Mapping the Zone: Improving Flood Map Accuracy

137 Pages·2009·17.11 MB·English

by  Mapping Science Committee

Mapping the Zone: Improving Flood Map Accuracy
Mapping
the Zone

ImprovIng Flood map accuracy
Committee on FEMA Flood Maps
Board on Earth Sciences and Resources/Mapping Science Committee
Water Science and Technology Board
Copyright © National Academy of Sciences. All rights reserved.
Mapping the Zone: Improving Flood Map Accuracy
The NaTioNal academies Press 500 Fifth street, N.W. 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 committee responsible
for the report were chosen for their special competences and with regard for appropriate balance.
This study was supported by the Federal Emergency Management Agency under Award No. HSFE03-06-C-
0030 and by the National Oceanic and Atmospheric Administration under Award No. DG133R07SE2691.
Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s)
and do not necessarily reflect the view of the organizations or agencies that provided support for this project.
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International Standard Book Number-10: 0-309-13057-3 (Book)
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Cover: June 2008 flooding in Cedar Rapids, Iowa (foreground), and a portion of the FEMA Flood Insurance
Rate Map in the same region (background). This part of the downtown is within the Special Flood Hazard
Area (zone A), which is subject to a 1 percent or greater chance of flooding in any given year. Photograph
courtesy of Stephen Mally. Used with permission. Map extract from FEMA’s Map Service Center. Cover
design by Van Nguyen.
Copyright 2009 by the National Academy of Sciences. All rights reserved.
Printed in the United States of America
Copyright © National Academy of Sciences. All rights reserved.
Mapping the Zone: Improving Flood Map Accuracy
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Copyright © National Academy of Sciences. All rights reserved.
Mapping the Zone: Improving Flood Map Accuracy
Copyright © National Academy of Sciences. All rights reserved.
Mapping the Zone: Improving Flood Map Accuracy
COMMITTEE ON FEMA FLOOD MAPS
DAVID R. MAIDMENT, Chair, University of Texas, Austin
DAVID S. BROOKSHIRE, University of New Mexico, Albuquerque
J. WILLIAM BROWN, City of Greenville, South Carolina
JOHN DORMAN, State of North Carolina, Raleigh
GERALD E. GALLOWAY, University of Maryland, College Park
BISHER IMAM, University of California, Irvine
WENDY LATHROP, Cadastral Consulting, LLC, Bala Cynwyd, Pennsylvania
DAVID MAUNE, Dewberry, Fairfax, Virginia
BURRELL E. MONTZ, Binghamton University, New York
SPENCER ROGERS, North Carolina Sea Grant, Wilmington
KAREN L. SCHUCKMAN, Pennsylvania State University, University Park
Y. PETER SHENG, University of Florida, Gainesville
JUAN B. VALDES, University of Arizona, Tucson
National academies staff
ANNE M. LINN, Study Director, Board on Earth Sciences and Resources
LAUREN E. ALEXANDER, Senior Program Officer, Water Science and Technology
Board, and Director, Disasters Roundtable
JARED P. ENO, Research Associate, Board on Earth Sciences and Resources
TONYA E. FONG YEE, Senior Program Assistant, Board on Earth Sciences and
Resources
v
Copyright © National Academy of Sciences. All rights reserved.
Mapping the Zone: Improving Flood Map Accuracy
MAPPING SCIENCE COMMITTEE
KEITH C. CLARKE, Chair, University of California, Santa Barbara
ROBERT P. DENARO, NAVTEQ Corporation, Chicago, Illinois
GEORGE F. HEPNER, University of Utah, Salt Lake City
JOHN R. JENSEN, University of South Carolina, Columbia
NINA S.-N. LAM, Louisiana State University, Baton Rouge
LEWIS A. LAPINE, South Carolina Geodetic Survey, Columbia
MARY L. LARSGAARD, University of California, Santa Barbara
XAVIER R. LOPEZ, Oracle Corporation, Nashua, New Hampshire
ROBERT B. McMASTER, University of Minnesota, Minneapolis
SHASHI SHEKHAR, University of Minnesota, Minneapolis
EUGENE TROBIA, Arizona State Land Department, Phoenix
National academies staff
ANNE M. LINN, Senior Program Officer
JARED P. ENO, Research Associate
vi
Copyright © National Academy of Sciences. All rights reserved.
