History of the Implementation and Evolution of Sand Nourishment Methods on the Gold Coast

Conference Paper (PDF Available) · September 2013with 71 Reads
Conference: Australasian Coasts & Ports Conference, At Sydney
Abstract
Nourishment will become increasingly important to manage beaches worldwide as recreational beaches become an increasingly more valuable and threatened resource. Nourishment is an essential element of the management of the Gold Coast beaches and unit rates / m3 are competitive with international rates due to the growth of a local dredging industry that has developed innovative dredging techniques and expertise. Beach nourishment, from small to large scale using different sources and methods carried out on the Gold Coast, spans almost 40 years from the early 1970’s and has involved many previously untried methodologies, such as nearshore profile nourishment, that have been proven and have evolved from theoretical to routine. Nearshore nourishment has been particularly important as it allows the huge reserves of sand offshore from the beaches to be utilised at a much lower cost than estuarine or other reserves. . The Gold Coast now uses a number of sand sources for beach nourishment including terrestrial / building sites, river / estuarine, sand bypassing, sand bypassing and offshore. Sand nourishment is often combined with structures, such as groynes and the Narrowneck Reef to maximize efficiency. To date about 49Mm3 of sand nourishment has been implemented and this paper documents this history and lessons learned for application on the Gold Coast and other areas in the future. Key findings and lessons, to date, include:  The Gold Coast beaches have been dependent on ongoing beach nourishment with about 49Mm3 to date.  Alternate strategies and structures to increase the long term efficiency of nourishments and reduce volumes, such as reefs, are being considered.  Considerable experience and expertise has been developed by the growth of the local dredging industry implementing beach nourishment on the Gold Coast. The dredging and deposition methodologies have expanded with experience. This has resulted in competitive dredging rates and allowed innovations in best practice to be developed.  The practice of monitoring the behaviour of the beaches and nourishments with accurate regular surveys, particularly after storms, has provided invaluable long term data and knowledge of the behaviour of the beaches. This data has been used to determine the best methods of nourishment placement and to develop sand bypassing systems and alternate strategies such as reefs. The data has also been used to accurately calibrate and validate various numerical models.  Dredging from offshore and nearshore deposition has proven to be an efficient method of beach nourishment.  Adequate sand reserves in the coastal zone are vital to ongoing nourishment works and policies are needed to protect these resources for future nourishment and the long term health of Gold Coast beaches as there is competition for sand materials for usage for other purposes including land reclamation, land fill, habitat enhancement, landscaping, building materials and other purposes.  The 2 sand bypassing systems have been very effective in maintaining the Gold Coast beaches.
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A History of the Implementation and Evolution
of Sand Nourishment Methods on the Gold Coast, Australia
Angus Jackson1, Phil Hill2, John McGrath3
1 International Coastal Management, Gold Coast, AUSTRALIA.
email: a.jackson@coastalmanagement.com.au
2 Retired Ex Chief Engineer, Gold Coast City Council, AUSTRALIA.
3Executive Coordinator Drainage & Foreshores,City of Gold Coast, AUSTRALIA.
Abstract
Nourishment will become increasingly important to manage beaches worldwide as recreational beaches
become an increasingly more valuable and threatened resource. Nourishment is an essential element of the
management of the Gold Coast beaches and unit rates / m3 are competitive with international rates due to
the growth of a local dredging industry that has developed innovative dredging techniques and expertise.
Beach nourishment, from small to large scale using different sources and methods carried out on the Gold
Coast, spans almost 40 years from the early 1970’s and has involved many previously untried
methodologies, such as nearshore profile nourishment, that have been proven and have evolved from
theoretical to routine. Nearshore nourishment has been particularly important as it allows the huge reserves
of sand offshore from the beaches to be utilised at a much lower cost than estuarine or other reserves. .
