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N A T I O N A L C O O P E R A T I V E H I G H W A Y R E S E A R C H P R O G R A M NCHRP REPORT 795 Design Methods for In-Stream Flow Control Structures Fotis Sotiropoulos St. Anthony FAllS lAborAtory DepArtment oF Civil, environmentAl, AnD Geo-enGineerinG UniverSity oF minneSotA Minneapolis, MN Panayiotis Diplas DepArtment oF Civil AnD environmentAl enGineerinG lehiGh UniverSity Bethlehem, PA Subscriber Categories Hydraulics and Hydrology TRANSPORTAT ION RESEARCH BOARD WASHINGTON, D.C. 2014 www.TRB.org Research sponsored by the American Association of State Highway and Transportation Officials in cooperation with the Federal Highway Administration
NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Systematic, well-designed research provides the most effective approach to the solution of many problems facing highway administrators and engineers. Often, highway problems are of local interest and can best be studied by highway departments individually or in cooperation with their state universities and others. However, the accelerating growth of highway transportation develops increasingly complex problems of wide interest to highway authorities. These problems are best studied through a coordinated program of cooperative research. In recognition of these needs, the highway administrators of the American Association of State Highway and Transportation Officials initiated in 1962 an objective national highway research program employing modern scientific techniques. This program is supported on a continuing basis by funds from participating member states of the Association and it receives the full cooperation and support of the Federal Highway Administration, United States Department of Transportation. The Transportation Research Board of the National Academies was requested by the Association to administer the research program because of the Boardâs recognized objectivity and understanding of modern research practices. The Board is uniquely suited for this purpose as it maintains an extensive committee structure from which authorities on any highway transportation subject may be drawn; it possesses avenues of communications and cooperation with federal, state and local governmental agencies, universities, and industry; its relationship to the National Research Council is an insurance of objectivity; it maintains a full-time research correlation staff of specialists in highway transportation matters to bring the findings of research directly to those who are in a position to use them. The program is developed on the basis of research needs identified by chief administrators of the highway and transportation departments and by committees of AASHTO. Each year, specific areas of research needs to be included in the program are proposed to the National Research Council and the Board by the American Association of State Highway and Transportation Officials. Research projects to fulfill these needs are defined by the Board, and qualified research agencies are selected from those that have submitted proposals. Administration and surveillance of research contracts are the responsibilities of the National Research Council and the Transportation Research Board. The needs for highway research are many, and the National Cooperative Highway Research Program can make significant contributions to the solution of highway transportation problems of mutual concern to many responsible groups. The program, however, is intended to complement rather than to substitute for or duplicate other highway research programs. Published reports of the NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM are available from: Transportation Research Board Business Office 500 Fifth Street, NW Washington, DC 20001 and can be ordered through the Internet at: http://www.national-academies.org/trb/bookstore Printed in the United States of America NCHRP REPORT 795 Project 24-33 ISSN 0077-5614 ISBN 978-0-309-30821-2 Library of Congress Control Number 20149455582 © 2014 National Academy of Sciences. All rights reserved. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FMCSA, FTA, or Transit Development Corporation endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. NOTICE The project that is the subject of this report was a part of the National Cooperative Highway Research Program, conducted by the Transportation Research Board with the approval of the Governing Board of the National Research Council. The members of the technical panel selected to monitor this project and to review this report were chosen for their special competencies and with regard for appropriate balance. The report was reviewed by the technical panel and accepted for publication according to procedures established and overseen by the Transportation Research Board and approved by the Governing Board of the National Research Council. The opinions and conclusions expressed or implied in this report are those of the researchers who performed the research and are not necessarily those of the Transportation Research Board, the National Research Council, or the program sponsors. The Transportation Research Board of the National Academies, the National Research Council, and the sponsors of the National Cooperative Highway Research Program do not endorse products or manufacturers. Trade or manufacturersâ names appear herein solely because they are considered essential to the object of the report.
