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 the U.S. Army Corps of Engineers under DACW72-98-C-0003.
International Standard Book Number 0-309-07136-4
Library of Congress Catalog Card Number 00-108527
Risk Analysis and Uncertainty in Flood Damage Reduction Studies is available from the
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Sketch on the book cover is courtesy of the California State Library. It is a contemporary sketch of the city of Sacramento during the high water of the winter of 1849-1850.
Copyright 2000 by the National Academy of Sciences. All rights reserved.
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THE NATIONAL ACADEMIES
Advisors to the Nation on Science, Engineering, and Medicine
National Academy of Sciences
National Academy of Engineering
Institute of Medicine
National Research Council
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. Bruce M. Alberts 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 achievement 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.
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 Academy's 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. Bruce M. Alberts and Dr. William A. Wulf are chairman and vice chairman, respectively, of the National Research Council.
COMMITTEE ON RISK-BASED ANALYSES FOR FLOOD DAMAGE REDUCTION
GREGORY B. BAECHER, Chair,
University of Maryland, College Park
EFI FOUFOULA-GEORGIOU,
University of Minnesota, Minneapolis
RALPH L. KEENEY,
University of Southern California, Los Angeles
LESTER B. LAVE,
Carnegie Mellon University, Pittsburgh, Pennsylvania
HARRY F. LINS,
U.S. Geological Survey, Reston, Virginia
DANIEL P. LOUCKS,
Cornell University, Ithaca, New York
DAVID R. MAIDMENT,
University of Texas, Austin
MARTIN W. MCCANN,
Jack R. Benjamin and Associates, Inc., Menlo Park, California
JERY R. STEDINGER,
Cornell University, Ithaca, New York
BEN CHIE YEN,
University of Illinois, Urbana-Champaign
National Research Council Staff
JEFFREY W. JACOBS, Study Director
ELLEN A. DE GUZMAN, Senior Project Assistant
WATER SCIENCE AND TECHNOLOGY BOARD
HENRY J. VAUX, Jr., Chair,
Division of Agriculture and Natural Resources, University of California, Oakland
RICHARD G. LUTHY, Vice-Chair,
Stanford University, Stanford, California
RICHELLE M. ALLEN-KING,
Washington State University, Pullman
GREGORY B. BAECHER,
University of Maryland, College Park
JOHN BRISCOE,
The World Bank, Washington, D.C.
EFI FOUFOULA-GEORGIOU,
University of Minnesota, Minneapolis
STEVEN P. GLOSS,
University of Wyoming, Laramie
WILLIAM A. JURY,
University of California, Riverside
GARY S. LOGSDON,
Black & Veatch, Cincinnati, Ohio
DIANE M. MCKNIGHT,
University of Colorado, Boulder
JOHN W. MORRIS,
J.W. Morris Ltd., Arlington, Virginia
PHILIP A. PALMER,
(Retired) E.I. du Pont de Nemours & Co., Wilmington, Delaware
REBECCA T. PARKIN,
The George Washington University, Washington, D.C.
RUTHERFORD H. PLATT,
University Massachusetts, Amherst
JOAN B. ROSE,
University of South Florida, St. Petersburg
JERALD L. SCHNOOR,
University of Iowa, Iowa City
R. RHODES TRUSSELL,
Montgomery Watson, Pasadena, California
Staff
STEPHEN D. PARKER, Director
LAURA J. EHLERS, Senior Staff Officer
CHRIS ELFRING, Senior Staff Officer
JEFFREY W. JACOBS, Senior Staff Officer
MARK C. GIBSON, Staff Officer
WILLIAM S. LOGAN, Staff Officer
M. JEANNE AQUILINO, Administrative Associate
PATRICIA A. JONES, Study/Research Associate
ANITA A. HALL, Administrative Assistant
ELLEN A. DE GUZMAN, Senior Project Assistant
ANIKE L. JOHNSON, Project Assistant
COMMISSION ON GEOSCIENCES, ENVIRONMENT, AND RESOURCES
GEORGE M. HORNBERGER, Chair,
University of Virginia, Charlottesville
RICHARD A. CONWAY,
Union Carbide Corporation (Retired), S. Charleston, West Virginia
LYNN GOLDMAN,
Johns Hopkins School of Hygiene and Public Health, Baltimore, Maryland
THOMAS E. GRAEDEL,
Yale University, New Haven, Connecticut
THOMAS J. GRAFF,
Environmental Defense, Oakland, California
EUGENIA KALNAY,
University of Maryland, College Park
DEBRA KNOPMAN,
Progressive Policy Institute, Washington, D.C.