The Gold Coast uses a number of sand sources for beach nourishment including terrestrial / building sites,
river / estuarine, sand bypassing, sand bypassing and offshore. Sand nourishment is often combined with
structures, such as the Narrowneck Reef to maximise efficiency. To date about 49Mm3 of sand nourishment
has been implemented and this paper documents this history and lessons learned for application on the Gold
Coast and other areas in the future.
Keywords: nourishment, scarp, nearshore, profile, dredging
1. Introduction
Development upon the historic sand dune areas on
the Gold Coast has resulted in the construction of
seawalls to protect beachfront buildings during
severe erosion. The seawalls act to constrain the
natural behaviour of beaches during climate
variability and major storms. With climate
change and projected sea level rise, vulnerable
beaches will be increasingly threatened.
Nourishment is a key method to protect and
improve beaches, either alone or in conjunction
with structures such as groynes, emerged
breakwaters and reef breakwaters.
Many beaches worldwide, and the associated
economic benefits and infrastructure, will be lost
due to lack of funding or lack of positive action.
The beaches that are well managed and can be
protected will have increased economic value.
For almost 40 years, large scale nourishment
using a number of methods and sources has been
an essential element of the management of the
Gold Coast beaches and unit rates / m3 are
competitive with international rates due to the
implementation of innovative dredging techniques
and the long term expertise gained.
The authors collectively span the 40 years of
nourishment and have been actively involved.
This paper documents the history and practical
lessons learned for future application on the Gold
Coast and other areas.
To date, almost 50Mm3 of sand from various sand
sources has been placed along the Gold Coast
ocean beaches from mobile dredgers and from the
2 fixed bypass pumps.
This paper summarises the operations of mobile
dredgers providing nourishment for Ocean
Beaches. This paper does not include details for
Other dredging and nourishment carried out in
canals and waterways of the Gold Coast.
The 2 fixed sand bypass pumping operations
at the Gold Coast Seaway and the Tweed
River Entrance.
Mobile dredger types used have included:
Suction and cutter suction (CSD) dredgers
pumping through pipelines (and boosters as
required) onto the beach
Trailing suction hopper dredgers (TSHD);
bottom dump, rainbowing and pumping
through pipelines ashore
2. Brief History
A history and timeline of all significant Gold Coast
coastal works was published in 2001 [2]. This
paper will extend the beach nourishment history up
to 2013 and provide lessons and
recommendations based on this history.
1950s and 60s; As a result of severe erosion
associated with greater than average incidence of
cyclones and severe storms, the Gold Coast
beaches were in poor condition. The challenge to
restore the Gold Coast beaches was a learning
experience for the newly formed Qld Beach
Protection Authority and the Gold Coast City
Council (GCCC) Engineers and surveyors. GCCC
hired its first designated Coastal Engineer, Sam
Smith, to carry out beach protection works. In
December 1970 the DHL report, known as ‘The
Delft Report’, was finalised. This report provided
the basis for the coastal protection works and has
guided Gold Coast beach management since then.
Some of the detailed work for this report was
completed by the then Qld COG Chief Engineer,
Brian McGrath who was embedded with Delft
University in the Netherlands to provide local
knowledge and facilitate coastal engineering
knowledge transfer back to Queensland.
.
1970s; In 1974, the first nourishment on the Gold
Coast was implemented using medium and large
cutter suction dredgers pumping through pipes
from the sheltered Nerang, Currumbin and Tweed
estuaries. This was the first major beach
nourishments in Australia and many practical
operational problems were solved by the Council
Engineers and hydrographic surveyors working on
tight budgets and with only 25% State funding.
The Surfers Paradise dredging was done with a
large cutter suction dredger by Westham Dredging,
but the other projects were implemented by the
local dredge contractors with medium sized cutter
suction dredgers. These contractors had created
the canal estates and these contractors were quick
to adapt to ocean beach nourishment. The sand
was pumped to the upper beach and out as far as
practical into the surf zone. Placement in this area
required beach visitors to be kept clear as it
created hazardous quicksand conditions at the
outlet and required heavy equipment on the beach.
