Guidance for Design Hydrology for Stream Restoration and Channel Stability (2017)

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2017 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 RESEARCH REPORT 853 Guidance for Design Hydrology for Stream Restoration and Channel Stability Brian Bledsoe College of engineering University of georgia Athens, GA Dan Baker Peter Nelson Tyler Rosburg Joel Sholtes Travis Stroth Department of Civil anD environmental engineering ColoraDo state University Fort Collins, CO Subscriber Categories Hydraulics and Hydrology 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 is the most effective way to solve 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 results in increasingly complex problems of wide inter- est to highway authorities. These problems are best studied through a coordinated program of cooperative research. Recognizing this need, the leadership of the American Association of State Highway and Transportation Officials (AASHTO) in 1962 ini- tiated an objective national highway research program using modern scientific techniques—the National Cooperative Highway Research Program (NCHRP). NCHRP is supported on a continuing basis by funds from participating member states of AASHTO and receives the full cooperation and support of the Federal Highway Administration, United States Department of Transportation. The Transportation Research Board (TRB) of the National Academies of Sciences, Engineering, and Medicine was requested by AASHTO to administer the research program because of TRB’s recognized objectivity and understanding of modern research practices. TRB is uniquely suited for this purpose for many reasons: TRB maintains an extensive com- mittee structure from which authorities on any highway transportation subject may be drawn; TRB possesses avenues of communications and cooperation with federal, state, and local governmental agencies, univer- sities, and industry; TRB’s relationship to the National Academies is an insurance of objectivity; and TRB maintains a full-time staff of special- ists in highway transportation matters to bring the findings of research directly to those in a position to use them. The program is developed on the basis of research needs identified by chief administrators and other staff of the highway and transporta- tion departments and by committees of AASHTO. Topics of the highest merit are selected by the AASHTO Standing Committee on Research (SCOR), and each year SCOR’s recommendations are proposed to the AASHTO Board of Directors and the National Academies. Research projects to address these topics are defined by NCHRP, and qualified research agencies are selected from submitted proposals. Administra- tion and surveillance of research contracts are the responsibilities of the National Academies and TRB. The needs for highway research are many, and NCHRP can make significant contributions to solving 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 research 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 by going to http://www.national-academies.org and then searching for TRB Printed in the United States of America NCHRP RESEARCH REPORT 853 Project 24-40 ISSN 2572-3766 (Print) ISSN 2572-3774 (Online) ISBN 978-0-309-44655-6 Library of Congress Control Number 2017951105 © 2017 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, FRA, FTA, Office of the Assistant Secretary for Research and Technology, PHMSA, or TDC 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 research 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 National Academies of Sciences, Engineering, and Medicine. 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 Academies of Sciences, Engineering, and Medicine; or the program sponsors. The Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; and the sponsors of the National Cooperative Highway Research Program do not endorse products or manufacturers. Trade or manufacturers’ names appear herein solely because they are considered essential to the object of the report.

