title: Nearshore sediment dynamics in a mixed sand/mud environment

authors: Beamsley, Brett James

abstract: Poverty Bay, on the New Zealand's northeast coastline, is a high-energy coastal embayment that receives significant quantities of fine, fluvial sediment from two river systems. Examining seabed geomechanical characteristics, sediment fluxes and morphological features in northern Poverty Bay provided the opportunity to study interactive processes, including sediment entrainment rates over the cohesively bound mixed sand/mud seabeds, and the dispersion of a turbid river plume. Three field experiments and an extensive seabed-sampling programme were undertaken, and a 2-cell numerical model was developed and validated against infilling rates of the port of Gisborne navigation channel. The implications for existing and future operations at the port of Gisborne, including the suitability of capital and maintenance dredged material for use in reclamation, have been evaluated. 

Within the study site, near-bed wave orbital velocities and fluvial inputs control the spatial variability in the seabed sediment textural characteristics, with the seabed grain size decreasing with depth and distance from the mouth of the Turanganui River. A hand-held shear vane was used to quantify the in-situ shear strength of the cohesively bonded mud/sand surficial sediment, and the in-situ shear strength has been correlated (R² = 0.83) with the cumulative effect of several of the sediment textural and environmental parameters. 

Near-bed sediment diffusion and entrainment was examined using an array of micro-scale inline pumps. The effect that cohesive bonding of the mixed sand/mud seabed has on retarding the entrainment rate was examined by considering both the textural and geomechanical characteristics of the seabed. No correlation was found between the ratios of estimated to predicted near bed reference concentration (ζ) and either the median grain size (d₅₀) or the ratio of percent sand to mud of the seabed. However, a good correlation was found between ζ and the normalised in-situ shear strength (𝑥) of the seabed (adjusted R² = 0.99), with the relationship of the form, 

𝑙n(ζ) = -0.51-1.30 𝑥³ 

The conversion of the downward flux from sediment traps to a time-averaged suspended sediment concentration (SSC), and near bed reference concentration (C₀) was found to be critically dependant on the fall velocity statistic (w∫) of the grain size distribution. Due to flocculation of the near-bed suspended sediment, the dispersed equivalent w∫ distribution and median w∫ of the distribution resulted in poor predictions of C₀. Instead, an in-situ ‘effective’ w∫ distribution of the suspended sediment was developed using the measured 𝑙ₛ from individual dispersed grain size bins within the SSC profile and the predicted sediment diffusivity (εₛ). C₀ predicted using the effective w∫ distribution agreed with pumped samples and theory predicted C₀, and provided a robust method of determining the time-averaged SSC of mixed sand/mud sediment using sediment traps. 

The diffusion of sediment within the near-bed SSC profile varied as a function of w∫, with relatively finer sediment exhibiting less diffusion. The mixing length (𝑙ₛ) profile was well approximated by a linear profile, with 𝑙ₛ varying as a function of elevation (z) and the von Karman constant (κ), i.e. 𝑙ₛ = κ𝚣. Within 4-8 cm of the bed 𝑙ₛ is constant and equal to 0.06 m.

β is defined as the ratio of sediment diffusivity (εₛ) to eddy viscosity (ε∫), and is commonly used as a correction factor for predictive SSC profile equations. By examining the diffusion of sediment within the near-bed SSC profile a new equation for β was obtained,

 	𝑙n( β ) = -0. 95 - 0.4ψ / 𝑙n(ψ) 

The horizontal diffusion of sediment within the Turanganui River plume was found to be a function of the distance (x) from the mouth of the Turanganui River and a decay rate factor (Dₓ), where

 	Cₓ = Cₒbe ⁽⁻ ͯ/ᴰͯ ⁾

The form of the equation is similar to the Nielsen time-averaged gradient diffusion equation. Dₓ was correlated (R² = 0.92) with river discharge (φᵣᵢᵥₑᵣ), and found to exponentially decrease with increasing φᵣᵢᵥₑᵣ, where 

	Dₓ = 591+2850 exp(⁻ᵠʳⁱᵛᵉʳ/2.1)

The relationship suggests that the effective w∫ of the suspended sediment within the plume increases with increasing SSC, presumably due to increased flocculated particle size. Based on the developed empirical formulae the Turanganui River is predicted to discharge 7.6x10⁷ kg of fluvial derived sediment into Poverty Bay on an annual basis. 

The developed relationships and formulae that describe the hydrodynamical processes within northern Poverty Bay have been implemented in a 2-cell numerical model that considers both downward and horizontal sediment fluxes. The port of Gisborne shipping channel infilling rate, as determined from hydrographic surveys and dredging records, was used to validate the model. The 2-cell numerical model accurately predicts channel infilling rates, and provides an insight into the governing hydrodynamical processes in northern Poverty Bay. The developed model represents an alternative to the implementation of a full 3-dimensional hydrodynamic model. 

