Learn about coastal hazards

Chapter 5: Evolving Approaches to Property Damage Mitigation:
Focusing on the Island Front through Engineering and Regulation

*The human perspective of coastal hazards tends to be biased; focused on the sea and the shoreline. The erosive waves roll into the front of the island. The furious storm approaches from offshore with winds and storm surge, as does the tidal wave. Shoreline erosion is marked by scarped dunes, toppled trees, decks and houses collapsed on the back of the beach, and streets that suddenly end in the space above the beach. To prevent or reduce such damage, the various mitigation schemes and techniques that evolved tended to concentrate on the shoreline (fig. 5.1). This shoreline focus was also driven by the early development patterns that concentrated buildings on the ocean front, and the fact that coastal protection was the charge of a specific governmental agency, the U. S. Army Corps of Engineers. If the history of property-damage mitigation were an adventure film, the story line would go something like the following:
o Shoreville is built on the shoreline.
o Shoreville gets in trouble (storms/erosion).
o Rescue---shoreline engineering (hold that line).
o Shoreville's beaches disappear---more trouble.
o Rescue---setbacks and zoning (keep em' off the line).
o Time passes and the shoreline catches up to the setback.
o Rescue---the new (old) engineering: beach nourishment.
o More beach erosion, more property damage, more financial loss.
o Shoreville continues searching for a solution.

*The question is "can there be a happy ending for Shoreville?". The answer depends on how the town continues to respond to the natural hazards. We will evaluate and discuss several "Shorevilles" and their various approaches to coastal zone management in this chapter and in Chapters 6, 7, and 9. Good, bad, right, or wrong, each example gives insight to "Living by the Rules of the Sea!"

*Our society has learned much in the past several decades about coastal processes and about the natural changes that occur on beaches and coasts. Our attention was drawn first to the beach where we observed that retreating shorelines may undermine houses, destroy dunes, or bring the surf zone closer to the buildings, increasing the storm damage potential. Traditional coastal property damage mitigation techniques have basically fallen into two broad categories: engineering and land-use planning (Godschalk et al., 1989). Engineering is used to alter the landscape and/or strengthen buildings. Such mitigation efforts have concentrated on the beach, either armoring the shoreline, replenishing the beach itself, or moving buildings back from the beach, largely neglecting the near beach interior areas. Land-use planning is used to control the locations of buildings and thereby reduce (or limit) the number of buildings and people at risk.

Victims of History?

*When America's first barrier-island resort communities developed, no grand plan was followed. The focus was on the recreational beach, sea bathing, and taking in the air. Hotels were constructed at the back of the beach and summer board walks laid down over the dunes to be taken up at the end of the season. As the crowds increased, so did the number of structures, including dance and amusement pavilions, and cottage communities. The boardwalks became fixed, and so did the communities. Elsewhere along the USA shore, barrier-island towns grew from a variety of beginnings including old plantation summer retreats, fishing camps, church camps, and hunting reserves; always driven by one common element---access. The way over the water from mainland to island may have been a 19th Century causeway, an early railroad bridge, or carriage bridge, but the access provided the initiative for growth. All of these communities shared one thing in common: none of them knew the nature of the islands on which they were located.

*In a matter of decades, most of these towns and local developments began to experience island migration; what they perceived as beach erosion. Thinking that it was just a small stretch of beach that was moving just a little bit; not realizing or understanding that the islands were actually responding to a rising sea level. The mindset of "defending" the shoreline or "reclaiming" the land prevailed. What started with a few logs or rocks to protect a single house, grew to small walls, then larger walls, revetments, and massive engineering works and beach replenishment projects. The experience also was perceived as a local problem, not of regional or global extent. As a result, the patterns of access and new development continued into the post-World War II era of affluence, mobility, and the continued fashionability of the seashore---each new community in turn impacted by storms, or the ultimate end of the day-to-day dynamics of the migrating barrier island.

The Great Age of Engineering

*Although settlements like Diamond City, NC and Edingsville Beach, SC threw in the towel and moved after devastating hurricanes in the 1890s, few communities even considered relocating as an option. The technology to move out of harm's way existed. In 1888 the large, wooden Brighton Beach Hotel on Coney Island, NY was moved back from the shoreline using steam locomotives (fig. 5.2). But relocation was not given its due in a time devoted to great engineering construction marvels. This was the era of the Brooklyn Bridge, the Eiffel Tower, the beginning of plans for the Panama Canal. In a time when no river was too wide to bridge, dam, or jetty; no isthmus too great to breach with a canal, the natural response to a disaster like the Galveston Hurricane of 1900, which left over 6000 dead, was to build a mighty protective wall against such future events (fig. 5.3). It was humans against the elements, and no one doubted that humans could out engineer the forces of nature.

*The Rivers and Harbors Act of 1889 charged the U. S. Army Corps of Engineers (ACOE) with maintaining navigable waterways. Maintaining inlet and river mouth entrances to harbors was achieved through the construction of great jetty systems (e.g., Nantucket Harbor, MA; Charleston Harbor, SC; Savannah Harbor, GA; Fernandina and Jacksonville Harbors, FL). Developed ocean shorelines were also the shores of navigable waters, so it follows that the Corps would combat erosion on the fronts of developed islands using the arsenal of engineering (solid structures) to defend against nature. Coastal engineering, the building of sea walls and groins, became the pattern for property-damage mitigation. These structures shared one thing in common: directly or indirectly they contributed to the loss of the beach which fronted the structure (the raison d'être for most coastal communities).

*The coming of the automobile and post-World War II affluence spurred on barrier island development, but our understanding of island dynamics had not yet come of age. Hurricanes and erosive storms likewise continued, as did the archaic engineering "solutions". Seawalls and groin fields remained as the common option available to communities in trouble due to shoreline retreat, storm-surge flooding, and frequent overwash. The seawalls that were growing larger with time may have given a false sense of security with respect to the protection (or lack there of) afforded against hurricanes and northeasters. In many communities, cottages were replaced by larger housing units (i.e., duplexes, "seacabins," condominiums, high-rise complexes).

The Sea Bright, NJ Example

*Sea Bright, New Jersey, has been suggested as the end result of following the philosophy of hard stabilization. Pilkey and Wright (1988) analyzed historic photographs and sketches to reconstruct the sequence of shoreline engineering and changes that took place in the Sea Bright area. Their work indicates that the area was an undeveloped spit (barrier sand bar attached to the mainland) into the 19th century. By 1868 the settlement of Nauvoo, a cluster of fishermen shacks and sheds, was spread over the low ground behind the natural, unstabilized beach which was steep and narrow.

*The first "permanent" house was built in 1869 at the north end of the development, and by 1877 the shoreline was lined with a row of houses at the back of the beach. These buildings were positioned near the high-tide line with little or no dune protection. Almost immediately they were in trouble, and by 1886 protective walls had been built in front of some of the houses (fig. 5.4). A postcard dated 1903 shows a large rubble wall lining the beach at the north end. This may be the rubble mound wall installed in 1898 (Kraus et al., 1988). In 1931 the rubble mound wall was similar to the present wall in terms of dimensions, but a recreational beach remained in front of the wall. The remains of this beach are held in place today by the long groins in front of the 3-4 block stretch of "downtown" Sea Bright. But in either direction of the groins virtually no beach remains in front of the sea wall (fig. 5.5).

*The original first row of houses also is gone and today the high seawall (17 ft crest elevation) blocks the view of the sea. The massive wall "protects" an area of less than one square mile, and a population of less than 2000 year-round residents. In 1984 a northeaster, possibly a 30-year storm, caused $82-million in damages, primarily to the seawall and beaches. This amount was essentially equal to the value of all of the buildings in town. What would the cost be in a really big storm?

*Sea Bright truly is at an end point. Maintaining the wall is more costly than the value of the property it is supposed to protect (the wall potentially can trap flood waters and contribute to property damage). The beach, robbed of its local sand supply by the seawall and probably impacted by redistributed wave energy off of the wall, has all but disappeared. The community does not have the financial resources to maintain the wall and must go hat-in-hand to the taxpayers at the federal and state level for coastal "welfare". A more prudent management alternative would be the gradual removal and/or relocation of the buildings. In the short-term the community must look for ways to mitigate damages, other than reliance on the seawall.

The Shift from Engineering to Regulation

*Initially, armoring the shoreline to hold it in place and protect beach front buildings and property through engineering was the method of choice. Beach replenishment is a modern equivalent of the old engineering "fix" to hold the line. More recent methods have been through regulation, often loosely put into the category of land use planning. Land use planning and zoning efforts have taken a broader approach, and attempted to consider the entire island or coastal zone. To look at the high density of development along much of our shores, it's easy to see that land-use planning either hasn't worked or is a "johnny-come-lately" to the arena of coastal-zone management. Table 5.1 is a list of options that have been utilized by communities and individuals to reduce the potential for coastal property damage (fig. 5.1). Examples include stricter building requirements for buildings in flood zones, especially velocity zones where the flood level is topped by waves (i.e., the island front), and set-back requirements for houses built on the eroding fronts of islands. Hazard-sensitive zoning requirements also often focus on the front sides of islands.

*By the 1950s and 1960s the realization that coastal buildings were subjected to higher winds and flooding (even those behind seawalls) led many states and communities to adopt more stringent building codes to strengthen buildings in the coastal zone. By the 1970s the national experience dictated that something be done to control the losses incurred from hurricanes and great storms like the Ash Wednesday Storm of 1962. The tremendous loss of habitat (salt marshes, shell fisheries) also was being recognized as fisheries were forever lost or closed down due to pollution. The results were two-fold: the National Flood Insurance Act of 1968 (also the result of the tremendous loss of property on riverine floodplains), and the Coastal Zone Management Act of 1972. Building requirements were upgraded, and many coastal states began to define critical environments and control development through permit processes. Communities and states adopted approaches such as zoning and set-back requirements.

