--an invited comment
Not all hazard-generating processes are independent of time or human influence. Even if hazards did not vary with time, the associated risks would inevitably increase since populations and hazard-exposed assets increase with time. Yet, do we allow for these sometimes human-induced factors in our risk mitigation policies and actions?
Not as much as we should. Quantitative probabilistic hazard assessment is generally based on the record of past hazardous events and used to account for present and near-future hazards. However, the catalog of hazardous events is not always the only input to the assessment. Sometimes, generalized models based on the historic record that account for the physical processes in the region are used.
To be maximally effective, the latest scientific knowledge must be applied when estimating future hazards and risks. Take, for instance, National Flood Insurance Program (NFIP) maps. For most localities, flood zones were mapped many decades ago. Since then, in many of the most rapidly developing regions of the U.S., land-use patterns have drastically changed, altering the ability of the land to absorb high amounts of precipitation and to extend the duration of run-off in rivers and floodplains. Flooding beyond designated flood zones appears to be increasing, although systematic surveys to confirm this notion are generally lacking. Hence, flood-zone mapping does not depict the present state of the hazard, nor have we evaluated other increasing risk exposures threatening many parts of the U.S.
The Metropolitan East Coast (MEC) region provides an example of an area in which future risks in relation to storm surge floods need to be evaluated. The MEC is composed of 31 counties in southern New York, northern New Jersey, and southwestern Connecticut, with New York City as its economic hub. The region has a population of almost 20 million, built assets of $2 trillion--almost half of which are infrastructure (roads, bridges, airports, harbors, railroads, utilities, and communication facilities). The remaining assets include residential, commercial, and public buildings and their contents. The region generates an annual economic output of just below $1 trillion.
Many of the region's built assets are close to the waterfront and exposed to coastal storm surges. Many transportation systems have lowest points of elevation of only six to 20 feet above NGVD,1 exposing them to flooding and jeopardizing their operations.
The MEC is one of more than a dozen regions across the U.S. participating in the U.S. Global Change Research Program's Assessment of Regional and National Impacts of Global Climate Change, and is the only megalopolis being studied. The region is exposed to an increasing frequency of coastal storm surge floods, a good portion of which can be attributed to global warming and subsequent sea level rise.
Indeed, different climate models adopted by the U.S. Global Climate Change Program predict sea level increases of one to three feet by the year 2100. These estimates take into account local land subsidence, melting of alpine glaciers and icecaps, and the thermal expansion of warming oceans.
Analyses of past storm surges caused by hurricanes and "nor'easter" winter storms (about a dozen in the last 100 to 200 years) indicate that flooding at the southern tip of Manhattan in excess of 10 feet above NGVD occurs about once every 50 years. Lesser storm surge floods occur more frequently, higher surges less frequently. Some New York City subway and Hudson and East River tunnel entrances, La Guardia Airport, some harbor facilities, and some highways near the waterfront have been flooded more than once since they were built over the last 50 to 100 years.
The U.S. Army Corps of Engineers, together with the National Weather Service, used the Sea and Lake Overland Surge Height (SLOSH) model to calculate worst-case storm-track surges in New York Harbor and adjacent coastal regions. Worst-case hurricane tracks make landfall south of New York City, in New Jersey. The model calculates worst-
case surge heights near the Manhattan entrance of the Lincoln Tunnel as 7.5 feet above NGVD for a Saffir-Simpson category 1 hurricane; 17.2 feet for a category 2; 20.5 feet for a category 3; and 30.8 feet for a category 4 (should one ever occur at this latitude). According to the models, a worst-case-track hurricane above category 2 will cause extensive flooding that could split lower Manhattan along Canal Street into two islands.
How will the modest one to three feet of sea level rise change the frequency of storm surge heights? The surprising answer is that storm surges less than 20 feet in height may occur between two and 10 times more often, with an average of three times more often, by the year 2100. Currently, only rough estimates can be made of economic losses due to surges at current sea levels or at the raised sea levels in the year 2100. (Systematic loss estimates using the Federal Emergency Management Agency's HAZUS [hazard mapping] programs are not yet available for flood and wind [in contrast to earthquakes].) The table below summarizes initial findings.
