title: Measurements and modelling of the tidal salt intrusion along the Waihou River

authors: James, Brooke

subjects: salt intrusion

abstract: Salt intrusions can exist within rivers and are influenced by shape of an estuary and tidal and river flows. Incoming tidal water moves into a region of freshwater influence which can have a strong influence on biological and geochemical properties in the water column. These features constitute a transition zone with spatially and temporally varying dynamics. As such, it is challenging to correctly represent these features in numerical hydrodynamic and sediment transport models. We report field observations of the salt intrusion processes in the Waihou River estuary in New Zealand. Most of the research that has been conducted thus far on the Waihou River has centred around sediment transport, gold mining impacts, water quality and fish populations and there is a lack of systematic collection of vertical water property data. Measurements of water column properties (salinity, temperature and turbidity) were taken at different tidal stages and river flows and used to track the movement and characteristics of the salt intrusion. In-situ water samples were collected and used to form a calibration for suspended sediment concentrations. The salinity intrusion was observed to intrude to 7.2-11.8 km (at 1 PSU) upstream from the mouth of the river. The estuary exhibited both mixed and stratified conditions, with a clear salt wedge shape observed for only one out of five surveys. The salinity intrusion length appeared to be primarily controlled by the by river flow, with a shorter intrusion length and stronger stratification occurring for higher river flows. Greater turbidity was observed within the marine water compared to fluvial waters, and turbidity was greater near the bed implying that the primary delivery mechanism of sediment to the lower reaches of the river is import from the offshore or intertidal marine regions. Numerical hydrodynamic modelling using Delft 3D was undertaken and was compared to the field data. While the model had previously been calibrated for water levels and velocity in two-dimensions, the adapted 3D version of the model did not accurately predict the structure or extent of the salinity intrusion. Model results under-estimated the salinity intrusion, which was attributed to over-mixing of the water column, however, the performance improved when a lower value for horizontal eddy diffusivity was used. This work emphasises the need to obtain vertically resolved data sets to allow for robust calibration of numerical models, which are commonly used in environmental management decisions.

text: Measurements and modelling of the tidal salt intrusion along the Waihou River Salt intrusions can exist within rivers and are influenced by shape of an estuary and tidal and river flows. Incoming tidal water moves into a region of freshwater influence which can have a strong influence on biological and geochemical properties in the water column. These features constitute a transition zone with spatially and temporally varying dynamics. As such, it is challenging to correctly represent these features in numerical hydrodynamic and sediment transport models. We report field observations of the salt intrusion processes in the Waihou River estuary in New Zealand. Most of the research that has been conducted thus far on the Waihou River has centred around sediment transport, gold mining impacts, water quality and fish populations and there is a lack of systematic collection of vertical water property data. Measurements of water column properties (salinity, temperature and turbidity) were taken at different tidal stages and river flows and used to track the movement and characteristics of the salt intrusion. In-situ water samples were collected and used to form a calibration for suspended sediment concentrations. The salinity intrusion was observed to intrude to 7.2-11.8 km (at 1 PSU) upstream from the mouth of the river. The estuary exhibited both mixed and stratified conditions, with a clear salt wedge shape observed for only one out of five surveys. The salinity intrusion length appeared to be primarily controlled by the by river flow, with a shorter intrusion length and stronger stratification occurring for higher river flows. Greater turbidity was observed within the marine water compared to fluvial waters, and turbidity was greater near the bed implying that the primary delivery mechanism of sediment to the lower reaches of the river is import from the offshore or intertidal marine regions. Numerical hydrodynamic modelling using Delft 3D was undertaken and was compared to the field data. While the model had previously been calibrated for water levels and velocity in two-dimensions, the adapted 3D version of the model did not accurately predict the structure or extent of the salinity intrusion. Model results under-estimated the salinity intrusion, which was attributed to over-mixing of the water column, however, the performance improved when a lower value for horizontal eddy diffusivity was used. This work emphasises the need to obtain vertically resolved data sets to allow for robust calibration of numerical models, which are commonly used in environmental management decisions.

year: 2024

title: Puer tea: Ancient caravans and urban chic [Book Review]

authors: Galikowski, Maria

abstract: This article reviews the book “ Puer Tea: Ancient Caravans and Urban Chic" by Jinghong Zhang.

text: Puer tea: Ancient caravans and urban chic [Book Review] This article reviews the book “ Puer Tea: Ancient Caravans and Urban Chic" by Jinghong Zhang.

year: 2015

title: Kei hea te tangi a te Tūī? An exploration of Kaitiakitanga in urban spaces

authors: Walker, Erana

subjects: Kaitiakitanga

abstract: Indigenous people’s connection to the natural world differs from place to place. In Aotearoa, New Zealand, Māori connection to nature is often articulated through the concept of kaitiakitanga whilst intertwining concepts of whakapapa, wairua, mana, mauri and place. Kaitiakitanga captures the relationships, narratives and practices that Māori utilise to protect kin of the natural environment as well as Māori communities in general. Over recent decades increase use of kaitiakitanga with respect to resource management has been linked to ideas of guardianship and stewardship, departing from important aspects such as place, whakapapa, intergenerational knowledge, spirituality and resource use. Calls to recognise the diverse ways kaitiakitanga has and can be expressed by Māori have echoed through academic literature, encouraging wider perspectives and application of the concept to develop. This has reinvigorated not only the need for natures protection but also the recognition of cultural knowledges and concepts in practicing kaitiakitanga. 
 
