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Beaches of the Gulf Coast

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Much of the world’s population lives within thirty miles of a coast, and beaches are perhaps the most popular tourist destinations worldwide. The Gulf of Mexico is no exception: Millions of people make their homes nearby, and many of them spend considerable time at the beach, joined by millions more tourists and seasonal visitors.

In Beaches of the Gulf Coast, Richard A. Davis Jr., a veteran coastal geologist, explores the dynamics of beach formation, providing the reader with a basic understanding of the characteristics and behavior of the beach environment and what causes it to change. He compares natural beach environments with those that have experienced human intervention, and he profiles many of the common plants and animals that grow and live on and adjacent to the beach.

Following the coastline from the Florida Keys around the Gulf Coast to Varadero Beach in Cuba, Davis describes the major characteristics of beaches in each US state, with a final chapter on Mexico and Cuba. Focusing on public beaches, Davis emphasizes the special features of the beaches, indicating whether and how they are nourished—either naturally or artificially—and pointing out which beaches have problems and which ones are doing well.

Including photographs, satellite images, charts, and maps that reveal the natural processes of beach formation and erosion, Davis showcases the beauty of some of the Gulf’s “best” beaches, both popular and remote. Beaches of the Gulf Coast provides a broad range of basic knowledge for all who own beachfront property, who live near the beach, or who simply love the beach and want a better understanding of this special coastal environment.

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11 Chapters

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1. Coastal Processes

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Coastal Processes

WHEN we hear the word beach, the first thing that comes to mind is sand; the next is probably waves. Actually there are multiple processes that impact beaches and control their existence and appearance (figure 1.1). It is appropriate to begin with the most fundamental of these coastal processes: the weather. Then it is important to consider how the waves, which are a result of the weather, impact the beach. These waves also generate currents that are a major element of beach dynamics. Storms, especially hurricanes, are a significant factor in Gulf of Mexico beaches. A process that is always present but is not weather related is the ebb and flow of tides, but tides do not play a major role in Gulf Coast beaches.

Weather

The Gulf Coast is positioned in the latitudes that range from about 18° to 30° north of the equator. This range of latitudes experiences a fairly wide variation in weather patterns. As the seasons change, so do the weather patterns. During the summer the Gulf is within the Trade Winds belt, with the prevailing direction from the southeast. This is the time when tropical storms can impact this coast. In the winter the westerlies prevail as weather systems are moving from the northwest to the southeast. The changes from one pattern to another influence the way beaches respond to the wind and the waves produced by it.

 

2. Beach Geomorphology and Barrier Island Morphodynamics

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Beach Geomorphology and Barrier Island Morphodynamics

BEACHES are one of the most dynamic of all surface environments on the earth. Changes can take place in literally seconds. Major changes are commonly the result of severe storms in only a day or so. This chapter discusses the nature of the beach, its morphology, the process-response systems that cause changes, and the way the beach interacts with the shallow nearshore environment in the seaward direction and the adjacent dunes in the landward direction.

Beach Morphology

Looking at a profile across the beach and its adjacent environments, we find a complex of subenvironments. The beach and nearshore zones as discussed here start seaward with the outer longshore sandbar. This nearshore zone extends to the low-tide line where the beach begins. The landward limit of the beach is located where the morphology changes to a dune environment or, if there is human development, perhaps a seawall. Beginning in the near-shore, subtidal environment are multiple longshore sandbars and intervening troughs (figure 2.1). These longshore bars are typically parallel to the shoreline and are wave formed. There are also places where the shallow water steepens and breaking waves commonly occur (figure 2.2). The number of these longshore bars typically ranges from one to three depending on the availability of sediment and the slope of the nearshore. A gradual slope tends to have three, and a relatively steep slope will commonly have only one (figure 2.3). The number of longshore bars at a given location tends to be the same through time. Waves generally break only over the innermost bar except under storm or high-wave conditions. The less energetic troughs between the bars are where surf fishermen cast their bait in hopes of catching something.

 

3. Beach Materials, Structures, and Sources

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Beach Materials, Structures, and Sources

THE most common term associated with the beach is sand. True, most beaches are predominantly sand, but there are many other kinds of materials that can also be present in large amounts at some locations. In fact, the term sand denotes only grain size; it tells us nothing about the composition of the particles. Sand can be composed of a wide range of minerals. This chapter discusses the range of materials that constitute beaches: their textures, composition, and origins. This information will give us a much more comprehensive appreciation of the beach environment.

Beach Textures

Sand is a particle that is between 0.0625 mm and 2.00 mm, or about 1/16 inch. This range of particle size is part of a comprehensive size classification called the Wentworth Grain Size Scale (table 3.1). Some of the terms for grain-size categories in this classification are quite recognizable, but they also have specific quantitative definitions. For example, the term boulder has a specific definition: any particle between 256 mm and 1048 mm or about 10 inches and larger. The terms cobble, pebble, silt, clay, and mud also have specific quantitative size ranges. Beaches can be composed of boulders, cobbles, or sand (figure 3.1).