Also, the public and media were very quick to
claim the expensive sand had been lost after the
first storms cut scarps into the nourished beach
redistributing it over the active profile. This did not
help in the funding of ongoing works to implement
the Delft recommendations.
In the 1970’s about 3Mm3 of sand was pumped
onto the ocean beaches from estuaries using
cutter suction dredgers.
1980s; Works continued on the erosion hotspots
with the severe erosion at North Kirra addressed in
1985 The north Kirra beach restoration used the
first sand pumped from the offshore sand reserves
that was pumped ashore using a large Belgium
TSHD . Conventional practice worldwide was for
sand dredged from offshore to be pumped ashore
or rainbowed into the surf zone. Both methods are
expensive and to avoid costs and the perception of
upper beach sand being “lost” it was decided to do
a small trial with sand placed nearshore into 6-9m
water depth as part of the Nth Kirra Beach
Restoration Project [3]. Although such nearshore
nourishment had not been used successfully
anywhere else at the time, it was considered low
risk if placed shoreward of about 9m water depth
as artificial storm bars as detailed surveys showed
that the large natural storm bars in this depth
moved onshore over a period of about 18 months
[6]. Surveys confirmed the shoreward movement
and accretion of the visible beach inshore of the
nourishment. Dyed sand samples were also used
to track the sand movement. As a result of the
success and significant cost savings, further large
scale offshore dredging, deposited nearshore was
carried out.
The Gold Coast seaway was constructed by the
Gold Coast Waterways Authority and sand
bypassing operations commenced in 1985/86,
pumping sand via pipeline under the new entrance
and depositing on the beach on the southern end
of South Stradbroke Island. This has created a
good navigation channel through the new entrance
and a new surf location at the discharge.
Dredging of the Tweed R ebb tide delta was
commenced in the late 80s as Stage 1 of the
Tweed River Entrance Sand Bypassing Project
(TRESBP), a joint NSW / Qld / GCCC funded
project.
The 1980s saw the first use of offshore sand
reserves for both onshore and nearshore
nourishment using TSHD. Also the start of sand
bypassing of the Nerang and Tweed Rver
entrances. The introduction of policies to ensure
that all sand excavated within 500m of the seawall
line proved highly successful in providing sand to
the dunal areas.
1990s; In this period annual maintenance
“bypassing” dredging works from Currumbin and
Tallebudgera estuaries continued pumping onto
Palm Beach and Burleigh Beaches respectively
with medium sized cutter suction dredgers.
The Nerang River entrance sand bypassing
continued. Further dredging from the external
delta of the Tweed River entrance was carried out
by TSHD. These included the first Gold Coast
owned shallow draft TSHDs. In December 1999,
the NSW and Queensland State Governments
awarded contracts to a consortium led by
McConnell Dowell Constructors (Aust.) Pty Ltd for
the development and operation of a permanent
fixed sand bypassing system for the Tweed River
entrance.
In 1999, 26 years after the original nourishment of
the northern beaches, 1.1M m3 of sand was
pumped from the Broadwater onto the Northern
Gold Coast beaches by a local CSD. The dredging
widened the eroded beaches and created wider
navigation channels required by the increased
boating activity resulting from the training and
bypassing of the Nerang River entrance. This
dredging was a joint Qld Transport Dept. / GCCC
project using a local medium sized cutter suction
dredger pumping up to about 5km using boosters
depositing onto the beaches. The cost of this was
about $6/m3 compared to about $1/m3 in 1974. A
further 100,000m3 was provided at no direct cost
from building excavations. This nourishment work
was in conjunction with the Narrowneck reef
construction using a local split hull TSHD that filled
mega sandbags from offshore sand reserves and
placed them nearshore. The availability of a local
shallow draft split hull TSHD resulted in very low
unit rates for the reef (approx. $40/m3 [5])
2000 to 2013; The Nerang River entrance sand
bypassing continued and the Tweed River
bypassing operations using the fixed pumping
system was commenced. As well as ongoing
routine maintenance “bypass dredging of
Currumbin and Tallebudgera Creeks, an additional
370,000m3 of sand was dredged from offshore
and placed nearshore at Palm Beach in about 6m
water depth by a local shallow draft TSHD. As
these small TSHD have low mobilisation and can
deposit nearshore in the surf zone water by bottom
dumping they are more cost effective for quantities
up to about 250,000 400,000m3 than larger
TSHD with high mobilisation costs and that need to
rainbow or pump ashore.
