muriwai coastal process Essay

Over the last 30 years, sand has been needed to replenish the beaches at Brighton and Glenelg North in particular, and this has been taken mostly from Glenelg, the Torrens Outlet, Grange and Semaphore. Sand has also been dredged offshore from North Haven. In all, the average quantity of sand moved along the Adelaide coast has been over 100,000 cubic metres each year.

Wind and waves affect Glenelg as they set up a northward drift of sand along the coast and this type of sand movement is known as littoral drift. During coastal storms, huge quantities of sand are eroded and this does damage to near shore, beach and sand dune areas. Glenelg is not considered to be a stable as beach as many others are. Seagrass loss and seabed instability that affect Glenelg is that a third of seagrass meadows along the coasts of Glenelg has died since 1950 and poor water quality resulting from the stormwater runoff and effluent disposal has most likely been the initial cause. When there are gaps in the seagrass meadows the sand below the meadow edge can be eroded by the waves and this will in turn increase the rate of seagrass loss and make it difficult for plants to recolonise the seafloor, even though the water quality has been improved. Sea levels affect Glenelg as parts of Glenelg are being subsided as a result of climate change and a relative sea level rise of one to two millimetres per year has been recorded for Glenelg. “As a result of the loss of sand from the seabed, the level of the seabed has steadily become up to one metre deeper and the wave energy reaching our beaches has increased.” (Adelaide’s Living Beaches Strategies,

Coastal erosion is the wearing away of land and the removal of beach or dune sediments by

Sand nourishment refers to the replacement of sediment on beaches that has previously been lost, generally through natural processes. It is a commonly used practice in coastal management. Collaroy Beach uses sand nourishment as longshore drift has moved sand, which cannot be replenished as there are rock formations preventing sediment from refilling the beach. Collaroy Beach also does not have an established dune system, and cannot trap sand.

This leaves the sand dunes more susceptible to erosion causing blowouts and disrupting the succession of vegetation in the area. This has been a problem at Studland Bay in Dorset on the south coast of England. Persistent human leisure activities on the dunes has led to substantial erosion in some parts of these dunes which has meant that Management programs have had to been introduced by English Nature. Sand dunes help absorb the pounding of high waves and reduce overwash flooding in storms.

sand being deposited upon it. The only reason why beaches shrink is due to erosion and this

At Nudgee Beach, erosion was found to have occurred on the edges of the mangrove forest and along the mudflat shorelines. Erosion is typically influenced by natural factors and occurs when pieces of weathered rock or soil are moved – typically by wind and water – from one place to another. Shorelines with lots of sediment and sand are more inclined to be effected by erosional progression. Erosion may also be provoked and accelerated by human interference. For example, if the decision to clear trees and plants from an area is made, erosion is likely to occur as the root systems of plants work to hold the soil in place. If these root systems are removed and erosion does occur, environmental conditions – such as; landslides and flooding – are more likely to take place. Erosion may also cause other plants to tip over, have their underground roots exposed and damaged and contribute to the pollution of local waters; as a result of mud and soil runoff [26]. Erosion at Nudgee Beach was likely to have been influenced by natural factors; however, the development and extension of the Kedron Brook golfing course may contribute to the acceleration of erosional processes and further damage the mangrove

At Wanda Beach, the tall trees and scrubs act as a windbreaker which further protects the sand formation. According to the field work results collected using the anemometer (see figure 3), the Aeolian processes at the front and the top of the primary dune is where the wind speed is highest. So it is important to plant plants such as the hairy spinifex to stabilise the sand due to its expansive root system and its ability to survive low water conditions.

* The sand dunes on the beaches. This area is affected by wind erosion as well as the tides if adequate vegetative cover is not present. The main type of erosion, from the sea, takes the sand from the sand dunes as well as the rest of the beach in a rip. The sand is then pulled out to sea where it forms a sand bar. On calmer days, the sand is brought back to the beach.

walkways to prevent human interference. The main reason of dune stabilization is to slow down the speed of erosion. In 1974 the Cronulla beaches were at an all time low and

If you have ever lived in proximity to coastal areas you may have seen coastline erosion first hand. The beaches you frequent during the summer may seem to be getting smaller and smaller every year. Why does your favorite beach seem to be disappearing? Coastal erosion is to blame. The waves, wind, tides and currents all play a part in the mechanism that is coastal erosion. When water and wind batter the shoreline sediments are carried out to sea and deposited on the sea floor or at other points along the coastline. This is called an erosional coastline. This erosion may be very apparent or seem to have happened overnight when it happens due to a large storm or extremely high tide.

Beach nourishment is the physical transfer of sand from an area of excess to where it is being eroded. This often involves dredging and transport of sand by truck or through pipeline. Because of the cost involved, beach nourishment is only used where other strategies prove to be ineffective.

Fine, sandy beaches often occur in areas with light wave action (California's Ocean Resources, 1995). While a more coarse sand is found with heavy wave action (California's Ocean Resources,

Long Island is famous for its sandy ocean beaches. Between the barrier beach and the main coast is the Great South Bay. The beaches and dunes have very different characteristics. The sandy beach is the junction of land and ocean. The sandy beach consists of two zones, the swash zone and the drift line. The swash zone is the area of wet sand, caused by the incoming wave. The drift line is formed by the dead seaweed and other aquatic plants. Behind the sandy beach is the primary dune. The primary dune's main function is to absorb the force of the ocean and protect the great south bay and the island's main coast. In some cases secondary dunes form. These dunes are behind the primary dune and are therefor protected from the ocean. This provides the stability necessary for plant growth. Many time a maritime forests will form on secondary dunes.

It is this soft sand and clay which is easily eroded by the action of waves, as the ocean slowly claims back the region it used to occupy. There are