HDS-2 - Highway Hydrology - Second Edition

Publication No. FHWA-NHI-02-001October 2002U.S. Department of TransportationFederal HighwayAdministrationHydraulic Design Series No. 2, Second EditionHighway HydrologyNational Highway Institute

Technical Report Documentation Page1. Report No.2. Government Accession No.3. Recipient's Catalog No.FHWA-NHI-02-001HDS-24. Title and Subtitle5. Report DateHighway HydrologyHydraulic Design Series Number 2, Second EditionOctober 20026. Performing Organization Code7. Author(s)8. Performing Organization Report No.Richard H. McCuen, Peggy A. Johnson, Robert M. Ragan9. Performing Organization Name and Address10. Work Unit No. (TRAIS)Greenhorne and O’Mara, Inc9001 Edmonston RoadGreenbelt, Maryland 2077011. Contract or Grant No.12. Sponsoring Agency Name and Address13. Type of Report and Period CoveredDTFH61-95-C-00080Federal Highway AdministrationNational Highway Institute4600 North Fairfax DriveSuite 800Arlington, Virginia 22203Final ReportOffice of Bridge Technology400 Seventh StreetRoom 3202Washington D.C. 205901st Edition: Oct 1992 – Jun 19962nd Edition – Nov 2000 – Nov 200114. Sponsoring Agency Code15. Supplementary NotesProject Manager: Joe Krolak – FHWA Eastern Resource CenterTechnical Editor, second edition: Roger T. KilgoreTechnical Assistance, second edition: Dan Ghere, Paul Koch, Imtiaz Shah, Sung-Hee Kim16. AbstractThis document discusses the physical processes of the hydrologic cycle that are important to highwayengineers. These processes include the approaches, methods and assumptions applied in design andanalysis of highway drainage structures.Hydrologic methods of primary interest are frequency analysis for analyzing rainfall and ungaged data;empirical methods for peak discharge estimation; and hydrograph analysis and synthesis. Thedocument describes the concept and several approaches for determining time of concentration. Thepeak discharge methods discussed include log Pearson type III, regression equations, the SCSgraphical method (curve number method), and rational method. The technical discussion of each peakflow approach also includes urban development applications. The document presents common storageand channel routing techniques related to highway drainage hydrologic analyses. The documentdescribes methods used in the planning and design of stormwater management facilities. Specialtopics in hydrology include discussions of arid lands hydrology, wetlands hydrology, snowmelthydrology, and hydrologic modeling, including geographic information system approaches andapplications.This edition includes new sections on wetlands hydrology and snowmelt hydrology, an expandedsection on arid lands hydrology, corrections of minor errors, and inclusion of dual units.17. Key Word18. Distribution StatementHydrology, frequency analysis, peak dischargeestimation, urban hydrology, hydrographdevelopment, storage and channel routing,stormwater management, arid lands hydrology,wetland hydrology, snowmelt hydrology, GISThis document is available to the public from theNational technical Information Service, Springfield,Virginia, 2215119. Security Classif. (of this report)UnclassifiedForm DOT F 1700.7 (8-72)20. Security Classif. (of this page)UnclassifiedReproduction of completed page authorize21. No. of Pages42422. Price

ACKNOWLEDGMENTSFirst EditionThe first edition is a revision of Hydraulic Engineering Circular No. 19, which was written by Mr.Frank D. Masch. This revision uses portions of the contents of HEC-19 for which we recognizeand appreciate the important contributions of Mr. Masch.Mr. Thomas Krylowski served as the FHWA COTR. Mr. Philip Thompson, Ms. Abbi Ginsberg,and Mr. Arlo Waddoups contributed technical assistance. Dr. Gary A. Lewis, Mr. Wilbert O.Thomas, Jr. (U.S. Geological Survey), and Mr. Lawrence J. Harrison reviewed the draftdocuments. Ms. Alison R. Montgomery and Ms. Florence Kemerer drafted figures. Ms. FlorenceKemerer typed and formatted the text.Second EditionThis second edition of this document primarily sought to provide calculations in both metric (SI)and conventional English units and add new material on wetlands and snow melt hydrology.Changes in content and format have been introduced where these appeared to be beneficial toreaders. Mr. Larry Jones was the FHWA COTR for the second edition. Mr. Philip Thompson ofFHWA provided appreciated support and guidance in the preparation of this second edition.We wish to acknowledge the following individuals at Greenhorne & O'Mara, Inc. for theircontributions in the production of this second edition: Ms. Patricia Padgett-Neal, for wordprocessing, Ms. Julie Liptak, for graphic design, and Ms. Deb Daly, for editorial review. GaryLewis and Bruce Curtis, of Parsons, Inc., provided significant contributions to the new specialtopics chapter. Thank you very much!-i-

