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Auckland: A Case Study in the Regional Assessment of Long-Term Sea Level Change (4854)

John Hannah, Rob Bell and Ryan Paulik (New Zealand)
Professor John Hannah
School of Surveying
University of Otago
PO Box 56
Dunedin
9054
New Zealand
 
Corresponding author Professor John Hannah (email: john.hannah[at]otago.ac.nz, tel.: + 64 3 479 9010)
 

[ abstract ] [ paper ] [ handouts ]

Published on the web 2011-02-10
Received 2010-11-22 / Accepted 2011-02-10
This paper is one of selection of papers published for the FIG Working Week 2011 in Marrakech, Morocco and has undergone the FIG Peer Review Process.

FIG Working Week 2011
ISBN 978-87-90907-92-1 ISSN 2307-4086
http://www.fig.net/resources/proceedings/fig_proceedings/fig2011/index.htm

Abstract

Climate change has a variety of important environmental impacts, one of which is reflected in changing sea levels. Increasingly, for coastal management activities planners, engineers and surveyors need a reliable assessment of the sea level changes that can be expected over the next 100 years. While the Intergovernmental Panel on Climate Change (IPCC) has produced such assessments, they give a global picture only – a picture that may not be applicable in a regional context. This paper documents recent work undertaken in New Zealand to assess the likely sea level change out to 2100 AD at the country’s largest city, Auckland. It draws together geological data from the Holocene period, sea level data from the last 110 years, continuous GPS (cGPS) collected over the last 10 years, and future climate change projections in order to build a long-term hazard profile for sea level rise in Auckland. This hazard analysis includes an assessment of the seasonal, decadal, and inter-decadal variability in Auckland sea levels. It is perhaps the most comprehensive sea level change assessment undertaken in New Zealand to date and acts as a model for similar analyses elsewhere. It concludes that existing national planning guidelines used in New Zealand for coastal hazards and climate change which, paraphrased, state, “plan for a 0.5 m sea level rise and assess sensitivity of activity to at least a 0.80 m rise by the 2090s” are appropriate for Auckland. The paper also concludes that a low probability but upper limit to any near term sea level rise expectations (i.e., in the next 90 years) should be informed by the historical sea levels prevalent at the last the mid-Holocene climatic optimum when global temperatures were warmer than at present. At that time eustatic sea levels around New Zealand were between 0.5 m – 1.0 m higher than at present.
 
Keywords: Hydrography; Coastal Zone Management; climate change; sea level change

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