Hydrographic surveys and dredging records show the channel area passes through the beach nearshore zone, and during the monitoring period maintenance dredging only maintained the channel design depth along the channel leads, while significant infilling occurred near the channel edges (Δh = -1 m). Extrapolation of the results suggests an annual channel infilling rate of 171,400 m³ per year, corresponding to a maintenance dredging cost of approximately $857,000 to $1,200,000 per annum. Wave and river discharge conditions during the monitoring period were smaller than average, and more infilling is expected during stormy years. 

Relocating the channel and port entrance to a site in deeper water, further from the mouth of the Turanganui River, with relatively strong seabed in-situ shear strength is identified as a means of reducing dredging costs. The material dredged from the shipping channel is suitable for use in land-based reclamation, particularly if the soil structure is improved by addition of a coarser material such as of the underlying mudstone unit. The bearing capacity of the reclamation can be improved by mixing the mud/sand with concrete to create mudcrete.

text: Nearshore sediment dynamics in a mixed sand/mud environment Poverty Bay, on the New Zealand's northeast coastline, is a high-energy coastal embayment that receives significant quantities of fine, fluvial sediment from two river systems. Examining seabed geomechanical characteristics, sediment fluxes and morphological features in northern Poverty Bay provided the opportunity to study interactive processes, including sediment entrainment rates over the cohesively bound mixed sand/mud seabeds, and the dispersion of a turbid river plume. Three field experiments and an extensive seabed-sampling programme were undertaken, and a 2-cell numerical model was developed and validated against infilling rates of the port of Gisborne navigation channel. The implications for existing and future operations at the port of Gisborne, including the suitability of capital and maintenance dredged material for use in reclamation, have been evaluated. 

Within the study site, near-bed wave orbital velocities and fluvial inputs control the spatial variability in the seabed sediment textural characteristics, with the seabed grain size decreasing with depth and distance from the mouth of the Turanganui River. A hand-held shear vane was used to quantify the in-situ shear strength of the cohesively bonded mud/sand surficial sediment, and the in-situ shear strength has been correlated (R² = 0.83) with the cumulative effect of several of the sediment textural and environmental parameters. 

Near-bed sediment diffusion and entrainment was examined using an array of micro-scale inline pumps. The effect that cohesive bonding of the mixed sand/mud seabed has on retarding the entrainment rate was examined by considering both the textural and geomechanical characteristics of the seabed. No correlation was found between the ratios of estimated to predicted near bed reference concentration (ζ) and either the median grain size (d₅₀) or the ratio of percent sand to mud of the seabed. However, a good correlation was found between ζ and the normalised in-situ shear strength (𝑥) of the seabed (adjusted R² = 0.99), with the relationship of the form, 

𝑙n(ζ) = -0.51-1.30 𝑥³ 

The conversion of the downward flux from sediment traps to a time-averaged suspended sediment concentration (SSC), and near bed reference concentration (C₀) was found to be critically dependant on the fall velocity statistic (w∫) of the grain size distribution. Due to flocculation of the near-bed suspended sediment, the dispersed equivalent w∫ distribution and median w∫ of the distribution resulted in poor predictions of C₀. Instead, an in-situ ‘effective’ w∫ distribution of the suspended sediment was developed using the measured 𝑙ₛ from individual dispersed grain size bins within the SSC profile and the predicted sediment diffusivity (εₛ). C₀ predicted using the effective w∫ distribution agreed with pumped samples and theory predicted C₀, and provided a robust method of determining the time-averaged SSC of mixed sand/mud sediment using sediment traps. 

The diffusion of sediment within the near-bed SSC profile varied as a function of w∫, with relatively finer sediment exhibiting less diffusion. The mixing length (𝑙ₛ) profile was well approximated by a linear profile, with 𝑙ₛ varying as a function of elevation (z) and the von Karman constant (κ), i.e. 𝑙ₛ = κ𝚣. Within 4-8 cm of the bed 𝑙ₛ is constant and equal to 0.06 m.