The National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, non- governmental institution to advise the nation on issues related to science and technology. Members are elected by their peers for outstanding contributions to research. Dr. Marcia McNutt is president. The National Academy of Engineering was established in 1964 under the charter of the National Academy of Sciences to bring the practices of engineering to advising the nation. Members are elected by their peers for extraordinary contributions to engineering. Dr. C. D. Mote, Jr., is president. The National Academy of Medicine (formerly the Institute of Medicine) was established in 1970 under the charter of the National Academy of Sciences to advise the nation on medical and health issues. Members are elected by their peers for distinguished contributions to medicine and health. Dr. Victor J. Dzau is president. The three Academies work together as the National Academies of Sciences, Engineering, and Medicine to provide independent, objective analysis and advice to the nation and conduct other activities to solve complex problems and inform public policy decisions. The National Academies also encourage education and research, recognize outstanding contributions to knowledge, and increase public understanding in matters of science, engineering, and medicine. Learn more about the National Academies of Sciences, Engineering, and Medicine at www.national-academies.org. The Transportation Research Board is one of seven major programs of the National Academies of Sciences, Engineering, and Medicine. The mission of the Transportation Research Board is to increase the benefits that transportation contributes to society by providing leadership in transportation innovation and progress through research and information exchange, conducted within a setting that is objective, interdisciplinary, and multimodal. The Board’s varied committees, task forces, and panels 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 individuals interested in the development of transportation. Learn more about the Transportation Research Board at www.TRB.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 24-40 by the Department of Civil and Environmental Engineering at Colorado State University (CSU). CSU was the contractor and fiscal administrator for this study. Dr. Brian Bledsoe, P.E. (Professor), was the project director and primary principal investigator; Dr. Peter Nelson (Assistant Professor) and Dr. Daniel Baker (Research Scientist) were co-principal inves- tigators. The other authors of this report are graduate research assistants: Tyler Rosburg (MS candidate), Joel Sholtes (PhD candidate), and Travis Stroth (MS candidate) at CSU. The work was done under the general supervision of the primary principal investigator and two co-principal investigators. CRP STAFF FOR NCHRP RESEARCH REPORT 853 Christopher J. Hedges, Director, Cooperative Research Programs Lori L. Sundstrom, Deputy Director, Cooperative Research Programs Waseem Dekelbab, Senior Program Officer Megan A. Chamberlain, Senior Program Assistant Eileen P. Delaney, Director of Publications Natalie Barnes, Senior Editor NCHRP PROJECT 24-40 PANEL Field of Soils and Geology—Area of Mechanics and Foundations Casey M. Kramer, Northwest Hydraulic Consultants, Olympia, WA (Chair) Andrea C. H. Hendrickson, Minnesota DOT, Oakdale, MN Paul A. DeBarry, NTM Engineering Inc., Dillsburg, PA William B. Fletcher, II, Oregon DOT, Salem, OR George H. Long, New York State DOT, Albany, NY Jonathan C. Mallard, Virginia DOT, Richmond, VA Veronica Ghelardi, FHWA Liaison Stephen F. Maher, TRB Liaison

This guidance describes scientifically supported methods for defining the design hydrology for stream restoration and channel stability at stream crossings with a set of decision support tools that are both science-based and practical in guiding users to an appropriate combination of design tools and depth of analysis for design hydrology in a given hydrologic and geo- morphic setting. Specifically, the guidance and tools provide support in: (1) assessing the current conditions adjacent to a stream crossing and in the upstream watershed to determine design effort, (2) performing the appropriate hydrological and geomorphic analysis using a set of analytical and analog tools, and (3) designing the channel through the stream crossing for stability and sediment balance. The hydrologic metrics and tools developed in this proj- ect provide a general framework and stronger physical basis for design hydrology at stream crossings, including locations where watershed land use is changing. This report will be of immediate interest to hydraulic engineers. Significant resources are being applied by public and private highway and rail organizations to design and construct restored streams in disturbed watersheds as well as to provide for stable transportation crossings (bridges and culverts) of streams. Lacking in this effort was a scientifically supported method for (1) defining the design hydrology for such efforts and (2) understanding how that design hydrology might change with land use changes. Much stream restoration and stream stability work is performed at sites where the upstream watershed is experiencing changes in land use and runoff characteristics. These changes affect not only peak discharges, but also flow duration relationships, total runoff volume, stream power, sediment supply, and sediment transport. Increases or decreases in net sediment transport potential imply changes in the character of channel-forming discharge, consequently affecting both the geometry and stability of existing stream channels. Understanding how hydrology may vary over time or with changes in the watershed is a weak link in protecting highway infrastructure from the effects of stream instability. Research was needed to quantify the effect of these hydrologic changes on the channel- forming discharges and the resulting channel geometry that are important in designing culverts and bridges for long-term performance. Research was performed under NCHRP Project 24-40 by Colorado State University to develop guidance based on a scientifically supported method for determining the design hydrology for stream restoration and channel stability at stream crossings and for under- standing how that design hydrology might change over time. Several decision support/analysis tools were developed to improve and facilitate design hydrology analyses: (1) a decision tree to be used with web-based hydrologic analysis tools (erams.com) for generating design hydrology metrics under existing and future land use scenarios, (2) guidance on relating F O R E W O R D By Waseem Dekelbab Staff Officer Transportation Research Board

channel response potential to an appropriate level of design analysis, (3) guidance on select- ing analog reaches, (4) guidance on performing rapid geomorphic assessments of channel instability in the field, and (5) a spreadsheet-based Capacity Supply Ratio Tool (CSR Tool) for computing analytical channel designs that account for the full spectrum of sediment transporting events. This research report is Appendix C of the research agency’s final report, which documents the entire research effort. The research agency’s final report including Appendices A, B, and D is available on the summary web page for NCHRP Research Report 853. The three appendices are titled as follow: • Appendix A—Site-Specific Information for Study Sites • Appendix B—Tutorials for the use of eRAMS (the Environmental Resource Assessment & Management System) • Appendix D—Reference Manual: CSR Tool The CSR Tool and two illustrative examples for different stream types (sand bed and gravel/ cobble bed) are also available on the summary web page for NCHRP Research Report 853.

