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Physical Environment
Landscape
Burwood Beach is a
medium sized beach lying between Little Redhead Point to the south and the
rocky headland separating Merewether Beach to the north. Glenrock Lagoon
discharges intermittently to the ocean at the southern end of Burwood Beach.
The underlying bedrock in this area appears to be the
Newcastle Coal Measures which consist of conglomerate, sandstone, tuff, shale
and coal (Newcastle Geological Series Sheet – SI 56-2).
Bathymetry &
Substrate
The rocky bottom area
of Burwood Beach is divided into two parts. On the south side of the beach is
an extensive area of high profile rocky reef (known as South Reef). This reef
lies in 20 to 25 m water depth. On the north side of the beach there is a
smaller area of low profile rocky bottom in 20m of water broken by a series of
channels (known as North Reef). In the nearshore zone, sediments are coarsest
along the beach and in the shore zone. The sand distribution tends to finer
grades approximately 500m offshore in 12 m water depth. In deeper water (up to
depths of about 60m) the sand becomes coarse again. Beyond 60 m there are mud
deposits on the sea floor Laurie, Montgomerie and Pettit (1977a). Laurie,
Montgomerie and Pettit (1977a) investigated the sea bed contours, geology and
stability of the sea bed (including seismic surveys, test borings, soundings
and sediment sieve analyses) at Boulder Bay (prior to outfall construction),
Burwood Beach and Belmont Beach (see also Boulder Bay and Belmont Beach
outfalls).
Currents, Winds and Waves
Studies
by Laurie, Montgomerie and Pettit (1977a) indicate:
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Ocean currents and local wind are the dominant factors
influencing water movement in the inshore zone.
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The most common circulation pattern found during
summer results from the offshore southerly flowing East Australian Current
(EAC) which generates a large counter-current in the embayment between
Port Stephens and Jervis Bay, which in turn creates an anti-clockwise eddy
between Nobby’s Head and Red Head. While the surface waters are able to
circulate freely, the bottom waters are deflected seaward by the high
profile rocky reef to the south of Burwood Beach.
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At times of easterly winds during summer, the EAC
flows close to the shore along the central coast of NSW generating a
clockwise eddy between Nobby’s Head and Red Head. Under these
conditions, bottom waters are deflected shorewards by the high profile
rocky reef.
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During normal winter conditions slow northerly flowing
currents cross Burwood Beach. The velocity of these ocean currents is very
low and often masked by wind-induced currents.
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