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Home , Beach cusps, Bogue Banks, Coquina, Onslow Bay, Seashell, Southern Islands

RReedduucciinngg VVuullnneerraabbiilliittyy iinn FFiivvee NNoorrtthh CCaarroolliinnaa CCooaassttaall CCoommmmuunniittiieess:: A MODEL APPROACH FOR IDENTIFYING,,,, MAPPING AND MITIGATING COASTAL HAZARDS

Prepared by: Duke University Program for the Study of Developed Shorelines Division of Earth and Sciences Duke Nicholas School of the Environment Prepared for: Division of Emergency Management North Carolina Department of Crime Control and Public Safety

August 2001

TABLE OF CONTENTS

INTRODUCTION: OVERVIEWOVERVIEW AND FINDINGS...... II Lessons Learned and the Ten Rules of Coastal Hazard Mitigation ...... ii Hazards, Economics and Politics ...... iv CHAPTER 1: THE NORTH CAROLINA ...... COAST...... 1 THE GEOLOGIC FRAMEWORK OF THE NORTH CAROLINA COAST ...... 1 Southern Province ...... 1 Northern Province...... 2 NORTH CAROLINA BARRIER ...... 2 HOW BARRIER ISLANDS BEGAN...... 3 The Role of the Shoreface in Barrier Evolution ...... 3 DYNAMICS...... 5 /...... 5 Waves and Wind ...... 6 Vegetation ...... 8 BEACH FEATURES...... 9 Beach Shape ...... 9 Offshore Bars ...... 9 Berms...... 10 Beach Cusps...... 10 Marks, Ripple Marks, and other Bedforms ...... 11 Groundwater on the Beach ...... 11 Beach Erosion ...... 11 ...... 12 NORTH CAROLINA ...... 14 Estuaries of the Southern Province...... 14 Estuaries of the Northern Province...... 15 Estuaries and Development ...... 15 NORTH CAROLINA ...... 16 WHAT'S HAPPENING TO THE BARRIER ISLANDS TODAY?...... 16 Island Migration...... 16 CHAPTER 2: COASTAL HHAZARDSAZARDS AND HAZARDOUS PROCESSES...... 19 WHAT ARE NATURAL HAZARDS?...... 19 HOW NATURAL ARE NATURAL HAZARDS?...... 19 HAZARDOUS EVENTS ...... 19

Hurricanes and Tropical Storms...... 19 Mid-Latitude Storms (Extra-Tropical Cyclones)...... 20 HAZARDOUS PROCESSES ...... 21 CHAPTER 3:3: COASTAL HAZARD GEOINDICATORSGEOINDICATORS ...... 25 GEOINDICATORS...... 25 Natural Clues to Vulnerability...... 25 Topographic Geoindicators ...... 26 Shoreline Geoindicators ...... 27 Geoindicators...... 30 Non-Shoreface Geoindicators ...... 30 CHAPTER 4: ASSESSING COASTAL VULNERABILIVULNERABILITYTYTY...... 31 STEP 1: Acquire Data ...... 31 STEP 2: Data Analysis...... 32 STEP 3: Vulnerability Assessment ...... 32 CHAPTER 5: COASTAL HAZARDHAZARD MITIGATION ...... 35 Accepting Change...... 35 THE BASICS OF HAZARD MITIGATION ...... 36 Mitigation and the Environment...... 36 The Nature of the Planning Area ...... 36 The Hazard Mitigation Plan...... 36 Mitigation Planning Participants...... 37 CHAPTER 6: PSDS COASTALCOASTAL HAZARD MITIGATIOMITIGATIONN ALTERNATIVESALTERNATIVES...... 39 DUNES ...... 39 The Beach- System: Functions, Values and Limitations...... 39 Restoring Dunes ...... 40 Dune Construction/Repair ...... 41 Dune Protection...... 42 Enhancing Interior Dunes ...... 43 ...... 43 ...... 44 Beach Scraping ...... 45 VEGETATION...... 45 Preserving/ and Establishing Native Vegetation ...... 45 INNOVATIVE DEVELOPMENT POLICIES ...... 46 Structural Relocation...... 46 Staggered Shoreline Setbacks ...... 47 Orientation and Placement of Roads and ...... 47 Inlet Hazard Area Restrictions ...... 49 Enforce Building Codes...... 49

Replace Pavement with Porous Surfaces ...... 50 Structural Design Considerations ...... 50 COMMUNITY CASE STUDY 1: ATLANTIC BEACH, NCNC...... 53 COMMUNITY OVERVIEW...... 53 Development...... 53 Population...... 54 Transportation...... 54 Shoreline Changes ...... 54 Geology/Morphology ...... 54 Hazardous Events/Processes...... 55 HAZARD GEOINDICATORS ...... 55 Topographic Geoindicators ...... 55 Shoreline Geoindicators ...... 56 Inlet Geoindicators...... 59 Non-Shoreface Geoindicators ...... 59 MITIGATION RECOMMENDATIONS...... 59 Open Ocean Shoreline...... 60 Area Immediately West of ...... 61 The Circle ...... 61 The Causeway...... 61 "Finger Canals" ...... 61 Post-Storm Redevelopment Issues ...... 61 COMMUNITY CASE STUDY 2: NAGS HEAD, NC ...... 65 COMMUNITY OVERVIEW...... 65 Development...... 65 Zoning Districts ...... 66 Population...... 69 Projected Development and Population Trends...... 69 Transportation...... 69 Shoreline Changes ...... 70 Geology/Morphology ...... 70 Hazardous Events/Processes...... 70 HAZARD GEOINDICATORS ...... 70 Topographic Geoindicators ...... 71 Shoreline Geoindicators ...... 72 Inlet Geoindicators...... 72 Non-Shoreface Geoindicators ...... 73 MITIGATION RECOMMENDATIONS...... 74 Protect the integrity of the ocean beach and dune system and recognize the natural processes and dynamics of the shoreline...... 74 Reduce the risks and vulnerability of structures to damage and loss from hurricanes and coastal storms in advance of such events...... 75 Develop a set of regulations, guidelines, and development review processes that will help preserve topography, vegetation and other natural characteristics...... 75

Investigate more stringent building codes for high hazard areas...... 76 Protect the physical and visual integrity of the estuarine shoreline...... 76 Increase the amount of recreational open space along the ocean and estuarine shorelines and increase open space in other areas...... 76 Consider higher flood regulatory standards for vehicle and equipment storage areas and structures that produce, use or store volatile, flammable, explosive, toxic and or reactive materials...... 76 COMMUNITY CASE SSTUDYTUDY 3: NORTH TOPSAILTOPSAIL BEACH, NC ...... 79 COMMUNITY OVERVIEW...... 79 Development...... 79 Population...... 80 Transportation Issues...... 80 Shoreline Changes ...... 80 Geology/Morphology ...... 81 Hazardous Events and Processes ...... 81 HAZARD GEOINDICATORS ...... 81 Topographic Geoindicators ...... 82 Shoreline Geoindicators ...... 82 Inlet Geoindicators...... 84 Non-Shoreface Geoindicators ...... 85 MITIGATION RECOMMENDATIONS...... 85 Preserve the integrity of the ocean, beach and dune system and recognize the natural processes and dynamics of the shoreline...... 86 Reduce the risks and vulnerability of structures to damage and loss from hurricanes and coastal storms in advance of such events...... 86 Protect the physical and visual integrity of the estuarine shoreline...... 86 COMMUNITY CASE SSTUDYTUDY 4: CAROLINA BEACH,BEACH, NC ...... 87 COMMUNITY OVERVIEW...... 87 Development...... 87 Population...... 88 Transportation Issues...... 88 Shoreline Changes ...... 88 Geology/Morphology ...... 88 Hazardous Events and Processes ...... 89 HAZARD GEOINDICATORS ...... 89 Topographic Geoindicators ...... 89 Shoreline Geoindicators ...... 90 Inlet Geoindicators...... 91 Non-Shoreface Geoindicators ...... 91 MITIGATION STRATEGY ...... 91 Protect the integrity of the ocean beach and dune system and recognize the natural processes and dynamics of the shoreline...... 92 Reduce the risks and vulnerability of structures to damage and loss from hurricanes and coastal storms in advance of such events...... 93 Develop a set of regulations, guidelines, and development review processes that will help preserve topography, vegetation and other natural characteristics...... 93 Investigate more stringent building codes for high hazard areas...... 93 Protect the physical and visual integrity of the shoreline...... 93

Increase the amount of recreational open space along the ocean and estuarine shorelines and increase open space in other areas...... 94 Consider higher flood regulatory standards for vehicle and equipment storage areas and structures that produce, use or store volatile, flammable, explosive, toxic and or reactive materials...... 94 COMMUNITY CASE STUDY 5: OCEAN ISLE BEACH,BEACH, NCNC...... 97 COMMUNITY OVERVIEW...... 97 Development...... 97 Population...... 97 Shoreline Changes ...... 97 Geology/Morphology ...... 98 Hazardous Events/Processes...... 98 HAZARD GEOINDICATORS ...... 98 Topographic Geoindicators ...... 98 Shoreline Geoindicators ...... 99 Inlet Geoindicators...... 100 Non-Shoreface Geoindicators ...... 101 MITIGATION RECOMMENDATIONS...... 101 Protect the integrity of the ocean beach and dune system and recognize the natural processes and dynamics of the shoreline...... 101 Reduce the risks and vulnerability of structures to damage and loss from hurricanes and coastal storms in advance of such events...... 102 Develop a set of regulations, guidelines, and development review processes that will help preserve topography, vegetation and other natural characteristics...... 102 Investigate more stringent building codes for high hazard areas...... 103 Protect the physical and visual integrity of the estuarine shoreline...... 103 Increase the amount of recreational open space along the ocean and estuarine shorelines and increase open space in other areas...... 103 Consider higher flood regulatory standards for vehicle and equipment storage areas and structures that produce, use or store volatile, flammable, explosive, toxic and or reactive materials...... 104 REFERENCESREFERENCES...... 105

INTRODUCTION: OVERVIEW AND FINDINGS

“In recent years the coastal area has been subjected to increasing pressures which are the result of the often-conflicting needs of a society expanding in industrial development, in population, and in the recreational aspirations of its citizens. Unless these pressures are controlled by coordinated management, the very features of the coast which make it economically, esthetically, and ecologically rich will be destroyed. The General Assembly therefore finds that an immediate and pressing need exists to establish a comprehensive plan for the protection, preservation, orderly development, and management of the coastal area of North Carolina.”

- NC Coastal Area Management Act of 1974

The above excerpt from North Carolina’s 50 to 100 years due to the greenhouse Coastal Area Management Act was written 1. Hazards Must be Evaluated Based on effect. As sea level rises, the impacts of in 1974. Unfortunately, it is just as true an Understanding of Coastal Physical storms will move in a landward today as it was over 25 years ago. In light of Processes from a Geologic Point of direction. North Carolina’s burgeoning coastal hazard View. The coastal entire environment management problems, it has become clear including the dunes, beach, and offshore 4. Alterations of Island Environments that new and innovative approaches towards areas are all part of one large Due to Development Should be coastal hazard mitigation are needed. geobiological system impacted by several Repaired and Restored to their different types of processes such as wind, Natural, Predevelopment Setting. This Although traditional approaches to property waves, currents and storm surge. is especially true where the natural damage mitigation must continue to be protective qualities of an island or applied, the purpose of this report is to 2. Recognition of Hazard Areas is community have been reduced. In many promote the recognition, understanding and Imperative. By recognizing hazard areas, cases, this entails little more than application of mitigation approaches based development can be directed away from restoring relatively small areas to their on the physical processes active within the areas most vulnerable to damaging predevelopment state by rebuilding North Carolina coastal environment. coastal processes. dunes or replacing native vegetation.

The goal of the report is to encourage all 3. Approaches to Property Damage 5. Sand Volume and Vegetation Should coastal communities to develop a coastal Mitigation Must be Taken in be Augmented or at Least Maintained. processes approach to property damage Recognition of the Fact That Sea Emplacing new sand from an off-island mitigation using a methodology that Level is Rising. The present interglacial source is better than moving sand from combines traditional and innovative period is resulting in a worldwide place to place on an island. The same is approaches towards coastal hazard shoreline migration as sea level rises over true for native vegetation. recognition, mapping and mitigation. The a sloping land surface. The sea-level rise following points are central to this goal: is likely to continue in the foreseeable future and may accelerate over the next

i 6. Potential for Property Damage must be generalized conclusions, which form the reducing flood damage potential. Recognized as Both Site Specific and basis of the hazard mitigation alternatives Building placement can take advantage Regional in Character. Each area presents and strategies contained in this report, are: of larger dunes to afford wind a unique set of circumstances that protection. Dune width is as important requires unique solutions, although 1. Wide Beaches Protect Property. The more as dune height. general principles can be drawn along beach available to absorb and dissipate the entire coastline. storm-wave energy, the greater the Ideally, no dune on any portion of a possibility for mitigating damage to should ever be removed. 7. The Entire Coastal Zone Must be structures. The greater the distance Removal of interior dunes may lead to Considered When Applying Mitigation between the zone of wave action and property loss and damage that could Plans. Property damage mitigation can fixed construction, the better. When have been prevented if these dunes had no longer be considered appropriate beaches narrow, replenishment or soft remained intact. Killing or removing only for the first one or two rows of stabilization is a means of widening dune vegetation leads to reactivation of houses. Likewise, the coastal zone will them and increasing their “storm buffer” dunes by wind, creating blowouts and continue to move landward as sea level capacity. Beach replenishment is, blowing sand that will be a nuisance, if rises. The storm-to-storm crisis approach however, expensive and temporary. As not a hazard. Sand resources must be should be replaced with a search for erosion threatens, a better alternative conserved, or even possibly added to long-term solutions to this long-term may be relocation. island interiors, and vegetated to problem. stabilize and trap moving sand. 2. Dunes Protect Property. Sand dunes are Lessons Learned and the Ten Rules often referred to as the “barrier” in 3. Vegetation Protects Property. Overwash barrier island, or as “nature’s shock penetration and storm surge damage is of Coastal Hazard Mitigation absorber.” The mass of dune sand may noticeably greater where maritime forest Every hurricane, tropical storm and absorb and dissipate storm-wave energy, is removed for development. This extratropical storm that affects North thus protecting buildings located behind protective effect was well illustrated in Carolina presents an opportunity to observe dunes. Where dunes, rather than South Carolina during Hurricane Hugo and learn more about the interactions buildings, are available to absorb the where neighboring structures suffered between the natural and built environments. impact of waves and storm surge, post- vastly different levels of damage storm beaches are markedly wider. depending on the degree of vegetative Post-storm observations of the impact of Dunes are the sediment reservoir, cover. Similar effects were noted on the Hurricanes Gilbert (1988), Hugo (1989), banked for a stormy day, that provide coast of the Yucatan of Bob (1991), Andrew (1991), Emily (1993), sand to the beach profile as it readjusts Mexico after Hurricane Gilbert in 1988. Bertha (1996), Fran (1996), Dennis (1999) to storm-wave energy. As much forest as possible should always and Floyd (1999) and many winter storms be retained and, where appropriate, on developed shorelines helped define several Dune systems reduce overwash reforestation of areas where trees have principles or lessons learned regarding potential. In addition, interior dunes been removed should be carried out. In property damage mitigation. These provide elevation for building sites, addition to protecting and restoring

ii maritime forests, shrub growth should and scour, as demonstrated during susceptible to property damage than be encouraged in island interiors and Hugo, Gilbert and Floyd. Impermeable development in areas where these issues marsh grass along an island’s backside. roads, drives, parking lots and similar are ignored or overlooked. hard surfaces in constricted spaces 4. -perpendicular Roads Act as between buildings prevent infiltration 10. Property Damage Mitigation is Best Overwash and Storm-Surge Ebb and add to the storm-surge ebb Accomplished at the Community or Island Conduits. Elevating and curving roads so effect. Level. The foregoing principles are they approach the beach at an oblique inadequate if applied singly or in a angle will reduce the extent and amount 7. Setbacks Protect Property. Choosing a piecemeal fashion. Traditional of overwash. Obliquely angled and beachfront building site well back from mitigation techniques that focused on elevated roads also provide a more the ocean is the easiest and least costly the shoreline have not reduced damage torturous return path for storm-surge method of property damage mitigation. to interior island property or, in some ebb flow, thereby reducing scour Setbacks work over the short term cases, shoreline property. Although potential. because the beach storm buffer remains recommended actions may be site- wide and wave energy from major specific, the total set of mitigation 5. Dune Notches Create Overwash Passes. storms is typically reduced by friction on actions must be compatible and applied Notches cut in dunes for beach access, land between the beach and normal over an entire community or island. views or construction sites are naturally shoreline. If a shoreline is retreating, exploited by waves and storm surge and setback requirements are a short- to Some specific lessons that have been learned by storm-surge ebb flows. Such notching intermediate-term solution to property over the years include: can be avoided by constructing damage mitigation. walkovers, elevating structures and • Damage to , sewage, electrical, telephone taking particular care during 8. Elevation Protects. Elevation, whether and cable utilities may be avoided by proper construction. Where present, notches achieved by natural land elevation, installation. should be plugged or equipped with infilling of a construction site or by • Appendages to houses, such as porches or storm barriers that can be used to close building on pilings may be the single decks, whose support columns tend not to be these conduits prior to storms. most important site-specific factor in deeply embedded, are particularly vulnerable to property damage mitigation. Structural storm processes. 6. Overwash and Storm-Surge Ebb is elevations contained in local and state • Intensified when Funneled by Structures. building codes are minimum Although the National Hurricane Center As storm surge overwash an requirements and property owners estimated that Fran’s winds may have reached island and then return to the ocean, should consider them as such. 115 mph, most coastal structures were probably driven either by gravity alone or in subjected to lower wind speeds. combination with onshore/offshore 9. Proper Community Governance Offers a • Breakaway walls on houses were inhibited by, winds, existing structures may constrict Degree of Self-Protection. Development and often caused damage to, the house’s cross- the flow and reduce the cross-sectional where building codes are enforced and bracing. area through which the water must pass. barrier island environments and This leads to increased flow velocities processes are allowed to operate is less

iii • Utilities, such as air conditioners, installed on or Tended to be Developed First, Leaving than an evaluation of the development’s next to breakaway panels inhibited clean High-Risk Sites to Accommodate Growth. hazards and vulnerability. breakaways and caused damage to the utility. This “modern” development, when threatened, often opts for engineering or 6. Politicians are the Employers, While the • Mobile homes, manufactured homes and “hardened” solutions rather than Day-to-Day Work is Carried Out by the recreational vehicles are particularly vulnerable “softer” non-structural approaches to Employees: the Hired Town Manager, to storm processes hazard mitigation Planner and Community Development Personnel. These employees, by and Hazards, Economics and Politics 3. Politicians, and/or the Political Pressures to large, do an excellent job for coastal Which they React, are Oriented Toward communities. They are knowledgeable, Nature is not the only arena of the coastal Giving Priority to Economic Development/ realistic, committed public servants, but zone, and hazardous processes are not the Management, not to Public Safety. they answer to the elected politicians, only performers. Property owners, planners Development is seen as progress and as a not the general public. and public officials can all mitigate the way to increase the tax base. As in the impact of hazards, but their theater is one of pioneer days, such progress is still 7. Collective Community Attitudes are Widely politics and economics. There is a great considered our manifest destiny. Variable. Coastal communities that are diversity of attitudes and responses to suburbs or part of larger urban hazards among North Carolina coastal 4. “Protective” Regulations to Reduce complexes have a high number of communities. Enough similarity among natural hazards are Often Viewed as permanent residents who’s perceived communities exists, however, to allow the Threatening to Developers as well as planning needs differ from communities following generalizations: Some Property Owners. Developers often with more transient populations and resist regulations designed to protect fewer permanent residents, where much 1. Development Sites are Chosen on the property owners or builder occupants. of the property is “recreational.” New Basis of Market Forces, not Nature’s residents in the latter types of Forces. Most coastal communities 5. Politicians are Member of the Economic communities are often inexperienced originally came into existence as port Community. Local decision-makers are when it comes to the dynamic coastal facilities, fishing villages, church camps, often owners of undeveloped acreage, environment and are therefore more hunting clubs and without developers, suppliers of materials, likely to locate development in higher hazard planning. Ironically, these lawyers, businesspeople and risk locations. Further, they also tend to communities are now located in some of professionals who benefit, both lack the political power to influence the most hazardous locations in the personally and financially, from growth planning and other development world. Barrier island communities that and development. Even if no conflict of decisions. were platted in traditional grids over interest is intended, some have a stake in 8. Developers are in Business to make fragile, dynamic environments are the development to protect. The approval of Money, Not to Protect the Public. The most hazardous of them all. a new development, for example, may be emphasis is on build-and-sell, not influenced by the property available analysis of site-specific risk or island- 2. In Older Development, Residents Learned from a board member or by the vision of wide mitigation or future relocation. In from Experience and Low-Risk Sites lumber sales or restaurant patrons, rather addition, the construction industry

iv prospers in the post-storm rush to time of careful relocation and risk upgraded building codes, prohibitions or rebuild. reduction. Houses, hotels and restrictions on future development and condominiums are often rebuilt “bigger mitigation against recurrence of the 9. Catastrophes Often Set the Stage for and better” in the same high-risk hazard. Bigger Catastrophes. Post-catastrophe locations. Big catastrophes, however, “recovery” is a time of shock and haste often bring new and/or stronger to “put things right again” rather than a regulations, higher insurance rates,

v

CHAPTER 1: THE NORTH CAROLINA COAST

The Geologic Framework of the Carolina’s coastal system into northern and Southern Province southern provinces. Each province has a North Carolina Coast unique geologic framework that results in The older geologic units that dominate the distinctive types of barrier islands, inlets and southern coastal province from In general, the geological history of the estuaries with particular wave and tidal Lookout to the South Carolina border North Carolina represents an energies and processes. include formations from the Upper era of several transgressions and regressions Cretaceous (90 million years ago) through of the sea. These have resulted, through the (1.6 million years ago) periods. erosion and deposition, in the formation of In this region only a thin and highly variable several terraces. The most recent terraces, FIGURE 1 known as the Pamlico formation, forms a low, nearly level plain at an elevation less than 25 feet above present sea level.

The materials in this formation are fine sandy loams, clays, and some gravels. Deposits of recent age overlie the Pamlico formation. These include , beach sands and dunes. In marsh areas, the soil consists largely of accumulations of peaty matter. The thickness of the deposits varies from 15 to 25 feet.

The underlying geologic framework of North Carolina’s barrier islands consists of sediment and rock units that range in age from just formed to 90 million years old, and the character of the state’s coastal systems show dramatic differences that reflect the direct influence of the state’s geologic heritage. A line drawn from Raleigh through Kinston and Cape Lookout separates North

1 layer of Quartenary age surficial sand and average slope of 3 feet per mile while the water from the to the sea. Because the muds were deposited during the past 1.6 northern province has an average slope of volume of tidal and river water that must flow million years. The older units are generally only 0.2 feet per mile. This difference in through an inlet is more or less constant over time, composed of harder rocks such as slope causes the ocean surface to intersect when one inlet forms another inlet usually closes. mudstones, sandstones and . each province in two distinctly different Some inlets migrate (e.g., Mason Inlet) while others ways, and caused rising sea levels to form remain in place (e.g., Bogue Inlet). These older rock units are associated with a two kinds of barrier island-inlet systems. The large geologic structure called the Carolina steeper slopes of the southern province have 3. Tidal Deltas. Huge bodies of sand are associated Platform that underlies the region between produced short, stubby barrier islands and with barrier island inlets. Tidal deltas are formed by Myrtle Beach, SC and , NC. narrow back-barrier estuaries. The gentle sand that was fed into the inlet by the longshore During the geologic past, this platform rose slopes of the northern province have currents from the ocean side of each island. The slightly, and the rocks dipped toward the produced long barriers with an extensive seaward body of sand is called the ebb tidal delta. north and east, causing them to be eroded system of drowned-river estuaries. Its size depends partially on the tidal amplitude. and truncated by the shorelines. As erosion The greater the range between high and low , the stronger the currents and the larger the tidal cut deeper along the more uplifted southern North Carolina Barrier Islands coast, the older rock units were exposed. delta. North Carolina ebb tidal deltas extend seaward distances ranging from l00 yards to one Barrier islands are, by definition, elongated mile. The body of sand pushed into the sound by Northern Province bodies of unconsolidated sand that form tidal currents is called the flood tidal delta. offshore islands, separating the open ocean In contrast to the southern province, from the mainland. The following are the younger geologic units - including Pliocene 4. Shoreface (the lower beach). In front of each components of a barrier island: barrier island is a steeply dipping, concave surface and Quaternary sediment formations less than 2 million years old - dominate the that is the innermost part of the . 1. The island. A typical barrier island is a maximum This surface typically extends to 30 or 40 feet water northern province from Cape Lookout to of 30 feet thick and its above water portion is made depth, at which point the sea floor becomes much the Virginia border. In the northern up entirely of sand from the beach (either by wind more gently sloping. This is the shoreface - an province, generally consist of action or storm overwash). A number of sub- integral part of any barrier island that can be unconsolidated muds, muddy sands, sands environments can be identified on each island, considered an integral part of the beach. Fair- and peat sediments that thicken northward such as dunes, marshes, overwash fans, and weather waves push sand landward across the to fill the slightly subsiding Albemarle berms. shoreface, providing the sand that eventually will Embayment with up to 230 feet of sediment. become dunes. During storms, large quantities of Consequently, a gentle depositional 2. Inlets. These are the channels separating adjacent sand move in the opposite direction (seaward) topography is common along the present islands, through which tidal waters from the ocean across this surface. If the storm is big enough, northern coastal system , with older rock are exchanged with river waters from the sand can move well beyond the shoreface and out units buried deep beneath the surface. continents. On natural islands, inlets frequently to the continental shelf. This sand is permanently These two very different geologic open and close (on a decades or millennia time lost from the beach and island. frameworks produce two different land scale). New inlets form during big storms as storm slopes in the North Carolina coastal zone. surge water returns rapidly to sea. In other words, 5. The Beach. The beach, which is actually the upper The southern province is characterized by an inlets are cut through islands by the return flow of shoreface, is like a giant sand pump. Every grain of

2 sand on the “above-water” portions of a barrier and uncomplicated shoreline to become Rivers no longer supplied sand to the island once came across the open ocean beach. highly irregular. shoreline since their mouths were miles Sand comes across either by storm overwash or inland at the heads of estuaries, a situation by the action of wind. In the case of wind blown The intervening ridges between the former which still prevails today. As sea level pushed sand, the sand may go back and forth to the sea river valleys then became relentlessly upward, the newly formed depending on the direction of the wind. When the projecting out into the ocean, which are islands adjusted to their new source of sand beaches are wide and expansive, more sand particularly vulnerable to wave attack. As the and began to migrate in a landward blows into the islands than when the beaches are waves chewed into the , longshore direction. narrow. currents (see the picture below) distributed

the eroded sands either upcoast or The Role of the Shoreface in Barrier How Barrier Islands Began downcoast, forming spits that extended Island Evolution across the mouths of the estuaries. Wind, Barrier islands are a product of a rising sea meanwhile, was piling up large sand dunes, The coast of North Carolina is considered a level. Thus, they have been a particularly forming shore parallel ridges. sand-poor coast, which means that sand prevalent during the ice ages as the supply is low. This is because most of the sea level has repeatedly transgressed and Two events eventually caused the sand ridge- sand that comes down the rivers is trapped regressed across the world’s coastal plains. covered spits to become islands. First, storms The narrow, subtle sand ridges (sometimes eventually breached the spits cutting them labeled scarps or terraces on geologic maps) off from their former longshore sand supply. that abound on the lower coastal plains of Currituck Peninsula provides an excellent North Carolina are former barrier islands illustration of this process. During the last that were stranded when the sea level few centuries 26 different inlets lasting long receded during some past glacial retreat. enough to be named on a map have cut Many coastal communities such as Harkers across this that extends south out of Island, Beaufort, and Morehead City, NC, Virginia. At the same time the gradual sea occupy these former islands, taking level rise (responding to melting ice in the advantage of the safety afforded by their high latitudes) flooded the lowlands behind elevation. the sand dune ridges, eventually isolating them as islands. This is happening today To illustrate the mechanics of barrier island behind the Currituck Peninsula near the formation, we need to consider the major sea Virginia-North Carolina border. level rise that resulted from the most recent Once the sand spits became an island, a retreat of the glaciers. As sea level began to whole new set of evolutionary processes took Figure 2: Estimated TemperatuTemperaturere Change During the rise, perhaps 18,000 years ago, it first over. The main sediment supply no longer Past 40, 000 Years. flooded the former river valleys (See Figure was the adjacent eroding headlands. Instead, 2). This formed the estuaries and sand pushed ashore by waves from the in the upper limits of the estuaries and does simultaneously caused the formerly straight shoreface became the main source of sand. not make it down to the beaches. As a result,

3 North Carolina has thin barrier bearing pre-historic river channels islands that are “perched” on top of underlie the barrier. Topsail Island, older geologic units. where shells of an extinct and associated gravels occur Perched barriers rarely develop a in great abundance, is another profile of equilibrium because they example. These gravels are derived consist of a thin layer of modern from the erosion of Oligocene beach sediment sitting on top of a hardbottom scarps that crop out on shoreface composed of older, the inner continental shelf and are eroding geologic units. Therefore, subsequently transported to the beach North Carolina barriers are actually during storms. thin accumulations of sand perched on remnants of preexisting sediment Headland-Dominated Shorefaces and rock units of variable ages, Headland-dominated shorefaces occur origins and compositions. The on the high inter-river features or complexity of this underlying FIGURE 3 ridges composed of harder sediments geologic framework, together with and rocks of older geologic units. the physical dynamics of an These rocks sometimes may crop out individual barrier island, ultimately segments of the coast. These coastal on the beach, as do the Quarternary determines that island’s three-dimensional rocks found on the beach between shoreface shape, beach sediment segments are often characterized by seaward protrusions (capes) along barrier islands. Kure Beach and Fort Fisher. It is more composition and shoreline erosion rate. common, however, for these rock outcrops The shoreface plays a major role in determining barrier island behavior. The to be on the underwater shoreface. An Today’s large-scale coastal topography is example of a submarine headland is found largely controlled by the riverine drainage North Carolina shoreface is a relatively steep surface extending from the shoreline to the on northern Topsail Island where Oligocene system that was exposed on the continental limestones from high relief hardbottoms shelf more than 10,000 years ago. As sea innermost continental shelf to a depth of 30 to 40 feet. Among other things, the rate of immediately in front of the beach, and level rose, river valleys became inundated extend beneath the barrier island. These and filled with mud and sand. Coastal shoreline retreat, the way an island responds and recovers from a storm, the size of the formations affect the island’s shape and reaches dominated by former river valleys erosion rate, and can have an impact on form the non-headland segments of the dunes and the size of the island itself are all greatly affected by the nature of the incoming waves. coast. These coastal segments are often characterized by rapid rates of shoreline shoreface. recession. The non-headland segments are Nonheadland-Dominated Shorefaces separated by inter-river divides (former Sections of beach between Nags Head and Nonheadland-dominated shorefaces are ridges) composed of older and harder Virginia, for example, contain high common along the North Carolina coast. geologic units that form the headland concentrations of nonshell gravel that is The material that crops out on these usually only found in locations where gravel- shorefaces and affects barrier island behavior

