title: Satellite remote sensing for improvement of groundwater characterisation

authors: Westerhoff, Rogier Sebastiaan

subjects: satellite

abstract: Groundwater, the water stored in the subsurface, plays an essential role in water provision for domestic, industrial and agricultural use. Groundwater is also vital for ecology and environment, since it provides base flow to many streams, rivers and wetlands. Groundwater demand in New Zealand has grown strongly in recent years and assessment of groundwater volumes, fluxes and flows requires more advanced methods. Exploration of groundwater, the least-known water resource, often requires the combination of multiple research disciplines, such as well-drilling, geophysical techniques and groundwater models. These combined products often are uncertain in areas where ground-observed data are sparse. This uncertainty limits our future scientifc capability to better assess our complex groundwater resources.

Satellite geophysical data can help tackle the problem of data sparsity in groundwater research because they commonly cover several regions or a whole nation in one image. On a global scale, in recent years, use of satellite-derived data in hydrogeology has gained considerable attention. Although data access is relatively easy and data are mostly free, similar in-depth hydrogeological studies have not been performed for New Zealand. This is mainly because satellite data can contain much noise, as the signal has to travel far before it reaches the Earth, and because data are often too coarse for the New Zealand aquifer scale. Therefore, satellite data for hydrogeological research in New Zealand are not proven technology and they are generally not used by New Zealand scientists, consultancies or water managers. A break-through is needed.

This thesis researches the added value of satellite data to better estimate groundwater volumes and flows, including their uncertainties, in New Zealand. The thesis uses the concept of `efficient combination', where satellite data are combined with existing information from ground observations or models, so that they can fill in gaps and trends in data-sparse areas. The satellite data used are those on evapotranspiration, vegetation properties, and soil moisture (the amount of water stored in our top soils). These water budget components are important input for the estimation of rainfall recharge to groundwater: the amount of rainfall that percolates through the soil to eventually replenish the groundwater. Rainfall recharge to groundwater is an important component for groundwater flow models. This thesis shows that satellite data can be used as a tool with other data (e.g., with ground observations and models) to better spatially estimate evapotranspiration, soil moisture, rainfall recharge and groundwater table, including their uncertainty estimates. Satellite data thus help to better estimate groundwater volumes, fluxes, and flows, at both the regional and national scale. This thesis has resulted in the first New Zealand-wide gridded estimates of rainfall recharge and groundwater table. 

With my thesis, I hope to have paved the way for further use of satellite-derived data sources in groundwater research. I am confident that the results and recommendations of this thesis will lead to a further increase of New Zealand research and applications of satellite data for groundwater and freshwater studies.

text: Satellite remote sensing for improvement of groundwater characterisation Groundwater, the water stored in the subsurface, plays an essential role in water provision for domestic, industrial and agricultural use. Groundwater is also vital for ecology and environment, since it provides base flow to many streams, rivers and wetlands. Groundwater demand in New Zealand has grown strongly in recent years and assessment of groundwater volumes, fluxes and flows requires more advanced methods. Exploration of groundwater, the least-known water resource, often requires the combination of multiple research disciplines, such as well-drilling, geophysical techniques and groundwater models. These combined products often are uncertain in areas where ground-observed data are sparse. This uncertainty limits our future scientifc capability to better assess our complex groundwater resources.

Satellite geophysical data can help tackle the problem of data sparsity in groundwater research because they commonly cover several regions or a whole nation in one image. On a global scale, in recent years, use of satellite-derived data in hydrogeology has gained considerable attention. Although data access is relatively easy and data are mostly free, similar in-depth hydrogeological studies have not been performed for New Zealand. This is mainly because satellite data can contain much noise, as the signal has to travel far before it reaches the Earth, and because data are often too coarse for the New Zealand aquifer scale. Therefore, satellite data for hydrogeological research in New Zealand are not proven technology and they are generally not used by New Zealand scientists, consultancies or water managers. A break-through is needed.

