title: Sediment transport and tidal inlet hydraulics

authors: Black, Kerry P.

abstract: An investigation into sediment transport and tidal inlet hydraulics was initiated to ascertain the impact of a proposed timber port development at Marsden Point in Whangarei Harbour. The program progressed along two parallel pathways, i.e. (i) an expository description of the relevant harbour characteristics using field measurements and numerical modelling and (ii) a detailed investigation into the physics of sediment transport under tidal flow.

The first of these provided an understanding of the hydraulic and sediment transport characteristics of the inlet while aiming to separate cause and effect in the present harbour configuration, The numerical modelling extended this to provide predictions of future behaviour after port construction. In the tidal environment, methods to isolate the effective component of the flow velocity responsible for the transport of sediment are often inadequately substantiated being mostly derived in rivers or flumes. Accordingly, the second aspect of the program necessarily approached and extended the current state of the art with respect to sediment transport under oscillating, non-steady tidal currents in an estuary.

Bathymetric and sea bed surveys revealed that the harbour is mostly stable in an inlet receiving low inputs of sandy sediment. The entrance is sheltered from most storm wave attack by land masses offshore. Due to preferential scouring of sandy bed material, the channels are typically lined with a predominantly-stable, shell-gravel lag. Zones of deposition primarily occur in areas of tidal current neutrality.

Outside the entrance, with the added wave influences, bathymetric changes are greater. Using the experimental results in conjunction with inferences from standard tidal deltas, the changes were seen to be occurring in a closed or partially-closed sediment loop in northern Bream Bay including ebb-tidal transport around the north and east of Mair Bank, wave-induced, shoreward sediment transport over the southern segments of the ebb-tidal delta and northward longshore transport along Bream Bay Beach and through the marginal flood channel off Marsden Point.

Similar controlling transport directions occur inside the entrance with the two most dominant being an ebb-directed route from One Tree Point along the shipping channel and out of the southern side of the entrance throat. Another passes up the Snake Bank flood ramp and around the north-east flank of the flood-tidal delta. 

More than 600 vertical velocity profiles were measured in the estuary. These were examined to derive bed friction coefficients and, over megaripples, the form drag and effective components of the bed shear stress were isolated. This was applied to the determination of the sediment threshold velocity and /the transport of sandy material as bedload. New methods to ascertain the threshold and to derive the bedload transport fluxes over megaripples were presented.

Wave height measurements and sediment trapping experiments revealed that the timber port would have a very limited influence on its environment due to changes of sediment transport patterns on the inter-tidal zone at the port site. 

One and two-dimensional numerical hydrodynamic models and a 2-dimensional numerical sediment transport model were produced for the study and applied to the proposed timber port construction and dredge zone. The sediment model provides erosion and sedimentation rates in a tidal inlet.

With the sediment transport model and the 2-dimensional hydrodynamic model in a coupled mode, numerical experiments were undertaken to produce a fully-developed estuary from an initially planar bathymetry. By alternately running each model to obtain water speeds and bathymetry changes, an estuary with inter-tidal flood-tidal deltas, ebb-tidal deltas, a deep main channel, marginal flood and ebb channels and a stable ebb shield developed. The method has considerable potential for the prediction of final equilibrium bathymetry after man-made changes. 

An iterative technique was designed which utilises the sediment transport model and the water velocities provided by the hydrodynamic model. The procedure determines the percentage of sand cover at all locations throughout the model region in a stable estuary and would allow an optimisation of the minimum quantities of dumped lag material necessary to prevent scour or accretion by establishing a dynamic equilibrium over large areas of the harbour bed.

After accounting for the shell cover which restricts the transport of sediment, the maintenance dredging requirements for the initial 2 berth port development (Case A7) were small and estimated to be in the range of 10,000 m³ to 30,000 m³ per year. The impact of the port in the vicinity of the NZRC wharf is expected to be minimal with some slow sedimentation of the order of a few centimetres per year possibly occurring. In Shoal  Bay, the port should have an extremely limited impact. In the shipping channel to One Tree Point, small amounts of erosion may occur in response to an increased flow velocity (≃5%) caused by deepening of the channel in the dredge zone.

text: Sediment transport and tidal inlet hydraulics An investigation into sediment transport and tidal inlet hydraulics was initiated to ascertain the impact of a proposed timber port development at Marsden Point in Whangarei Harbour. The program progressed along two parallel pathways, i.e. (i) an expository description of the relevant harbour characteristics using field measurements and numerical modelling and (ii) a detailed investigation into the physics of sediment transport under tidal flow.