4 is generally composed of four kinds of storms, are telltale indicators of this type of Sand/Sediment sediment: erosive shoreface. Sand comes in all different sizes, shapes and Valley-Fill Shorefaces Seaward-Building Shorefaces compositions. The dominant of Some barrier islands overlie prehistoric river In a few places where there is an adequate North Carolina beach sand is quartz, the valleys that were filled as the sea level rose to sediment supply, the shoreface temporarily same mineral that glass is made from. its present height. Beneath these barriers lie builds, or progrades, seaward with sand that have been ground up by the thick accumulations of soft river and similar to the composition of the barrier waves and other sand grains (which act as an -fill sediments. Barrier islands island. These shoreline segments occur only abrasive) are also important and range from migrate faster across such soft valley-fill immediately adjacent of the capes and inlets sand size (1/16 to 2 millimeters) to their complexes and create indentations in the and are often short-lived phenomena. Two original shell size (a couple inches wide). coastline because these sediments exhibit examples are the eastern tip of Shackelford higher erosion rates that the surrounding Banks and Sunset Beach. of the sand is important because it sediments. Examples can be found in the makes a difference in the rate of shoreline where the former Roanoke A barrier island’s shoreface type is a good erosion. Under the same wave conditions, a River valley passes beneath the barrier in the predictor of future island changes. When an beach covered with fine sand is more likely shoreline reach between Kitty Hawk and kill island does change, in response to a to move around than a beach covered with Devil Hills, and where the former Neuse and hurricane for example, appropriate gravel or boulders. This is simply because it’s Tar River valleys lie beneath Ocracoke mitigation alternatives should be based, in easier to move the small light stuff than the Island. part, upon the island’s specific shoreface big heavy stuff. Grain size also determines type. the slope of the beach. Beaches with finer Inlet-Fill Shorefaces grain sizes tend to be flatter (between the Barrier island segments underlain by the fill Beach Dynamics high and low tide line) with gentler slopes of either historic or prehistoric barrier island than beaches with larger grains. inlets have a shoreface composed of the The beach is one of the earth’s most unconsolidated sand and gravel that back- dynamic environments. Defined as the zone Sand is constantly moving to and from the filled the inlets as they migrated. of active sand movement, and extending beach. This movement (often called the from the toe of the frontal or primary dune littoral drift or longshore transport) occurs Migrating/Retreating Shorefaces to an offshore depth of 30 to 40 feet, the alongshore, or parallel to shore, and on and In areas where narrow and low barrier beach is always changing. offshore, perpendicular to shore. Sand moves islands are actively migrating up and over the due to the joint action of waves and currents. back-barrier estuary, the shoreface is Interest in coastal processes has evolved from Breaking waves kick up sand from the composed of peat and mud sediments. These a purely scientific endeavor into one of great seafloor and the currents move it. If that relatively young sediment units extend from applied societal importance. An quantity of moving sand changes, the beach the estuaries, under the barrier island and understanding of basic coastal processes is will either retreat (erode) or build out crop out within the and shoreface. fundamental to the development of an (accrete). If the quantity increases, the beach Tree stumps and peat blocks, commonly effective coastal hazard mitigation plan. builds out. If the quantity decreases, the seen during the winter months and after beach will retreat towards land. Very often,

5 the cause of change in sand quantity is due Waves and Wind Waves can also transport sand on the land. to humans. For example, when we build During storms, waves wash over the land jetties such as those at Masonboro Inlet on Waves are directly and indirectly responsible carrying sand as overwash. This sand can be Wrightsville Beach, we trap the sand that for almost all sand movement on beaches. deposited way beyond the beach on the was moving alongshore to some other beach. Waves are caused by the friction of the wind center - or even the back part of the island - This starves the beach on the other side of on the surface of the sea. As the wind blows depending on how big the waves are and the jetty and the shoreline there erodes. across the surface, energy is transferred from how long they last. the air to the water. Some general rules of This is part of the reason why sand can come thumb are: 1) Higher winds equal higher Sand from the continental shelf is usually from a wide range of places. If there are waves; 2) The longer the wind blows, the carried onshore during fair-weather and bluffs or cliffs backing the beach, they can bigger the waves; and 3) The greater the offshore during stormy weather. During fair- provide sediment when they are attacked and distance the wind blows (fetch), the bigger weather, sand is slowly moved ashore by the eroded by waves (during storms or fair- the waves. orbitals of waves that are “scraping” the weather). Along the North Carolina coast bottom. During a storm, huge volumes of there are no cliffs. Instead, dunes along our Sometimes waves form currents that carry sand can be moved in just hours because barrier islands supply most of the sand to the sand. The longshore current is the most waves are steeper, and strong seaward beach. important of these. Longshore currents form directed currents are formed. because waves approach the shoreline at an Rivers can also furnish a lot of sediment to angle. The greater the angle between the Water is frequently pushed ashore by the beaches. In North Carolina, however, waves and the shoreline (up to 30 degrees), wind in a storm, temporarily raising the level estuaries often trap sediment miles from the the stronger the longshore current. The of the sea. This is called wind set-up. It is the shoreline and prevent it from reaching island direction of these currents is not set in stone. seaward return of this raised water that beaches. The shells on a beach supply There are reversals in the wave direction carries sand in an offshore direction. So the sediment to the beach as they are broken up approaching any beach, and the longshore energy of the wind and waves causes beach by the waves or by scavenging organisms currents switch accordingly to the new sand to move on, along and off a beach. such as skates or rays. Beaches also gain sand (opposite) direction. While normal fair-weather conditions from the continental shelf. During fair- provide a daily movement of sand, they do weather, waves slowly push ashore sand and Most of North Carolina has longshore so on a much smaller scale than the wind shells from water depths as great as 30 or 40 currents moving from the north to the and wave conditions during a storm. Storms feet. An increasingly important source of south, or “down the coast.” Indicators of can provide instantaneous adjustments in the sand on North Carolina beaches is longshore transport at work in North dynamic equilibrium of a beach. nourishment sand which is dumped by man. Carolina include inlets that migrate (e.g., The natural laws that govern beach dynamics Many communities now nourish their South Topsail) and the build-up of sand on dictate that they build up in good weather beaches, bringing in sand from inland one side of a groin or jetty and erosion of and retreat (usually only temporarily) during quarries, local inlets or from the offshore sand on the other side of the structure (e.g., storms with big waves. Beach behavior is shelf. Masonboro Inlet). dependent upon four factors:

6 1. Wave energy This build-up of island elevation is a critical National Seashore: Shackleford Bank and 2. Quality and quantity of beach sand part of island evolution during a rising sea Core Banks. 3. Shape and location of the beach level. The overwash phenomenon was amply 4. Rate of sea level rise demonstrated on many East Coast barrier The dominant winds in this area are from islands during the 1991 Halloween storm. In north (winter) and the south (summer). In general, beaches maintain a natural the village of Rodanthe, NC, overwash fan Shackleford Bank, a wide, high sand rich balance referred to as a “dynamic thickness from the storm exceeded five feet island is oriented east-west and for equilibrium” of these four factors. When one in places. significant periods of time each year, sand is factor changes, the others adjust accordingly blown into the vegetated dunes. Core Bank, in order to maintain balance. For example, Barrier islands also do not exist where tidal a narrow low-lying island with few dunes is beaches will react to human impacts in ways amplitudes are in excess of 4 meters. Why oriented north-south. On most days of the that restore the dynamic equilibrium, but this is the case is not entirely clear. year sand blows up or down the island, that may damage or destroy buildings and According to studies made by Miles Hayes, rather than across. As a consequence, little infrastructure. control the spacing of inlets, which is sand is blown from the beach to the island another way of saying that tides control the interior and few dunes form. Barrier islands respond in predictable and length of islands. With large tidal sensible ways to all kinds of natural events amplitudes, where a lot of water must flow The sand supply of an island is another such as storms, rising sea levels, retreating in and out of inlets, inlets are closely spaced major factor determining island width and shorelines and the migration of inlets. In a and islands are short. The Georgia islands, volume: the bigger the supply the greater the technical sense, barrier islands exist in a where normal tides are 7 feet, are good width and volume. Occasionally, as in some dynamic equilibrium involving a number of examples of short islands. With small tidal Texas islands and those on the Mississippi factors including waves, tides, wind, sand amplitudes, where less water must flow in Delta, sand supply is directly traceable to supply, underling geology, vegetation and and out of the sounds, the inlets are widely river sources. Mostly however, American sea level change spaced and the islands are long. The NC barrier islands receive their primary sand Outer Banks has long islands and a tidal supply from the adjacent continental shelf. Waves range of less than three feet. Why this sand supply varies both aerially Waves are critical in barrier island evolution and temporally along barrier island chains is because they are responsible for carrying Wind not well understood. In some cases, sand sand to the beach from either the continental Over time, wind is capable of carrying large supply probably will be controlled by the shelf or from adjacent islands. This process is volumes of sand from the beach into the nature of the materials that the island is so important that barrier islands do not exist dunes. Prevailing directions of wind are migrating over. on shorelines of very low wave energy (e.g., important in determining the overall island the shoreline bordering the northeast sand volume that is available to wind move The geologic framework or underlying corner of the of Mexico). Storm waves off the beach and into the island. The geology of barrier islands controls the wash over the island and bring huge volumes importance of wind is demonstrated by the location of some islands and also affects the of sand into the interior of the island. difference in width and sand volume of two size and composition of the sand supply. On adjacent islands in the Cape Lookout the Outer Banks of North Carolina,

7 stretches of gravel beaches almost always through the dunes is important because it and Live Oak are the principal floral correspond to the offshore location of old brings sand to the island, raising its components of the forest. The diversity of deposits of river gravel laid down when the elevation. This is an important way for the vegetation on North Carolina barrier islands sea level was much lower. Fossil shells and island to compete with a rising sea level. depends on their size and elevation, which in fossil shark teeth are common constituents of turn controls the extent of exposure for some barrier island sand (e.g., Topsail Sea Oats are easily distinguished by their plants to wind and salt. Island), all derived from underlying strata. long, thin, protruding stalks with grains of Even the erosion or migration rates of attached “oats.” These “oats” are flat, On , which is wide and has islands are partly controlled by the yellowish oat-like spikelets which grow in high dune ridges, there are over 500 underlying geology. Islands underlain by the summer and fall (from June to different species of plants. On Core Banks, mud are prone to more rapid retreat than are November). The stems are cylindrical and which is low, narrow, and frequently washed islands underlain by sand. the linear-shaped leaves grow on both the over by storms, the number of naturally- base of the plant as well as along the stem. occurring plant species drops to 25. In Vegetation between these two is , From northward, dune grass which has almost 300 species. Shackleford Vegetation plays a major role in barrier is composed predominantly of American has high dunes, but it is not as wide as island evolution as well. For example, beach grass (Ammophila breviligulata). This, Bogue Banks. These three adjacent islands onshore winds blow a lot of sand into the too, grows well after being buried by sand. illustrate how forest species diversity adapts islands. However, when the winds reverse But in contrast to the Sea Oats, American to the specific nature of the barrier island. and blow offshore, not nearly as much sand beach grass grows well laterally, and between is carried towards the sea. This is because storms it will even spread out to the edge of dune vegetation holds the sand in place once the normal high water line. American beach The third major vegetative component of it gets onto the island. grass is increasingly planted in the dunes by barrier islands is the salt marshes found

oceanfront property owners well south of along the sound shoreline. This shoreline is Dune Vegetation Cape Hatteras because it grows rapidly and much quieter than the ocean beach, with the The manner in which dune vegetation transplants easily. American beach grass is only significant wave action generated by spreads seeds and rhizomes is a major control best distinguished as the near beach dune offshore winds or storms. The dominant of island topography. Sea Oats, the grass without stalks. It also remains partially marsh grass in North Carolina is Spartina dominant southern US dune plant, tends to green during the winter. which is adapted to the repetitive wet and form in clusters and as a result natural dune dry cycle of the tides. The thick lines on southern islands have gaps. The gaps Maritime Forests congregation of marsh grasses baffles what are used by storm overwash to bring sand The forests found on the back side of barrier wave energy does strike the sound shoreline, onto the island and build up its elevation. In islands are called maritime forests. They have which then traps the sediment from the contrast, dunes dominated by American a smaller number of plant species than water much like dune grasses trap it from the beach grass will have fewer gaps. This mainland forests due to consistent high air. The marshes then build up mud and prevents storm overwash except in the larger winds and the salt spray from the beach. On peat as the grasses grow, trap sediments, die storms. Penetration of the storm waves most North Carolina barrier islands, cedars and are buried.

8 Sand supplied by overwash fans also builds the characteristics of the wind and waves. its shape is. Farther north at Topsail Island up the elevation of the marshes, allowing Grain size can also control the slope of the and in places along the Outer Banks, peat them to survive during a rising sea level. The beach. outcrops are visible on the beach. This shows function of sea level change is discussed how fast the island is migrating because below due to its special role in island The most spectacular changes in beach those peat deposits are the buried remnants migration. As already mentioned, barrier shape, changes that can happen very quickly, of freshwater marshes that used to be on the islands are a product of a rising sea level. No occur in storms. When storms occur, sand is backside of the island! sea level rise means no valleys are flooded to often moved from the upper beach to the form estuaries, and no islands are built across lower beach or offshore. This flattens the Our beaches exist in a state of dynamic the mouths of estuaries. beach. Have you ever visited a beach after a equilibrium with the various forces acting on storm and noticed that the beach is wide? them each minute of every hour of every Beach Features Beaches flatten in a storm to spread the day. Man, in an effort to preserve the natural energy out over a broader zone and take on a beauty of the beach, has often become Who do the beaches belong to? Are all the dissipative beach profile (also called a another force acting on the beach. The beaches owned by private owners? No. Can “winter” beach shape). This is a defense beaches respond to man’s impacts as well. you access the beach from someone's mechanism by the beach to prevent losing What if someone builds a wall or structure property? Probably not. Some, such as Cape even more sand. Between storms and in that disrupts the dynamic equilibrium? Hatteras National Seashore, are state or quiet weather, this sand moves ashore and Mother Nature will react just like to any federally-owned. In North Carolina, the the beaches tend to steepen and get other change, but oftentimes the reaction is beach itself is public property, but gaining narrower. Have you been to the beach in the not what man wanted or intended. The access to it is often restricted by private summer and noticed that the beach is features you see on the beach, both natural property. If you are lucky enough to enjoy a steeper? This is commonly referred to as a and artificial, are direct representations of stroll on one of our magnificent North reflective beach profile. the dynamic forces at any given beach. Each Carolina beaches, keep an eye out for the feature, whether it be a sandbar, berm, dune, following features, each a clue to the story of Sometimes the underlying geology controls beach cusp or ripple mark, tells a story about the beach. beach shape or profile. If the barrier island what is going on at that beach. If we know has rocks, peat or mud underneath it how to listen, we can read the beach for its (instead of being a huge pile of loose sand), clues. Beach Shape these harder sediments may stick out on the The shape of a beach is oftentimes called a beach profile. Offshore Bars beach profile. The profile extends from the dune, across the beach, and offshore under Have you ever noticed some rock-like Sandbars are underwater mounds of sand the waves. The beach shape or profile is materials at Kure Beach? These are rocks that form close to the beach anywhere from controlled by all three of the factors in the made out of old shells that were deposited 100 to 300 meters offshore. Some beaches dynamic equilibrium of the beach. The and buried thousands of years ago. They have more than one sandbar, with the bar beach automatically responds to any change now crop out on the beach and dunes in this closer to the beach called the inner bar and in sea level, the amount of sand available and area and control where the beach is and what the farther one called the outer bar.

9 From the beach you can tell where these part of it can become exposed at low tide. These scarps look like miniature cliffs on the underwater features are by where the waves Have you ever been at the beach at low tide beach, except they are right at the water’s are breaking. Sandbars are a sudden and been able to walk along the water’s edge edge instead of at the back of the beach! shallowing of the seafloor that trip up waves only to have a large puddle of water in a before they would without a bar. If the bar is depression next to you? Some people call the Beach Cusps far enough offshore, the waves that break on high part you’re walking on a ridge, with the the bar might reform and break a second low depression called a runnel. Oftentimes, Beach cusps can sometimes be carved out of time on the beach. Sandbars come in many these features will have ripple marks on the the berm of a beach. These horn-like features different shapes and sizes. Some are crescent surface of the sand left behind by the moving consist of protruding sections of the beach shaped while others are long and straight. water. Sandbars are an integral part of the that alternate with small embayments. dynamic beach, and if you know how to read Beach cusps give the beach a wavy or Wide and low bars may contain a huge the waves you might just spot one. undulating appearance. If you have ever volume of sand, while smaller and narrower walked along the water’s edge only to find ones may not contain as much sediment. Berms yourself going up and down a gently rolling Bars can extend for miles down a beach, surface, you’ve probably been walking across with gaps in between the individual mounds The berm is the flat part of the beach that a series of beach cusps. These cusps are of sand. Over time these bars move around you sunbathe on. There is a berm crest typically uniformly spaced (anywhere from in response to waves and currents much like somewhere close to the water that is the centimeters to tens of meters apart) and look the beaches do. Storms can create sandbars highest part of the berm. The rest of the like arcuate from above. where previously there were none, with all berm usually slopes slightly landward back to the sand they move offshore being dumped the toe of the dunes. Some beaches might When you are on a beach with beach cusps, in one place. After the storm has passed, fair- have more than one berm, kind of like you will notice that the waves seem to wash weather waves will slowly move that sand terraces. Berms probably form during storms up in the embayments only. The wave swash from the bar back to the beach. If there are that are long gone, and if there is more than is deflected by the horns into these rounded- two sandbars offshore of a beach, and both one, then they each represent different out areas. In this way the horns are usually are moving about with the changing waves, storms. The back part of the berm is thought gaining sand (accreting) and the the two bars can merge into one. Scientists at to be the farthest back that storm waves cut embayments are losing it (eroding). The Duck, North Carolina, are using time lapse into a beach. So, each berm indicates a difference in elevation between the horns video cameras to watch the sandbars found current or former equilibrium position of the and embayments is usually on the order of a there. They use the position and shape of the beach. On nourished beaches like couple feet or more. Scientists are not breaking waves to tell them where the bars Wrightsville or Carolina Beaches, berms are exactly sure how beach cusps form, but they (usually two) are, what shape they are, and artificially created when new sand is dumped do know that they are ephemeral features how they are moving over time. on the beach. A lot of times, however, that can change shape and size with any engineered berms are not in dynamic given wave conditions. Sometimes the bars march right up to the equilibrium with the waves and currents. beach and become a part of it. When a sandbar is welding itself to the beach, the top Scarps can be cut in an artificial berm as waves attempt to create a more natural berm.

10 Swash Marks, Ripple Marks, and beach when the groundwater table is Beach Erosion intersected by the surface of the beach. They other Bedforms commonly form after storms when the beach Nipping away at the edges of the continent, The surface of the beach exhibits a diverse surface has been moved back by erosion. ocean waves are slowly taking away land variety of patterns. These so-called bedforms area. At the same time, the continents are and structures form as a result of the currents Groundwater on the Beach enlarging by such processes as mountain in the wave swash, moving the sand around building and the growth of river deltas. until the grains settle down. Each type of Have you ever sat and watched the swash Today the forces of the sea are winning and bedform provides a clue to the currents and running up a beach, and noticed that the continents are shrinking since sea level is waves that created them. One can actually sometimes the swash disappears into the rising faster than the continents can provide observe these features forming by standing in sand instead of running back to meet the new land. the uppermost swash zone of the beach. next wave coming in? This indicates that the water table is low on the beach, the sand in A shrinking continent translates into trouble One of the more prevalent bedforms is swash the swash zone is dry and sucks up the water for people when buildings, highways and marks. These are small ridges of sand or brought in by the swash. When the swash services are built next to the shoreline as they debris that are left behind by the most does not sink into the sand like a sponge, so often are in North Carolina. In the landward reach of an individual wave swash. but instead washes back to the sea, the water absence of buildings, land is lost when the At low tide, the entire beach may be covered table is high on the beach. This means that shoreline moves back but the beach remains by these long wavy lines, each a reminder of the line where the water table intersects the as a wide, healthy buffer of sand. No erosion the single wave that created it. surface of the beach is farther up the beach problem and no beach problem exist as long Ripple marks are another bedform found in than where the swash is running back and as no buildings are built next to the the of the beach. These forth. shoreline. bedforms can form anywhere there are the right kinds of currents and sediments. These So why is the position of the water table on Shoreline erosion has been with us for a long ridges of sand, larger than swash marks, line the beach important? The water table is time. The Romans complained about it and up in a repetitive pattern perpendicular to important because it influences how much built structures to hold the shoreline in the direction of the water current or wind sand will be picked up by the swash and place, usually near harbor mouths. The that created them. They look like miniature waves. If the water table is low, all of the erosion problem is immensely greater now dunes and can cover very large areas. Ripple sediment that is being carried by the swash is than it was in Roman times because the marks are formed in the sand by wind or deposited on the beach as the water shorelines of the world are now jammed water moving over the beach surface at a infiltrates the sand. If the water table is high, with buildings, in open defiance of the forces high enough velocity for the sand to be more sediment can be picked up by the of nature. picked up and moved. swash and waves since each sand grain is already surrounded by water. The causes of shoreline erosion have been Another type of bedform is rill marks. Rill the topic of intense study for the last several marks look like small streams crossing the decades. Although it's still difficult to sort beach. They form as water pours out of the out all the factors involved, we are getting closer to understanding the natural balance

11 between processes and materials at the shore, coast, but is not important along much of patterns of the region, winds will blow as well as man’s influence on that balance. In the East Coast and North Carolina where onshore at least some of the time. These North Carolina we understand the problem rivers dump their sand load in the upper winds occur most commonly when the land probably as well as in any other state. Rising estuaries, miles from the ocean shoreline. is warmer than the sea, causing air to rise sea level is the dominant force behind long- from the land, which in turn causes air from term shoreline erosion. In the short-term, People have caused further interruption of the sea to blow onshore to replace it. The storms can cause tremendous amounts of the shore’s sand supply by dredging channels winds can often reach great speeds that move local erosion. for boat access to inland waters and ports. large amounts of sand in short periods of Many, if not most, inlets in North Carolina time. You may even run across a glass bottle Sea Level rise will likely accelerate in coming are periodically deepened by dredging. left on the beach that is “frosted.” The sand decades due to the Greenhouse Effect. This When the deepened channel is protected by grains were moving fast enough so that shine expected climate change may also increase jetties, long walls built parallel to the and clarity of the glass bottle are essentially the size and frequency of storms, although shoreline, the cutoff of sand supply is almost sandblasted off. this is less certain. The 1997-1998 El Nino total and erosion rates skyrocket. Jetty- temporarily raised sea level by 1 to 3 feet off caused erosion can extend down the coast for Evidence of the beginnings of dune South America, and increased storminess many miles. development could be right in front of your and along our Pacific . eyes if you’re on a beach. Dunes commonly La Nina, the opposite of El Nino, seems to Dunes begin as piles of sand accumulated in the lee increase storminess on the East Coast. of beach debris such as piles of seaweed, A dune is a pile of wind-blown sand. They clumps of salt marsh “straw” and a whole The volume of the natural sand supply is come in a huge variety of sizes and shapes, host of human garbage (fishing nets, bottles, another major erosion factor. In North depending on the amount of sand available, etc.). Beach debris slows down wind Carolina sand arrives on the beaches mostly the size of the sand, and the prevailing wind velocities or blocks the wind, causing sand to from the continental shelf, pushed ashore by directions. Over time they can grow, shrink, accumulate. Eventually, seeds of dune grasses the action of fair-weather waves. Big storms or move (migrate) in the direction of (especially Sea Oats) find their way to the tend to take the sand away and can carry it prevailing winds. They can be created and new piles of sand, germinate, sprout and offshore, sometimes too far off to be destroyed by either nature or man. Dunes start to trap sand. As the plant grows it recovered. After Hurricane Fran, there was can roll over trees and buildings or be continues to cause more sand to gather. If all very little beach recovery on Topsail Island, washed away by the next storm. goes well and the surf zone is far enough leaving many buildings in immediate danger away a new dune is born! As the dune grows from the next storm. The beach is the sole source of sand for the vegetation keeps moving up and out, coastal dunes, and every single grain in a holding much of the sand in place. On most American shores, humans are likely sand dune has come across the beach at one the principal cause of erosion. For example, point in time. The sand can come ashore Dune Sand and Stratification from both the sound beach and the ocean construction of dams has trapped the supply The sand that makes up the coastal dunes of side beach. Dune building is helped along by of river sand to the beaches. This problem is North Carolina is usually finer than the sand the onshore winds characteristic of . typical for and parts of the Texas grains on the beach. Wind cannot move the Regardless of the general wind circulation

12 large particles that waves do. Consecutive sediment. When the grass is removed by grapes are found in patches on the top of layers of dune sand and other sand-sized storms, or even by overgrazing, the dunes are Run Hill Dune. These grapes came from sediment build on top of each other and, destabilized and can begin to migrate vines that were growing on the tops of the over time, the layers form a unique type of landward. trees now buried by the dune. stratification called wind cross-bedding. Cross-beds, which can usually be seen in Artificially-induced dunes are often dunes The dunes of coastal North Carolina form a erosion scarps next to the beach, have several built up by the planting of grasses or somewhat continuous ridge of sand facing sets of sand layers that incline at different through the use of sand trapping fences. the sea. The size of the dunes is mainly a angles. Each set of layers indicates the former These are common along the shores of function of sand supply -- the larger the surface of the dune. In North Carolina, the North Carolina as many property owners supply from the beach, the higher the dunes. dune stratification is usually seen as fine, attempt to build up dunes in front of their Most dunes have gaps between them where sand-sized shell material or heavy homes. Another form of artificially induced the storm waves penetrate into the islands. interspersed with regular quartz sand. The dunes is the bulldozed dune. This practice When the foredune is very large, like the 30 layers of shells are usually brown in color becomes more widespread each year in foot high dunes on Bogue Banks, there are and the layers of heavy minerals are black. North Carolina. These dunes are described no overwash gaps. Overwash deposits are in more detail later. easily distinguishable from dune sands You have to stand very close to an exposed because of their high shell content. dune surface to see the individual layers. The Medanos are the third type of dunes and layers are very thin, often one to two grains derive their name from the Spanish word for Why do some barrier islands and beaches of in thickness. They probably form in a burst “coastal sand hill.” Medanos are a distinctive North Carolina have many dunes and some of wind, which brings in a new layer of type of unvegetated dune. They are high, have only a few low ones? The answer is quartz sand. Between bursts, lower velocity steep, isolated sand hills ranging in height largely related to wind direction. Core Bank, winds cause the lighter materials to be blown anywhere from tens to several hundreds of oriented north-south, probably does not away, leaving behind heavier grains and thus feet. Medanos are formed by winds moving have dunes because most winds blow up and forming a layer. sand upward toward the summit from down the island (parallel to), not across it. In several directions. Despite their lack of contrast, adjacent Shackleford Banks, with Dune Types vegetation, Medanos have very little overall an east-west orientation, has very large dunes There are three types of dunes in North migration because of the number of different because most of the winds blow across it. Carolina:1) vegetated, 2) artificially induced, wind directions that transport wind to the and 3) medanos. Vegetated dunes can be dunes. These dunes may simply represent Blowouts seen on most of North Carolina’s barriers places where there was an exceptionally high A blowout is a flat area or surface in a dune and beaches. One exception is Masonboro amount of sand available on the beach. field that lies below the elevation of the Island, which is overwashed so frequently Medanos can be found on the Outer Banks adjacent dunes. These are formed by the that dunes have no time to form. When in Nags Head and Kill Devil Hills and wind removing sand (i.e., wind erosion). present, the vegetation is usually American include Jockey’s Ridge, Run Hill Dune, and Blowouts are flat because the sand is blown Beach grass or Sea Oats. The vegetation the Wright Brothers Memorial. The latter is away until the sand surface reaches the top of serves as an anchor for wind-blown now held in place by a mowed lawn! Wild the water table. The wet sand resists being

13 blown away and the surface becomes days on the upper beach, wind will blow Bulldozing dunes is not a good thing for vegetated. You can this by digging a hole away the finer sand on the surface, causing a beaches. For one, it is a form of beach with your hands on a North Carolina layer of shells called a “shell lag” to form on erosion. For another, it kills all the blowout. Less than a forearm length below the surface. organisms in the beach -- the mole , the the surface, you will reach freshwater. The coquina , and all the microscopic best place in North Carolina to see blowouts Natural dunes, especially those with roots organisms that live between sand grains. For is on the western half of Shackleford Banks. entangled throughout the sand, provide a days after bulldozing, seagulls have an solid (if temporary) bulwark against a minor unexpected bonanza, swooping and grabbing Bulldozed Dunes storm. When attacked by waves, they the stranded and struggling critters of the In North Carolina, it is legal to bulldoze quickly form a scarp or small . beach that are now high and dry in the beaches to form dunes or piles of sand up Subsequent waves are at least partly reflected bulldozed dune. For a few days after against buildings for storm protection. from the scarp, rolling back down the beach bulldozing, the odor of rotting organisms Almost every beach with buildings on it is and smashing into the next wave coming can provide an unpleasant atmosphere for bulldozed occasionally, usually after storms. ashore. Bit by bit, however, the dune scarp beach strollers. moves landward under wave attack. It is easy to spot bulldozed dunes because North Carolina Estuaries they contain a lot of shell material - a rare Helping to reinforce and strengthen natural component of natural dune sand. After a few dunes (in addition to the beneficial effect of North Carolina’s estuaries are drowned plant roots) are electronic forces between the lowlands that lie behind the barrier islands. uniform sized sand grains In places where these lowlands are drowned FIGURE 5: Beach ScraScrapinping in Ocean Isle Beach, NC and the water between the river valleys, the ocean has flooded up the prior to Hurricane Floyd grains. These are called river’s channels to the point where the valley Vanderwaal forces. In bottom rises above sea level. The resulting bulldozed dunes, which are shore-perpendicular estuaries have two made up of beach sand sources of water: rivers and inlets. with a wide size range of quartz grains and shell Estuaries of the Southern Province fragments, neither roots nor Vanderwaal forces The narrow, coast-parallel estuaries that back work. As a consequence, the barrier islands of the southern province the dunes erode with much range from open water to areas dominated greater ease. The bulldozed by salt marshes and tidal creeks, depending sand, minus the animals on the width of the estuarine system. that once lived in them, Estuarine systems tend to become narrower, returns the beach (usually and open-water bodies become smaller, during the next storm). toward the southern end of the province.

