Catastrophic Coastal Storms offers a solution to the policy problem by proposing a merger of hazard mitigation with development management, basing this on extensive surveys of at-risk coastal locations and case studies of post-hurricane recovery. Starting with the local level of government and proceeding to state and federal levels, the authors propose a strategy for overcoming the formidable obstacles to safeguarding the shoreline population and its structures from hurricanes and other severe storms.
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Catastrophic Coastal Storms
Hazard Mitigation and Development Management
By David R. Godschalk, David J. Brower, Timothy Beatley
Duke University PressCopyright © 1989 Duke University Press
All rights reserved.
Coastal Storm Risks as a Policy Problem
At the heart of American urban growth trends is a disturbing paradox. The areas most attractive to new development are often those most dangerous to life and property. People are drawn to the natural beauty of living on beachfronts, river shores, and mountainsides, despite threats of hurricanes, floods, and landslides. Yet public policy does little to discourage development in hazardous areas, and sometimes it even unwittingly encourages it. Government officials charged with protecting people and property from such natural hazards face political limits on their ability to affect the operations of private development markets, which tend to discount future hazard risks.
This book describes the implications of this paradox for coastal areas. Coastal storm hazards pose a major and growing threat to Public health, safety, and welfare. This threat is an unsolved public policy issue. After an examination of past and present approaches to mitigating coastal storm hazards, we recommend a practical solution to this critical problem through the integration of hazard mitigation measures with the workaday tools used by governments to manage urban development.
Our thesis is that Land use planning and development management offer government officials a practical and feasible way to mitigate the destructive effects of hurricanes and other severe coastal storms. We agree with those who advocate these approaches as among the most promising weapons in the mitigation arsenal (White et al. 1976; Simpson and Riehl 1981). On the basis of our national study of hurricane hazard reduction through development management, we disagree with the pessimists who say that such approaches, while potentially effective, are not politically feasible (Rossi, Wright, and Weber-Burdin 1982). On the contrary, although we recognize powerful obstacles blocking effective hurricane and coastal storm mitigation, we believe that the potential for coordinated intergovernmental programs, in which local development management programs are encouraged and reinforced by strong federal and state mitigation policy, is now greater than ever. The problem is clear, and a solution is at hand; motivated decisionmakers can avert coastal catastrophe if they will take up the challenge.
The Coast as a Risky Commons
Americans view the coast as a national commons where we can find bountiful recreation opportunities and, if we are lucky, sites for retirement or second homes. Images of coastal enjoyment are deeply ingrained in our collective psyche. Coupled with steeply rising coastal real estate values, the combined visions of fun and profit are powerful lures to visitors and investors. Demographic statistics indicate that population growth within five miles of Gulf and Atlantic coastal areas has been three times as fast as that of the nation as a whole (Baker 1979). And during the summer, which is also the annual hurricane season, tourists swell the coastal population manyfold. As of 1984, 66.5 million people (over 28 percent of the nation's population) lived in counties within fifty miles of the hurricane-prone Atlantic and Gulf coast shorelines, at densities much greater than the national average (U.S. Bureau of the Census 1986, 9). Although not all people within these counties face the same storm risks as those on the immediate shorelines, the flooding and tornadoes that accompany a major hurricane can reach far inland.
Few of today's coastal residents understand how a hurricane can damage their beautiful shorefront commons. Some three-quarters of the 1985 population in counties facing the Atlantic and Gulf coasts have moved there since the last direct hit by a major hurricane. According to the National Hurricane Center, this includes almost thirty-two million of the approximately forty-three million residents in these hurricane-prone counties (Hebert et al. 1984; Hebert 1987). Table 1.1 shows the distribution of state population increases since the last direct hit.
Our dominant coastal images involve enjoying sunny skies and sandy beaches rather than fleeing from hurricane winds and storm surges. Yet these negative and often downplayed dangers of coastal life are increasingly significant, precisely because they are underestimated in urban development policy. Coastal development plans, public or private, rarely account for the costs of rebuilding after a hurricane; yet these costs can be staggering to affected individuals, governments, and insurers. By the year 2000 hurricane winds and storm surges are expected to become the leading source of natural hazard per capita property losses, due to the migration of population and investment capital into hazard-prone areas (Petak and Atkisson 1982, 199). Concerned about the accumulation of catastrophic risk and its consequences for insurance losses, the insurance industry has conducted a study examining the effects of two $7-billion-loss hurricanes, seen as a possibility because of the large concentrations of property located along the Atlantic and Gulf coastlines (All-Industry Research Advisory Council 1986). The study concluded that although the existing private insurance system works well in spreading risk among U.S. and international underwriters and reinsurers, two successive $7 billion losses would severely damage the property-casualty insurance industry, resulting in numerous bankruptcies.
