Physical coastal environment of Otago Harbour and offshore: assessment of effects of proposed dredging by Port Otago Ltd Prepared for Port Otago Ltd Martin Single (Shore Processes and Management Ltd) Rob Bell (NIWA) Peter McComb (MetOcean Solutions Ltd) 12 March 2010 Shore Processes and Management Ltd Contact Details: 1/15a Lothian St Christchurch, New Zealand Phone: (03) 364 2987 ext. 7926 or (03) 351 4041 or (021) 790797 E-mail:
[email protected] or
[email protected] Shore Processes and Management Ltd 1 Contents 1. Introduction 7 1.1 Background 7 1.2 1.2 Project Next Generation 8 1.2.1 Description of the proposed activity 8 1.2.2 Initial consideration of possible effects of the activity on the physical coastal environment 10 1.3 Scope of this report 12 2. The Physical Coastal Environment of Otago Harbour and Blueskin Bay 13 2.1 General geography of the area 13 2.2 Regional Geology and Quaternary history 14 2.2.1 Regional setting 14 2.2.2 Seabed sediments 16 2.3 Otago Roads 18 2.3.1 Wave Environment 18 2.3.2 Ocean and Tidal Currents 24 2.3.3 Bathymetry 25 2.3.4 Sediment Characteristics 27 2.3.5 Sediment Transport Paths 29 2.3.6 Shores 31 2.3.7 Human Activities 32 2.4 Otago Harbour 33 2.4.1 Geology 33 2.4.2 Sediments in the Lower Harbour 34 2.4.3 Hydrodynamics 38 2.4.4 Human modifications 39 2.4.5 Te Rauone Beach 39 2.4.6 Shelly Beach 40 3.