14 Because of their relatively small surface area, weather events. Normal wind tides are minor Estuaries and Development water in southern province estuaries (less than 1 foot) with storm tide amplitudes experience minimal effects from waves and ranging from 3 feet up to 10 feet during Most estuarine shorelines in North Carolina wind-driven tides. Consequently, the hurricanes. In general, the back-barrier are actively eroding, although erosion rates perimeters and interiors of these estuaries are sounds of the northern province tend to be range from a few feet per decade in the dominated by sloped and extensive irregularly flooded, wind-tide-dominated innermost and small tributary estuaries up to Spartina salt marshes riddled with tidal coastal systems surrounded by scarped and an average of 3 feet per year in exposed low channels. rapidly eroding marsh and sediment bank sediment banks and marsh peats in the outer shorelines. estuaries. These narrow estuaries are regularly flooded, tidal-current-dominated coastal systems that Sediment Shorelines Actual erosion rates for a specific stretch of estuarine shoreline is highly variable and have been highly modified by human About one third of North Carolina’s depends on many factors, including: activity, including an extensive network of estuarine shoreline is dominated by sediment dredged channels and associated spoil banks consisting of sediment beds of • Fetch – the average distance of open water islands. Quaternary age or older. Sediment bank across which the wind can blow in front of the shorelines consist of a wave-cut platform and shoreline Estuaries of the Northern Province an associated wave-cut scarp that are eroding back into older sediments. The sand that • Water depth, bottom slope and beach – bottom The back-barrier sounds of the northern forms the beach along the shoreline is characteristics of the nearshore area and the province are medium to large, coast-parallel derived from the erosion of the sediment presence and width of a sand beach between estuaries. The presence of only four major bank. the eroding sediment bank and shoreline inlets in more than 190 miles of barrier islands, plus a major input of fresh water • Bank height and composition – height of the These eroding sediment bank shorelines from rivers draining the Piedmont and sediment bank at or immediately behind the border land that is in greatest demand for Coastal Plain, result in estuaries with low- shoreline and the hardness of the sediments or homesites. Low sediment bank shorelines amplitude, regular astronomical tides and rocks that compose the bank (less than 5 feet) are the most common type highly variable salinities. Only in the regions • of sediment bank. Vegetation – type and abundance of vegetation around inlets, subject to direct oceanic occurring on the sediment bank and shoreline, influences, do waters exhibit regular and in the offshore area astronomical tides and develop high-brackish Organic Shorelines • salinities. Approximately two thirds of North Shoreline geometry, orientation and geographic Carolina’s estuarine shoreline is dominated location – general shape of the shoreline, Because the sounds of the northern province by the vegetative growth of swamp forests direction the shoreline faces and geographic have relatively large surface areas with and marsh grasses. Organic shorelines are location within the estuarine system moderately uniform depths and no interior characterized by peat sediment composed of salt marshes, they are highly influenced by organic matter with varying amounts of fine Most estuarine shoreline erosion takes place wind waves and currents as water moves in sand and mud. in direct response to high-energy storm. response to irregular and rapidly changing Therefore, the amount of recession at any

15 location is quite variable from year to year In microtidal areas, such as North Carolina, down, even including those islands that were and depends on the frequency of storms; the sediment normally does not flow very far building seaward just a millennia ago. type and direction of approach of any given seaward. Rather, flat areas of sand are Two causes have been suggested for the storm; the intensity and duration of each deposited on the landward side of the inlets narrowing of barrier islands. One is that storm; and the resulting wind tides, currents forming extensive flood tidal deltas. The man, by damming rivers, jettying inlets, and waves produced by that storm. combination of shifting sediment, tidal seawalling beaches and dredging channels action and waves causes many inlets to and harbors has precipitated a sand crisis. North Carolina Inlets constantly change position. As a result, tidal This shortage of sand is causing worldwide deltas, as well as areas of land located on erosion. Inlets are waterways between islands, or either side of inlets, are highly unstable and spits, that serve as passages through which can change their profiles in response to even Another view is that island thinning is due to sediment is transported. There are 23 inlets minor changes in the inlet. sea level rise. If this is the case, the narrowing along the North Carolina coast. Four of distances between ocean and sound will these inlets are located north of Cape Because of their complex nature and scales of facilitate rapid and frequent cross-island Lookout and the other 19 are to the south. motion and geomorphic change - which overwash and allow efficient and rapid island range from seconds to centuries - little is migration in the future. Thus the islands The northern inlets along the Outer Banks known about fundamental processes such as may be effectively preparing for the are characterized as being wave-dominated short- and long-term migration trends and upcoming acceleration in the rate of sea level with large flood tidal deltas. The tidal range cycles of an inlet, stability of the navigation rise. Very likely, both of the suggested causes for this region is microtidal (0-2 m). channel, shoreline change within and near are behind the worldwide erosive state of Historically there have been many inlets that an inlet, the response of inlet shoaling to barriers. have migrated up and down the Outer varying wave and current conditions and the Banks. All were created by storm processes distribution of sediment transport within the Island Migration and continue to be dominated by storm inlet proper. breaching. Island migration is an amazing geologic What's Happening to the Barrier phenomenon. It wasn’t even recognized until a couple of decades ago. During the The 19 inlets to the south of Cape Lookout Islands Today? are traditionally smaller migrating inlets that l930s and '40s shoreline erosion was very are dominated by tidal and as well as wave evident on the NC Outer Banks and a Something fundamental has occurred within massive dune building effort was begun to processes. Many of the inlets in southeastern the last few hundred years. Virtually all North Carolina are maintained by the US save them. A continuous dune was barrier islands in the world are eroding. On constructed almost from the Virginia border Army Corps of Engineers for navigational islands with open water (as opposed to salt purposes. Others are in a natural state and to well beyond Cape Hatteras. It made marsh or mangroves) behind them, erosion perfect sense to do this in the context of the behave in response to amount of sediment is occurring on the sound side. It is clear available to the inlet system, tidal prism, prevailing ideas about barrier islands. It soon from observations on undeveloped barrier became apparent that the islands were not wave action and longshore currents. islands that barrier islands are slimming eroding, but migrating, with shoreline erosion a part of the process.

16 Island migration involves three fundamental and eventually overrun by the moving processes: l) open ocean shoreline retreat, 2) islands. This sand, which often contains sound-side widening by overwash on the seashells of organisms that live only in the sound shoreline, and 3) raising the elevation sound (such as ), is contributed to of the island by overwash. the barrier island by a process described as The 1.5-meter contour depicted shoreface bypassing. Ocean side shoreline retreat is due to a is currently about number of factors, some of which remain 1.3-meters Through this process, old river or sound above mean sea unknown. These factors include a myriad of level, and is sand passes to the innermost continental human activities which effect sand supplies typically 90 cm shelf as the barrier island moves over it. plus the ongoing relative sea level rise. The above mean high Shoreface bypassing occurs mostly as a tide. Parts of the sound side widening process is carried on via area depicted in result of storm erosion of the shoreface. a number of processes. On Masonboro red will be above Between storms, waves gradually push the Island, storm waves from Hurricane Fran mean sea level newly churned up sand, complete with its for at least 100 washed over the narrow (less than 100 years and fossil shells, up to the beach. meters) island and deposited a series of sand probably 200 fans on the salt marsh behind the island, years. The 3.5- In some instances, particularly well meter contour thus widening the entire island in a matter of illustrates the illustrated on Cedar and Masonboro hours. Another widening process occurs area that might Islands, salt marsh muds that formed on the be flooded over a when inlets close. The flood tidal delta, the period of several sound side of the island crop out on the body of sand pushed into the sound by tidal beach. These occurrences, as well as the currents while the inlet existed, is built up ubiquitous presence of oyster shells on and attached to the island by the sediment many barrier island beaches, prove that accumulating ability of salt marshes or barrier island migration is for real. mangroves. If the inlet migrates, then the island is widened along the distance of inlet What does the mainland do while islands migration. This distance may be measured in are migrating? Needless to say, the miles in a time frame of a century or more. mainland shoreline must move back or the Figure 6 - Lands Vulnerable to Sea Level Rise islands will no longer be islands. In fact, A key element of island migration and As the islands migrated up the coastal plain once in a while the migrating islands do evolution is sand supply. Every grain of sand they left behind on the continental shelf a catch up with and smash into the mainland. on a barrier island came across the beach at blanket of sand that was once beach or island This is what has happened at Myrtle Beach, one time or another. Each grain came sediment. Thus a continuous supply of fresh SC. Here the mainland fronts the open onshore either by being blown there or by sand was needed to maintain the island. ocean. Given enough time and enough sea being washed there by storm waves and Geologists believe that this sand is obtained level rise, it is probable that the island will floods. by the continuous capture of former river break away from the mainland a few sand, once deposited at the heads of estuaries thousand years from now.

17 18 CHAPTER 2: Coastal Hazards and Hazardous Processes

The coastal landscape is an evolving, cyclones, and ongoing processes such as Hazardous Events dynamic balance between sediment supply, winds, waves and storm surge wave energy and sea level change. As more Hurricanes and northeasters have played and more people live and build in the coastal The term "natural" eliminates such important roles in the modification of the zone, the potential for property damage and manmade phenomena as war, pollution and shoreline. The present shoreline is, in fact, loss of life increases summarily from chemical contamination as well as hazards mainly the result of erosion and deposition hurricanes, nor’easters and even minor not necessarily related to the physical caused by these storms. A sever northeaster storms. environment such as infectious disease. or hurricane can cause as much of an impact to the shore in a matter of a few hours as it This section presents an analysis of the How Natural are Natural Hazards? would take normal weather conditions to natural phenomena that constitute hazards produce in a hundred years (LIRPB, 1984). along the North Carolina coast. The next Not withstanding the term "natural," a sections describe the geomorphologic natural hazard has an element of human Hurricanes and Tropical Storms features that influence the impacts that involvement. Without the human-built natural phenomena have on North environment to interact with, for example, Hurricanes are tropical depressions which Carolina’s coastal communities. coastal storms drive process that create and develop into severe storms characterized by shape the natural shore zone. winds directed inward in a spiraling pattern What are Natural Hazards? toward the center. They are generated over A physical event, such as a hurricane that warm ocean water at low latitudes and are A widely accepted definition characterizes impacts an undeveloped barrier island, that particularly dangerous due to their natural hazards as "those elements of the does not affect human beings is a natural destructive potential, large zone of influence, physical environment, harmful to man and phenomenon but not a natural hazard. A spontaneous generation and erratic caused by forces extraneous to him" (Burton, natural phenomenon that occurs in a movement. Phenomena associated with 1978). More specifically, the term "natural populated area, however, is a hazardous hurricanes include: hazard" refers to all atmospheric, hydrologic, event. A hazardous event that causes geologic and seismic phenomena that, unacceptably large numbers of fatalities • Winds exceeding 64 knots (74 mi/hr or 118 because of their location, severity and and/or overwhelming property damage is a km/hr). Hurricane damage results from the direct frequency, have the potential to adversely natural disaster. impact of wind' on fixed structures and from affect humans, their structures and their wind-borne objects (See Appendix I for more activities. Natural coastal phenomena information). include periodic extreme storm events, such • Heavy rainfall that commonly precedes and as hurricanes and severe mid-latitude follows a hurricane for up to several days. The

19 quantity of rainfall is dependent on the amount of moisture in the air, the speed of the hurricane's movement and its size. On land, heavy rainfall can saturate soils and cause flooding due to excess runoff (land-borne flooding) and damage crops by weakening support for the roots. North Carolina has experienced 275 tropical cyclone days (days that a storm has affected North Carolina) since 1800 (NWS, 2000). The total tropical cyclone days and percentage of occurrences by month is presented in the table below.

June: 23 Tropical cyclone days 8.4% July: 16 Tropical cyclone days 5.8% August: 65 Tropical cyclone days 23.6% September: 103 Tropical cyclone days 37.5% October: 62 Tropical cyclone days 22.5% November: 5 Tropical cyclone days 1.8% December: 1 Tropical cyclone days 0.4 % FIGURE 7 Tropical Cyclone Days and Percentage of Occurrences By Month

(Note that 81.1 % of the tropical cyclone days occurred from mid August through October. See Appendix II for more information).

Mid-Latitude Storms (Extra-Tropical Cyclones) Mid-latitude storms (often called nor’easters) are low pressure systems with associated cold fronts, warm fronts, and occluded fronts that typically cover larger areas, have much lower wind speeds and move slower than urricanes. Mid-latitude storms sometimes remain off the coast for several days. Unlike fast-moving

20 hurricanes, the winds and waves of a mid- Coastal storm processes rarely act separately. transporting sediment onto and off a barrier latitude storm may persist through several Wind, waves and currents can all be active at island. tidal cycles, amplifying shoreline impacts the same time and combine to form due to waves at any given location. secondary processes. For example, storm Hurricane winds are generally categorized in surge is formed by several processes acting terms of the pressure they exert. Pressure Mid-latitude storms get their energy from together, any one of which may be dominant varies with the square of the velocity of the the horizontal temperature gradients that during any given storm or for a given period wind and a doubling of wind velocity exist in the atmosphere. The ideal breeding during a certain storm: wind and waves push corresponds to a four fold increase in grounds for a mid-latitude storm are coastal water toward shore, low pressure allows pressure. For example, a 50 mph wind exerts areas where a large wintertime temperature doming of the sea surface and rotating winds a pressure of about 10 psf (pounds per difference may exist between air over the can cause shallow near shore water to flow square foot) on a flat surface. A 100 mph cold continental land and the relatively unpredictably. wind would exert a pressure of 40 psf, and a warmer ocean waters. The key to a low 200 mph wind would exert a pressure of 160 pressure center growing into a full-fledged Because hazardous events produce the psf (Pilkey, 1996). mid-latitude storm is the front (temperature processes which impact coastal communities; gradient) between polar air from the north it is the processes – and not the events The areas impacted by hurricane-force winds and tropical air from the south. themselves – to which coastal communities are usually within 20-30 miles of the track of are vulnerable, and which coastal hazard the eye. Considering that the diameter of a The presence of a strong high pressure mitigation strategies must address. hurricane ranges from 60 to 1,000 miles, system in eastern Canada can block a and that gale-force winds may extend over nor’easter from moving quickly up the East Wind most of this area, the total energy released Coast, giving a storm more time to gather The most common and, often, most costly over the thousands of square miles covered strength (Pilkey, 1998). hazardous coastal process is direct wind by the storm is almost beyond impact on structures, including flying debris comprehension. Considering their size, number and (known as missiling). Strong winds can also duration, mid-latitude storms pose a serious destroy vegetation by uprooting and Hurricane damage (experienced along the threat to barrier island development. knocking over trees, defoliating trees and US mainland) does not increase linearly with other vegetation, blowing down shrubs and wind speed. Rather, damage increases Hazardous Processes grasses and by damaging leaves directly - exponentially with wind speed, and a 148 either by blasting leaves with airborne sand mph hurricane (category 4 on the Saffir- Most, but not all, potentially hazardous and/or by carrying damaging salt spray Simpson Scale) may produce - on average - coastal processes are associated with inland (the same salt spray pruning effect up to 250 times the damage of a minimal hazardous events. The most important that produces the near-shore sloping profile category 1 hurricane (Pielke and Landsea processes that impact North Carolina are of maritime vegetation will kill or damage 1998). wind, waves, coastal and inlet currents, inland vegetation that is not salt tolerant). storm surge flooding and storm surge flood Storm winds can also be responsible for and ebb currents.

21 Waves of a hurricane. A 10-foot wave can exert Although storm surge is caused by strong Waves can damage property by direct attack more than 1,000 pounds of pressure per on-shore winds and/or intense low pressure or by pummeling structures with floating square foot, and wave pressures higher than cells and ocean storms, storm characteristics debris (a process called ramrodding). 12,000 psf have been recorded. alone do not determine storm surge elevations. Water level is controlled by a Depending on the track of a given storm, Storm Surge complex combination of wind, atmospheric waves can approach the coast from almost A storm surge is an abnormal rise in sea pressure, existing astronomical tide, waves any direction. If a storm passes along the water level associated with a hurricane or and swell, local coastal topography and coast, or at a low angle to the coast, the other storm at sea. The term “storm surge” is bathymetry and the storm's proximity to the time-averaged effect means that each point technically defined as “the super-elevation of coast. along the coast will be subjected to the same the still-water surface that results from the forces. The maximum height to which wind- transport and circulation of water induced by Together, these factors create a mound of generated waves will grow is controlled by wind stresses and pressure gradients in an water, the crest of which lies to the right of three factors: atmospheric storm” (Pilkey, 1998). the hurricane center near the position of maximum winds. The most common

impacts associated with storm surge include: 1. Velocity of the wind, A rule of thumb is that a 1 millibar change 2. The area expanse over which the wind blows in air pressure translates into a change in sea • (fetch) and level of about 1 centimeter. While this may Wave impact and the physical shock on objects associated with the passing of the wave front. 3. Length of time the wind blows. not appear to be significant, it is important to understand that a Category 5 hurricane • Hydrostatic/dynamic forces and the effects of The wave height limit is essentially the can have a central pressure of less than 920 water lifting and carrying objects. extent to which energy from the wind can be millibars - almost 100 millibars lower than transferred by friction to the water surface. Indirect impacts include flooding and the normal atmospheric pressure of 1,013 undermining of major infrastructure such as In the relatively simple case of a major millibars. This difference means that almost winter storm, the long fetch (hundreds to highways and railroads. one full meter of storm surge can be due to over a thousand miles) and duration (up to atmospheric pressure differences as a storm’s several days) means that the maximum wave eye crosses a shoreline. Storm Surge Ebb Flow heights for that given wind speed will The counterclockwise circulation in tropical develop. This condition is called a fully Storm Still-Water Surge Levels (in Feet Above cyclones is responsible for abrupt changes in developed sea. Mean Sea Level) for 25-, 50- and 100-year Storms wind direction and intensity during storm 25 50 100 passage. As a storm passes landward across a Virginia to Cape Hatteras 7.43 8.20 8.80 The force of a wave may be understood by Cape Hatteras to Cape Lookout 7.10 7.63 8.00 barrier coastline, this circulation pattern considering that a cubic yard of water weighs Cape Lookout to New River Inlet 7.63 9.33 10.95 produces abnormally high water-level more than three-fourths of a ton, about New River Inlet to Cape Fear 8.80 10.55 12.05 differences between ocean and sound. 1,500 lbs. Because a can move Cape Fear to South Carolina 9.67 11.23 12.45 shoreward at a speed of 30 or 40 mph, waves Note: “still-water surge level” is the height to For a hurricane moving perpendicular to the can be one of the most destructive elements which the sea rises during a storm, and does not Atlantic coast toward a barrier coastline, the include the height of waves.

22 initial winds of the storm are onshore to Rain (Falling/Rising Water) Currents alongshore. Elevated water levels occur along On an undeveloped barrier island, rainwater Storm-generated currents are responsible for the front of the barrier and on the mainland generally seeps into the ground or drains moving vast amounts of sediment, water and side of the sound. After passage of the storm toward open water. As an island is developed storm debris both parallel and perpendicular center, an offshore wind will result to the left and land is covered with buildings and to the coast. By far, the greatest volume of of the eye and an alongshore wind to the pavement, the amount of permeable land water during a storm is moved alongshore as right of the eye. surface exposed to absorb rainfall is reduced, storm waves approaching the shore at an and runoff increases. On barrier islands with angle set up a current in the general If the forward motion of the storm is rapid, dense urban development, or areas where the direction of wave travel. This phenomenon reversal of wind direction is abrupt, giving contour of the land has been altered, storm is known as a longshore current. Storm rise to abnormally high storm-surge ebb runoff does not follow the natural course currents are often reinforced – or diminished against the back side of the barrier island at and can create a washout resulting in – by wind friction. the same time sea level on the ocean side is flooding of shorefront property. In addition, low as winds push the water seaward. These the washout exposes land and buildings Because storm waves are so large, they begin conditions lead to flood flow across the behind the dunes to further flooding by to break much farther from shore than island in the seaward direction, resulting in storm surge. normal or fair weather waves. The net effect erosive scour and the potential for is a widening of the surf zone. When the surf formation. zone is widened, more sand is forced into the Shoreline Movement Changes in shoreline position result from water column and more water and sand is Storm surge ebb is not a dominant process moved parallel to shore. A strong longshore in all hurricanes, but its intense scouring beach-ocean interaction coupled with human activity. Wind, waves, and longshore current can move sediment (and storm during Hurricane Hugo, for example, was debris) out of one local area and into responsible for significant property damage currents are the driving forces that determine shoreline position, and the removal and another, resulting in a permanent loss of to buildings, seawalls, roads and utilities. sediment. Ebb scour channels, eroded through deposition of sand permanently changes beach shape and structure. During a storm, washover deposits, indicated that the process Storms are also responsible for a variety of was separate from, and took place after, the sand may be transported to land-side dunes, deep ocean trenches, other beaches and deep bottom currents that move at high angles, erosion and deposition induced by storm sometimes perpendicular to the shoreline. surge and waves. ocean bottoms. Bottom currents are due to the local rise in sea level caused by the storm surge. Because Surge elevations and ebb flow velocities are A migrating shoreline poses many problems for a coastal community in that property is surge sets up a sea surface that is actually influenced by several factors including the tilted away from land, the water above shape of the ocean or estuarine shorelines frequently lost to the dynamic beach-ocean system. Additionally, human activity may normal sea level tends to flow “downhill” (concave or convex), the presence or absence and back out to sea. of estuarine vegetation, wind speed, storm accelerate the process of coastal erosion through poor land use decisions. duration and the direction of storm movement.

23 Bottom currents, while not usually very strong or common, can be responsible for moving great quantities of sediment in short periods of time away from the beach and into deeper water where it may be permanently removed from the beach system.

Inlet Dynamics Currents and patterns of flow (channel positions) in tidal inlets may be modified by the combined effects of storm surge, stage of tidal cycle, increased rainfall runoff and ebb scour.

Changes in channel positions during storms may cause erosion of, or deposition on, adjacent islands.

To understand how hazardous coastal events impact coastal communities, we must first understand the interactions between natural processes, , their sediments and vegetation; and then the mechanics of the Figure 8: Storm Overwash from Tropical Storm Dennis Between Two Buildings in Kill Devil Hills, NC actual event.

24 CHAPTER 3: Coastal Hazard Geoindicators

No locality along the coast is truly safe. section discusses how PSDS uses these auditing and monitoring, or for initial Hurricanes, floods, wind, waves, erosion and geoindicators to assess coastal vulnerability. coastal assessment as in developing countries. inlets can impact any community. In addition, human activity almost always Geoindicators Most geoindicators are best evaluated in the reduces the relative stability of the natural field, although much information may be environment. The International Union of Geological drawn from other existing sources such as Sciences (IUGS) defines geoindicators as maps, orthophotographs, videos and erosion Human-built structures are static, and when “measures of surface or near-surface rate documentation. Using examples of placed in a dynamic system, they tend to geological processes and phenomena that barrier and mainland coasts, indicators of disrupt the balance of that system. vary significantly over periods of less than process/response are examined regionally, Interference with sand supply, the disruption 100 years and that provide information that locally and site-specifically: the latter being of vegetative cover, topographic alterations is meaningful for environmental assessment” the primary influence upon individual and the effects of other structures can (Bush, 1999). properties. actually create conditions that increase vulnerability. Berger notes that geoindicators identify a Natural Clues to Vulnerability minimum set of parameters that describe The concept that different parts of a short-term environmental dynamics and are Coastal geomorphology is controlled by a community respond differently to similar proxies representing all the parameters on wide range of geologic and climatic factors coastal processes is fundamental to the which processes depend. As a result, and processes operating at a variety of scales. development of an effective hazard geoindicators can provide managers with The frequency, intensity and location of mitigation strategy. While many natural simple, qualitative tools for rapid active physical processes (and events) are events and processes are potentially identification of vulnerability that is controlled by regional factors (seismic setting hazardous to development along the North scientifically valid (Bush, 1999). and latitude), local factors (protective Carolina coast; the type, extent and degree of offshore barriers and coastal configuration) impacts that these processes will have are Coastal geoindicators are geomorphologic and site-specific factors (elevation and dictated by a set of local geologic, features that influence coastal processes and vegetation). Geoindicators tend to focus on environmental and morphologic features determine how a community will respond the local and site-specific factors that show collectively known as geoindicators. to, and recover from, different coastal the less-than-100 year variation. processes. Because of their role, geoindicators This section provides an overview of the provide a management tool for the A number of environmental features provide most common types of geoindicators found assessment of vulnerability and risk, either as clues to a community’s active physical along the North Carolina coast. The next a supplement to long-term environmental processes, its natural history and associated natural hazards. A critical observation of

25 each feature can help assess the relative reducing the intensity of various coastal The specific critical elevation will vary intensity of various processes that have acted processes and vulnerability. An embayed between locations depending on regional in the past and, therefore, provide an coast, for example, may be somewhat flood experience and predicted levels of indication of the level of vulnerability protected from intense wave attack during a storm surge. associated with development in a storm, although storm surge flooding may be community. magnified as surge waters are funneled up Vegetation the embayment. A convex coast, on the Vegetation has a significant influence on Regional Factors that Determine other hand, is not at risk for storm surge coastal processes. Vegetation, for example, Vulnerability amplification although it is likely to traps sediment, stabilizes barrier islands and experience focused wave energy. A quick look at a coastal community’s coastlines, provides a protective barrier regional geologic and oceanographic setting against wind, stimulates growth of certain can give insight into the types of processes Local Factors that Determine dune grasses and can decrease storm surge that should be active in an area. The regional Vulnerability and ebb flow velocities. The presence of setting, in part, determines vulnerability. Site-specific factors are the primary well-developed areas of shrubs and trees, indicators of the hazards likely to impact a especially high on the backshore of a beach, For example, latitude will determine some community. The shoreline type existing in suggests low erosion potential and infrequent climatic and oceanographic factors such as any particular area is a function of rock or salt water intrusion. wind and wave patterns, currents and sediment type, the landforms being susceptibility to hurricanes. The deposited or eroded by the waves, their Grasslands oceanographic setting of the adjacent storm response, the dominant direction of Grassland are located behind the continental shelf and regional coastal wave approach, wave heights, elevation and dune . It occupies areas that are configuration will influence the distribution human influence. Geoindicators are divided moister and lower than the dunes. The of energy reaching a shoreline (narrow into four groups: 1) topographic, vegetation consists primarily of grasses, shelves allow more wave energy to reach a 2) shoreline, 3) inlet and 4) other. sedges and occasional shrubs. Grasslands are coast, but a wide shelf may increase the rarely flooded by tidal water although high spring or wind tides may flood from the potential elevation of storm surge flooding). Topographic Geoindicators sound side. Most grassland plant species are The presence of local natural offshore Elevation able to survive short periods of salt water flooding. features such as sand bars or reefs may Site elevation is a primary determinant of dissipate wave energy and afford some susceptibility to inundation. Elevation above The dominant grass and sedge species in natural protection. The geologic setting will sea level and elevation above ground level are grassland ecosystems include salt meadow determine whether shorelines are rocky and also important determinants of vulnerability cordgrass, little bluestem, muhly, bulrush, resistant or are composed of unconsolidated, because they have a direct influence upon Fimbristylis, finger grass and love grass. erodible material. wave action, storm surge and storm surge Important broadleaf species include ebb flow. pennywort, Sabatia and seaside goldenrod. The configuration of the shoreline can also play an important part in increasing or

26 Shrub Thicket Dune Escarpment Narrow, steep shelves - such as that found Shrub species such as wax myrtle, marsh In most cases, the shoreline is the least stable off Cape Hatteras, North Carolina – do not elder and sea ox-eye usually invade areas component of the coastal environment and hold much water and will not allow storm where vegetation has been established for a receives the greatest management attention surge to pile up. As a result, locations with long period of time. These areas may because of potential real estate loss and steep, narrow shelves have inherently lower eventually form a dense thicket of shrubs property at risk located near the shoreline. maximum potential surge elevations than and even a maritime forest. The thickets may Although some shorelines are stable, broad shelves. A steep, narrow shelf, be impenetrable or scattered. Shrub thickets erosional shorelines are more common. The however, produces less frictional dampening grow on the edges of maritime forests, on rate at which an ocean or estuarine shoreline of wave energy, which means more wave old stabilized dunes and in dune swales. In is eroding - or accreting - is an indicator of energy is expended on the upper shoreface. closed thickets, the ground is nearly barren vulnerability because it illustrates whether of herbaceous vegetation due to the lack of sediment is being lost from, or added to, a In general, wide shelves mean higher light penetration. Within more open shoreline over time. maximum tidal amplitudes and lower wave thickets, grassland vegetation or black energy. On narrow shelves, the opposite is needlerush marsh may be interspersed Long term average erosion rates may fail to true. among the patches of shrub. illustrate acute, and often significant, changes caused by individual storm events. Water Exposure Post-storm field assessments are used to help Shoreline Geoindicators The area of open water a shoreline faces, or document these changes. During storms, fetch, partly determines the size of storm ancient strata that crop out on the shoreface Dune Parameters waves that may be experienced. The greater are eroded, providing an immediate source The ability of a frontal or primary dune to the fetch, the larger the wave-making of “new” sediment to the modern beach. absorb incoming wave energy is directly potential. In mesotidal barrier-island Therefore, the composition of most beaches related to the dune’s height and width. systems, back-barrier tidal creeks and reflects the composition of ancient sediments High, continuous, heavily vegetated sand channels often erode the backside of a barrier eroded from the shoreface. dunes at the back of the beach are evidence island as fast as open-ocean waves erode the of a stable or accretionary shoreline. Bare front side. North Carolina shorelines erode primarily scarps at the back of the beach indicate very because the supply of new sediment is not recent wave or storm surge erosion, and Beach Width dune protective capability is reduced until sufficient to replace what is removed, and sand accumulates and dunes are rebuilt. because sand transport mechanisms are being The width of the dry beach at high tide is Dune breaches, breaks and gaps, such as altered by such human activities as dredging. another measure of vulnerability. A flat those cut to allow for emergency vehicle beach, often found after a storm, can be access, will decrease the natural protective Bathymetry explained in terms of the dynamic equilibrium. An increase in wave energy, features of a dune. Bathymetry, or the nature of the offshore along with a rise in sea level associated with continental shelf, has an important influence storm surge, moves sand and changes the on storm surge elevations and wave action.

27 shape of the beach. Departing storm waves take sand from the upper beach or from the first dune and transport it to the lower beach.

In North Carolina, most beaches respond to a storm by flattening, which causes storm waves to expend energy over a broader and more level surface. In a major storm, the surf zone sand is sometimes transported beyond the base of the shoreface and is lost from the beach forever, and an island can lose a great deal of sand during a storm. Sand that remains in the shoreface system can, however, return as it is gradually pushed shoreward by fair weather waves. Due to the presence of longshore currents - produced by waves that approach the shore at an angle, sand may be deposited miles from where it was originally removed. Nourished beaches, and those with engineered structures such as sea walls and revetments, generally recover much less sand than natural beaches.

Generally speaking, a dry beach width of at least 20 feet is needed to dissipate and reduce incoming storm wave energy.

FIGURE 9 Storm Overwash When the height of approaching storm waves exceeds the height of depressions along the dune ridge, water overflows the low points and washes down the landward side of the dunes, eroding sand and carrying it inland.

