title: The role of intratidal oscillations in sediment resuspension in a diurnal, partially mixed estuary

authors: O’Callaghan, J.M.

subjects: diurnal tides

abstract: Using detailed observations of the mean and turbulent properties of flow, salinity and turbidity that spanned 2001/02, we examined the physical mechanisms underpinning sediment resuspension in the low-energy Swan River estuary, Western Australia. In this diurnal tidally-dominated estuary, the presence of intratidal oscillations, a tidal inequality lasting 2 to 3 hours on the flood tide, generated by interactions of the four main diurnal and semidiurnal astronomical constituents, K₁, O₁, M₂, and S₂, played a major role in modifying vertical stratification and mixing. These intratidal oscillations are controlled by phase differences between the tropic and synodic months rather than being temporally-fixed by bed friction, as occurs in semidiurnal estuaries. Intratidal oscillations are largest, at around 0.1 m, near to the Austral solstice when the lunar and solar declination are in-phase. Despite the seemingly small change in water level, shear-induced interfacial mixing caused destratification of the water column with the top-to-bottom salinity (ΔS) difference of 3.5 present early in the flood tide eroded to less than 0.3 by the end of the intratidal oscillation. High turbidity peaks, of 250 nephelometric turbidity units, coincided with these intratidal oscillations and could not be explained by bed friction since shear stress from mean flow did not exceed threshold criteria. High Reynolds stresses of ∼1 Nm⁻² did, however, exceed τcr and together with negative Reynolds fluxes indicate a net downward transport of material. Destratification of the water column induced by shear instabilities resulted in large overturns capable of moving in situ material towards the bed during intratidal oscillations and these turbidities were ∼10 times greater than those from bed-generated resuspension observed later during the flood tide.

text: The role of intratidal oscillations in sediment resuspension in a diurnal, partially mixed estuary Using detailed observations of the mean and turbulent properties of flow, salinity and turbidity that spanned 2001/02, we examined the physical mechanisms underpinning sediment resuspension in the low-energy Swan River estuary, Western Australia. In this diurnal tidally-dominated estuary, the presence of intratidal oscillations, a tidal inequality lasting 2 to 3 hours on the flood tide, generated by interactions of the four main diurnal and semidiurnal astronomical constituents, K₁, O₁, M₂, and S₂, played a major role in modifying vertical stratification and mixing. These intratidal oscillations are controlled by phase differences between the tropic and synodic months rather than being temporally-fixed by bed friction, as occurs in semidiurnal estuaries. Intratidal oscillations are largest, at around 0.1 m, near to the Austral solstice when the lunar and solar declination are in-phase. Despite the seemingly small change in water level, shear-induced interfacial mixing caused destratification of the water column with the top-to-bottom salinity (ΔS) difference of 3.5 present early in the flood tide eroded to less than 0.3 by the end of the intratidal oscillation. High turbidity peaks, of 250 nephelometric turbidity units, coincided with these intratidal oscillations and could not be explained by bed friction since shear stress from mean flow did not exceed threshold criteria. High Reynolds stresses of ∼1 Nm⁻² did, however, exceed τcr and together with negative Reynolds fluxes indicate a net downward transport of material. Destratification of the water column induced by shear instabilities resulted in large overturns capable of moving in situ material towards the bed during intratidal oscillations and these turbidities were ∼10 times greater than those from bed-generated resuspension observed later during the flood tide.

year: 2010

title: Review: Never a Dull Moment! Hamilton Stories

authors: Gush, Nadia

subjects: New Zealand

abstract: This article reviews the “Never a Dull Moment! Hamilton Stories”, Waikato Museum Te Whare Taonga o Waikato, 1 Grantham St, Hamilton

text: Review: Never a Dull Moment! Hamilton Stories This article reviews the “Never a Dull Moment! Hamilton Stories”, Waikato Museum Te Whare Taonga o Waikato, 1 Grantham St, Hamilton

year: 2010

title: Cultural knowledge and identity for wellbeing and success: Trying to make the connections in the north of New Zealand.

authors: Hohepa, Margie Kahukura

subjects: New Zealand

abstract: This paper argues that secure cultural identity is essential to wellbeing and cultural identity is important to Māori youth participation and success. The roles of community and schools in developing secure cultural identity are increasingly complex, as both become increasingly more culturally and ethnically diverse in many parts of the world.
The paper discusses findings from student survey data from a 2 year project ‘Te Wehi Nui a Mamao: Maximising the potential of tribal marae and regional language among youth', which began in July 2008, supported by funding from New Zealand's Foundation of Research, Science and Technology. This project aims to strengthen the relevance of tribal marae and regional Maori language among Maori youth, which are identified as important to Māori cultural identity.
Inter-generational transfer of tribal marae knowledge and language is becoming more compromised. Many cultural values are defined on marae. Tribal leaders have long been concerned about disconnections between Māori youth and tribal marae, poor knowledge of regional dialect and the potential negative consequences for full participation in society. .It appears that Māori youth are disconnected from regional language dialects and marae knowledge now more than ever. Reconnecting Māori youth with these two sources of tribal identity is the key to the purpose of this project.

text: Cultural knowledge and identity for wellbeing and success: Trying to make the connections in the north of New Zealand. This paper argues that secure cultural identity is essential to wellbeing and cultural identity is important to Māori youth participation and success. The roles of community and schools in developing secure cultural identity are increasingly complex, as both become increasingly more culturally and ethnically diverse in many parts of the world.
The paper discusses findings from student survey data from a 2 year project ‘Te Wehi Nui a Mamao: Maximising the potential of tribal marae and regional language among youth', which began in July 2008, supported by funding from New Zealand's Foundation of Research, Science and Technology. This project aims to strengthen the relevance of tribal marae and regional Maori language among Maori youth, which are identified as important to Māori cultural identity.
Inter-generational transfer of tribal marae knowledge and language is becoming more compromised. Many cultural values are defined on marae. Tribal leaders have long been concerned about disconnections between Māori youth and tribal marae, poor knowledge of regional dialect and the potential negative consequences for full participation in society. .It appears that Māori youth are disconnected from regional language dialects and marae knowledge now more than ever. Reconnecting Māori youth with these two sources of tribal identity is the key to the purpose of this project.

year: 2010