Identification And Descriptions Of The Coastal Environments Of Long Reef/Collaroy & Hawaii

Introduction:

I was given a task to write a geographical report on the identification and descriptions of the coastal environments of Long reef/Collaroy & Hawaii. Then explain the biophysical processes that forms and transforms the coastal environments being studied. Further, to examine the environmental changes in the coastal regions being studied & how the management of the coastal environment can achieve environmental sustainability. Finally to propose how individuals can contribute to environmental sustainability for these coastal environments.

Long REEF- Collaroy

Long Reef & Collaroy’s coastal environment:

Generally high air pressure as most of the beaches are confronted with off shore winds. This results in slight swells and deposited sand on the shores. Overall the beaches are constructive and are gentle beaches. However there was an incident that occurred early June 2016 were a storm caused huge waves and king tides to destroy 50 meters of Narrabeen and Collaroy beaches, where a number of badly damaged waterfront properties remained at risk of toppling into the sea.’The beach is 50 meters narrower now than it was 3 days ago,’ said Professor Ian Turner, the director of the Water Research Laboratory at the University of NSW. The beaches are protected by sand dunes, dune vegetation, rock walls, rubber flanges & consistent sand nourishment.

Images of the after mass of the 2016 storm:

Map of Long Reef/Collaroy:

Long Reef Beach Pictures:

Collaroy Beach Pictures:

Biophysical processes that form and transform the coastal environments:

Rising sea levels & constructive waves have slowly deposited sand onto the beach, up to the high tide. Onshore wind blow the sediment into a dune profile. Plants trap and build that dune. These plants include swale, spinifex, coastal wattle & banksia. As plants die & decompose nutrients are added to the soil, so plant succession can occur. This environmental service is threatened when people walk through the plants and kill them/ruin the soil. The management strategies to this is to put up fences and paths to guide people away from the plantation. However there is also a fine if people are caught destroying or disturbing the vegetation on sand dunes.

At Collaroy there is a developed dune profile with buildings and roads directly next to the beach. Due to beach erosion, tropical cyclones & climate change the urbanized area must always be protected by sea walls, rubber flanges, rock ruble & consistent sand nourishment to prevent it from being eroded from the sea.

Examine the causes, extent and consequences of environmental change in the coastal environments being studied (human impacts):

After the 2016 storm hit the northern beaches. The government & council stepped in to make changes so the residents of the coast side could live unaffected from the beach erosion, offshore drifts and tropical cyclones that caused the 2016 catastrophe to happen. Rock rubble was put in place & rubber flanges were installed to mitigate flooding. However this is still not enough to prevent the environmental change to stop and as such the beachfront property owners were given an option. To pay $60,000 each for the cost of their interim temporary sandbag sea wall.

There are other options like groynes protecting the sand sediment from longshore drift/ erosion (This would also fix the North Narrabeen problem whereby the lagoon entrance gets clogged up by sand and the council consistently have to dig it out and bring it back up to collaroy). However locals believe it will ruin the beach attraction as it doesn’t look appealing plus stops the regular waves and tides that are a prized part of the northern beaches. People have argued that the council & government should be able to protect their citizens and as such would be required to pay for the required money.

A final solution was proposed which is that North Narrabeen beach (the neighbouring beach), has its property set back further back behind the vegetated dunes. As such the waves can erode the beach and in calmer conditions the beach recovers naturally. This has no cost on any party and requires no public money. However this would mean that the houses & apartments on Collaroys sand dune would have to be demolished or relocated. This would cost millions.

Pictures of Groynes established on beach:

Coastal management strategies that are already in place:

Currently the only action taken is the rock ruble which was installed after the July 2016 storm, sand replenishment which continuously happens with the councils money which bring sand from construction sites and other beaches such as North Narrabeen. Finally rubber flanges which were placed at a similar time as the rock ruble. However the question still remains that if another storm that bad hits will the properties be affected?

Analyze the positives and negatives of these strategies and evaluate how effective these strategies are in achieving environmental sustainability:

Sand Replenishment- Sand replenishment helps the beaches to keep sand dunes, stop erosion and take sand from beaches that have too much of it. So in reality sand replenishment is a great and effective way to achieve sustainability. The only negative is that it requires thousands of dollars each time it is done as it requires a lot of machinery and time plus the construction vehicles are unpleasant to look at and can even be dangers while operated near beach goers.