*Land-use planning control is, in truth, a before-the-fact approach. In other words, it provides guidelines that are easy to incorporate into newly developing areas, but difficult in already developed (that is, most) coastal areas. An example is the requirement that all new structures be built a minimum distance back from the shore. Such setback regulations, however, are only interim or temporary "solutions" to the erosion problem. Setback laws require buildings to be positioned a defined "safe" distance from the shoreline; this distance usually being determined by the natural rate of erosion. In North Carolina, for example, oceanfront single family houses must be set back 30 times the average annual erosion rate while larger structures such as hotels and condominiums must be set back 60 times the average annual erosion rate. The average annual erosion rate is determined from aerial photograph analysis of historical shoreline changes by a consultant to the North Carolina Division of Coastal Management. Choice of the magic number 30 has much to do with the life of a mortgage, and little relationship to long-term survival of property. Thus, setbacks help protect the banker, but not the second generation of owners. Setback laws vary by state and community, and may change in time. Check with your state or local coastal management office or town hall to find out your situation.

*Zoning and land use planning in the coastal zone and related issues are covered well in various studies. See, for example, Godschalk et al. (1989), Beatly et al. (1994), as well as several additional sources listed in Appendix B. Although moving in the right direction, the regulatory approach has not stopped the rising cost of storm damage or the concentration of larger populations and their developments in these hazardous zones. Given the likelihood that everyone living on barrier islands are not going to get up and move to higher ground, society must look for ways to defuse the bomb.

Next Step in Property Damage Mitigation: PAR for the Course

*In order to reduce the potential impact of coastal processes a more holistic approach to mitigation is needed. Society must move from engineering against nature to working with nature; from a focus on site-specific and linear (island front) regulation to a whole-island perspective; and from shore hardening/hold-the-line programs to approaches which concentrate on Preservation-Augmentation-Repair (PAR) of the natural systems that we occupy with our development.

*Coastal processes involve the broader "coastal zone", not just the beach and shoreline. Mitigation plans must take a whole-island point of view, including the nature of the coastal zone of the adjacent mainland. This view implies considering "nontraditional" mitigation approaches which give attention to island interiors and lagoonal shorelines as well as the ocean beach and inlet shores. Coastal and island dynamics must be more completely incorporated in order to delineate existing and potential inlet hazard zones (See Chapter 7), and to identify problem areas that may be evolving over the coming decades (e.g., loss of forest cover; destabilization or loss of dune fields). And just as these inner island areas must be given attention, the offshore, submerged island platform must be managed as part of the total system (e.g., tidal deltas and shoals may provide important protection from waves and provide a natural sand supply, so that their loss will have serious repercussions for the island system). As communities become more desperate for sand supplies, all eyes are turning seaward. The removal of offshore sand bodies will create a new set of problems for island property.

*Nevertheless, the front side of barrier islands is a good place to begin a consideration of property-damage mitigation.


Hard Stabilization: Hold that line

*Hard shoreline stabilization generally involves structures that either block and dissipate wave energy or that trap sand to widen a beach. A wide variety of types and designs of hard stabilization exists, but there are basically three major categories: (1) shore-parallel structures on land such as seawalls (2) shore-parallel structures offshore such as breakwaters, and (3) shore-perpendicular structures such as groins and jetties. Hard stabilization has been a very common shoreline management tool through the centuries, even before Roman times. In the USA, many of the disadvantages associated with hard stabilization are only now understood after more than a century of use.

*Shore-Parallel Structures on Land.--Seawalls and their cousins are shoreline engineering structures that are built parallel to the beach on the subaerial beach. These structures are the most common type of hard stabilization.

*Seawalls are wood, steel, rock, or concrete structures designed to protect the upland from the impact of waves (fig. 5.7). Commonly, especially along the southern and mid-Atlantic U.S. shoreline, seawalls are built at low elevation, and are not intended to block storm waves especially if accompanied by a storm surge. Such walls instead function mainly to halt the retreat of the shoreline into the line of buildings. Overtopping of seawalls is common in hurricanes and walls fail for a variety of reasons including building up of water pressure (from storm surge) on the landward side, storm-surge ebb flow tearing the wall apart, scouring and undermining by waves and storm-surge ebb, and direct wave attack. Seawalls should extend vertically well down into the beach to prevent undermining.

*Bulkheads are generally indistinguishable from seawalls to the general public. In theory, the primary purpose of bulkheads is to hold back the land from slumping or eroding into the sea and not to absorb wave energy (fig. 5.6). In reality, bulkheads serve both purposes and usually the term refers to small, low seawalls.

*Sandbags are often used as a temporary erosion measure, but such walls rarely have a foundation, so they are swept away or moved about by the first storm (fig. 5.10). Bags, whether filled with sand or concrete, are best viewed as temporary protection, buying time before moving a building back.

*Gabions also are used to construct seawalls or revetments. This type of structure consists of rock-filled rectangular steel wire mesh cages piled one on another to form a wall (fig. 5.11). Although the wire is plastic coated, the mesh inevitably corrodes, the gabion ruptures, the rocks spill out, and the wall disappears! Jagged wire and the rock leakage are strewn over the beach to form a hazard to beach strollers.

*Properly designed, hard shoreline structures are dependable methods of halting shoreline retreat and protecting coastal property. Their disadvantages, however, are many, and are not solely aesthetic. Hard shoreline stabilization leads to degradation of the recreational beach, is costly both in the short term and long term, destroy beach aesthetics, makes beach access difficult, and is dangerous (Table 5.2).

*Seawalls lead to narrowing of recreational beaches by means referred to as active, passive, and placement beach loss. Passive beach loss occurs in a landward retreating shoreline situation, where a seawall (or highway, or building) acts as a fixed reference point. As the shoreline continues to erode or retreat landward, the beach must narrow and eventually disappear. This process often takes several decades to complete. Active beach loss occurs when the seawall reflects wave energy or in other ways intensifies the surf-zone processes leading to beach sand loss. Little is understood about this mechanism as yet because of the difficulty in measuring and observing wave/current processes when most of the "action" takes place during storms. Placement beach loss occurs when a seawall is built seaward of the dunes and part of the beach is claimed by the seawall (figs. 5.12 and 5.13). That is, what used to be part of the recreational beach is now behind the seawall. Such placement of seawalls has led to beach loss in many locations, perhaps the most famous of which was Miami Beach prior to its 1981 replenishment.

*All types of seawalls are subject to numerous hydraulic forces that must be accounted for in wall design and construction materials. Walls intended to prevent wave attack on buildings must be constructed high enough to prevent storm wave overtopping, but they also must be implanted deep enough in the beach to prevent undercutting. In general, the maximum depth of expected scour is roughly equal to the highest breaking wave at the site. Thus, maximum storm waves of 1 meter require a footing depth of at least 1 meter. Some scour will still occur, and placing large rocks at the foot of the structure will help reduce this effect, but will also further reduce the recreational value of the beach.

*A seawall or bulkhead protects only the land and buildings behind it. The ends should be joined to neighboring structures if possible. Where none exist, wing walls or tie-ins to the adjacent land must be built to prevent wave flanking by wave erosion at the ends of the wall. Wing walls are only a temporary measure because erosion will continue and extend beyond each successive flank built to "solve" the problem.

*Additional strength can be gained through the use of tie-backs (figs. 5.6 and 5.12). Tie-backs anchor the upper part of the wall with steel cables or rods to logs or other anchors (called deadmen) deeply embedded into the beach or bluff. Accumulating water and soil pressure will build behind bulkheads and seawalls. Drainage must be provided to allow water to escape from the landward side of the wall without carrying the backfill material with it. Backfilling with gravel and having frequent openings (weep holes) along the lower part of the wall allow water to escape. Walls should be backed by filter cloth.

*This brief discussion of seawalls is not intended to give design advice, but rather to illustrate some of the considerations of construction, and indicate why these walls fail. A professional engineer should be consulted prior to any construction. Seawalls and other types of shoreline engineering structures require maintenance. Remember to ask the engineer how much maintenance will cost, how long they "guarantee" the design, how the wall will perform under typical storm conditions (to be expected during the wall's design life), and what the impact of the wall will be on the adjacent property and beaches?

*Environmental Impact of Seawalls.--A seawall doesn't absorb all of a wave's energy--some of that energy moves off the wall by reflection, scouring and eroding sediment in front of the wall. Some of the energy is also deflected along the wall to the adjacent unprotected property where the energy is spent eroding the shore. In addition, the narrowed beaches in front of seawalls lead to a reduced sand supply to adjacent beaches, further exacerbating erosion of neighboring beaches. Where wall-protected areas form mini-headlands, the waves may be refracted by the wall into the adjacent unwalled shore; again concentrating erosive wave energy. Stroll along the shore of a hotel or condominium row almost anywhere and observe where the beach is narrow or missing--the offending walls, bulkheads, or revetments will be obvious. The name of the community is of no consequence, the effects of seawalls are the same.

*Unwise building location--major structure.--America's shoreline is dotted with examples of buildings initially located too close to the shore. Folly Beach, SC provides a convenient example. Folly Island is developed along its entire length and width, with the exception of its extreme ends. The northern end is a U. S. Coast Guard facility, the southern end is a county park. Wood frame, single-family beach cottages and several small commercial buildings comprise the majority of the island's development. The dominant structure on the island is the Holiday Inn located at the end of SC Route 171. The Inn was built in 1985 on the site of the old Folly Beach Pavilion, a popular gathering place since before World War II. The Folly Beach pavilion/pier was opened in the 1920's and burned in 1957. It was rebuilt in 1960, but burned again in 1977 and was rebuilt in 1995. When it was first opened, the pavilion had a wide healthy beach in front of it. By the time it burned the second time, the high tide recreational beach was gone.

*As mentioned, the Holiday Inn was built in a very dangerous position, essentially out on the beach (although elevated)! The recreational beach would not exist, not even at very low tide, if the beach front were not frequently nourished. This island is in such an erosive state that even though a replenished beach was emplaced in the spring of 1993, there was no high-tide beach by spring of 1994, even without a major winter storm! Locating this building on the shoreline was a mistake that should not have been allowed to happen, and would have been easy to avoid.

*Seawalls, Sediment Loss, and Narrowing Beaches.--The immovable object has another significant effect. Beaches often get part of their sediment from erosion of the land at the back of the beach. Walls cover up that source, starving the beach of its sediment supply, either in the area of the wall or downdrift of the wall. Such sediment starvation is a particular problem in places along the New England shoreline where erosion of old glacial sediments is a major source of beach sands and gravels.