28 These washover areas deepen and widen Overwash fans develop when water thrown Washouts may also be formed by retreating under continual wave attack, allowing larger up by waves and storm surge flows between sound waters. Hurricanes, particularly slow- volumes of water to spill across the dune line and around dunes. Surge waters carry sand moving ones, may pile water into the and flow farther inland. Eroded sand may be and stained, bleached and natural-colored sounds. If natural channels such as inlets are deposited behind the dunes or carried into shells that are deposited in flat, fan-shaped too narrow to accommodate water retreating the middle of the island. In very severe masses. Sand from these fans forms and from the sounds, washouts may cut across storms, washover waters may even reach the maintains dunes and builds island elevation. the low areas of least resistance in the barrier back side of the island. When overwash fans are extensive, they may islands. overlap and form sheets called overwash Storm Overwash: terraces. Blowouts are breaches in the dunes caused Storms may also produce washouts in dune by wind erosion. They are usually aligned areas. These are similar to washovers, with prevailing northeasterly winds and may differing primarily in the direction of be cut down to the water table. During eroding waters. If there are breaches or storms, blowouts may become channels for depressions in the dunes, rainwater that storm-surge waters from the sounds. collects in the swales (valleys between the dunes) may be channeled through these low The presence of overwash fans, overwash points and overflow back onto the beach, aprons, overwash terraces, washouts and carrying sand with it. How a washout forms: How a blowout forms:

Areas of frequent major washovers may regenerate dunes slowly due to the volume of sand removed through erosion and because vegetation has been scoured.

Dune development may be impeded if the sand in a washover is too wet to be blown by the wind. Evidence of hurricane washovers is apparent on many North Carolina barrier islands.

29 blowouts indicate active sediment transport Barrier islands, particularly low areas in inlet closed are almost always unstable areas for and deposition. These features are used to zones, are often breached by mall channels development. Some inlets that have closed help assess historic storm impacts and during storms, either by storm-surge flood, naturally, however, may be relatively safe predict future responses. or more often, by strong storm surge ebb because a tidal delta may have increased the flow. These channels are not technically island's width enough to promote dune and Engineering Structures considered inlets because they develop and vegetation growth. The presence of an engineered structure such exist only long enough to facilitate interior as a revetment, sea wall or groin indicates island drainage. Although these features are Non-Shoreface Geoindicators that a particular stretch of shoreline is likely usually temporary, they tend to re-appear in Barrier island features such as sand volume, being negatively impacted by one or more the same location. soil type and the presence of black-stained processes. shells are all indicators of vulnerability. Inlet Proximity Interior dunes, for example, provide Once formed, inlets tend to migrate laterally Inlet Geoindicators protection from storm surge flooding and along adjacent barrier islands. waves, and can act as a shield against Inlets are highly dynamic features and can Potential Inlet Formation damaging winds. Black-stained shells, which influence shorelines some distance away. Low, narrow island areas that lack extensive are characteristic of estuarine and back-island salt marsh and are near the mouths of rivers environments, may mean that an inlet was or estuaries are likely spots for inlet Historic/Relict Inlets artificially filled with sediment dredged from development. Spits are particularly The presence of a flood tidal delta can behind the island (Pilkey, 1998). vulnerable to inlet formation. indicate the location of an inlet that is now closed. Inlets that have been artificially

30 CHAPTER 4: Assessing Coastal Vulnerability

The first step in the hazard mitigation hazards to exist where none existed before. STEP 1: Acquire Data process is to identify the natural processes For example, an interior sand dune removed present, or that may affect, the study area. for development reasons can reduce a barrier The first step in the PSDS Vulnerability This information can be obtained through a island's elevation and increase the likelihood Assessment Methodology is the acquisition comprehensive literature review, through for overwash and possible inlet formation. of relevant data. Existing GIS layers were interviews with residents, state and local Another example is shoreline migration. acquired (A) and additional layers developed decision makers and others and through Shoreline migration is a natural processes (D) using data collected with a Trimble investigator knowledge and experience. This that only becomes a hazard – called erosion - GeoExplorer II hand-held Global last element is extremely important because a when houses and roads become threatened. Positioning System (GPS) unit. GPS significant portion of the hazard technology was utilized to ensure the identification and vulnerability assessment is Human intervention can also reduce the positional accuracy of spatial data. The subjective. mitigating effect of natural ecosystems. The standards of quality required of the data and destruction or removal of native island the methods used to measure quality were Vulnerability is defined as “being open to vegetation, which has been shown to reduce explicitly defined before data entry begins. attack or damage.” Because human coastal wind velocity and water flows, can eliminate development can be attacked and damaged a barrier island's primary protective resources • Hurricane Storm Surge Inundation Areas by a variety of natural processes and events and is a clear example of an intervention that • Q3 FIRM data (A) (such as hurricanes and tropical storms), it is diminishes the ability of an ecosystem to highly vulnerable. However, where no protect itself. • LIDAR elevation data (A) human interests exist, these same natural • Beach access sites (A) phenomena do not constitute hazards nor do Although humans can do little, if anything, they result in disasters. The definition of to change the incidence or intensity of most • Population and housing variables (including vulnerability is, therefore, at odds with the natural phenomena, we can play an mobile homes) (A) perception of natural hazards as unavoidable important role in ensuring that these natural • Public water and sewer systems (A) havoc wreaked by the unrestrained forces of events do not become natural disasters. • nature. Further, it shifts the burden of Transportation routes (A) “causality” from purely natural processes to This section provides an overview of PSDS’ • Average long-term annual erosion rates (A) the concurrent presence of human activities vulnerability assessment methodology and • and natural events. outlines how geoindicators are used to Frontal dune configuration (height, width and measure, assess and delineate vulnerability in distribution) (D) Unfortunately, human activities along the coastal communities. • Beach characteristics (swash zone width and coast tend to increase the frequency and slope) (D) severity of natural hazards, or cause natural

31 • Modern inlet dynamics (D) for each community. Maps were analyzed to low) depending on how much influence a identify specific locations that are more specific geoindicator to different physical • Historic storm responses (D) susceptible to the impacts of a category three settings found in the community. • Vegetation distribution, density and type (D) hurricane, and that may be priority areas for • Engineered erosion management structures (D) hazard mitigation activities. Hazard geoindicator attributes are ranked as being high, moderate or low - in terms of • 10, 30 and 60 year shoreline positions Because vulnerability maps are based on how much influence the hazard geoindicator • Structure and parcel tax and value data (for semi-quantitative data, the incorporation of has on coastal storm processes - with points Ocean Isle Beach and Nags Head) specific attributes is largely subjective, and associated with each ranking (10 for high quantitative limits for determining absolute hazard, 5 for moderate hazard and 1 for low • Hurricane Storm Surge Inundation Areas parameters such as dune height, beach width hazard). • Q3 FIRM data and vegetative density are determined individually for each community. The Vulnerability Matrix • Beach access sites After the Hazard Profile is completed, a • Population and housing variables (including STEP 3: Vulnerability Assessment Vulnerability Matrix (page 10) is developed. mobile homes) The Vulnerability Matrix is used to PSDS has developed a Hazard Profile and determine the relative importance that each • Public water and sewer systems Vulnerability Matrix that incorporates GIS hazardous event, natural process and map data and observational information to • Transportation routes Geoindicator has on the vulnerability of the help delineate, assess and rank relative levels structure, as well as the overall vulnerability of vulnerability. Although vulnerability of the structure. Digital hazard/vulnerability maps are then assessments are performed on a community- developed using Arc View 3.2 GIS software. wide basis, special consideration is given to The Vulnerability Matrix is divided into Special attention is given to the the presence of local, site-specific four Geoindicator Categories (Topographic, identification of historic inlet sites, narrow geoindicators such as historic inlet sites, Shoreline, Inlet and Interior) that are beaches, overwash fans and aprons, storm narrow beaches, overwash fans and aprons, ranked, or weighted, based on the influence surge ebb and flow channels, inlets and dune storm surge ebb and flow channels, inlets that the planner (or other expert) feels each gaps. and dune gaps that can alter natural has on the overall vulnerability of the processes. structure. The sum of the scores must equal STEP 2: Data Analysis one, and the relative difference among scores GIS data layers were evaluated to identify The Hazard Profile reflects the relative weight or influence of the geographic location and spatial The Hazard Profile (next page) contains a each Geoindicator category. distribution of hazard geoindicators, and to list of all potential hazard geoindicators, with delineate vulnerability in each community. each geoindicator divided into two or three The Geoindicators comprising each of the Maps that illustrate risk - or the impacts that measurable attributes (depending on the four Geoindicator categories are then can be expected from a direct hit from a specific geoindicator). Each attribute is weighted. Again, the sum of the scores of category three hurricane – were developed assigned a hazard level (high, moderate or each Geoindicator - within each

32 Geoindicator category - must equal one with normalized weight representing the overall structure’s Hazard Attribute score to obtain the relative difference among the scores influence of each Geoindicator. a Final Score. The sum of the Final Scores is reflecting the relative weight, or influence, of the vulnerability of the structure. In this each Geoindicator within each category. Next, the structure’s Hazard Attribute scores example, the structure received a score of are transferred from the Hazard Profile into 7.78, which means the structure is Extremely The weight of each Geoindicator category is column eight (entitled “Score”) of the Vulnerable. then multiplied by the weight of each Vulnerability Matrix. Each Geoindicator’s individual Geoindicator to arrive at a normalized score is then multiplied by the Because the weighting process is based upon semi-quantitative data, the incorporation of specific attributes is largely subjective, and quantitative limits for determining absolute parameters such as dune height, beach width and vegetative density must be determined individually for each structure or community.

A Hazard Profile and Vulnerability Matrix can be developed for a street, neighborhood and possibly even an entire barrier island, depending on the objectives of the project. It is important to point out that different Hazard Profiles and Vulnerability FIGURE 10 Matrices must be created for different coastal settings, and the results of a vulnerability assessment in one setting will be different, and therefore cannot be compared, to those obtained in another setting

National Assessment of Coastal Vulnerability to Sea-Level Rise: Preliminary Results for the U.S. Atlantic Coast

U.S. Geological Survey Open-File Report 99-593 E. Robert Thieler and Erika S. Hammar-Klose Woods Hole, Massachusetts 1999

33 34 CHAPTER 5: Coastal Hazard Mitigation

No locality on a barrier island is truly safe. arrangements necessary for mitigating integrates many aspects of the community's Hurricanes, floods, wind, waves, erosion and hazards. For small communities, non- natural environment. inlets can all attack any part of an island. In structural mitigation measures may be the addition, human activity only affordable alternative. Accepting Change always reduces the relative Apart from the loss of life and the Before a barrier island, or any coastal, stability of the natural property damages suffered by The work of PSDS is focused community, can develop an effective hazard environment. Human-built individuals, the most striking upon helping coastal counties mitigation plan, it must acknowledge, structures are static, and aspect of the storm’s effects on and communities identify understand and embrace one fundamental when placed in a dynamic Brunswick County shores was the hazards and reduce their rule: that change, the only constant within system, they tend to disrupt absolute totality of the damage vulnerability to these hazards. the balance of that system. and its implications with respect to the dynamic coastal environment, is both Interference with sand storm damages under conditions The methodology employed inevitable and unpredictable. supply, the disruption of of dense development. In this by PSDS involves geologic vegetative cover, topographic connection, there was hardly a and environmental While inland communities may be subject to alterations and other effects vestige of human habitation on principles, decision theory, periodic storms of such magnitude and of structures can actually the Brunswick County shore systems analysis and duration as to warrant caution and create conditions that following the storm…In view of observational inferences and preparation; tides, waves, inlets, currents, increase the vulnerability of a the severity of tides and waves takes a "process-oriented- beaches and dunes are in a relentless state of structure. attendant with Hurricane Hazel, it perspective" towards hazard flux along our barrier islands and, as a result, is reasonably certain that, had mitigation. In so doing, are constantly changing the composition, The high density of development been complete in PSDS links the quality of structure, character and stability of the population and expensive the area, it would also have been human life to environmental communities situated on them. infrastructure of developed totally destroyed. quality. communities makes them The coastal community courageous enough more susceptible to the -- US Army CorCorpsps of In a general sense, this effort to acknowledge, plan for and adapt to the impacts of natural events. EngineersEngineers ReReportport on Coastal may be considered changes that lie ahead will put itself in a Therefore, mitigation High Hazard Zones, 1975 "environmental planning" position to coexist in harmony with nature. measures are more critically because it consists of The community that chooses to ignore, needed and more amenable diagnosing the needs of a rather than accept, change will ultimately be to economic justification in developed areas community and identifying the resources relegated to fighting a futile battle against, than in less-developed areas. In addition, available to it, then using this information to the forces of nature. urban areas are more likely to have, or are formulate a hazard mitigation strategy that able to establish, the institutional

35 The Basics of Hazard Mitigation among living things and their environments. situations when tremendous pressures are In the context of economic development, the brought to bear on local, state and national While the preferred mitigation option is to environment is that composite of goods, agencies to replace - frequently on the same avoid hazards and the most vulnerable services and constraints offered by site - destroyed facilities. It is at such times locations, this option is not widely surrounding ecosystems. that the pressing need for natural hazard and achievable in North Carolina where many risk assessment information, and its coastal communities have already reached, or A barrier island beach, for example, is a incorporation into the development will soon reach, full development potential. natural ecosystem that provides no material planning process, becomes most evident. Therefore, to effectively mitigate coastal benefits except for panoramic views. The hazards in North Carolina, specific actions beach, however, provides storm protection, The Nature of the Planning Area must be incorporated into the various stages habitat and recreation. The beach, of the integrated hazard mitigation planning like any physical resource, also has its The physical characteristics of the land, land- process. constraints. It is dynamic, subject to storms, use patterns, susceptibility to particular waves and storm surge and is vulnerable to hazards, income level, and cultural This means that initial preservation of short and long term erosion. These characteristics are all considerations when natural environments, better recognition of vulnerabilities, or naturally hazardous developing a local hazard mitigation plan. coastal processes, conservation of sand and processes, constrain the development vegetation, recognition of the impact of potential of the ecosystem. A survey of environmental constraints, historical storms, post-storm redesign of whether they are part of an ocean, estuarine, compatible development, augmentation and Economic development projects, if they are maritime forest or inlet ecosystem, should “repair” of coastal environments to enhance to be sustainable, must incorporate sound include: or restore protective capabilities of the environmental management. By definition, natural setting and public all need this means that they must be designed to 1. the nature and severity of resource degradation; to be the basis for an aggressive and effective improve the quality of life and to protect or 2. the underlying causes of the degradation, such as the impacts of both natural phenomena and human mitigation strategy. restore environmental quality at the same use; and time and must also ensure that resources will not be degraded and that the threat of 3. the range of feasible economic, social, institutional, Mitigation and the Environment natural hazards will not be exacerbated. In policy and financial interventions designed to When identifying hazards and assessing short, good natural hazard management is alleviate degradation. In this sense, natural hazards must be considered an integral aspect of vulnerability in a barrier island community, good development project management. the development planning process. the environment - the structure and function of the ecosystems that surround and support In high-risk areas, sustainable development is human life - represents the conceptual only possible to the degree that development The Hazard Mitigation Plan planning decisions, in both the public and framework. Ideally, a hazard mitigation plan promotes private sectors, address the destructive an awareness of the issues related to coastal potential of natural hazards. This approach is An ecosystem is a coherent set of development, evaluates the threats of natural particularly relevant in post-disaster interlocking relationships between and hazards, identifies the additional information

36 needed for a definitive evaluation and individual or governmental component, but Community Planners and State recommends appropriate means of obtaining should include the cooperation of many. Agencies it. Most local planners are unfamiliar with Post-disaster reconstruction activities often natural hazards information or how to use it The first step in developing a hazard lack support for a hazard assessment for hazard mitigation planning. State mitigation plan is an assessment of the intended to characterize potential hazardous agencies similarly have little familiarity with presence and effect of natural hazards in the events and ensure that the impact of the next natural hazard information or with the planning area. The second step involves an event is less destructive. Reconstruction techniques of adapting it for use in planning. estimate of the potential impact of natural projects, especially when they are very large, Projects for the development of roads, processes on development. The third, and are often managed by newly created energy, telecommunications or other final, step includes measures that reduce implementation agencies. This can result in infrastructure often lack hazard mitigation vulnerability in the plan area. a drain on the already limited supply of considerations. State agencies also tend to technical personnel from existing agencies have little experience in collaborating with A community-based hazard mitigation plan and complicates coordination between long- each other to identify the interrelationships may include detailed information on term development and short-term between projects or to define common possible mitigation alternatives including: rehabilitation. information requirements so that beneficial

information can be cooperatively collected. • Recommended geologic-based coastal hazard Mitigation Planning Participants mitigation alternatives Local Governments • Among the "actors" involved in the process How a recommended mitigation alternative will of hazard mitigation are local and state Although local communities are aware of the address a local hazard planning agencies, emergency management impacts of natural hazards, they usually have • The environmental impacts of the mitigation organizations, the scientific and engineering little opportunity to participate in the alternative community, technical assistance and support preparation of large infrastructure and agencies, non-governmental organizations • The costs associated with implementing the production projects that impinge on them, and private-sector players such as business mitigation alternative and even less in setting agendas for natural and homeowners. hazard assessment and vulnerability • Potential implementation strategies reduction. Special attention should be given to Because each entity has its own interests and redevelopment strategies including ongoing approach, these varied, and sometimes Federal Agencies redevelopment associated with continuing conflicting, viewpoints can add to the On a national level, giving a single entity economic and community development and constraints of planning and putting into total responsibility for hazard management the periodic window of redevelopment operation a hazard mitigation plan. Having tends to cause other agencies to see it as an opportunity associated with recovery from a advance knowledge of the difficulties each adversary. Instead, each agency that disaster event. At the individual project level, may present, however, can help the planner formulates projects as part of its standard responsibility for mitigating the impacts of deal with them. activities should appreciate the importance natural hazards should not lie with a single of introducing hazard considerations into the

37 process of planning. Agencies should, the needs of vulnerability reduction or agency such as a research university proposes therefore, take an advocacy position on emergency preparedness. For example, to incorporate ideas into planning and hazard management and on introducing valuable information on hazards is often project formulation, it invariably has to non-structural mitigation strategies early in published in scientific journals in abstruse overcome the skepticism of the relevant local the planning process. Such agencies should language. The scientific community should personnel. This adds to the cost of have personnel trained for these functions. ensure that data is translated into a form formulating a project, but the extra cost can suitable for use by hazard management pay high dividends. Emergency Management practitioners. The emergency preparedness community has Private Sector historically viewed its role exclusively as Disaster Management Agencies Greater consideration should also be given to preparing for and reacting to emergencies Most disaster support organizations engage the private sector. Claims have been made (although this is beginning to change). As a actively in post-disaster reconstruction that policy-makers can change social result, this group often fails to link measures, but do not insist on hazard behavior more effectively by changing the preparedness to long-term mitigation issues. assessment, mitigation, and vulnerability incentives of the marketplace, i.e., the public Furthermore, emergency managers often pay reduction measures, and are often reluctant use of private interest, than by regulation. insufficient attention to the vulnerability of to incorporate such considerations into their For example, casualty insurance companies their own infrastructure. ordinary (non-disaster-related) activities. could offer a large premium differential for hurricane-resistant construction. A Scientific And Engineering Community Technical Cooperation Agencies government agency could specify the desired The scientific and engineering community Knowledge of and experience with hazard outcome of a policy, but leave the method of often sets its agenda for research and management techniques are rare achieving that outcome to the economic monitoring on the basis of its own scientific commodities in most state and local actors. interests without giving due consideration to agencies. Thus, if a technical cooperation

38 CHAPTER 6: PSDS Coastal Hazard Mitigation Alternatives

PSDS has developed a comprehensive Dunes deposited as shallow offshore sandbars. In a catalog of geologic-based, non-structural stable beach-dune system, sand that is coastal hazard mitigation alternatives that Coastal barrier dunes are formed by wave moved offshore during storms is often may be used in both developed and and wind action. In North Carolina, waves returned during calm weather. Thus, the developing barrier island communities. This bring sand from the inner continental shelf dunes, beach, and near-shore sandbars act as section provides an overview of each to the shore where it is transported landward a dynamic, integrated unit which is often mitigation alternative including: by onshore winds. Obstacles such as referred to as the beach-dune system. driftwood, sand fencing or vegetation reduce 1. qualitative causal relationships with storm wind speed, causing sand to accumulate. As A detailed study of the South Carolina coast processes (how the mitigation alternative may sand accumulates, plants adapted to the after Hurricane Hugo concluded that the reduce or enhance a given storm process), beach environment emerge, stabilizing the minimum dune field that survived Hugo, 2. potential environmental impacts (whether the surface and promoting further dune and thus protected buildings, was 100 feet mitigation alternative will impair or improve formation. In the absence of stabilizing wide with dunes about 10 feet high. Most of environmental quality) and vegetation, blowing sand may drift into large the buildings damaged or destroyed by Hugo 3. long-term costs (whether the long-term costs of "live" dunes that move back and forth with were fronted by dune fields less than 50 feet implementation are high or low). the wind, such as Jockey's Ridge near Kill wide (Bush, 1996).

Devil Hills Hard stabilization alternatives such as Although dunes serve as temporary seawalls, revetments bulkheads and groins protective barriers during storm tides of The Beach-Dune System: are currently illegal in North Carolina and short duration, they are not effective against will not be discussed in this report. Functions, Values and Limitations persistent beach recession caused by rising Temporary erosion protection strategies such Dunes act as flexible barriers to ocean storm sea level, migrating inlets or changing as sandbags also will not be included in this shoreline dynamics. Therefore, they cannot report. surges and waves, protect low-lying backshore areas and help preserve the be considered permanent structures that will "hold off the ocean." Specific recommendations for each integrity of low barrier islands. In addition, they provide a habitat for many animals community are provided in Chapter 6 which The value of dunes and their fragile nature contains individual summaries for each of including migratory birds. are often misunderstood or not appreciated. the five model study communities. Excessive use often upsets the natural Dunes formed as a result of vegetation act as natural sand reservoirs for beach balance, damaging the vegetation and nourishment. During storms, sand that deteriorating the dune system. One of the erodes from the beach-dune system is often earliest uses of dunes in North Carolina that resulted in considerable damage was

39 overgrazing by cattle, horses and sheep. drought and a limited nutrient supply. Only that produces good results in the Carolinas. Today, shoreline development and the a few plant species can tolerate these stresses. Bogue is another selection being used in the pounding of dunes by feet and vehicles pose state. Cape, a northern strain that declines serious threats to dune vegetation and dune Dune Grasses rapidly after the first growing season, is not stability. Perennial grasses are the primary stabilizers recommended. Hatteras and Bogue are both of frontal dune systems along the North available from commercial producers. Intensive beach use increases the need to Carolina coast which is in a transition zone restore, construct, protect, and manage between the northern-dominant American Because American beachgrass is a cool-season dunes. With proper planning and beachgrass and the southern-dominant sea grass, the best planting dates are November management, however, dune functions may oats. Bitter panicum or "running beachgrass" through March. Plant small areas by hand be enhanced or restored. is also an important grass on frontal dunes in using a dibble to open a hole 1 inch in North Carolina. diameter and 8 to 10 inches deep. Pack sand Restoring Dunes firmly around the plants after they are placed American Beachgrass in the holes. Space the plants 18 to 24 inches Dune sands are readily moved and shaped by American beachgrass is a cool-season dune apart at the crest of the dune and increase wind and water action. Consequently, grass native to the North, Mid-Atlantic, and the spacing to 2 feet and then to 3 feet for disturbed dunes revert rapidly to unstable Great Lakes coasts. North Carolina is at the several rows on each side of the crest. conditions, regardless of their stage of southern end of its natural range. American development at the time of disturbance. beachgrass is a vigorous, upright grass that After establishment, American beachgrass grows in dense clumps and is capable of will grow through as much as 4 feet of sand As a result, dune restoration usually begins rapid lateral spread by runners. Hence, it is accumulation during one growing season. with the establishment of pioneer plants and widely used for initial stilling of blowing Although it grows quickly where sand vegetation is critical to dune formation and sand. It is easily recognizable by its dense, accumulates on the seaward dune edge, it stabilization. Without vegetation, blowing cylindrical spikes or seed heads. tends to die out behind the dune crest after sand will migrate inland. Several characteristics make American only a few years. This die-out is caused by beachgrass suitable for dune building and climatic effects, fungal disease, and insects. Dunes that are only slightly damaged may be stabilization in North Carolina: repaired by planting vegetation in bare areas, To further increase the diversity and stability giving stressed grasses a judicious amount of • Quick establishment and effective trapping of of the beach-dune system, sea oats and bitter fertilizer and protecting the area from sand the first growing season. panicum should be included in beachgrass trampling and traffic. plantings. • Ease of harvest, storage, and transplanting, with Selection of plant species is of paramount an excellent survival rate. Sea Oats importance when restoring vegetation in • Commercial availability from nurseries at a low Sea oats are a warm-season grass, native to bare areas of existing dunes. Dune plants cost. coastal dunes from the Virginia Capes to must be able to survive sand blasting, sand Mexico. The plant's striking appearance, burial, salt spray, saltwater flooding, heat, Recommended cultivars include Hatteras, especially in bloom or fruiting, has made Bogue, and Cape. Hatteras is a fine-leaf type legal protection necessary in some areas to

40 avoid excessive harvest. Due to an extensive inclusion in American beachgrass and sea and spacing are similar to those described for root system, sea oats persist both seaward of oats plantings to increase plant diversity. A American beachgrass. The best planting the dune and behind the dune crest. Other wide variety of species is available, with dates are March through May. characteristics include: variable stem sizes and growth characteristics. Although bitter panicum Planting a combination of several of these • Vigor and drought tolerance. grows and multiplies relatively well in field species can enhance the beach-dune system's nurseries, it is not as widely available as diversity and long term viability. • Effective trapping of sand. American beachgrass. Commercial • Low incidence of pests. availability is limited, and plants may have to Seashore Elder • Excellent persistence. be obtained by thinning local stands. Seashore elder, a low-growing woody shrub, Bitter panicum will root at each node on the also grows well on frontal dunes and may be • Tolerance to a limited supply of nutrients. stem, so it may be planted by placing transplanted to add diversity to the dune Planting stock may be acquired as seedlings runners in a trench 6 to 8 inches deep and system. Seashore elder spreads both by seed from commercial producers, or, with covering the runners with sand. Leave one and vegetatively as roots develop on stems permission on private property, transplants third of the upper shoot out of the ground. buried by sand. It adds diversity to the can be dug from existing stands. The best The best transplanting dates are March landscape and is useful for planting where transplants are 1- to 3-year-old seedlings through May. American beachgrass has died out. often found in small clusters seaward of the frontal dune. saltmeadow cordgrass Plants can be obtained by collecting and A fourth grass, saltmeadow cordgrass, rooting the cuttings, or rooted stems may be although not a true dune grass, often traps Although sea oats provide the best long-term dug from around existing plants. Seedlings sand to initiate dune growth. Saltmeadow stability, the grass does not spread as rapidly are often found around older plants and in cordgrass grows well in low, moist areas such as American beachgrass, and its slow lateral drift lines. Planting in early spring is usually as sand flats and high salt marshes and is spread results in steep dune slopes. It should the most successful. more salt- and flood-tolerant than the dune be planted in conjunction with American grasses. Saltmeadow cordgrass is useful for beachgrass or bitter panicum because of their planting in low areas subject to occasional Dune Construction/Repair more rapid spread and lower cost per plant. saltwater flooding during storms. Its range Planting methods and spacing for sea oats When barrier dunes are absent, or where includes all of the Atlantic and Gulf coasts of are similar to those described for American dune gaps are present, they may be rebuilt or the United States. Saltmeadow cordgrass beachgrass. Because sea oats are a warm- plugged by bulldozing, dredging or by often initiates new dunes on low flats that season grass, the best planting dates are trapping blowing sand with sand fences and may later become occupied by plants better March through June. vegetation. Building dunes with vegetation is adapted to dry conditions. more economical than using heavy

Bitter panicum equipment and discourages placement of the Bitter panicum or "running beachgrass" is a Seedlings are commercially available from dune too close to the ocean or in other warm- season grass found on dunes from wet- land plant nurseries. Plants can also be unsuitable locations. New England to Mexico. It is useful for obtained by digging from young open stands where plants are vigorous. Planting methods

41 Man-made dunes should be of the same Bulldozing planting shoes. Furrows should be 8 to 10 general height, slope, width, and shape as the Beach Bulldozing (or scraping) is a process inches deep and spaced at least 18 inches natural dunes in the vicinity. Generally, they in which a thin layer of beach sediment (one apart. Plants should be closely spaced, 18 should be no less than 4 feet high with a foot or less) is moved from the high tide line inches by 18 inches, in several rows where slope of no more than 45 degrees (a rise of 1 in an effort to reconstruct or repair frontal the crest of the dune is to be located. foot for every 1 horizontal foot). A slope of and/or primary dune systems. Bulldozing is Spacing should then be increased to 2 feet about 18.5 degrees (a rise of 1 foot for every expensive, potentially damaging to the and then 3 feet for several rows on each side 3 horizontal feet) is preferred. The initial coastal environment, results in short-term to allow sand to penetrate to the center of width of the dune base should be at least 20 benefits and needs to be perpetually the planting. feet. A dune with a smaller base will not continued. build to a height sufficient to provide storm Dune Protection protection (Texas GLO, 2001) Sand Fences and Vegetation Although dune plants tolerate harsh beach Barrier dunes are best located slightly The first step to dune establishment is conditions, they cannot withstand foot and landward of the location where foredunes providing a barrier to trap sand. Sand fences vehicular traffic. These activities crush plant would naturally occur to allow for natural create areas of lower wind speed both in shoots and roots, and trampling by seaward expansion and normal ocean tidal front of and behind the fence which pedestrians and traffic such as four- wheel- fluctuations. Dunes built too close to the encourages sand deposition. The amount of drive vehicles and trail bikes often lead to ocean can be destroyed by wave action sand trapped depends on the fence height, greater sand removal by wind. In addition, during even minor storms and may interfere the size of spaces between fence slats and the soil compaction often results from vehicular with public access along the beach. wind speed. Wooden slat fences are most traffic and decreases water infiltration, commonly used and are generally preferable leading to erosion from rain and increased As the dune accumulates sand it expands to fabric fences. damage during droughts. seaward, allowing plants to spread into freshly deposited sand. Some severely The initial dune crest is located by installing Restricting or banning access to dunes can eroding beaches do not have sufficient space a 2-foot-high sand fence several hundred feet reduce the need for other sand control to successfully use vegetation for dune behind and parallel to the high tide line to measures. However, some dunes will have to building. Where adequate distances exist accumulate wind-blown sand. The fence bear traffic, and to protect them, crosswalks between the ocean and property to be should be installed several months before and beach access areas should be designated. protected, well-vegetated dunes will provide transplanting vegetation to allow the sand to valuable protection from storm waves. accumulate without burying the transplants. Dune Crossovers Sand fences should be avoided in areas where Damage to dunes from pedestrian traffic can sea turtles are likely to nest. Imported sand should be similar in size and be avoided by the use of elevated walkovers mineral content to the sand at the dune- for access to the beach. If walkovers are Small areas and steep slopes should be building site. If native sand is topped with conveniently placed near access roads, planted by hand, while large, flat areas may imported finer sediment, the finer sediment parking areas, beachfront subdivisions, and be planted with tractor-drawn tobacco or will quickly erode. public facilities pedestrians will be less likely vegetable transplanters that have extended

