Long Shore Current and the Moving Shoreline
When waves approach shore and "feel the bottom", water piles up and breakers form. This process proves that a shoreline is not static. Primarily these waves, breaking at an angle to the shoreline, are what generate a long shore current that parallels the shore. The long shore current not only moves water in the surf zone, it also moves sediment parallel to the shoreline. Long shore current is a function of the angle of wave approach. For example, if the waves approach the shoreline from the south, long shore current moves from south to north
Although, long shore current and the resulting transport of sediment is only one of the dynamic processes that constantly alter the shoreline. As waves repeatedly hit the shore, water moves onto the beach and then retreats in a continuous cycle. However, the waves are not all that moves on the shoreline. In fact, the sediment on the shore is also always on the move. Great energy is expended on the beach as waves crash against the shoreline. This energy allows the water to transport sediment. The grains are lifted as the waves in the swash zone move onto the beach, and then the grains are deposited again as the water retreats. As long as the waves hit the shoreline “straight on”, the wave crests are parallel to the shoreline, the sand grains will be picked up and redeposit in the same general area. In this case, no real net movement of sand occurs in the swash zone.
Waves generally do not form parallel to the shoreline, and thus, usually approach the shore at an angle. Consequently, beach sand will have a net movement up or down the beach, depending on the direction of incoming waves. Sand grains are transported as the waves move onto the beach. Therefore, the sand grains are being carried in the same direction that the waves are moving. However, when the water retreats, due to gravity it goes straight back perpendicular to the shoreline and not back in the opposite direction from which it came. Since grains are redeposit as the water retreats, the grains are actually deposited further down the beach or down long shore current. The net overall movement of sand is down current.
* A decrease in pebble size in the direction of long shore drift. * An increase in pebble roundness in the direction of long shore drift. I visited the two extreme ends of the beach, Gore point at the west and Hurl stone point at the east, at each end I measured: * The shape of the beach known as the beach profile, using a tape measurer and a clinometer. A clinometer measures the angle of a slope. * The size and shape of a sample of pebbles.
Investigating the Geographical Processes that are Affecting the Physical and Built Coastal Environment There are three geographical processes that are affecting the physical and built coastal environment, they are; erosion, deposition, and transportation. Erosion is the group of natural processes, including weathering, dissolution, abrasion, corrosion, and transportation, by which material is worn away from the earth’s surface, this is mainly caused by wind, running water, and waves breaking on the coast. Deposition is the depositing something or the laying down of matter by a natural process. Transportation is when sand is moved along the coast by long shore drift. At North Cronulla beach erosion is evident.
coast (as shown in pictures 1 & 2). The area of sea is subject to the
There are many different types of coasts that exist throughout the United States. The south shore of Long Island has a unique types of coast known as a barrier beach. Barrier beaches are long narrow land forms that are composed of sand and other lose sediments. These sediments are brought together by the actions of waves, currents and storm surges. Barrier beaches are subject to constant changes by the same forces. Sand is constantly eroded in one area an deposited in another. Barrier coasts are important for a number of reasons; they protect the mainland of Long Island from the open ocean and flooding during storms, for recreational use and the unique ecosystems which exist on barrier beaches.
walking across them. The lines and pulleys and some parts of the waves are example of
Longshore drift is a process by which sediments are transported from one place to another. When this process occurs, beaches, spits and sandbars are accreted over time. If the process of longshore drift is altered by factors such as stronger winds and stronger currents, beach erosion begins at a faster rate and this may result in many serious problems. The main stakeholders of longshore drift are resort owners. They rely on people to visit their resorts and enjoy the beach. However, if longshore drift erodes t...
Rachel begins by stating that when tides or waves occur in the ocean they don’t just effect the surface but also the deepest levels of the water. How would you know for a fact that the wave currents run deeper than just the surface? Proof given by her illustrates
Think back to your childhood; a time where everything and anything was possible. Magic and imagination was something that was used everyday in your life. Now think about where you are in your life right now. There is no longer any magic or mystery. Neil Gaiman and Antoine De Saint-Exupry write two different novels that include multitudes of fantasy. But in the midst of all of the fantasy is the fact that children and adults think differently. Both of these novels explore the idea that children think positively while adults grow out of that stage, developing a pessimistic way of thinking from what they experience in life.
on to his feet, jumped down to the beach, knelt and swept a double armful of sand into a
The Sun’s radiation heats the upper atmosphere, sending the energy toward the earth’s surface and finally mixes with the planet’s counter-rotational currents, creating jetstream flows. The winds flow over the ocean’s surface creating friction that spawns chops, pushing up the seas forming perfect bands of open ocean swell. Pushed on by gravitational forces, the swells speed away from the winds that they came from, moving across the deeps until they feel the drag of the shallows near the coast. As the swells rise up out of themselves, they peak, curling into the liquid dreams that we surfers ride (Kampton 4).
Semaphore Beach is affected by many factors such as natural processes and human impacts including marine litter and the discharge of stormwater. Therefore, several plans have been employed to ensure that the coast is supported through the method of counteracting erosion. However in the future, many management strategies have been put into consideration as well as the environmental, economic and social impacts as well as the predicted consequences. These impacts include traffic related incidents, noises and air pollution and the disruption of wildlife and the erosion of dunes. A method that should be considered for future management of the beach is the use of a concave sea wall, although efficient, this structure would be quite costly. Without the use of coastal management, Semaphore Beach would be unsupported, therefore negatively being affected by a variety of
Over the past 100 years the Louisiana coastline has suffered greatly from biotic, abiotic, and anthropogenic factors. The abiotic factors include things such as hurricanes or overnutrition that influence the surrounding biota. The biotic factors that contribute to coastal erosion are things like the immigration invasive species and the emigration or extinction of local flora and fauna that help preserve the wetlands. Additionally, there are anthropogenic factors such as pollution that can have strong negative influences on the abiotic and biotic factors of the wetlands. Each one of these factors cause ecological disturbances to the wetlands at a frequency and intensity that is unmanageable for the local flora and fauna. There are currently certain measures that are being taken into consideration to slow or stop the erosion of the Louisiana coastline.
Tides are common features of the ocean. Tides occur when large bodies water rise and fall, because of the gravitational pull of the moon and the sun. Spring tides are especially strong tides; in spite of the name they have nothing to do with the season spring. They occur when the Earth, the sun, and the moon are in a line. Spring tides occur during the full moon and the new moon. Neap tides are especially weak tides. They occur when the gravitational forces of the moon and the sun are perpendicular to one another. When water moves from side to side, it is called a current. Currents move warm and cold water to different parts of the ocean.