Levees and the National
Flood Insurance Program

Improving Policies and Practices

Committee on Levees and the National Flood Insurance Program:

Improving Policies and Practices

Water Science and Technology Board

Division on Earth and Life Studies

NATIONAL RESEARCH COUNCIL
OF THE NATIONAL ACADEMIES

THE NATIONAL ACADEMIES PRESS

Washington, D.C.

THE NATIONAL ACADEMIES PRESS    500 Fifth Street, NW    Washington, DC 20001

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 panel responsible for the report were chosen for their special competences and with regard for appropriate balance.

Support for this study was provided by the U.S. Federal Emergency Management Agency under grant contract number HSHQDC-11-D-00009 and task order HSFEHQ-11-J-0001. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the organizations or agencies that provided support for the project.

International Standard Book Number-13: 978-0-309-28290-1
International Standard Book Number-10: 0-309-28290-X
Library of Congress Control Number 2013940694

Cover image courtesy of the U.S. Army Corps of Engineers, Mississippi Valley Division.

THE NATIONAL ACADEMIES

Advisers to the Nation on Science, Engineering, and Medicine

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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. C. D. (Dan) Mote, Jr., is president of the National Academy of Engineering.

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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. Ralph J. Cicerone and Dr. C. D. (Dan) Mote, Jr.,s are chair and vice chair, respectively, of the National Research Council.

COMMITTEE ON LEVEES AND THE NATIONAL FLOOD INSURANCE PROGRAM: IMPROVING POLICIES AND PRACTICES

GERALD E. GALLOWAY, Chair, University of Maryland, College Park

PATRICK L. BROCKETT, University of Texas, Austin

SUSAN L. CUTTER, University of South Carolina, Columbia

DAVID T. FORD, David Ford Consulting Engineers, Sacramento, California

CLIVE Q. GOODWIN, FM Global Insurance Company, Johnston, Rhode Island

KARIN M. JACOBY, Spica Consulting, LLC, Kansas City, Missouri

DAVID I. MAURSTAD, OST Inc., McLean, Virginia

MARTIN W. McCANN, Jack R. Benjamin and Associates, Inc, Menlo Park, California

ANDRE D. McDONALD, Fort Bend Flood Management Association, Sugar Land, Texas

EARTHEA A. NANCE, University of New Orleans, Louisiana

KENNETH W. POTTER, University of Wisconsin, Madison

J. DAVID ROGERS, Missouri University of Science and Technology, Rolla

NRC STAFF

LAURA J. HELSABECK, Senior Program Officer

MICHAEL J. STOEVER, Research Associate

WATER SCIENCE AND TECHNOLOGY BOARD

DONALD I. SIEGEL, Chair, Syracuse University, New York

LISA ALVAREZ-COHEN, University of California, Berkeley

EDWARD J. BOUWER, Johns Hopkins University, Baltimore, Maryland

YU-PING CHIN, Ohio State University, Columbus

M. SIOBHAN FENNESSY, Kenyon College, Gambier, Ohio

BEN GRUMBLES, Clean Water America Alliance, Washington, D.C.

GEORGE R. HALLBERG, The Cadmus Group, Watertown, Massachusetts

KENNETH R. HERD, Southwest Florida Water Management District, Brooksville, Florida

GEORGE M. HORNBERGER, Vanderbilt University, Nashville, Tennessee

CATHERINE L. KLING, Iowa State University, Ames

DEBRA S. KNOPMAN, RAND Corporation, Arlington, Virginia

LARRY LARSON, Association of State Floodplain Managers, Madison, Wisconsin

RITA P. MAGUIRE, Maguire & Pearce PLLC, Phoenix, Arizona

DAVID H. MOREAU, University of North Carolina, Chapel Hill

ROBERT SIMONDS, The Robert Simonds Company, Culver City, California

FRANK H. STILLINGER, Princeton University, Princeton, New Jersey

MARYLYNN V. YATES, University of California, Riverside

JAMES W. ZIGLAR, SR., Van Ness Feldman, Washington, D.C.

STAFF

JEFFREY W. JACOBS, Director

LAURA J. EHLERS, Senior Program Officer

LAURA J. HELSABECK, Senior Program Officer

STEPHANIE E. JOHNSON, Senior Program Officer

M. JEANNE AQUILINO, Financial and Administrative Associate

MICHAEL J. STOEVER, Research Associate

ANITA A. HALL, Senior Program Associate

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Acknowledgment of Reviewers

This report has been reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise, in accordance with procedures approved by the National Research Council’s Report Review Committee. The purpose of this independent review is to provide candid and critical comments that will assist the institution in making its 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 review comments and draft manuscript remain confidential to protect the integrity of the deliberative process. We wish to thank the following individuals for their review of this report:

GREGORY B. BAECHER, University of Maryland

RUDOLPH BONAPARTE, Geosyntec Consultants

MARK BROWNE, University of Wisconsin

MICHAEL K. BUCKLEY, Dewberry

TIMOTHY A. COHN, U.S. Geological Survey

DARRYL W. DAVIS, U.S. Army Corps of Engineers

JEROME B. GILBERT, Consulting Engineer

HOWARD KUNREUTHER, University of Pennsylvania

LARRY LARSON, Association of State Floodplain Managers

LEWIS E. LINK, University of Maryland

JEFFREY F. MOUNT, University of California

TIMOTHY TINKER, Booz Allen Hamilton

Although the reviewers listed above have provided many constructive comments and suggestions, they were not asked to endorse the conclusions or recommendations nor did they see the final draft of the report before its release. The review of this report was overseen by Henry J. Vaux, University of California, and Michael C. Kavanaugh, Geosyntec Consultants. Appointed by the National Research Council, they were responsible for making certain that an independent examination of this report was carried out in accordance with institutional procedures and that all review comments were carefully considered. Responsibility for the final content of this report rests entirely with the authoring committee and the institution.