 

4. Human Impact on Gulf Beaches

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Human Impact on Gulf Beaches

MOST of the world population lives within an hour’s drive of a beach. The influence of humans on the coast has been extensive and intensive, and it will continue in the future. The entire coastal system has been impacted by various human activities: the dunes, estuaries, tidal inlets, and most certainly, the beaches. This discussion includes the spectrum of human influence on the beaches going back to some of the early efforts to protect and/or control coastal change. Since the 1960s we have made changes in how we manage the coast, including the beaches. These changes have been aimed at being less intrusive into coastal dynamics and have provided more aesthetic methods for beach management.

Human efforts to control some of the changes that beaches experience focus on coastal erosion and inlet management. There have been numerous approaches to these efforts, some that work pretty well and others that definitely do not. The US Army Corps of Engineers has led the way in the effort to eliminate or moderate beach erosion problems. They have taken considerable criticism over the years because of their approaches to coastal management. Most recently the Corps, as it is commonly known, has moderated its approach and the public has been appreciative of their efforts. Now all Gulf Coast states also have agencies that are responsible for coastal management and for regulating various activities there, especially construction. Typically it is necessary to obtain permits for any type of coastal modification from both the federal (Corps) and state government agencies. The current system is not perfect, but it works much better than in the past, and the coast has benefited greatly from this cooperation.

 

5. Common Animals and Plants of the Gulf Beaches and Surf Zone

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Common Animals and Plants of the Gulf Beaches and Surf Zone

ALTHOUGH the beach and surf zone are very dynamic, they do have a community of organisms that is pretty similar throughout the Gulf Coast. Both the plants and animals must be adapted to fairly rigorous conditions: tidal fluctuations, wave attack, wind, little available freshwater, and predators. These conditions limit the diversity of organisms. This discussion does not consider the extremely mobile animals such as birds or fish. The emphasis is on the few common benthic organisms of the beach and surf zone, both mobile and sessile (permanently attached). Others not mentioned here are described in the many books on beach fauna and flora.

Nearshore / Surf Zone

The shallow nearshore zone where waves break and currents can be strong presents a difficult set of conditions for bottom-dwelling organisms. The occasional bivalve or snail may find a place to burrow here to be protected from the typical waves. Epifaunal organisms, which live on the sand surface, are not common due to the wave energy and the mobile substrate. It is important for the wader to be careful of burrowing snails such as Turritella and Oliva, both of which can put a hole in your heel if you step on them. The other creature that can cause injury is the sting ray (figure 5.1). This animal has a stinging barb that can penetrate the foot or heel. The so-called sting ray shuffle is the way to avoid the problem. When walking through the surf zone, it is best to shuffle your feet, thus warning the ray of your approach and sending it on its way.

 

6. Beaches of Florida

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Beaches of Florida

FLORIDA beaches can be easily subdivided into three distinct regions: the Keys, the Gulf peninsula, and the Panhandle. Each of these regions has its own characteristics and its own types of beaches. The three sections are also each oriented quite differently to the primary weather patterns, they have different offshore regions, and they experience hurricanes differently. It should also be noted that these regions are separated by extensive coastal reaches where beaches are rare and poorly developed: the Ten Thousand Islands mangrove system and the Big Bend coastal marsh system (figure 6.1).

Florida Keys

Although not a part of the Florida Keys, the islands of the Dry Tortugas are a part of Florida and have beaches. These islands are associated with extensive reef development on Quaternary carbonates and are occupied only by Fort Jefferson, a national monument, and a Coast Guard station. The beaches there are accumulations of reef debris that is coarse sand and all calcium carbonate (figure 6.2).

 

7. Beaches of Alabama

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Beaches of Alabama

THE coast of Alabama is not very long, but its beaches are almost all well developed. It extends from a portion of Perdido Key on the east through Dauphin Island across the mouth of Mobile Bay (figure 7.1). Like most of the northern Gulf Coast, the Alabama beaches have been severely eroded by tropical storms and hurricanes. Two recent hurricanes have resulted in major erosion of the beaches and destruction of built property: Ivan in 2004 and Katrina in 2005. These took place on a coast that was experiencing tremendous growth and development for the tourist industry. Obviously, good beaches are an integral part of this development, and these storms caused considerable loss of beach sand and tourism dollars.

