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Preparation of a Coastal Zone Management Plan in Sydney Harbour – the Mosman experience Presentation to COPEP Seminar by Peter Horton 20 August 2012
Preparation of a Coastal Zone Management Plan in Sydney Harbour – the Mosman experience
Presentation to COPEP Seminar by Peter Horton
20 August 2012
Haskoning Australia Presentation 20 August 2012
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Mosman Council Office of Environment and Heritage JK Geotechnics ERM
Acknowledgements
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Admiral Arthur Phillip, 1788
“We got into Port Jackson in the afternoon and had the satisfaction of finding the finest harbour in the world, in which a thousand sail of the line may ride in the most perfect security”
Modified from source (Ozcoasts)
Landward margin of flood tide delta
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Main Drivers of Coastal Processes
swell waves astronomical tide and storm surge local wind waves boat waves
extremes of erosion driven by large swell waves combined
with elevated water levels (tide plus storm surge)
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Median Hs 1.5m 100 year ARI Hs about 9m (6 times larger) Median Tp 9.7s 90% of Tp between 6s and 14s 65% of waves come from S to SE octant 85% of storm waves come from S to SE octant (48% from
south alone)
Offshore Waves
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Direction 100 year ARI Hs (m) NE 4.4
ENE 6.0 E 7.0
ESE 7.3 SE 8.5
SSE 9.3 S 8.8
100 year ARI Hs Varying with Direction
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Do NOT apply the same wave height from every direction when modelling the NSW wave climate
Handy Hint 1
SW
BW
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Handy Hint 2
Pretty model colours do not mean they are realistic Understand model limitations Look at real data Models can be wrong! Really badly wrong Is there widespread misuse of numerical modelling in NSW
coastal studies?
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“Models are formalised representations of reality…They produce interesting pictures and flashy animations of coastal behaviour but they cannot claim to represent reality in all its complexity…The problem arises when the people who put the concepts into the model are different from the people who use the model. Then model concepts may be used out of context and results produced that are clearly wrong.”
Roelvink and Reniers (2012)
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About 20 year ARI Hs for 3, 6 and 12 hour durations (exceeded 7.5m for 3 hours, 7.3m for 6 hours and 6.7m for 12 hours)
Peak water level of 1.26m AHD (about 3 year ARI) Note that the NSW Office of Environment and Heritage is
the owner of the data displayed overleaf and Manly Hydraulics Laboratory collected the data
June 2012 Storm
The Spit, 6 June 2012
Edwards Beach, 6 June 2012
Edwards Beach, 6 June 2012 Copyright Bruce Terry, used with permission
Edwards Beach, 6 June 2012 Copyright Bruce Terry, used with permission
Edwards Beach, 6 June 2012 Copyright Bruce Terry, used with permission
Edwards Beach, 6 June 2012
Copyright Bruce Terry, used with permission
Edwards Beach, 6 June 2012
Balmoral Beach, 6 June 2012
Balmoral Beach, 6 June 2012
Balmoral Beach, 6 June 2012
Chinamans Beach, 6 June 2012
Chinamans Beach, 6 June 2012
Chinamans Beach, 6 June 2012
Chowder Bay, 6 June 2012
Little Sirius Cove, 6 June 2012
Fairy Bower, 6 June 2012
Fairy Bower, 6 June 2012
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Source: Foster, Gordon and Lawson (1975)
1974 Storms
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Other Processes
long period and low amplitude waves (offshore) generated by meteorological effects or tsunamis
meteorological effects eg shelf waves generated by passage of synoptic-scale
meteorological disturbances across the coast. tsunamis
eg Chilean earthquake May 1960: strong currents and damage to boats
seiching
Source of animation: http://en.wikipedia.org/wiki/Seiche
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managing risks to public safety and built assets pressures on coastal ecosystems community uses of the coastal zone
Guidelines for Preparing CZMP’s
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seawalls (toe levels, overtopping) cliff top development (geotechnical assessment) (private development versus public amenity not significant
issue)
Managing risks to public safety and built assets
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public access recreational use public amenity (what makes a place pleasant) heritage
Community Uses
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Foreshore Access
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The Spit, 1935 Source: State Records NSW
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Haskoning Australia started October 2011 17 staff 11 specialist coastal/maritime engineers 2 environmental scientists 1 Principal geotechnical engineer access to worldwide expertise in core business areas parent company Royal Haskoning merged with DHV,
another similar Dutch company, on 2 July 2012 new company is Royal HaskoningDHV, with 8,000 staff top 10 of independently owned, non-listed companies
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Questions?
