Cape Preston Services Corridor Culverts
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Appendix E Tidal Flow Monitoring GEMS 2008 GEMS GLOBAL ENVIRONMENTAL MODELLING S Y S T E M S GLOBAL ENVIRONMENTAL MAPPING S Y S T E M S GLOBAL ENVIRONMENTAL MONITORING S Y S T E M S Technical Report OCEANOGRAPHIC STUDIES FOR THE DEVELOPMENT OF THE CAPE PRESTON SERVICES CORRIDOR CAUSEWAY February 2008 GEMS GEMS CONTACT DETAILS Melbourne Office Perth Office Telephone: +61 (0)3 9712 0016 Telephone: +61 (0)8 6364 0880 PO Box 149 PO Box 1432 Warrandyte VIC 3113 Subiaco WA 6097 Dr Graeme D Hubbert Matt Eliot Head of Oceanographic Studies Coastal Engineer Mobile: +61 (0)418 36 63 36 Mobile: +61 (0)408 414 225 Email: [email protected] Email: [email protected] Steve Oliver Jason Catlin Head of Meteorological and Wave Studies Head of GIS Mapping Systems Mobile: +61 (0)408 81 8702 Mobile: +61 (0)407 048 458 Email: [email protected] Email: [email protected] Website: www.gems-aus.com ABOUT GEMS Global Environmental Modelling Systems (GEMS), a wholly owned Australian company, has expertise in the development and application of high-resolution computer models to realistically predict atmospheric and oceanographic conditions for use in riverine, coastal and oceanic settings. The GEMS team is made up of qualified and experienced physical oceanographers, meteorologists, numerical modellers and environmental scientists. GEMS is a leading developer of numerical models in Australia. It has developed a system of validated environmental models and rigorous analytical procedures that provide solutions to a variety of environmental, engineering and operational problems. DISCLAIMER This report and the work undertaken for its preparation, is presented for the use of the client. Global Environmental Modelling Systems (GEMS) warrants that the study was carried out in accordance with accepted practice and available data, but that no other warranty is made as to the accuracy of the data or results contained in the report. This GEMS report may not contain sufficient or appropriate information to meet the purpose of other potential users. GEMS, therefore, does not accept any responsibility for the use of the information in the report by other parties. Page | 2 GEMS TABLE OF CONTENTS GEMS Contact Details ............................................................................................................ 2 About GEMS........................................................................................................................... 2 Disclaimer .............................................................................................................................. 2 1 Introduction.................................................................................................................. 6 2 Tidal Flow Studies......................................................................................................... 8 2.1 Tidal Modelling............................................................................................................. 8 2.2 Sources of Bathymetry and Topography.................................................................... 10 2.3 Simulation of tidal flows under Existing Conditions................................................... 10 2.3.1 Verification of Large Scale Tidal Dynamics ......................................................... 10 2.3.2 Simulation of the Local Tidal Flows through the Causeway Region ................... 12 2.4 Area of culverts required to minimise disturbance to tidal levels............................. 12 2.5 Effects of the temporary causeway as currently designed ........................................ 15 2.6 Effects of Sea Level Rise ............................................................................................. 15 3 Storm Surge Studies ................................................................................................... 17 3.1 Existing Conditions ..................................................................................................... 19 3.1.1 Methodology....................................................................................................... 19 3.1.2 Modelling Process............................................................................................... 20 3.1.3 Description of Numerical Models ....................................................................... 21 3.1.4 Storm Surge Validation ....................................................................................... 24 3.1.5 Storm Surge Return Periods at the Causeway.................................................... 28 3.2 Effects of the temporary Causeway with culverts ..................................................... 28 3.3 Effects of the permanent Causeway with culverts..................................................... 29 3.4 Effects of sea level rise on the 1 in 100 year storm surge.......................................... 30 4 Summary of findings................................................................................................... 31 4.1 Verification of tidal/storm surge model..................................................................... 31 4.2 Existing Tidal Conditions............................................................................................. 31 4.3 Area of culverts required to minimise interference with tidal flows......................... 31 Page | 3 GEMS 4.4 Impacts of the Temporary Causeway with culverts on Tidal Flows........................... 31 4.5 The Impacts of the permanent Causeway with culverts on Tidal Flows.................... 32 4.6 The Impacts of a sea level rise of 0.5 metre on the Tidal Flow results ...................... 32 4.7 The existing 1 in 100 year storm surge event at the causeway ................................. 32 4.8 Effects of the temporary Causeway with culverts on storm surges .......................... 32 4.9 Effects of the permanent Causeway with culverts on storm surges.......................... 33 5 References.................................................................................................................. 34 TABLE OF FIGURES Figure 1.1: Plan of the proposed services corridor causeway route superimposed on high resolution (20metres) model grid showing the two creek flat crossings. ................ 7 Figure 2.1: The domain for GEMSURGE showing the location of the verification data (CM1b). ......................................................................................................................... 9 Figure 2.2: Very high resolution grid (3 metres) of proposed causeway region at high tide. ......................................................................................................................... 9 Figure 2.3: Comparison of tidal levels predicted by GEMSURGE (red) with observations (blue) from September 15 to December 31, 2006. ........................................................ 11 Figure 2.4: Comparison of tidal heights during a spring tide event before (blue) and after (red) the causeway and culverts are installed................................................................ 14 Figure 2.5: Comparison of tidal heights during a spring tide event before (blue) and after (red) the causeway and 109 m2 culverts are installed.................................................... 16 Figure 3.1: Components of sea level elevation during cyclones...................................... 18 Figure 3.2: Tracks of cyclones included in cyclone climatology in the vicinity of Cape Preston. ....................................................................................................................... 19 Figure 3.3: Flowchart of model components for determination of waves and water levels for a cyclone event. .............................................................................................. 20 Figure 3.4: Evolution of model wind field for Cyclone Orson passing close to Cape Preston, April 1989. ........................................................................................................ 22 Figure 3.5: Model wind time series for tip of Cape Preston............................................ 22 Page | 4 GEMS Figure 3.6: Tracks of cyclones Clare and Glenda. ............................................................ 24 Figure 3.7: Cape Lambert tide gauge and residual during TC Clare (courtesy WA DPI).. 25 Figure 3.8: Observed and modelled winds at Roebourne – Cyclone Clare. .................... 26 Figure 3.9: Observed winds at Roebourne during Cyclone Glenda and modeled winds for the event with radius of maximum winds set to 30 and 35 km. .................................... 26 Figure 3.10: Observed and modeled water level at Cape Lambert Jetty during Cyclone Clare ....................................................................................................................... 27 Figure 3.11: Modeled water level for Cyclone Glenda compared with tidal prediction at Cape Lambert.................................................................................................................. 27 Figure 3.12: Comparison of modeled peak water level at three locations during Glenda.27 Figure 3.13: Results for the 1 in 100 year storm surge at the southern creek crossing for the three cases studied................................................................................................... 30 Page | 5 GEMS 1 INTRODUCTION CP Mining Management Pty Ltd (CPMM) are developing the Austeel Project at Cape Preston, located some 60 km west of Dampier in North West Australia.