Even without accounting for an increase in assets and their valuations, losses from these coastal storms and floods will increase as the hazard increases. Expected annualized losses from coastal storms, on the order of a billion dollars per year, could be absorbed by the MEC economy. However, actual losses do not occur neatly in regular annual doses. Rather, they occur because of infrequent and irregular extreme events that can cause hundreds of billions of dollars in damage at one time. Insurers, policy holders, and those without insurance would be stretched to the brink. Indeed, if these and smaller events become two to 10 times more frequent, mitigating actions will have to be taken, and taken fast. Without them, the region will experience increasing losses and be forced to bear the rising costs of recovery and remediation.
|Estimates for Surge Heights and Losses in the MEC and Their Recurrence Periods for the Years 2000 and 2100|
|Equivalent Saffir-Simpson Category*||Surge Height above NGVD (in feet)||Estimated Total Loss ($ billion)**||Average Recurrence Period||Annualized Losses***|
($ million per year)
|Year 2000||Year 2100|
|Extratropical Storm||8||1||20||6||50 - 170|
|1||10||5||50||15||100 - 330|
|2||11||10||100||30||100 - 300|
|3||13||50||500||150||100 - 300|
|3-4||14||100||1,000||300||100 - 300|
|4||16||>250||2,500||800||100 - 300|
|All Categories||Approximately 500 - 1,500|
The MEC is already revamping its basic infrastructure at a cost of about a billion dollars per year. The most cost-effective way to protect this investment against future storm surge losses is to adopt and comply with technical standards during rebuilding that reflect increased flood potentials. A coherent policy, based on sound technical input, is needed. Although some uncertainties about the increased hazards and loss potentials exist (and will persist even after future detailed technical and scientific studies), they must not be used as excuses for inaction. Losses will accelerate just from the sheer growth of built and newly exposed assets. If billions of dollars are invested in new structures without accounting for sea level rise, tens or hundreds of billions of dollars in future losses will occur.
The best mitigation is to avoid placing new or refurbished structures and assets at low elevations. This requires an innovative land-use plan and tough zoning enforcement, and would work best if combined with new national engineering codes that place all critical components at sufficiently high elevations. Such mitigation could be effectively achieved by a Voluntary National Model Code. The NFIP would have a new role to play in remapping coastal and other high-risk flood zones. Congress should provide the additional resources for the NFIP or create a successor program to deal with this major undertaking. Current haphazard updating of existing coastal and other flood-zone maps will not do.
The sea level rise that New York City and the MEC are about to face will affect all coastal megacities and shore-bound populations around the U.S. and throughout the world. New York City and its surrounding region could muster the financial and intellectual resources, perhaps even the political wit and will, to set an example for dealing with this fundamental issue. Climate-change-induced sea level rise is forcing us into a race against time that we must face, finance, and win.
Klaus H. Jacob, Lamont-Doherty Earth Observatory, Columbia University
Of course, many volumes have been written about the possible implications of climate change and global warming for sea level rise and natural hazards. Below are some recent additions to this anthology.
Sea-Level Rise and Global Climate Change: A Review of Impacts to U.S. Coasts. James E. Neumann, Gary Yohe, and
Robert Nicholls. 2000. 44 pp. The complete report is available at the Pew Center on Global Climate Change Web site:
http://www.pewclimate.org/projects/env_sealevel.html. For further information, contact the Pew Center on Global Climate
Change, 2101 Wilson Boulevard, Suite 550, Arlington, VA 22201; (703) 516-4146.
Sections include a review of factors affecting the vulnerability of the U.S. coastal zone, a summary of key concepts in the science of sea-level rise assessment, a description of physical impacts of climate change on coastal resources, a discussion of human response and adaptation to coastal threats, a review of economic impacts of sea-level rise on coastal properties and wetlands, and conclusions.