42 to cut footpaths through the dunes. Also, sufficient elevation to accommodate the workers should enter the dune area on foot providing walkovers may increase public expected increase in dune height. rather than by vehicle. awareness of the importance of dunes and promote an appreciation of the sensitivity of The slats forming the deck of the walkover Enhancing Interior Dunes the dune environment. should be spaced 1/2 inch apart so that sunlight and rainfall can penetrate to plants Dunes found on island interiors serve an A walkover should begin landward of the below and so that sand will not accumulate important function with respect to property foredune and extend 10 to 15 feet seaward of on the deck. damage mitigation. Dunes provide elevation the vegetation line. The structure should be and protection from storm-surge flooding oriented at an angle to the prevailing wind Supporting piers should be placed as far and waves. Their height can also act as a direction. Otherwise, wind blowing directly apart as possible along the length of the shield against damaging wind. The removal up the path of the walkover may impede the structure (a distance of at least 6 feet of interior dunes eliminates the potential growth of vegetation beneath it, erode sand between pairs of piers is recommended). mitigation benefits they would have from the seaward end and increase the Piers should be implanted at least 3 feet in provided and allows storm impacts to possibility of washout or blowout the ground to ensure stability, although a become magnified. development (Texas GLO, 2001). depth of 5 feet or more is advisable to allow for erosion around the piers during storms. Unlike frontal dunes, once an interior sand Wood is the preferred construction material Damage to the dune area should be repaired dune is destroyed, it can only be rebuilt or for walkovers because it is less expensive than as soon as possible. repaired artificially by adding sand to the metal, does not collect and retain heat as system. This can be done independently, or metal does, and is readily adapted to a Providing handrails on both sides of the during a beach nourishment project when number of designs. Treated lumber and walkover is recommended as a safety sand-pumping equipment is readily galvanized nuts and bolts should be used. measure and to discourage people from available. A hypothetical interior sand dune jumping off into the dunes. Railings are 30 feet wide at its base, 10 feet wide at the The width of a walkover should be based on particularly advisable on public walkovers top, 10 feet high and 200 feet long would 3 the expected volume of pedestrian traffic. If and those that are high above the ground. have a volume of 1,500 yds . The estimated a walkover will be infrequently used, a width Railings should be at least 3 feet high. cost of constructing such a dune in South of 2 feet should be sufficient. Walkovers To enable handicapped people to use a Carolina is approximately $7,500.00 (Bush, intended for two-way passage should be walkover, inclined ramps with a 20-percent 1996). wider, perhaps 3 or 4 feet. A width of 6 feet slope (a 1-foot rise for every 5 feet in length) may be appropriate for a walkover subject to may be built at each end of the structure. Beaches heavy use. Ramps are recommended for any large public walkover. One of the primary roles of the open ocean The structure's height should be at least one beach is to absorb and dissipate storm to one and a half times its width to allow Walkovers should be inspected and energy. As a result, the beach serves as an sunlight to reach vegetation underneath. In promptly repaired. To avoid damage, effective natural buffer between an island's any case, the deck of the walkover must be of

43 interior and storm=related processes such as beach is simply doing what it has been doing The first documented beach nourishment surge and waves. for millions of years. project in the United States took place at Coney Island, NY in 1922-23. Between In addition to serving as a storm buffer, Along developed shorelines, situations like 1950 and 1996, the federal government beaches also provide habitat and act as this often lead to questions such as, "What, spent $1.64 billion on shore protection and sediment sources for the remainder of the if anything, should be done to the beach?" beach erosion control projects. Since 1996, island. In the absence of human impacts or As more and more human economic Congress has authorized over 40 beach influence, a natural beach will always remain development becomes vulnerable to coastal replacement projects that will cost more than in a state of equilibrium with its natural processes, the pressure to do "something" is $3.38 billion (TCS, 2001). surroundings. becoming greater every day. Although nourishment can be a viable In the same way that a beach reduces storm What, if anything, a community does to engineering alternative for shore protection impacts upon an island, the beach also acts manage its ocean beach for the benefit of and is the principle technique for beach as a buffer between storms and human human economic development depends restoration, there are a number of significant development. While a wide beach affords a upon a number of complex local, regional, issues surrounding the use of beach degree of protection for human state and federal factors. Whatever strategy is nourishment as a hazard mitigation development, it does not mean that all eventually chosen, one element in the alternative. In addition to being expensive, beaches should be artificially altered and decision-making process is absolutely nourishment is not suitable for all locations - maintained for human benefit. essential: all facts must be made public, especially those with high erosion rates. discussed and debated in an open forum. When the open ocean beach is artificially Beach nourishment projects are often managed or altered, two seemingly Some management alternatives that address undertaken without due consideration for incompatible elements must be considered - the conflict between static human economic the environment, without due consideration a naturally dynamic and highly development and the naturally dynamic for their impacts upon the littoral cell, unpredictable environment and static human ocean beach in North Carolina include: without due consideration for their impacts economic development. Conflicts only arise to the borrow site and without an effective when naturally-occurring coastal events and Beach Nourishment monitoring component. The adequacy of processes begin to impact upon human beach nourishment design methodology is economic development. Beach nourishment (or beach also a source of controversy. replenishment) is a beach stabilization For example, a major storm might remove technique used to restore an eroding beach In addition, most nourished beaches tend to sand from the sub aerial portion of the beach and create a new sandy shoreline. Beach erode faster than the natural beaches that including any frontal or primary dunes. nourishment involves the placement of sand preceded them because the “new” beach is From a human perspective, this is considered fill with or without supporting structures just piled on top of the upper beach, storm damage. From a geologic perspective, along the shoreline to widen the beach. Sand resulting in a beach that is steeper and out of however, this is considered normal - the sources include the continental shelf, inlets equilibrium with the local wave climate and associated tidal deltas, and (Bush, 1996). inland sand pits.

44 And, like hard shore protection structures, be scraped, leading to a net gain of sand on Maritime Forest beach nourishment has a finite life which the manicured beach. The goal of an On higher elevations where the substrates are depends on the intensity of the destructive enhanced recreational beach is achieved for unaffected by salt water flooding and heavy forces of nature and, occasionally, of human the short-term but the drawback is that no salt spray, maritime forest may occur. The activity (NRC, 1995). new sand is added to the system. forest is the climax of the successional process and is the stage that follows the If a community does decide to pursue beach Ideally, scraping is intended to encourage shrub thicket. The maritime forest is nourishment as a property damage onshore transport of sand, but most of the composed of tree species such as live oak, mitigation measure, it must understand that sand “trapped” on the lower beach is loblolly pine, red , red cedar and nourishment is a temporary (50-year) brought in by the longshore transport. American holly that are relatively resistant to solution that does nothing to address the Removal of this lower-beach sand deprives salt spray. underlying problem of a rising sea level and a downdrift beaches of their natural migrating shoreline. It must also realize that nourishment. The protective nature of maritime forest is nourishment is very expensive, highly clearly illustrated by the impacts of unpredictable and that it does not provide Beach scraping is widely applied in many Hurricanes Hugo in 1989 and Frederic in any environmental benefits. states, and although a beach’s width may 1979. In Hugo, overwash penetration and become slightly enhanced over the short- storm wave damage to property on Pawley’s Every community that pursues beach term, its effectiveness is relatively unproven. Island, SC was noticeably greater where nourishment should ensure that The general view on beach scraping is that it maritime forest had been removed for development densities do not increase should be treated as highly experimental, development. In contrast, many houses because of nourishment and should develop and that any community contemplating it located with the maritime forest were a long-term, post-nourishment mitigation should consider it as such. essentially untouched except for some plan that incorporates structural relocation. cosmetic damage. On Dauphin Island, AL Vegetation the unforested western segment of the island Beach Scraping suffered extensive damage while the forested eastern segment suffered less damage. This Beach scraping consists of moving sand from Preserving/ and Establishing pattern of damage on the island was repeated the low-tide beach to the upper back beach Native Vegetation in later storm events (Bush, 1996). (independent of building dunes). During Natural coastal vegetation, where it has not beach scraping, a thin (1 foot) layer of sand been disturbed, offers some of the best Every measure should be taken to protect is removed from over the entire lower beach defense against property damage during and preserve contiguous areas of shrub using a variety of heavy machinery and storms. For moderate-sized storms, dense thicket and maritime forest. Not only should spread over the upper beach. The objectives maritime forest, especially native species of as much forest as possible be retained, but are to build a wider, higher high-tide dry forest, provides significant protection to also, where appropriate, areas where trees beach; to fill in any trough-like lows that buildings. have been removed should be reforested with drain across the beach and to encourage native species. additional sand to accrete on the lower beach. Any newly accreted sand can, in turn,

45 One approach is to restrict the removal of The advantages of relocation are preservation accounted for over 60% of all coastal claims trees that have a trunk diameter less than a of the beach, preservation of buildings and under the amendment. defined standard, such as 2”. Another option reduced shoreline stabilization costs. The is to control development density so that as major drawbacks are that relocation can be The National Flood Insurance Reform Act much natural (or forested) land is preserved. politically difficult, costly and land will of 1994 terminated the relocation assistance ultimately be lost. program and replaced it with the National Innovative Development Policies Flood Mitigation Fund which would be When a building is threatened by erosion, financed by revenue collected for The mitigation alternatives discussed up to the costs and benefits of moving the noncompliance with National Flood this point involved direct or indirect structure back from the shore must be Insurance Program (NFIP) requirements. manipulation of coastal resources as a means weighed along with other alternatives such as The Fund provided state and local to alter the vulnerability of human coastal shoreline stabilization. Depending on the governments with grants for planning and development. The remainder of this chapter nature of the problem, a move-back can mitigation assistance for activities that will examines approaches that address compare favorably to other alternatives and reduce the risk of flood damage to structures vulnerability through the implementation of prove to be economically and aesthetically covered under the NFIP. innovative concepts and policies that directly superior in the long run. and indirectly involve the specific attributes Although demolition and relocation of human coastal development. Relocation has been employed on the coast activities were still eligible for funding, they for almost 150 years, and a 1987 had to compete with other mitigation amendment to the National Flood Insurance approaches such as acquisition, flood- Structural Relocation Program formally recognized relocation as a proofing programs and beach nourishment. The most obvious type of relocation is to more economical, permanent and realistic physically pick up a building and move it way of dealing with long-term erosion The 10/100-Year Relocation Concept somewhere else, either in one piece or in problems. Known as the Upton-Jones In some areas, such as Miami Beach and sections. Relocation can also mean Amendment, this statute allowed owners of Myrtle Beach, SC, beach nourishment may demolishing and rebuilding somewhere else. imminently threatened structures to use up be economically feasible because of the large Any active (before damage) or passive (after to 40 percent of the federally insured value number of people that use the beach and the damage) method of moving, or abandoning of the structure for relocation or demolition enormous amount of revenue generated. and rebuilding, is essentially what is meant purposes (Bush, 1996). There will come a time, however, when the by relocation. economics of nourishment are no longer The goal of the amendment was for the favorable, even in these highly-developed Abandonment may also be an economically federal government to pay a relatively small communities. sound option, especially when a building has amount of money to help move a structure, existed well beyond its design life and where rather than pay a much larger sum after the What do we do then? One possible answer the cost of moving, or protecting the structure has sustained damage. By March, is relocation or demolition. According to the building in place, exceeds the building’s 1995 North Carolina had claims for over 70 International Association of Structural value. relocations and 168 demolitions which Movers, even large structures such as high-

46 rise hotels and multi-unit condominiums impacts, and have failed to provide adequate Establishing setbacks that reflect site-specific can be safely moved. The only obstacles that environmental open space for coastal coastal processes, hazards and building styles must be overcome are cost and opposition processes. could be incorporated directly into a from beachfront property owners. community’s Land Use Plan along with An analysis of coastal erosion trends could certain construction and land-use One option available to all communities - provide data on a property scale to enhance performance standards for areas that fall large and small, developed and developing - decision making in the coastal zone area. within a particular erosion-hazard zone. Site- is to develop a 10/100-year relocation plan. Historical erosion rates can be determined specific setbacks would also offer a basis for This plan would contain a relocation strategy on a parcel by parcel scale and used to dune conservation. developed over a 10-year period and project the future erosion hazard area along implemented, as needed, over the next the shoreline. Maps projecting the 30-, 60-, Variable-rate setbacks may be difficult to century (Bush, 1996). Cost comparisons of and 90-year shoreline position, and that adopt, however, especially in communities traditional relocation or relocation by incorporate other hazard geoindicators, can where rapidly eroding shorelines could demolition could be considered and be developed. significantly limit the buildable area of many potential relocation sites identified. The goal beach-front parcels. is to plan now so that proper questions can These maps would provide a scientific basis be identified and addressed before they for more effectively locating proposed Staggered setbacks prevent entire rows of become problems. structures and activities in beachfront lots. structures from being lost in a single storm Coastal hazard maps could also be used to (as was the case in Oak Island, NC during Staggered Shoreline Setbacks establish hazard-based building setbacks. Hurricane Floyd), thereby minimizing the Setbacks would be site-specific, at the severe financial impacts that even a moderate Setbacks allow the natural erosion and property scale, to reflect the site-specific hurricane may have on a community accretion cycles to occur and help maintain nature of coastal hazards. These setbacks lateral beach access. Setbacks also provide would also incorporate the proposed style of Orientation and Placement of Roads open space for the enjoyment of the natural development. and Infrastructure shoreline environment. The intent of staggered shoreline setbacks is to establish a Construction-style considerations would Most structural mitigation measures variable buffer zone that protects beach-front include the size and expected lifetime of the concerning development deal with development from high-wave events and planned structure. Larger, immovable engineering and/or building codes. Other coastal erosion buildings and those with lifetimes of more measures, such as those that mitigate damage than 60 years, for example, would have to utilities and other infrastructure, have to It is the opinion of PSDS that existing NC deeper setbacks than small, movable do primarily with orientation, placement, shoreline setbacks are inadequate because structures. For instance, a ten-story, 200- layout and design. they do not consider acute storm impacts unit condominium would have a deeper and other geologic hazards. Along much of setback than a single-family house built on Based on the damage patterns observed after the North Carolina coastline, setbacks have posts. Hurricanes Gilbert and Hugo, it has become failed to protect developed beach-front clear that road orientation, design and property from coastal erosion and storm

47 placement can influence storm processes and In those areas where infrastructure is located, and would cost approximately $10,000 is a major factor contributing to property the following mitigation strategies may be apiece. damage. During Hugo, for example, water, used. sand and debris were carried inland along Road Elevation shore-perpendicular roads in several Road Realignment Many coastal communities have roads at communities. On one South Carolina island, If the direct line created by straight roads dangerously low elevations, making them boat ramps served as conduits for the return perpendicular to the shore can be vulnerable to overwash, undermining and of storm water (storm-surge ebb) back across interrupted, the amount of damage done by flooding. While some communities would the island from the , causing scour overwash and storm-surge flood and ebb be better off prohibiting any new channels that undermined roads and waters may be reduced. construction along these roads, other damaged homes. communities can benefit by elevating The first hazards that should be addressed sections of roads, thereby allowing natural Some of the problems associated with are dune gaps located at the ends of shore- processes to continue with minimal impacts. standard road layout designs and practices, perpendicular roads. These gaps should be however, can be remedied, or at least plugged, or at least partially filled to slow Road elevation design must pay careful alleviated, through the implementation of down storm-surge ebb velocity enough to attention to natural processes so as not to innovative mitigation alternatives. It should reduce the scouring potential of the flow and interfere with natural drainage or sediment be noted that because development is reduce or delay the intrusion of storm waves transport. When roads are located or dependent upon infrastructure, and because into the community. rebuilt/relocated after storms, for example, infrastructure encourages additional they should be elevated above the initial development, all coastal communities should Adding a few simple curves, instead of flood level of a storm in order to allow for implement the following two-part strategy: having all access roads run perpendicular to evacuation. This additional elevation may 1) permanently move infrastructure in the the shore, would greatly reduce the impact also offer protection against storm-surge most vulnerable locations, and 2) prohibit of overwash and storm surge ebb. Existing currents. future infrastructure from being located in roads could either be removed and rebuilt, or these locations. curved to interrupt the existing grid pattern, There are two possible approaches for in order to eliminate the conduit effect. New elevating a road. The first is to construct a Not only would this reduce the amount of roads could simply be laid out in a non- bridge, causeway or other structure that development in high-hazard areas, it would linear, non-perpendicular manner. physically raises and maintains the road at a also support the goals of the Coastal Barrier constant height above the ground surface. A Resources Act of 1982. The CBRA Another option is the placement of sediment second alternative is to construct eliminated federal development incentives mounds - artificially-created, T-shaped sand “temporary” roads that are “sacrificed” on undeveloped coastal barriers with the dunes - at specific street intersections and at during storms and that can be quickly intent of preventing the loss of human life the end of finger canals. Sediment mounds rebuilt, post-storm, on top of any sediment and property from storms, minimizing can be designed to function as parks (albeit that gets deposited. This option allows an federal expenditures and protecting habitat small ones) or used for aesthetic plantings, island’s elevation to build-up naturally, and for fish and wildlife.

48 may prove to be both inexpensive and measures include land-use planning and areas may be revised. This could include the environmentally-sound. zoning ordinances that require an intimate application of current CAMA Inlet Hazard understanding of coastal processes in order Areas Use Standards to the newly delineated Inlet Hazard Area Restrictions to delineate the most hazardous areas and areas, or the development of more restrictive avoid potential hazards. use standards. Land near inlets is subject to inlet migration, rapid and severe changes in watercourses, Defining Inlet Hazard Areas Enforce Building Codes flooding and strong tides. Because of their Inlet Hazard Areas currently fail to account dynamic nature, North Carolina has Good code enforcement can make a for the significant, and often rapid, shoreline designated land adjacent to inlets as hazard significant difference in the losses incurred changes that can be caused by major storm areas and areas of environmental concern. by a storm event, especially related to mobile events. In addition, Inlet Hazard Areas also homes. There is a strong correlation between do not include land that may be influenced The NC Inlet Hazard Area extends landward good code enforcement, new construction some distance away from the inlet. from the mean low water line a distance that complies with NFIP regulations for sufficient to encompass that area within elevation and construction and reduced To address these issues, a community should which the inlet will, based on statistical flood and wind damages. Structures built consider expanding the boundaries of the analysis, migrate, and shall consider such before NFIP regulations were strictly Inlet Hazard Area within its jurisdictional factors as previous inlet territory, structurally enforced in South Carolina in the early boundaries in order to encompass all areas weak areas near the inlet and external 1990s suffered severe flood damages during that are, or may be, impacted or influenced influences such as jetties and channelization Hurricane Hugo. by inlet processes. This task can be (CAMA, 1974). accomplished by evaluating post-storm The North Carolina State Building Code is shoreline changes and by examining aerial Although our understanding of the an adaptation of the Standard Building photographs. complexity of inlets, their dynamics and Code that incorporates significant changes their importance to barrier island processes made by the North Carolina Building Code Inlet Hazard Areas also only pertain to has grown significantly since the North Council. Since the 1960s, North Carolina modern inlets and do not consider relict or Carolina Coastal Resources Commission has had a special building code for one- and historical inlet locations. A community designated the current inlet hazard areas in two-family dwellings, called the Residential should determine whether any historic or 1978, use standards and boundary line Building Code, which is based on the relict inlets are present and designate those determinations have remained static Council of American Building Officials areas as hazardous areas as well. These (CAMA, 1974). Code with amendments from the North geologic features can be identified through a Carolina Building Code Council. literature search as well as through an We now know that inlets are not fixed evaluation of aerial photos. features, that each inlet is unique and that Since the 1960s, most houses on the North they all require a special consideration in Carolina coast have been built on pilings. applying principles of property damage Use Standards in Inlet Hazard Areas Before 1986, codes required pilings to be mitigation because a special set of natural In addition to establishing new inlet hazard embedded 8 feet below grade. In 1986, the processes are at work. Inlet hazard mitigation area boundaries, use standards within these code was revised so that buildings closer than

49 60 times the long-term erosion rate to the Tie-downs should be, and often are, required 2. A building with a planned long life, such as a year- seaward edge of the first line of stable to make a mobile home more stable against round residence, should be stronger than a vegetation must have pilings embedded 5 wind stress. Violations of anchorage or building with a planned short life such as a mobile feet below mean sea level or 16 feet below foundation regulations may go undetected home grade, whichever is less. unless there are a sufficient number of 3. A building with high occupancy, such as an conscientious inspectors to monitor trailer apartment, should be safer than a building with a Since 1997, a strengthened Residential Code courts. One poorly anchored mobile home low occupancy, such as a single-family dwelling applies to new houses built up to 100 miles can wreak havoc on adjacent homes whose 4. A building that houses elderly or sick people should inland from the coast. The private sector owners abide by sound construction be safer than a building housing able-bodied should work closely with state and local practices. people governments to develop incentives, 5. Construction costs that incorporate a higher than usual margin of safety will be higher than costs for disincentives and revised insurer practices to Replace Pavement with prevent or mitigate wind, flood and related an average home Porous Surfaces damages through improved building 6. The risk of loss may make a project unfeasible practices (Pilkey, 1996). A simple method that may help reduce Builders commonly assume that the scouring is to remove pavement and replace foundation and framing of a structure must it with rounded , gravel, sand or Mobile Home Regulations support the load of the walls, floor and roof, some other porous surface. This adds some Mobile homes differ in both construction and relatively insignificant horizontal wind roughness to the surface and allows water to and anchorage from “permanent” structures. forces. A well-built house in a hurricane- seep into the ground, rather than flow The design, shape, lightweight construction prone area, however, must be constructed to directly back to the ocean or sound. materials and other characteristics required withstand a variety of strong wind and wave for mobility also creates a unique set of forces that may come from any direction. potential problems for residents of these Structural Design Considerations dwellings. Because of their thinner walls, for Designing for Wind example, mobile homes are more vulnerable A certain chance of failure exists for any to wind and windborne projectiles. structure built within the constraints of According to the building code, the design economy and environment. The objective of wind speed for North Carolina is 110 mph, Recognizing the effects of coastal zone building design is, therefore, to create a the fastest mile for a 50-year return processes on these structures, North Carolina structure that is both economically feasible frequency. Most wind damage is not caused has a separate building code for mobile and functionally reliable. by uniform horizontal pressure. Rather, it is homes. The code requires that mobile homes caused by uplift (vertical), suctional manufactured after October 1, 1973 meet There are six fundamental considerations (pressure-differential) and torsional the state’s hurricane-zone requirements. that should be incorporated in the design (twisting) forces. High horizontal pressure of Mobile home anchorage is commonly and construction of a coastal structure: the windward side of a structure, for regulated by local ordinances, and most NC example, is accompanied by suction on the counties and municipalities have ordinances 1. A coastal structure exposed to high winds, waves leeward side. In addition, the roof is subject pertaining to mobile homes. and flooding should be stronger than a similar to downward pressure and, more important, structure built inland

50 to uplift. Houses that fail usually fail because Structural integrity is also important if it is design. For instance, the pressure on a the devices that tie their parts together fail. likely that the building may eventually be curved surface, such as a cylinder, is less than moved. the pressure on a flat surface. In addition, All structural members should be fastened wind velocities increase with height above together on the assumption that about 25 The amount of force the wind exerts on a the ground, so a tall structure is subject to percent of the vertical load on each member building can be modified by several factors, greater pressure than a low structure. may be a force coming from any direction. which must be considered in building

51 52 COMMUNITY CASE STUDY 1: ATLANTIC BEACH, NC

Community Overview The town was officially chartered in 1937 become the leading type of dwelling unit (Atlantic Beach Land Use Plan, 1996). constructed (Atlantic Beach, 1996). Atlantic Beach is located on the eastern end The 1995 construction value for all of Bogue Banks, an east-west trending island Over the last 30 years, Atlantic Beach has residential dwelling units was $2,644,721. in the North Carolina barrier island system evolved from a predominantly vacant Figure AB1). The amount of land area in landscape to a predominantly developed Today, Atlantic Beach is a mixture of Atlantic Beach is 5.95 km2 and the amount community. Rapid and uncontrolled commercial and residential uses that are of surface water is 0.471 km2. development in Atlantic Beach has resulted primarily seasonal and oriented. The in narrowed dunes, filled marshlands, finger majority of commercial development is Bogue Banks extends from 34o 38’30’’N, 77 o canals and removal of most native vegetation located along NC 58, on both sides of the 06’00’’E to 34 o 41’30’’N, 76 o 40’30’’E. The (Pilkey, 1998). During this time, significant Causeway and in an area known as the 40 kilometer-long arcuate island is situated areas of were bulkheaded and “circle.” Most of the town’s commercial between two tidal inlets: Bogue Inlet on the filled, and a significant amount of development is old and is showing signs of west and Beaufort Inlet on the east. development took place on small lots deterioration (Atlantic Beach, 1996). Landward of the island is Bogue Sound, a unsuitable for septic systems. As of 1996, approximately 72 acres of vacant shallow lagoonal system that ranges in width During the 1980s, construction in Atlantic land remained for development. The town from .4 to 2.4 kilometers. The predominant Beach was dominated by multi-family units. has projected that its remaining vacant land littoral current at Atlantic beach is from west Since that time, single-family units have could accommodate an additional 750 to east (Stanczuk, 1975).

Development During the 1930s the tract of land surrounding the “circle” was platted with lots and streets extending out to the east and west. Streets running east and west were called Boulevards and named for local geographical features. Those running north and south were called Avenues and named in honor of towns and cities in North Carolina. Lots were sold, and in 1932 the first cottage was built (Town of Atlantic Beach, 2001). FIGURE AB 1: Aerial View of AtlanAtlantictic Beach, NC

53 dwelling units, and that build-out would Atlantic Beach is connected to Morehead frequency. When the scour becomes great occur sometime during 2010 and 2013 City, on the mainland, by a fixed, high-span enough, the structure can be undermined. (Atlantic Beach, 1996). bridge that was constructed in 1970 (Stanczuk, 1975). Tidal currents flowing through Beaufort Projected Development Trends Inlet rapidly eroded the high water line in During the next 20 years, public land use Several areas of the town experience Atlantic Beach between 1939 and 1953. The changes in Atlantic Beach may include congestion (especially during peak season) sound side of Atlantic Beach had an erosion redevelopment of the “circle” and and poor emergency vehicle access. These rate of approximately 1 foot/year during this construction of a central sewer treatment areas include the Causeway, the Circle, NC period. and collection system. These changes will 58 and the Money Island subdivision where likely increase property values, promote the streets are improperly aligned. Atlantic Beach experienced eight hurricanes conversion of existing mobile home parks to between 1953 and 1958, including permanent residential dwelling units, Shoreline Changes Hurricane Hazel in October, 1954. Hazel increase traffic congestion and allow for the caused significant beach and dune erosion Dune stabilization projects on Bogue Banks dispersion of commercial development. and extensive property damage. Although began in the late 1930s. Although the intent still rapid, erosion at Fort Macon slowed to of dune stabilization is to protect half of what it was from 1939 to 1953. Population development from storm wave damage, During the period 1980-1994, the stabilized dunes also act as dikes, preventing In the early 1960s, a jetty was built at Fort permanent population of Atlantic Beach storm overwash from reaching the interior or Macon, and by 1971, most of Bogue Banks increased 241%, from 941 to 2,267 persons back-side of the island. This, in turn, was experiencing an accreting shoreline. This (Atlantic Beach Land Use Plan, 1996). In eliminates new sand from being deposited apparent reversal of erosion may have 1999, the population of Atlantic Beach was across the island, resulting in a general resulted from fewer major storms along with 2,320 and is expected to reach 3,050 by increase in erosion. increased dune stabilization. Erosion along 2003 (OSBPM, 2001). The town’s peak the sound-side of Bogue Banks, however, seasonal population is approximately 11 The first bulkhead in Atlantic Beach was continued during this time. times the permanent population (Atlantic built in 1956 (bulkheads are vertical Beach Land Use Plan, 1996). structures, located at the dune line, that are Geology/Morphology built to prevent dune erosion and protect development from wave action). While Carteret County is underlain by an eastward- Transportation bulkheads often do prevent dune erosion, thickening wedge of age There are approximately 23 miles of roads in they also discourage dune accretion. sediment deposits ranging from 2,000 feet Atlantic Beach. Sixteen miles are town Bulkheads tend to reflect wave energy which thick in the northwest portions of the county owned and maintained, 6 miles are state can lead to scour at the toe of the bulkhead. to almost 7,000 feet thick beneath the owned and maintained and .88 miles are As this scoured material is removed, the easternmost sections of offshore beach privately owned and maintained (Atlantic slope of the beach decreases and the lower (Figure AB2). Shell fragments and calcareous Beach Plan, 1996). beach face may eventually become material are consolidated into a limestone at completely inundated with increasing a depth of less than 120 feet west of

54 Hazard Geoindicators

As previously discussed, hazard geoindicators are local geomorphologic features that can, and do, influence coastal processes. The primary hazard geoindicators found in Atlantic Beach include:

Topographic Geoindicators

Elevation The average elevation of Atlantic Beach is eight feet above sea level. The highest natural elevation is approximately 20 feet in a residential area immediately east of the FIGURE AB 2: GeoloGeologygy of Circle (circled area in Figure AB4). At the North Carolina’s Coastal Plain Circle itself, the central dune ridge was completely removed for development.

Because of its low elevation, approximately half of Atlantic Beach is located within either a V-or A- NFIP Flood Zone (Figure AB3). Morehead City, and at increasing depths proximity of Cape Lookout, however, This means that a significant amount of the further eastward. indicate that Atlantic Beach is somewhat sheltered from community is at or below the 100-year base the uppermost consolidated limestone is large storm waves that predominate from an flood elevation. A paved notch in the dune probably part of the Yorktown Formation east-northeasterly direction (Stanczuk, ridge immediately seaward of the Circle has (Atlantic Beach Plan, 1996). 1975). The hazardous processes of interest in exposed downtown Atlantic Beach to storm Atlantic Beach are storm surge and storm surge and makes the main evacuation route Hazardous Events/Processes overwash. extremely vulnerable to storm surge flooding. Except for the dunes, slopes Atlantic Beach is subject to hurricanes, throughout the town are generally between tropical storms and extratropical cyclones. zero and eight percent (Atlantic Beach Plan, Due to its east-west orientation and the 1996).

55 Vegetation Vegetation native to Atlantic Beach includes Spartina patens (cord grass), Ammophila breviligulata (American beach grass), Uniola paniculata (sea oats), Baccharis halimifolia (eea myrtle), Myrica cerifera (wax myrtle), Iva frutescens (marsh elder), Quercus virginiana (live oak), Juniperus virginiana (red cedar), Slex vomitoria (yaupon) and Spartina alterniflora (smooth cord grass). All vegetation was removed from the area around the Circle to make room for development. Most of the remaining areas of intact maritime forest in Atlantic Beach are located on scattered parcels north and south of NC 58 between Cedar Lane and the general area of the Ocean Ridge/NC 58 intersection.