The first of these provided an understanding of the hydraulic and sediment transport characteristics of the inlet while aiming to separate cause and effect in the present harbour configuration, The numerical modelling extended this to provide predictions of future behaviour after port construction. In the tidal environment, methods to isolate the effective component of the flow velocity responsible for the transport of sediment are often inadequately substantiated being mostly derived in rivers or flumes. Accordingly, the second aspect of the program necessarily approached and extended the current state of the art with respect to sediment transport under oscillating, non-steady tidal currents in an estuary.

Bathymetric and sea bed surveys revealed that the harbour is mostly stable in an inlet receiving low inputs of sandy sediment. The entrance is sheltered from most storm wave attack by land masses offshore. Due to preferential scouring of sandy bed material, the channels are typically lined with a predominantly-stable, shell-gravel lag. Zones of deposition primarily occur in areas of tidal current neutrality.

Outside the entrance, with the added wave influences, bathymetric changes are greater. Using the experimental results in conjunction with inferences from standard tidal deltas, the changes were seen to be occurring in a closed or partially-closed sediment loop in northern Bream Bay including ebb-tidal transport around the north and east of Mair Bank, wave-induced, shoreward sediment transport over the southern segments of the ebb-tidal delta and northward longshore transport along Bream Bay Beach and through the marginal flood channel off Marsden Point.

Similar controlling transport directions occur inside the entrance with the two most dominant being an ebb-directed route from One Tree Point along the shipping channel and out of the southern side of the entrance throat. Another passes up the Snake Bank flood ramp and around the north-east flank of the flood-tidal delta. 

More than 600 vertical velocity profiles were measured in the estuary. These were examined to derive bed friction coefficients and, over megaripples, the form drag and effective components of the bed shear stress were isolated. This was applied to the determination of the sediment threshold velocity and /the transport of sandy material as bedload. New methods to ascertain the threshold and to derive the bedload transport fluxes over megaripples were presented.

Wave height measurements and sediment trapping experiments revealed that the timber port would have a very limited influence on its environment due to changes of sediment transport patterns on the inter-tidal zone at the port site. 

One and two-dimensional numerical hydrodynamic models and a 2-dimensional numerical sediment transport model were produced for the study and applied to the proposed timber port construction and dredge zone. The sediment model provides erosion and sedimentation rates in a tidal inlet.

With the sediment transport model and the 2-dimensional hydrodynamic model in a coupled mode, numerical experiments were undertaken to produce a fully-developed estuary from an initially planar bathymetry. By alternately running each model to obtain water speeds and bathymetry changes, an estuary with inter-tidal flood-tidal deltas, ebb-tidal deltas, a deep main channel, marginal flood and ebb channels and a stable ebb shield developed. The method has considerable potential for the prediction of final equilibrium bathymetry after man-made changes. 

An iterative technique was designed which utilises the sediment transport model and the water velocities provided by the hydrodynamic model. The procedure determines the percentage of sand cover at all locations throughout the model region in a stable estuary and would allow an optimisation of the minimum quantities of dumped lag material necessary to prevent scour or accretion by establishing a dynamic equilibrium over large areas of the harbour bed.

After accounting for the shell cover which restricts the transport of sediment, the maintenance dredging requirements for the initial 2 berth port development (Case A7) were small and estimated to be in the range of 10,000 m³ to 30,000 m³ per year. The impact of the port in the vicinity of the NZRC wharf is expected to be minimal with some slow sedimentation of the order of a few centimetres per year possibly occurring. In Shoal  Bay, the port should have an extremely limited impact. In the shipping channel to One Tree Point, small amounts of erosion may occur in response to an increased flow velocity (≃5%) caused by deepening of the channel in the dredge zone.

year: 1983

title: Audiovisual installation as ecological performativity: A creative research practice.

