Technical Report 2005/24 July 2005 I L Turner by COLLAROY
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COLLAROY-NARRABEEN COASTAL IMAGING SYSTEM REPORT 1 SYSTEM DESCRIPTION, ANALYSIS OF SHORELINE VARIABILITY AND EROSION/ACCRETION TRENDS: JULY 2004 - JUNE 2005 by I L Turner Technical Report 2005/24 July 2005 THE UNIVERSITY OF NEW SOUTH WALES SCHOOL OF CIVIL AND ENVIRONMENTAL ENGINEERING WATER RESEARCH LABORATORY COLLAROY-NARRABEEN COASTAL IMAGING SYSTEM REPORT 1 SYSTEM DESCRIPTION, ANALYSIS OF SHORELINE VARIABILITY AND EROSION/ACCRETION TRENDS: JULY 2004 – JUNE 2005 WRL Technical Report 2005/24 July 2005 by I L Turner Water Research Laboratory School of Civil and Environmental Engineering Technical Report No 2005/24 University of New South Wales ABN 57 195 873 179 Report Status Final King Street Date of Issue July 2005 Manly Vale NSW 2093 Australia Telephone: +61 (2) 9949 4488 WRL Project No. 02092.01 Facsimile: +61 (2) 9949 4188 Project Manager Ian L Turner Title Collaroy-Narrabeen Coast Coastal Imaging System - Report 1: System Description, Analysis of Shoreline Variability and Erosion/Accretion Trends: July 2004 – June 2005 Author(s) Ian L Turner Client Name Warringah Council Client Address Civic Centre, 725 Pittwater Road, Dee Why NSW 2099 Client Contact Daylan Cameron – Catchment Management Team Client Reference The work reported herein was carried out by the Water Research Laboratory, School of Civil and Environmental Engineering, University of New South Wales, acting on behalf of the client. Information published in this report is available for general release only by permission of the Director, Water Research Laboratory, and the client. WRL TECHNICAL REPORT 2005/24 CONTENTS 1. INTRODUCTION 1-1 1.1 General 1-1 1.2 Report Outline 1-2 2. BACKGROUND 2-1 2.1 Environmental Setting 2-1 2.2 Study Area 2-1 3. DESCRIPTION OF THE COLLAROY-NARRABEEN COASTAL IMAGING SYSTEM 3-1 3.1 What is Coastal Imaging? 3-1 3.2 The Difference between Coastal Imaging and a 'surfcam' 3-1 3.3 The ARGUS Coastal Imaging System 3-2 3.4 Design of Optimum Camera Layout for Collaroy-Narrabeen 3-2 3.5 Installation 3-3 3.6 Calibration 3-3 3.6.1 Lens/Camera Calibration 3-4 3.6.2 Ground Control Point (GCP) Survey 3-5 4. IMAGE TYPES AND IMAGE PROCESSING TECHNIQUES 4-1 4.1 Image Types 4-1 4.1.1 Snap-Shot 'snap' Images 4-1 4.1.2 Time-Exposure 'timex' Images 4-1 4.1.3 Variance 'var' Images 4-2 4.1.4 Day Time-Exposure 'daytimex' Images 4-2 4.2 Basic Image Processing – Merge and Rectification 4-2 4.3 Shoreline Detection and Analysis 4-3 4.3.1 Overview of the ‘PIC’ shoreline identification technique 4-3 4.3.2 Standardised Procedure for Shoreline Mapping 4-4 5. COASTAL IMAGING WEB SITE 5-1 5.1 Coastal Imaging Home Page 5-1 5.2 Image Archive 5-1 5.3 On-Line ‘Beach Analysis System’ 5-2 6. MORPHODYNAMIC DESCRIPTION OF COLLAROY-NARRABEEN: JULY 2004 – JUNE 2005 6-1 6.1 A Morphodynamic Classification of Beaches 6-1 6.2 Morphodynamic Interpretation of Daily Images 6-2 6.2.1 July 2004 6-3 6.2.2 August 2004 6-4 6.2.3 September 2004 6-4 6.2.4 October 2004 6-4 6.2.5 November 2004 6-5 6.2.6 December 2004 6-6 6.2.7 January 2005 6-6 6.2.8 February 2005 6-7 6.2.9 March 2005 6-7 6.2.10 April 2005 6-8 - i - WRL TECHNICAL REPORT 2005/24 6.2.11 May 2005 6-8 6.2.12 June 2005 6-8 6.3 Visual Assessment of Net Beach Width Changes (July 2004 – June 2005) 6-9 7. QUANTITATIVE ANALYSIS OF SHORELINE CHANGES: JULY 2004 – JUNE 2005 7-1 7.1 Weekly Shorelines 7-1 7.2 Shoreline Variability – Mean, Maximum, Minimum, Standard Deviation 7-2 7.3 Time-Series of Beach Widths at Control Transects 7-3 7.4 Future reporting 7-4 8. ANALYSIS OF EROSION-ACCRETION TRENDS 8-1 8.1 Methodology 8-1 8.2 Monthly Beachface Bathymetric Mapping 8-1 8.3 Monthly Erosion-Accretion Trends 8-2 8.4 Net Erosion-Accretion Trends: June 2004 - November 2004 8-4 9. SUMMARY AND CONCLUSIONS 9-1 9.1 Qualitative Visual Assessment 9-1 9.2 Shoreline Variability and Beach Width Analysis 9-2 9.3 Erosion/Accretion Trends 9-3 10. ACKNOWLEDGEMENTS 10-1 11. REFERENCES 11-1 APPENDIX A – WEEK-TO-A-PAGE: JULY 2004-JUNE 2005 APPENDIX B – MONTHLY WAVE CLIMATE SUMMARIES: JULY 2004–JUNE 2005 APPENDIX C – Aarninkhof et al., (2003). Coastal Engineering, Vol.49(4), p.275-289. - ii - WRL TECHNICAL REPORT 2005/24 LIST OF FIGURES 2.1 Locality 2.2 Collaroy - Narrabeen Embayment, NSW 2.3 Precinct 3 2.4 Coastal Erosion – 1950’s , 1970’s and 2002 3.1 Schematic of an ARGUS Coastal Imaging System 3.2 Design of Optimum Five-Camera Layout 3.3 Location of Coastal Imaging System – Flight Deck Building 3.4 Cameras Mounted at an Elevation of Approximately 50 m 3.5 Calibration of Intrinsic (CCD-Lens) Camera