Property loss is not the only risk from future coastal storms. Although hurricane-caused fatalities since the tragic 6,000 deaths recorded in the 1900 Galveston hurricane have declined to an average of less than ten per storm in recent years, there is an alarming potential for another killer hurricane due to the increasing population in exposed urban areas. Meteorologists appear to have reached the limits of their hurricane warning capability and thus are no longer able to increase the average warning time of an expected hurricane strike. But while warning times are leveling off, the time required to evacuate people from the path of a hurricane continues to rise by as much as an hour per year in major at-risk metropolitan areas due to continuing urban growth (Griffith 1985). A recent article from the National Hurricane Center (Sheets 1985) stated that evacuation of only the vulnerable residents of exposed communities such as the Tampa Bay area, the Fort Myers area, the Florida Keys, and Miami and Fort Lauderdale, Florida, as well as Galveston, Texas, and Hilton Head, South Carolina, requires evacuation lead times of twenty to thirty hours or more. According to Baker (1979, 263), "The United States may be on the verge of a hurricane disaster involving losses of life not experienced since the turn of the century."
The coastal storm hazard policy problem thus can be defined as continuing urban growth in high-risk coastal areas without a corresponding growth in our ability to protect developed property or to evacuate exposed populations in threatened areas. While some coastal developers may recognize the threat (Miller and Bachman 1984), government action is needed to ensure that a comprehensive policy is put in place. Unless an effective solution is found, the sum of the individual decisions to exploit the coastal commons could add up to a series of unparalleled national disasters. A study of natural hazard management in coastal areas concluded the following:
The disproportionately rapid growth of population in coastal areas makes coastal areas more vulnerable to disaster than many inland areas.
The opportunities to reverse the trends by encouraging coordinated land and water management are more promising than in other parts of the nation.
How these opportunities are grasped will influence whether future events will include a series of national catastrophes ... or conversely, a gradual reduction in national vulnerability to disaster. (White et al. 1976, I-1)
Coastal Hazard Mitigation as a Policy Issue
Both public officials and private developers accept the public interest in keeping the coast open to the people while protecting them from the dangers of coastal storms. The policy challenge lies in striking the appropriate balance between coastal development and hazard mitigation, between economic growth and public safety. Conflict occurs when governments attempt to implement programs that intervene in the market in order to guide development into safe patterns.
Why is this a public policy issue? A hurricane or severe coastal storm in an undeveloped area affects only the natural environment; for a disaster involving injury, death, and property destruction to occur, there must have been human decisions to develop hazard-prone areas in the path of this storm. Otherwise these natural events would have few consequences. Three types of coastal storm impacts argue for government intervention into coastal development processes: threats to public health, safety, and welfare; costs to taxpayers for disaster relief and protection; and losses of irreplaceable natural resources. All of these impacts could be reduced by enacting and implementing effective public coastal storm hazard policy.
Health, Safety, and Welfare Threats
Coastal storm threats to public health, safety, and welfare result from the high winds, storm surges, flooding, and erosion that accompany severe storms. Hurricanes, although not the only type of coastal storm, are the most severe storms, and those with the most commonly measured damages. As shown in table 1.2, between 1970 and 2000 property losses from hurricanes are expected to become the most serious of all natural hazard losses (Petak and Atkisson 1982). Hurricane losses in the year 2000 are expected to top all other natural hazards in terms of per capita ($22.92) and annual ($5.9 billion) dollar losses, as well as housing units lost (96,000). Hurricanes thus replace riverine flooding as the top source of per capita and annual losses and maintain their position as the top source of housing units lost. Only in terms of expected deaths are hurricanes not the most serious natural hazard, ranking third behind tornadoes and earthquakes in death loss estimates for the year 2000. Even so, hurricane deaths are expected to rise over 150 percent by the end of the century, indicating the substantial risks to life faced by coastal residents and emergency crews.
These estimated year 2000 losses are not inevitable. Changes in public policy can substantially reduce the expected future losses. By requiring increased wind resistance and floodproofing and by prohibiting new construction in high-risk areas, hurricane losses can be cut drastically. (Petak and Atkisson 1982, ch. 6) However, even the expected high property losses have not been sufficient to motivate individuals or developers to avoid or mitigate on their own the hazards of high-impact but low-probability events such as hurricanes. Thus the responsibility falls on governments to act in order to protect the public health, safety, and welfare.
Coastal storms cost the federal and state treasuries millions of dollars annually, spreading the costs of protecting coastal development among all U.S. taxpayers. One indicator of the public costs is the amount of federal flood insurance loss claims: over $1.8 billion paid in hurricane-prone states between 1978 and 1986 (see table 1.3). While not all of these losses were due to hurricanes or coastal storms, many of them were. About 73 percent of the national flood insurance coverage is in coastal communities, and coastal claims made up 54 percent of claims payments from 1968 to 1984 (Platt 1985). Another indicator of public costs is the amount paid in disaster assistance. Coastal flooding accounted for 49 percent ($265 million of $539 million) of 1981–1984 federal disaster aid obligations (Platt 1985). And this does not include losses to the local tax base and hence losses in state and local tax revenues resulting from flood damage.