*If beaches are the attraction, and we build walls to protect property at the expense of the beaches' sand supply, then we kill the goose that laid the golden egg (fig. 5.14).

*Lengthening Walls and Narrowing Beaches.--Regional comparisons of dry beach (recreational beach) widths in front of seawalls to dry beach widths on beaches not altered by engineering structures indicate that beaches are consistently narrower in front of seawalls. In New Jersey the narrowest average dry beach widths are found in front of seawalls; the widest beaches were unstructured (Hall and Pilkey, 1991). This relationship is not unique to New Jersey, however. In a study comparing developed stabilized and unstabilized beaches along the east coast (Pilkey and Wright, 1988), dry beach width is consistently and significantly narrower in front of seawalls. That same study showed that stabilized beaches in the San Juan, Puerto Rico metropolitan area averaged only about 3-7 feet (1-2 meters) in width, while unstabilized beaches along the same stretch averaged over 18 meters wide.

*Offshore Breakwaters.--Breakwaters are offshore structures, usually shore-parallel, specifically designed to reduce wave energy and shelter a portion of the shoreline. The effect of breaking wave energy is to interrupt or lessen longshore transport of sand, causing accumulation of sand behind the structure (figs. 5.15 and 5.16). As the local beach widens, this starves downdrift beaches of sand, similar to the effects of groins and jetties discussed below. In the 1980s and 1990s breakwaters again became "fashionable" with proponents of shore hardening, and new breakwater systems consisting of portable concrete segments were installed in Florida and New Jersey. Although it is necessary to observe shoreline structures on a decadal time frame to understand their impact, early reports indicate these "portable" breakwaters are not succeeding as claimed by their "inventors." At the same time warnings were being raised about the ill effects of these new structures, Palm Beach, FL was reversing the trend. The Palm Beach breakwater built in the early 1990s was scheduled to be removed by summer 1995. The device created more erosion problems than it solved, including the area in back of the breakwater.

*Shore-Perpendicular Structures.--Whereas shore-parallel structures are built basically to block wave energy, shore-perpendicular structures are designed to block the alongshore flow of sand. The trapped sand, in theory, is held as a beach deposit.

*Groins.--Groins are walls, built perpendicular to the shoreline, designed to trap and hold sediment flowing in the longshore current, thus, rebuilding an eroding beach (fig. 5.17). Made of rock, wood, concrete, or steel, groins are also useful in retention of sediment already on the beach or retaining new sand from a nourishment project. Groins are often, but not always, used in conjunction with seawalls and sometimes with beach replenishment. Groins can be low or high, long or short, depending on the desired extent of sand trapping. Spacing of groins in a "groin field" depends on local sand supply and wave characteristics and is highly variable from one beach to another.

*Environmental Impact of Groins.--The problem with groins is that they trap sediment on one side and intensify erosion on the other, depending on the net littoral drift direction. Updrift beaches are widened, downdrift beaches are "starved" of sediment. Many lawsuits have been initiated by property owners claiming increased erosion damage as a result of nearby groin construction.
Groins should not be used where there is a low or no supply of sand flowing laterally along the beach. When no sand builds up, the groins are not doing their job. After a long period of time, or very quickly during a storm, the shoreline can retreat past the landward end of groins causing them to become detached from the shoreline. Once detached, water and sediment pass between the groins and the beach, rendering the groins useless (fig. 5.18).

*The bottom line on a world-wide basis, according to some engineers and geologists, is that groins are a losing proposition for beaches. Sand buildup temporarily gained in one place simply transfers the erosion problem to another place and worsens the overall erosion problem.

*Jetties are analogous to groins, but constructed specifically to "stabilize" navigational inlets and entrances. The structures are intended to make navigation safer and channel maintenance cheaper. Jetties cause more extreme downdrift erosion than groins because they more completely interrupt the longshore sediment transport system. The great number of jetties along America's shores, particularly the Atlantic and Gulf Coasts, suggests a widespread and significant frequency of associated erosion problems. Along the east coast of Florida, jetties may be the principal cause of shoreline retreat. Jetties that extend far out to sea may also channel sand offshore during storms causing a permanent loss of the sand supply in the longshore drift. Newer jetty designs call for sand bypassing systems to the sand in the longshore drift. Bypassing systems, however, can not operate during storms, the time when much of nature's transport work is being accomplished. Jetties are the antithesis of sand conservation in an island system.

*The Charleston Harbor Jetties.--Jetties are necessary to provide safe harbor entrances, but they protrude so far out into the nearshore sediment transport system that they can essentially block all the sediment from being transported along the coast, causing "sand starvation" on the downdrift side. The resulting erosion can be spectacular. Such a starved situation exists on Morris Island and Folly Island, SC (fig. 5.19). The two islands sit in the sand transport "shadow" of the Charleston Harbor jetties. Sand that would normally travel southward along the coast is trapped by the jetties resulting in severe erosion of both Morris Island and Folly Island. The jetties were built in the 1890's. A 1935 Army Corps of Engineers report to Congress (House Document 156, 74th Congress) indicates that erosion rates on Folly Island were 7 feet per year for the island, and as high as 51 feet per year at Stono Inlet. The present day erosion rates vary widely from about 1.5 to 6.0 feet per year according to studies done by the South Carolina Coastal Council. The Corps recommended then, as now, hard stabilization to combat erosion.

*The long-term effects of the Charleston jetties are illustrated in Figure 5.19. When the jetties were completed in 1896, the Charleston Lighthouse on Morris Island (also referred to as the Morris Island Lighthouse) stood some 2700 feet inland. With the jetties cutting off the natural sand transport, starving Morris Island of sand, the shoreline began eroding rapidly and by 1940 had eroded back the 2700 feet to the lighthouse. The lighthouse today stands, slightly tilted, some 2000 feet offshore (fig. 4.16). Total shoreline retreat: 4700 feet in 90 years--over 50 feet per year! The story is just the opposite on Sullivans Island and Isle of Palms, SC, located north (updrift) of the jetties. There the beach has widened over the years.

*A similar situation has occurred with the jetty at Ocean City, MD (fig. 4.15). The jetties blocked the north-south sand transport causing updrift accretion, but the entire island of Assateague Island, VA has migrated landward by a distance equal to its width in less than 50 years.

*The point that needs emphasis here is that of the time-frame of these occurrences. After the Charleston Jetties were built, it took over 40 years for the shoreline to erode back to the lighthouse, and another 50 years to reach the present situation. In less than 50 years Assateague Island migrated back one full island width. The full impact of massive shoreline engineering projects cannot be ascertained within just a few months or even a few years of limited data and observations. Several decades are needed in order to fully understand the system. Unfortunately, most people cannot think (or plan) in a decades-long time frame, leaving our children and grandchildren to be the ultimate witnesses and victims of the impact of projects being designed today. One example is the proposed jetty system at Oregon Inlet, NC. The proposed jetties of over one mile in length will block sand transport to Pea Island, the Cape Hatteras National Seashore, and all the villages therein. A National Park Service panel of distinguished scientists concluded that the proposed sand bypassing system would not prevent such sand loss, but the proposal marched forward. The reason for the jetties is to protect navigation into the inlet and reduce maintenance costs---all in support of a diminishing fishery of overfished waters. In a real sense, the current generation is stealing America's future beaches. In the latter case the theft is subsidized by taxpayers so that a few can make a final profit on the last of another resource. The rule (after the biologist, Hardin) is: You can't do just one thing. Every action in nature has multiple effects.

*Hard Stabilization, a Final Word.--Once thought to be the ultimate solution to shoreline erosion problems, hard stabilization has grown increasingly out of favor. Seawalls have been the "solution" of choice for many years. The story of Cape May, New Jersey has been retold often throughout the Living With the Shore book series. In 1801 Cape May was the first full fledged popular beach resort in America and sparked the beginning of the American rush to the shore. During the next 75 years, six presidents of the United States vacationed at Cape May (7 at Long Branch, New Jersey). At the time of the Civil War it was certainly the country's most prestigious beach resort. The resort's prestige continued into the twentieth century. In 1908 Henry Ford raced his newest-model cars on Cape May beaches. Today, Cape May is no longer found on anyone's list of great beach resorts. The problem is not that the resort is too old- fashioned, but that little beach remains. Seawalls and groin fields were built to try to "save" the beach, but they did not slow the relentless encroachment of the sea. The long-term results are plain to see (fig. 5.5). No beach remained until a recent replenishment project brought it back; temporarily.

*Few question that if you want to protect buildings, massive seawalls will do the job. But do we want to protect only the buildings and not the beach? It is obvious that there are advantages as well as disadvantages to hard shoreline stabilization (Table 5.2). The question now is: which are more important, beaches or buildings?

Soft Stabilization

*Where "hard" stabilization is the construction of "permanent" structures, such as seawalls, to hold the shore in place and protect upland property. "Soft" stabilization implies shoreline maintenance through the addition of new sand to replace the eroding beach, or planting vegetation to hold sediment in place. The goal is to protect property and maintain the economic and environmental value of the beach. The concept of this approach is to work with natural processes, rather than confronting nature.

*Beach replenishment.--Artificial nourishment is the modern method of maintaining a healthy beach to help protect buildings as well as for providing a recreational resource. Beach replenishment involves placing new sand, from some outside source, on the beach. Reconstructing the beach is usually carried out by dredging, but sometimes dump trucks are used to bring in sand (e.g., Virginia Beach, VA; North Myrtle Beach, SC after Hurricane Hugo). Sources of sand are the continental shelf, inlets and associated tidal deltas, lagoons (not commonly used anymore because of improper sand quality and environmental problems) and inland sand pits. Beach replenishment is the most important, though not the only, form of soft stabilization. Replenishment appears to be the "wave of the future" in all states with heavy shoreline development. On the east coast of the United States more than 100 beaches have been replenished since 1965, about 40 beaches have been replenished along the Gulf of Mexico shoreline, and 30 along the California shoreline (Table 5.3; Leonard, Dixon and Pilkey, 1990; Pilkey and Clayton, 1989; Dixon and Pilkey, 1991; Clayton, 1991; Pilkey, 1988). Miami Beach, the largest and most successful of all, cost about five million dollars per mile for 10.5 miles of beach (fig. 5.20).