This thesis researches the added value of satellite data to better estimate groundwater volumes and flows, including their uncertainties, in New Zealand. The thesis uses the concept of `efficient combination', where satellite data are combined with existing information from ground observations or models, so that they can fill in gaps and trends in data-sparse areas. The satellite data used are those on evapotranspiration, vegetation properties, and soil moisture (the amount of water stored in our top soils). These water budget components are important input for the estimation of rainfall recharge to groundwater: the amount of rainfall that percolates through the soil to eventually replenish the groundwater. Rainfall recharge to groundwater is an important component for groundwater flow models. This thesis shows that satellite data can be used as a tool with other data (e.g., with ground observations and models) to better spatially estimate evapotranspiration, soil moisture, rainfall recharge and groundwater table, including their uncertainty estimates. Satellite data thus help to better estimate groundwater volumes, fluxes, and flows, at both the regional and national scale. This thesis has resulted in the first New Zealand-wide gridded estimates of rainfall recharge and groundwater table. 

With my thesis, I hope to have paved the way for further use of satellite-derived data sources in groundwater research. I am confident that the results and recommendations of this thesis will lead to a further increase of New Zealand research and applications of satellite data for groundwater and freshwater studies.

year: 2017

title: Axial Variations and Entry Effects in a Pressure Screen

authors: Atkins, Martin John

subjects: Pressure Screening

abstract: Pressure screens are used for contaminant removal and fibre length fractionation in the production of pulp and paper products.  Axial variations and entry effects in the screen are known to occur and these variations have not been adequately quantified.  This thesis describes a fundamental study of the axial variations of several factors that occur within an industrial pressure screen; namely, pulp consistency, fibre length distribution, rotor pressure pulse, and feed annulus tangential velocity.

Axial variations of pulp consistency in the screen annulus and the accept chamber of the screen were studied using an internal radial sampling method.  Localised pulp samples were taken and evaluated and common measures of screen performance such as fibre passage ratio and fractionation efficiency were calculated along the screen.  Consistency generally increased along the length of the screen although under certain conditions the consistency toward the front of the screen was lower than the feed consistency.  A two passage ratio model that incorporated forward and reverse passage ratio was derived to elucidate the flow of both fibre and fluid through the screen and their effects on overall screen performance.  The passage of fibre through the screen decreased with screen length which generally had a positive effect on the fractionation efficiency toward the back of the screen.  The passage of individual fibre length fractions was also studied and it was found that long fibre had a much lower passage than short fibre which caused the average fibre length in the annulus to increase.  

Rotor induced pressure pulse variations along the screen length were also investigated.  The magnitude of the pressure pulse was significantly lower (up to 40 %) at the rear of the screen.  The variation in pressure caused by the rotor is due to a Venturi effect and the shape of the rotor.  The relative velocity of the fluid and the rotor, called the slip factor, also directly affects the size of the pressure pulse in the annulus.  The slip factor decreases along the length of the screen due to the increase in tangential velocity of the fluid.  Pressure pulse data was also used to estimate the instantaneous aperture velocity and back-flush ratio.  The instantaneous aperture velocity was calculated to vary considerably from the superficial aperture velocity by up to 5 m/s in the forward direction and 10 m/s in the reverse direction.   
Computational Fluid Dynamics (CFD) was used to model tangential velocity changes in simplified screen annuli with axial through flow.  For a smooth screen rotor the mean tangential velocity increased over the entire length of the annulus without reaching a maximum value.  A step and bump rotor were modelled and the shape of the pressure pulses showed good agreement with experimentally measured pulses.  The mean tangential velocity and the entrance length were found to be heavily dependant on the screen rotor used.

text: Axial Variations and Entry Effects in a Pressure Screen Pressure screens are used for contaminant removal and fibre length fractionation in the production of pulp and paper products.  Axial variations and entry effects in the screen are known to occur and these variations have not been adequately quantified.  This thesis describes a fundamental study of the axial variations of several factors that occur within an industrial pressure screen; namely, pulp consistency, fibre length distribution, rotor pressure pulse, and feed annulus tangential velocity.