El Niño 1997-1998: The Climate Event of the Century. Stanley A. Changnon, Editor. 2000. 232 pp. $29.95, paper;
$60.00, clothbound. To purchase a copy, contact Oxford University Press Order Department, 2001 Evans Road, Cary, NC
27513; WWW: http://www.oup.com.
This volume assembles the perspectives of experts in science, public policy, and the media regarding El Niño. Topics include causes, predictions, El Niño as a weather metaphor for global warming, scientific issues, uses and benefits of El Niño forecasts, and implications for improved forecasts and climate services to the U.S.
El Niño and La Niña: Tracing the Dance of Ocean and Atmosphere. 2000. 8 pp. Free. Available via the World Wide
This brochure chronicles decades of basic scientific research leading to greater understanding of the relationship between earth's oceans and the climatological phenomena of El Niño and La Niña.
Global Environmental Change: Research Pathways for the Next Decade. 2000. 616 pp. $89.95. Copies can be ordered
from the National Academy Press, 2101 Constitution Avenue, N.W., Lockbox 285, Washington, DC 20055; (800) 624-6242.
To place an order on-line that provides a 20% discount or to view the complete text free, see http://www.nap.edu.
In order to adapt to global climate change, we must understand the processes that control changes in climate and the composition of the atmosphere, as well as how ecosystems and humans interact with these changes. This volume encourages a renewed commitment to understanding global climate change and sets a direction for research in the decade ahead. Through case studies, the book explores the lessons of the past 20 years and poses the scientific questions that remain.
Assessing Regional Impacts of Climate Change, El Niño, La Niña, and More: Extreme Weather, Climate Variability,
and the Mississippi Basin. Weather Backgrounder Series. 1998. 20 pp. Free. Available on-line:
http://www.nsc.org/ehc/jrn/weather/weath2.htm. For further information, contact the National Safety Council's
Environmental Health Center, 1025 Connecticut Avenue, N.W., Suite 1200, Washington, DC 20036; (202) 293-2270; e-mail: email@example.com; WWW: http://www.nsc.org/ehc.htm.
This document examines flood and drought in the Mississippi Basin, describes weather extremes and climate variability, and explains how El Niño and La Niña could affect the Midwest as well as what would happen if global warming should occur. It also describes possible regional vulnerabilities, including flooding, transportation disruption, ecological disruption, agricultural impacts, and changes in quality of municipal water supply and sewage treatment. Finally, it lists several story ideas for journalists that relate to Midwestern climate vulnerability.
The Natural Hazards Center has published two new Quick Response reports on the Web. Conducted days to weeks after disasters, these studies are intended to reveal information about immediate effects and response. They are disseminated via the Internet by the center as quickly as possible when they are received.
• QR126: Hurricane Floyd Flood Mapping Integrating Landsat 7 TM Satellite Imagery and DEM Data, by Jeffrey D. Colby, Yong Wang, and Karen Mulcahy, East Carolina University.
The authors introduce this report by stating, "Capturing the extent of flooding during an extreme event in an efficient manner is essential for response, recovery, and mitigation activities. An efficient and economical method for mapping flood extent in a coastal floodplain is described in this paper. The method was based on [satellite] images (acquired before and during the flood event) [integrated with] digital elevation model (DEM) data . . . The method proved to be reliable and could be applied quickly using data that are relatively inexpensive, easy to obtain, and easy to analyze."
• QR127: Hurricane Georges: A Multinational Study Examining Preparedness, Resource Loss, and Psychological Distress in the U.S. Virgin Islands, Puerto Rico, Dominican Republic, and the United States, by David N. Sattler and Charles F. Kaiser, College of Charleston.
This study examines preparation by and psychological functioning of victims before and after Hurricane Georges. Four to five weeks following the event, the researchers surveyed almost 700 individuals who weathered the hurricane. They found that in all locations, resource loss was of substantial importance among variables that predicted psychological distress. In addition, storm strength and location accounted for a significant portion of psychological distress variance. The authors go on to discuss the implications of their findings for mitigating psychological distress due to disasters as well as other problems in human disaster response.