Mapping the Zone: Improving Flood Map Accuracy
BOARD ON EARTH SCIENCES AND RESOURCES
GEORGE M. HORNBERGER, Chair, Vanderbilt University, Nashville
GREGORY B. BAECHER, University of Maryland, College Park
KEITH C. CLARKE, University of California, Santa Barbara
DAVID J. COWEN, University of South Carolina, Columbia
WILLIAM E. DIETRICH, University of California, Berkeley
ROGER M. DOWNS, The Pennsylvania State University, University Park
JEFF DOZIER, University of California, Santa Barbara
KATHERINE H. FREEMAN, The Pennsylvania State University, University Park
RUSSELL J. HEMLEY, Carnegie Institution of Washington, Washington, D.C.
MURRAY W. HITZMAN, Colorado School of Mines, Golden
LOUISE H. KELLOGG, University of California, Davis
CLAUDIA INÉS MORA, Los Alamos National Laboratory, New Mexico
BRIJ M. MOUDGIL, University of Florida, Gainesville
V. RAMA MURTHY, University of Minnesota (retired), Minneapolis
CLAYTON R. NICHOLS, Idaho National Engineering and Environmental
Laboratory (retired), Sandpoint
RAYMOND A. PRICE, Queen’s University, Kingston, Ontario, Canada
BARBARA A. ROMANOWICZ, University of California, Berkeley
JOAQUIN RUIZ, University of Arizona, Tucson
WILLIAM W. SHILTS, Illinois State Geological Survey, Champaign
RUSSELL STANDS-OVER-BULL, Anadarko Petroleum Corporation, Billings,
Montana
TERRY C. WALLACE, JR., Los Alamos National Laboratory, New Mexico
HERMAN B. ZIMMERMAN, National Science Foundation (retired), Portland,
Oregon
National research council staff
ANTHONY R. dE SOUZA, Director
ELIZABETH A. EIDE, Senior Program Officer
DAVID A. FEARY, Senior Program Officer
ANNE M. LINN, Senior Program Officer
SAMMANTHA L. MAGSINO, Program Officer
CAETLIN M. OFIESH, Associate Program Officer
JENNIFER T. ESTEP, Financial and Administrative Associate
JARED P. ENO, Research Associate
NICHOLAS D. ROGERS, Research Associate
COURTNEY R. GIBBS, Program Associate
TONYA E. FONG YEE, Senior Program Assistant
ERIC J. EDKIN, Program Asssistant
vii
Copyright © National Academy of Sciences. All rights reserved.
Mapping the Zone: Improving Flood Map Accuracy
WATER SCIENCE AND TECHNOLOGY BOARD
CLAIRE WELTY, Chair, University of Maryland, Baltimore County
JOAN G. EHRENFELD, Rutgers University, New Brunswick, New Jersey
GERALD E. GALLOWAY, University of Maryland, College Park
SIMON GONZALEZ, National Autonomous University of Mexico
CHARLES N. HAAS, Drexel University, Philadelphia, Pennsylvania
KENNETH R. HERD, Southwest Florida Water Management District, Brooksville
JAMES M. HUGHES, Emory University, Atlanta, Georgia
THEODORE L. HULLAR, Private Consultant, Tucson, Arizona
KIMBERLY L. JONES, Howard University, Washington, DC
G. TRACY MEHAN III, The Cadmus Group, Inc., Arlington, Virginia
DAVID H. MOREAU, University of North Carolina, Chapel Hill
THOMAS D. O’ROURKE, Cornell University, Ithaca, New York
DONALD I. SIEGEL, Syracuse University, New York
SOROOSH SOROOSHIAN, University of California, Irvine
HAME M. WATT, Independent Consultant, Washington, DC
JAMES L. WESCOAT, JR., University of Illinois, Urbana-Champaign
National research council staff
STEPHEN D. PARKER, Director
JEFFREY W. JACOBS, Scholar
LAURA J. EHLERS, Senior Staff Officer
STEPHANIE E. JOHNSON, Senior Staff Officer
LAURA E. HELSABECK, Associate Staff Officer
M. JEANNE AQUILINO, Financial and Administrative Associate
ELLEN A. DE GUZMAN, Research Associate
ANITA A. HALL, Senior Program Associate
MICHAEL J. STOEVER, Senior Program Assistant
STEPHEN T. RUSSELL, Project Assistant
viii
Copyright © National Academy of Sciences. All rights reserved.