To combat recent erosion of Surfers Paradise
beaches sand from estuary channel dredging
works was placed nearshore by small TSHD and
onshore from trucks transporting sand from
stockpiles filled by medium sized CSD. Present
investigations are considering innovative strategies
such as reefs to reduce the long term nourishment
volumes.
1990 to 2013 saw further major nourishment works
from fixed bypassing pumps, CSD, TSHD and
trucks.
3. Sand Sources
A number of sand sources are used. Sand
characteristics and grain size are generally similar
and compatible. As well as estuaries and offshore,
excess clean sand from building sites is also
placed on the dune area. Prior to 1985 this only
applied to buildings along the beachfront. In 1985
the policy was rewritten to include all excavation of
clean sand from within 500m of the seawall line.
This has provided about another 1.8 - 2Mm3 to the
dunal areas. This sand helped create wide dunes
over previously exposed boulder walls and to
buffer recent erosion.
After the dredging of the channels in the Nerang
River estuary, the Broadwater, for the Northern
Gold Coast Beach Protection Strategy, a policy
was adopted that dredging of sand from navigation
channels in estuaries should be used for beach
nourishment. This has secured another good
source of sand for nourishment only.
The offshore dredge areas along the whole
developed coastal strip have been designated and
preserved for beach nourishment only.
Volumes from the various sand sources are
summarised in Table 1.
4. Placement locations
3 deposition options have been used:
Onshore / Beach
Nearshore
Combination; profile
The early works were all onshore and this has
developed with offshore dredging to a combination
of placement locations preferred. All have different
impacts, efficiencies and cost implications.
5. Lessons and Findings
Key findings and lessons include:
The Gold Coast beaches have been
dependent on ongoing beach nourishment with
about 49Mm3 to date. Alternate strategies and
structures to increase the long term efficiency
of nourishments, such as reefs, are being
considered.
Considerable experience and expertise has
been developed by the growth of the local
dredging industry implementing beach
nourishment on the Gold Coast. The dredging
and deposition methodologies have expanded
with experience. This has resulted in
competitive dredging rates and allowed
innovations in best practice to be developed.
The practice of monitoring the behaviour of the
beaches and nourishments with accurate
regular surveys, particularly after storms, has
provided invaluable long term data and
knowledge of the behaviour of the beaches [3].
This data has been used to determine the best
methods of nourishment placement and to
develop sand bypassing systems and alternate
strategies such as reefs. The data has also
been used to accurately calibrate and validate
various numerical models.
Dredging from offshore and nearshore
deposition has proven to be an efficient
method of beach nourishment.
Adequate sand reserves in the coastal zone
are vital to ongoing nourishment works and
policies are needed to protect these resources
for future nourishment and the long term health
of Gold Coast beaches as there is competition
for sand materials for usage for other purposes
including land reclamation, land fill, habitat
enhancement, landscaping, building materials
and other purposes.
The 2 sand bypassing systems have been very
effective in maintaining the Gold Coast
beaches [1].
Table 1 Sand to Gold Coast beaches by Source
Sand Source
Approx.