The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Ralph J. Cicerone is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. C. D. Mote, Jr., is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Victor J. Dzau is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academyâs purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Ralph J. Cicerone and Dr. C. D. Mote, Jr., are chair and vice chair, respectively, of the National Research Council. The Transportation Research Board is one of six major divisions of the National Research Council. The mission of the Transporta- tion Research Board is to provide leadership in transportation innovation and progress through research and information exchange, conducted within a setting that is objective, interdisciplinary, and multimodal. The Boardâs varied activities annually engage about 7,000 engineers, scientists, and other transportation researchers and practitioners from the public and private sectors and academia, all of whom contribute their expertise in the public interest. The program is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transportation, and other organizations and individu- als interested in the development of transportation. www.TRB.org www.national-academies.org
C O O P E R A T I V E R E S E A R C H P R O G R A M S AUTHOR ACKNOWLEDGMENTS The research reported herein was performed under NCHRP Project 24-33 by the St. Anthony Falls Laboratory (SAFL) at the University of Minnesota (UMN). UMN was the contractor for this study. Dr. Fotis Sotiropoulos, James L. Record Professor of Civil Engineering and Director of the St. Anthony Falls Laboratory, was the Principal Investigator. Dr. Panayiotis Diplas, P. C. Rossin Professor and Chair, Water Resources Engineering, Lehigh University (formerly Professor of Civil Engineering at Virginia Tech for the duration of this study) was the co-Principal Investigator. Other contributors to this report were Dr. Jessica Kozarek, Research Associate at SAFL, Ali Khosronejad, Research Associate at SAFL, Craig Hill (SAFL), Dr. Seokkoo Kang (former PhD student, SAFL), Read Plott (former MS student, Virginia Tech), Rajan Jha (former MS student, Virginia Tech), Ryan Radspinner (former MS student, Virginia Tech), and Dr. Anne Lightbody (former Research Associate, SAFL). CRP STAFF FOR NCHRP REPORT 795 Christopher W. Jenks, Director, Cooperative Research Programs Christopher Hedges, Manager, National Cooperative Highway Research Program David A. Reynaud, Senior Program Officer Megan A. Chamberlain, Senior Program Assistant Eileen P. Delaney, Director of Publications Doug English, Editor NCHRP PROJECT 24-33 PANEL Soils and GeologyâMechanics and Foundations Michael Fazio, City of Bluffdale, Utah, Bluffdale, UT (Chair) Eric R. Brown, Federal Highway Administration, Baltimore, MD Petronella L. DeWall, Minnesota DOT, Oakdale, MN Stanley C. Hopfe, Texas DOT, Austin, TX Peggy A. Johnson, Pennsylvania State University, University Park, PA Andrew T. Nottingham, North Carolina DOT, Raleigh, NC David Stolpa, TRC Companies Inc., Austin, TX Kornel Kerenyi, FHWA Liaison Stephen F. Maher, TRB Liaison
F O R E W O R D This report presents design guidelines for in-stream flow control structures that are often used to limit lateral migration and reduce bank erosion. The guidelines include a descrip- tion of conditions under which in-stream flow control structures are either successful or not effective in providing protection against erosion and scour and in performing applicable habitat restoration functions. Unlike rip-rap, which strengthens the bank to withstand the applied hydrodynamic forces, in-stream flow control structures alter the stream-flow pat- terns to shift the high-velocity thread away from the bank. This report will be valuable to hydraulic engineers by facilitating the use of an alternative method to reduce stream-bank erosion and scour. To design economic in-stream flow control structures with confidence, hydraulic engineers need sound engineering design, installation, and maintenance criteria. These criteria must be supported by quantitative optimization of parameters, such