NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competencies and with regard for appropriate balance.
Support for this project was provided by U.S. Army Corps of Engineers under DACW05-98-C-0031.
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COMMITTEE ON AMERICAN RIVER FLOOD FREQUENCIES
KENNETH W. POTTER, Chair,
University of Wisconsin, Madison
SANDRA O. ARCHIBALD,
University of Minnesota, Minneapolis
DUANE C. BOES,
Colorado State University, Fort Collins
TIMOTHY A. COHN,
U.S. Geological Survey, Reston, Virginia
S. ROCKY DURRANS,
University of Alabama, Tuscaloosa
C. THOMAS HAAN,
Oklahoma State University, Stillwater
ROBERT D. JARRETT,
U.S. Geological Survey, Lakewood, Colorado
UPMANU LALL,
Utah State University, Logan
KELLY T. REDMOND,
Desert Research Institute, Reno, Nevada
JERY R. STEDINGER,
Cornell University, Ithaca, New York
Consultant
CHARLES A. RODGERS,
University of Wisconsin, Madison
Staff
STEPHEN D. PARKER, Study Director
MARK GIBSON, Research Associate
ELLEN A. DE GUZMAN, Senior Project Assistant
WATER SCIENCE AND TECHNOLOGY BOARD
HENRY J. VAUX, Jr., Chair,
University of California, Oakland
CAROL A. JOHNSTON, Vice Chair,
University of Minnesota, Duluth
RICHELLE ALLEN-KING,
Washington State University, Pullman
JOHN S. BOYER,
University of Delaware, Lewes
JOHN BRISCOE,
The World Bank, Washington, D.C.
DENISE FORT,
University of New Mexico, Albuquerque
EVILLE GORHAM,
University of Minnesota, St. Paul
CHARLES D. D. HOWARD,
Charles Howard and Associates, Ltd., Victoria, British Columbia
WILLIAM A. JURY,
University of California, Riverside
WILLIAM M. LEWIS, Jr.,
University of Colorado, Boulder
GARY S. LOGSDON,
Black & Veatch, Cincinnati, Ohio
RICHARD LUTHY,
Carnegie Mellon University, Pittsburgh, Pennsylvania
JOHN W. MORRIS,
J.W. Morris, Ltd., Arlington, Virginia
CHARLES R. O'MELIA,
The Johns Hopkins University, Baltimore, Maryland
PHILIP A. PALMER,
E.I. du Pont de Nemours & Co., Wilmington, Delaware
REBECCA T. PARKIN,
The George Washington University, Washington, D.C.
JOAN B. ROSE,
University of South Florida, St. Petersburg
ERIC F. WOOD,
Princeton University, Princeton, New Jersey
Staff
STEPHEN D. PARKER, Director
JACQUELINE A. MACDONALD, Associate Director
CHRIS ELFRING, Senior Staff Officer
LAURA J. EHLERS, Staff Officer
JEFFREY W. JACOBS, Staff Officer
MARK GIBSON, Research Associate
JEANNE AQUILINO, Administrative Associate
ANITA A. HALL, Administrative Assistant
ELLEN A. DE GUZMAN, Senior Project Assistant
KIMBERLY SWARTZ, Project Assistant
COMMISSION ON GEOSCIENCES, ENVIRONMENT, AND RESOURCES
GEORGE M. HORNBERGER, Chair,
University of Virginia, Charlottesville
PATRICK R. ATKINS,
Aluminum Company of America, Pittsburgh, Pennsylvania
JERRY F. FRANKLIN,
University of Washington, Seattle
B. JOHN GARRICK,
PLG, Inc., Newport Beach, California
THOMAS E. GRAEDEL,
Yale University, New Haven, Connecticut
DEBRA KNOPMAN,
Progressive Policy Institute, Washington, D.C.
KAI N. LEE,
Williams College, Williamstown, Massachusetts
JUDITH E. McDOWELL,
Woods Hole Oceanographic Institution, Massachusetts
RICHARD A. MESERVE,
Covington & Burling, Washington, D.C.
HUGH C. MORRIS,
Canadian Global Change Program, Delta, British Columbia
RAYMOND A. PRICE,
Queen's University at Kingston, Ontario
H. RONALD PULLIAM,
University of Georgia, Athens, Georgia
THOMAS C. SCHELLING,
University of Maryland, College Park
VICTORIA J. TSCHINKEL,
Landers and Parsons, Tallahassee, Florida
E-AN ZEN,
University of Maryland, College Park
MARY LOU ZOBACK,
U.S. Geological Survey, Menlo Park, California
Staff
ROBERT M. HAMILTON, Executive Director
GREGORY H. SYMMES, Associate Executive Director
JEANETTE SPOON, Administrative & Financial Officer
SANDI FITZPATRICK, Administrative Associate
MARQUITA SMITH, Administrative Assistant/Technology Analyst
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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. William A. Wulf 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. Kenneth I. Shine is president of the Institute of Medicine.