*There are strong regional differences in the durability (lifespan) of replenished beaches. There are some thumbnail numbers that communities can use to guess how long their new beach will last. On the USA east coast barrier island shoreline (where the most information is available) replenished beaches, from Cape Canaveral, FL to the south, last on the order of nine years. Between Cape Canaveral and the Florida state line, five-year lifespans are typical. Between Florida and New Jersey, 2-4 years of replenished beach life can be expected. Along southern New Jersey, a two-year lifespan is more or less typical.

*In most cases, replenished beaches erode much faster than the natural beaches that preceded them because the "new" beach is just piled on the top of the upper beach, resulting in a beach that is steeper and out of equilibrium with the wave climate. Many of the standard design parameters used to predict the durability (lifespan) of artificial beaches (such as grain size and beach length) seem to have little to do with the length of life of replenished east coast beaches. Instead, storms and storm frequency are the most important factors. It is fair to say that current design methods for replenished beaches have failed to predict life spans and nourishment intervals (the time span between nourishment projects). Experience on the east coast of the USA has shown that the best way to predict how well a beach will last is to pump sand up and watch it! The first try will provide a gauge for the second and the third tries---beach nourishment is very expensive. In other words, despite all the mathematical and physical models, high-technology designs, and predictions, each individual beach replenishment project is really just an experiment---a very high-priced experiment.

*The cost of replenishing open beaches by pumping sand from offshore can usually be assumed to be on the order of a bare minimum of 1 million dollars per mile of shoreline per nourishment project. One million cubic yards per mile is a moderate-sized replenishment project and dredged sand costs anywhere from $2 to $12 per cubic yard, depending on many factors. The estimate of the 50-year cost of replenishing a 36-mile reach of New Jersey beaches is $3 billion! Replenishing about 5 miles of Folly Beach, SC in 1993 cost around $12 million. The nourishment interval for Folly Beach was predicted to be eight years, but based on previous experience in similar areas it probably should have been only 1 or 2 years. And in fact, most of the dry replenished beach disappeared from Folly Beach by 1995 and without the passage of a significant storm! The 1990s projected costs for all South Carolina beach nourishment requirements was $65 million which was a highly optimistic estimate based on a ten-year nourishment interval. Clearly, beach replenishment is a costly procedure.

*Unfortunately, many of the costs of a beach replenishment project are hidden or not stated clearly at the beginning of a project when the community is deciding if beach nourishment is the best alternative. In addition to the per-cubic-yard of sand cost, there are the costs of the project design (which, depending on project size and design-phase model testing, can be over 20% of the total) and legal costs incurred (e.g., property condemnations). Also, the true cost of a replenishment project can be partially disguised as part of a cost/benefit ratio. For example, you might be told that replenishment will cost $5 million but the benefit (to tourism; storm damage reduction) will be $10 million for a cost/benefit ration of 1/2 or 0.5, an almost impossibly good ratio. Arriving at the worth of the "benefits" is often questionable, however, and since the same people who are promoting the project are usually the ones calculating the benefit/cost ratios, they will make it appear much more favorable that it actually will be. Be wary of cost/benefit ratios less than one!

*Beach replenishment can also be costly in an environmental sense. Dredging or pumping sand from offshore seems like a quick and simple solution to replace lost beach sand; however, such operations must be considered with great care. The offshore dredge hole may allow larger waves to attack the adjacent beach. Offshore sand may be finer in grain size, or it may be of a carbonate component that breaks up under wave abrasion. In all of these cases, the new beach will erode faster than the original. Dredging may also create turbidity that will kill bottom organisms. We believe the dredging of sand off Boca Raton for their new beach released mud that was responsible for killing coral heads and serpulid worm reefs more than 20 miles to the north. Streams of turbid waters from the surf zone of Miami Beach are still responsible for killing nearby coral heads 14 years after the beach was emplaced. Offshore, protective reefs may also be damaged by increased turbidity. Loss of reefs will mean faster beach erosion, as well as the obvious loss of fishery habitat.

*The impact of beach replenishment on sea turtle nesting remains unclear. Because replenished beaches erode rapidly, they frequently exhibit an erosion scarp (small bluff on the upper beach of 1-4 feet) which prevents turtles from moving ashore. Such scarps are an obstacle for older or handicapped human beach users as well; easy to get down, difficult to get up. Miami Beach, probably because it is made up of irregularly shaped grains of sea shell and coral fragments, is too hard packed for a turtle to excavate for a nest.

*There is another kind of environmental cost. Replenishment raises property values (a kind of government "givings") and has, in a number of cases (Carolina Beach, NC and Jacksonville Beach, FL), led to increased density of development. In such cases, single-family home communities can find townhouses and high-rise condominiums beginning to hug the shore. It is important for a community to deal with the issue of development density restrictions before the new beach comes in.

*Project Promises, Politics, and Predictions.--Replenished beaches, by law, must be justified as storm protection for the community. Forming a new recreational beach is not acceptable as the principle justification for emplacement of a replenished beach by the U.S. Army Corps of Engineers. Of course, the reason most communities want replenished beaches is to improve the economy and the quality of life with a wide and handsome new beach, as well as protection for the buildings that profit from the beach traffic.

*The Charleston District of the Army Corps received considerable local criticism about the Folly Beach, SC replenishment project which disappeared far more quickly than local citizens had been led to believe it would. The Corps had said the beach would not need new sand for eight years (an 8-year nourishment interval). In response to this criticism, District spokespersons noted that there was nothing to worry about because all the sand was still "in the system," just offshore, still protecting the community from storms, that the beach is working "just as designed." This reply has become a common response by Corps Districts to communities where nourished beaches disappear faster than anticipated (e.g., Ocean City, MD).

*At Folly Beach one year after the beach was pumped in, the Corps said that 95% of the beach could still be accounted for. Two years after emplacement, 89% was said to be still in place. Meanwhile, in place or not, city administrators and many local residents are unhappy and unimpressed with the underwater sand. The narrow to non-existent high-tide beach is not what the Chamber of Commerce hoped for, and the storm berm no longer offers much storm protection. Furthermore, the offshore sand (Corps claims to the contrary) does not offer much storm protection, either.

*Figure 5.21 illustrates, in cartoon fashion, what has happened at Folly Beach. Immediately after replenishment, a protective berm exists as well as a wider dry beach (the recreational beach at high tide). The profile also is steepened somewhat, and wave energy begins to redistribute the sand out onto the subaqueous portion of the beach. The sand is moved out beyond the surf zone and no longer offers much resistance to storm waves, especially if storm surge occurs, which it almost always does. The protective storm berm is diminished and the high-tide dry beach is very narrow or absent, i.e., underwater sand offers no space for playing beach volleyball unless the players can hold their breath for long periods of time. This was the state of Folly Beach approximately two years after completion of the project, and six years to go until the projected "next needed" nourishment.

*More replenishment are on the drawing board in South Carolina and other states. Community residents where such projects are scheduled should have a clear understanding of what is in store for them. The Corps' projected nourishment intervals for North Myrtle Beach and Myrtle Beach are 10 years. For Garden City, SC, the Corps says sand will have to be pumped in every six years. These replenished beaches are unlikely to last as long as the Corps has predicted, especially the dry beach and protective berm. Almost certainly the Corps will tell city officials after a year or two that almost all of the sand is in place (offshore), so not to worry. We believe underwater sand doesn't count, and that people should tell this to their local Corps of Engineers District office.

*A Test of Beach Replenishment Design Validity.--Before entering into a beach replenishment program, a coastal community should be wary of overly-optimistic predictions of beach lifespan. Lifespan of a replenished beach is usually expressed as nourishment interval. For practical purposes, the nourishment interval can be defined as the time when one-third to one-half of the replenished beach above the low tide line has disappeared. At this point, a new replenishment project is called for.

*A simple calculation can be made to determine how long the design engineer really thinks the beach will last. Values for initial beach nourishment volume, proposed future renourishment interval, and proposed renourishment volume should be readily available in the beach replenishment design documentation. From these data a crude estimate can be obtained of the time the designer expects the beach to survive. If the proposed total lifespan is greater than the lifespan numbers mentioned at the beginning of the section on beach replenishment above, be skeptical. The design is too optimistic and the actual, long-term costs will be many times greater than the proposed costs. By applying this technique to the data in the design documents, replenishment projects currently underway or being proposed in Sea Bright, New Jersey; Myrtle Beach, SC; and Folly Beach, SC have design lifespans of 30, 36, and 12 years, respectively! These are impossibly optimistic estimates, unless the Atlantic Ocean stops having storms! Less than five years in all cases is more likely!
On the USA Gulf of Mexico and Pacific Ocean coasts, the best approach to estimate the validity of beach durability predictions is to compare them with the replenishment experience of adjacent shoreline communities. Although a rough method at best, such comparisons are the most accurate approach possible. Remember also that a large storm could wipe out the beach the day after it was emplaced. We will not have accurate long-term predictions of replenished beach lifespans until we can accurately predict the long-term occurrence of storms, which of course means we will never accurately predict beach durability, sand volumes required, or costs. Experience is the best teacher. Once a beach has been replenished a few times, the community has a good idea of what the future costs may be and a good basis for judging the feasibility of the replenishment alternatives. A standing rule should be that every replenishment project should include lifetime monitoring as part of the design/plan budget and monitoring costs included in the cost/benefit ratio. Promises will be more accurate, success/failure determined objectively, and a basis provided for adjusting future renourishment plans.

*"Free" Beach Replenishment.--Sand taken from inlet channel and harbor dredging used to be routinely disposed by dumping it out on the continental shelf "out of the way," or piled as dredge spoils on marshes or on the backsides of islands. Such spoil is a waste of a potentially valuable resource and can be put to good use as seen in an example from Bogue Banks, NC.