β is defined as the ratio of sediment diffusivity (εₛ) to eddy viscosity (ε∫), and is commonly used as a correction factor for predictive SSC profile equations. By examining the diffusion of sediment within the near-bed SSC profile a new equation for β was obtained,

 	𝑙n( β ) = -0. 95 - 0.4ψ / 𝑙n(ψ) 

The horizontal diffusion of sediment within the Turanganui River plume was found to be a function of the distance (x) from the mouth of the Turanganui River and a decay rate factor (Dₓ), where

 	Cₓ = Cₒbe ⁽⁻ ͯ/ᴰͯ ⁾

The form of the equation is similar to the Nielsen time-averaged gradient diffusion equation. Dₓ was correlated (R² = 0.92) with river discharge (φᵣᵢᵥₑᵣ), and found to exponentially decrease with increasing φᵣᵢᵥₑᵣ, where 

	Dₓ = 591+2850 exp(⁻ᵠʳⁱᵛᵉʳ/2.1)

The relationship suggests that the effective w∫ of the suspended sediment within the plume increases with increasing SSC, presumably due to increased flocculated particle size. Based on the developed empirical formulae the Turanganui River is predicted to discharge 7.6x10⁷ kg of fluvial derived sediment into Poverty Bay on an annual basis. 

The developed relationships and formulae that describe the hydrodynamical processes within northern Poverty Bay have been implemented in a 2-cell numerical model that considers both downward and horizontal sediment fluxes. The port of Gisborne shipping channel infilling rate, as determined from hydrographic surveys and dredging records, was used to validate the model. The 2-cell numerical model accurately predicts channel infilling rates, and provides an insight into the governing hydrodynamical processes in northern Poverty Bay. The developed model represents an alternative to the implementation of a full 3-dimensional hydrodynamic model. 

Hydrographic surveys and dredging records show the channel area passes through the beach nearshore zone, and during the monitoring period maintenance dredging only maintained the channel design depth along the channel leads, while significant infilling occurred near the channel edges (Δh = -1 m). Extrapolation of the results suggests an annual channel infilling rate of 171,400 m³ per year, corresponding to a maintenance dredging cost of approximately $857,000 to $1,200,000 per annum. Wave and river discharge conditions during the monitoring period were smaller than average, and more infilling is expected during stormy years. 

Relocating the channel and port entrance to a site in deeper water, further from the mouth of the Turanganui River, with relatively strong seabed in-situ shear strength is identified as a means of reducing dredging costs. The material dredged from the shipping channel is suitable for use in land-based reclamation, particularly if the soil structure is improved by addition of a coarser material such as of the underlying mudstone unit. The bearing capacity of the reclamation can be improved by mixing the mud/sand with concrete to create mudcrete.

year: 2003

title: The business of the other: representing the non-west in management and media

authors: Munshi, Debashish

abstract: This thesis explores current facets of the business of the other in western management and business media discourses. It identifies the shaping of these facets through continuities between imperial colonisation and contemporary neocolonialism in ways that mainstream management discourses marginalise or ignore. In establishing marginalisation and neglect, and opening up some of the consequences, the thesis draws on conceptual frameworks from indigenous, feminist, postcolonial, and subaltern studies. In addition, it argues that this ongoing incorporation of colonial concepts and practices into contemporary neocolonialism not only needs to be acknowledged but needs to be challenged by the reconceptualisation of current approaches to the other across a number of business fields.

After analysing the process of othering in the mainstream media through a study of the New Zealand press, the thesis focuses its four main lines of inquiry on the fields of business journalism, public relations, diversity management, and intercultural communication. In particular, it looks at aspects of western control involved in the ‘globalisation’ campaigns of the western media; the theoretical formulation of ‘requisite variety’ in public relations; the rhetoric of ‘managing diversity’ in organisations; and the formulation of ‘intercultural communication’ in education.

For the first line of inquiry, the thesis analyses how western business journalism texts exercise control over the other by updating Orientalist or Eurocentric ideologies as a discursive underpinning of, and accompaniment to, neocolonial economic expansion. Its second inquiry leads to a critique of the outwardly egalitarian concept of requisite variety in public relations literature. The thesis finds that, although this concept has allowed public relations to take note of the cultural other, it has, in a largely ethnocentric field, done little to shift the balance of power away from dominant western elites. Instead, it shows how the field operates to support those who already hold privileged positions and keep those on the margin marginalised.

In the third and fourth lines of inquiry, into discourses of diversity management and intercultural communication, similar consolidations of western neocolonial power are evident. While acknowledging attempts by these fields to incorporate the other into the larger organisational frame, the thesis tracks a systematic tendency to avoid or sideline issues of socio-political power in representations of diversity. It further contends that these benign-looking discourses of diversity align with the neocolonial west’s strategies to retain power in a world where major demographic shifts are reducing western populations to a numerical minority. 