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TABLE OF CONTENTSPageACKNOWLEDGMENTS . iTABLE OF CONTENTS.iiiLIST OF TABLES.ixLIST OF FIGURES .xiiGLOSSARY .xvCHAPTER 1 INTRODUCTION . 1-11.1HYDROLOGIC CYCLE . 1-11.2HYDROLOGY OF HIGHWAY STREAM CROSSINGS. 1-31.2.1Elements of the Hydrologic Cycle Pertinent to Stream Crossings. 1-31.2.2Overview of Hydrology as Applied to Stream Crossings . 1-31.2.3Channelization . 1-51.2.4Detention Storage. 1-61.2.5Diversions and Dam Construction . 1-61.2.6Natural Disasters . 1-61.3GENERAL DATA REQUIREMENTS. 1-71.4SOLUTION METHODS . 1-71.4.1Deterministic Methods . 1-71.4.2Statistical Methods. 1-71.5ANALYSIS VERSUS SYNTHESIS . 1-81.5.1A Conceptual Representation of Analysis and Synthesis. 1-81.5.2Examples of Analysis and Synthesis in Hydrologic Design . 1-9CHAPTER 2 RAINFALL/RUNOFF PROCESSES . 2-12.1PRECIPITATION. 2-12.1.1Forms of Precipitation. 2-12.1.2Types of Precipitation (by Origin) . 2-12.1.2.1Convective Storms. 2-22.1.2.2Orographic Storms. 2-22.1.2.3Cyclonic Storms . 2-22.1.2.4Hurricanes and Typhoons. 2-32.1.3Characteristics of Rainfall Events . 2-32.1.4Intensity-Duration-Frequency Curves . 2-92.2HYDROLOGIC ABSTRACTIONS . 2-102.2.1Evaporation. 2-102.2.2Transpiration. 2-102.2.3Interception . 2-102.2.4Infiltration . 2-112.2.5Depression Storage . 2-112.2.6Detention Storage. 2-112.2.7Total Abstraction Methods . 2-112.3CHARACTERISTICS OF RUNOFF . 2-112.3.1Peak Discharge . 2-122.3.2Time Variation (Hydrograph) . 2-122.3.3Stage-Discharge . 2-122.3.4Total Volume. 2-132.3.5Frequency. 2-142.3.6Return Period. 2-14-iii-

2.42.52.6EFFECTS OF BASIN CHARACTERISTICS ON RUNOFF. 2-142.4.1Drainage Area. 2-142.4.2Slope. 2-142.4.3Hydraulic Roughness. 2-152.4.4Storage . 2-152.4.5Drainage Density . 2-172.4.6Channel Length . 2-172.4.7Antecedent Moisture Conditions. 2-182.4.8Urbanization. 2-182.4.9Other Factors. 2-18ILLUSTRATION OF THE RUNOFF PROCESS. 2-182.5.1Rainfall Input. 2-192.5.2Interception . 2-192.5.3Depression Storage . 2-192.5.4Infiltration . 2-202.5.5Rainfall Excess . 2-202.5.6Detention Storage. 2-202.5.7Local Runoff. 2-202.5.8Outflow Hydrograph. 2-20TRAVEL TIME. 2-212.6.1Time of Concentration . 2-212.6.2Velocity Method . 2-212.6.2.1Sheet-Flow Travel Time. 2-222.6.2.2Shallow Concentrated Flow . 2-242.6.2.3Pipe and Channel Flow. 2-24CHAPTER 3 HYDROLOGIC DATA . 3-13.1COLLECTION AND COMPILATION OF DATA . 3-13.1.1Site Investigations and Field Surveys. 3-23.1.2Sources of Other Data . 3-23.1.2.1Stream Flow Data . 3-33.1.2.2Precipitation Data. 3-33.1.2.3Soil Type Data . 3-43.1.2.4Land-Use Data. 3-43.1.2.5Miscellaneous Basic Data. 3-43.2ADEQUACY OF DATA . 3-53.3PRESENTATION OF DATA AND ANALYSIS. 3-5CHAPTER 4 PEAK FLOW FOR GAGED SITES . 4-14.1RECORD LENGTH REQUIREMENTS . 4-14.2STATISTICAL CHARACTER OF FLOODS . 4-24.2.1Analysis of Annual and Partial-Duration Series . 4-24.2.2Detection of Nonhomogeneity in the Annual Flood Series . 4-64.2.3Arrangement by Geographic Location . 4-104.2.4Probability Concepts. 4-114.2.5Return Period. 4-124.2.6Estimation of Parameters . 4-124.2.7Frequency Analysis Concepts . 4-134.2.7.1Frequency Histograms. 4-134.2.7.2Central Tendency. 4-154.2.7.3Variability . 4-17-iv-