authors: Connors, Teresa Marie

subjects: Audiovisual installation as ecological performativity

abstract: Audiovisual Installation as Ecological Performativity lies in the fields of sonic arts and audiovisual practice, which experiment with developing non-linear installations from a temporally dynamic aesthetic. The project was initiated by my recent shift in artistic practice away from fixed-media audiovisual formats to non-linear procedures and by recent ecological discourses of human and nonhuman agency. The research aims to locate an ecology of practice that, rather than being autonomous and reductive, is directly affected by the specificity and proximity of connections made in practice and process on a relational level.
The submitted non-linear installations resulted from three field recording projects carried out between June 2014 and December 2015, spanning the west coast of North America from the Salton Sea in Southern California, to the northern regions of western Canada. From initial processes with practitioners from the fields of moving image, my iterative creative practice developed and applied computational methods to tease out co-creative apparatuses from the audiovisual material gathered. These techniques came to include convolution, data sonification, computer vision and improvisation as a means to explore nonlinear processes. Barry Truax, Damian Keller, R. Luke Dubois, Andrea Polli and Jean-Marc Pelletier provided useful insights to contemplate these computational processes as co-creative devices.
The work Undercurrent incorporates material gathered from the Y alakom River in British Columbia, Canada, using visual material by media artist Shannon Harris. The remaining works-Flight Variant, Cathedral and Piano at the End of a Poisoned Stream-emerged from two audiovisual collection journeys through the south-western regions of the United States with filmmaker Andrew Denton.
My research was guided by the belief that non-linear creative processes exploring co-creative devices from the agency of material can elicit different sensibilities and lines of communication, providing an alternative way in which to be in creative practice and experience the world-one that is emergent, contingent and performative. Thus my project was drawn to concepts of material agency and performativity in the writings of Karen Barad, Jane Bennett, Judith Butler, Donna Haraway, Andrew Pickering, and Timothy Morton. In addition, the philosophical provocations of Timothy Ingold, Erin Manning, Brian Massumi, Isabelle Stengers, and Thon Van Dooren were enlisted to locate my ecology of practice in a relational mode of experience that emphasized an ecological awareness.
From the position of creative research, attention to these theoretical discourses provided an opportunity to reconceptualise and ask new questions from the core of artistic practice. The result evolved into what I have come to call Ecological Performativity. This is a mode of practice that considers-in act and thought-the context and formative creative process, and the resulting artefacts, as a responsive embodiment of larger structures of phenomena. The outcome is a reorientation of my creative thinking-making procedures. The notion of creativity shifts from an anthropocentric understanding to a relational and performative ontology where the interactions between people, places and things constitute a dynamic mode of artistic practice.
Ultimately, my practice-based research is a multimodal endeavour deeply entangled in the mesh of the world: matter, materials, and modes of thinking. In line with the discussions on agency and performativity, this research considers the complex, emergent and dynamic encounters available through situated experience and experimentation. By considering the world as a network of phenomena that are fundamentally interconnected and interdependent, the result is a performative engagement and attunement with the world that functions as an aid to the imagination. Human activity is placed into a larger environmental context as it intersects with forces greater than those of human design, providing a multilayered point of creative enquiry. This, I believe, works towards an artistic philosophy that purposes the way we imagine the world and how we act in it reciprocally inform one another. As such, the concept of Ecological Performativity developed alongside the iterative creative practice.
The creative and written components of this dissertation are two expressions of the practice, process and outcome and should be considered holistically. Documentation films and the creative code accompany all resulting artefacts, and are located on the external flash drive as indicated in the Appendix.
Aspects of my research have been published internationally during the course of my research.

