Do Adelaides Beaches Need Help by lindash


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									The coast protection strategy                  Sand ain’t sand
Since its formation in 1972, the Coast         Sand composition, grain size and grain shape
Protection Board has performed the             all affect the movement of sand by waves                                                                   Do Adelaide’s
important task of maintaining Adelaide’s       and wind. This means that exactly the right
beaches and minimising the risk of storm       type of sand must be used for beach
                                                                                                                                                     beaches need help?
damage to properties and infrastructure        replenishment.
along the foreshore. The Board’s strategy
                                               Sand of the right type to adequately supply
has been to replenish beaches affected by
                                               Adelaide’s beaches is a limited resource. The
erosion and to build seawalls where needed
                                               offshore site at Port Stanvac has been used
as a last line of defence against storms.
                                               up and the sand building up at North Haven
In the early years sand was trucked from       is too fine. The mining of the Section Bank
Semaphore and Point Malcolm to Henley          could be an option but this might affect the
and Glenelg North, from the Torrens Outlet     Barker Inlet estuarine environment, while
to West Beach and Glenelg North, and from      suitable onshore quarries could lead to           How can I get involved?
Glenelg to Brighton. More recently, sand has   significant transport costs for the taxpayer.     You can take an active role in the
been carted from Semaphore to Semaphore                                                          development of new coastal management
                                               We therefore need to look closely at all
Park, from Glenelg to Seacliff, and from                                                         strategies. Look out for advertisements in your
                                               possible long-term sand sources.
Brighton to Kingston Park. In the 1990s sand                                                     local paper.
was dredged from an offshore site near Port    What does the future hold?
Stanvac and pumped ashore at Brighton.                                                           To register your interest in becoming involved
                                               The cost of managing our beaches continues        or for further information contact:
                                               to grow because of dwindling local sand
                                               sources, seagrass loss, rising sea levels, and    Coast Protection Board
                                                                                                 Department for Environment and Heritage            Our beaches are slowly eroding
                                               the need to bypass sand around the harbours
                                               at Glenelg and West Beach. We need to             GPO Box 1047 Adelaide SA 5001                      due to a combination of natural
                                               develop protection methods that are more          Tel (08) 8124 4877                                conditions and human influences.
                                               economically sustainable.                         Fax (08) 8124 4920
                                               One method is to slow sand movement along
                                               the coast using structures such as groynes and
                                               offshore breakwaters. Another is to recycle
                                               sand more efficiently between different parts
                                               of the coast, for example by installing
                                               pipelines and pumping systems.

                                               A small-scale planned retreat of the foreshore,
                                               pocket beaches and/or rock embankments
                                               are also options that could be considered
                                               either separately or in conjunction with other
                                                                                                 June 2004 • 17202.04
                                               ideas.                                            ISBN: 0 7590 1087 0
                                                                                                                                                                                 Section Bank
                                   What’s so special about our beaches?	               Seagrass – Who needs it?
                                   Adelaide’s beaches have very significant	           An estimated 2700 Ha (34%) of seagrass                                                                        BO

                                   social, aesthetic, environmental and financial      meadows along the Adelaide coast have                                                                             Peninsula

                                   values for the people of South Australia. 	         died since 1950. Poor water quality resulting                                               UT
                                                                                       from stormwater runoff and effluent disposal                                                                      North
                                   They are used for a variety of recreation and                                                                                                                         Haven
                                                                                       has most likely been the cause. 	
                                   leisure activities, provide a unique lifestyle to
                                   local residents and offer protection from storms    Sand that was once trapped by these
                                                                                       meadows has been released and washed
                                   to adjacent buildings and roads. 	
                                                                                       ashore. As a result, the seabed has steadily
                                   However, coastal environments are fragile
                                                                                       become up to 1 m deeper and the wave
                                   and conserving them is a major cost.	                                                                      seagrass loss
                                                                                       energy reaching our beaches has increased.
                                                                                                                                             results in sand
                                                                                       This causes a larger quantity of sand to drift        being washed                                    Semaphore
                                   The river of sand                                                                                             ashore
                                                                                       north along the coast.                                                                                            Port Adelaide

                                   Sand is always moving northward along the
                                   Adelaide coastline – being pushed along by          Rising sea levels
                                                                               Semaphore Park
                                   waves and, to a lesser extent, wind. This ‘river
                                                                                       Sea levels across the planet are slowly rising
                                   of sand’ shifts about 70 000 m3 of sand
                                                                                       because of global warming.
                                   northwards along the metropolitan coast

                                   every year, most of which accumulates at            Rising sea levels increase the natural
                                   Semaphore and North Haven.                          movement of sand up the Adelaide coast

                                                                                       and the consequent rate of beach erosion.
                                   Unfortunately, the natural sand supply to the
                                   southern end of the metropolitan coast is only      Rising sea levels also increase the size of storm

                                   about 10 000 m3 per year. Without some form         waves that reach the shore, and hence the
                                                                                       potential for storm damage.                                                                                               River Torrens

                                   of artificial replenishment, the sand on the
                                   southern beaches would drift away.

                                   The sand moving northwards along the coast                                                                                                                                  West Beach
Did you know that there is less    accumulates south of obstacles such as the

                                                                                                                                                                                            of - s
than one metre of sand above       Torrens Outlet and the harbours at Glenelg and                                                                                                                                 Patawalonga
rock and clay on some of our       West Beach. Sand must be bypassed around

                                                                                                                                                                                    river -
                                   these structures to prevent blockage of the
Thirty years of beach              channels and maintain the natural movement
replenishment has kept sand on     of sand to the north.

our beaches but left many of us
complacent about the ongoing
need for an effective coast                                                                                                                                                                                       Kingston
protection strategy.
                                                                                                                                      fro   m Port Stanvac
                                                                                                                                                       ged                                                        Park
                                                                                                                                                  d red
                                                                                                                                             nd                                                             natural sand supply
                                                                                                                                           sa                                                               of 10 000 m3 per year

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