Shoreline Geoindicators Shoreline geoindicators include geomorphologic features of the ocean beach, the estuarine shoreline and the offshore continental shelf. This category of FIGURE AB 4: LIDAR Elevation Data for the “Circle” Area of Atlantic Beach geoindicators influences storm surge height, storm wave height, wave energy and storm surge ebb flow.

The Ocean Beach The average, long-term erosion rate in Atlantic Beach is approximately 2 feet/year (Pilkey, 1998). The ocean beach in Atlantic Beach is, however, artificially maintained and two nourishment projects have placed approximately 6 million yds3 of sand on the beach during the past 15 years. FIGUREFIGURE AB 3:3: FlFloodood ZZonesones fforor AtlanticAtlantic BeachBeach, NC

56 In 1986, approximately 2.5 million yds3 of sand that was dredged from Beaufort Inlet was placed on the beach from near the Triple S Pier west to just beyond the Atlantic Atlantic Beach Beach municipal boundary (Bush, 1996). The beach was widened and sand fencing has resulted in modest dune growth. Another 3.5 million yds3 of dredged sand was placed on the beach in the same general vicinity in 1994 (BBBAP, 2001).

The beach currently ranges in width from 10 to 120 meters from the dune line to the high water line.

Primary/Frontal Dunes Atlantic Beach is fronted by a discontinuous, staggered dune line that ranges in height from 0 to over 20 feet. Because the sediment that was dredged from the inlet and deposited on the beach had a high mud content, dune and beach erosion scarps are common, especially east of the circle.

Bathymetry The bathymetry of eastern Bogue Banks is illustrated in Figure AB5 to the right. Atlantic Beach is located at the northern edge of , a microtidal environment with a mean tidal range of FIGURE AB 5: Bogue Banks Bathymetry about 1 meter (Figure AB 6 on the next page). Hindcast wave data (WIS studies) indicates a mean wave height of 1.1 meters, with a 7 second period.

The Onslow Bay shelf is sediment-starved and the introduction of new sediment to

57 to transgressive (sediment-starved). The transgressive shoreface segment off FIGURE AABB 6 Shackleford is similar to the shoreface off other transgressive barriers in Onslow Bay such as Wrightsville Beach and Topsail Island.

Three possible explanations for the features observed on the eastern Shackleford Banks shoreface have been proposed:

1. they are rippled scour depressions that result from bottom scour by strong, channelized offshore- directed flows (if true, then the rippled areas indicate the presence of sediment transport conduits between the beach and the shelf);

2. the linear rippled areas are sediment-starved, flow- transverse bedforms formed and maintained by longshore currents. The proximity to Barden's Inlet suggests longshore or tidal currents may be locally important. Onslow Bay is negligible due to: 1) no collected in May 1997 indicates that the fluvial input (coarse sediments are trapped in shoreface seaward of these regressive barrier 3. the coarse sediments are lag deposits from relict the upper estuarine system) and 2) minimal islands is fundamentally different from the estuarine tidal channels and thus indicate that the sediment exchange between adjacent shelf transgressive barriers that line much of shoreface is actively eroding. embayments. Onslow Bay shelf sediment Onslow Bay. cover has been classified as residual (meaning Storm Surge it has been derived from the erosion of On Bogue and western Shackleford Banks, Estimated hurricane storm surge elevations underlying sediments and rocks (USGS, the entire shoreface is composed of uniform for Atlantic Beach are illustrated in Figure 1998). fine sand. The shoreface off eastern AB 7 on the next page. Surge elevations are Shackleford Banks, however, is covered with for a fast-moving hurricane and are derived Analysis of geophysical data from the coarse-grained, rippled sediments interpreted from the SLOSH model. shoreface and inner shelf of northern to be products of reworking in a sediment- Onslow Bay (Bogue and Shackleford Banks) starved shoreface environment. This change The Estuarine/Backside Shoreline suggests a direct coupling between shoreface in shoreface morphology corresponds geologic framework and subaerial barrier directly to a change in barrier island The soundside shoreline of Atlantic Beach is island morphology. Sidescan-sonar imagery morphology from regressive (sediment-rich) largely characterized by an eroding salt marsh, canals that were dredged to provide

58 access to Bogue Sound and artificial fill used dredging in 1910, 1936 and 1960 deepened Non-Shoreface Geoindicators for development. the channel from its original depth of 15 feet to a depth of 35 feet. There are eleven different soil associations Inlet Geoindicators found within Atlantic Beach, most of which In 1961 the outer channel of Beaufort Inlet have some type of development limitations. Atlantic Beach has two inlet hazards: 1) was deepened to 35 feet from its natural Beaufort Inlet and 2) a relict inlet that depth of 15 to 18 feet. Twice since, the Mitigation Recommendations persisted from the mid 1700s until about channel has been further deepened and 1800 (Bush, 1996). The central portion of lengthened and is now maintained at a depth Atlantic Beach contains areas that range Atlantic Beach including Morehead Avenue, of 45 feet. from extreme risk to low risk. Figure AB 8 the main road leading to the causeway and provides a detailed illustration of risk and mainland, is built on the natural fill of this Each year the US Army Corps of Engineers hazard geoindicators in Atlantic Beach. inlet’s tidal delta. removes 700,000 to 1,000,000 cubic yards Figures AB9 and AB10 provide a more of sand from the inlet which is deposited at generalized overview of risk. Massive dune ridges distinguish the island an off shore site. The total amount of sand from the low elevation historical inlet area. in the inlet's ebb tidal delta is estimated to Areas of extreme risk are indicated in Figures Navigation dredging of Beaufort Inlet began be 33 million cubic yards (USACE, 2001). AB8 and AB9 and include the immediate in 1850 with the opening of the port open ocean shoreline, land immediately west terminal at Morehead City. Subsequent of Fort Macon State Park, the Circle, the Causeway and the area known as the “Finger Canals.”

Because of the ongoing beach nourishment project, shoreline migration is not considered a priority hazard at this time. Even though the beach is artificially maintained, oceanfront properties and low areas are still subject to storm surge, flooding and storm overwash.

While erosion problems associated with a migrating shoreline in Atlantic Beach are not addressed in this section, it does not mean that erosion will not become an issue once nourishment ceases, nor does it mean that FIGURFIGUREE AB 7 7:: Hurricane Storm Sur Surgege EElevationslevations for a Fast Movin Movingg Hurricane (source:(source: NC erosion should not be considered during the development process.

59 A priority hazard mitigation recommendation for Atlantic Beach is to establish more stringent community-wide building restrictions in the event a central FIGURE AB 8: sanitary sewer system is constructed. Coastal Hazards Studies have shown that central sewer in AtlAtlanticantic Beach systems result in an increase in building density and size. With established development restrictions already in place, the town can significantly reduce the amount of future development that becomes vulnerable to coastal storm processes.

Open Ocean Shoreline Even though the open ocean beach in Atlantic Beach is artificially maintained, development immediately adjacent to the shoreline remains at extreme risk from a major hurricane as well as from extra tropical cyclonic activity. General Implementing Actions: • Construct and maintain a continuous frontal/primary dune field along the entire oceanfront of Atlantic Beach. • Increase the volume of the frontal/primary dune field using compatible sand from a source other than the beach. • Establish dune vegetation using native species. • Plug all dune gaps and prevent the creation of new gaps. • Construct dune crossovers, both pedestrians and vehicular, where access to the beach is desired.

60 • Allow sand, deposited by storm surge and storm • Relocate/remove structures and maintain as • Construct sediment mounds at the landward overwash, to remain in place. passive open space ends of shore-perpendicular canals and at other potential points of breaching. • Establish a "dune migration zone" and establish • Allow overwash sediment to remain in place staggered setbacks distances based on this • Plant and encourage the growth of native Post-Storm Redevelopment Issues zone so substantially damaged structures are vegetation rebuilt in a nonlinear fashion. A major storm could have profound impacts • The Circle upon Atlantic Beach, and a Category 3 or Increase building density and building size greater hurricane would result in substantial restrictions on all oceanfront lots. • Construct a substantial frontal/primary dune and damage town-wide. Current town policy • Establish a program to fund the purchase of lots plant native vegetation allows for the reconstruction of any structure containing "imminently threatened" structures • Increase interior sand volumes by adding demolished by natural disaster or by other and lots with substantially damaged structures - sediment from an off-island source causes in accordance with all applicable all publicly-owned lots should remain as federal, state and local regulations (Atlantic permanent open space. • Relocate/remove structures and maintain as Beach, 1996). passive/active open space • Investigate the possibility of developing a long- term retreat/relocation/evacuation plan for all • Allow overwash sediment to remain in place According to the town’s 1996 CAMA Land oceanfront structures in the event that beach Use Plan, it is town policy to “promote, • Plant and encourage the growth of native nourishment is discontinued foster and encourage the redevelopment of vegetation old, poorly-designed and underutilized Area Immediately West of areas” and that “redevelopment of these areas The Causeway Fort Macon State Park is preferred and deemed more important • Elevate the existing roadbed than development of currently undeveloped This area of Atlantic Beach is extremely low • areas.” and has experienced numerous storm Consider building an elevated causeway overwash episodes. It is also possible that an "Finger Canals" Actual development and redevelopment inlet was once located in this area. potential will be greatly influenced by • Fill-in existing finger canals General Implementing Actions: construction of a central sewer system • Shorten existing canals by infilling the heads of (Atlantic Beach Plan, 1996). • Increase interior sand volumes by adding each canal sediment from an off-island source

61 FIGURE AB 9: Risk Assessment for western Atlantic Beach, NC

62 FIGURE AB 10: Risk Assessment for eastern Atlantic Beach, NC

63 64 COMMUNITY CASE STUDY 2: NAGS HEAD, NC

Community Overview dwelling units, of which 62 percent are Residential single-family and duplex units. As of 1997, the Town had 5,080 dwelling Nags Head is located on North Carolina's units, 3,129 of which were single-family Outer Banks on a narrow spit situated Nags Head can be divided into two sections: units. Over the last twenty-one years, on between the Atlantic Ocean to the east and North of Whalebone Junction and south of average, 83 percent of new dwelling units to the west. Within the Whalebone Junction. Whalebone Junction is built have been single-family or duplex. Town is approximately 11.29 miles of the area in which State Highway 64 However, over the last ten years, 97 percent oceanfront shoreline that stretches south intersects with State Highways 12 and 158. of the dwelling units constructed have been from Eighth Street to the southern municipal boundary adjacent to the Cape The area south of Hatteras National Seashore. Whalebone Junction is FIGURE NH 1 relatively wide but low in elevation with the foredune Development having the highest From its early beginnings in the 1800s, Nags elevation. Development in Head has consisted predominantly of single- this area is limited to Old family cottages and a few hotels. Like all of Road and the Dare County beach communities, Nags consists primarily of single Head, especially during the mid- to late- family dwellings. A large 1980s, experienced tremendous growth and hotel and several multi- development pressures. The most significant unit condominiums are growth pressures in the Town are, and will situated just south of the continue to be, generated by seasonal resort intersection of Highways development 12 and 64. In the area north of The amount of land area in Nags Head is Whalebone Junction, approximately 4,300 acres. As of 1997, development extends from 2,805 acres had been developed and 976 the oceanfront across the acres were unplatted, undeveloped, privately island to the sound. This owned and subject to development. An area also contains all of additional 500 acres were in rights-of-ways Nags Head's commercial (ROW) and not available for development development. (Nags Head, 2000). The Town has 5,080

65 single-family and duplex units. At build-out, oceanfront is Nags Head Inn which was Zoning Districts which is projected to be in 14 to 18 years the constructed in the mid-1980s. Town will have approximately 6,914 The Town of Nags Head has ten zoning dwelling units, an increase of 1,834 from Little undeveloped land is available to build districts and several areas of extraterritorial what the town has now (Nags Head, 2000). new hotels and motels along the oceanfront. jurisdiction. Some of the districts such as R- In all likelihood, any new construction of 1, R-2 and R-3, are set aside primarily for Due to development on lots that were hotels and motels on the oceanfront will residential development. Districts such as platted before the incorporation of the Town involve redevelopment with the the C-2 District allow a mixture of in 1961, the density of lots developed prior recombination of existing lots into large commercial and residential uses, while to 1980 is higher than the density permitted parcels that can accommodate these uses. other districts, such as the C-3 (Commercial by the current Zoning Ordinance. Both uses are allowed by the Town’s Zoning Services District), are very limited in what Ordinance. commercial uses will be allowed. The typical minimum residential lot size has gradually increased from 7,500 square feet in Commercial and Non-Residential R-1: Low Density Residential District 1962, to either 15,000 or 20,000 square Between 1974 and 1990 five major shopping The R-1 District was intended to encourage feet today. The average lot size for single- centers were built (Surfside Plaza, 24,600 the development of low-density residential family development between 1985 and 1996 square feet; Nags Head Station, 18,000 neighborhoods. There are two R-1 was 12,000 square feet. As more of the older, square feet; Satterfield Landing, 44,700 residential districts in Nags Head. One is smaller lots of record are used up, the square feet; Outer Banks Mall, 138,600 located along the oceanfront between average lot size will increase and so, too, will square feet; and Soundings Factory Outlets, Jockey’s Ridge State Park and Diamond the size of the structures on those lots. In 84,000 square feet). From 1990 to 1997, six Street adjacent to South Virginia Dare Trail. 1986, for example, the average size of a new projects in excess of 10,000 square feet were 2 The other R-1 District area is off the Nags single family structure was 1,398.45 ft . In built. 2 Head-Manteo Causeway and includes Pond 1996, it was 2,442.41 ft (Nags Head, Island, and portions of Cedar and Horse 2000). Nearly all of the commercial development in Islands. Nags Head is located along South Croatan Hotels and Motels Highway (US 158) and most of the multi- There are approximately 58 acres of There are 766 hotel and motel units along family and motel development is located on undeveloped land in R-1. A large portion of the Nags Head oceanfront. Many of the or near the oceanfront (Nags Head, 2000). this undeveloped land (54 acres) is located structures housing these units are one story on Cedar and Horse Islands, and the land high, with a few three stories high. Notable Of the structures that exist east of NC 12 areas on the south side of the Causeway near exceptions are the Comfort Inn (built in and NC 1243, 51% were built before 1972 Pond Island. The tracts along the Causeway 1974) which is seven stories and when building codes did not specifically appear to contain a significant amount of approximately 65 feet high and the Nags address enhanced coastal construction wetlands. Excluding these parcels, there are Head Inn which is four stories and fifty feet methods and materials. ten lots available for development. With the in height. The last hotel to be built on the exclusion of these parcels, 95.8 percent of the land area in R-1 is developed.

66 R-2 Zoning District The first two areas are in the northern part district which consists of four areas along the of town between Wrightsville and Memorial oceanfront. The R-2 District was intended to encourage the development of moderate-density Avenue. One area is from Eighth Street to an area just past Atlas Street, and the other R-3 The C-2 District is 465 acres in size, residential neighborhoods with a mix of provides for the grouping and development permanent and seasonal residents, and also area is between Gallery Row and Abalone Street, The largest R-3 area is comprised of of commercial facilities and is distributed in to serve as a transition zone between the low- several areas throughout the town. The density areas and more intensely developed parts of Vista Colony, Vista Colony South, and most of the area south of Dowdy’s largest section of C-2 is between US 158 and areas. There are three R-2 residential areas. Virginia Dare Trail from Jockey’s Ridge Amusement Park between the highways. This includes the Enclaves subdivision, the State Park south to South Nags Head. Other The northern area is on the west side of C-2 areas include both sides of US 158 from Croatan Highway and includes Carolinian area around Linda Lane, part of Nags Head Shores subdivision, and the Stronach Tract Eighth Street to Villas Dunes Drive on the Colony, Oak Knoll Estates, Nags Head west and from Eighth Street to Dowdy’s Acres, Vista Colony West and the Hills at which is located between US 158, Fresh Pond Avenue, and Hollowell Street. The Amusement Park on the east; between Nags Head subdivisions. A second area is Memorial Avenue, Fresh Pond Drive and west of US 158, between Soundside Road fourth area includes the Town Hall Complex, Hawk’s Nest subdivision just to Virginia Dare Trail and on the west side of and the Outer Banks Mall and includes US 158 from the southern boundary of The South Ridge and Old Nags Head the south, and an undivided parcel to the south of the Hawk’s Nest subdivision. Village at Nags Head south to the Nags subdivisions. The third area is generally Head–Manteo Causeway. south of Whalebone Junction and includes There are 116 acres in R-3 of which 59 are developed. Of the developed land, 95 most of South Nags Head including the The C-3 Commercial Services District is oceanfront. Permitted uses in R-2 include percent has been developed primarily as single-family residences. located west of the Satterfield Landing single-family and duplex houses, and Shopping Center between Eighth Street to municipally owned public access facilities. Commercial Zoning Districts the north and Carolinian Colony subdivision to the south. The district is 29.7 There are 881 acres in R-2 of which 61 The town has five commercial zoning acres in area, is 89.5 percent developed and percent is developed. Of the developed land, districts: CR, C-2, C-3, Village Commercial is the only district in Nags Head that does 92 percent of the land area is devoted to and C-4. not permit single-family houses. single-family and duplex residential uses. The CR District is an area in which the The Village Commercial District permits the R-3: High Density Residential District principal use of the land is for intensive development of residential areas of low-to The R-3 residential district was established recreational purposes and for those types of moderate-density with a mixture of as an area for high-density residential developments which, by their nature, are professional commercial activities of limited development. This district also provides for best located in close proximity to the Town’s size. development of less intensive residential uses ocean beaches. The district also provides for as well as compatible supporting uses. There less intensive recreational uses as well as There is one C-4 District located in an area are four R-3 areas within the town. compatible supporting uses. As of January 1, just south of Atlas Street extending to an 1997, 34 lots remained undeveloped in this area just south of Gallery Row between

67 Wrightsville and Memorial Streets. The predominant use in the district, apart from Ammons Dare Corporation purchased the district is 5.7 acres in size and is 68.4 the State Park, is residential. There are 90 tract from HSL in early 1986. percent developed. lots which meet the Town’s development criteria for single-family homes with some On July 16, 1986, the Town approved the SPD-20: Special Planned Development vacant parcels within or adjacent to Jockey’s Master Plan and Development Standards for District Ridge State Park. The Village at Nags Head. This Master Plan established development and density The Special Planned Development District standards for The Village at Nags Head, five was created to permit development SED-80: Special Environmental District single-family designations, three multi- compatible with the environmentally The SED-80 District includes Nags Head family designations, two hotel districts, two sensitive nature of the unique coastal land Woods, an irreplaceable maritime forest that commercial areas, a beach and tennis club, a forms contained in this district. The largest occupies the northwest corner of Nags Head, golf course, sound access areas, Sea Pointe portion of this district contains Jockey’s and one of a few remaining maritime forests duplex standards, and numerous areas Ridge State Park that has been designated by in North Carolina. Nags Head Woods was designated as open space. The Master Plan the North Carolina Coastal Resources recognized for its environmental significance also established standards for an institutional Commission as a unique coastal in 1974 when it was designated a National district and Townhouse 1 District standards. geologic formation area of environmental Natural Landmark by the US Congress. concern and as a National Natural While multi-family and hotel standards were Landmark by the United States Department SPD-C: Special Planned Development- developed, no multi-family or hotel of the Interior. Community District buildings (other than the Quay, which was

The Town has one SPD-C District, the built before 1986) have been built. The The northwestern portion of the district Village at Nags Head. The Village located residential density has been less than what borders on Nags Head Woods. This district between the Atlantic Ocean and Roanoke was originally approved in the 1986 Master is characterized by unique topographical and Sound, with Old Nags Head Cove Plan. vegetative features including vegetated and subdivision to the north and Forrest Street unvegetated dunes, migrating sand dunes to the south. There are approximately 373 To date, there are 598 lots created for and a pine forest. acres in SPD-C. residential (single-family and duplex)

development. Of those 598 lots, 218 remain There is one SPD-20 District that Planning for The Village at Nags Head undeveloped. In addition, parcels L-1 and L- encompasses the North Ridge subdivision, Special Planned Development-Community 2, between the Outer Banks Mall and Old the Villa Dunes subdivisions (west of the District began in the 1970’s. The original Nags Head Cove, which have not been Outer Banks Worship Center) and the Villas plan was amended and adopted by the Nags subdivided, are the last remaining residential Townhouses as well as and Jockey’s Ridge Head Board of Commissioners on June 1, parcels. The approved Master Plan allows State Park. 1981. At this time, the land was under the for a maximum of 101 dwelling units on

ownership of the Epstein family and was these parcels. In addition to the undeveloped The SPD-20 District is 534.6 acres in size known as the “Epstein Tract.” The Epstein residential lots, there are three undeveloped with 417 acres in public and governmental heirs sold the tract to Home Savings and parcels (6.7 acres) in the Commercial 1 ownership (Jockey’s Ridge State Park). The Loan of Rocky Mount (HSL) in 1984. The

68 District and 9 undeveloped parcels (9.4 recreational value that these waters provide units constructed per year. Using this figure, acres) in the Commercial 2 District. The to the Town, its residents, visitors and the 1,560 lots remaining for single-family Small Hotel Parcel (6.1 acres) also remains surrounding area. development would be used up in 14.3 undeveloped. years. Following the growth patterns Uses allowed within this district include: observed over the last twelve years, an The Village at Nags Head currently has non-commercial recreational activities, additional 1,834 dwelling units will be architectural review standards, a State- commercial recreational activities that are added, giving a total of 6914 dwelling units approved stormwater control plan and land based in Nags Head, single-family assuming that there are no changes in zoning buffering and vegetation standards. The dwellings, piers and docks and other which would affect development intensities. 1986 Master Plan has been amended and customary accessory uses. There are There are currently 178 acres in the various became part of the Town’s Zoning currently three “fish camps” or single-family commercial districts that can accommodate Ordinance on November 3, 1993. dwellings on islands in Roanoke Sound future growth. Based on previous within the ETJ area that have existed for a development patterns, this land will be Ocean and Sound Waters Zoning number of years. developed in twelve years (Nags Head, District-Extraterritorial Jurisdiction 2000).

(ETJ) Population As Nags Head continues to grow and The General Statutes of the State of North Nags Head was incorporated in 1961 and in develop, the size of its peak population Carolina allows municipalities to extend 1970, there were only 414 permanent will grow as well. An analysis of land zoning and planning jurisdiction into residents in the Town. By 1980 the availability, permissible development unzoned county areas up to one mile beyond population had more than doubled, and in and building trends is used to estimate their municipal boundaries. Nags Head has the years between 1980 and July l, 1985, the extent of future peak population and the established extraterritorial jurisdiction one permanent population increased an demands that will be placed upon the mile out into the Atlantic Ocean, one mile additional 80 percent. The 2000 permanent natural and man-made environments in the west of the Town’s estuarine shoreline, one population of Nags Head is 2,700 - a 46.9% Town. mile south of US 64-264 on the Causeway, increase since 1990 - and the permanent and one mile west of the Town boundary population is projected to be around 3,580 The likely peak population that would result line in South Nags Head. With the in the year 2020 (OSP, 2001; Nags Head, from maximum build-out, based on existing exception of land within the Cape Hatteras 2000). Under existing development, the land uses, is estimated to be between 51,324 National Seashore and some islands in the peak daily summer population is estimated and 66,584 (Nags Head, 2000). sound, the remainder of the ETJ area is to exceed 34,500 people. water. Transportation Projected Development and The Ocean and Sound Waters District was The existing transportation system in Nags Population Trends established to provide for the use of the Head consists of two primary, shore-parallel ocean and sound waters, including islands, Over the last 22 years there have been an roads. NC 12, which is closest to the ocean, that adjoin the Town to ensure the average of 109 single-family dwelling is also known as Virginia Dare Trail and the continued scenic, conservation and “Beach Road.” US 158 generally runs down

69 the center of Town and is known as erosion in excess of 100 feet are not Hazardous Events/Processes Croatan Highway and the “Bypass.” uncommon. In addition to these two roads, which are Historic Storm Impacts state maintained, there are numerous town- Geology/Morphology Hurricanes and severe coastal storms maintained roads running in an east-west represent serious threats to life and property configuration that connect NC 12 and US The geologic framework, physical dynamics, in Nags Head. Between 1890 and the 158. In South Nags Head, south of and recent human modification dictate the present, North Carolina experienced 24 Whalebone junction, NC 1243 (South Old types of barrier islands that constitute the hurricanes, or an average of approximately Oregon Inlet Road) is a state-maintained Outer Banks and their evolutionary one hurricane every four years. In addition road and the only major road within Nags development. to hurricanes, Nags Head is also subject to Head that serves this area. tropical storms and northeasters, such as the Sediment-rich coastal segments previously devastating Ash Wednesday storm of 1962 The NC Department of Transportation has formed as complex barriers consisting of and Tropical Storm Dennis in 1999 that completed a Thoroughfare Plan for the multiple seaward prograding beach ridges lingered off the Nags Head coast for a week Outer Banks and suggests the following result in high, wide islands. Today, these before eventually making landfall south of changes to facilitate traffic movement within complex islands are neither migrating Nags Head. the Town (specifically along NC 12): landward nor accreting seaward; rather, erosion is the dominant process on both In an attempt to keep the beaches free of 1. Improve NC 12 with by an additional three feet of ocean and estuarine shorelines. debris, the Town can declare structures pavement on both sides. which are storm damaged and in danger of 2. Where there is currently a third turn lane on NC 12, Sediment-starved coastal segments formed as collapsing a public nuisance. In addition, the interconnecting road to US 158 should be simple overwash barriers consisting of thin any structure which is located in whole or widened to three lanes. Holocene sand perched on the interstream part in the public trust area can be declared a 3. Gull Street and Lakeside Street should be three divides of Pleistocene drainage basins. Due public nuisance and abatement procedures lanes from NC 12 to US 158. A signal should be to the geologic inheritance and evolutionary can be initiated by the Town. placed at Gull Street to address access to the development, some of these sediment- Soundings Shopping Center. starved barriers are presently collapsing with little chance of surviving in their present Hazard Geoindicators Shoreline Changes form. As previously discussed, hazard geoindicators Erosion rates vary widely along the Atlantic Reconnaissance studies of the thick are local geomorphologic features that can, coastline of Nags Head. Average erosion Quaternary section on the continental shelf and do, influence coastal processes and their rates for various sections of the beach range adjacent to the Outer Banks have impacts. The primary hazard geoindicators from two feet per year at Eighth Street to ten demonstrated numerous potential sand found in Nags Head include: feet per year at the southern Town limits in resources that occur in paleofluvial deltas South Nags Head. These rates are long term and channels, cape- structures and averages and acute, episodic events that cause various stratigraphic lithofacies (Riggs, 2001).

70 Topographic Geoindicators The VE-zone is 628 acres in size and structures, with a tax value of $254,964,860 encompasses approximately 635 developed as of January 1, 1997. Of these 1,429 Elevation parcels on 534 acres. The total tax value for structures, 489 structures had a tax value Nags Head has four flood zones, two of these developed parcels was $236,887,019 as $166,201,000 and were built prior to the which are on the oceanfront. Each flood of January 1, 1997. Of the 635 structures, Town’s participation in the National Flood zone has its own development requirements 293 were pre-FIRM (before adoption of the Insurance Program (Nags Head, 2000). for new construction as well as requirements Flood Insurance Rate Maps) and built before for additions and improvements to existing the Town began to participate in the Vegetation structures. National Flood Insurance Program in 1978 Vegetation native to Nags Head includes (Nags Head, 2000). Spartina patens (cord grass), Ammophila VE-Zone/Special Flood Hazard Area breviligulata (American beach grass), Uniola This zone is the closest to the water and AE-Zone/100-year Flood/ paniculata (sea oats), Baccharis halimifolia delineates areas of the Town that will be Special Flood Hazard Area These zones delineate areas in the (eea myrtle), Myrica cerifera (wax myrtle), subject to substantial wave action during a Iva frutescens (marsh elder), Quercus 100-year storm (areas subjected to surface community that have an annual probability of one percent of being flooded (areas that virginiana (live oak), Juniperus virginiana waves three feet high on top of already rising (red cedar), Slex vomitoria (yaupon) and waters). The VE-Zone constitutes a stretch will be inundated by the 100-year flood). These zones are located over almost all of the Spartina alterniflora (smooth cord grass). of oceanfront from the southern corporate limits to the northern borders of the Town. Town (Figure NH 2). Specifically, these areas include most of the The most significant area of maritime forest land east of NC 12 and is Nags Head Woods, one of the few NC 1243 (although there remaining maritime forests in North are V-zones along the Carolina. The Woods includes "the Fresh frontal dunes), much of Pond," large stable marshlands, large the land between NC 12 vegetated and unvegetated sand dunes, a and US 158, portions of forest with ponds, wetlands, pine land west of US 158 along hummocks, bay forest and hardwood and the estuarine shoreline pine forests. and Cedar and Pond To protect the Fresh Pond as a source of FIGURE NH 2 islands. potable water, the Town acquired 318 acres The AE flood zone is of land west of the pond in the 1960s. 2,158 acres in area of Conditions of the acquisition were that the which 1,453 acres are area remain as a watershed and that the area developed. Development not be subject to development. In 1987, the within the AE flood zones Town revised its Zoning Ordinance and is composed of adopted a comprehensive set of zoning approximately 1,429 regulations for the protection of Nags Head

71 Woods. These ordinances permit primarily Town is managed through a cooperative Bathymetry single-family housing and include agreement with the Nature Conservancy. The bathymetry of Nags Head is illustrated regulations to ensure that the function and in Figure NH 3 on the next page. Nags character of the maritime forest will be Shoreline Geoindicators Head is classified as mesotidal which means preserved. it has a moderate tidal range. Wave energy is Shoreline geoindicators include also moderate. geomorphologic features of the ocean beach, In 1992, the Town, in cooperation with The Nature Conservancy (TNC), purchased 386 the estuarine shoreline and the offshore acres in Nags Head Woods. This tract is continental shelf. This category of Ocean Overwash commonly referred to as the RTC tract, the geoindicators influences storm surge height, The Halloween storm of 1991, a northeaster Great Atlantic Savings Tract or the Tillett storm wave height, wave energy and storm that followed a late season hurricane, caused Tract. The property was acquired by the surge ebb flow. an erosive wave pattern that eroded Town and The Nature Conservancy to be significant dune areas and caused serious managed as a natural area and nature The Ocean Beach ocean overwash. Subsequent storms in the winter of 1992/1993, and the summer of preserve. Depending upon the time of year and the 1994 resulted in additional overwash as a occurrence of recent storms and result of dunes weakened in the Halloween When the property was acquired, the federal hurricanes, the beach (both wet and dry) storm of 1991. Some of the areas affected by government designated the tract as part of ranges from 100 feet wide to several the overwash drained relatively quickly, the Coastal Barrier Resources Act, and in hundred feet wide. In areas where there has while standing water affected some areas for doing so, federal flood insurance will not be been extensive sandbagging, the sandy beach a week or so. The flooding is currently available for any development that occurs in area can be non-existent during high tide. sporadic. The ocean overwash flooding this tract. In 1997, the Town offered Articles cannot be prevented but may be controlled of Dedication to the State of North Carolina For Nags Head there are a number of by a community-wide beach nourishment for most Town-owned property in Nags erosion rates for various sections of the beach program. Head Woods. The offer was accepted, and ranging from two feet per year at Eighth this area is now dedicated in perpetuity as a Street to ten feet per year at the southern nature preserve. Town limits in South Nags Head The Estuarine/Backside Shoreline The soundside shoreline of Nags Head is largely characterized by an eroding salt Nags Head Woods is included in the SED Primary/Frontal Dunes (Special Environmental District) 80 Zoning marsh, canals that were dredged to provide District. Of the 972 acres in the District, The foredune in Nags Head ranges from access to Bogue Sound and artificial fill used 303 are owned by the Town, 386 are jointly nonexistent to over twenty feet in height. for development. owned jointly by the Town and TNC and The dune in Nags Head is artificial, however, having been built during the Great 27.5 are owned by TNC. As a result, Inlet Geoindicators approximately 73 percent of the land in Depression by the CCC and WPA. Nags Head Woods is owned by the Town In any major storm or hurricane, the and TNC. Most of the land owned by the formation of new inlets is a possibility.

