Coastal Managment Geography Report Essay Example

occurs when the closed entrance prevents water from flowing out to sea and with high amounts of rain, the local area will flood due to it being a floodplain and being very flat. In photo 1. 1, longshore drifts transfers sediment towards the bottom of the image, which is the northern part of the beach. The lagoon entrance is seen in the bottom right of the picture and this is where most of the sediment ends up from this drifting. Photo 1. 2 shows the sand deposition from the longshore drift. It also shows how with low tides the entrance can get blocked as the water is very shallow.

Longshore drift can be very problematic if not managed properly, especially at Narrabeen. The Lagoonwatch System and dredging are two sustainable management procedures. The Lagoonwatch System monitors water level and correlates this with rainfall, barometric, tidal and wave data. If the water levels rise above 1. 2m and a flood is predicted then the entrance is manually opened. Every 3 or 4 years, the entrance is dredged and sediment is transferred to Collaroy Beach where it will eventually end up back in the lagoon due to longshore drift.

Interactions between the hydrosphere, lithosphere and biosphere within the Narrabeen Coastal environment The hydrosphere, lithosphere and biosphere all interact together to make the world as it is today. In the Narrabeen coastal environment all three spheres interact to shape the environment which is constantly changing due to the spheres all being dynamic. The hydrosphere is the interconnecting system of water storage in the atmosphere and lithosphere, the lithosphere is the earth’s solid outer shell and the

biosphere is the surface zone of the earth and its adjacent atmosphere in which all organic life exists.

When one of these spheres changes, then the others are also affected. In the Narrabeen coastal environment, there are many interactions of the spheres. One interaction is at the cliff on the north end of the beach. This cliff is part of the lithosphere and was formed from plate tectonics forcing part of the outer layer up. This rock face has been eroded over time and mainly from the waves which is the hydrosphere. The biosphere is affected from this erosion as these cliffs may have been home to fauna and also on top of the cliff where flora was growing.

If these cliffs eroded then these flora and fauna may lose their habitats and be killed or destroyed and forced to move. Erosion may also create a cave in which animals could live, so the impacts are not all negative. These caves are popular for birds to create nests where they are protected from predators who cannot reach the cliff face. Another interaction is the melting ice in Antarctica leading to higher sea levels (hydrosphere) which push sediment (lithosphere) further towards the beach. Sand bars are formed offshore from this sediment and destructive waves move this sand onshore.

This can create sand dunes that are home for flora and fauna (biosphere) . The vegetation that is growing on these sand dunes acts as a barrier and can protect the environment behind it from the strong winds that blow in off the ocean. This is how a coastal dune is formed through the interaction

of the hydrosphere, lithosphere and biosphere. Photo 1. 3 shows dunes that have formed as a result of the interactions between the hydrosphere, lithosphere and biosphere. Impact of human activity on the functioning of the Narrabeen Coastal Environment The Narrabeen Coastal Environment has been impacted by human activity very significantly over time.

Indigenous people were able to live on the land without harming it or disturbing the ecological balance. Since the arrival of the First Fleet to Australia, humans have impacted the environment which has resulted in large amounts of planning, funding and persistence to ensure that the environment doesn't get impacted to the point where it becomes unusable. The Coastal Management Plan has been introduced to reduce or prevent the impact and work out the best way to manage the Narrabeen coastal environment so that it will be able to be enjoyed for many years to come.

The coastal environment was once undisturbed with no human activity impacting on the ecosystem. Now there are houses and buildings that are within 20 metres of the sea line and large amounts of people utilising the large stretch of beach land at Narrabeen. Photo 1. 3 shows a block of unit built on the edge of the beach. Narrabeen coastal environment would be completely different had humans not interfered with the area. Longshore drift transfers sediment to the northern end of the beach towards the lagoon. This leads to a large sand deposition at the entrance to the lagoon and often it closes because of the amount of sand.

This can lead to flooding and poor water quality so every 3 or 4 years,

sand is dredged and taken back to Collaroy Beach. This allows for water to flow in and out of the lagoon without sand blocking it. This helps the environment to function how it should and is a positive example of human activity. Humans were unaware of the impact of building houses on the floodplain close to Narrabeen beach which led to many houses, shops, schools and other buildings being developed. Many of these buildings are now in danger of being damaged or destroyed by rising sea levels and erosion.

Strategies to protect these buildings have been proposed and used but have not been effective. Strategies included sea walls, sand nourishment, purchasing homes and technological monitoring are are all very costly strategies. Photo 1. 4 and 1. 5 shows the strategy of a sea wall and how it is not always successful when big storms wash away sand and expose rocks. This impacts on the levels of government who have to fund projects where money could be used for other things had coastal development been prevented or better planned. These strategies would all change the way the environment functions and may harm the long term future of the area.

Human impact could of been reduced had the government prevented houses from being built so close to the ocean. A major mistake was to allow houses to be built close to the ocean and they are now at risk of erosion and rising sea levels. This is difficult and expensive to manage and is the reason why most of the impact of human activity is negative on the functioning of the Narrabeen coastal environment. Although

these impacts will continue to happen, some impacts are necessary for the sustainability of the coastal environment.