Model Parameters 3.6 GCP Survey (Composite Images - Camera 1 and Camera 5) 4.1 Snap-Shot, Time-Exposure and Variance Image Types (29/06/05) 4.2 Pan and Plan View Images: Five-Camera Merge/Rectification (29/06/05) 4.3 Identification of ‘Shoreline’ Feature from Colour Images 4.4 Standardised Shoreline Mapping Procedure 5.1 Coastal Imaging Web Site – Home Page 5.2 Coastal Imaging System Web Site – Image Archive 5.3 On-Line Beach Analysis System – ‘Week-to-a-Page’ 5.4 On-Line Beach Analysis System – ‘Beach Width Analysis’ 6.1 Morphodynamic Beach State Model (after Wright and Short, 1983) 6.2 Snap Images from Camera 1 (South): 15/07/04 and 29/06/05 6.3 Snap Images from Camera 5 (North): 15/07/04 and 29/06/05 7.1 Weekly Shorelines: July 2004 – June 2005 7.2 Weekly Beach Width: July 2004 – June 2005 7.3 Statistical Summary of Beach Width Changes: July 2004 – June 2005 7.4 Time-Series of Beach Width: July 2004 – June 2005 7.5 On-Line Beach Width Analysis: June 2005 8.1 Definition Sketch - Intertidal Bathymetry from Hourly Waterlines 8.2 Beachface Mapping – July, August 2004 8.3 Beachface Mapping – September, October 2004 8.4 Beachface Mapping – November, December 2004 8.5 Beachface Mapping – January, February 2005 8.6 Beachface Mapping – March, April 2005 8.7 Beachface Mapping – May, June 2005 8.8 Monthly Erosion/Accretion: July - October 2004 8.9 Monthly Erosion/Accretion: October 2004 – January 2005 8.10 Monthly Erosion/Accretion: January – April 2005 8.11 Monthly Erosion/Accretion: April – June 2005 8.12 Net Erosion/Accretion: July 2004 – June 2005 - iii - WRL TECHNICAL REPORT 2005/24 1-1. 1. INTRODUCTION This report was prepared by the Water Research Laboratory (WRL) of the University of New South Wales for Warringah Council. It is the first in a series of annual data reports, to describe, quantify and analyse the regional-scale coastline variability and erosion/accretion trends that occur at Collaroy-Narrabeen Beaches. This annual summary supplements the on-line and ‘real-time’ monitoring program information that is available to Council and the community via the world-wide web (refer Section 5). It is intended that the growing database describe herein, of qualitative and quantitative coastal monitoring information, will inform and enhance the current and future management of the Collaroy-Narrabeen embayment. 1.1 General In July of 2004, an ARGUS coastal imaging system was installed at the Collaroy- Narrabeen site for an initial period of three years. This leading-edge technology was selected by Warringah Council to provide regional-scale, continuous and long-term monitoring of this ‘high value’ coastal embayment. It is the ability to provide quantitative as well as qualitative information that distinguishes the ARGUS coastal imaging system from conventional 'webcam' or 'surfcam' technology. Collaroy-Narrabeen is the first of a growing number of coastal management sites in New South Wales that now utilise coastal imaging technology and associated digital image techniques to monitor regional-scale coastal response to natural and engineered coastal impacts. Coastal imaging stations have been operating at coastal management sites in Australia since the first site was installed at the northern Gold Coast in 1999, and at the present time there are a total of 9 stations operating throughout Queensland and New South Wales (Turner et al., 2005). Electronic copies of this and all future monitoring reports (as they are produced) are made available for public viewing and download in PDF format at: Æ www.wrl.unsw.edu.au/coastalimaging/narrabn (link: monitoring reports) The purpose of this first report is to describe the ARGUS system now installed at the Collaroy-Narrabeen embayment, and to present a summary of the results of shoreline WRL TECHNICAL REPORT 2005/24 1-2. change analysis and erosion/accretion analysis for the initial 12-month monitoring period July 2004 to June 2005. 1.2 Report Outline Following this introduction, Section 2 of this report provides a brief description of the Collaroy-Narrabeen embayment, and in the particular the ‘Precinct 3’ study area. Section 3 contains a description of the ARGUS coastal imaging system, including the design, installation and calibration of the system at the Collaroy-Narrabeen site. The image types that are collected on a routine basis are illustrated in Section 4, along with an overview of the digital image processing techniques used to analyse the images. More detailed description is provided of the key image analysis method that is used on a routine (weekly) basis to map the shoreline and beach width at the Precinct 3 study area.