title: Nuclear power and the greenhouse effect

authors: Smith, Ron C.

subjects: nuclear power

abstract: When the inter-governmental Panel on climate Change (IPCC) met in Auckland in early February this year, this group was widely reported as being ‘increasingly certain’ that the atmosphere was warming and that is was due  to the burning of fossil fuels. Individuals at the meeting talked of dramatic changes in climate around the globe, of ice-caps melting, of large-scale inundation of low-lying land and of catastrophic consequences for human populations. Recent official publications in New Zealand have confirmed these judgements, speaking of global temperature rises of between 1 and 3.5 percent and sea level rises of half a metre over the next century.

text: Nuclear power and the greenhouse effect When the inter-governmental Panel on climate Change (IPCC) met in Auckland in early February this year, this group was widely reported as being ‘increasingly certain’ that the atmosphere was warming and that is was due  to the burning of fossil fuels. Individuals at the meeting talked of dramatic changes in climate around the globe, of ice-caps melting, of large-scale inundation of low-lying land and of catastrophic consequences for human populations. Recent official publications in New Zealand have confirmed these judgements, speaking of global temperature rises of between 1 and 3.5 percent and sea level rises of half a metre over the next century.

year: 2000

title: Temporal moments of a tracer pulse in a perfectly parallel flow system

authors: Bardsley, W. Earl

subjects: stratified aquifier

abstract: Perfectly parallel groundwater transport models partition water flow into isolated one-dimensional stream tubes which maintain total spatial correlation of all properties in the direction of flow. The case is considered of the temporal moments of a conservative tracer pulse released simultaneously into N stream tubes with arbitrarily different advective–dispersive transport and steady flow speeds in each of the stream tubes. No assumptions are made about the form of the individual stream tube arrival-time distributions or about the nature of the between-stream tube variation of hydraulic conductivity and flow speeds. The tracer arrival-time distribution g(t,x) is an N-component finite-mixture distribution, with the mean and variance of each component distribution increasing in proportion to tracer travel distance x. By utilising moment relations of finite mixture distributions, it is shown (to r=4) that the rth central moment of g(t,x) is an rth order polynomial function of x or φ, where φ is mean arrival time. In particular, the variance of g(t,x) is a positive quadratic function of x or φ. This generalises the well-known quadratic variance increase for purely advective flow in parallel flow systems and allows a simple means of regression estimation of the large-distance coefficient of variation of g(t,x). The polynomial central moment relation extends to the purely advective transport case which arises as a large-distance limit of advective–dispersive transport in parallel flow models. The associated limit g(t,x) distributions are of N-modal form and maintain constant shapes independent of travel distance. The finite-mixture framework for moment evaluation is also a potentially useful device for forecasting g(t,x) distributions, which may include multimodal forms. A synthetic example illustrates g(t,x) forecasting using a mixture of normal distributions.

text: Temporal moments of a tracer pulse in a perfectly parallel flow system Perfectly parallel groundwater transport models partition water flow into isolated one-dimensional stream tubes which maintain total spatial correlation of all properties in the direction of flow. The case is considered of the temporal moments of a conservative tracer pulse released simultaneously into N stream tubes with arbitrarily different advective–dispersive transport and steady flow speeds in each of the stream tubes. No assumptions are made about the form of the individual stream tube arrival-time distributions or about the nature of the between-stream tube variation of hydraulic conductivity and flow speeds. The tracer arrival-time distribution g(t,x) is an N-component finite-mixture distribution, with the mean and variance of each component distribution increasing in proportion to tracer travel distance x. By utilising moment relations of finite mixture distributions, it is shown (to r=4) that the rth central moment of g(t,x) is an rth order polynomial function of x or φ, where φ is mean arrival time. In particular, the variance of g(t,x) is a positive quadratic function of x or φ. This generalises the well-known quadratic variance increase for purely advective flow in parallel flow systems and allows a simple means of regression estimation of the large-distance coefficient of variation of g(t,x). The polynomial central moment relation extends to the purely advective transport case which arises as a large-distance limit of advective–dispersive transport in parallel flow models. The associated limit g(t,x) distributions are of N-modal form and maintain constant shapes independent of travel distance. The finite-mixture framework for moment evaluation is also a potentially useful device for forecasting g(t,x) distributions, which may include multimodal forms. A synthetic example illustrates g(t,x) forecasting using a mixture of normal distributions.

year: 2003-06

title: Paradoxical mobilities: sharemilking with Te Raparahi Lands Trust (Wāotū)

authors: Hutcheson, Gail Yvonne

subjects: mobilities

abstract: Mobilities are important for capturing some of the combined movements of people, animals and objects in all of their complex relational dynamics. Sharemilking involves a cascade of mobilities: from the modest journies of the everyday to the upheaval of complete farm moves. Here we examine how sharemilkers are enabled and constrained in different ways by being mobile and landless, but also included are hopeful geographies. The sharemilker's mobile relationship to land, rather than ownership of it, works well with indigenous ideas of kaitiakitanga (guardianship) that is a central feature of multiply owned Māori land trust (Te Raparahi). Combining sharemilker mobility with te Raparahi, and importantly Ngāti Hūri historical and contemporary connections to Te Wāotū in South Waikato, Aotearoa New Zealand, reveals paradoxical mobilities of place.

text: Paradoxical mobilities: sharemilking with Te Raparahi Lands Trust (Wāotū) Mobilities are important for capturing some of the combined movements of people, animals and objects in all of their complex relational dynamics. Sharemilking involves a cascade of mobilities: from the modest journies of the everyday to the upheaval of complete farm moves. Here we examine how sharemilkers are enabled and constrained in different ways by being mobile and landless, but also included are hopeful geographies. The sharemilker's mobile relationship to land, rather than ownership of it, works well with indigenous ideas of kaitiakitanga (guardianship) that is a central feature of multiply owned Māori land trust (Te Raparahi). Combining sharemilker mobility with te Raparahi, and importantly Ngāti Hūri historical and contemporary connections to Te Wāotū in South Waikato, Aotearoa New Zealand, reveals paradoxical mobilities of place.

year: 2017