*The eastern end of Bogue Banks, including the town of Atlantic Beach, has been the beneficiary of two rather extensive replenishment projects at no cost to the community. Dredge spoil from maintenance of Beaufort Inlet was piled up on the backside of the eastern end of the island. As the spoil dumping ground became full, and a new dredging project was about to begin in 1987, the previously dredged material was taken from the original disposal site and placed on the beach from near the Triple S Pier (the easternmost fishing pier), west to beyond Atlantic Beach (fig. 5.22). The beach was widened and sand fencing has resulted in modest dune growth. The project was repeated in 1994. The point here is that all dredged sand, if it is at all suitable for a beach, should not be disposed of as spoil, but should be used for beach replenishment. Atlantic Beach was very fortunate because their beach was replenished for free. Free sand is not likely to be the case too often. However, remember the Sand Commandments. If sand has to be dredged for navigation, that sand should be put back into the nearshore sand transport system at another point. Sand disposed of at sea is lost from the beach/dune system.

*Free sand may come with minor drawbacks as in the case of Atlantic Beach's new beach. The sediment dredged from the inlet channel has a high mud content and contains some oyster shells and shells of other lagoonal bivalves. The shells were protected from abrasion in the muddy, lagoonal environment, so when they are placed on the beach wave action begins to break up the shells creating newly broken, sharp, angular shell fragments, potentially dangerous to beach users. Also, the mud in the sediment is cohesive enough to form small scarps on the beach (fig. 5.23), and packs down into a relatively hard pavement on the upper beach--not ideally suited for sunbathing and general beach "frolicking." The good news is that the beach is there, protecting development behind it. In addition, as the sediment is reworked, the mud is washed away and the sand content is contributed to the recreational beach.

*In recognition that maintenance dredging sand is a valuable replenishment sand resource, the state of Florida has outlawed hopper dredging to prevent loss of sand. The Corps of Engineers continues to dispose of much dredging material offshore, however. Often the dredged sand is not of suitable quality to be used for replenishment, and often there is not beach needing replenishment nearby.

*Beach Scraping (Bulldozing).--Some advocate moving beach sand from the low-tide beach to the upper back beach (independent of building artificial dunes) as an erosion-mitigation technique. A relatively thin layer of sand (1 ft. or less) is removed from over the entire lower beach using a variety of heavy machinery (drag, grader, bulldozer, front end loader), and spread over the upper beach (fig. 5.24). The objectives are to:

o build a wider, higher, high-tide dry beach
-for recreational use
-for storm protection
o fill in any trough-like lows that drain across the beach
o encourage additional sand to accrete to the lower beach

*The newly accreted sand can, in turn, be scraped, leading to a net gain of sand on the manicured beach. The goal of an enhanced recreational beach is achieved for the short term (e.g., Topsail Island, NC; Hilton Head, SC), but the drawback is that no new sand is added to the system. Ideally, scraping is intended to encourage on-shore transport of sand, but most of the sand "trapped" on the lower beach is brought in by the longshore transport. Removal of this lower-beach sand deprives down-drift beaches of their natural nourishment. Three major negative effects of beach scraping are:

o interruption of sediment supply (downdrift erosion)
o steepening of the beach profile
o complete destruction of beach organisms

*The first two of these impacts is known to accelerate beach erosion.

*The technique of beach scraping is widely applied in several Atlantic coast states, but there are few studies of its effectiveness because few projects have been monitored, and those for short intervals only. A general review of scraping projects, including a successful project at Topsail Beach, NC is provided by Wells and McNinch (1991) and McNinch (1989). They note that beach scraping should be regarded as highly experimental, and any community contemplating using this approach should follow their guidelines:

o identify erosion problem and recognize limits of scraping
o assess feasibility (e.g., not feasible for narrow beaches)
o evaluate fill source/beach slope; cost and design
o include long-term monitoring in project plan/budget

*Wells and McNinch (1991) found that scraping was a common emergency response after Hurricane Hugo in South Carolina. As is often the case, under the pressure to repair the beaches quickly, the State's guidelines were not followed and scraping exceeded the recommended one-foot maximum depth. The resulting beaches were of variable configurations.

*Protective beach width may be slightly enhanced over the short term, but this gain is insufficient to provide long-term protection against major storms. Scraped beaches may erode faster during storms than adjacent unscraped beaches, although scraping may make a small contribution to post-storm beach recovery (e.g., Ocean City, MD). At best, the old cliche "more study is needed" applies, and beach manicuring describes the technique. Monies put into such programs probably are better spent on encouraging dune growth, bringing new sand into the system, or accelerating design studies for the more substantial beach nourishment projects that will be needed. In Ocean City, MD, beach scraping did prove to be a short-term deterrent to beach erosion until the community turned to on-going beach nourishment, costing over $63 million between 1988 and 1995. Beach sand also is scraped and bulldozed to build dunes at the back of the beach.

*Dune Building.--Coastal dunes are a common landform at the back of the beach; part of the dynamic equilibrium of barrier-island beach systems. Although an extensive literature exists for dunes (e.g., Nordstrom et al., 1990; Psuty, 1988; Pye and Lancaster, 1993), their protective role often is unknown or misunderstood. Frontal dunes are the last line of defense against ocean storm wave attack and flooding from overwash, but interior dunes may provide high ground and protection against penetration of overwash, and against the damaging effects of storm-surge ebb scour. A detailed study of the South Carolina coast after Hurricane Hugo quantified the coastal geomorphic changes induced by the storm and demonstrated the protective role of dunes (Tables 5.4, 5.5, and 5.6). That study concluded that the minimum dune field that survived Hurricane Hugo, and thus protected buildings, was 30 meters (100 feet) wide with dunes about 3 meters (10 feet) high. Most of the buildings damaged or destroyed by Hurricane Hugo were fronted by beaches less than 3 meters (10 feet) wide and dune fields less than 15 meters (50 feet) wide. An important ramification of the Thieler and Young (1991) study is that it provides an objective basis on which to predict damage in other coastal areas for a similar storm.

*Prior to the passage of Hugo, 70% of the 51 km stretch (about 30 miles) of developed South Carolina shoreline impacted by the storm was classified as dune field; that is, one or more continuous, well-vegetated dune ridges. After Hugo, only 15% (less than 8 km--about 5 miles) of the study areas fell into this category (Table 5.4). Hugo destroyed over 28 km (17 miles) of dune fields in just a few hours!

*Wide dune fields (both natural and bulldozed) were a main line of frontal defense against property damage during Hugo. Dune field widths were narrowed by Hugo (Table 5.5) but where the widest and highest dunes existed, property damage was less. A price was paid, however. Almost one half of the study area shoreline (49%) had dune fields greater than 30 m (100 feet) in width before Hugo. After Hugo, only 21% of the study area had dune fields greater than 30 m (100 feet) wide remaining.

*Beach width also played a role along with dune field width and height in protecting property during Hurricane Hugo. The Thieler and Young (1991) study showed this relationship for the areas classified as "new gap" after Hugo. New gaps are defined as areas where buildings were completely destroyed and/or removed from their foundations by the storm. The vast majority (84%) of buildings so damaged were fronted by the "deadly" combination of beaches less than 3 m wide and dune fields less than 15 m wide. Recall that beach widths are consistently less in front of seawalls.

*The conclusions based on a specific coast for a specific storm, e.g., Hurricane Hugo in South Carolina, may not necessarily be fully applicable to other geologic settings and storms of different intensities, tracks, and durations. However, Hugo provided a general experience for predicting property damage in other developed areas. Obvious high-damage areas will most certainly be shoreline stretches with narrow beaches, low-elevations, and narrow or absent dune fields.

*Dunes are critical coastal geomorphic features with respect to property damage mitigation. Prior to strict coastal-zone management regulations, frontal dunes were often excavated for ocean views or building sites, or notched at road termini for beach access. These artificially created dune gaps are exploited by waves and storm surge (fig. 5.25), and by storm-surge ebb flows. Wherever dune removal for development has occurred, the probability is increased for the likelihood of complete overwash and possibly inlet formation. The combined threats of storm flooding, inlet formation, and the burial of roads by overwash sand make areas of dune removal prime danger zones for evacuation in case of a hurricane warning. Dune gaps can be refilled (plugged); many with just a few truck loads of new sand. As we will see (Chapter 6), maintaining dunes in the interior of islands is an equally important means of property damage mitigation.

*Plugging Dune Gaps.-- Notches cut in dunes for beach access, views and housing sites are naturally exploited by waves and storm surge; increasing the potential for storm damage to development behind the notch. Plugging dune gaps is a simple and relatively inexpensive measure to mitigate the effects of these artificially created overwash passes.

*Nags Head, NC has several stretches of shoreline where dunes are missing, mostly in front of motels. Although the gaps are large, they could be plugged to increase protection from moderate storms. Another large gap in the very center of Nags Head has possible implications for evacuation as well as for property damage. The only mainland access (and thus, evacuation route) to Nags Head and Hatteras Island to the south is US Route 64, which stretches across Roanoake Sound and the island of Manteo before reaching the island at Whalebone Junction. The portion of North Carolina's Outer Banks from the Virginia border to Oregon Inlet, a distance of over 45 miles, is not technically an island, but a spit. Numerous historic inlet locations, however, are testimony to the fact that this was a true island in the past, and will likely be again in the future. The processes are the same as for a true barrier island, and we use the terms "island" and "spit" interchangeably here. This low-elevation area was made more vulnerable because essentially all of the dunes were removed for development (fig. 5.26). The potential flooding of Whalebone Junction several hours before a storm hits, and while evacuation will still be ongoing, is exacerbated by the lack of dunes. Rebuilding the dunes to close the large gap here is a very inexpensive way to "buy" several more hours of safe evacuation time when the inevitable storm bears down on Nags Head.

*Sand fencing and artificial plantings of dune grass to build (or rebuild) dunes is most effective when property is set back far enough to provide is adequate space for dunes to build and stabilize in a natural equilibrium profile and location. In a case like Bogue Banks it helps that the island has a very high sand-supply (i.e., meaning that geologic conditions are right for a lot of sand to be moving onshore). In contrast, islands with low sand supplies defy efforts to build dunes artificially. The post-Hurricane Hugo sand fencing project at Folly Beach, SC trapped little sand and much of the fencing quickly washed away.

