Waves can be defined as a surface disturbance of a fluid in which energy is transferred. Waves are seen as the main contributing factor in coastal erosion all over the world. Waves come in all shapes and sizes. Different types of waves have been given individual names, depending on their characteristics.
Wave types
Wind Waves
Wind waves are formed when a gust of wind blows over the surface of the water. There is some friction between the bottom layer of the wind and the top layer of the water and this causes motion. This bottom layer is then forced to slow down while the top layers are forced to topple over the bottom layer, causing the wave motion in the ocean. There are a number of factors affecting wind wave height such as water depth,
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Destructive waves are generally created during storm conditions due to strong winds blowing over a large fetch. Destructive waves have a big impact on erosion. With their short wavelength and high steep, they crash down onto the coast and drag out soil and rocks with powerful back washes. Destructive waves undermine cliffs, wash away land, kill vegetation and flood low lying land. Constructive waves are the opposite to destructive waves. With their strong swash, they enrich beaches and coastlines with freshly deposited material. (Geography: An Integrated Approach by David Waugh2000)
Waves erode the coast through 4 different processes. These processes include hydraulic action, corrosion, attrition and abrasion.
Hydraulic action is the direct force of the wave striking the cliff face. When the wave hits the cliff face, air and water are forced into gaps in the cliff face at high speeds and pressures, causing parts of the cliff face to break away.
Corrosion occurs in rocks which are vulnerable to weak acids carried in the ocean. These rocks are dissolved by the acids.
Attrition takes place when the force of a moving wave causes rocks to bump into each other and break
An increase in pebble roundness in the direction of long shore drift. The process of attrition will erode the pebbles. c) A decrease of pebble size in the direction of long shore drift, again attrition is involved. d) Undercutting (active erosion of the cliffs at one end of the bay).
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.
wave to form, the surging tide must meet an obstacle. When the ocean meets the
To do so, various stages of protection work were carried out. The first of these was the main protection of the cliff face; the aim was to prevent any falling rock and also cliff retreat with the hope that this would affect the input sediment rate, slowing it down. An extremely important coastal work implemented at the cliff sites from Hastings eastwards towards Fairlight. It was important however, to implement such works on the cliffs, because of their composition or geology that being soft sandstone with a shingle base all along the coastline.
walking across them. The lines and pulleys and some parts of the waves are example of
Longshore drift influences the deposition and erosion of sediments. Waves erode the coast and transport the eroded material along the coastline. Over a period of time, the material will be deposited on a beach or form a larger feature such as a spit. Groynes are structures built at equal intervals along the coastline. Their purpose is to restrict longshore drift, preventing coastal erosion.
Coastal erosion is a growing problem along the Gulf Coast. Louisiana is one of the coastal states most affected by coastal erosion. Ninety percent of wetland loss in the nation occurs in Louisiana, losing 25-35 square miles per year. At that rate, Louisiana will lose 640,000 more acres by 2050. Many factors contribute to this land loss, such as rising sea levels, subsidence, hurricane storm surge, cold fronts, and human interference. Cold fronts and hurricanes can both have detrimental consequences on the coast of Louisiana (Zhang 2004) (Restore or Retreat 2012). This research shows whether cold fronts or hurricanes have a larger effect on coastal erosion. The researcher will describe how historical and current satellite imagery help in determining the changes in the Louisiana coast. Based on previous research, the researcher believes that hurricanes have more of an effect on coastal erosion than cold fronts due to the high winds and storm surge.
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).
Surfers, swimmers and sunbathers use beaches for recreation. People fish off beaches for food. Since many people take their vacations at the beach, lots of beaches in tropical locations are important to their country’s economy. Entire cities, regions and countries depend on the money tourists spend while visiting the beach. Beaches are naturally very dynamic places, but people try to control them and build permanent structures, such as houses, restaurants, shops and hotels, on or near the shore. The natural erosion and deposition of beaches becomes a problem. Beaches con disappear over time, or even over night during severe storms. Beaches are areas of loose sediment (sand, gravel, cobbles) controlled by ocean processes. Most beaches have several characteristic features. First are offshore bars, which help protect beaches from erosion. Next is the foreshore, which rises from the water toward the crest of the next feature; a berm. On low-lying shores, dunes form behind beaches. Dunes look like rolling hills of sand and are blown into place by the wind. New, smaller dunes are often changing shape as the wind continues to affect them. Waves and currents move the accumulated sediment constantly creating, eroding and changing the coastlines.
Rough waves are an open water phenomenon, in which winds, currents, nonlinear phenomena cause a wave to briefly form that is far larger than the "average" large occurring wave of that time and place. rogue waves can form in large bodies of freshwater as well as the ocean. The first rogue wave confirmed with scientific evidence,it has a maximum height of 25.6 metres (84 ft).rogue waves can also reach up to about 30 meters or 100 feet high. A rogue wave estimated at 18.3 meters (60 feet) in the Gulf Stream off of Charleston, S.C.
Sound waves take the form of compressional waves and are caused by vibrations. Sound waves are distinguished by their speed, pitch, loudness and quality (timbre) (Lapp, 2003). There are a few parts of sound waves that we should be familiar with to better be able to understand the physics of music. The crest is the highest point of a wave, while the trough is the lowest. The wavelength of a wave is the distance between two adjacent parts of a wave, like from crest to crest, or from trough to trough....
In the past, there was some kind of confusion between tsunami and other phenomena that generated similar large waves such as storm waves. Some other people used to think that the tsunamis were tidal waves that are caused by the gravity of the moon and the sun due to the similarity in its appearance to the tides. However, the origin of tsunami differs greatly from the origin of the tides. A tsunami can be generated from different sources (Cartwright and Nakamura 152).
Attrition is the breakdown of rock particles when they hit Otakamiro point and each other causing the base of the headland to erode.