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The Effects of Coastal Erosion

Presentation on coastal erosion's effects on a beach and the economy

Michelle Bradburn

on 28 April 2011

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Transcript of The Effects of Coastal Erosion

The Effects of Coastal Erosion Coastal erosion: noun;the loss of land from a coast as a result of the force of waves and currents When a large meteorological event strikes a coast, the most erosive waves hit the coastlines and wash away sediment at an incredible rate, leaving nothing but piles of debris and devastation behind. http://www.gulf-shores-alabama.net/hurricane-ivan-before-after-photos.html http://www.artdiamondblog.com/archives/hurricane_katrina/ "Tropical and extratropical storms produce strong winds and high surf, which often cause extensive flooding and coastal erosion. The result is a destabilization of coastal beaches, wetlands, roads, and buildings, which is a continual problem that coastal resource managers must address.” (NOAA, 2010) but how does this occur? http://obsgeogblog.blogspot.com/ What else can cause erosion? Longshore drift waves approaching the coast at an angle result in the gradual zig-zag movement of beach materials along the coast what can we do to fix it? seawall breakwater Groin jetty living shorelines A seawall is typically built along the shorelines of rocky beaches to prevent the cliffs from being eroded.
They are usually made from cement, but can also be built out of large riprap stones or interlocking cast- concrete blocks.
eawalls cannot prevent erosion from happening, but they take the force of the waves and prevent the actual cliffs from eroding.
he seawall is built directly on the face of the cliff which is pounded by the waves, protecting the cliff behind it.
The materials from which the seawall is built will slowly be eroded away by wave pounding, abrasion, attrition, and wave scouring, but it keeps the actual cliff from being eroded. Sawalls, breakwaters, groins, and jetties are called HARDSTRUCTURES http://www.learnnc.org/lp/multimedia/14416 http://upload.wikimedia.org/wikipediacommons/b/b7/Offelmer.jpg Beaches composed of sandy sediment require a hardstructure similar to a seawall, but it is built offshore and it called a breakwater.
Breakwaters are made of large riprap stones, oysters, or interlocking cast-concrete blocks.
As a wave approaches the shoreline, the breakwater slows it down and takes most of the wave’s force, while still allowing the water to pass through and over it.
The water reaches the shoreline, but it hits the shoreline at a much slower rate.
Breakwaters prevent strong waves from washing away sediment. http://www.sandsaver.com/index-1.html On beaches where longshore drift is the dominant erosional process, hardstructures known as groins are most helpful.
Groins can be made from the same materials as seawalls and breakwaters, but they are built perpendicular to the shore instead of parallel.
A series of groins are built from the shoreline and each extends into the ocean.
According to the NOAA Coastal Services Center, “Groins are designed to trap and retain sand, nourishing the beach compartments between them.” (NOAA, 2010)
As the wave hits at an angle, the sand if carried to the updrift side of the groin, creating an updrift of sand.
The sand on the downdrift side erodes, but it is caught on the updrift side of the groin.
When a groin is placed at the mouth of a harbor or channel, it is known as a jetty.
It works the same as a groin, but it is working to keep the harbor or channel open. http://njscuba.net/sites/site_alenhurst_jetty.html http://www.nccoast.org/restoration-education/living-shorelines.asp http://ccrm.vims.edu/livingshorelines/ One thing that may satisfy those who deeply care about the environment and going “green” are living shorelines, which are designed from completely natural products and serve the same purposes as hardstructures.
According to the Mississippi-Alabama Sea Grant Consortium, living shorelines use “plant material, oyster shells, earthen material, or a combination of natural structures with riprap or offshore breakwaters to protect property from erosion.” (MASGC, 2011)
Coastal managers plant trees, grasses, and dump oyster shells in specific locations to aid in the prevention of coastal erosion, while providing a natural habitat for coastal marine life, maintaining coastal processes, and spending thousands of dollars less on coastal protection. The roots provided by grasses and other vegetation planted help the soil to soak up more water, allowing it to hold water instead of letting it flow into coastal communities.
Living shorelines are also much more pleasant to look at, and improve water and overall soil quality.