The thesis also attempts, by introducing my lived experience as an other, to synthesise subjective observations with academic analysis. This integration of lived experience with the legitimacy of theory has been crucial to the project of the thesis as a whole. That project aims to resist sites of control entrenched in western worldviews and, in the face of persistent denials that they exist, to acknowledge racism and other potent discursive and material traces of imperialism.

text: The business of the other: representing the non-west in management and media This thesis explores current facets of the business of the other in western management and business media discourses. It identifies the shaping of these facets through continuities between imperial colonisation and contemporary neocolonialism in ways that mainstream management discourses marginalise or ignore. In establishing marginalisation and neglect, and opening up some of the consequences, the thesis draws on conceptual frameworks from indigenous, feminist, postcolonial, and subaltern studies. In addition, it argues that this ongoing incorporation of colonial concepts and practices into contemporary neocolonialism not only needs to be acknowledged but needs to be challenged by the reconceptualisation of current approaches to the other across a number of business fields.

After analysing the process of othering in the mainstream media through a study of the New Zealand press, the thesis focuses its four main lines of inquiry on the fields of business journalism, public relations, diversity management, and intercultural communication. In particular, it looks at aspects of western control involved in the ‘globalisation’ campaigns of the western media; the theoretical formulation of ‘requisite variety’ in public relations; the rhetoric of ‘managing diversity’ in organisations; and the formulation of ‘intercultural communication’ in education.

For the first line of inquiry, the thesis analyses how western business journalism texts exercise control over the other by updating Orientalist or Eurocentric ideologies as a discursive underpinning of, and accompaniment to, neocolonial economic expansion. Its second inquiry leads to a critique of the outwardly egalitarian concept of requisite variety in public relations literature. The thesis finds that, although this concept has allowed public relations to take note of the cultural other, it has, in a largely ethnocentric field, done little to shift the balance of power away from dominant western elites. Instead, it shows how the field operates to support those who already hold privileged positions and keep those on the margin marginalised.

In the third and fourth lines of inquiry, into discourses of diversity management and intercultural communication, similar consolidations of western neocolonial power are evident. While acknowledging attempts by these fields to incorporate the other into the larger organisational frame, the thesis tracks a systematic tendency to avoid or sideline issues of socio-political power in representations of diversity. It further contends that these benign-looking discourses of diversity align with the neocolonial west’s strategies to retain power in a world where major demographic shifts are reducing western populations to a numerical minority. 

The thesis also attempts, by introducing my lived experience as an other, to synthesise subjective observations with academic analysis. This integration of lived experience with the legitimacy of theory has been crucial to the project of the thesis as a whole. That project aims to resist sites of control entrenched in western worldviews and, in the face of persistent denials that they exist, to acknowledge racism and other potent discursive and material traces of imperialism.

year: 1999

title: Keynote Address: Barriers and incentives to Māori participation in the profession of psychology

authors: Levy, Michelle Patricia

subjects: Maori

abstract: It is well known that Māori are overrepresented
within the client group of
psychologists. Despite ongoing attempts to
recruit and retain more Māori within the
discipline of psychology, the numbers of
Māori psychologists continues to remain
low, raising serious concerns about the
ability of the profession to effectively meet
the needs of its clientele. The objectives of this study were to
identify the, barriers to, and incentives for improving the recruitment and retention
of Māori in the profession of
psychology and Māori to gain and maintain registration
as psychologists. This paper is
based on the full report provided to the
New Zealand Psychologists’ Board. The findings in this study
clearly demonstrate that in order to attract
Māori to participate in psychology, the
majority of environments need to change
substantially. It is simply not enough for
organisations, whether they are educational, professional, or service delivery agencies,
to identify the need for more Māori
psychologists, yet still fail to commit to,
and actively engage in, altering long
identified environmental factors that are
barriers to Māori participation.

text: Keynote Address: Barriers and incentives to Māori participation in the profession of psychology It is well known that Māori are overrepresented
within the client group of
psychologists. Despite ongoing attempts to
recruit and retain more Māori within the
discipline of psychology, the numbers of
Māori psychologists continues to remain
low, raising serious concerns about the
ability of the profession to effectively meet
the needs of its clientele. The objectives of this study were to
identify the, barriers to, and incentives for improving the recruitment and retention
of Māori in the profession of
psychology and Māori to gain and maintain registration
as psychologists. This paper is
based on the full report provided to the
New Zealand Psychologists’ Board. The findings in this study
clearly demonstrate that in order to attract
Māori to participate in psychology, the
majority of environments need to change
substantially. It is simply not enough for
organisations, whether they are educational, professional, or service delivery agencies,
to identify the need for more Māori
psychologists, yet still fail to commit to,
and actively engage in, altering long
identified environmental factors that are
barriers to Māori participation.

year: 2003