As of habitat, and salinization of soils may

As
the Gold Coat is exposed by having an extensive waterfront, rising sea levels
could wipe out the Gold Coast beaches. When the planet gets warmer, it will
result in the seawater expanding. This is called thermal expansion. The glaciers,
ice sheets or caps would also melt, and the water levels would rise, which
would in turn flood the beaches. In some cases, the beaches would naturally migrate
inland in response. More often than not, the beaches are trapped between the
rising sea levels and structures like roads and buildings, which would not
allow them to travel anywhere. If a beach is caught between the rising sea
levels and the coastal development, it would not be able to retreat inland-
this, in turn, would lead to the beaches becoming narrower. Beaches generally
have a much shallow slope. Hence, even a small amount of sea level rise would
overtake a significant portion of it and impact the beaches.

If
this continues to happen, the loss of beach space would decrease the
recreational area for the people living there. Sea level rise would also result
in loss of ecosystems, for example loss of habitat, and salinization of soils
may change the distribution of plants and animals.

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This
is not only a problem for the habitat, but also sea level rises would cost a
huge sum of money worth of damages and infrastructure. Many of Australia’s roads,
rail, port facilities and airports are on the coastal area near the beach. If
there is a 1.1 meter sea level rise, that would cost more than $200 billion
worth of infrastructure that is at risk. (Fitzsimmons, 2014)

 

Sea
levels are rising internationally, specifically around the Australian
coastline- which would continue to higher up through this century. With global
increases that are consistent, sea levels have been increased in Australia at
an average rate of 2.1 mm/year over the past half century. The sea level rise
projections in Australia show that the progression of sea level rises during
the 21st century will be even better compared to the prior four
decades for all scenarios. Figure 1 below shows that the projected amount of
regional sea-level rise is most significant for RCP8.5 and smallest for RCP2.6-
which is the lowest concentration scenario.

 

Sea-level change around
Australia by 2090 (2081-2100) compared to 1986-2005 for the four concentration
scenarios (RCPs). Source: © CSIRO and Bureau
of Meteorology 2015 (Figure 1).

The likely
estimate of a sea level rise in Australia by the year 2090 is 42 to 82cm higher
than the levels predicted in 1986 to 2005. This level could increase, if a
limit is reached in the global system where the land based ice sheets- for
example the Greenland ice sheet to inevitable melting. It has a very low
probability, but it could happen, therefore it should not be ignored. If it did
happen, the consequences would be disastrous. The total melting of the
Greenland ice sheet would mean that it would add approximately 6 m to global
sea levels. This would mean the global mean sea levels would rise considerably.

The figure 2 below shows the projected sea level rise for major Australian coastal
cities. The coastal capital cities such as Brisbane, Darwin, Perth, Adelaide
and Sydney show a mean increase of 60 to 66 cm by the year 2090 for the high
concentration scenario and 45 to 47 cm for medium concentration scenario.

 

Figure 2: Sea
level predictions for 2030 under the intermediate concentration scenario, 2090
under the intermediate

 

 

 

 

 

 

 

To manage and
mitigate the sea level rise, Australia, or more specifically the New South
Wales and Queensland Governments, created the Tweed River Sand Bypassing
Project. The cost is shared between the New South Wales and Queensland State
Governments, and the Council of the city of Gold Coast. This sand collection
system jetty is a permanent system and it also has been designed for adept
operation, low operating costs and also low maintenance requirements. This
project hinders coastal sand moving towards the entrance of the tweed river in southern
Queensland Australia, and to move it up the coast. This creates and upholds a
clear steering channel at the gate to the Tweed River and to also have a never
ending supply of sand to the placement areas which is southern gold coast
beaches, at an amount unchanging with natural drift rates.

 

The Tweed
River Sand Bypassing system consists of a sand collection port, that has an
overall length of about 450 meters that is constructed perpendicular to the
Letitia Spit beach. This system has been designed in a way that it is able to
operate with up to four jet pumps working simultaneously. The sand slurry is
then produced and is transported through a flume to a slurry pit that is
located on shore. It is then pumped through a 400 mm steel pipeline that is
located under the Tweed River, to one of the two fixed and two temporary
outlets in the Northern and Southern Queensland beaches. Figure 2 below shows
the pipe network in a more clearer perspective.

 

Figure 2:
Pipeline Network (Source: WRL Coastal Imaging, 2014)

 

 

What this
does is that it facilitates the retrieval of sand beneath the jetty and
mechanical bypassing of this sand to any one of the discharge outlets located. This
can be seen from the figure above, which are Point Danger (Snapper Rocks East),
Snapper Rocks (Snapper Rocks West), Duranbah or Kirra Point. It also provides
additional dredging from the tweed river gates and the nearshore areas that are
adjacent to South Head beach and placement in the near shore places between the
Kirra Point and Point Danger to help in maintaining the navigation channel and
to also supply additional supply of sand if it is required. Overall this would
greatly help to minimise the impacts of the rising sea levels.