text: Audiovisual installation as ecological performativity: A creative research practice. Audiovisual Installation as Ecological Performativity lies in the fields of sonic arts and audiovisual practice, which experiment with developing non-linear installations from a temporally dynamic aesthetic. The project was initiated by my recent shift in artistic practice away from fixed-media audiovisual formats to non-linear procedures and by recent ecological discourses of human and nonhuman agency. The research aims to locate an ecology of practice that, rather than being autonomous and reductive, is directly affected by the specificity and proximity of connections made in practice and process on a relational level.
The submitted non-linear installations resulted from three field recording projects carried out between June 2014 and December 2015, spanning the west coast of North America from the Salton Sea in Southern California, to the northern regions of western Canada. From initial processes with practitioners from the fields of moving image, my iterative creative practice developed and applied computational methods to tease out co-creative apparatuses from the audiovisual material gathered. These techniques came to include convolution, data sonification, computer vision and improvisation as a means to explore nonlinear processes. Barry Truax, Damian Keller, R. Luke Dubois, Andrea Polli and Jean-Marc Pelletier provided useful insights to contemplate these computational processes as co-creative devices.
The work Undercurrent incorporates material gathered from the Y alakom River in British Columbia, Canada, using visual material by media artist Shannon Harris. The remaining works-Flight Variant, Cathedral and Piano at the End of a Poisoned Stream-emerged from two audiovisual collection journeys through the south-western regions of the United States with filmmaker Andrew Denton.
My research was guided by the belief that non-linear creative processes exploring co-creative devices from the agency of material can elicit different sensibilities and lines of communication, providing an alternative way in which to be in creative practice and experience the world-one that is emergent, contingent and performative. Thus my project was drawn to concepts of material agency and performativity in the writings of Karen Barad, Jane Bennett, Judith Butler, Donna Haraway, Andrew Pickering, and Timothy Morton. In addition, the philosophical provocations of Timothy Ingold, Erin Manning, Brian Massumi, Isabelle Stengers, and Thon Van Dooren were enlisted to locate my ecology of practice in a relational mode of experience that emphasized an ecological awareness.
From the position of creative research, attention to these theoretical discourses provided an opportunity to reconceptualise and ask new questions from the core of artistic practice. The result evolved into what I have come to call Ecological Performativity. This is a mode of practice that considers-in act and thought-the context and formative creative process, and the resulting artefacts, as a responsive embodiment of larger structures of phenomena. The outcome is a reorientation of my creative thinking-making procedures. The notion of creativity shifts from an anthropocentric understanding to a relational and performative ontology where the interactions between people, places and things constitute a dynamic mode of artistic practice.
Ultimately, my practice-based research is a multimodal endeavour deeply entangled in the mesh of the world: matter, materials, and modes of thinking. In line with the discussions on agency and performativity, this research considers the complex, emergent and dynamic encounters available through situated experience and experimentation. By considering the world as a network of phenomena that are fundamentally interconnected and interdependent, the result is a performative engagement and attunement with the world that functions as an aid to the imagination. Human activity is placed into a larger environmental context as it intersects with forces greater than those of human design, providing a multilayered point of creative enquiry. This, I believe, works towards an artistic philosophy that purposes the way we imagine the world and how we act in it reciprocally inform one another. As such, the concept of Ecological Performativity developed alongside the iterative creative practice.
The creative and written components of this dissertation are two expressions of the practice, process and outcome and should be considered holistically. Documentation films and the creative code accompany all resulting artefacts, and are located on the external flash drive as indicated in the Appendix.
Aspects of my research have been published internationally during the course of my research.

year: 2017

title: Using the curriculum guidelines for the teaching and learning of te reo Māori in Years 1 – 13 of New Zealand schools to create lessons for young learners

authors: Johnson, Diane

subjects: New Zealand

abstract: In 2009, The New Zealand Ministry of Education published curriculum guidelines for te reo Maori in Years 1 – 13 of English-medium New Zealand schools, that is, from age 5 upwards. These guidelines recommend a communicative approach to the teaching and learning of te reo Māori. In this article, we discuss communicative approaches and provide examples of ways in which teachers can design communicative language lessons that are appropriate for very young learners, lessons that are not only fun but also effective in developing genuine communicative competence in te reo Māori.

text: Using the curriculum guidelines for the teaching and learning of te reo Māori in Years 1 – 13 of New Zealand schools to create lessons for young learners In 2009, The New Zealand Ministry of Education published curriculum guidelines for te reo Maori in Years 1 – 13 of English-medium New Zealand schools, that is, from age 5 upwards. These guidelines recommend a communicative approach to the teaching and learning of te reo Māori. In this article, we discuss communicative approaches and provide examples of ways in which teachers can design communicative language lessons that are appropriate for very young learners, lessons that are not only fun but also effective in developing genuine communicative competence in te reo Māori.

year: 2009-09