As with most indigenous people, Māori have experienced urbanisation that has spanned across generations of whānau and hapū. Urbanisation has the ability to challenge health outcomes, cultural practices and cultural knowledge, and more importantly, relationships to nature. Growing urbanisation and environmental degradation continue to challenge people and our relationships to nature. There is now a need to understand how urban spaces may also challenge the concepts that encourage connections to nature like kaitiakitanga. Moreover, there is a need to understand if such cultural concepts can become challenged when transient Māori reside in another tribal group’s boundaries. This research provides a deeper analysis of kaitiakitanga by understanding its application within the urban space of Kirikiriroa/Hamilton. From data gathered through a survey, focus groups and interviews, this research project illustrates the experiences of Māori in the urban space who know and practice kaitiakitanga in Kirikiriroa/Hamilton. More importantly, this study posits the integral role of place connection and mana in supporting and shaping kaitiakitanga practices in urban spaces.

The data from participants shows a clear narrative of kaitiakitanga from both local and transient Māori exist and indicates that kaitiakitanga is practiced in accordance with their location and whakapapa to their area of residence. The study has found that kaitiakitanga practices have adapted to suit urban spaces allowing for both transient and local knowledges to exist within the urban space. The key findings of this research show many influences that impact kaitiakitanga practices like the recognition of childhood spaces and experiences, ideas of kinship, cultural knowledges, spirituality, mobility, nature as well as modernisation. Through exploring participants use and knowledge of kaitiakitanga, this research provides a new lens in which to view this concept and bring to the fore, the various experiences and ways that participants connect to place, people, culture and most importantly, nature.

text: Kei hea te tangi a te Tūī? An exploration of Kaitiakitanga in urban spaces Indigenous people’s connection to the natural world differs from place to place. In Aotearoa, New Zealand, Māori connection to nature is often articulated through the concept of kaitiakitanga whilst intertwining concepts of whakapapa, wairua, mana, mauri and place. Kaitiakitanga captures the relationships, narratives and practices that Māori utilise to protect kin of the natural environment as well as Māori communities in general. Over recent decades increase use of kaitiakitanga with respect to resource management has been linked to ideas of guardianship and stewardship, departing from important aspects such as place, whakapapa, intergenerational knowledge, spirituality and resource use. Calls to recognise the diverse ways kaitiakitanga has and can be expressed by Māori have echoed through academic literature, encouraging wider perspectives and application of the concept to develop. This has reinvigorated not only the need for natures protection but also the recognition of cultural knowledges and concepts in practicing kaitiakitanga. 
 
As with most indigenous people, Māori have experienced urbanisation that has spanned across generations of whānau and hapū. Urbanisation has the ability to challenge health outcomes, cultural practices and cultural knowledge, and more importantly, relationships to nature. Growing urbanisation and environmental degradation continue to challenge people and our relationships to nature. There is now a need to understand how urban spaces may also challenge the concepts that encourage connections to nature like kaitiakitanga. Moreover, there is a need to understand if such cultural concepts can become challenged when transient Māori reside in another tribal group’s boundaries. This research provides a deeper analysis of kaitiakitanga by understanding its application within the urban space of Kirikiriroa/Hamilton. From data gathered through a survey, focus groups and interviews, this research project illustrates the experiences of Māori in the urban space who know and practice kaitiakitanga in Kirikiriroa/Hamilton. More importantly, this study posits the integral role of place connection and mana in supporting and shaping kaitiakitanga practices in urban spaces.

The data from participants shows a clear narrative of kaitiakitanga from both local and transient Māori exist and indicates that kaitiakitanga is practiced in accordance with their location and whakapapa to their area of residence. The study has found that kaitiakitanga practices have adapted to suit urban spaces allowing for both transient and local knowledges to exist within the urban space. The key findings of this research show many influences that impact kaitiakitanga practices like the recognition of childhood spaces and experiences, ideas of kinship, cultural knowledges, spirituality, mobility, nature as well as modernisation. Through exploring participants use and knowledge of kaitiakitanga, this research provides a new lens in which to view this concept and bring to the fore, the various experiences and ways that participants connect to place, people, culture and most importantly, nature.

year: 2021