How Is Cronulla Council Protecting The Area From Erosion?
Erosion
“In earth science, erosion is the action of surface processes (such as water flow or wind) that remove soil, rock, or dissolved material from one location on the Earth's crust, and then transport it to another location”
In Cronulla and most beaches worldwide that have built up areas behind the sand erosion is always a consideration when building new developments and homes. If erosion becomes too damaging it can greatly devalue the land and home. In places like this is can become a great investment to build a hard engineered beach wall or to put some effort into the conservation of a natural sand dune that is able to protect the area behind it.
PRIMARY DATA TABLE
SECONDARY DATA TABLE
Main Findings
Dune Transect
The dune transect shows how soft engineering protects the land, the dunes, held together by the roots of the trees and bushes on them, stop the powerful waves from causing erosion to the development behind them. The trees hold the sand dunes together in two ways, the first being that their roots are able to lock moisture into the sand and prevent lower down sand from becoming loose and blowing away. This allows the dunes to be more resilient to high winds and gusts which are a common occurrence in a coastal area. The second way the trees allow the dunes to be stronger is by their branches, when sand is blown around by strong winds there is often a branch that is able to get in the way of the moving sand and stop it from blowing off the dune completely as the sand will then drop down too the floor again.
The way the dune is set out also aids in protecting the land behind it from erosion, as you can see the mid dune is set a lot higher up than the beach front which makes it a perfect barrier for water trying to creep up towards the top during king tides. Even more set back is the high dune which is a lot higher than the mid dune, this allows it to be an even greater barrier for waters with the Earth’s sea levels constantly rising and for any sand that may be blown off of the mid dune to not reach the development behind.
The local council of cronulla is also putting in a strong effort in an attempt to protect the dune’s integrity as it is a great asset for the local economy. On most of the dune it is a no people zone and no one is allowed to walk in those spaces, there are some walking paths but the quad bike racing that was once a popular activity on the dunes is no longer legal as they cause too much displacement of sand and soil.
Honeycomb Wall Transect
The honeycomb wall transect is a visual diagram of the hard engineering used at south Cronulla to protect the land behind it from the high tide waves on the beach. This hard engineering is vital for the protection of the coastline from erosion and increases the value of land sitting near the beachfront.
The wall is designed as a honeycomb pattern because there is need for a very strong shape that would have holes in the middle both to stop water from flowing too far up the wall and also to keep the weight of each individual piece to a minimum to assist in the ease of transport.
The construction of the honeycomb wall will also aid in providing a boost to the housing prices of cronulla, specifically those of he houses being directly protected by it. This is due to the buyers feeling a greater sense of security that the land and home will remain valuable going into the future.
The main benefit of the hard engineering used in the honeycomb wall is that it requires little to no maintenance and far less need for rules surrounding its protection compared to the natural sand dunes on the north side of the beach.
The downside to hard engineering is that it does cost money to build and if for any reason it ever gets badly damaged it will require laborious repairs, it also is not as visually appealing as a natural sand dune as it is not as fitting for the environment.
List of Features present at South Cronulla Beach
In this list of features the majority of features that exist are either protections from erosion, through soft or hard engineering, or products of erosion that have already occurred.
Products of Erosion-
Rocky cliffs- The rocky cliffs observed on the far south side of Cronulla beach have been created by erosion from the seawater crashing against the side of the land, this water dislodges pieces of rock over long periods of time and causes a cliff face to be produced.
Sea Caves- The sea caves that can be found at South Cronulla are cause by the waves from the sea crashing into the base of the cliff and breaking away rock from the area to create the depth of the cave.
Headland- Possibly the most longstanding geological feature of the area that has been created by erosion, a headland is made by the water eroding the cliff face against the sea and transporting the rock away to sea creating an indent in the land that is now the beach, when this indent is created it leaves two jutted out pieces of land called headlands.
Protections from Erosion-
Sand Dunes- Sand dunes are an important natural protection from erosion as they block of the land behind them from the wind and water coming from the sea that can damage or destroy infrastructure. These sand dunes are vital for protection as they are a natural piece of infrastructure that costed nothing to create and are a much more visually attractive feature than a man made wall.
Barrier- The Honeycomb barrier wall, as mentioned earlier is an invaluable asset in the protection of the coastline at Cronulla as it is specifically designed and engineered to do just that. It is also very durable and there is no need for the local council to worry about providing protective laws and rules to keep the wall in good condition.
Overall this list of features at South Cronulla is a very useful tool is studying the ways erosion is negatively and neutrally affecting the coastline at Cronulla and also in viewing the ways that the Cronulla City Council is able to provide protection for the coastline from the various forces of erosion that it encounters regularly.
Secondary Data
Collaroy Beach
Collaroy Beach on Sydney’s northern beaches is a classic example of inappropriate planning and shoreline subdivision that took place more than 100 years ago. The original property boundaries extend, and still do, down across the dune onto the beach, with most of the houses and now some high rises built on the beach-dune area. The consequences were entirely predictable, every time the beach retreated during high seas, the then beach shacks were undermined.
Major erosion occurred in 1920, seven shacks fell into the sea in 1944-5, and one was washed out to sea in 1967. Following the 1945 storms the council voted to resume the remaining houses. Instead, within ten years the first block of flats was built and soon after the first high-rise, which in turn was undermined by the 1967 storms. More high rises followed, the next built just in time to be undermined by the 1974 storms. Here the council has allowed initial development in a hazard zone, and later massive over-development even after houses had been washed away.
Collaroy remains a problem area with most of the affected properties fronted by makeshift seawalls. The council has started slowly buying back some properties and hopes the state government will allow massive beach nourishment at some time in the future. In the meantime, every big sea removes the narrow beach and exposes the unsightly and hazardous seawalls on one of Sydney’s premier beaches.
International comparative study.
Hemsby
The cause of the change to the natural environment at Hemsby is the erosion from the rising tides on the waterfront causing the soft soil and sand to be washed into the sea. The change to the environment has been quite heavy, some homes that had 50 foot deep gardens facing the beach three years ago now no longer have gardens at all.
In the short term the erosion at Hemsby will cause houses to fall into the sea and cost local people a lot of money. In the long term without proper prevention measures there could be land hundreds of metres in from the coast that no longer exists due to the massive erosion that have been taking effect in recent years especially with worldwide sea levels rising at the rate they currently are.
The local people who were initially directly affected by the erosion, specifically those who had houses that were in danger of being lost, were resorting to lining up cinder blocks in front of the water to provide whatever protection they could from the water. In recent times the local council and people have made an effort to raise money to build a more permanent, hard engineered wall to properly protect the land and sustain the houses’ value going into the future.
In Hemsby a request was put forward to the federal parliament to allocate $2.3 million to go to building a solid permanent protection for the coastline, however the request was rejected, this makes lack of funds the main reason a greater amount of infrastructure has not been produced to protect the area.
Bibliography
En.wikipedia.org. (2018). Erosion. [online] Available at: https://en.wikipedia.org/wiki/Erosion [Accessed 21 Jun. 2018].
Short, A. (2018). The Impact Of Coastal Erosion In Australia. [online] Coastalwatch.com. Available at: https://www.coastalwatch.com/environment/4524/the-impact-of-coastal-erosion-in-australia [Accessed 21 Jun. 2018].
BBC News. (2018). Cliff-top residents 'need government help'. [online] Available at: https://www.bbc.com/news/uk-england-norfolk-43458926 [Accessed 21 Jun. 2018].