4.34.44.54.64.2.7.4Skew . 4-174.2.7.5Generalized and Weighted Skew. 4-204.2.8Probability Distribution Functions . 4-224.2.9Plotting Position Formulas . 4-24STANDARD FREQUENCY DISTRIBUTIONS . 4-254.3.1Normal Distribution . 4-264.3.1.1Standard Normal Distribution. 4-274.3.1.2Frequency Analysis for a Normal Distribution. 4-284.3.1.3Plotting Sample Data . 4-284.3.1.4Estimation with the Frequency Curve . 4-294.3.2Log-Normal Distribution . 4-344.3.2.1Procedure . 4-354.3.2.2Estimation . 4-354.3.3Gumbel Extreme Value Distribution. 4-394.3.4Log-Pearson Type III Distribution . 4-424.3.4.1Procedure . 4-434.3.4.2Estimation . 4-444.3.5Evaluation of Flood Frequency Predictions . 4-524.3.5.1Standard Error of Estimate . 4-544.3.5.2Confidence Limits . 4-554.3.6Other Considerations in Frequency Analysis. 4-594.3.6.1Outliers. 4-594.3.6.2Historical Data. 4-614.3.6.3Incomplete Records and Zero Flows . 4-634.3.6.4Mixed Populations. 4-644.3.6.5Two-Station Comparison . 4-644.3.7Sequence of Flood Frequency Calculations . 4-694.3.8Other Methods for Estimating Flood Frequency Curves. 4-734.3.9Low-flow Frequency Analysis . 4-73INDEX ADJUSTMENT OF FLOOD RECORDS. 4-754.4.1Index Adjustment Method for Urbanization. 4-754.4.2Adjustment Procedure . 4-76PEAK FLOW TRANSPOSITION . 4-85RISK ASSESSMENT . 4-864.6.1Binomial Distribution . 4-874.6.2Flood Risk. 4-89CHAPTER 5 PEAK FLOW FOR UNGAGED SITES. 5-15.1REGIONAL REGRESSION EQUATIONS. 5-15.1.1Analysis Procedure. 5-15.1.2USGS Regression Equations . 5-35.1.2.1Hydrologic Flood Regions. 5-35.1.2.2Assessing Prediction Accuracy. 5-55.1.2.3Comparison with Gaged Estimates. 5-65.1.2.4Application and Limitations . 5-85.1.3USGS Urban Watershed Studies . 5-95.1.3.1Peak Discharge Equations. 5-105.1.3.2Basin Development Factor. 5-105.1.3.3Effects of Future Urbanization . 5-155.1.3.4Local Urban Equations. 5-16-v-

5.25.35.45.55.1.4National Flood Frequency Program. 5-175.1.5FHWA Regression Equations . 5-17SCS GRAPHICAL PEAK DISCHARGE METHOD. 5-195.2.1Runoff Depth Estimation. 5-195.2.2Soil Group Classification. 5-215.2.3Cover Complex Classification. 5-215.2.4Curve Number Tables. 5-215.2.5Estimation of CN Values for Urban Land Uses. 5-255.2.6Effect of Unconnected Impervious Area on Curve Numbers . 5-275.2.7Ia/P Parameter . 5-275.2.8Peak Discharge Estimation. 5-27RATIONAL METHOD. 5-315.3.1Assumptions . 5-315.3.2Estimating Input Requirements. 5-315.3.3Check for Critical Design Condition . 5-32INDEX FLOOD METHOD . 5-365.4.1Procedure for Analysis. 5-365.4.2Other Considerations. 5-38PEAK DISCHARGE ENVELOPE CURVES . 5-38CHAPTER 6 DESIGN HYDROGRAPHS . 6-16.1UNIT HYDROGRAPH ANALYSIS . 6-36.1.1Assumptions . 6-36.1.2Unit Hydrograph Definitions. 6-56.1.3Convolution. 6-66.1.4Analysis of Unit Hydrographs . 6-106.1.4.1Base Flow Separation. 6-106.1.4.2Determination of the Unit Hydrograph . 6-116.1.4.3Estimation of Losses. 6-116.1.4.4Rainfall Excess Hyetograph and Duration . 6-136.1.4.5Illustration of the UH Analysis Process . 6-136.1.5Derivation of a Unit Hydrograph from a Complex Storm . 6-216.1.6Averaging Storm-Event Unit Hydrographs. 6-266.1.7Unit Hydrograph Limitations . 6-316.2DEVELOPMENT OF A DESIGN STORM . 6-316.2.1Constant-Intensity Design Storm . 6-326.2.2The SCS 24-Hour Storm Distributions. 6-326.2.3Depth-Area Adjustments. 6-396.2.4Design Storm From Measured Storm Data . 6-406.2.5Design Storm by Triangular Hyetograph . 6-406.3DESIGN HYDROGRAPH SYNTHESIS . 6-426.3.1S-Hydrograph Method . 6-466.3.2Snyder Unit Hydrograph . 6-516.3.3SCS Unit Hydrograph . 6-586.3.4Rainfall Excess Determination: SCS Method . 6-646.4OTHER CONSIDERATIONS . 6-676.4.1Time-Area Unit Hydrographs . 6-676.4.2Hydrograph Development Using Assumptions Inherent in theRational Method. 6-696.4.3Design Hydrographs by Transposition. 6-70-vi-