Civil Defence and Emergency Management Group Committee Meeting Held on 30/08/2017

Auckland Tsunami Community Exposure Analysis R.J. Woods A. E. Lewis GNS Science Consultancy Report 2017/74 May 2017 DISCLAIMER This report has been prepared by the Institute of Geological and Nuclear Sciences Limited (GNS Science) exclusively for and under contract to Auckland Council. Unless otherwise agreed in writing by GNS Science, GNS Science accepts no responsibility for any use of or reliance on any contents of this report by any person other than Auckland Council and shall not be liable to any person other than Auckland Council, on any ground, for any loss, damage or expense arising from such use or reliance. Use of Data: Date that GNS Science can use associated data: April 2017 BIBLIOGRAPHIC REFERENCE Woods, R.J.; Lewis, A. E., 2017. Auckland Tsunami Community Exposure Analysis, GNS Science consultancy report 2017/74. 48 p. Project Number 470W1369 Confidential 2017 CONTENTS EXECUTIVE SUMMARY ............................................................................................. IV 1.0 INTRODUCTION ...............................................................................................1 2.0 SCENARIOS .....................................................................................................2 2.1.1 Day and Night Scenarios ......................................................................... 2 2.1.2 Fine, Summer Day Scenario ................................................................... 2 2.1.3 Tsunami Inundation Scenario .................................................................. 2 3.0 METHODOLOGY .............................................................................................. 5 3.1 IDENTIFICATION OF COMMUNITIES TO BE ASSESSED ................................... 6 4.0 RESULTS ..........................................................................................................9 4.1 LIMITATIONS OF MODELLED SCENARIOS .................................................. 10 5.0 DISCUSSION...................................................................................................11 6.0 ACKNOWLEDGEMENTS ................................................................................ 12 7.0 REFERENCES ................................................................................................13 FIGURES Figure 2.1 Auckland red and orange tsunami evacuation extents used in the exposure assessment. ..................................................................................................................... 4 Figure 3.1 Example showing building locations used in the occupancy model. ................................. 5 Figure 3.2 Figure showing the location of beach polygons (yellow lines) used to attribute populations for the daytime beach occupancy scenario. ..................................................................... 7 Figure 3.3 Figure depicting the extent of the Auckland Harbourside, Auckland Central West and Auckland Central East community outer limits. ................................................................ 8 TABLES Table 3.1 Beach class criteria used for the beach occupancy scenario. .......................................... 6 Table 4.1 The top twenty ranked exposed communities to tsunami in Auckland’s orange and red tsunami evacuation zones for the fine, summer day scenario. ......................................... 9 GNS Science Consultancy Report 2017/74 i Confidential 2017 APPENDICES A1.0 APPENDIX 1: SUMMARY OF RESULTS RANKED BY HIGHEST EXPOSURE .....................................................................................................15 A2.0 APPENDIX 2: INDICATIVE MAPS SHOWING LOCATIONS OF COMMUNITIES USED IN THE EXPOSURE ASSESSMENT .................................................... 21 A3.0 APPENDIX 3: DETAILED RANKED EXPOSURE RESULTS FOR COMMUNITES THAT INTERSECT THE ORANGE AND RED TSUNAMI EVACUATION ZONES FOR THE FINE, SUMMERS DAY SCENARIO........... 41 APPENDIX FIGURES Figure A2.1 Map of communities for Auckland’s north-eastern coast including Kawau Island. Blue lines indicate community boundaries. ..................................................................................... 21 Figure A2.2 Map of communities for Auckland’s north-eastern coast including Whangaparaoa Peninsula. Blue lines indicate community boundaries. ................................................... 22 Figure A2.3 Map of communities for Auckland’s North Shore. Blue lines indicate community boundaries. ..................................................................................................................... 23 Figure A2.4 Map of communities for Auckland’s northern Waitematā Harbour and Devonport. Blue lines indicate community boundaries. ............................................................................. 24 Figure A2.5 Map of communities for Waiheke Island. Blue lines indicate community boundaries. .... 25 Figure A2.6 Map of communities for the northern extent of the Waitematā Harbour. Blue lines indicate community boundaries. .................................................................................................. 26 Figure A2.7 Map of communities for the southern extent of the Waitematā Harbour. Blue lines indicate community boundaries. .................................................................................................. 27 Figure A2.8 Map of communities for Ōrākei and western Tamāki Strait. Blue lines indicate community boundaries. ..................................................................................................................... 28 Figure A2.9 Map of communities for southern Tamāki Strait. Blue lines indicate community boundaries. ....................................................................................................................................... 29 Figure A2.10 Map of communities for eastern Tamāki Strait and Howick. Blue lines indicate community boundaries. ..................................................................................................................... 30 Figure A2.11 Map of communities for Beachlands and Clevedon. Blue lines indicate community boundaries. ..................................................................................................................... 31 Figure A2.12 Map of communities for Kawakawa Bay and Orere Point. Blue lines indicate community boundaries. ..................................................................................................................... 32 Figure A2.13 Map of communities for Great Barrier Island. Blue lines indicate community boundaries. ..................................................................................................................... 33 Figure A2.14 Map of communities for south Kaipara Harbour and northern west coast. Blue lines indicate community boundaries. ..................................................................................... 34 Figure A2.15 Map of communities for Auckland’s west coast, north of the Manukau Harbour. Blue lines indicate community boundaries. ..................................................................................... 35 Figure A2.16 Map of communities for the northern Manukau Harbour. Blue lines indicate community boundaries. ..................................................................................................................... 36 Figure A2.17 Map of communities for the north-eastern Manukau Harbour. Blue lines indicate community boundaries. .................................................................................................. 37 ii GNS Science Consultancy Report 2017/74 Confidential 2017 Figure A2.18 Map of communities for the south-eastern Manukau Harbour. Blue lines indicate community boundaries. .................................................................................................. 38 Figure A2.19 Map of communities for the southern Manukau Harbour. Blue lines indicate community boundaries. ..................................................................................................................... 39 Figure A2.20 Map of communities for the Awhitu Peninsula. Blue lines indicate community boundaries. ..................................................................................................................... 40 APPENDIX TABLES Table A3.1 Ranked exposure results for each Auckland community, by Local Board Area, that intersect the orange and red tsunami evacuation zones for the fine, summers day scenario. ....................................................................................................................................... 41 GNS Science Consultancy Report 2017/74 iii Confidential 2017 EXECUTIVE SUMMARY Three scenarios, day, night and fine summers day, have been modelled to identify which Auckland communities have the greatest population exposure in the region’s orange and red tsunami evacuation areas. We consider that a worst-case exposure scenario would occur when peak tsunami waves coincide with a fine, summers day and have adopted this as the selected scenario to inform the prioritisation of communities. Based on the modelled scenario, the community with the highest exposure is Orewa with 6,521 people within the evacuation areas modelled (Appendix 1). Orewa is substantially higher than other communities and is followed by Browns Bay with 3,597 people exposed. There is a total of 22,913 exposed in the top ten ranked communities and 31,798 people exposed in the top twenty. For all 217 communities that are exposed, there is a total of

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