1 Chapter 1 Introduction 2 Chapter 2 The Design Hydrology Process 2 2.1 Overview of the Design Hydrology Process 2 2.2 Overview of Phases 1 and 2 3 2.3 Phase 1: Assess the Current Conditions Adjacent to the Stream Crossing and in the Watershed to Determine Design Effort 3 2.3.1 Bed Material Versus Flashiness 4 2.3.2 w* Versus Flashiness 5 2.3.3 Simplified Rapid Geomorphic Assessment 7 2.3.4 Analog Reach Guidance 8 2.3.5 Selection of the Design Hydrology Approach 10 2.4 Phase 2: Design the Stream Channel Through the Stream Crossing 10 2.4.1 Establish a Sediment Supply Reach 11 2.4.2 Evaluate Whether Additional Field Reconnaissance Is Needed 11 2.4.3 Perform Channel Design Using the Set of Recommended Methods 11 2.4.4 Compare Channel Designs to Analog Design(s) 13 2.4.5 Select a Robust Design 13 2.5 Limits to the Application of This Process 14 Chapter 3 Guidance/Examples 14 3.1 Guidance/Examples Overview 14 3.2 Guidance for Calculating the Half-Load Discharge 14 3.2.1 Step 1: Projecting Future Streamflow Behavior Caused by Changing Land Use 15 3.2.2 Step 2: Choosing a Reference Streamflow Gage and Indexing Flow Records 16 3.2.3 Step 3: Using a Hydrologic Model to Produce Streamflow Time Series from Precipitation Records 16 3.2.4 Step 4: Checking the Stationarity of Streamflow Records 16 3.2.5 Step 5: Calculating the Richards-Baker Flashiness Index 16 3.2.6 Step 6: Obtaining a Sediment Rating Curve 17 3.2.7 Step 7: Determining the Appropriate Resolution of Streamflow Data 18 3.3 Examples 18 3.3.1 Example 1: Projecting Hydrologic Changes Caused by Changing Land Use for the Fourmile Creek Watershed in Central Iowa (Step 1) 19 3.3.2 Example 2: Rainfall-Runoff Modeling of Box Elder Creek (Step 3) 23 3.3.3 Example 3: Using eRAMS to Calculate the Richards-Baker Flashiness Index of the Iowa River near Iowa City, Iowa (Step 5) 23 3.3.4 Example 4: Using the Qs50 Decision Tree for Determining Qs50 for the Iowa River near Iowa City, Iowa (Steps 1 Through 5) C O N T E N T S

28 Chapter 4 User Guidance for the CSR Tool 28 4.1 Startup Tab 33 4.2 Quick Reference Guide Tab 33 4.3 Hydrology Tab 35 4.4 Hydrology FDC Tab 36 4.5 Grain Size Distribution Tab 37 4.6 Supply Reach Tab 39 4.7 Design Reach Tab 40 4.8 Results Tab 41 4.9 Detailed Results Tab 42 Chapter 5 CSR Tool Examples 42 5.1 Sand Bed 42 5.1.1 Startup Tab 42 5.1.2 Hydrology Tab 46 5.1.3 Supply Reach Tab 49 5.1.4 Design Reach Tab 50 5.1.5 Results Tab 51 5.1.6 Detailed Results Tab 52 5.2 Gravel/Cobble Bed 52 5.2.1 Startup Tab 55 5.2.2 Hydrology Tab 57 5.2.3 Grain Size Distribution Tab 58 5.2.4 Supply Reach Tab 60 5.2.5 Design Reach Tab 61 5.2.6 Results Tab 63 5.2.7 Detailed Results Tab 64 References 68 Abbreviations, Acronyms, Initialisms, and Symbols