A complete list of Quick Response reports is posted at http://www.colorado.edu/hazards/qr/qr.html. Printed copies can be purchased for $5.00 each, plus shipping charges ($4.00 for surface mail to any destination; and $9.00 for international air printed matter). Orders should be directed to the Publications Clerk, Natural Hazards Research and Applications Information Center, Campus Box 482, University of Colorado, Boulder, CO 80309-0482; (303) 492-6819; fax: (303) 492-2151 ; e-mail: firstname.lastname@example.org. Prepayment is required, and checks should be payable to the University of Colorado.
In the previous Observer (Vol. XXIV, No. 5, p. 4), we announced the publication (in printed form) of the Hazard Center's Special Publication 36--The Marginalization of Disaster Response Institutions: The 1997-1998 El Niño Experience in Peru, Bolivia, and Ecuador, by Richard Olson and friends. That paper examines governmental response to the 1997-98 El Niño and concludes that national civil defense organizations in the respective countries--the organizations nominally responsible for managing such emergencies--were quickly shouldered aside when the event became national and international news, and thus a political issue. New, temporary governmental organizations were created to deal with the consequences of the El Niño, and the result was a poorly designed and poorly implemented response. The authors recommend how standing civil defense agencies can better prepare for such events.
The Marginalization of Disaster Response Institutions is now available from the Natural Hazards Center Web site: http://www.colorado.edu/hazards/sp/sp.html. It can be viewed on-line or downloaded in Microsoft Word97 or PDF format. A Spanish version is also available in print or on-line from the Regional Disaster Information Center for Latin America and the Caribbean (CRID): http://www.crid.or.cr, or http://www.crid.or.cr/crid/ENG/NEWS/not7.htm.
Printed copies of The Marginalization of Disaster Response Institutions (SP36, 44 pp.) remain available and can be purchased for $10.00, plus shipping ($5.00 for the U.S., Canada, and Mexico; $8.00 for international mail beyond North America). Orders should be directed to the Publications Clerk, Natural Hazards Research and Applications Information Center, Campus Box 482, University of Colorado, Boulder, CO 80309-0482; (303) 492-6819; fax: (303) 492-2151; e-mail: email@example.com. Prepayment is required. Checks should be payable to the University of Colorado. Visa, Master Card, American Express, and Diners Club cards are also accepted.
A little foresight can go a long way when it comes to reducing the impacts of natural disasters. In an effort to lessen the destructive powers of floods in the U.S., floodplain managers recently met to discuss techniques for anticipating and responding to the next great deluge. The latest publication from the Natural Hazards Center, Planning Ahead: Reducing Flood Losses in the 21st Century, contains technical papers presented at that meeting, the 23rd Annual Conference of the Association of State Floodplain Managers (ASFPM), held in May 1999 in Portland, Oregon.
Topics include local projects and programs for planning, mitigation, acquisition, and recovery; watershed management; protecting and restoring natural and cultural resources in floodplains; community assistance for the National Flood Insurance Program; stormwater management; hydrological forecasting; flood modeling; hazard mapping; special flood-related hazards; international approaches to floodplain management; flood insurance; and federal programs, policies, and initiatives.
Copies of Planning Ahead (Special Publication #37, 295 pp., $20.00, plus $6.00 shipping) can be ordered from the Publications Clerk, Natural Hazards Research and Applications Information Center, Campus Box 482, University of Colorado, Boulder, CO 80309-0482; (303) 492-6819; fax: (303) 492-2151; e-mail: firstname.lastname@example.org; http://www.colorado.edu/hazards. All orders mus t be prepaid. Visa, MasterCard, American Express, and Diners Club cards are accepted.
North Carolina's ban on seawalls to protect its beaches was recently upheld in court after being challenged by a group of homeowners trying to defend their $22 million resort property from destruction by ocean tides. According to the North Carolina Division of Coastal Management, the ban was instituted in response to research demonstrating that hard structures on beachfronts caused the demise of sandy beaches.
In the late 1970s, the North Carolina Coastal Resources Commission, which is the policy making authority for the coastal program, prohibited the use of hard erosion control structures to protect new buildings. In 1985, the commission revised the rule to prohibit such structures for protection of any building, unless it is historic and cannot be relocated, or to protect a waterway for navigation purposes.
