NIWA CLIENT REPORT No: HAM2015-079 Report Date: March 2016 NIWA Project: WIA15301
Total Page：16
File Type：pdf, Size：1020Kb
Technical Report 15 National Institute of Water & Atmospheric Research Ltd (NIWA) – Coastal Processes Assessment Wellington International Airport Runway Extension Coastal Processes Assessment Prepared for Wellington International Airport Ltd March 2016 Prepared by: R.G. Bell For any information regarding this report please contact: Rob Bell Programme Leader: Hazards & Risk Coastal & Estuarine Processes +64-7-856 1742 [email protected] National Institute of Water & Atmospheric Research Ltd PO Box 11115 Hamilton 3251 Phone +64 7 856 7026 NIWA CLIENT REPORT No: HAM2015-079 Report date: March 2016 NIWA Project: WIA15301 Quality Assurance Statement Reviewed by: Craig Stevens Formatting checked by: Alison Bartley Approved for release by: Andrew Laing Image of Wellington International Airport and Lyall Bay in southerly sea/swell on 20 July 2015. North is due left of image. [Source: DigitalGlobe/Google Earth] © All rights reserved. This publication may not be reproduced or copied in any form without the permission of the copyright owner(s). Such permission is only to be given in accordance with the terms of the client’s contract with NIWA. This copyright extends to all forms of copying and any storage of material in any kind of information retrieval system. Whilst NIWA has used all reasonable endeavours to ensure that the information contained in this document is accurate, NIWA does not give any express or implied warranty as to the completeness of the information contained herein, or that it will be suitable for any purpose(s) other than those specifically contemplated during the Project or agreed by NIWA and the Client. Contents Executive summary ............................................................................................................. 8 1 Background ............................................................................................................. 17 2 Description of the Project ........................................................................................ 19 3 Assessment methodology ........................................................................................ 21 3.1 Introduction ............................................................................................................ 21 3.2 Desk-top analysis .................................................................................................... 22 3.3 Field surveys ........................................................................................................... 24 3.4 Modelling approach: coastal physical processes .................................................... 30 3.5 Assessment of effects criteria: policies/plans/statutes .......................................... 35 4 Existing environment ............................................................................................... 39 4.1 Coastal and geomorphic setting ............................................................................. 39 4.2 Coastal geology, sediment processes and characteristics ...................................... 42 4.3 Marine discharges and water/sediment quality ..................................................... 49 4.4 Winds ...................................................................................................................... 52 4.5 Hydrodynamic and wave processes for existing environment ............................... 54 5 Effects Assessment: Operation of Project ................................................................. 67 5.1 Description of operational effects .......................................................................... 67 5.2 Assessment of operational effects ......................................................................... 68 5.3 Relevant assessments against statutory plans/policies or guidelines .................... 92 6 Effects assessment: Construction activities ............................................................... 94 6.1 Description of construction effects ........................................................................ 94 6.2 Assessment of construction effects ........................................................................ 97 6.3 Assessment against statutory plans/policies or technical criteria and guidelines 111 7 Mitigation and monitoring ..................................................................................... 114 7.1 Overview of effects on coastal physical processes ............................................... 114 7.2 Mitigation or avoidance measures ....................................................................... 116 7.3 Suggested coastal monitoring conditions ............................................................. 