Mapping the Zone: Improving Flood Map Accuracy
Preface
Federal Emergency Management Agency the committee conducted original analyses of variables
(FEMA) Flood Insurance Rate Maps portray that influence flood map accuracy, such as elevation
flood hazard areas, and they form the basis and flood flow.
for setting flood insurance premiums and regulating The committee would like to thank the indi-
development in the floodplain. As such, they are an viduals who briefed the committee or provided data,
important tool for individuals, businesses, commu- figures, or other input: Ken Ashe, Glenn Austin, Jerad
nities, and government agencies to understand and Bales, Julio Cañon, Andy Carter, Tim Cohn, Todd
deal with flood hazard and flood risk. Improving map Davison, David Divoky, Mary Erickson, Dean Gesch,
accuracy is therefore not an academic question—better Mike Godesky, Susan Greenlee, Ruth Haberman,
maps help everyone. Eric Halpin, Victor Hom, Marti Ikehara, Doo Sun
This study was requested by managers of FEMA’s Kang, Larry Larson, Kevin Long, Doug Marcy, Kate
Risk Analysis Division and the National Oceanic and Marney, Robert Mason, Gordon McClung, Sally
Atmospheric Administration’s (NOAA’s) Coastal Ser- McConkey, Venkatesh Merwade, Mike Moya, Jim
vices Center, supported by NOAA’s National Weather Nelson, Rick Neuherz, Edward Pasterick, Kernell
Service, National Geodetic Survey, and Coast Survey Ries, Dan Roman, Paul Rooney, Rick Sacbibit, Brett
Development Laboratory. The Committee on FEMA Sanders, Eric Tate, Ronnie Taylor, Patty Templeton-
Flood Maps was established to examine the factors Jones, Gary Thompson, D. Phil Turnipseed, Gordon
that affect flood map accuracy, assess the economic Wells, Bruce Worstell, and Dave Zilkoski. Special
benefits of more accurate flood maps, and identify ways thanks go to Thomas Langan, Stephanie Dunham,
to improve flood mapping, communication, and man- and Jerry Sparks, who carried out extensive hydrologic
agement of flood-related data. Committee members and economic case studies for the committee. Their
included academics and practitioners who collectively efforts greatly expanded the pool of data from which
possessed expertise covering inland and coastal flood to draw conclusions about improving the accuracy of
modeling and mapping, geospatial data management, flood maps. The committee also thanks the National
flood hazard assessment, and economic and policy Academies staff who worked on this report: Lauren
implications of flood map accuracy. Information on Alexander Augustine, Tonya Fong Yee, Jared Eno, and
these topics was gathered from the literature, the Asso- particularly Anne Linn, the study director, who expertly
ciation of State Floodplain Managers, discussions with guided the committee’s activities and contributed
colleagues, and briefings at five committee meetings significantly to synthesizing our results.
held between June 2007 and April 2008. In addition
to these traditional means of gathering information, David R. Maidment
Chair
ix
Copyright © National Academy of Sciences. All rights reserved.