72 While the prediction of inlet formation and their precise location is highly uncertain, particular physical features can be used to identify likely sites. Three areas within the Town have been identified as possible sites for incipient inlets.

Whalebone Junction Incipient Inlet The area around Whalebone Junction is identified as a potential incipient inlet based on several factors including elevation, island width, canal dimensions and erosion rate.

Old Nags Head Cove Incipient Inlet A second potential inlet site is located in the Old Nags Head Cove area where finger canals have been excavated approximately 1,000 feet perpendicular to the soundside shoreline. In this location, storm surge from the sound has a relatively unobstructed FIGURE NH 3 pathway across nearly half the island.

Soundside Road Incipient Inlet A third potential inlet site is located in the Soundside Road area just south of Jockey’s Ridge State Park. This area has been identified because of its relatively frequent flooding. This area experienced extreme flooding and damage during the Ash Wednesday storm of 1962. Non-Shoreface Geoindicators There are eleven different soil associations found within Nags Head, most of which have some type of development limitations.

73 Mitigation Recommendations embraced the concept of allowing natural The primary coastal hazards in Nags Head barrier island processes, including shoreline include: Nags Head is low and flat with high migration, to occur and has supported the potential for damage from storm surge relocation/ demolition of threatened storm surge and overwash flooding flooding, wave attack, wind damage and new oceanfront structures as the preferred sand deposition from overwash inlet formation. The most widely response to buildings threatened by a flooding from falling/standing water distributed problem along the Nags Head migrating shoreline. oceanfront, in addition to erosion, are gaps Protect the integrity of the ocean Today, however, the town supports beach in the foredune. These gaps vary in size and beach and dune system and nourishment as the primary way to address frequency along the length of the Nags Head recognize the natural processes and oceanfront with some areas having virtually the problems caused by buildings that are no dune protection for several hundred located along a naturally migrating shoreline. dynamics of the shoreline. yards. This position is short-sighted, imprudent and directly contradicts the Town's previous The Town should strictly enforce its policy against sea walls, jetties, groins and other In addition to dune gaps, several public - and correct - conclusions regarding the inadequacies of beach nourishment. artificial devices designed to stabilize the beach access sites have resulted in blowouts ocean shoreline. Sandbags should only be of the dune. The resultant notches in the The single most important element of an allowed as temporary protection devices (no dunes may channel storm overwash and also more than two years) for imminently act as storm-surge ebb conduits. effective coastal hazard mitigation strategy for the town of Nags Head is for the town to threatened structures until they can be removed from the site or demolished. A passage from the Nags Head 1991 CAMA re-examine its stance on threatened oceanfront structures and to, once again, Land Use Plan reads, "Because most beach In addition to basic economic nourishment programs involve only the upper officially endorse a policy of relocation/ demolition. This will provide the Town with considerations, decisions concerning the use reaches of the beach, they increase its slope, and of potential sand resources for long-term can actually in some cases increase the rate of a successful, long-term, equitable and cost- effective way to address not only chronic beach management in Nags Head should erosion. Moreover, beach nourishment projects consider some significant parameters are typically very expensive and the results erosion, but also acute storm impacts. including the geologic framework variables temporary and require continual nourishment. controlling individual island formation and A single northeaster may eliminate much of the In addition to the need for the Town to revise its general policy regarding oceanfront evolution, regional high-energy wave and sand deposited under a nourishment program." storm climate, cumulative environmental erosion and development is a need for the town to addresses the vulnerability of consequences of sand and beach Although the town of Nags Head has taken nourishment, and the specific response of active steps to regulate development during existing and potential development, the existence of hazard geoindicators, hazardous each coastal segment to ongoing sea-level the past 20 years, it has made a significant rise. policy change regarding vulnerable and/or processes and other coastal hazards. threatened development along its oceanfront. Historically, the Town has

74 Implementing actions: • The Town should investigate innovative Develop a set of regulations, programs and seek funds for mitigation guidelines, and development review • Require dune crosswalks for all new oceanfront measures such as relocation of threatened development. structures from extreme hazard areas. processes that will help preserve • The Town should give high priority to the • The Town should acquire oceanfront property topography, vegetation and other preservation of dunes, vegetation and when the opportunity arises. natural characteristics. topography as an important hazard mitigation • The Town should investigate mitigation Existing land uses in the Woods are limited component. programs and grants to assist property owner in to nine residences and one former farm site. • Require any proposed development or the relocation of threatened structures. The current management system is to redevelopment to rebuild and revegetate dunes • The Town should take a more proactive protect environmentally sensitive features for the purpose of creating and maintaining a approach towards the condemnation of and the water supply. The marshes may fall continuous dune line along the oceanfront. damaged structures and issue civil citations under protection by the Coastal Resources • Consider annually, through the Capital when necessary. Commission through an AEC permit and/or Improvements Program process, providing by the Corps of Engineers permitting • Actively participate in the Federal Emergency funds for the acquisition of open space in high process. Management Agency Community Rating hazard areas along the ocean shoreline. System Program to develop mitigation Town zoning and land use regulations that Reduce the risks and vulnerability of measures to reduce or prevent flood damage are designed to prevent the filling of from occurring in the first place. structures to damage and loss from wetlands in certain areas should be enforced. • hurricanes and coastal storms in The Town should develop and implement a comprehensive Floodplain Management Plan Development near the Fresh Pond is limited advance of such events. and annually evaluate progress toward by the Zoning Ordinance and AEC The Town should actively endorse implementing the plan. regulations that restrict septic systems to one per acre within 1,200 feet of the edge of the relocation, demolition and acquisition as the • The Town should continue to encourage Pond. Septic systems are prohibited within preferred alternatives for addressing the relocation of structures that are threatened by 500 feet of the edge of the Pond. impacts of barrier island migration and erosion and Town Staff should actively work with ocean erosion upon existing structures. homeowners and Federal Emergency Management Agency to facilitate their Implementing actions: Implementing actions: relocation. • Develop a comprehensive Corridor Vegetation • The Town should incorporate recent erosion Enhancement Program. trends and increase minimum setback distances • Institute a program of land acquisition to acquire on all oceanfront lots land now to protect the visual integrity of the • The Town should sponsor studies to determine Town. the optimal approach for removing threatened • Develop a long-range program to place existing structures from the oceanfront shoreline. overhead utilities underground.

75 • Develop a visual enhancement program Protect the physical and visual • Develop an Open Space Plan designed to (landscaping, buffering, landscaped corridors) to identify key locations for land and easement protect and enhance the natural vegetation and integrity of the estuarine shoreline. acquisition. topographical features of the Town. Implementing actions: Consider higher flood regulatory • The Town should inventory open space, actively • pursue grants and funding opportunities and Actively pursue all sources of funding including standards for vehicle and develop and implement a plan to acquire and the Capital Improvements Program to provide equipment storage areas and preserve open space throughout the Town. funds for open space and estuarine access structures that produce, use or projects. • The Town should consider an incentive program store volatile, flammable, explosive, • to reward developers that set aside additional Develop ordinances which would exclude toxic and or reactive materials. open space in perpetuity development detrimental to the estuarine environment. Implementing actions: Investigate more stringent building Increase the amount of recreational codes for high hazard areas. • Develop a program to identify businesses and open space along the ocean and material storage areas where significant Implementing actions: estuarine shorelines and increase amounts of toxic or hazardous products are stored that could be subject to flooding. • The Town should investigate the feasibility of open space in other areas. • becoming a FEMA “Project Impact” community. The Town should develop regulations to require Implementing actions: fuel tanks, including LP tanks to be adequately • The Town should consider the applicability of anchored to prevent flotation or submersion in • requiring “V Zone” structural certification for Investigate the feasibility of implementing a the event of flooding. structures in the 100-year flood zone. facility fee schedule that will require payment of fees from new development that will be used for • The Town should consider amendments to the the acquisition of land for ocean and estuarine Flood Ordinance that address freeboard and access areas. recognize other flood mitigation measures by FEMA and the CRS program to reduce flood • Submitting grant applications for shoreline loses. access projects when the opportunities arise.

76 FIGURE NH 5

•

FIGURE NH 4

77 78 COMMUNITY CASE STUDY 3: NORTH TOPSAIL BEACH, NC

Community Overview island are areas of undifferentiated marsh, Development tidal flats and tidal creeks which are backed The town of North Topsail Beach makes up by Stump Sound at the town’s southern end North Topsail Beach was incorporated in approximately six square miles of the and the at the center 1990, and little change in the town’s northeastern end of Topsail Island, a 26-mile and northern end of the town. Stump Sound predominant land use patterns has occurred long northeast-southwest trending island in is a shallow lagoonal system that ranges in since this time. The town remains almost the North Carolina barrier island system width from .4 to 2.4 kilometers. The exclusively a residential community with (Figure NT1). North Topsail Beach is predominant littoral current at North 50% of all parcels designated for multi- bordered by the New River Inlet to the Topsail Beach is from north to south. family use, approximately 38% for single- northeast and the town of Surf City to the family, site-built structures and the southwest. remaining 10% dedicated to mobile homes. Only two percent of the town’s developed Two bridges provide parcels are classified as nonresidential use access to the (NTB, 1996). island—a swing bridge in Surf City The southern half of North Topsail Beach to the south and a was developed before the northern half high-rise bridge that because access to the island was available via connects North NC 210. The older, southern end of the Topsail Beach to the town was developed without any land use mainland. A single controls and, as a result, contains a mixture main road runs of manufactured homes, site-built single- parallel to the ocean family homes, duplexes, quadraplexes and along the length of FIGURE NT 1 condominiums constructed at varying the island with some densities. shore-perpendicular roads that run from Much of the northern half of North Topsail the ocean to the Beach was developed after 1982 and is sound or dominated by high density condominiums, Intracoastal duplexes and quadraplexes. Road access to Waterway. this area has been, and continues to be, a Landward of the significant factor that influences development north of the NC 210 bridge.

79 More than 120 homes were destroyed in Transportation Issues The primary transportation issue facing North Topsail Beach as a result of Hurricane North Topsail Beach continues to be from Bertha in July, 1996, and more than 50% of Topsail Island is served by two bridges. The overwash, especially on SR 1568 near the oceanfront lots in North Topsail Beach Highway 210 Bridge was built in 1968 and Galleon Bay. During Hurricane Fran a new were totally lost or rendered unbuildable as a has a design capacity of 12,000 vehicles per inlet was formed in this area connecting Old result of erosion caused by Hurricane Fran day in each direction. This bridge is Sound Channel and the Atlantic Ocean. in September, 1996. considered to be in good condition by the This section of SR 1568 requires above NC Department of Transportation. The average maintenance in order to remain Projected Development Trends draw bridge at Surf City is very narrow and functional due to its proximity to the can only carry two-way traffic if not being Although the entire town is accessible to Atlantic Ocean. crossed by a truck (at which time it is only water and sewer service, future growth will one-way). The capacity of the Surf City be restricted by a lack of additional pumping In less than 2 miles, SR 1568 crosses 10 bridge depends on how often it is open. capacity, inadequate pressure problems, small bridges that span marsh fingers, some potential water quality problems and of them with open water. Before Fran and Highway 210 from the high-rise bridge inadequate sewer system treatment capacity. Bertha, some of these “fingers” reached south to the Pender County line is the only nearly to the back of the dune, effectively primary roadway within North Topsail In addition, approximately half of the town reducing the width of the island. During Beach. This section of highway is seven miles is designated within a Coastal Barrier Fran and Bertha, these fingers acted like long and has a typical 20 to 24-foot section Resources System Area (CBRA) and is conduits for storm surge, ripping up width with a 60 to100-foot wide right-of- therefore ineligible for federal flood pavement and making the road nearly way. State Road 1568 from the high-rise insurance. Private flood insurance, however, impassable. bridge north has a typical section width of remains available in these areas. 18 feet and a 60-foot right-of-way. Average Most of the road along North Topsail Beach daily traffic on SR 1568, just north of the east to Bay Court has been relocated back Population high-rise bridge, exceeds 3,400. Average from the beach a few yards toward the center The 1999 population of North Topsail daily traffic on Highway 210, just south of of the island, but to a lower elevation. Beach was 1,139 which represents an the high-rise bridge, exceeds 4,100 (NTB, increase of 20.3% from 1990. The 1996). A similar situation exists from Bay Court population of the town is estimated to be into the rest of the North Topsail Beach area 1,343 in 2005 (OSP, 2001). The town’s At the northern end of town, the public where erosion has forced the relocation of peak seasonal population is approximately roadway ends and poorly-maintained private the road all the way to Marine Drive. 12,000, with an additional 6,000 day visitors streets provide the only means of ingress and on the Fourth of July and Labor Day (NTB, egress for a substantial number of residential Shoreline Changes 1996). units. At the southern end of town, many streets in the Ocean City and family The shoreline of North Topsail Beach campground remain unpaved. consists of 12 miles of Atlantic Ocean shoreline and approximately 14 miles of sound and estuarine shoreline (FEMA,

80 1996). Both the front and back shorelines about 60 feet thick near North Topsail Hurricanes Bertha and Fran in 1996 and have been dramatically altered over the past Beach. The Castle Hayne Limestone Floyd in 1999 had profound impacts upon five years by several hurricanes including Formation of Eocene age underlies the North Topsail Beach. In addition to the Bertha (1996), Fran (1996) and Floyd Yorktown Formation and the Pee Dee transportation impacts already described, (1999). Formation of Cretaceous age underlies the Fran cut three deep storm-surge ebb scour Castle Hayne Formation. channels approximately two-thirds of a mile Prior to Hurricanes Bertha and Fran, the south of the Roger’s Bay Campground. town’s frontal dune system north of the There are eleven soil types in North Topsail high-rise bridge consisted of 10 to 15-foot- Beach, each possessing some type or degree These channels scoured the road and high ridges. The entire frontal dune system of development limitation. undercut the foundations of at least two was completely demolished by Fran, buildings. Two of the channels lined up with although several attempts have been made to Hazardous Events and Processes shore-perpendicular navigation channels cut artificially re-establish them. The frontal into the marsh and the driveways that faced dune in this area now consists of North Topsail Beach is subject to hurricanes, them. This lineation indicates that these discontinuous, sparsely-vegetated bulldozed tropical storms and extratropical cyclones. shore-perpendicular features channeled water dunes that range in height from 0 to 10 feet. The hazardous processes of interest in North and enhanced scouring. Topsail Beach are storm surge, storm Before Fran, the dunes south of the high-rise overwash, storm surge ebb, erosion and High watermark elevations for Bertha ranged bridge were discontinuous, Where they were wind. from 3.9 to 6.0 feet NGVD behind the present, the dune field consisted of a single island to 9.3 feet NGVD along the Atlantic discontinuous ridge, 13 to 23 feet wide and Historic Storm Impacts Ocean shoreline. High watermark elevations generally no higher than 11.5 feet. The dune In 1954, Hurricane Hazel generated a storm for Fran ranged from 8.1 feet NGVD is now largely absent with some surge of 9.5 feet and destroyed 210 of the behind the island to 11.5 feet NGVD along discontinuous sand mounds that were 230 homes on the island. Hazel caused an the Atlantic Ocean shoreline (FEMA, 1996). established by dumping sand on the beach estimated $2.5 million (in 1954 dollars) after Hurricane Floyd. worth of property damage on Topsail Island Hazard Geoindicators and destroyed the Surf City drawbridge Geology/Morphology (Pilkey, 1998). As previously discussed, hazard geoindicators are local geomorphologic features that can, The Pamlico Surface is at sea level to 34 feet A 1987 evaluation of the island by the NC and do, influence coastal processes. The in elevation and covers a narrow strip near Division of Emergency Management primary hazard geoindicators found in the coast including North Topsail Beach. correctly indicated that the island would be North Topsail Beach include: largely underwater in a category 1 or 2 The unconsolidated surface sediment is hurricane, and nearly completely submerged about 30 feet thick in North Topsail Beach. in a category 3 hurricane. The Yorktown Formation of Miocene age underlies the surficial sediment unless it has been removed by erosion. This formation is

81 Topographic Geoindicators Cedar Bush Cut Island at the northern end Shoreline Geoindicators of North Topsail Beach where the Elevation Intracoastal Waterway joins the New River. Shoreline geoindicators include The majority of North Topsail Beach lies at Both sites are unsuitable for development geomorphologic features of the ocean beach, an elevation of ten feet above mean sea level and have been classified as conservation the estuarine shoreline and the offshore or less with an average elevation of 9 feet. zones by the town. Except for the dunes, continental shelf. This category of Because of its low elevation, the entire slopes throughout the town are generally geoindicators influences storm surge height, community lies within the 100-year below 12 percent (NTB, 1996). storm wave height, wave energy and storm floodplain (Figure NT 2). surge ebb flow. Vegetation All oceanfront properties and property Vegetation type and density varies along the The Ocean Beach bordering the New River are at least partially town’s length with the area near the New The average, long-term erosion rate in North classified as being in an NFIP V-zone. All River Inlet almost completely void of any Topsail Beach ranges from 2 to 5 feet/year sound-side properties adjacent to the V-zone vegetation. Areas of intact maritime forest north of the high-rise bridge to about 2 are classified as being in the A-zone. Only are located north of New River Inlet Road feet/year south of the high-rise bridge two small pockets of land are classified as B- and on the landward-side of Highway210 (Pilkey, 1998). The beach currently ranges zone properties - a sand dune located on south of the high-rise bridge. The remainder in width from 10 to 120 meters from the Permuda Island and an elevated rise on of the town is vegetated by sparse shrub and dune line to the high water line. grass (Pilkey, 1998). Vegetation native to North Primary/Frontal Dunes Topsail Beach includes The frontal dune south of the high-rise Spartina patens (cord grass), bridge consists of a discontinuous, Ammophila breviligulata unvegetated sand dike that ranges in height (American beach grass), from 0 to 15 feet. This artificial dune line Uniola paniculata (sea oats), was constructed in September, 1999 using Baccharis halimifolia (eea overwash sand deposited by Hurricane myrtle), Myrica cerifera Floyd. Sand was removed from streets and (wax myrtle), Iva frutescens parking lots and stockpiled in the parking lot (marsh elder), Quercus of the old Ocean City Pier. This sand was virginiana (live oak), screened and returned to the beach by dump Juniperus virginiana (red truck. cedar), Slex vomitoria (yaupon) and Spartina North of the high-rise bridge, the dune line alterniflora (smooth cord FIGURE NT 2 varies considerably. There is no dune just grass). north of the NC 210-SR 1568 intersection, at the Onslow County PBA, immediately south of the Villa Capriani Resort and north

82 of the Topsail condominium complex. A well-vegetated, discontinuous dune line 6 to 10 feet in height exists just south of the Onslow Beach PBA, just north of Salty’s Pier and between the St. Regis Resort and Topsail Reef condominiums. FIGURE NT 3

Bathymetry The bathymetry of North Topsail Beach is illustrated in Figure NT 3 on the next page. North Topsail Beach is located on the western edge of Onslow Bay, a large coastal embayment that stretches from Cape Lookout, NC to Cape Fear, NC. Onslow Bay is a high energy (1m average wave height) microtidal system typified by an abidance of rock outcrops of Tertiary to Quaternary.

The Onslow Bay shelf is sediment-starved and the introduction of new sediment to Onslow Bay is negligible due to: 1) no fluvial input (coarse sediments are trapped in the upper estuarine system) and 2) minimal sediment exchange between adjacent shelf. Much of the offshore area is dominated by NORTH TOPSAIL BEACH Oligocene limestones and siltstones mantled with a patchy, thin veneer of interbedded muddy sands and shell units (Cleary, 2001).

The dominant direction of wave approach is from the northeast during the winter months, and from the southeast during the summer Typically, storm waves approach from the northeast, but the area is also subject to episodic storm wave events from the east and south during the passage of

83 tropical and extra tropical cyclones. Hindcast 5) A small stretch just north of the Onslow Historical charts indicate that the inlet has wave data (WIS studies) indicate a mean County PBA migrated within a 2-kilometer zone since wave height of 1.1 meters, with a 7 second 1856. The migration-zone width for the period. The dominant direction of wave In general, those areas that did not inlet is controlled by the ancestral channel of approach is from the southeast. The net experience overwash were fronted by a the New River, the majority of which is is to the southwest. relatively continuous, well-vegetated dune located on the Onslow Beach shoulder. line in excess of 6 feet in elevation. Storm Surge In recent history, the width of the inlet has The maximum estimated 100-year storm The Estuarine/Backside Shoreline fluctuated from a minimum of 66 meters in stillwater surge elevation for North Topsail The soundside shoreline of North Topsail 1938 to a maximum of 382 meters in 1987. Beach is 12.4 feet (including wave setup of Beach is largely characterized by an eroding Over the past 60 years, the average width of 2.1 feet). In 1996, Hurricane Fran produced salt marsh and marsh canals and channels the inlet has been 225 meters. Maintenance a storm surge of 12 feet in North Topsail that were dredged to provide access to dredging of the inlet began in 1963. Prior to Beach. The maximum 100-year wave crest Stump Sound and the Intracoastal this time, inlet migration rates averaged 14.5 elevation is 19 feet (FEMA, 1996). Waterway. meters per year. Since 1963, the migration

rate has decreased to 3.8 meters per year Storm Overwash (Cleary, 1999). March 8, 1993 North Topsail Beach experienced extensive Inlet Geoindicators storm overwash during Hurricanes Bertha, North Topsail Beach has several inlet hazard The US Army Corps of Engineers currently Fran and Floyd. Significant overwash areas including the New River Inlet, areas maintains the New River Inlet channel occurred along most of the length of the where past inlet activity has occurred and which helps to stabilize the northeastern tip town during Floyd. In areas where areas where future inlet activity may be of North Topsail Beach. This area, however, development did not interfere with the expected. is extremely low and much of it is a state- washover process, sediment covered SR 1568 designated inlet hazard zone. and Highway 210 and was deposited into the backside marsh. The only areas that did New River Inlet not experience any measurable overwash New River Inlet (Figure include: NT 4) separates North FIGURE NT 4 Topsail Beach to the 1) The Surf City Campground southwest from military- 2) A small stretch just north of the NTB owned Onslow Beach to Fire Station the northeast. The inlet has 3) A small stretch just north of the Rogers generally moved to the Bay Campground southwest, although it 4) The residential area extending from just periodically has moved south of the high-rise bridge south to northeast. just north of the St. Moritz resort

84 Further, oceanfront erosion trends are Ten other potential inlet or swash sites are resources and recent storm impacts. From a related to the changing shape of the ebb-tidal located at the small bridges along SR 1568 geologic perspective, North Topsail Beach is delta, which in turn is governed by the north of the high-rise bridge. These areas are the most vulnerable coastal community in orientation of the ebb channel. During the highly susceptible to inlet formation during North Carolina and the only mitigation period 1962 to 1982, for example, 115 even moderate storms (Figure NT 6). recommendation that can be made with any meters of accretion were recorded along a 1- degree of confidence is for the town to kilometer stretch of oceanfront on North Non-Shoreface Geoindicators develop and implement a short- and long- Topsail Beach. Since 1990, however, this term retreat/relocation plan. area of North Topsail Beach has been There are eleven different soil associations dominated by erosion (Cleary, 1999) found within North Topsail Beach, all of In light of the fact that such a which have some type of development recommendation is likely to be disregarded Future Inlets limitations. by the community, the following hazard

A potential inlet site in North Topsail Beach mitigation recommendations are being is located perpendicular to Tradewinds Mitigation Recommendations presented in an effort to minimize storm Drive at Galleon Bay (Figure NT 5). A impacts to existing development. channel formed in this location during Hazard mitigation recommendations for Hurricane Fran that connected Old Sound North Topsail Beach are extremely limited Channel to the Atlantic Ocean. There is due to low elevation, the narrowness of the currently a bridge here. island, the community's proximity to New River Inlet, the lack of adequate sediment

FIGURE NT 6

FIGURE NT 5

85 Preserve the integrity of the ocean, for the purpose of creating and maintaining a threatened" structures and lots with substantially continuous dune line along the oceanfront. damaged structures. All publicly-owned lots beach and dune system and • should remain as permanent open space. recognize the natural processes and Plug all dune gaps and prevent the creation of new gaps. • The Town should develop a retreat/ dynamics of the shoreline. relocation/evacuation plan for the entire • Construct dune crossovers, both pedestrians community Even though North Topsail Beach is located and vehicular, where access to the beach is in a sediment-poor region of the NC coast desired. • The Town should investigate mitigation and little sand is available to establish and programs and grants to assist property owner in • Allow sand, deposited by storm surge and storm maintain a broad beach for storm protection the relocation/ demolition of threatened overwash, to remain in place. purposes, the town is currently investigating structures. the feasibility of a federal shoreline • protection project. Should this study The Town should sponsor studies to determine conclude that a federal project is not feasible Reduce the risks and vulnerability of the optimal approach for removing threatened structures from the oceanfront shoreline. in North Topsail Beach, the town should structures to damage and loss from • consider the following alternatives. hurricanes and coastal storms in The Town should take a more proactive approach towards the condemnation of General Implementing Actions: advance of such events. damaged structures and issue civil citations • The Town should strictly enforce the state's The Town should actively endorse when necessary. policy against sea walls, jetties, groins and other relocation, demolition and acquisition as the artificial devices designed to stabilize the ocean preferred alternatives for addressing the shoreline. impacts of barrier island migration and Protect the physical and visual • Allow sandbags only as temporary protection ocean erosion upon existing structures. integrity of the estuarine shoreline. devices for no more than two years and only for imminently threatened structures until they can Implementing actions: Implementing actions: be removed from the site or demolished. • • The Town should incorporate recent erosion Actively pursue all sources of funding including • Construct and maintain a continuous trends and increase minimum setback distances the Capital Improvements Program to provide frontal/primary dune field along the entire on all oceanfront lots funds for open space and estuarine access oceanfront of Atlantic Beach using compatible projects. sand from an off-island source. • Increase building density and building size • restrictions on all lots. Develop ordinances which would exclude • Increase the volume of any existing frontal/ development detrimental to the estuarine primary dune field using compatible sand from • The Town should prevent development within environment. an off-island source. 500 feet of existing overwash or swash channels. • Establish dune vegetation using native species. • The Town should establish a program to fund • Require any proposed development or the purchase of lots containing "imminently redevelopment to rebuild and revegetate dunes

86 FIGURE NT COMMUNITY CASE STUDY 4: CAROLINA BEACH, NC

Community Overview Development roads. In 1886, citizens organized the New Hanover Transit Corporation that erected a Carolina Beach, located at 34:02:06 N Carolina Beach began to develop toward the pier just south of Snow’s Cut on the Cape 077:53:38 W, comprises a low-lying, narrow end of the nineteenth century. In the early Fear River. From here, passengers arriving by spit of sand backed by a narrow marsh that is 1880s, the only means of transportation to steamer from Wilmington were transported attached to the mainland near Atlantic the beach was by way of poorly paved shell to the beach by a narrow gauge railroad. By Avenue. Carolina Beach correlates to two 1890, several large hotels and numerous natural divisions in its shoreline. From make-shift cottages dotted the beach. Carolina Beach Inlet to the vicinity of the Carolina Beach City Hall, the coast is that of Development prior to 1925 was relatively a barrier island backed by a narrow sound. slow. In 1954, Hurricane Hazel destroyed The area from the City Hall through the first brick hotel - built in 1924 – at the Wilmington Beach is attached to the corner of Ocean Blvd. and South Carolina mainland without the intervening sound, has Avenue. partial forest cover and elevations above the 100-year storm surge flood level (Pilkey, Approximately 45% of all housing units in 1987). Carolina Beach are either single family residences or duplexes, 53% are multi-family Carolina Beach is bordered to the north by units and 2% are mobile homes. Carolina Beach Inlet and by the town of Kure Beach to the south. The Carolina Over the last 30 years, Carolina Beach has Beach shoreline has a north-northeast, evolved from a predominantly vacant south-southwest alignment. The landscape to a predominantly developed predominance of wave energy components community. Rapid and uncontrolled in Carolina Beach is from the northeast development in Carolina Beach has resulted quadrant which produces a dominant in narrowed dunes, filled marshlands, finger southward littoral transport. Coquina rock canals and removal of most native vegetation fragments, originating in the vicinity of Fort (Pilkey, 1998). During this time, significant Fisher to the south, have been found along areas of Bogue Sound were bulkheaded and the Carolina Beach shoreline which indicates filled, and a significant amount of some littoral transport to the north (US development took place on small lots Army, 1962). unsuitable for septic systems.