BRAD MOONEY,
J. Brad Mooney Associates, Ltd., Arlington, Virginia
HUGH C. MORRIS,
El Dorado Gold Corporation, Vancouver, British Columbia
H. RONALD PULLIAM,
University of Georgia, Athens
MILTON RUSSELL,
Joint Institute for Energy and Environment and University of Tennessee (Emeritus), Knoxville
ROBERT J. SERAFIN,
National Center for Atmospheric Research, Boulder, Colorado
ANDREW R. SOLOW,
Woods Hole Oceanographic Institution, Woods Hole, Massachusetts
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 and Financial Officer
SANDI FITZPATRICK, Administrative Associate
Preface
Any review of the U.S. Army Corps of Engineers's approach to technical issues and their applications tends to be complicated because of the Corps's size, its lengthy and rich history, its relations with other federal agencies, and controversies that have followed the Corps for decades. This review and study were no different. Our study committee was challenged to analyze the Corps 's risk analysis techniques in its flood damage reduction studies, a challenge that was magnified by the need to understand several related issues. Our committee experts in hydrology, engineering, and statistics found themselves analyzing not only risk analysis applications, but also considering levee certification policy and history, federal flood insurance programs, and U.S. floodplain management strategies. The committee undertook these peripheral investigations partly because of the need to adequately address its statement of task and partly out of intellectual curiosity. In any event, one implicit conclusion of our study is that an appreciation of the Corps 's historical roles in addressing the nation's flood problems is necessary to understand the current issues the Corps faces in engineering and hydrologic applications.
The Corps's relatively new applications of risk analysis represent a significant departure from long-held, traditional approaches to addressing hydrologic, hydraulic, and geotechnical uncertainties. The former approach of adding freeboard to its levees was for several decades a sound strategy for coping with unquantifiable uncertainties. Because of historical momentum, this former approach has left a legacy that is not easily jettisoned. Several Corps of Engineers techniques and policies
were based upon the concept of freeboard, and it will take some time for the agency to fully adjust to the new techniques.
In watching these changes within the agency, our committee gained an appreciation for the dedication of several Corps of Engineers staff members who assisted with this study. Much of the development of the risk analysis techniques has taken place at the Corps's Hydrologic Engineering Center in Davis, California. The committee expresses its gratitude and appreciation to Darryl Davis, the Center's director. Darryl has been a leader in promoting risk analysis applications within the Corps. The committee appreciates Darryl's frankness and cooperation during this study. David Goldman, also of the Hydrologic Engineering Center, has been central to tailoring the risk analysis techniques to Corps applications and deserves major credit for advancing risk analysis within the Corps.
Several other Corps of Engineers staff members shared their knowledge and views with the committee. Earl Eiker and Harry Kitch at Corps Headquarters in Washington, D.C., and David Moser of the Corps's Institute for Water Resources, spoke with the committee at its first meeting in Washington in December 1998. Staff from the Corps's Louisville district office hosted a visit by a committee member in the summer of 1999 and provided information for the committee's Beargrass Creek case study. The committee thanks Neil O'Leary, Richard Pruitt, and Matt Scheuler in the Louisville district office for their assistance.
The committee thanks Joe Countryman of MBK Consultants (Sacramento), Michael Grimm of the Federal Emergency Management Agency (Washington, D.C.), and Doug Plascencia of Kimley-Horn (Phoenix) and member of the Association of State Floodplain Managers—all of whom spoke with the committee at its second meeting in Davis in February 1999. Joe, Mike, and Doug provided compelling remarks that helped the committee consider wider implications of the Corps's use of risk analysis.
Peter Andrysiak, U.S. Army, and Mitchell Laird of the Louisville district also provided significant assistance in acquiring project documents and data.
The committee also thanks Stephen Parker, director of the Water Science and Technology Board (WSTB). Steve followed the progress of this committee closely, and the committee frequently drew upon his knowledge of risk analysis and the Corps of Engineers planning procedures. His experience in managing numerous WSTB reports was useful in helping the committee reach agreement on some key technical issues.
Finally, the entire committee expresses its gratitude to project assistant Ellen de Guzman. Ellen demonstrated superb organizational skills, reviewed and organized several drafts of the committee's report, and also showed a great deal of patience and aplomb in dealing with too many last-minute requests from the chair and study director.
This report has been reviewed by individuals chosen for their diverse perspectives and technical expertise, in accordance with procedures approved by the Report Review Committee of the National Research Council (NRC). 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 contents of the review and draft manuscripts remain confidential to protect the integrity of the deliberative process. We wish to thank the following individuals for their participation in the review of this report:
Paul Barton, U.S. Geological Survey
Leo Beard, Professor Emeritus, University of Texas
Stephen Burgess, University of Washington
John Cassidy, consultant, Concord, California
Susan Cutter, University of South Carolina
Des Hartford, British Columbia Hydro
Debra Knopman, Progressive Policy Institute
Eric Wood, Princeton University
Although the individuals listed above provided many constructive comments and suggestions, responsibility for the final content of this report rests solely with the authoring committee and the NRC.
GREGORY B. BAECHER
Chair
JEFFREY W. JACOBS
Study Director