*Dune Management.--Having said that dunes provide natural protection and that dunes can be repaired or restored artificially, some qualifications must be stated. A fundamental rule is that "the dune zone may have to migrate if it is to retain its protective characteristics" (Psuty, 1987). Unfortunately, some people view dunes as if these natural sand accumulations can be designed, engineered, and constructed in the same fashion as groins and seawalls. If dunes are to function in their natural protective role, the PAR approach must mimic the equilibrium setting. A dune bulldozed into a nonequilibrium location will not be stable (fig. 5.24). In fact, artificially constructed sand dikes (continuous dune lines as constructed on the Outer Banks during the Great Depression), rock-cored "dunes," and dunes artificially "cemented" in place are like seawalls blocking sediment derivation and migration; creating new problems on other parts of the island including the interior. Dunes are not static, rigid, permanent structures.

*Similarly, the natural vegetation which stabilizes dunes is in an equilibrium with the sediment and biota. The roots of sea oats (Uniola paniculata L.) are colonized by vesicular-arbuscular mycorrhizal (VAM) fungi which improve the grass's uptake of nutrients and water (Sylvia, 1990). Artificial plantings of these grasses do not fare well in pumped in nourishment sands, or where these sands have been used to construct artificial dunes because the VAM fungus is missing. Plant root systems can be inoculated with the VAM fungus in the nursery to improve colonization of the artificial plantings (Sylvia, 1990) but the point is that nature is far more complex than a simple engineering design. Even the differences in grain size and sorting between bulldozed sediment and natural wind-blown sand may influence dune stability and plant growth.

*Principles of Sand Fencing.--Dune gaps and dune lines can be augmented and repaired by encouraging or enhancing natural processes (fig. 5.27). Typically, such augmentation includes the placement of sand fences, recycled Christmas trees, and the planting of dune grasses to trap wind-blown sand. Sand fencing also serves as a barrier to foot traffic over dunes, allowing vegetation to gain a foothold and flourish. To be effective in building dunes, the use of fencing should follow guidelines which have grown out of various studies (e.g., Gares, 1987; Psuty, 1987) and local experience including:

o do not fence on beach because
--landward transport of sand may be reduced
--the small dunes buildup is out of equilibrium
--fencing is likely to wash out in the first storm
o fencing on the face of the dune may encourage seaward dune toe growth
o do not use double rows of dune fencing which act as inpenetrable rather than permeable barrier (blocks inland sand flow)
o do not attach new fence to old fence as dune grows upward
o remove fencing periodically
o vegetate the newly formed dunes with native species
o vegetation is just as effective as sand fences in building dunes over the long term
o trapping sand on the landward side of the dune is as important as trapping sand on the front and top of the dune

*This last guideline is very important because dune width, as well as dune height, affords protection. The principle is often violated when property owners notch the backside of the dune (e.g., driveways, patios, play areas). Post-storm reconstruction is a time when the landward sides of dunes suffer, loss of sand and reduction of width. Instead of placing overwash sand from roads, driveways, and parking lots back onto the dune, the sediment is removed. Remember:
o both dune width and height are important
o keep all the sand in the system (add new sand)
o allow the dune to migrate (maintain equilibrium)
o vegetate with native species

*Unneeded Dune Building.--A sand fencing project completed after Hurricane Hugo along Sunset Beach, NC, consisted of a continuous row of sand fencing, and was emplaced so far seaward on the beach that there is almost no dry recreational beach at spring high tides (fig. 5.28). Sand fencing was probably not needed on this beach because it has a history of natural accretion. In the present situation, the fencing is trapping sand too far out on the beach, rather than where the sand would have accumulated naturally, just a few tens of meters landward at the edge of the maritime vegetation. The current ridge of accumulating sand will be vulnerable to wave attack in future minor storms. The sand fencing should have been placed properly at least five meters from the spring high tide, winter-storm swash line. Sand fences are neither necessary nor desirable in all situations.

*After Hurricane Hugo, an emergency "dune" (really just a sand pile) was emplaced along much of the impacted portion of the South Carolina shoreline, theoretically to protect structures from additional damage due to oncoming extraordinarily high (but still "normal") astronomical tides. The total cost for this emergency operation was $15 million. Federal disaster relief funds were used to pay part/most/some of the cost. Remnants of those dunes still exist as they were subsequently vegetated. How much "protection" these dunes afforded is uncertain because they were only ridges of unconsolidated sand at the time of the high tide, not stabilized by vegetation. It is not clear if the cost of emplacing the sand ridges was worth the small level of protection they could have afforded.

*Living With an Accreting Beach.--Sunset Beach, NC has a problem all oceanfront communities would like to share. This example is included because of the remarkable history of accretion. The island is of low elevation and narrow with high density single-family home development (similar to many barrier islands), but rapid accretion is occurring along the central part of the island. The maximum long-term average annual shoreline change as calculated by the North Carolina Division of Coastal Management is over 8 feet of accretion per year in the central portion of the island. This average erosion/accretion rate is determined over a period of 50 years---the length of time that aerial photographs suitable for documenting shoreline changes have been available. Accretion rates tail off on either side of the central part of the island, and the island's ends have actually undergone long-term erosion.

*The beach has built out so much in the vicinity of the fishing pier that the pier had to be extended. Accretion has led to the development of a wide dune field, though the dunes are of relatively low elevation. The original dune field consisted of four poorly defined rows of dunes or beach ridges. Hurricane Hugo removed two of these beach ridges. These dunes were sacrificed to the storm, but they dissipated wave energy, sparing the houses behind them. The post-Hugo situation was one of a flat beach; a typical post-storm beach profile. Accretion began again as before Hugo and post-storm sand fencing was emplaced to help build up the new dunes (fig. 5.28). It may take years, however, for an appreciable volume of sand to accumulate and for the dunes to reach their pre-Hugo size. Current accretion or seaward buildup is generally unusual on barrier islands anywhere in the world, other than spits or islands associated with major river deltas where the effects of high sediment supply are greater than those of the sea-level rise and wave regime. When conditions change, accretion will be replaced by erosion on Sunset Beach in the coming decades.

*No one is exactly sure why Sunset Beach is accreting, or if it will continue. Most likely, the accretion is at least partially influenced by tidal inlet dynamics. Sunset is a very short island, and most of it is protected at least somewhat by ebb tidal shoals which block some of the incoming wave energy. If inlet dynamics change, Sunset Beach may change to an erosive mode. Another possibility is that the artificial relocation of Tubbs Inlet resulted in a new local sediment source and/or change in wave refraction, leading to the accretion.

*Similar areas of accretion occur on the updrift sides of major jetty systems (e.g., Sullivans Island, SC; Ocean City, MD). Where a jetty blocks the longshore drift, beaches widen and dune ridges may accumulate.

*Soft Stabilization, a Final Word.--Soft approaches to dealing with shoreline erosion take many forms, ranging from simple dune grass planting to massive beach replenishment projects. While generally considered a more environmentally sensitive approach to erosion management, questions of long-term impact still remain (Table 5.6). In addition, as suitable sources of replenishment sand become more scarce and more distantly located, the costs, and environmental impacts increase.

*Dune protection and improvement guidelines are being developed by several states and private consultants. Keeping people off of the dunes with prohibitions, dune walkovers, and barriers is the important first step in dune conservation. Many states have strict rules governing how to build, vegetate, and maintain artificial dunes. Guides to building and vegetating dunes are numerous (for example, 1976; 1978; et al., 1982-B; NCDCM, 1988; SCMEP, 1990; 1991; and SCCC, undated) see appendix B under Vegetation or Dune Building.

*Beach replenishment is being billed as the "wave of the future" for shoreline protection and coastal management. We hope we have shown that the costs (in dollars and in environmental concern) may outweigh the benefits. Like most things, if it sounds too good to be true, it probably is.

Relocation: Move em' off the Line

*The most obvious way to avoid a hazard is to stay away or move away from it! So it is with an eroding or shifting shoreline. The prudent planner, recognizing that over the years erosion is likely to occur, will build well back from the shoreline or shore bluff. How far back is a "safe" building setback? That question is difficult to answer and will vary from place to place according to erosion rates and state and local regulations.

*When a building is threatened by erosion, the costs and benefits of moving the structure back from the shore must be weighed along with other alternatives such as hard or soft stabilization. Depending on the nature of the problem, a moveback can compare favorably to these alternatives and prove to be economically and aesthetically superior in the long run.
*An amendment to the National Flood Insurance Program passed in 1987 (the Upton-Jones Amendment) allowed homeowners of threatened buildings to use up to 40 percent of the Federally insured value of their homes for building-relocation purposes. The law recognized relocation as a more economical, more permanent, and more realistic way of dealing with long-term erosion problems. The federal government (taxpayers at large) would pay a relatively small amount to assist relocating a threatened house rather than paying a larger amount to help rebuild it; only to see the rebuilt house destroyed in a subsequent storm, and paying to rebuild again...and again. By March, 1995, North Carolina had claims for over 70 relocations and 168 demolitions, and accounted for over 60% of all coastal claims under the program.

*The National Flood Insurance Reform Act of 1994 terminated the Relocation Assistance Program as of September 23, 1995 and replaces the Upton-Jones program with the National Flood Mitigation Fund. Financed from penalty revenues collected for noncompliance with NFIP requirements, the new program provides state and local governments with grants for planning and mitigation assistance for activities that will reduce the risk of flood damage to structures covered under the NFIP. Demolition and relocation activities are eligible for grant assistance under the program, but now compete with other mitigation approaches, including elevation and floodproofing programs, acquisition of flood-zone properties for public use, beach nourishment activities, and technical assistance. Limits are placed on how much a state or community can receive in a 5-year period under the program (e.g., $10 million state; $3.3 million local community; $20 million collectively within any one state).

*If these monies continue to go to relocation programs, or activities which permanently lower risk, the dollars will be well spent. If they are siphoned off for beach nourishment projects that only delay the inevitable loss, no progress in mitigation was made. And, of course, the questions can be raised: What's the government doing in the insurance business? Why should the taxpayers be bailing out people who choose to invest in very expensive, and very risky, property? The answers include: trying to get property owners to pay part of the disaster cost before the fact, rather than taxpayers being expected to cover all of the cost after the fact; trying to save the taxpayers some money, and educate imprudent purchasers; trying to save us from ourselves.