116 8 Acknowledgements ............................................................................................... 118 9 Glossary of abbreviations and terms ...................................................................... 119 Wellington International Airport Runway Extension: Coastal Processes 10 References ............................................................................................................. 121 Tables Table 3-1: Locations (WGS-84) and 2014 deployment information for the Lyall Bay instruments. 28 Table 4-1: Statistics for the distribution of measured SSC (mg/L) at the optical mooring in outer Lyall Bay. 51 Table 5-1: Change in predicted wave heights locally at site P1 near The Corner as a result of the runway extension. 74 Table 5-2: Change in predicted wave heights locally at site P4 in the centre of inner Lyall Bay as a result of the runway extension. 74 Table 6-1: Maximum predicted SSC above background levels after reasonable mixing at ~150 m for discharges at D1–D3 and sediment-discharge rates of 1 and 2 kg/s. 100 Figures Figure 2-1: General layout for the proposed 350 m south runway extension into Lyall Bay to develop a 2300 m Take Off Runway Available (TORA). 19 Figure 3-1: Sea-bed sediment sampling sites in Lyall Bay, Wellington. Contaminant sampling sites were 1, 3, 5, 8, 10, 11 and 12. 26 Figure 3-2: Extent of Lyall Bay infill bathymetry survey (black dashed line) shown against grey area collected from previous surveys. 27 Figure 3-3: Site map showing oceanographic instrument locations overlying the seabed bathymetry to WVD-53. 29 Figure 3-4: Delft3D-WAVE model grid (red) of south Wellington coast superimposed on top of the Delft3D-FLOW model grid (black) that also includes Wellington Harbour. 31 Figure 3-5: ARTEMIS finite-element model grid resolution in the area around the runway extension (left) existing runway; (right) proposed runway reclamation. 33 Figure 3-6: ARTEMIS model predicted surface water level as a result of a 1.5 m wave at the Cook Strait boundary with a wave period of 12 seconds (LEFT). Google Earth image of Lyall Bay taken on 24 July 2014 for a wave height of 1–1.5 m and a period ~10 seconds (RIGHT). 34 Figure 3-7: Areas of Conservation Value in Lyall Bay area (Tarakena Bay and Tauputeranga Island) in the Regional Coastal Plan. 36 Figure 4-1: Aerial photograph looking north on completion of the airport construction (21 Jan 1959). 40 Figure 4-2: Geomorphic features in Lyall Bay incl. the 1941 shoreline. 41 Figure 4-3: Multi-beam bathymetric data at 0.5 m resolution off the existing runway in Lyall Bay obtained by NIWA (Mackay and Mitchell, 2014). 42 Figure 4-4: Surface sea-bed sediments of Lyall Bay and Wellington south coast (from Arron & Lewis 1993). 43 Figure 4-5: Sand cover (cm) and the edge of bedrock estimated from an early geophysical survey of eastern Lyall Bay in 1971. 44 Wellington International Airport Runway Extension: Coastal Processes Figure 4-6: Historic bathymetric changes in Lyall Bay. 45 Figure 4-7: Aerial photograph of Moa Point beach showing the beach slope profile locations (transects #1-12). 47 Figure 4-8: (Right): Western end of Moa Point beach with coastal cliffs at top right; (Left): Central area of exposed rock dividing the beach into two shallow- indented coves, looking along the cuspated beach from the southern/ eastern cove. 48 Figure 4-9: Time series of suspended-sediment concentration (SSC) from the upper (8 m) and lower sensors (16 m) and significant wave height (orange) from the optical mooring in outer Lyall Bay (4-Sept to 9-Oct 2014). 51 Figure 4-10: Wind roses for the Wellington area. 53 Figure 4-11: Wind rose derived from hourly records of wind speed and direction at Wellington Airport from 1962–2004. 54 Figure 4-12: Present-day tide marks at Wellington relative to WVD-53. 55 Figure 4-13: Change in annual mean sea level at the 4 main ports of NZ since 1900. 56 Figure 4-14: Alignment of the as-built Lyall Bay outfall (white line) and sites for the Baring Head NIWA wave buoy and a recording current meter (RCM) in Lyall Bay in September 1989. 58 Figure 4-15: Lyall Bay and Moa Point circulation zones during an ebb tide (top) and a flood tide (bottom). 59 Figure 4-16: Wave refraction and diffraction patterns during a southerly-swell event on 29 April 2015. 60 Figure 4-17: Surfing waves at The Corner viewed from the stormwater outlet adjacent to the eastern carpark (30 June 2015). 61 Figure 4-18: Significant wave height (Hs) vs mean zero-crossing wave period (Tz) distribution as a % of the entire 15-year Waverider buoy record off Baring Head. 62 Figure 4-19: Hs distributions (top) full distribution (in total days per year, i.e., number of 30 minute estimates in each 0.25 m Hs bins divided by 48, with a semi-log10 scale) and (bottom) partial cumulative distribution (proportion) showing