Axial variations of pulp consistency in the screen annulus and the accept chamber of the screen were studied using an internal radial sampling method.  Localised pulp samples were taken and evaluated and common measures of screen performance such as fibre passage ratio and fractionation efficiency were calculated along the screen.  Consistency generally increased along the length of the screen although under certain conditions the consistency toward the front of the screen was lower than the feed consistency.  A two passage ratio model that incorporated forward and reverse passage ratio was derived to elucidate the flow of both fibre and fluid through the screen and their effects on overall screen performance.  The passage of fibre through the screen decreased with screen length which generally had a positive effect on the fractionation efficiency toward the back of the screen.  The passage of individual fibre length fractions was also studied and it was found that long fibre had a much lower passage than short fibre which caused the average fibre length in the annulus to increase.  

Rotor induced pressure pulse variations along the screen length were also investigated.  The magnitude of the pressure pulse was significantly lower (up to 40 %) at the rear of the screen.  The variation in pressure caused by the rotor is due to a Venturi effect and the shape of the rotor.  The relative velocity of the fluid and the rotor, called the slip factor, also directly affects the size of the pressure pulse in the annulus.  The slip factor decreases along the length of the screen due to the increase in tangential velocity of the fluid.  Pressure pulse data was also used to estimate the instantaneous aperture velocity and back-flush ratio.  The instantaneous aperture velocity was calculated to vary considerably from the superficial aperture velocity by up to 5 m/s in the forward direction and 10 m/s in the reverse direction.   
Computational Fluid Dynamics (CFD) was used to model tangential velocity changes in simplified screen annuli with axial through flow.  For a smooth screen rotor the mean tangential velocity increased over the entire length of the annulus without reaching a maximum value.  A step and bump rotor were modelled and the shape of the pressure pulses showed good agreement with experimentally measured pulses.  The mean tangential velocity and the entrance length were found to be heavily dependant on the screen rotor used.

year: 2007

title: The contribution of family literacy programmes to the wellbeing of individuals, families and communities

authors: Furness, Jane Amanda

subjects: Adult Literacy Strategy

abstract: Approaches to literacy education named as ‘family literacy programmes’ first emerged in Aotearoa New Zealand in the early 2000s amidst considerable enthusiasm. Such approaches involve adults, children, or both in literacy learning in the contexts of home and family life. They are part of a wider field, established internationally, of academic and practical endeavour encompassing studies of the literacy practices of family members, studies of parents’ support of children’s literacy development, and studies of programmes aimed at enhancing family members’ literacy abilities, and the evaluations of such programmes. It is a contentious field, with divergent views of what constitutes both literacy and family, leading to differing expectations of what programmes are for and what they might achieve. From a moral perspective, hopes for such approaches, which hold much intuitive and culturally-located appeal, must be set against the concerning disparities in wellbeing between different groups, evident and growing in New Zealand as elsewhere. 

The study set out to explore the effects of a range of family-focused approaches in New Zealand, and their characteristics that seemed important in achieving relevant and meaningful outcomes for participants and their families. An important aim of the study was to encourage the essential conversation concerning the ideological and research-informed basis on which policies and practices should be developed to best suit our contexts, and that have people’s overall wellbeing, as well as their literacy development, in mind. The study traced the experiences of nineteen mainly Māori, Pacific and Pākehā adult participants in four varying family-focused literacy programmes located in different kinds of communities, drawing on Kaupapa Māori methodologies in its approach. Conversational interviews with the adult participants, programme staff and others who knew the participants well, repeated over 18 months, as well as participant observations of programme sessions and programme documentation, formed an extensive data set for latent theoretical thematic analysis. I identified literacy and other changes in the participants’ lives; synergistic links between factors influencing the programme effects, ‘flow on’ of effects to wider aspects of the participants’ lives and to their families and communities, and links to the personal, relational and collective wellbeing of individuals, families and communities.