When the nine-story Shell Island Resort was built in the 1980s on Wrightsville Beach, its developers signed permits acknowledging they were building in an erosion-prone area, then sold individual condominium units to the public. In 1996, when a nearby inlet had moved to within 200 feet of the resort, homeowners asked for permission to build a steel seawall, and the commission denied their request. Shell Island filed suit in 1998 against the commission, challenging the hard structure rule and arguing that the map used to base issuance of the original building permit underestimated the hazard area of the inlet as well as the degree to which it would migrate. The suit further asserted that, because of these conditions, the state should have never issued a building permit and should now allow the owners of the resort to build a seawall to counteract the erosion. The North Carolina Court of Appeals upheld the commission and the state, ruling that the state did not "take the homeowners property and that "no property owner has the right to construct an erosion control structure on state-owned submerged lands."
For more information about North Carolina's ban on seawalls or the Shell Island Resort Case, contact Donna Moffitt: (919) 733-2293; e-mail: email@example.com. The NOAA Coastal Services Center has an article on its Web site describing the decision, as well as a link to the complete text of the decision. To view, access: http://www.csc.noaa.gov/newsletter/2000/02/nc.html.
In the May 1999 Observer (Vol. XXIII, No. 5, p. 5), we introduced a new initiative--then called the Mid-America Partnership (MAP)--established by representatives of several public and pr ivate central United States organizations. The partnership's goal was to link these groups so that they might help one another in dealing with hazards (particularly earthquakes) affecting the region.
Since then, MAP has been renamed CUSP--the Central United States Partnership. The partnership's goals have been refined, and it is now developing a long-term strategic plan to reduce the risk posed by damaging earthquakes in the central U.S. Member agencies intend to launch a cooperative effort to enlighten residents and policymakers in the region regarding the need to prepare for and mitigate the consequences of earthquakes. CUSP core organizations include the Central U.S. Earthquake Consortium, Association of CUSEC State Geologists, Institute for Business and Home Safety, Mid America Earthquake Center, Federal Emergency Management Agency, and U.S. Geological Survey. The group also involves numerous other partner organizations from the region, and more will be added as plans and programs are defined.
One current goal is to develop a regional seismic advisory council to advise the various partners on directions they should take in order to best coordinate their strengths.
An initial meeting of CUSP was held in July 1999 and a second meeting May 23-24 of this year to refine the long-term plan and define partner expectations around three key issues: living with earthquakes, building for earthquakes, and learning from earthquakes. For more information about CUSP, contact CUSEC, 2630 East Holmes Road, Memphis, TN 38118-8001; (901) 544-3570; fax: (901) 544-0544; e-mail: firstname.lastname@example.org.
In January 2000, Virginia Polytechnic Institute and State University (Virginia Tech) announced the creation of the Earthquake Engineering Center for the Southeastern United States (ECSUS). Those affiliated with the center possess expertise in geotechnical and structural engineering, earthquake seismology, strong ground-motion modeling, seismic hazard assessment, geographic information systems application, and earthquake response planning and mitigation.
The primary roles of ECSUS are to:
For more information about ECSUS, contact the directors, Martin Chapman and James Martin, Department of Civil and Environmental Engineering, 200 Patton Hall, Virginia Tech, Blacksburg, VA 24061; (540) 231-6635; fax: (540) 231-7532; WWW: http://ecsus.ce.vt.edu.
Astute management of limited water resources in the Western U.S. is more important than ever. New tools available to resource and flood managers include climate forecasts that predict above or below normal precipitation and temperature up to a year in advance. Predictions of the 1997-98 El Niño event and its potentially damaging impacts greatly increased the visibility of these forecasts and have left many wondering how best to take advantage of this new technology.