as the amount of construc- tion materials, life-cycle cost, size, spacing, and foundation depth, and their influence on the stream habitat, scour depth, sediment transport, and long-term structure and channel stability. The objective of NCHRP Project 24-33 was to develop quantitative engineering guide- lines, design methods, and recommended specifications for in-stream, low-flow structures that address (1) erosion protection, channel stability, sediment transport, and scour stability of the stream; (2) cost-effectiveness, as well as long-term performance in terms of the low- flow structure stability, durability, and survivability; (3) recommended installation practices; and (4) maintenance requirements. To develop these guidelines, researchers at the University of Minnesotaâs St. Anthony Falls Laboratory and Virginia Tech coupled an in-depth review of the current use of in-stream structures with a comprehensive study of five of the most commonly used in-stream struc- tures using physical and numerical experiments. They conducted physical experiments at two scales: a laboratory-scale straight-channel flume and an outdoor field-scale meandering experimental channel. After extensive validation using the physical experimental results, a state-of-the-art coupled hydrodynamic and bed morphodynamic model was used to inves- tigate the performance of various structure configurations under different geomorphic settings. This model, dubbed the Virtual Stream Lab (VSL3D), is capable of simulating the complex three-dimensional flows around in-stream structures and their interaction with the bed. By David A. Reynaud Staff Officer Transportation Research Board
C O N T E N T S 1 Summary 2 Chapter 1 Background 4 Chapter 2 Research Approach 4 2.1 Rock Vanes 5 2.2 J-Hook Vanes 6 2.3 Bendway Weirs/Stream Barbs 6 2.4 Cross Vanes 7 2.5 W-Weirs 9 Chapter 3 Numerical Methodology for Developing Design Guidelines for Single-Arm Structures 12 3.1 VSL3D Results for Rock Vanes 20 3.2 VSL3D Results for J-Hook Vanes 25 3.3 VSL3D Results for Bendway Weirs/Stream Barbs 35 Chapter 4 Numerical Methodology for Developing Design Guidelines for Sill Structures 35 4.1 VSL3D Results for Cross Vanes 41 4.2 VSL3D Results for W-Weirs 44 Chapter 5 Comparison of In-Stream Flow Control Structure Types 44 5.1 Bank Protection 44 5.2 Scour Hole Dimensions 46 5.3 Flanking Potential 46 5.4 Hydrodynamic Forces on Rock Structures 49 5.5 Backwater and Water Surface Elevation Impacts 54 Chapter 6 Evaluation of Current Guidelines 54 6.1 Length of Bank Protection in Meandering Channels 54 6.2 Spacing and Number of Structures 56 6.3 Footer Rock Depths 58 Chapter 7 Compilation of Experimental and Numerical Results to Develop Design Guidelines 58 7.1 Rock Vanes/J-Hooks 60 7.2 Bendway Weirs/Stream Barbs 62 7.3 Sill Structures (Cross Vanes/W-Weirs) 62 7.4 Structure Selection 64 References 66 Appendix F Design Guidelines for In-Stream Flow Control Structures Appendices A through E and G are posted on the project web page at http://apps.trb.org/cmsfeed/TRBNetProject Display.asp?ProjectID=1641.
A: cross-sectional area (of rock) B: width BW: bendway weir Cd: drag coefficient CV: cross vane (U-shaped) CVA: cross vane (A-shaped) D50: median grain size D100: largest rock size F: drag force on a single rock Fo: representative drag force on a single rock using bulk velocity H: flow depth ISL: indoor StreamLab JH: J-hook L: distance along structure Ld: downstream bank length Le: effective length perpendicular to flow Ls: structure length Lu: upstream bank length OSL: outdoor StreamLab Qbf: bankfull discharge Rc: radius of curvature RV: rock vane ScMAX: maximum scour compared to average bed elevation in baseline channel Sct: scour at the structure tip S: slope TKE: turbulence kinetic energy u: local velocity magnitude Vs: structure spacing WW: W-weir Zbed: time-averaged quasi-equilibrium bed elevation (Zbed = 0 at initial flat bed) DZ: Zbed with structure minus Zbed for baseline case Zrms: RMS of bed elevation f: angle of repose r: density of water l: wavelength L i s t o f A b b r e v i A t i o n s A n d v A r i A b L e s