The findings demonstrate that there are complex influences on programmes such that effects are highly individualised, but that there is nevertheless a tangible, discernable process in play as people journey from participation to wellbeing, in which literacy enhancement, familiarity with new literacies, and new uses of literacies, are involved. The study suggests a disjuncture between current literacy education policy and the hopes, aspirations and real lives of many people for whom the programmes are intended and who wish to contribute to their families and communities despite their complex and often fraught lives. It also demonstrates that a deep level of care and holistic concern is possible in a programme which also achieves literacy skill development. Recognition of people’s whole selves including their problems and their existing abilities in programme content and approach demonstrated the ‘respectful relevance’ that appears crucial to the involvement and the positive (useful and meaningful) outcomes that were observed. It demonstrated that a broad and inclusive evaluative lens offers the best hope for full appreciation of the contribution of programmes such as these, when the overall wellbeing of families, communities and society as a whole is placed at the centre of literacy work. 

The study offers new and urgently-needed ecological systems-based models within a wellbeing orientation to family literacy theory. These have implications for the future development of programmes in Aotearoa New Zealand and provide frameworks against which programmes internationally may consider their work afresh. The study calls for greater community relevance in family literacy based on local values and aspirations.

text: The contribution of family literacy programmes to the wellbeing of individuals, families and communities Approaches to literacy education named as ‘family literacy programmes’ first emerged in Aotearoa New Zealand in the early 2000s amidst considerable enthusiasm. Such approaches involve adults, children, or both in literacy learning in the contexts of home and family life. They are part of a wider field, established internationally, of academic and practical endeavour encompassing studies of the literacy practices of family members, studies of parents’ support of children’s literacy development, and studies of programmes aimed at enhancing family members’ literacy abilities, and the evaluations of such programmes. It is a contentious field, with divergent views of what constitutes both literacy and family, leading to differing expectations of what programmes are for and what they might achieve. From a moral perspective, hopes for such approaches, which hold much intuitive and culturally-located appeal, must be set against the concerning disparities in wellbeing between different groups, evident and growing in New Zealand as elsewhere. 

The study set out to explore the effects of a range of family-focused approaches in New Zealand, and their characteristics that seemed important in achieving relevant and meaningful outcomes for participants and their families. An important aim of the study was to encourage the essential conversation concerning the ideological and research-informed basis on which policies and practices should be developed to best suit our contexts, and that have people’s overall wellbeing, as well as their literacy development, in mind. The study traced the experiences of nineteen mainly Māori, Pacific and Pākehā adult participants in four varying family-focused literacy programmes located in different kinds of communities, drawing on Kaupapa Māori methodologies in its approach. Conversational interviews with the adult participants, programme staff and others who knew the participants well, repeated over 18 months, as well as participant observations of programme sessions and programme documentation, formed an extensive data set for latent theoretical thematic analysis. I identified literacy and other changes in the participants’ lives; synergistic links between factors influencing the programme effects, ‘flow on’ of effects to wider aspects of the participants’ lives and to their families and communities, and links to the personal, relational and collective wellbeing of individuals, families and communities.

The findings demonstrate that there are complex influences on programmes such that effects are highly individualised, but that there is nevertheless a tangible, discernable process in play as people journey from participation to wellbeing, in which literacy enhancement, familiarity with new literacies, and new uses of literacies, are involved. The study suggests a disjuncture between current literacy education policy and the hopes, aspirations and real lives of many people for whom the programmes are intended and who wish to contribute to their families and communities despite their complex and often fraught lives. It also demonstrates that a deep level of care and holistic concern is possible in a programme which also achieves literacy skill development. Recognition of people’s whole selves including their problems and their existing abilities in programme content and approach demonstrated the ‘respectful relevance’ that appears crucial to the involvement and the positive (useful and meaningful) outcomes that were observed. It demonstrated that a broad and inclusive evaluative lens offers the best hope for full appreciation of the contribution of programmes such as these, when the overall wellbeing of families, communities and society as a whole is placed at the centre of literacy work. 

The study offers new and urgently-needed ecological systems-based models within a wellbeing orientation to family literacy theory. These have implications for the future development of programmes in Aotearoa New Zealand and provide frameworks against which programmes internationally may consider their work afresh. The study calls for greater community relevance in family literacy based on local values and aspirations.

year: 2012