87 During the 1980s, construction in Carolina Transportation Issues (Connie, Diane and Ione) and the entire Beach was dominated by multi-family units. project lasted only 7 months (Cleary, 1977). Since that time, single-family units have Highway and street system improvements become the leading type of dwelling unit are the most important transportation During September and October 1956, constructed (Carolina Beach, 1996). infrastructure issues in Carolina Beach approximately 200,000 cubic yards of The 1995 construction value for all (Carolina Beach, 1997). material was pumped on the beach. In residential dwelling units was $2,644,721. November 1956, 12 groins were constructed th Today, Carolina Beach is a mixture of Shoreline Changes between Wilmington Beach and 16 Avenue commercial and residential uses that are in Carolina Beach. primarily seasonal and resort oriented. From 1857 to 1938, the average annual recession of the mean high water shoreline in In 1962, the US Army Corps of Engineers Carolina Beach was 2.3 feet. The average Projected Development Trends described the erosion of the beach annual recession of the shoreline from 1940 During the next 20 years, public land use immediately south of the Carolina Beach to 1955 was 14.7 feet per year. From 1952 Inlet as “substantial” and authorized a changes in Carolina Beach may include to 1977, the erosion rate along the northern redevelopment of the “circle” and shoreline protection project that would portion of Carolina Beach averaged 40.2 feet eventually include 14,000 feet of beach in construction of a central sewer treatment per year (Cleary, 1977). and collection system. These changes will Carolina Beach. The project commenced in 1965 when 3,500,000 cubic yards of likely increase property values, promote the Early in 1955 a discontinuous dune ridge conversion of existing mobile home parks to material was pumped onto the beach from was constructed along the shore from Myrtle Grove Sound and the Intracoastal permanent residential dwelling units, Carolina Beach south to Fort Fisher. Sand increase traffic congestion and allow for the Waterway (US Army, 1962). Additional was obtained by dredging 252,000 cubic sand was pumped on the beach in 1967, dispersion of commercial development. yards of sand from Myrtle Sound near the 1970 and 1971. A 1,100 foot granite channel. Additional sand was bulldozed boulder seawall was built in 1970 and Population from the foreshore zone to the dune line. extended an additional 950 feet in 1973 The dune ridge was broken by numerous The permanent population of Carolina (Cleary, 1977). drainage channels, buildings and the Beach, as of July, 1999, was 5,139. This Carolina Beach boardwalk. represents a 41.6% increase since 1990 and a The current average annual long-term

209% increase since 1970 (OSP, 2001). The erosion rate in Carolina Beach is difficult to In June 1955, a rubble concrete groin was permanent population of Carolina Beach is determine due to the ongoing beach completed at the foot of Hamlet Street, projected to grow another 20% to 6,160 by nourishment project. about 300 feet south of the boardwalk. The 2010. The estimated peak overnight groin was 100 feet long and 12 feet wide at a population of Carolina Beach is estimated to Geology/Morphology crest elevation of 8 feet above mean low exceed 17,000 and the estimated peak day water. Both the groin and constructed dune population is estimated to exceed 40,000 The Pamlico formation is a low, nearly level ridge were completely demolished in the (Carolina Beach, 1997). terrace at an elevation less than 25 feet above summer of 1955 by three hurricanes present sea level. The materials in this formation are fine sandy loams, clays, sands

88 and some gravel. Deposits of recent age Historic Storm Impacts and Fran impacted the town within a few overlie the Pamlico formation. These include Many hurricanes have pounded this section months of each other. Fran produced a tidal marsh, beach sands and dunes. In of the North Carolina coast, but it was not stillwater level of 11.1 feet while Bertha marsh areas, the soil consists largely of until the 1890s that storm accounts began to produced a storm surge of about 5 feet accumulations of peaty matter. The make mention of this area. Carolina Beach (NOAA, 2001). The last major storm to thickness of the deposits varies from 15 to was struck by a severe storm in 1893 and in impact Carolina Beach was Hurricane Floyd 25 feet. 1898, the Navy lookout station was in 1999 which caused a storm tide (water destroyed by heavy storm surf. A year later, height above National Geodetic Vertical Hazardous Events and Processes numerous resort cottages were washed away Datum or sea level ) of 10.3 feet on nearby or damaged. Masonboro Island. (NOAA, 2001). Carolina Beach is subject to hurricanes, tropical storms and extratropical cyclones The most destructive storm of the first half Hazard Geoindicators and has been directly impacted by at least 10 of this century was probably that of August major hurricanes in the past 60 years (four in 1, 1944 when Carolina Beach incurred some As previously discussed, hazard geoindicators the past five years). The hazardous processes of the heaviest damage of the entire North are local geomorphologic features that can, of interest in Carolina Beach include storm Carolina coast. Two piers were destroyed, and do, influence coastal processes. The surge, wave action, storm overwash and trees were blown down and the water rose primary hazard geoindicators found in wind. high enough to flood second-story levels. Carolina Beach include: In 1954, Hurricane Hazel destroyed over 370 Topographic Geoindicators FIGURE CB 2 buildings, damaged over 700 others and produced a Elevation high-water mark of 13 feet The average elevation of Carolina Beach is above mean sea level along five feet above sea level (US Census, 2001). the Carolina Beach Because of its low elevation, a significant oceanfront. Less than a portion of the town is located within the year later, Hurricanes FEMA 100-year flood zone (See Figure CB Connie and Diane caused 2), and most of the town will be inundated additional damage, and in by a category 3 hurricane (Carolina Beach, 1959 Hurricane Grace 1996). flooded the town (Pilkey, 1978). Vegetation Carolina Beach Vegetation native to Carolina Beach includes experienced a relatively Spartina patens (cord grass), Ammophila tranquil period until 1996 breviligulata (American beach grass), Uniola when Hurricanes Bertha paniculata (sea oats), Baccharis halimifolia (eea myrtle), Myrica cerifera (wax myrtle),

89 Iva frutescens (marsh elder), Quercus Bathymetry virginiana (live oak), Juniperus The bathymetry of Carolina Beach is virginiana (red cedar), Slex CAROLINA BEACH illustrated in Figure CB 3 on the next page. vomitoria (yaupon) and Spartina Carolina Beach has a normal tidal range of alterniflora (smooth cord grass). approximately 4.2 feet and is classified as mesotidal. Wave energy is moderate. Shoreline Geoindicators The shoreface off of Carolina Beach is Shoreline geoindicators include sediment starved and dominated by hard geomorphologic features of the rock outcrops called hardbottoms. Several ocean beach, the estuarine hardbottom morphologies occur depending shoreline and the offshore on the lithology of the units outcropping on continental shelf. This category of this shoreface. Three rock types exist on the geoindicators influences storm subaerial headland shoreface: Pleistocene surge height, storm wave height, Coquina, Plio-Pleistocene Limestone, and wave energy and storm surge ebb Oligocene Dolosilt. flow.

Hardbottoms are either high relief (>0.5m) The Ocean Beach or low relief (<0.5m). High relief Since 1955, at least 20 sand hardbottoms consist of scarps and overhangs pumpings have been necessary to and are typically encrusted with organisms hold the shoreline in place, and the such as , mollusks, and beach in front of the stone bryozoans. Lower relief hardbottoms are revetment at the north end of intermittently covered with sand sheets and Carolina Beach has experienced have minor amounts of encrusting rapid loss of nourishment sand. FIGURE CB 3 organisms. Low relief hardbottoms are the The average, long-term erosion rate dominant type on this shoreface. in Carolina Beach is approximately 2 feet/year (Pilkey, 1998). Hardbottoms contribute sediment to the shoreface sediment budget through Primary/Frontal Dunes biological and mechanical erosion. Dunes are discontinuous, low and Organisms and storm and wave processes narrow with sparse vegetation serve as the agents that degrade the rock along much of the oceanfront surfaces and cause sediment to be produced. shoreline. Dune heights range from Hardbottoms are an important part of this 0 to approximately 15 feet. shoreface system, as they affect the

90 morphology of the shoreface and Non-Shoreface Geoindicators neighboring beaches (UNC, 2001). There are eleven different soil associations The Backside Shoreline Snows found within Carolina Beach, most of which have some type of development limitations. Due to its unique geological setting, the non-ocean shoreline of Carolina Beach fronts several different types of waterbodies. Myrtle Mitigation Recommendations West of Dow Road the town borders the Cape Fear River. Northeast of town is Snows Due to its geological formation, a significant Cut, an artificial waterway created to link portion of Carolina Beach is categorized as the Cape Fear River to Myrtle Sound. low to moderate risk. The town does, Myrtle Sound extends south from Carolina however, contain areas of high and extreme Beach Inlet to just north of Carl Winner risk. Figure CB 5 provides a detailed Street. FIGURE CB 4 illustration of risk and hazard geoindicators in Carolina Beach. Figure CB6 provides a Myrtle Sound is a shallow body of water, more generalized overview of risk. Areas of about 6 miles long and a few hundred feet to extreme risk, indicated in Figure CB6, about 1 mile wide, that lies between the extend several blocks westward from the mainland and the barrier beach adjacent to immediate open ocean shoreline. and north of Carolina Beach (Figure CB 4) (US Army, 1962). The shoreline of Myrtle Because of the ongoing beach nourishment 1966 to a maximum of 427 meters in 1985. project, shoreline migration is not Sound is characterized by an eroding marsh. The width of the inlet in 1999 was 202 considered a priority issue at this time. Even meters. Fluctuations in width are related to though the beach is artificially maintained, Inlet Geoindicators deflection of the ebb channel within the oceanfront properties and low areas are still throat of the inlet and the consequent Carolina Beach Inlet separates the barrier- subject to storm surge, flooding and storm erosion of the Masonboro Island shoulder. spit portion of Carolina Beach to the overwash. southwest from undeveloped Masonboro After the opening of the inlet, both Carolina Island to the northeast. The inlet connects While erosion problems associated with a Beach and Masonboro Island began to erode the Atlantic Ocean to Myrtle Sound and was migrating shoreline in Carolina Beach are at an increasing rate. The chronic erosion artificially opened by local interests in 1952 not addressed in this section, it does not along Carolina Beach was attributed to the at the site of Sugarloaf Inlet, a short-lived mean that erosion will not become an issue th reduced rate of sand bypassing at Carolina inlet of the late 19 century. once nourishment ceases, nor does it mean Beach Inlet as the ebb-tidal delta expanded that erosion should not be considered during and the system attempted to reach a balance The width of the inlet has varied widely over the development process. with local conditions (Cleary, 1999). the years from a minimum of 117 meters in

91 A priority hazard mitigation should consider the recommendation for Carolina Beach is to following parameters: establish more stringent community-wide geologic framework variables building restrictions in the event that the controlling individual island federal beach nourishment project is ever formation and evolution; discontinued. With development regional wave and storm restrictions in place, the town can climate; cumulative significantly reduce the amount of environmental consequences development that may eventually become of sand mining and beach vulnerable to coastal storm processes. nourishment; and the specific response of each Even though the open ocean beach in segment of the community Carolina Beach is artificially maintained, to sea-level rise. development immediately adjacent to the shoreline remains at extreme risk from a Implementing actions: major hurricane as well as from extra tropical cyclonic activity. • Require dune crosswalks for all new oceanfront

FIGURE CB 5 development. Protect the integrity of the ocean • The Town should give high beach and dune system and priority to the preservation of recognize the natural processes dunes, vegetation and and dynamics of the shoreline. topography as an important hazard mitigation The Town should strictly enforce state component. policy against sea walls, jetties, groins and • other artificial devices designed to stabilize Require any proposed the ocean shoreline. Sandbags should only development or be allowed as temporary protection devices redevelopment to rebuild (no more than two years) for imminently and revegetate dunes for the purpose of creating and threatened structures until they can be maintaining a continuous removed or demolished. dune line along the

oceanfront. In addition to basic economic considerations, decisions concerning the • Consider annually, through use of potential sand resources for long- the Capital Improvements term beach management in Carolina Beach Program process, providing funds for the acquisition of

92 open space in high hazard areas along the measures to reduce or prevent flood damage • Develop a long-range program to place existing ocean shoreline. from occurring in the first place. overhead utilities underground. Reduce the risks and vulnerability of • The Town should develop and implement a • Develop a visual enhancement program comprehensive Floodplain Management Plan (landscaping, buffering, landscaped corridors) to structures to damage and loss from and annually evaluate progress toward protect and enhance the natural vegetation and hurricanes and coastal storms in implementing the plan. topographical features of the Town. advance of such events. • The Town should continue to encourage • Inventory open space, actively pursue grants The Town should actively endorse relocation of structures that are threatened by and funding opportunities and develop and relocation, demolition and acquisition as the erosion and Town Staff should actively work with implement a plan to acquire and preserve open preferred alternatives for addressing the homeowners and Federal Emergency space throughout the Town. Management Agency to facilitate their impacts of barrier island migration and • Consider an incentive program to reward relocation. ocean erosion upon existing structures. developers that set aside additional open space Implementing actions: • Investigate the possibility of developing a long- in perpetuity term retreat/relocation/evacuation plan for all • The Town should sponsor studies to determine oceanfront structures in the event that beach Investigate more stringent building the optimal approach for removing threatened nourishment is discontinued codes for high hazard areas. structures from the oceanfront shoreline. • Prevent development densities from increasing Implementing actions: • The Town should investigate innovative Develop a set of regulations, programs and seek funds for mitigation • The Town should investigate the feasibility of measures such as relocation of threatened guidelines, and development review becoming a FEMA “Project Impact” community. structures from extreme hazard areas. processes that will help preserve • The Town should consider the applicability of • The Town should acquire oceanfront property topography, vegetation and other requiring “V Zone” structural certification for all when the opportunity arises. natural characteristics. structures. • The Town should investigate mitigation programs and grants to assist property owner in General Implementing Actions: Protect the physical and visual the relocation of threatened structures. integrity of the shoreline. • • The Town should take a more proactive Allow sand, deposited by storm surge and storm Implementing actions: approach towards the condemnation of overwash, to remain in place. damaged structures and issue civil citations • Develop a comprehensive Corridor Vegetation • Actively pursue all sources of funding including a when necessary. Enhancement Program. Capital Improvements Program to provide funds for open space and estuarine access projects. • Actively participate in the Federal Emergency • Institute a program of land acquisition to acquire Management Agency Community Rating land now to protect the visual integrity of the • Develop ordinances which would exclude System Program to develop mitigation Town. development detrimental to the estuarine environment.

93 Increase the amount of recreational • Develop an Open Space Plan designed to • The Town should develop regulations to require identify key locations for land and easement fuel tanks, including LP tanks to be adequately open space along the ocean and acquisition. anchored to prevent flotation or submersion in estuarine shorelines and increase the event of flooding. open space in other areas. Consider higher flood regulatory standards for vehicle and Implementing actions: equipment storage areas and

• Investigate the feasibility of implementing a structures that produce, use or facility fee schedule that will require payment of store volatile, flammable, explosive, fees from new development that will be used for toxic and or reactive materials. the acquisition of land for ocean and estuarine access areas. Implementing actions: • Submitting grant applications for shoreline • access projects when the opportunities arise. Develop a program to identify businesses and material storage areas where significant amounts of toxic or hazardous products are stored that could be subject to flooding.

94 FIGURE CB 6

•

95 96 COMMUNITY CASE STUDY 5: OCEAN ISLE BEACH, NC

Community Overview has changed little since 1990 (OIB, 1997). Projected Development Trends An average of 57.4 new housing units/year As of 1997, only 50% of the town’s platted The town of Ocean Isle Beach was was constructed in OIB between 1990 and residential lots had been developed and incorporated in 1959 and is comprised of a 1997, and this rate is expected to continue several large tracts had not yet been 6-mile long southwest-northeast trending through 2007. The town’s 1996 assessed subdivided. Over the next ten years, large barrier island and a 1,300-acre property valuation was #388,828,494 (OIB, single-family residences (over 5,000 ft2) are extraterritorial area on the mainland in 1997). expected to be built east of Beaufort Street Brunswick County, NC (Figure OIB 1). which will yield 6 dwellings per acre. The barrier island encompasses Development west of Beaufort Street approximately 1,950 acres, of is anticipated to consist of medium which 920 are undevelopable density (8 units/acre) multi-family marsh, beaches and surface water residential units in planned unit (OIB, 1997). Ocean Isle Beach is developments (PUD). One proposed positioned 33.89 degrees north of PUD is expected to add 700 units on the equator and 78.43 degrees 85.5 acres of land over the next 25 west of the prime meridian. The years. Water and sewer services will predominant littoral current be provided to all new lots (OIB, along Ocean Isle Beach is from 1997). west to east (Stanczuk, 1975). Population The island is separated from the mainland by salt marsh and the The current permanent population of Intracoastal Waterway. Vehicular OIB (excluding the ETA) is access to the island is achieved via approximately 767 with a seasonal NC Highway 904 along a population of 22,000 (OIB, 2001). causeway and high-rise bridge . Shoreline Changes Development The shoreline of Ocean Isle Beach The predominant land use in was nourished seven times between Ocean Isle Beach consists of 1974 and 1984. In early 2001, the single-family houses. This pattern Ocean Isle Beach commenced a 3.25

97 mile-long beach nourishment project The Town of Ocean Isle Beach is paying its walkovers were damaged. After Floyd, every extending from Shallotte Blvd. west to a share of the project from a Beach Erosion oceanfront structure east of Goldsboro Street point near Duneside Drive. This project will and Renourishment Fund that was was located seaward of the first line of place approximately 1,952,600.00 yds3 of established in 1989. This fund consists of natural stable vegetation. In addition to sand on the beach at an estimated cost of contributions from a structural damages, First Street, between $8.2 million (Wrenn, 2001). accommodation tax fund and three cents of Winston-Salem Street and Durham Street, the town's property tax rate (OIB, 2001). was undermined and washed-out. The project design profile, which will be maintained over the 50-year life of the Geology/Morphology Hurricanes Hazel in 1954, Hugo in 1989 project, calls for the beach to be increased in and Fran in 1996 also had significant width by approximately 125 feet in areas The Pamlico formation is a low, nearly level impacts on Ocean Isle Beach. Hazel that have a full construction profile. The terrace at an elevation less than 25 feet above completely overwashed Ocean Isle Beach, construction profile on both ends of the present sea level. The materials in this destroying 33 of 35 homes and washing the project will be tapered back to the existing formation are fine sandy loams, clays, sands remaining 2 homes nearly a mile away. profile in the transition areas. Maintenance and some gravel. Deposits of recent age Hurricane Hugo, despite making landfall fill, which will add an additional 50 feet of overlie the Pamlico formation. These include almost 200 miles south of Ocean Isle Beach, width to the beach, will be used to tidal marsh, beach sands and dunes. In destroyed several homes. Fran stranded compensate for the loss of fill material into marsh areas, the soil consists largely of many homes out in the surf zone (Pilkey, the near shore area, as well as through accumulations of peaty matter. The 1996). erosion, until the next maintenance thickness of the deposits varies from 15 to renourishment. After the initial 25 feet. Hazard Geoindicators construction, the beach is scheduled for periodic renourishment every 3 years for the Hazardous Events/Processes As previously discussed, hazard geoindicators 50-year life of the project. are local geomorphologic features that can, Ocean Isle Beach is subject to hurricanes, and do, influence coastal processes. The Sand is being dredged from the Shallotte tropical storms and extratropical cyclones. The hazardous processes of interest in Ocean primary hazard geoindicators found in Inlet channel borrow site on the east end of Ocean Isle Beach include: Isle Beach are storm surge, storm overwash, the island. Sand is being pumped onto the beach where bulldozers form the desired erosion and inlet migration. beach profile. Topographic Geoindicators In 1999, Hurricane Floyd caused significant Elevation The total cost over the 50-year life of the impacts to Ocean Isle Beach. East of renourishment project is estimated to be Greensboro Street, the first line of natural The average elevation of Ocean Isle Beach is $45.9 million. Project costs are shared stable vegetation (the building setback between six and eight feet above sea level. between federal, state and local sources. The reference feature) was displaced landward up Because of its low elevation, almost all of federal share is 65% and the non-federal to 70 feet in many locations. East of Ocean Isle Beach is located within the 100- share is 35%. Non-federal funding is cost Goldsboro Street, several structures sustained year flood zone (Figure OIB 2). shared between the state and local sponsors. structural damage and virtually all wooden

98 V-zone Base Flood Elevation ranges from 15 storm surge height, storm wave height, wave existing reference feature (i.e. frontal dune to 23 feet while the AE-zone Base Flood energy and storm surge ebb flow. toe, first line of stable vegetation or Elevation ranges from 13 to 17 feet. NFIP structure). Immediately after Hurricane V-zone areas include land bordering The Ocean Beach Floyd, the width of the dry beach from Shallotte and Tubb’s Inlets, along the The average, long-term erosion rate in Greensboro Street east to Shallotte Inlet oceanfront and immediate backside of the Ocean Isle Beach is approximately 2 measured less than 20 feet (Coburn, 1999). island. AE-zones include much of the land feet/year except along the eastern-most end The dry beach, immediately post between the primary dune crest and the where erosion rates are listed at 5 feet/year nourishment, is expected to average 125 feet backside of the island. (NC DCM, 1992). The ocean beach in in width. Ocean Isle Beach has been, and currently is Vegetation being, artificially maintained through a Primary/Frontal Dunes Along the back edge of the island is a broad federal beach nourishment project. Prior to Hurricane Floyd, Ocean Isle Beach area of maritime forest/shrub thicket that was fronted by a heterogeneous mix of dune extends from Second Street to the eastern Prior to nourishment, the dry subaerial types. East of Southport Street, the frontal end of the island. Vegetation native to beach ranged in width from 0 to 50 feet, dune line consisted primarily of bulldozed, Ocean Isle Beach includes Spartina patens measured from the high water line to an unvegetated, scarped sand piles. Exposed (cord grass), Ammophila breviligulata sandbags were observed in several (American beach grass), Uniola locations between Raleigh and paniculata (sea oats), Baccharis Highpoint Streets. A 140-foot long halimifolia (eea myrtle), Myrica vegetated frontal dune was located cerifera (wax myrtle), Iva frutescens immediately in front of the Winds (marsh elder), Quercus virginiana Oceanfront Inn at 310 East First Street. (live oak), Juniperus virginiana (red At this location, sandbags had been cedar), Slex vomitoria (yaupon) and covered with sand and dune vegetation Spartina alterniflora (smooth cord had been established. As a result, grass). additional sand had been trapped and dunes had built up. Shoreline Geoindicators West of Southport Street to the pier, the Shoreline geoindicators include frontal dunes were scarped but well- geomorphologic features of the ocean FIGURE OIB 2 vegetated with little signs of bulldozing. beach, the estuarine shoreline and the Frontal dune heights averaged 8-10 feet. offshore continental shelf. This category of geoindicators influences

99 West of the pier, the frontal dune averaged just under 10 feet in height, was well- vegetated and showed little signs of erosion. FIGURE OIB 3 Bathymetry Ocean Isle Beach fronts Long Bay, the shelf Ocean Isle embayment from south of Cape Fear to Bh Cape Romain, South Carolina. Long Bay is sediment starved and dominated by outcropping Cretaceous and Tertiary units (Cleary, 2001). The bathymetry off Ocean Isle Beach is illustrated in Figure OIB 3. Ocean Isle Beach is classified as mesotidal which means it has a moderate tidal range. Wave energy is also moderate.

The Estuarine/Backside Shoreline The soundside shoreline of Ocean Isle Beach is largely characterized by an eroding salt marsh and finger canals that were dredged to provide access to Tubbs and Shallotte Inlets. Coastal wetlands, as defined by the NC Coastal Area Management Act, are generally located in the northern portions of the island adjacent to the Intracoastal Waterway. The most substantial area of wetlands is located in the northwest portion of the island between the Intracoastal Waterway and Old Sound Creek. Another wetlands area is the land adjacent to the finger canals leading to the waterway (OIB, 1997).

Inlet Geoindicators Ocean Isle Beach has two inlet hazard areas: Tubbs Inlet to the west and Shallotte Inlet to

100 the East. Tubbs Inlet is an unstable inlet that In 1994, the central dune ridge of the island state participates by action of the has demonstrated erratic movements in the was largely removed by bulldozing just west department. According to 15A NCAC 02G past and may do so in the future. Prior to of Highway 904. The ridge was the only .0107: 1970, Tubbs Inlet was migrating to the west. portion of the island above the 100-year Before the start of project construction, the sponsoring During this period of time, the primary flood level. local government(s) will establish land-use controls to conserve protective dunes and to insure that the damage feeder channel behind the Ocean Isle potential is not significantly increased by further shoulder of Tubbs Inlet was infilled, and it Mitigation Recommendations development. Such land use controls must meet or no longer was the primary feeder channel. exceed all requirements of the state guidelines for Areas of Environmental Concern (15A NCAC 7H) and be Prior to the 2001 beach nourishment consistent with the approved local land use plan prepared At some time between 1970 and 1983, Jenks project, the eastern third of Ocean Isle Beach under the provisions of the state guidelines for Land Use Planning (15A NCAC 7B). Creek was dredged, opening it to the had been experiencing extensive erosion. Intracoastal Waterway. The dredging and Because of the ongoing federal beach With the required development restrictions opening of Jenks Creek allowed a greater nourishment project, shoreline migration on volume of water to be exchanged in place, Ocean Isle Beach can be certain Ocean Isle Beach is not currently considered that additional development will not between the ocean and estuary. This a priority issue. However, even though the infilling, or the reduction in the primary eventually become vulnerable to coastal beach is being artificially maintained, storm processes when the federal beach eastern feeder channel along with the oceanfront properties and low areas are still dredging of Jenks Creek on the western side nourishment project ends. subject to storm surge, flooding and storm of the inlet, is likely to be among the variable overwash. factors causing the present easterly migration However, even though the open ocean beach in Ocean Isle Beach is artificially of Tubbs Inlet (Clearly, 1996). While erosion problems associated with a maintained, development immediately migrating shoreline in Ocean Isle Beach are adjacent to the shoreline remains at extreme Non-Shoreface Geoindicators not addressed in this section, it does not risk from a major hurricane as well as from mean that erosion may not become an issue, extra tropical cyclonic activity. Four soil types are found within Ocean Isle nor does it mean that erosion should not be Beach: Bohicket, Carteret, Corolla and considered during the development process. Newhan. Bohicket and Carteret soils drain very poorly and are subject to severe flooding Protect the integrity of the ocean In light of the ongoing federal nourishment beach and dune system and and ponding of water. These soils are found project, the priority hazard mitigation primarily in the marshes and tidal flats. recommendation for Ocean Isle Beach is to recognize the natural processes and Corolla and Newhan soils are found mainly establish and enforce stringent community- dynamics of the shoreline. along the oceanfront Corolla is prone to wide building restrictions that prevent any flooding and ponding of water while increase in development. This is, in fact, a OIB should strictly enforce state policy Newhan has severe limitations for septic NC state requirement (15A NCAC 02G against sea walls, jetties, groins and other system use (OIB maintains a central sewer .0107 - Special Beach Erosion Control artificial devices designed to stabilize the system and does not permit septic systems Requirements) for all beach erosion control ocean shoreline. Sandbags should only be on the island). or hurricane protection projects in which the allowed as temporary protection devices (no more than two years) for imminently

101 threatened structures until they can be Reduce the risks and vulnerability of • OIB should actively participate in the Federal removed or demolished. Emergency Management Agency Community structures to damage and loss from Rating System Program to develop mitigation In addition to basic economic hurricanes and coastal storms in measures to reduce or prevent flood damage considerations, decisions concerning the use advance of such events. from occurring in the first place. of potential sand resources for long-term OIB should actively endorse relocation, • OIB should develop and implement a beach management in OIB, the town should comprehensive Floodplain Management Plan consider the following parameters: geologic demolition and acquisition as the preferred alternatives for addressing the impacts of and annually evaluate progress toward framework variables controlling individual implementing the plan. island formation and evolution; regional barrier island migration and ocean erosion wave and storm climate; cumulative upon existing structures. • OIB should Investigate the feasibility of environmental consequences of sand mining developing a long-term retreat/ relocation/ and beach nourishment; and the specific Implementing actions: evacuation plan for all oceanfront structures in response of each segment of the community the event that beach nourishment is • to sea-level rise. OIB should sponsor studies to determine the discontinued optimal approach for removing threatened Develop a set of regulations, Implementing actions: structures from the oceanfront shoreline. guidelines, and development review • OIB should investigate innovative programs and • Require dune crosswalks for all oceanfront seek funds for mitigation measures such as processes that will help preserve development. relocation of threatened structures from extreme topography, vegetation and other hazard areas. • The Town should give high priority to the natural characteristics. preservation of dunes, native vegetation and • OIB should encourage relocation of structures General Implementing Actions: topography as an important hazard mitigation that are threatened by erosion and Town Staff component. should actively work with homeowners and • OIB should allow sand, deposited by storm Federal Emergency Management Agency to • Require any proposed development or surge and overwash, to remain in place. facilitate their relocation. redevelopment to rebuild and revegetate dunes • OIB should develop a comprehensive Corridor for the purpose of creating and maintaining a • OIB should acquire oceanfront property when Vegetation Enhancement Program. continuous dune line along the oceanfront. the opportunity arises. • OIB should institute a program of land • Consider annually, through the town's Capital • OIB should investigate mitigation programs and acquisition to acquire land now to protect the Improvements Program process, providing grants to assist property owner in the relocation visual integrity of the Town. funds for the acquisition of open space in high of threatened structures. • and extreme hazard areas along the ocean OIB should develop a visual enhancement • OIB should take a more proactive approach shoreline. program (landscaping, buffering, landscaped towards the condemnation of damaged corridors) to protect and enhance the natural structures and issue civil citations when vegetation and topographical features of the necessary. Town.

102 • OIB should inventory open space, • Develop ordinances that would actively pursue grants and funding exclude development detrimental to opportunities and develop and FIGURE OIB the estuarine environment. implement a plan to acquire and preserve open space throughout the Town. Increase the amount of • OIB should consider an incentive recreational open space program to reward developers that along the ocean and set aside additional open space in estuarine shorelines and perpetuity increase open space in

other areas. Investigate more stringent Implementing actions: building codes for high hazard areas. • OIB should investigate the feasibility of implementing a facility fee Implementing actions: schedule that will require payment of fees from new development that • OIB should investigate the feasibility will be used for the acquisition of of becoming a FEMA “Project land for ocean and estuarine Impact” community. access areas. • OIB should consider the applicability • OIB should submit grant of requiring “V Zone” structural applications for shoreline access certification for all structures located projects when the opportunities in the 100-year NFIP flood zone. arise. Protect the physical and • OIB should develop an Open visual integrity of the Space Plan designed to identify key locations for land and easement estuarine shoreline. acquisition. Implementing actions:

• Actively pursue all sources of funding including a Capital Improvements Program to provide funds for open space and estuarine access projects.

103 Consider higher flood regulatory Implementing actions: • OIB should develop regulations to require fuel tanks, including LP tanks to be adequately standards for vehicle and • OIB should develop a program to identify anchored to prevent flotation or submersion in equipment storage areas and businesses and material storage areas where the event of flooding. structures that produce, use or significant amounts of toxic or hazardous store volatile, flammable, explosive, products are stored that could be subject to flooding. toxic and or reactive materials.

104 REFERENCES

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106 Stanczuk, D.T., 1975. Effects of development on barrier island evolution, Bogue Banks, North Carolina. Unpublished Master's Thesis, Duke University, Department of Geology, Durham, North Carolina, 126 p Texas General Land Office; Dune Protection and Improvement Manual for the Texas Gulf Coast; http://www.glo.state.tx.us/coastal/dunemanual/walkovers.html; 2001 United States Army Corps of Engineers; http://cirp.wes.army.mil/cirp/structdb/structdb.php3?id='181' 2001 United States Census; http://quickfacts.census.gov/qfd/states/37000.html; 2001 University of North Carolina Wilmington; Center for Marine Science; http://www.uncwil.edu/cmsr/, 2001 US Army; Carolina Beach and Vicinity, North Carolina; Washington, DC: May 1962 USGS, Sidescan-Sonar Imagery of the Shoreface and Inner Continental Shelf; U.S. Geological Survey Open-file Report OF 98-616; Wood Hole, MA, 1998 Wrenn, Lee; Ocean Isle Beach Renourishment Project Home Page; http://www.seashell.com/oibhome.htm; 2001

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