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Beach Dune Erosion

Vegetated sand ridges called dunes, built up by dry beach sand blown inland and trapped by plants and other obstructions, back most beaches. As sand accumulates, the dunes become higher and wider. Plants play a vital role in this process, acting as a windbreak and trapping the deposited sand particles. A characteristic of these plants is their ability to grow up through the sand and continually produce new stems and roots as more sand is trapped and the dune grows. Stable sand dunes play an important part in protecting the coastline.

They act as a buffer against wave damage during storms, protecting the land behind from salt-water intrusion. This sand barrier allows the development of more complex plant communities in areas protected from salt-water inundation, sea spray and strong winds. The dunes also act as a reservoir of sand, to replenish and maintain the beach at times of erosion. Frontal sand dunes are vulnerable. The vegetation can be destroyed by natural causes such as storms, cyclones, droughts or fire, or by human interference such as clearing, grazing, vehicles or excessive foot traffic.

If the vegetation cover is damaged strong winds may cause ‘blowouts’ or gaps in the dune ridge. Unless repaired, these increase in size, the whole dune system sometimes-migrating inland covering everything in its path. Meanwhile, with a diminished reservoir of sand, erosion of the beach may lead to coastal recession. To avoid this, protecting the vegetation is vital. The beach, between high and low tides, is hard-wearing but the sensitive dunes, which we cross to reach it, must be protected also. For this reason damaged and sensitive dunes might need to be fenced and access tracks for vehicles and people provided.

Processes such as waves, near shore currents and tides continually modify shorelines. The ability of beaches to maintain themselves is achieved through these natural forces. The natural process of beach renourishment, sometimes called “dynamic equilibrium”, is how the beach responds to weather. When waves are high during storms or when hurricanes hit the shore, sand is carried from the beach and deposited on the ocean floor. This makes the ocean bottom flatter and makes waves break further from shore and smaller. During subtle weather or erosion, smaller waves slowly shift the sand back to the shore and replenish the beach.

When people build homes or resorts on beaches, the buildings interrupt this natural process because the sand that is usually taken by storms is removed so that humans may build. When erosion catches up with them they scream for help and defense against the angry sea. Hard structures, like bulkheads, seawalls and groins, are built on beaches to prevent erosion, but they usually backfire. In the long run after a beach has been “defended” by a hard structure, the beach will have been carried out to sea while the homes still stand.

Bulkheads and seawalls protect banks and bluffs by completely separating land from water. Bulkheads act as retaining walls, keeping the earth or sand behind them from crumbling or slumping. Seawalls are primarily used to resist wave action. Design considerations for these types of structures are very similar. However, these structures do not protect the shore in front of them. In fact, when bulkheads and seawalls are used in areas where there is significant wave action, they may actually accelerate beach erosion.

This happens because much of the energy of the waves breaking on the structure is redirected downward, to the toe where the wall meets the soft sand or earth. The shore on this side of the bulkhead or seawall is thus subjected too much more of the force of the waves than if there were no wall, and it erodes quickly. Man made structures interrupt wave-driven drift, stealing sand from down shore beaches. In the US, many coastal states, including South Carolina, Georgia and California, have passed laws preventing the destruction of beach dunes.

These laws state that people cannot build houses on the dunes. Boardwalks and other structures that allow people to reach the beach must be approved and be constructed in a way so as to not interfere with the preservations of surrounding dunes. Furthermore, it is illegal to “pick” or otherwise remove vegetation such as sea oats, which help maintain the dunes. Most people who visit the beaches annually are quite impressed by the beauty of the sea oats growing on the primary dunes along the oceanfront. But this hearty grass performs a far more important function than adding its good looks to the scenery.

It helps to hold the sand and protect the dunes from wind and erosion. Since sand dunes are so dry, a 6-inch sea oats plant may have roots, which are five feet long. This long root system helps stabilize the dunes against erosion. In addition, the plant above ground can catch windblown sand to increase the size of the dune. The sea oats are important that Florida law prohibits the picking of them at any time. Driving on the dunes is also prohibited. Also, people are urged to use boardwalks when walking over the dunes in an effort to preserve the beach-protecting sea oats.

Many scientists use the term newjerseyization when referring to the destruction of beaches by hard solutions because New Jersey was one of the first states to start extensive armoring of its coastline. New Jersey has seen about half of its beaches disappear because of human error, and just overlooking the problem. Instead of understanding the nature of the sea, we turn to help from the government and tax money to bail us out. There currently exist about fifty government-funded programs that range from building coastal highways to the massive rebuilding of sandy beaches and costly installation of man-made seawalls.

These programs cost millions and only benefit the owners of the coastline property, while the taxpayers get stuck with the bill. Many states have banned open-ocean seawalls, finally realizing the irreversible damage that they do to beaches. Beach renourishment, to replenish the beaches with more sand, is the most environmentally sound because it causes no real harm in the long run. The cost however, is incredible, and the results are short term. In most cases, replenished beaches must be redone on a regular basis, usually every few years.

In New Jersey for example, the government has already spent almost $100 million to dredge sand from the ocean floor and dump it onto 33 miles of coastline. Ocean City Beach was renourished in 1982 for five million dollars, but washed away in only two and a half months. When beach residents demand something be done about the beach dune erosion, and all the money the is spent on contemptible endeavors to stop mother nature, a storm or hurricane will come along and wipe out the development. Then billions of dollars are spent to rebuild coastline homes and resorts, which set up a repeating cycle of economic and environmental idiocracy.

One day, in a better society, we will save our beaches from development so that everyone is free to enjoy them in an unhampered, natural state. We will stop wasting billions of dollars in our futile attempts at man-made beach resurrection and pointless rebuilding of homes and resorts. It will become clear that the development of America’s coastline is too costly to maintain and is destroying our beaches. Until then we will scurry to the tiny public designated beach access areas, fight for parking spaces and sunbathing positions, and enjoy one of our planet’s most beautiful assets while we can.

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