Rock Rubble- Rock walls are a cheaper option than sea walls and force the waves movement back up to sea stopping erosion from occurring. However beach nourishment using offshore sand deposits every decade or so would also be needed to overcome the adverse effects of a rock wall. Offshore sand deposits are expensive to acquire & as such gives a disadvantage to this solution

Rubber Flanges- Rubber flanges prevent beaches from flooding and sweeping away sand. It is indeed a great option for effective environmental sustainability. However they obviously can’t protect an entire beach and sand will still go through longshore drift. Other sustainability options must also be put in place as it isn’t efficient enough to work on its own.

Hawaii

Hawaii’s Coastal environments:

Hawaii has 750 miles of combined coastline making it the 4th longest coastline in the world & has over 100 amazing beaches throughout the Hawaiian islands. The Island of Hawai‘i lies over or just north of the Hawaiian hot spot and is composed of five volcanoes and one active seamount: Kohala, Hualälai, Mauna Loa, Kïlauea, Mauna Kea and Loihi located offshore. Due to the volcanic activity in Hawaii sand is often seen with different colors such as white, red, green and black. Green sand beach gets its name from the green olivine crystals that make up the sand. The crystals come from the cinder cone next to the beach which was formed during an eruption 49.000 years ago. Hawaii’s popular shorelines attracted millions of tourists each year (In fact 10 million came from around the world in 2018) and is in fact the most common income the Hawaiian people get living there. Hawaiian flora is beautiful and diverse. A subtropical region, Hawaii has a year-round warm climate and soil heavy with volcanic ash. Two elements that play a role in the healthy growing of a wide variety of flowers and plants. There are three categories of Hawaiian flora. Endemic, native and introduced. Endemic refers to those flowers, plants and trees found only in Hawaii. These are the flowering and non-flowering plants and trees that were brought to Hawaii by natural means, such as wind, tides and birds. Native refers to those species occurring in the Hawaiian Islands, but found elsewhere in the world. The third category includes foreign or introduced plant species. These are plants brought to Hawaii by people. Some Hawaiian native plants include. The Hawaii Frangipani, orchids, sugar bushes, lobster-claws & rose-mallows.

Hawaii’s beaches & maps:

Hawaii’s yellow sand (It is said there are only 4 beaches in the world with this sand however it is hard to tell and no one really knows):

Rose-mallows (Hawaii’s flora) the most iconic Hawaiian flower seen on teeky girls and other Hawaiian traditions:

Lobster-Claw (Hawaii’s native flora):

Biophysical processes that form and transform the coastal environments:

The Hawaiian Islands are situated near the middle of the ‘Pacific Plate’ on top of a ‘hot spot.’ This Pacific Plate is almost always moving northwestward at a rate of several centimeters per year, about the same rate as your fingernails grow. This constant northwestward movement of the Pacific Plate over a local volcanic ‘hot spot,’ has produced a series of islands, one after another in assembly-line fashion. The result is a chain of volcanic islands (Hawaiian archipelago) that consists of eight major islands and 124 smaller ones stretching from the Big Island of Hawaii along a northwest line for 1,500 miles toward Japan and the Aleutian Islands of Alaska. In total, the islands spread across an area of 6,459 square miles. The Big Island of Hawaii is currently the largest landmass in the Hawaiian island chain. The eight major islands at the western end of the chain are, from west to east, Ni’ihau, Kaua’i, O`ahu, Moloka`i, Lana`i, Kahoolawe, Maui, and the Big Island of Hawaii.

Examine the causes, extent and consequences of environmental change in the coastal environments being studied (human impacts):

As the hot spot ‘moves away’ from the island (due to the Pacific Plate carrying the islands piggyback-style off to the north-west) the Big Island too will fall victim to subsidence and erosion. Eventually, the Big Island will likely find itself in a similar state to that of Maui Nui. It will become separate and smaller islands as the ocean encroaches on the flanks of each separate mountain. Such is the geologic circle of life beyond the Hawaiian hot spot. This erosion and subsidence will cause citizens on the coast of Hawaii to lose their properties & fall victim to a similar situation as Collaroy & North Narrabeen.

