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: The political economy of intrastate armed conflicts: The feasibility hypothesis in the case of Pakistan

authors: Maqbool, Muhammad Yahhya

subjects: political science

abstract: This thesis examines the structural conditions that make intrastate armed conflict feasible in Pakistan. While much of the existing literature attributes Pakistan’s internal conflicts to ideology, identity, or historical grievances, this study argues that such explanations account for the framing and mobilisation of conflict but fail to explain why violence clusters in specific regions despite similar grievances elsewhere, and why multiple groups with varied motivations operate from the same locations. Addressing this conceptual gap, the thesis employs the feasibility hypothesis as its theoretical lens, which posits that sustained rebellion becomes possible where it is operationally and economically viable.
The central research question asks whether operational and economic feasibility better explains Pakistan’s conflict dynamics than ideational or grievance-based accounts. The study adopts a mixed-methods design. The quantitative analysis uses district-level cross-sectional data to test the statistical association of six independent variables (terrain ruggedness, road density, border proximity, human development, poverty, and natural resources) with conflict intensity. This is complemented by qualitative analysis of secondary literature, policy reports, and historical narratives to interpret and contextualise the empirical results.
The findings confirm that rugged terrain, proximity to porous borders (especially with Afghanistan and Iran), and low human development are significantly associated with higher conflict intensity. By contrast, poverty and road density show weak or insignificant effects, while natural resources influence conflict primarily through enabling illicit economies. These results support the argument that intrastate armed conflict persists where structural conditions make rebellion operationally and economically feasible.
Theoretically, the study localises and refines the feasibility hypothesis for sub-national analysis using improved operational proxies. Methodologically, it contributes through a mixed-methods framework linking quantitative modelling and contextual qualitative interpretation. Policy-wise, it recommends strengthening border management, improving local governance, and investing in human development to mitigate structural enablers of violence. The findings advance comparative research on the political economy of conflict by demonstrating how structural feasibility, rather than ideology alone, shapes the geography of rebellion in fragile states.

text: The political economy of intrastate armed conflicts: The feasibility hypothesis in the case of Pakistan This thesis examines the structural conditions that make intrastate armed conflict feasible in Pakistan. While much of the existing literature attributes Pakistan’s internal conflicts to ideology, identity, or historical grievances, this study argues that such explanations account for the framing and mobilisation of conflict but fail to explain why violence clusters in specific regions despite similar grievances elsewhere, and why multiple groups with varied motivations operate from the same locations. Addressing this conceptual gap, the thesis employs the feasibility hypothesis as its theoretical lens, which posits that sustained rebellion becomes possible where it is operationally and economically viable.
The central research question asks whether operational and economic feasibility better explains Pakistan’s conflict dynamics than ideational or grievance-based accounts. The study adopts a mixed-methods design. The quantitative analysis uses district-level cross-sectional data to test the statistical association of six independent variables (terrain ruggedness, road density, border proximity, human development, poverty, and natural resources) with conflict intensity. This is complemented by qualitative analysis of secondary literature, policy reports, and historical narratives to interpret and contextualise the empirical results.
The findings confirm that rugged terrain, proximity to porous borders (especially with Afghanistan and Iran), and low human development are significantly associated with higher conflict intensity. By contrast, poverty and road density show weak or insignificant effects, while natural resources influence conflict primarily through enabling illicit economies. These results support the argument that intrastate armed conflict persists where structural conditions make rebellion operationally and economically feasible.
Theoretically, the study localises and refines the feasibility hypothesis for sub-national analysis using improved operational proxies. Methodologically, it contributes through a mixed-methods framework linking quantitative modelling and contextual qualitative interpretation. Policy-wise, it recommends strengthening border management, improving local governance, and investing in human development to mitigate structural enablers of violence. The findings advance comparative research on the political economy of conflict by demonstrating how structural feasibility, rather than ideology alone, shapes the geography of rebellion in fragile states.

year: 2025-10-22

title: Maori perspectives of the environment: A review of Environment Waikato iwi environmental management plans.

authors: Whangapirita, Laura

subjects: Maori

abstract: The purpose of this report is to gather, summarise, analyse and distribute information held by Environment Waikato on Maori and the environment. To achieve this we evaluated and summarised the Ngaati Te Ata Iwi Policy Statement, Iwi Environmental management Plans and iwi contributions made toward the Proposed Waikato Regional Plan (1998) using a Maori values framework. This report has been prepared to contribute towards developing a resource for Environment Waikato’s Strategic Plan Review Teams. The report itself refers to values and beliefs sourced from iwi documents held by Environment waiakto and are presented using a Maori values framework providing the reader with an introduction to the environmental perspectives of tangat whenua in  the Waikato region.

text: Maori perspectives of the environment: A review of Environment Waikato iwi environmental management plans. The purpose of this report is to gather, summarise, analyse and distribute information held by Environment Waikato on Maori and the environment. To achieve this we evaluated and summarised the Ngaati Te Ata Iwi Policy Statement, Iwi Environmental management Plans and iwi contributions made toward the Proposed Waikato Regional Plan (1998) using a Maori values framework. This report has been prepared to contribute towards developing a resource for Environment Waikato’s Strategic Plan Review Teams. The report itself refers to values and beliefs sourced from iwi documents held by Environment waiakto and are presented using a Maori values framework providing the reader with an introduction to the environmental perspectives of tangat whenua in  the Waikato region.

year: 2003-09