2219.3 Diurnal Effects and Redistribution of Soil Water2
37、229.4 Stage 1 Evaporation.223x CONTENTS9.5 Stage 2 Evaporation.2259.6 Evaporation Models.2279.7 Relationships between Evaporation and Transpiration.2409.8 Water Balance of the Evaporation Layer2439.9 Example Estimates of Evaporation2459.10 Summary.25810. CROP COEFFICIENT METHOD. 26110.1 Introduction
38、 26110.2 The Crop Coefcient26110.3 Crop (Vegetation Cover) Coefcients.26510.4 FAO Grass-Based Crop Coefcients .27310.5 Alfalfa-Based Crop Coefcients.28510.6 Estimates of KcCurves for Natural andAgricultural Vegetation.28710.7 Landscape Coefcients29410.8 Estimates of Kcduring Wintertime andNongrowing
39、 Seasons.31310.9 Summary.32111. DIRECT PENMAN-MONTEITH AND AERODYNAMICENERGY BALANCE EQUATIONS. 32311.1 Introduction 32311.2 Common Forms of Resistance-Based Equations.32511.3 Challenges with Types of Resistance-Based Models34011.4 Parameters for the Penman-Monteith for Equivalencywith More Complica
40、ted Models34211.5 Comparative Model Performance34311.6 Roughness Length and Zero Plane Displacement34511.7 Bulk Surface (Stomatal) Resistance35511.8 Evaporation from Soil and Surface Resistance37911.9 Weather Measurements for Direct Application of thePenman-Monteith and AFIB Methods and ReferenceET
41、Calculation38711.10 Example Applications of the Single-LayerPenman-Monteith.39611.11 Applications of Evapotranspiration ModelsUsing Remote Sensing Inputs40811.12 Measurement and Estimation of ET onSloping Lands.40911.13 Evaporation of Intercepted Rainfall41012. REGIONAL ESTIMATES OF EVAPOTRANSPIRATI
42、ON. 41512.1 Introduction 41512.2 Theory41612.3 Applications418CONTENTS xiPART 3: WATER REQUIREMENT ESTIMATES 42513. SELECTION OF APPROPRIATE ESTIMATING METHOD. 42713.1 Introduction 42713.2 Time Frame and Required Accuracy 42713.3 Input Data Collection, Screening, and Processing42813.4 Crop Coefcient
43、 Method vs. Direct Methods43013.5 Evaporation and Evapotranspiration Calculations.43113.6 Summary.43314. ESTIMATES OF IRRIGATION WATER REQUIREMENTSAND STREAMFLOW DEPLETION 43514.1 Introduction 43514.2 Net Irrigation Water Requirement and EffectivePrecipitation43514.3 Leaching Requirement.43914.4 Mis
44、cellaneous Water Requirements44314.5 System Losses.44514.6 Precipitation Runoff.45114.7 Improvements in Estimating Water Requirements.45414.8 Depletions to the Water Resource.455APPENDIXESA. Conversion and Meteorological Tables457B. Mean Crop Coefcients in Subhumid Climates.471C. Lengths of Crop Dev
45、elopment Stages487D. Basal Crop Coefcients in Subhumid Climates499E. Mean and Basal Crop Coefcients for CropsCommon to Temperate and Continental Climates.513F. Basal Crop Coefcients for Crops Common toTemperate and Continental Climates with Thermal Basis523G. Documentation for Crop Coefcient and ET
46、DataReporting and Determination of ET from Remote Sensing543H. Weather Data Integrity.569I. Contribution of Capillary Flow from a ShallowWater Table to Evaporation and Evapotranspiration609J. Derivation of the Penman-Monteith Equation619K. Regional Estimating Methods and MethodsNot Commonly Used in
47、the United States627L. Comparison and Ranking of Methods for Estimating ET.637M. Glossary 661REFERENCES 669INDEX. 733xii CONTENTSPREFACEThisManualofPracticeprovidesinformationonevaporationandevapo-transpiration that practicing engineers, hydrologists, and others need toevaluate data received from va
48、rious sources. It also provides backgroundinformation to enable practicing engineers, educators, and researchers toimprove procedures for estimating evapotranspiration (ET) to achieve theaccuracy needed for specic purposes.This manual updates and expands the scope of the rst edition, Evapo-transpira
49、tion and Irrigation Water Requirements, published in 1990. The man-ualisintendedforusebyconsultingengineersworkingonwaterissuesandinstructors in agricultural and civil engineering, environmental sciences,andagronomy.Itisintendedtoserveasaprimaryreferenceforagricultural,environmental, and engineering students, and professionals in water-relat-edagencies.Thisrevisededitionincorporatesmanyyearsofuserexperiencewiththepreviousmanualandrecentadvancesinthephysicsofevaporati
