Explain why beach erosion is problematic at Collaroy-Narrabeen beach and list some potential management strategies to mitigate this issue.
Beach erosion is a problem in the Collaroy-Narrabeen beach region due to properties being allowed to be built on top of the sand dune systems.
Sand dunes offer a barrier of protection to coastal areas during such events as storms or king tides.
The main problem is that because these properties have been built on top of the sand dune systems, when a large storm occurs the dunes are eroded out from under the houses placing them at threat of being washed away.
Suggested management strategies:
- Not allowing people/companies to purchase the land where sand dunes are located to build property.
- Building a sea wall or another man made barrier to act as a defense against the storms and tides instead of the dune systems.
- Government buys back properties.
Compare and contrast the impact of sea-level rise on two areas of Sydney. Which of the two areas is most vulnerable, and why?
I chose the two areas of Maroubra and Sydney/Leichhardt.
Of these two areas I believe the Sydney/Leichhardt region is the most vulnerable area to sea level rise. This is because it is primarily harbor, Sydney harbor, Balmain etc and houses are built right on the banks of the rivers running from Sydney harbor. Maroubra/Coogee ect have beaches and dune systems, this would protect a lot of the beach front property from sea level rises.
In your blog explain in your own words how coastal squeeze arises and how coastal realignment could assist with this problem.
A coastal squeeze arises when a coastal defence system such as a sea wall blocks the intertidal zone of the beach from being pushed back further inland as the level of the sea rises. Coastal realignment may assist with this problem in the way that a new barrier is created further inland than the sea wall. This provides a secondary defence system. The original sea wall is opened partially to allow a new intertidal zone to be created beyond.
This re-creates new ecosystems, new locations for recreational activities and further protection from rising sea levels.
After watching the videos, explain in your blog how groynes and seawalls work.
Groynes work in the way that they intercept longshore flow of water that flows along the beach. They do this by collecting sediment as the water pushes it along the beach. This causes the sediment to be moved into a different area.
Seawalls work as a barricade against storm surges. They are often made with block of cement or sandstone at either a slope or straight. They work in the way that they take the impact of the wave energy, refracting it back to the ocean.
What other solutions have you seen for enhancing the sustainability of seawalls? Write about these in your blog.
Make them more marine friendly. Add artificial “rock pool” habitats for sea creatures to rebuild their homes. Construct the wall with built in pockets so that marine creatures such as snails and sea stars can use these crevices to create new homes.
Write about the costs and benefits of beach nourishment in your blog.
Benefits may include:
1. That beach nourishment is effective at protecting beaches from coastal erosion.
2. This allows ecosystems to establish and grow, enabling an abundance of marine life to live and survive there.
3. Creates actual beaches that can be used recreationally.
Costs may include:
1. In order to maintain the beach it needs to be nourished and built up continuously. This costs money in the form of machinery used to do the nourishment and move the sediment. Its also timely as it takes quite some time to move and build the sediment back into the beach thats preferred.
2. The sand used to re-nourish a beach is collected from somewhere else and brought in to be used. This affects the habitat and ecosystems of the creatures living at the original location of the sand being used.