While these living shorelines do allow natural processes to continue and provide better animal habitats, the living breakwaters work the same as a hardstructure breakwater works, and they will still cause erosion elsewhere. The most important thing to remember about hardstructures is that though they prevent erosion in some places, they further erosion in other places. For example, a breakwater prevents erosion along the length of coastline directly behind it, but causes the beach to the left and right of it to erode further. Along this New York shoreline, several breakwaters have been installed.
Tombolos have formed behind each breakwater, but between the breakwaters the sand has been eroded.
While there is increased erosion in some places, the breakwaters are ultimately keeping the sand on or near the shoreline, providing beaches for recreation and protection from high waves and storms.
Some people may argue that hardstructures interfere with natural processes and habitats, and are thus bad for the environment, but they ultimately protect coastal regions and serve a great purpose along the shorelines of every coastal area ? ? ? ? ? ? ? ? Alabama, Hurricane Ivan Robert Costanza says that the provided protection from coastal wetlands in the United States estimates somewhere around $23.2 billion dollars annually. With the economy where it currently is, the United States cannot afford to let coastal zones fail, so they must focus on keeping these zones intact and protected from high storm surges and winds. attrition and wave scouring: occur when the fallen pieces of the cliff are carried by a wave into the cliffside, causing further weathering. wave pounding:occurs simply when a strong wave pounds a sediment beach or cliff, causing joints to form and fill with air or water. The joints erode further by freeze-thaw weathering, which occurs when water gets into the joints and freezes, thus deepening the joint and allowing water to flow further into it. abrasion: occurs when rocks on the ocean floor are carried by the ocean to a cliff and pound into the cliff, causing pieces of the rock to break off. It is of the utmost importance that coastal zones are protected, because they provide an enormous amount of protection for coastal regions. According to Robert Costanza, Director of Ecological Economics at the University of Vermont, “Coastal wetlands reduce the damaging effects of hurricanes on coastal communities by absorbing storm energy in ways that neither solid land nor open water can.’ (Costanza, 2008) The beach, marshlands, and wetlands are all crucial to the protection of the world’s coastlines, and without these coastal elements, we would most likely have no successful coastal cities. But why should I care? http://sinjori.com/regional/coastal/protection.html http://www.aegweb.org/i4a/pages/index.cfm?pageid=4083 http://scienceray.com/biology/ecology/waves-breaking-tool-wbt/ According to StateofFlorida.com, in 2004 there were roughly 77 million visitors to Panama City Beach, FL, and Florida’s overall “tourism industry has an economic impact of $57 billion on Florida’s economy.” (StateofFlorida.com, 2011) Would you go to the beach during a storm or period of coastal disaster? http://www.uscg.mil/d7/d7dr/D7DRM.asp if there's no beach to play on, fewer tourists head to coastal cities on vacations less tourists=less taxes recieved by the state and less business for companies less taxes recieved by the state and less business for companies=possible bankruptcy for cities and businesses possible bankruptcy for cities and businesses=more unemployment and more money spent through government funded programs for citizens = coastlines are important and worth protecting! According to the National Ocean Service, "Ninety-five percent of U.S. foreign trade enters and leaves the country by ship." (NOS, ) According to the NOS, over half of Americans live in coastal zones. (NOS, 2011) What comes from coastal zones? http://stateofthecoast.noaa.gov/coastal_economy/ocean_economy.html An estimated decrease of over 1,200 beach visits or person-days of beach use
A decrease in beach goer spending of almost $28,000. If Huntington State Beach, CA, closed for ONE day: If huntington state beach, ca, closed for ONE month: An estimated decrease of over 38,000 beach visits or person-days of beach use
A decrease in beach goer spending of almost 864,000. According to the NOS... http://www.destination-southern-california.com/huntington-beach-state-park.html and why preventative measures should be taken all of these are pretty important to our economy, and without coastal zones, we wouldn't have any of this.
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