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Coastal Damage and Coastal Protection in NSW
James Carley
Senior Coastal EngineerWater Research Laboratory
University of New South Wales
Indigenous coastal engineering
Aboriginal fish traps Arrawarra NSW, circa 1000 ADAlso at Point Plomer, (near Crescent Head)
Chronology: Pre 1900• Circa 1000 AD: Rock fish traps were constructed at Arrawarra near Coffs
Harbour by indigenous inhabitants.• 1818-1846: “Macquarie Pier” at Hunter River mouth, Newcastle – a
breakwater/training wall.• 1854: Australia’s first reported breakwater was constructed at Port Elliot
(SA), with a paper on this structure presented to the Institution of Civil Engineers in London in 1858 – the first for an Australian civil engineering project (Gourlay, 2000).
• 1877 and 1885: Visit to Australia by Sir John Coode, engineer in chief for the British Admiralty.
• 1890s: First seawalls commenced on Sydney beaches (eg Manly).• 1890 to 1910: Construction of numerous breakwaters/training walls on
the NSW coast.
Coffs Harbour (1914)
First stone breakwater 1914 (SLNSW)
Coffs Harbour (1916)There are now approximately 70 breakwaters (/training walls) in NSWThe north coast railway in 1910s reduced the reliance on coastal shipping
Manly 1870s
MANLY 1870s (ENGRAVING)
Manly 1895
Manly 1912
MANLY, MAY 1913
Newcastle Beach c1900
Chronology: 1900s 1938: The work of Spanish engineer Iribarren (1938), “A formula for the
Calculation of Rock-Fill Dykes” published in Spanish, which was translated to English by the US Beach Erosion Board in 1949. This related the size of rock armour required to the incident wave height.
1953: The work of Hudson (1953), “Wave Forces on Breakwaters”. This related the size of rock armour required to the incident wave height.
1957: US Army Corps of Engineers/ US Beach Erosion Board “Shore Protection, Planning and Design, Technical Report Number 4”, with revised editions in 1957, 1961 and 1966.
1973: Publication of the US Army Corps of Engineers “Shore Protection Manual”, with revisions in 1975, 1977 and 1984.
1984: BS 6349 – 1984, “British Code of Practice for Maritime Structures”. 1990: First IPCC report on climate change. 1991: Publication of the CIRIA Rock Manual, which was revised in 2007. 1998: Oliver et al (1998), “Condition and Performance Rating Procedures
for Rubble Breakwaters and Jetties”.
Sydney’s sea defences (Gordon, 1989)
SYDNEY’S 23 km of open coast sandy foreshore• Seawalls 5.6 km• Rubble revetments 1.4 km• Dunes (artificial) 13.5 km• Featureless 2.6 km
• Most seawalls built 1880s to 1930s• Typical seawall toe level +2 m AHD• Toe level range 0.0 to 4.7 m AHD• Crest level range 2 to 7 m AHD
Seabee seawall, Cronulla (constructed 1980s)
Sandstone seawall and promenade - Manly
Stockton
Groynes and NourishmentLady Robinsons Beach
Documented damage and failures• CIRIA (1991) found that 36% of seawall failures (1980s) in the UK
were due directly to erosion of the toe and a further 14% were partly due to it (50% in total)
• Blumberg and Rhodes (1995), PBP (1995) identified nine episodes of damage to portions of the Manly seawall over 108 years – once every 12 years on average (typical ~200 m)
• Blain Bremner Williams (1985): • >40 NSW houses lost to coastal hazards in last 100 yrs.• Emergency management has saved more than 200
structures.
• Many structures have been removed from active zone.
North Steyne, Manly 1950
Belongil, Byron Bay13/07/1972
SEPTEMBER 1977
c1999
2001
Freshwater SLSC 1974Near miss for surf club - Sewer lines lost
Bilgola 1974
Sheltering Palms/North Beach
1977:17 houses abandoned
19761975
Beachfront house collapse Wamberal 1978
Dee Why 1998
Old Bar 2008 - 2009
COFFS HARBOUR MAY 9:30 am 24 May 1999
Northern breakwater, Coffs Harbour
Fairy Bower, Manly 27/06/2003
Chronology: 2000s
Numerous PIANC synthesis documents. 2006: Publication of “The Coastal Engineering Manual” coastal
structures chapter. 2007: ISO 21650:2007, “Actions from waves and currents on coastal
structures”, from the International Standards Organisation. 2007: EurOtop overtopping manual
Upgrade of toe of historic seawalls. Rebuilding of damaged structures. Temporary and trial structures from sand filled geotextiles. (Outside of NSW) Sand as protection.
Upgrade of toe
Cronulla - Damaged gabions (14/08/1986) and repair (2008)
Upgrade of toe: South Curl Curl
August 1976
July 2002
South Curl Curl, 2006
North Steyne, Manly upgrade of toe
1974
2010
Replacement: Dee Why (1998 – 2000s)
Collaroy-Narrabeen 1920 (early “geobags”)
Stockton SLSC: First modern geobag structure NSW
1996 1999
20012009
Temporary groynes and seawallMaroochydore QLD early 2000s
Trial geocontainer offshore breakwater (early 2000s SA)
Kirra 1936 and 2004
With sand bypassing/nourishment
Summary and chronology
• Low impact pre colonial structures (eg fish traps).• Breakwaters, training walls and ports.• Seawalls for promenades.• Hard seawalls for protection.• Repairs or replacement of old seawalls.• Temporary and trial geotextile structures.• Sand as protection.
Discussion