These costs can be reduced by policy changes designed to remove development incentives from hazardous areas. For example, the Coastal Barrier Resources Act of 1982 withdraws federal flood insurance and financial assistance to infrastructure such as roads and bridges within designated "undeveloped" areas of Atlantic and Gulf coastal barriers. This act could save the federal treasury $5.4 billion over twenty years (Godschalk 1984). State and local governments also can realize significant cost savings if intensive development is prevented in high-hazard areas.
Loss of Natural Resources
Coastal areas are rich in natural resources, which are lost through counterproductive efforts to protect development in hazard areas from coastal storms. Beaches, dunes, and wetlands are destroyed both by construction of poorly planned and located public and private projects and by construction of protective works such as seawalls to armor these projects from coastal erosion and storm surges (Pilkey et al. 1983). Construction in these areas interferes with the geological and ecological processes that maintain the natural protective and productive coastal systems. Estuarine wetlands have been damaged by dredge-and-fill activities and by contamination from runoff and wastes. Seawalls and groins have provided localized storm protection but have caused loss of beaches and dunes due to increased erosion from wave action and interference with normal patterns of sand transportation by ocean currents (Platt 1985).
Coastal area management programs can prevent the loss of natural resources through development regulations. By combining preventive measures such as shorefront building setbacks with restrictions on coastal armoring, governments can protect the natural resource systems necessary to maintain the beaches, as well as to safeguard future coastal development. For example, North Carolina has enacted setback regulations that require all major structures in locations subject to ocean erosion to be setback sixty times the annual erosion rate and has prohibited the further construction of seawalls and other permanent protective structures.
Development is not the only cause of natural resource damage, however. Ongoing coastal erosion, hastened by storms, is continually pushing back the coastline. Recent scientific studies have shown a major acceleration of sea level rise, probably caused by the gradual warming of the earth's atmosphere due to the "greenhouse effect" (Titus 1986). The buildup of gases in the atmosphere traps radiant energy that would normally pass outward into space, heating the atmosphere and speeding up glacial and ice sheet melting, which in turn raises ocean levels. While the average sea level rise over the last century has been less than a foot (10 to 15 centimeters), an increase of that much or more (10 to 20 centimeters) is projected by 2025 and of between 1.5 and 6.5 feet (50 to 200 centimeters) is projected by the year 2100. Using the average of one meter of shoreline erosion for each centimeter of sea level rise, the resulting average erosion by 2025 would be 10 to 20 meters (32.8 to 65.6 feet)! According to Titus (1986, 241), "A substantial rise in sea level would permanently inundate wetlands and lowlands, accelerate coastal erosion, exacerbate coastal flooding, and increase the salinity of estuaries and aquifers." He notes that erosion caused by sea level rise could wipe out recreational beaches and greatly increase the costs of flood protection and flood insurance. While Titus concludes that the adverse impacts of sea level rise could be ameliorated through anticipatory land use planning and structural design changes, sea level rise remains to be incorporated into local land use plans in most areas (National Research Council 1987).
Coastal Storm Threats
Coastal storms fall into two types: hurricanes and other severe storms. Both cause coastal erosion and flooding, but hurricanes add two additional threats—destructively high winds and storm surges. Hurricane winds range from 75 mph to as much as 200 mph. Their storm surges are domes of water forty to fifty miles across and from four to twenty feet above sea level which move onto the shore when the hurricane strikes land. Up to 90 percent of hurricane-related deaths and property damage are caused by storm surges.
The major focus of this book is on mitigating hurricane damage because it is potentially the greatest due to the threat of shoreline wind and water surge atop rising floods. However, we recognize that the aggregate effects of a season of "northeasters" or other severe coastal storms can be significant, especially in terms of erosion. Because the mitigation actions taken for hurricanes also reduce damage from other coastal storms, our analysis applies to the full range of coastal storm threats.
Hurricanes are cyclonic storms formed by the release of latent heat from ocean water condensation (Simpson and Riehl 1981). U.S. hurricanes are characterized by counterclockwise, circular hurricane-force winds ranging out some 100 miles around a calm eye averaging 15 miles in diameter and by unusually low barometric pressure which generates sea level rise. Atlantic hurricanes generally occur between June and November, with the largest concentrations between August and October. They are classified according to their wind speed on the Saffir/Simpson Hurricane Scale, which is summarized below (see table 1.4 for the complete scale description).
Excerpted from Catastrophic Coastal Storms by David R. Godschalk, David J. Brower, Timothy Beatley. Copyright © 1989 Duke University Press. Excerpted by permission of Duke University Press.
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Table of ContentsTables and figures vi
1. Coastal Storm Risks as a Policy Problem 1
2. Alternative Approaches to Mitigating Coastal Storm Hazards 23
3. Mitigation after Camille, Frederic, and Alicia 49
4. Federal Mitigation Programs and Policies 94
5. State Mitigation Programs and Policies 126
6. Local Mitigation Tools and Techniques 162
7. Mitigation Practice in High-Hazard Coastal Localities 187
8. Influences on Mitigation Priority, Adoption, and Effectiveness 216
9. Recommended Mitigation Policies and Strategies 233
Appendix: Survey Questionnaire 254