*Remember that the cost of moving back is likely to be a one-time expense, whereas hard and soft stabilization approaches will be continual expenditures, plus the cost of ongoing maintenance. Furthermore, the big storm most likely will inflict damage to your property in spite of these precautions. In the case of some structures, letting the sea claim the building when its time comes may be the most realistic solution, both economically and environmentally. Relocation is a recommended means of shorefront management only if economically viable. To date, mostly single family houses and small commercial structures have been relocated. The cost to relocate multistory buildings may be prohibitive in many settings; another reason why communities should exert control over types and sizes of buildings. Another approach is to demolish threatened structures and rebuild them elsewhere.

*Cape Hatteras Lighthouse--MOVE IT OR LOSE IT!--The controversy surrounding the options for preserving the Cape Hatteras Lighthouse presents a microcosm of shoreline management issues, particularly with respect to relocation. Located in the Cape Hatteras National Seashore (fig. 1.2), the lighthouse is owned by the National Park Service. Arguably the world's most famous lighthouse, the Cape Hatteras Lighthouse stands 208 feet tall, the tallest brick lighthouse in the United States, and weighs 2800 tons (fig. 5.29). The light has helped warn mariners of the treacherous waters which have given North Carolina's Outer Banks the nickname "Graveyard of the Atlantic".

*The present light at Cape Hatteras was first lighted in 1870 (Table 5.7). It replaced a smaller lighthouse that had far less illuminating power. Since the 1930's, when the present light was first seriously threatened by shoreline erosion, until 1981, the National Park Service (NPS) spent about $15 million on interim protection methods. Many of these shoreline projects were primarily for protection of a U.S. Navy facility located just to the north of the lighthouse, and included groins, beach nourishment, and sandbagging. In 1980 when the light was almost lost to a winter storm, NPS began investigating methods of "long-term" protection in order to find a "solution" to the erosion problem.

*NPS was directed by the Department of the Interior to find a protection method that would meet three criteria: (1) the lighthouse will be saved, (2) the solution will be permanent, and (3) there must not be major recurring costs. Despite all the swirling controversy, an examination of all facts clearly shows that only moving the lighthouse satisfies all three criteria. That conclusion was reached by the Move The Lighthouse Committee which, in 1987, helped convince NPS to re-examine the issue. The same conclusion was also reached by the Committee on Options for Preserving the Cape Hatteras Lighthouse, formed by the National Research Council (NRC) in July, 1987, at the request of NPS. The chronology taken from NPS's Environmental Assessment for the Lighthouse Protection Plan, 1982 is presented in Table 5.7. The shape of the shoreline around the lighthouse bulges unnaturally because of the groin field.

*Figure 5.30 compares the 1872 and present-day shorelines, depicting over 1500 feet of shoreline retreat, and demonstrates that if the lighthouse is not moved, the shoreline will continue to erode past the lighthouse, and the curvature in the shoreline south of the lighthouse will become even more pronounced. Costs to maintain the shoreline at the lighthouse and to the north will continue to increase. Eventually, the lighthouse will be destroyed in a storm and all the money and effort spent to stabilize the shore will have been wasted. In contrast, if the lighthouse is moved, it will be in the same relative position with the shoreline as when first constructed, and will no longer need to have the shoreline stabilized. The groins and sandbags will be removed or destroyed by storms at which time the shoreline will straighten and quickly assume its normal, equilibrium profile and shape. This adjustment in shoreline shape will incorrectly be called erosion by some. All other structures threatened by shoreline adjustment and migration can and should be moved along with the lighthouse or later, as they become threatened.

*The main point to be made by this example is that we as a society cannot afford to stand and fight the sea on all of our coasts (there are dozens of lighthouses to be "saved"). We must plan an organized retreat from the encroaching sea or alternatively face expending vast amounts of money and other resources only to fail and retreat grudgingly in a disorganized fashion. Moving the Cape Hatteras Lighthouse will set a bold example for all coastal zone managers to follow. If a lighthouse can be moved, then most buildings can be moved (technically speaking). Some would argue that no public money should be spent on the structure; that it should go the way of the Morris Island, SC lighthouse (fig. 4.16) or the Cape Henlopen, Delaware lighthouse (fig. 5.31). Similarly, why should taxpayers in Dallas or Des Moines pay to protect private buildings in Ocean City or Shoreville?

*The 10/100-Year Relocation Concept.--The crux of the problem exemplified in areas such as the Myrtle Beach Grand Strand, SC, Miami Beach, FL, and other great oceanfront resort communities is the vast number of high-rise condominiums and hotels right on the shoreline (figs. 5.16 and 5.20, for example). For the present, beach replenishment is economically feasible for these communities because of the large number of people that use the beaches and the enormous amount of revenue generated. The Miami Beach replenishment project, the most successful on the east coast in terms of replenished beach lifetime, has lasted for over 10 years (Pilkey and Neal, 1988). In the Grand Strand, SC, replenishment has to be repeated almost yearly. There will come a time, however, when the economics of replenishment will no longer be acceptable. As time goes by, more and more sand will be needed for each replenishment project. The cost per project will continue to escalate. The time is approaching when serious consideration will have to be given to relocation.

*Does it sound farfetched to move large buildings? The International Association of Structural Movers says that moving large structures is technologically feasible, though expensive. Recall also that relocation can mean demolishing the building and rebuilding it elsewhere. The unanswered question is economics.

*Owners of large buildings should begin researching the economics of the various options. One possibility is a 10/100 year relocation plan in which a relocation strategy is developed within ten years and implemented as necessary over the next century. Background work should be done as quickly as possible, certainly within the next ten years. If the replenishment option is to be continued, financing requirements and non-local sand sources need to be identified, the sand resources acquired, and a timetable for obtaining all the necessary permits established. Cost comparisons of traditional relocation or relocation by demolition and rebuilding must be considered, especially in light of the temporary nature of beach nourishment, and finite sand supplies. It must be ascertained if buildings can be relocated on the present property or off property; within the community or outside. What are the options and questions yet to be raised? The point is that planning must begin now, so that the proper questions can be addressed. All this groundwork must be completed within ten years so that when needed, the plan can be implemented. Such implementation will vary with each island and community, but will certainly be needed for all within 100 years (hence the plan's name). Remember, this problem is being passed on to the next generation, and they, in turn, to their children.

*The Grand Strand and Miami Beach are examples of heavily developed beach communities that will face similar problems in the coming decades. Whatever is done, management actions must be in keeping with regional conditions. Coastal cities and communities must work together in the larger context of natural systems. Sand taken from an inlet and placed on one community's beach is sand that might naturally have travelled down the coast to another community's beach. Long-term effects of the mitigation options are not known, but it is known that taking sand from one stretch of shoreline and placing it on another is nothing more than "Robbing Peter to pay Paul;" someone gains beach at the expense of their neighbor. All sand used for replenishment must come from non-local sources, preferably from the mainland, or well back from the beach/dune system in the case of the Grand Strand.

*Nags Head, North Carolina--Town on the Move.--The retreat philosophy has been successfully implemented by the town of Nags Head, NC, located about 50 miles north of the Cape Hatteras Lighthouse (fig. 1.2). This mitigation strategy stems from a desire to protect Nags Head's family beach atmosphere which attracted the residents in the first place, according to town planner Bruce Bortz. The town adopted building standards more restrictive than required by either FEMA or the North Carolina Coastal Area Management Act (CAMA). Incentives are used to encourage development to be located as far back from the ocean as possible. Because small, single-family structures are much easier to move, the town has limited the development of oceanfront hotels and condominiums. Deep lots running perpendicular to the shore provide considerable room for relocation. The general theme of Nags Head's mitigation plan is the recognition that shoreline retreat is inevitable and that it is far better to adopt a policy of planned retreat than to wait for a disaster to force retreat.

*The costs of the two "soft" solutions legal in North Carolina, relocation and beach replenishment, are compared in Table 5.11. In Nags Head, the area of highest erosion is from Whalebone Junction to the town's southern border (NC Division of Coastal Management erosion data), a distance of about 4.5 miles. Replenishment studies carried out by the Program for the Study of Developed Shorelines at Duke University, mentioned earlier in this chapter, show that for a relatively high wave energy area like Nags Head, the cost of beach nourishment will be approximately $2 million per mile with additional nourishment required every three years---a current average annual cost of $3 million. This expenditure will continue as long as replenishment is the chosen mitigation technique. Because much of the nourishment sand is likely to come from Oregon Inlet to the south, the response of Oregon Inlet to the currently proposed jetties will have a considerable impact on future costs. Thus, not only are the present costs of nourishment high, future costs are certain to increase.

*By comparison, the cost of removing structures from the threatened areas is much less. As of the early 1990s, Nags Head had accounted for 78 of the 379 (21%) Upton-Jones petitions submitted nationwide, 55 of which had been approved (Williams, 1993). Of these 55, 35 requested funds for demolition at an average cost of $74,409 and 19 requested funds for relocation at an average cost of $30,211 (Williams, 1993).

*Removal costs to date are dramatically less than the cost of beach nourishment for the 4.5 miles of South Nags Head. Furthermore, beach nourishment will need to be repeated every three years. In contrast, if all the threatened structures are removed, it will be 20-25 years before the number of threatened structures returns to current levels (according to Nags Head planners predictions based on State of North Carolina, Division of Coastal Management average annual erosion rate data). Thus, the cost difference between the two plans is dramatic. Beach nourishment would cost about $9 million every three years and the retreat option would cost about $2 million every 20-25 years.

*The Need for Long-Term Relocation Planning, Bogue Banks, North Carolina.--A situation to compare to Myrtle Beach, SC is illustrated in the community of Indian Beach on Bogue Banks, NC. The Summerwinds Condominium complex sits on the ocean side of Indian Beach. Over 200 units are located here and the seaward-most buildings sit less than 50 feet from a dune scarp. The shoreline is retreating at an average of about two feet per year. However, the shoreline tends to go back in jumps. For example, the shoreline retreated some 20 feet during a winter storm in 1987.

*The situation here is different because there is only one lone condominium complex sitting next to trailer parks and single family houses. The density of development is not as great as Myrtle Beach, nor is the value of the real estate. The 10/100-year relocation plan also is recommended for Summerwinds and other large condominiums and hotels on Bogue Banks, though the economics will certainly work out differently than for Myrtle Beach.