To find out which forecasts agencies access, how they are interpreted, and how they are used, we conducted in-depth interviews with water suppliers, flood control districts, and emergency managers in Arizona. We asked agencies to discuss their experiences with the forecasts, suggest improvements to them, and discuss some of the barriers that prevent agencies from responding to forecasts effectively. The intent of this article is to provide practical advice to emergency managers who are considering incor-porating climate forecasts into their operations.
El Niño refers to the appearance of anomalously warm waters along the equator from the coast of Peru nearly to Indonesia. La Niña is the appearance of anomalously cold waters; collectively, they are known as El Niño Southern Oscillation (ENSO) events. These events reappear every two to seven years and can last for one or more years. El Niño effects in th e U.S. are strongest in winter, particularly in the Pacific Northwest (dry), Florida (wet), and in the Southwest (wet); La Niña has opposite impacts.
Prior to 1997-98, the 1982-83 El Niño was the strongest event in modern history, during which the Southwest experienced unprecedented flood damage. Hence, many agencies paid heed when forecasts indicated the 1997-98 El Niño would be as strong or stronger than the prior event and that Arizona was in store for a wet winter. Media coverage was pervasive, especially in September 1997 when Hurricane Nora threatened the Southwest. Although hurricanes rarely strike this region, their probability is higher in El Niño years. Early forecasts placed Nora on a track toward the metropolitan centers of Arizona--Phoenix and Tucson-- although the observed track was over a hundred miles to the west. While little rain fell in urban regions, 24-hour rainfall records (approximately one foot) were broken west of Phoenix, two towns were flooded, and crop losses reached $300 million. As predicted, the 1997-98 winter was wetter than normal, although ultimately only Hurricane Nora produced floods. Winter precipitation was steady and produced elevated streamflows during winter and spring 1998, without significant flooding.
Several unprecedented water management actions were taken in Arizona in anticipation of El Niño. The major water supplier for Phoenix, the Salt River Project (SRP), released 41,000 acre-feet of water from Verde River reservoirs in anticipation of elevated streamflow. This water replaced pumped groundwater and the resulting reservoir storage space reduced downstream flood risks. SRP faced losses of $5-$6 million if the forecasts were wrong. In addition, various emergency management agencies sponsored interagency briefings, reviewed flood response plans, identified hazards in the field, prioritized mitigation opportunities, and provided information about flood insurance, among other activities. One flood control district's in-house research revealed that floods during El Niño tend to occur on large rivers. Subsequently, the district shifted their annual flood training to involve multiple agencies and focus on large river floods instead of flash floods in usually dry washes. However, a surprising number of agencies were not able to respond to the forecasts and engage in serious preparations for a wet winter.
Based on the Arizona experience during the 1997-98 El Niño, there appear to be four major questions that agencies should ask before they can effectively incorporate forecasts into their decision-making process.
Agencies with the most sophisticated understanding of the forecasts had the closest connection with forecasters. Therefore, we recommend that you get to know your local or regional NWS forecasters and understand, in advance, the forecast products. We fully agree with the sentiments expressed in the Natural Hazards Observer (Vol. XXIII, Number 3, p. 1) that the forecast process should be open to user involvement. The CPC, local and regional climate offices (e.g., Regional Climate Centers, NWS Weather Forecast Offices), and regional assessment projects (e.g., CLIMAS) are all interested in suggestions from forecast users that lead to better products.
Even if a forecast is sufficiently accurate and relevant, barriers can exist to its appropriate use. For example, some agencies contend they are always prepared for floods. Does being more prepared during El Niño mean agencies can be less prepared otherwise? The issue is not being more or less prepared, but rather how your agency prepares and where your resources are focused. Major institutional barriers to readiness include:
Water management agencies are paving the way for others to take advantage of climate forecasts. However, broad progress requires shifts in agency perspectives and procedures, including recognition that forecasts for winter precipitation in certain regions of the U.S. are useful, especially during strong ENSO events. Now is the time for agencies to develop close relationships with climate forecasters, as well as adaptive management strategies and contingency plans to maximize the utility of climate forecasts for hazard mitigation.
Thomas Pagano, Holly Hartmann, and Soroosh Sorooshian, Department of Hydrology and Water Resources, University of Arizona
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