However, volcanic action grows the island and The Big Island is predicted to grow for the next 50,000 years until the hot spot has moved to the new island of Loihi which is currently only a seamount. However the erosion is happening on some parts of the island and are dealt with mainly with sand replenishment and moving rock from the volcano as a rock wall against the oceans waves.

Global warming is also thought to be partially responsible for Hawaii’s Big Island sinking. It is expected that within 100 years the ocean will have sunken Hawaii by 3.2ft (1m).

Shorelines are drastically different through each environment characterized by a number of natural hazards. These include: tsunamis, storm surges, high winds, coastal erosion, sea-level rise, and large waves. Building on eroding coasts ultimately increases vulnerability to all these hazards.

Coastal management strategies that are already in place:

Coastal erosion has been, and continues to be, a major issue in Hawaii. It is estimated that Oahu has lost 25% of its beaches from seawall construction resulting in beach erosion, while 72% of the beaches in Kauai are eroding. In addition, the long-term effects of sea level rise are expected to accelerate and expand beach erosion and result in a landward shift of the beach system. While the State of Hawaii currently designates shoreline development setbacks at 40 feet from the upper reaches of the water line, many counties have chosen to establish stricter coastal construction setbacks based on the rate of erosion over 50-100 year time periods. However, on a short term solution most of Hawaii’s beaches have been building rock walls, sea walls & using sand replenishment. To protect there coast from the ocean surrounding the state.

Analyse the positives and negatives of these strategies and evaluate (make a judgement) about how effective these strategies are in achieving environmental sustainability:

Rock & Sand Replenishment- The sand replenishment techniques used on collaroy are the same in Hawaii however they use Basalt, igneous rock and sedimentary rock from there volcanoes to build the rock walls. The cost of moving it is much less than in Australia and you actually can build a few meters of volcanic rock walls by purchasing it for roughly $1K. It cost $3 million to protect only a few meters (a 5 meters in width car park in Collaroy). The price ratio is mostly due to Hawaii’s consistent supply of volcanic rock from its 5 volcanoes.

Sea Walls- Sea walls in Hawaii are generally stone and cement, however there are a few which were built off coral that were placed there blending in with the natural environment. The seawalls protect Hawaii’s cost from the massive North Pacific swell and waves preventing erosion. However sometimes these walls fail, break or collapse due to too much impact to the waves and deteriorate. They require frequent maintenance or reconstruction and as such are expensive to manage.

Conclusion:

To conclude, I’d like to talk propose how individuals could contribute to achieving environmental sustainability for the coastal environment in Collaroy/Long Reef & Hawaii. Both places suffer strong issues that raise ethical, political & environmental issues. Hawaii is slowly sinking and requires protection against tsunamis, storm surges, high winds, coastal erosion, sea-level rise, and large waves. It deeply depends on its tourist attraction for both large perfect barrel surfer paradise waves & quiet the opposite. Calm, romantic & quiet beaches to sustain the economy on the islands. The question it ultimately faces is “How long can it keep its two very different paradises existent to continue tourism? And is there a way to stop the issues preventing it?”

In the case of Collaroy/ Long reef the beaches sand dunes aren’t capable of keeping together against storms and erosion. So if there are people living on the dunes how can we prevent them from being destroyed? Or is it simply that we must accept the fact that some people must leave their homes behind in order to maintain the beach’s natural condition? People might say that ‘It’s best to not play with mother nature and let her do as she wishes. However is it right to let all these people lose everything they have for this? It’s a hard hitting question.

Different solutions provide different advantages and faults for instants. Experts say that seawalls can sometimes reflect waves and create a worse problem. And groynes can disrupt the natural tides of beaches, destroying habitats.

My proposal is to simply continue protecting the beaches with newer strategies than consistently get more efficient and effective. In the past 40 years. Massive improvements have been made on the study of Beach Erosion, Global Warming and how to prevent these issues. I believe soon we will be able to understand and control these almost unstoppable forces & eventually prevent these issues from ever occurring. But all we can do right now is simply. Donate to organizations helping setup these coastal land protection. Study the geology of erosion, the earth & the ocean as we have been for the past 50 years. Finally, preventing ourselves of using items that build up the planets global warming so we may all live better and safer lives on the beaches everywhere.