*Setback for Protection.--On Bogue Banks, NC, the Pine Knoll Shores area includes some of the highest, widest and most stable areas of the island. Much of this area is suitable for development so long as the natural environment is maintained, especially the dense maritime forest in the elevated, middle-to-back areas of the island. Although the frontal dune is high and continuous, it is narrow and eroding. Therefore, the beach front is not suitable for development. Buildings on the ocean side of the island should be set back from the frontal dune and trough-like depressions behind parts of the dune line. A good example of this is the John Yancey Motel. This hotel was built shortly after Hurricane Hazel and was located well back from the water (fig. 5.32). The builders apparently learned a lesson from Hazel and have respected the integrity of the natural topography and vegetative cover.

*Deep Property Lots for Future Relocation.--Some of the deepest property lots anywhere on Bogue Banks are located in Salter Path, including lots greater than 100 feet depth off Salter Path Road (Route 58) (fig. 5.33). Deep lots allow homeowners to relocate houses threatened by erosion to another location on their own property. In effect, lot depth determines possible future on-site relocation.

*Relatively deep lots are found on some other islands (e.g., Pawleys Island, SC), but the norm is to crowd as many rows of homes as possible near the water. Despite this trend, some communities, such as Nags Head, NC, are now requiring people to purchase ocean to lagoon lots in order to provide for relocation. Such forward thinking prepares for the inevitable.

*Relocation, A Final Word.--The 1985 "Skidaway Conference on America's Eroding Shoreline" (Howard, et al., 1985) brought together scientists, engineers, attorneys, planners, and environmentalists to discuss a National Strategy for Beach Preservation. As the participants of that conference so eloquently stated over a decade ago:

*"Sea level is rising and the American shoreline is retreating. We face economic and environmental realities that leave us two choices: (1) plan a strategic retreat now, or (2) undertake a vastly expensive program of armoring the coastline and, as required, retreating through a series of unpredictable disasters."

*Relocation is a viable coastal management tool, and need not be considered only for single-family houses. When you move the structure, the danger is reduced (Table 5.8).

*System-Oriented Mitigation: Preserve-Augment-Repair Nature

*Although the traditional focus has been on the shoreline and island front, the area behind the shoreline is where we live, where we invest our time and financial resources, and where we are in the path of the dynamic processes of the barrier island. Management and mitigation must be based on the natural character of the island, or what its character would be if not covered with buildings and asphalt. The next chapter outlines a holistic approach to mitigation.

*Table 5.1: Property damage mitigation options on the beachfront.

Abandonment
Relocation
Active (relocate before damaged)
Passive (rebuild destroyed structures elsewhere)
Long-term relocation plans for communities
Soft Stabilization
Adding sand to beach
Beach replenishment
Beach bulldozing/scraping
Increasing sand dune volume
Sand fencing
Raise frontal dune elevation
Plug dune gaps
Vegetation
Stabilize dunes (oceanside)
Marsh (soundside)
Hard Stabilization
Shore parallel
Seawalls
Bulkheads
Revetments
Offshore breakwaters
Shore perpendicular
Groins
Jetties
Modification of Development and Infrastructure
Retrofit homes
Elevate homes
Curve and elevate roads
Block roads terminating in dune gaps
Move utility and service lines into interior or bury below erosion level
Zoning, Land Use Planning
Recognize hazard areas and avoid:
Tidal inlets (past, present and future)
Swashes
Permanent overwash passes
Setbacks
Choose elevated building sites
Lower-density development

*Things to keep in mind:
Each island or coastal community is different.
Consider the entire coastal zone not just oceanfront.
Rising sea level must be considered.
Table 5.2: The advantages and disadvantages of hard shoreline stabilization.

ADVANTAGES
o temporarily protects property
o may temporarily prevent shoreline retreat
o low maintenance cost if properly constructed

DISADVANTAGES
o eventually causes loss of the recreational beach
(erosion due to wave reflection/refraction; cuts off
sediment supply)
o increases erosion at ends of wall and/or downdrift
o limits access to beach
o often ugly (loss of aesthetics)
o can be costly (up to thousands of dollars per foot)
o requires regular maintenance (additional cost)
o debris from walls become hazardous objects on beach
or to structures in back of wall during storms

Table 5.3. Partial listing of replenished beaches on U.S. East Coast and Gulf of Mexico barrier islands. New England and Great Lakes beaches are not included. Data are from Pilkey and Clayton, 1989, and Dixon and Pilkey, 1991.

U.S. EAST COAST BARRIER ISLANDS

New York

Saganopack Pond
Macox Bay
Southampton Beach
Great South Beach
Westhampton Beach
Westhampton Dunes
Brookhaven and Islip
Jones Beach
Oak Beach
Gilgo-Cedar Beach
Lido Beach
Rockaway Beach

New Jersey

Sandy Hook
Seabright, Monmouth, Longbranch
Deal
Shark River Inlet
Avon
Belmar
Spring Lake
Sea Girt
Bay Head
Lavallette
Seaside Heights
Seaside Park
Berkeley Township
South Seaside Park
Barnegat Light
Long Beach Island
Harvey Cedars
Surf City
Ship Bottom
Brant Beach
Union Township
Island Heights
Long Beach
Beach Haven
Brigantine
Atlantic City
Ocean City
Ludlum Beach Island
Upper Township
Strathmere
Sea Isle City
Avalon
Stone Harbor
North Wildwood
Lower Township
Cape May
Cape May Point
Delaware

Ft. Miles-Indian River Inlet
Indian River Beach
Beach Cove
Bethany Beach
Maryland

Ocean City

Virginia

Virginia Beach

Sandbridge
North Carolina

Cape Hatteras
Fort Macon
Atlantic Beach
New River Inlet
Topsail Beach
Figure 8 Island
Wrightsville Beach
Carolina Beach
Bald Head Island
Long Beach
South Carolina

Myrtle Beach
Edisto Beach
Hunting Island
Folly Beach
Seabrook Island
Hilton Head Island
Georgia

Tybee Beach

Sea Island
East Florida

Mayport Naval Station
Jacksonville Beach
St. Augustine Beach
Brevard County
Cape Canaveral
Indiatlantic Melbourne
Sebastian Inlet
Indian River County
Vero Beach
Ft. Pierce
Lions Club Beach Park
Jupiter Island
Palm Beach
South Lake Worth Inlet
Delray Beach
Boca Raton
Pompano Beach
Ft. Lauderdale by-the-sea
Hillsboro Beach
Hillsboro Inlet
Port Everglades
John U. Lloyd Park
Hallandale Beach
Hollywood-Hallandale
Hanover Park
Bar Harbor
Miami Beach
Key Biscayne
Virginia Key

GULF OF MEXICO

West Florida

Marco Island
Keewaydin Island
Naples
Vanderbilt Beach
Bonita Beach
Ft. Meyers Beach
Captiva Island
South Seas Plantation
Gasparilla Island
Port Charlotte Beach
Venice Beach
Lido Key
Longboat Key
Anna Marice
Mullet Key
St. Petersburg Beach
Upham Beach
Treasure Island
Madeira Beach
Redington Beach
Indian Rocks Beach
Clearwater Beach
Mexico Beach
Okaloosa County
St. Joseph Spit
Panama City Beach
Santa Rosa Island
Perdido Key
Mississippi

Harrison County

Bay St. Louis
Louisiana

Isles Dernieres

Grand Isle
Texas

Galveston
Corpus Christi
South Padre Island

Table 5.7. The saga of the Cape Hatteras lighthouse.

1870: Existing lighthouse first lighted; at 208 feet it is the tallest brick lighthouse in US. Original distance from the sea: 1500 feet.

1919: Shoreline within 300 feet of lighthouse.

1935: Shoreline migration brings the sea to within 100 feet.

1936: Coast Guard abandons lighthouse. Light moved to steel skeleton tower in Buxton Woods, one mile west. Erosion control attempted with construction of sheet-steel piling.

late
1930's: Civilian Conservation Corps begins dune-building project, hopefully to prevent overwash and to allow future development behind it.

1950: Shoreline stabilized (naturally and temporarily) and Cape Hatteras Lighthouse reactivated by Coast Guard. Ownership of the structure had been transferred to the National Park Service.

1966: 312,000 cubic yards of sand pumped from Pamlico Sound to stabilize the shoreline.

1967: Nylon sand-filled bags emplaced in front of lighthouse to stabilize the shoreline. Some still remained in 1995.

1969: U. S. Navy builds three groins to protect Naval facility and lighthouse. They were destroyed by storms and rebuilt in 1975.

1971-
1973: Two replenishment projects emplaced 1.5 million cubic yards of sand from Cape Hatteras Point to the Lighthouse area. September, 1973 found the sea 175 feet from the old lighthouse ruins and 600 feet south of the present lighthouse.

1978: Water reaches old lighthouse ruins.

1980: March storm washed away remaining ruins of the original lighthouse and water reaches within 70 feet of present lighthouse.

1980: During the summer, NPS received results of study of Cape Hatteras erosion problem, and asked the U. S. Army Corps of Engineers (USACE) to begin evaluation for methods to preserve the light.

1982: Public workshop held April 1-2 in Manteo, NC to discuss alternatives for protecting the lighthouse. Options included a seawall revetment, offshore breakwaters, beach nourishment, additional groin, relocation and no action.

1985: NPS selects seawall revetment as best option.

1986: Move the Lighthouse Committee organizes.

1987: NPS decides to review options, asks the National Research Council (NRC) for help.

1988: NRC final report unanimously selects relocation as the best option.

1989: NPS announces in early summer that relocation is the preferred alternative, and again asks for public input. In December NPS announces that relocation of the lighthouse is the best way to preserve it.

1991: NPS seekS bids for moving designs.

1994: Construction of a fourth groin to protect the southern exposure of the base of the lighthouse begins.

1995: Still waiting to be moved....

Table 5.8. The advantages and disadvantages of relocating buildings back from a retreating shoreline.

ADVANTAGES
o removes threat to building
o allows natural shoreline processes to continue
o preserves the beach
o good possibility of one-time-only cost

DISADVANTAGES
o high cost
o site must be deep enough to allow suitable moveback, or an alternative site must be purchased
o structure must be of a type of design/construction that allows it to be moved, for example, a wood-frame house is easier to move than a cinder-block house on a poured concrete slab.