Hurricanes are very destructive to beaches as well as the built environment. Nourishment is the primary way that beaches can recover from these storms. On the Alabama coast, nourishment took place along both Gulf Shores and Orange Beach in 2001 to mitigate the erosion of Hurricane Danny in 1997. The erosion from Hurricane Katrina required considerable nourishment to bring the beaches back for tourism. In 2006, what is one of the largest nourishment projects on the Gulf Coast was constructed with more than 7 million cubic meters of sand distributed along about 22 km of beach at a cost of $28 million.

 

8. Beaches of Mississippi

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Beaches of Mississippi

THE beaches of Mississippi are found on two distinctly different coasts: the mainland and four barrier islands that are several kilometers from the mainland (figure 8.1). None of the barrier islands is accessible by vehicle. For this reason and because they are mostly public land, the islands are pristine. A regular ferry schedule in spring and summer conveys people to West Ship Island, a federal park. The mainland beaches are among the most beautiful and best cared for along the entire Gulf of Mexico.

Beach nourishment has been common on the mainland of Mississippi. The first such major projects were after Hurricanes Ivan (2004) and Katrina (2005), which hit this coast very hard. A volume of 280,000 m3 of sediment was placed on the eroded beach at Pascagoula with the help of the federal government (figure 8.2). Farther to the west at Ocean Springs the beach is very well maintained. This area is dominated by fine sand with few shells. Wave energy is limited along this coast due to the offshore barrier islands that provide a level of protection. This low wave energy is evidenced by the vegetation near the strand line (figure 8.3). The Ocean Springs beaches also have groins to help maintain beach sediment.

 

9. Beaches of Louisiana

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Beaches of Louisiana

THE beaches of Louisiana are probably the least attractive and least visited on the entire Gulf Coast. This is primarily the result of the Mississippi River and delta dominating the coast of this state, and the fact that only one barrier island, Grand Isle, is accessible by vehicle. There are several kilometers of mainland beaches that are fairly popular.

The river system produces a huge volume of fine sediment that dominates the coast. Much of this fine sediment remains suspended as it leaves its distributary channels, producing muddy water that is not attractive to tourists but is very important for the community of organisms that lives along this coast. The bulk of the sediment discharged by this fluvial system either remains in the Louisiana coastal zone or is transported westward. Some moves offshore and is deposited on the Mississippi Fan in deep water.

The beaches in Louisiana are limited to narrow, low barrier islands formed by reworking of abandoned lobes of the delta and to the low-lying chenier plain of the western portion of the state. In both settings the sand that composes the barriers and their contained beaches is perched on thick mud. As a result, the sand is sinking. The rapid rate of sea-level rise along this coast is causing a problem for the long-term existence of the barriers, and the size and elevation of the barriers make them very vulnerable. In fact, they are eroding rapidly and are regularly washed over by storms that spread the sand landward. Several attempts have been made to halt or reduce this erosion. Unfortunately, the future of these barriers, and therefore the beaches, is not very promising.

 

10. Beaches of Texas

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Beaches of Texas

THE Texas coast is essentially a continuum of beaches with tidal inlets scattered throughout (figure 10.1). With few exceptions, these beaches are on barrier islands that are no more than 7000 years old. Mainland beaches are present between Follets Island and Matagorda Peninsula. This is a distinctly wave-dominated coast with low to moderate energy and a mean annual wave height of about 0.5 m. Because the prevailing wind is from the southeast, much of the coast experiences a northeast-to-southwest longshore transport of sediment. In contrast, from the Rio Grande mouth north to an area known as “Big Shell” in central Padre Island, the longshore transport is in the opposite direction. The passage of cold fronts between October and March produces strong wind from the north that blows generally offshore and dissipates wave energy for a few days each year. This process and the relatively strong prevailing wind have resulted in this coast being considered wind dominated, a more specific category of wave-dominated coasts.

 

11. Beaches of Mexico and Cuba

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Beaches of Mexico and Cuba

OVERALL, the Gulf Coast of Mexico is relatively unpopulated and therefore rather pristine. Areas around population centers of Veracruz and Tampico are exceptions. This chapter considers some of the major places where people will visit. The discussion of the Mexican coast of the Gulf terminates in the Cancún vicinity.

The Cuban shoreline is not well known and is frequented only by non-US citizens at this time. The northern coast just east of Havana is the most popular place to visit and has excellent beaches. There are two styles to the shoreline zone in Cuba, and each is discussed.

Mexico

The beaches are much the same in northern Mexico as they are in South Texas. The back-barrier lagoon here is also called Laguna Madre. Overall, the beaches of Mexico are fine sand and are terrigenous except for the area of Campeche Bay and the Yucatán Peninsula, where carbonate skeletal debris dominates beach sediment. This material is coarser than that on the terrigenous beaches. In the area between the two distinct sediment types the beaches are dominated by a mixture of quartz and carbonate debris, giving the sediment a bimodal texture.

 

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