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11. Beaches of Mexico and Cuba

Richard A. Davis Texas A&M University Press ePub

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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1. Coastal Processes

Richard A. Davis Texas A&M University Press ePub

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.

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4. Human Impact on Gulf Beaches

Richard A. Davis Texas A&M University Press ePub

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.

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2. Beach Geomorphology and Barrier Island Morphodynamics

Richard A. Davis Texas A&M University Press ePub

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.

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10. Beaches of Texas

Richard A. Davis Texas A&M University Press ePub

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.

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