Volumes 1974 to
Jun 20013
Mm3
Estuaries
6.7
14%
Offshore [excluding Tweed &
Nerang R entrances]
6.4
13%
Building sites
2
4%
Sand bypass systems
Tweed R entrance (NSW]1
Offshore by dredgers
5.1
10%
From fixed pumps on jetty
7
14%
Nerang R Seaway2
Inshore by dredgers (new
channel construction)
4.5
9%
Offshore by dredgers
(backpassing)
minor
From fixed pumps on jetty
17.1
35%
TOTAL
48.8
100%
1http://www.tweedsandbypass.nsw.gov.au/sand_delivery
2http://www.transport.qld.gov.au/Home/Projects_and_init
iatives/Projects/Gold_coast_dredging_initiatives/
6. References
[1] Acworth, C. and Lawson, S. (2011) The Tweed
River Entrance Sand Bypassing Project - Ten
Years Of Managing Operations In A Highly
Variable Coastal System. Proceedings of the
Australasian Coasts and Ports Conference 2011.
[2] Boak, L., Jackson A., McGrath J. and Brosnan M.
(2001) An overview of Gold Coast Coastal Management
1960 - 2001. Proceedings of the Australasian Coastal &
Ocean Engineering Conference 2001.
[3] Goetsch, F. and Jackson, A. (1989) Hydrographic
Survey Data Collection Methods, Accuracy and
Assessment for Design and Monitoring of Coastal
Engineering Works. Proceedings of Australasian
Conference on Coastal and Ocean Engineering 1989
[4] Jackson, A. (1989) Implementation and Monitoring of
1.5M m3 Nearshore Nourishment at Kirra / Bilinga, Gold
Coast. Proceedings of Australasian Conference on
Coastal and Ocean Engineering 1989
[5] Jackson, L.A. and Corbett, B. B, (2007) Review of
Existing Multi-Functional Artificial Reefs Proceedings of
Australasian Conference on Coastal and Ocean
Engineering 1989
[6] Smith, A.W. and Jackson, A. The Siting of Beach
Nourishment Placements Shore & Beach Journal Vol.
58, No.1, 1990
Table 2. Sand Nourishment Projects to 2012 (excluding sand bypassing systems)
Year
Location
Qty
method
B = beach
N = nearshore
m3
CSD = cutter
suction
TSHD =
Trailing suction
hopper dredge
1973/74
Palm Beach
B
Currumbin Estuary
E
250,000
CSD
1974/75
Surfers Paradise /
Narrowneck / Main Beach
B
Nerang R
Broadwater
E
1,400,000
CSD
Kirra Beach
B
Tweed R estuary
E
1,000,000
CSD
1975/76
Currumbin Spit
B
Currumbin Estuary
150,000
CSD
1976
Southport Spit
B
Nerang R
Broadwater
E
90,000
CSD
Palm Beach
B
Currumbin Estuary
E
100,000
CSD
Burleigh beach
B
Tallebudgera Crk
estuary
E
80,000
CSD
1978 - 81
Burleigh beach
B
Tallebudgera Crk
estuary
E
100,000
CSD
Palm Beach
B
Currumbin Estuary
E
300,000
CSD
1981
Palm Beach
B
Currumbin Estuary
E
325,000
CSD
1985
Nth Kirra Beach
N
Offshore
O
100,000
TSHD
Nth Kirra Beach
B
Offshore
O
215,000
TSHD
Palm Beach
N
Offshore
O
100000
TSHD
Burleigh Beach
N
Offshore
O
183000
TSHD
Burleigh Beach
B
Offshore
O
200,000
TSHD
Surfers Paradise
N
Offshore
O
142000
TSHD
Narrowneck
B
Nerang R
Broadwater
E
300,000
CSD
Palm Beach
B
Currumbin Estuary
E
90,000