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Preface
This report is the result of an intensive eight-month study effort by the Committee on American River Flood Frequencies, a group of experts organized to assist the U.S. Army Corps of Engineers (USACE) by providing an independent scientific assessment of flood frequency relationships for the American River at Sacramento, California. The study was designed and the committee formed under the auspices of the Water Science and Technology Board (WSTB) of the National Research Council (NRC). It extends the work of the former WSTB Committee on Flood Control Alternatives in the American River Basin (whose findings were published in 1995) and aims to achieve better estimation of flood frequency relationships for the American River in light of a major flood in January 1997 and other technical considerations. In its review, the committee considered issues such as the following that were specified by the USACE as technically controversial in the agreement enabling support for the study:
- applicability of (the federally-prescribed) Bulletin 17-B based statistical approach;
- appropriateness of skew factor development;
- potential censoring of water year 1977 data, considering validity of Bulletin 17-B criteria;
- updated river basin probable maximum flood, and its supportive relationship to the selected flow frequency curve;
- methodologies to 'bend over' the less frequent portion of the flow frequency curve to reflect the American River basin's realistic maximum flow productivity;
- applicability of paleoflood methodologies to this flow frequency analysis; and
- climatologic/meteorologic/hydrologic trends and American River basin parameters that may influence the American River flow frequency curve.
This report's findings are based on a review of relevant technical literature, extensive flood frequency analyses by the committee, and deliberations among committee members.
The committee consisted of 10 volunteer experts in hydrologic and geophysical statistics, hydrologic engineering, geomorphology, hydroclimatology, climatology, and economics (see Appendix A). The committee incorporated input,
when appropriate, from a wide range of stakeholders and USACE personnel concerned about flood risk management for Sacramento and environmental quality of the American River and its tributaries. Much of this interaction with interested parties occurred at a committee-hosted workshop and meeting in Sacramento on July 12-15, 1998. At that workshop, the committee gathered input, deliberated on the issues, outlined this report, and took on work assignments. Following the meeting, the committee members made calculations and drafted and refined this report, which represents a consensus of our multidisciplinary committee.
The first chapter of this report provides a brief overview of the historical and ongoing development of flood control measures on the American River, associated technical issues, and policy implications. Chapter 2 provides a description of the data types that can be used in estimating flood exceedance probabilities for the American River. Chapter 3 presents and discusses the committee's flood frequency estimates for the American River. Chapter 4 reviews the meteorology of floods associated with the hydrologic cycle of the American River. Lastly, Chapter 5 provides a summary of the committee's findings and recommendations for the improvement of flood frequency analyses for the American River. The committee expects that its report will be helpful in planning for flood risk reduction in Sacramento, but so many general technical and policy issues presented themselves in Sacramento that, as the study progressed, we began to see our analyses as a case study with broader implications. We hope those with interests outside Sacramento will find our report useful.
Leading this project was a special pleasure. It is not often that one has the opportunity to address a problem as technically challenging and politically charged as the one assigned to our committee. To lead a group as experienced and intellectually powerful as ours was both an honor and a challenge. I am grateful for the opportunity to have led the members of this group, and I thank them for their many contributions. Our work was supported by three WSTB staff members, Ellen de Guzman, Mark Gibson, and Stephen Parker, and a consultant, Charles Rodgers of the University of Wisconsin, who were of great assistance in facilitating our work. On behalf of the committee and the Water Science and Technology Board, I also would like to express our appreciation to the fine staff of the U.S. Army Corps of Engineers with whom we interacted during this study. Our principal liaisons were Robert Childs and John Mack of the Sacramento District. Interaction with them and their colleagues at the district and at the Corps Hydrologic Engineering Center in Davis, California was critical to the success of this study. Additionally, the committee was briefed, informed, and assisted—principally at its July 1998 workshop—by numerous other individuals from other agencies and organizations familiar with the issues at hand. They are too numerous to list (more than 30) but we are indebted for the information and perspectives they provided.
The report has been reviewed by individuals chosen for their diverse perspectives and technical expertise, in accordance with procedures approved by the NRC's Report Review Committee. The purpose of this independent review is to provide candid and critical comments that will assist the authors and the NRC in making the published report as sound as possible and to ensure that the report meets institutional standards for objectivity, evidence, and responsiveness to the study charge. The content of the review comments and draft manuscripts remain confi-
dential to protect the integrity of the deliberative process. We wish to thank the following individuals for their participation in the review of this report: Joseph D. Countryman, consulting engineer, Sacramento, California; Katherine K. Hirschboeck, University of Arizona; George M. Hornberger, University of Virginia; Charles D. D. Howard, Charles Howard and Associates, Victoria, British Columbia; L. Allan James, University of South Carolina; William H. Kirby, U.S. Geological Survey, Reston, Virginia; and Rutherford H. Platt, University of Massachusetts. While these individuals provided many constructive comments and suggestions, responsibility for the final content of this report rests solely with the authoring committee and the NRC.
KENNETH W. POTTER, CHAIR
COMMITTEE ON AMERICAN RIVER FLOOD FREQUENCIES
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