Publication No. FHWA-NHI-02-001 October 2002 U.S. Department of Transportation Federal Highway Administration Hydraulic Design Series No. 2, Second Edition Highway Hydrology National Highway Institute Technical Report Documentation Page 1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. FHWA-NHI-02-001 HDS-2 4. Title and Subtitle 5. Report Date Highway Hydrology October 2002 Hydraulic Design Series Number 2, Second Edition 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No. Richard H. McCuen, Peggy A. Johnson, Robert M. Ragan 9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) Greenhorne and O’Mara, Inc 9001 Edmonston Road 11. Contract or Grant No. Greenbelt, Maryland 20770 DTFH61-95-C-00080 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered Federal Highway Administration Final Report National Highway Institute Office of Bridge Technology 1st Edition: Oct 1992 – Jun 1996 4600 North Fairfax Drive 400 Seventh Street 2nd Edition – Nov 2000 – Nov 2001 Suite 800 Room 3202 14. Sponsoring Agency Code Arlington, Virginia 22203 Washington D.C. 20590 15. Supplementary Notes Project Manager: Joe Krolak – FHWA Eastern Resource Center Technical Editor, second edition: Roger T. Kilgore Technical Assistance, second edition: Dan Ghere, Paul Koch, Imtiaz Shah, Sung-Hee Kim 16. Abstract This document discusses the physical processes of the hydrologic cycle that are important to highway engineers. These processes include the approaches, methods and assumptions applied in design and analysis 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. The document describes the concept and several approaches for determining time of concentration. The peak discharge methods discussed include log Pearson type III, regression equations, the SCS graphical method (curve number method), and rational method. The technical discussion of each peak flow approach also includes urban development applications. The document presents common storage and channel routing techniques related to highway drainage hydrologic analyses. The document describes methods used in the planning and design of stormwater management facilities. Special topics in hydrology include discussions of arid lands hydrology, wetlands hydrology, snowmelt hydrology, and hydrologic modeling, including geographic information system approaches and applications. This edition includes new sections on wetlands hydrology and snowmelt hydrology, an expanded section on arid lands hydrology, corrections of minor errors, and inclusion of dual units. 17. Key Word 18. Distribution Statement Hydrology, frequency analysis, peak discharge This document is available to the public from the estimation, urban hydrology, hydrograph National technical Information Service, Springfield, development, storage and channel routing, Virginia, 22151 stormwater management, arid lands hydrology, wetland hydrology, snowmelt hydrology, GIS 19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price Unclassified Unclassified 424 Form DOT F 1700.7 (8-72) Reproduction of completed page authorize ACKNOWLEDGMENTS First Edition The 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 recognize and 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 draft documents. Ms. Alison R. Montgomery and Ms. Florence Kemerer drafted figures. Ms. Florence Kemerer typed and formatted the text. Second Edition This 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 to readers. Mr. Larry Jones was the FHWA COTR for the second edition. Mr. Philip Thompson of FHWA 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 their contributions in the production of this second edition: Ms. Patricia Padgett-Neal, for word processing, Ms. Julie Liptak, for graphic design, and Ms. Deb Daly, for editorial review. Gary Lewis and Bruce Curtis, of Parsons, Inc., provided significant contributions to the new special topics chapter. Thank you very much! -i- -ii- TABLE OF CONTENTS Page ACKNOWLEDGMENTS .................................................................................................... i TABLE OF CONTENTS....................................................................................................iii LIST OF TABLES..............................................................................................................ix LIST OF FIGURES ..........................................................................................................xii GLOSSARY .....................................................................................................................xv CHAPTER 1 INTRODUCTION ...................................................................................... 1-1 1.1 HYDROLOGIC CYCLE ...................................................................................... 1-1 1.2 HYDROLOGY OF HIGHWAY STREAM CROSSINGS...................................... 1-3 1.2.1 Elements of the Hydrologic Cycle Pertinent to Stream Crossings..... 1-3 1.2.2 Overview of Hydrology as Applied to Stream Crossings ................... 1-3 1.2.3 Channelization................................................................................... 1-5 1.2.4 Detention Storage.............................................................................. 1-6 1.2.5 Diversions and Dam Construction ..................................................... 1-6 1.2.6 Natural Disasters ............................................................................... 1-6 1.3 GENERAL DATA REQUIREMENTS.................................................................. 1-7 1.4 SOLUTION METHODS...................................................................................... 1-7 1.4.1 Deterministic Methods ....................................................................... 1-7 1.4.2 Statistical Methods............................................................................. 1-7 1.5 ANALYSIS VERSUS SYNTHESIS .................................................................... 1-8 1.5.1 A Conceptual Representation of Analysis and Synthesis.................. 1-8 1.5.2 Examples of Analysis and Synthesis in Hydrologic Design ............... 1-9 CHAPTER 2 RAINFALL/RUNOFF PROCESSES ......................................................... 2-1 2.1 PRECIPITATION................................................................................................ 2-1 2.1.1 Forms of Precipitation........................................................................ 2-1 2.1.2 Types of Precipitation (by Origin) ...................................................... 2-1 2.1.2.1 Convective Storms.......................................................... 2-2 2.1.2.2 Orographic Storms.......................................................... 2-2 2.1.2.3 Cyclonic Storms.............................................................. 2-2 2.1.2.4 Hurricanes and Typhoons............................................... 2-3 2.1.3 Characteristics of Rainfall Events ...................................................... 2-3 2.1.4 Intensity-Duration-Frequency Curves ................................................ 2-9 2.2 HYDROLOGIC ABSTRACTIONS .................................................................... 2-10 2.2.1 Evaporation...................................................................................... 2-10 2.2.2 Transpiration.................................................................................... 2-10 2.2.3 Interception...................................................................................... 2-10 2.2.4 Infiltration ......................................................................................... 2-11 2.2.5 Depression Storage ......................................................................... 2-11 2.2.6 Detention Storage............................................................................ 2-11 2.2.7 Total Abstraction Methods ............................................................... 2-11 2.3 CHARACTERISTICS OF RUNOFF ................................................................. 2-11 2.3.1 Peak Discharge ............................................................................... 2-12 2.3.2 Time Variation (Hydrograph) ........................................................... 2-12 2.3.3 Stage-Discharge.............................................................................. 2-12 2.3.4 Total Volume.................................................................................... 2-13 2.3.5 Frequency........................................................................................ 2-14 2.3.6 Return Period..................................................................................