CSD
1988
Kirra - Bilinga
B
Offshore
O
1,500,000
TSHD
Burleigh beach
B
Tallebudgera Crk
estuary
E
100,000
CSD
1989
Kirra
N
Tweed R entrance
O
395,000
TSHD
Kirra
B
Tweed R entrance
O
3,200,000
TSHD
1990
Burleigh beach
B
Tallebudgera Crk
estuary
E
65,000
CSD
1991
Burleigh beach
B
Tallebudgera Crk
estuary
E
56,400
CSD
1992
Burleigh beach
B
Tallebudgera Crk
estuary
E
53,000
CSD
1994
Burleigh beach
B
Tallebudgera Crk
estuary
E
60,500
CSD
1995
Burleigh beach
B
Tallebudgera Crk
estuary
E
63,000
CSD
1996
Burleigh beach
B
Tallebudgera Crk
estuary
E
63,000
CSD
1997
Palm Beach
B
Currumbin Estuary
E
50,000
CSD
Burleigh beach
B
Tallebudgera Crk
estuary
E
70,000
CSD
1998
Burleigh beach
B
Tallebudgera Crk
estuary
E
50,000
CSD
Palm Beach
B
Currumbin Estuary
E
40,000
CSD
1999
Burleigh beach
B
Tallebudgera Crk
E
92,000
CSD
estuary
1999 /
2000
Surfers Paradise /
Narrowneck / Main Beach
B
Nerang R
Broadwater
E
1,100,000
CSD
2000
Burleigh beach
B
Tallebudgera Crk
estuary
E
44,000
CSD
2001
Burleigh beach
B
Tallebudgera Crk
estuary
E
40,800
CSD
Palm Beach
B
Currumbin Estuary
E
30,000
CSD
2002
Burleigh beach
B
Tallebudgera Crk
estuary
E
38,000
CSD
2003
Burleigh beach
B
Tallebudgera Crk
estuary
E
26,000
CSD
2004
Burleigh beach
B
Tallebudgera Crk
estuary
E
16,000
CSD
Palm Beach
N
Offshore
O
145,000
TSHD
Palm Beach
B
Currumbin Estuary
E
30,000
CSD
2005
Burleigh beach
B
Tallebudgera Crk
estuary
E
22,000
CSD
Palm Beach
B
Currumbin Estuary
E
30,000
CSD
Palm Beach
N
Offshore
O
124,000
TSHD
2006
Burleigh beach
B
Tallebudgera Crk
estuary
E
29,000
CSD
Palm Beach
B
Currumbin Estuary
E
37,000
CSD
Palm Beach
N
Offshore
O
101,000
TSHD
2007
Burleigh beach
B
Tallebudgera Crk
estuary
E
19,000
CSD
Palm Beach
B
Currumbin Estuary
E
42,000
CSD
2008
Burleigh beach
B
Tallebudgera Crk
estuary
E
31,000
CSD
2009
Burleigh beach
B
Tallebudgera Crk
estuary
E
46,000
CSD
Palm Beach
B
Currumbin Estuary
E
58,000
CSD
2010
Burleigh beach
B
Tallebudgera Crk
estuary
E
28,000
CSD
Palm Beach
B
Currumbin Estuary
E
60,000
CSD
2011
Burleigh beach
B
Tallebudgera Crk
estuary
E
44,000
CSD
Palm Beach
B
Currumbin Estuary
E
56,000
CSD
2012
Surfers Paradise
N
Nerang R estuary
E
127,000
TSHD
Palm Beach
B
Currumbin Estuary
E
35,000
CSD
13,091,700
1970 -
2013
From building sites
B
BS
2,000,000
-
15,091,700
  • ... About 22Mm 3 of sand nourishment has been dredged to date, not including the sand pumped by the fixed sand bypass systems that do not add any additional sand to the active beaches. Table 1 shows the details of the sand nourishment projects up to 2013 [7]. ...
    ... Also, top-up of Narrowneck reef "control structure" is proposed for 2017. on the Gold Coast Leslie Angus Jackson and Rodger Tomlinson Table 1 Sand to Gold Coast beaches by Source Key findings and lessons regarding nourishment [7] include: ...