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Preface

Over the last decades, the United States has seen significant increases in disastrous flooding and rising losses in both human and property damage along rivers and coastlines from extreme storms and hurricane events. Hurricanes Katrina and Sandy will long be remembered for their human toll and economic costs—two of the most destructive natural disasters in U.S. history. These events not only had extensive personal and economic consequences for those directly and indirectly affected, but also threaten the nation’s long-standing efforts to reduce the impacts of such events. Nations around the world face similar challenges.

Many of the damages that have resulted from flooding have involved either the failure of levees and related structures to withstand flood and hurricane stress, the overtopping of these levees once their design height was exceeded, or both. The majority of losses in New Orleans during Hurricane Katrina in 2005 stemmed from levee failures and overtopping. Many levees along the Missouri and Upper Mississippi rivers and their tributaries that were hit by historic floods in 2008 and 2011 experienced overtopping and failure. In 2007, the U.S. Army Corps of Engineers (USACE) reported that 122 levees under its oversight were at risk of failing, and later that year, the Congress passed the National Levee Safety Act. In 2009, a National Committee on Levee Safety, formed by the Act, stressed the threatening nature of this situation and indicated that a significant number of levees across the country are not well maintained and do not meet the standards required by the National Flood Insurance Program (NFIP), USACE levee programs, or accepted engineering practices. Also in 2009, the Infrastructure Report Card of the American Society of Civil Engineers assigned a grade of “D–” to the nation’s levees and cited a maintenance backlog of nearly $50 billion.

The National Research Council (NRC) and its Water Science and Technology Board were asked by the Federal Emergency Management Agency (FEMA) to examine the manner in which levees are addressed in the NFIP and to provide advice as to what actions might be taken to improve program efficiency and effectiveness. The NRC established the Committee on Levees and the National Flood Insurance Program: Improving Policies and Practices to carry out this task. Committee members spent 16 months reviewing the program’s history, examining numerous documents and reports, receiving briefings from relevant stakeholders including FEMA and other government agency officials. It held 12 virtual and in-person meetings in Washington, D.C., and in the Houston Texas, Sacramento, California, and St. Louis, Missouri areas to meet with those who supervise, operate, and maintain or are affected by levees.

For the most of the last three centuries, the nation has relied heavily on using structural means such as levees and dams to deal with flooding. Levees that are properly constructed, maintained, and upgraded when necessary

have prevented inundation of major communities in the face of major flood events and have helped avert billions of dollars in damages. The performance of the levees on the Lower Mississippi River during the record 2011 floods provided strong testimony to the value of levees.

Beginning with studies in the 1940s and 1950s, including work from the late geographer Gilbert F. White, it was increasingly appreciated that a comprehensive approach to managing flooding that complemented levees and dams with nonstructural measures such as land-use planning, zoning, floodproofing, and flood insurance was needed. Over the last two decades of the 20th century, the comprehensive approach advocated by White began a transition to the concept of flood risk management that is founded on the understanding that no matter what actions are taken to reduce structural system risks, the residual risk of structural failure will always remain and that management strategies will take advantage of a broad portfolio of mitigation measures. This approach has been increasingly adopted around the globe and forms the basis of the European Union’s 2007 Flood Directive. This report focuses on technical and programmatic aspects of the NFIP’s treatment of levees and leveed areas that exist within the context of flood risk management and recognizing that NFIP-related levees represent only 5 to 10 percent of the nation’s levees.

This report does not address standards for levels of flood protection. The one percent annual chance (100-year) flood originally was used by USACE and the Tennessee Valley Authority as one measure of explaining flood threat. This recurrence interval was later legislated by the Congress to designate areas that would be regulated in the NFIP. Over time, however, this standard has frequently been presumed also to be a flood safety standard for floodplain occupancy. Although an important topic, the committee concluded that it would be outside the charge to recommend a safety standard for levees in heavily urbanized area, but did note that many other expert reports have suggested that the one percent annual chance flood standard is inadequate for large urban areas. For example, a 2009 report from a committee of the NRC recommended that the protection system for the City of New Orleans be designed for a hurricane storm surge event with an expected recurrence interval of 400 to 1,000 years. The committee also discussed the natural and beneficial functions of floodplains and the impacts that activities in the floodplain have on these functions, but determined that this topic also was outside the charge.

Finally, the committee owes much to the untiring efforts of our NRC Study Director, Dr. Laura J. Helsabeck, whose intellectual acumen, organizational skills, writing abilities, collaborative temperament, and exceptionally long hours brought the report together and kept us focused on our mission. She was ably assisted by our research associate, Michael Stoever, who deftly handled research and logistics activities for the committee over its term. Dr. Jeff Jacobs, the Director of the Water Science and Technology Board, provided much appreciated oversight of and support to the committee.

Gerald E. Galloway, Chair
Committee on Levees and the
National Flood Insurance Program:
Improving Policies and Practices

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Contents

Acronyms and Initialisms