The Evolution and Environmental History of Wainono Lagoon, New Zealand A Thesis submitted in fulfilment of the requirements for the degree of Master of Science in Geography at the University of Canterbury Maki Norman Student number: 31612830 Geography Department University of Canterbury Christchurch 2016 Table of Contents Abstract ............................................................................................................................................ i Glossary of key Māori Terms ........................................................................................................ iii Acknowledgements ........................................................................................................................ iv Chapter 1. Introduction ............................................................................................................... 1 1.1 Thesis statement ................................................................................................................ 1 1.2 Conceptual context ........................................................................................................... 2 1.2.1 Coastal lagoons ......................................................................................................... 2 1.2.2 Coastal barriers ......................................................................................................... 4 1.2.3 Long-term lagoon stability status............................................................................ 10 1.2.4 Classification of coastal lagoons ............................................................................. 12 1.2.5 Waituna-type Lagoons ............................................................................................ 14 1.2.6 Evolutionary and environmental history of coastal lagoons ................................... 15 1.3 Previous research in the Wainono Lagoon area ............................................................. 16 1.4 Research gaps ................................................................................................................. 18 1.5 Research questions .......................................................................................................... 19 1.6 Research objectives ........................................................................................................ 19 1.7 Thesis structure ............................................................................................................... 20 Chapter 2. Study area................................................................................................................ 21 2.1 Introduction ..................................................................................................................... 21 2.2 Geology ........................................................................................................................... 26 2.3 Climate ............................................................................................................................ 27 2.4 Hydrology ....................................................................................................................... 28 2.5 Sediment Supply ............................................................................................................. 30 2.6 Sea level .......................................................................................................................... 30 2.7 Water quality .................................................................................................................. 33 2.8 Flora and fauna ............................................................................................................... 34 2.9 Historical and cultural significance ................................................................................ 34 2.10 Anthropogenic influences ............................................................................................... 36 2.11 Summary ......................................................................................................................... 39 Chapter 3. Methodology ........................................................................................................... 40 3.1 Introduction ..................................................................................................................... 40 3.2 Recent changes in geomorphology ................................................................................. 40 3.2.1 Bathymetric survey ................................................................................................. 42 Limitations and errors ........................................................................................................... 44 3.2.2 Barrier profile analysis ............................................................................................ 45 3.2.3 Aerial photograph analysis ..................................................................................... 46 3.3 Reconstruction of evolutionary and environmental history............................................ 48 3.3.1 Sediment cores ........................................................................................................ 48 3.3.2 Sediment core analysis ............................................................................................ 51 3.3.3 Anisotropy of Magnetic Susceptibility ................................................................... 51 3.3.4 Foraminiferal analysis ............................................................................................. 56 3.3.5 Grain size analysis .................................................................................................. 58 3.3.6 CM diagram ............................................................................................................ 59 Chapter 4. Recent changes in geomorphology at Wainono Lagoon ........................................ 61 4.1 Introduction ..................................................................................................................... 61 4.2 Lagoon bathymetry ......................................................................................................... 61 4.3 Beach barrier profile analysis ......................................................................................... 64 4.4 Aerial photograph analysis ............................................................................................. 68 4.5 Summary synthesis ......................................................................................................... 71 Chapter 5. Reconstruction of evolutionary and environmental history of Wainono Lagoon... 73 5.1 Introduction ..................................................................................................................... 73 5.2 Stratigraphy and sediment characteristics ...................................................................... 74 5.3 Anisotropy of Magnetic Susceptibility and grain size .................................................... 76 5.4 CM diagram .................................................................................................................... 80 5.5 Foraminiferal analysis .................................................................................................... 81 5.6 Summary synthesis ......................................................................................................... 82 Chapter 6. Discussion ............................................................................................................... 87 6.1 Introduction ..................................................................................................................... 87 6.2 The evolution and environmental history of Wainono Lagoon ...................................... 87 6.3 Recent trends .................................................................................................................. 91 6.4 High energy events ......................................................................................................... 94 6.4.1 Tsunami deposit ...................................................................................................... 96 6.5 Lagoon system ................................................................................................................ 99 6.6 Long-term stability status ............................................................................................. 101 6.7 Management ................................................................................................................. 106 6.7.1 Management framework ....................................................................................... 108 6.7.2 Short to medium-term management strategy ........................................................ 109 6.7.3 Long-term management strategy .......................................................................... 110 6.8 Summary ....................................................................................................................... 112 Chapter 7. Conclusion ............................................................................................................ 116 7.1 Thesis findings .............................................................................................................. 116 7.2 Evaluation of this research ............................................................................................ 117 7.3