title: Developing a new numerical surface/subsurface model for irrigation and drainage system design

authors: Shokri, Ali

subjects: Science & Technology

abstract: In recent decades many hydrologists have focused on surface/subsurface interactions and a number of numerical and physical models have been developed for simulating the interplay of flows between the saturated and unsaturated zones. This paper presents a numerical surface/subsurface flow model based on  2-D shallow water and 2-D Manning equations for surface flow, with 3-D Richards equations for subsurface flow in the unsaturated and saturated zones. The aim here is to provide a tool for designing more robust agricultural irrigation and drainage schemes. The model can be used in place of the classical design methods based on 1-D equations. The proposed model yields information about the water table location, depth of surface water, and water content in the unsaturated soil in any field location before and after spreading irrigation and drainage. The additional information has the possibility of decreasing expense and increasing the safety factor for both irrigation and drainage projects.

text: Developing a new numerical surface/subsurface model for irrigation and drainage system design In recent decades many hydrologists have focused on surface/subsurface interactions and a number of numerical and physical models have been developed for simulating the interplay of flows between the saturated and unsaturated zones. This paper presents a numerical surface/subsurface flow model based on  2-D shallow water and 2-D Manning equations for surface flow, with 3-D Richards equations for subsurface flow in the unsaturated and saturated zones. The aim here is to provide a tool for designing more robust agricultural irrigation and drainage schemes. The model can be used in place of the classical design methods based on 1-D equations. The proposed model yields information about the water table location, depth of surface water, and water content in the unsaturated soil in any field location before and after spreading irrigation and drainage. The additional information has the possibility of decreasing expense and increasing the safety factor for both irrigation and drainage projects.

year: 2011-01-01

title: Cognitive genre prototype modelling and its implications for the teaching of academic writing to learners of English as a second language

authors: Bruce, Ian

abstract: The overall aim of this research project is to identify and analyse recurring prototypical discourse patterns in academic writing in English in order to inform the teaching of writing for academic purposes to non English-speaking background (NESB) students. 

Chapter 1 presents the motivation for the thesis, and outlines the aims, objectives, and research methods. Two concepts for the classification of discourse are proposed cognitive genre and social genre. In relation to the former, four prototypes (termed Rhetorical Types), characteristic of written academic discourse, are identified. 

Chapter 2 reviews a number of approaches to the categorisation of discourse, beginning with classical rhetoric, and tracing the progress of discourse-classification constructs over time, focusing primarily on cognitive rather than social genre.

Chapter 3 critically reviews recent pedagogic approaches to the classification of extended written discourse in terms of social genre. These focus, at a macro-level, on overall organisational structure and, at a micro-level, on linguistic features. It is concluded that any adequate construct for classifying extended written discourse also needs to involve cognitive frameworks that organise knowledge (see Chapter 4).

Chapter 4 reviews cognitive approaches to the classification of knowledge and seeks to establish the centrality of knowledge-organising prototypes and prototype-internal, procedural knowledge and to relate these to the cognitive organisation of written discourse.

Chapter 5 proposes a cognitive model for the organisation of procedural knowledge in written academic discourse in English. On the basis of this model, four types of cognitive genre (referred to here as Rhetorical Types) commonly drawn upon in the structuring of academic discourse are discussed. They are: Report, Explanation, Recount, and Discussion. The relationship between the Rhetorical Type construct (as a cognitive genre) and the concept of social genre is also discussed.

Chapter 6 examines each aspect of the Rhetorical Type model proposed earlier (see Chapter 5) in terms of its occurrence in a corpus of academic texts and by reference to sample texts from the corpus. 

Chapter 7 reports on two studies. The first involves examining samples of native-speaker and non-native-speaker writing in terms of the model proposed in Chapters 5 and 6. In the second, the model ratings of a small number of scripts (from the first study) are compared with grades assigned to the same scripts by two expert raters unfamiliar with the model.

Chapter 8 provides an overview of the research, and discusses its implications for the teaching and learning of English as a second language.

text: Cognitive genre prototype modelling and its implications for the teaching of academic writing to learners of English as a second language The overall aim of this research project is to identify and analyse recurring prototypical discourse patterns in academic writing in English in order to inform the teaching of writing for academic purposes to non English-speaking background (NESB) students. 

Chapter 1 presents the motivation for the thesis, and outlines the aims, objectives, and research methods. Two concepts for the classification of discourse are proposed cognitive genre and social genre. In relation to the former, four prototypes (termed Rhetorical Types), characteristic of written academic discourse, are identified. 

Chapter 2 reviews a number of approaches to the categorisation of discourse, beginning with classical rhetoric, and tracing the progress of discourse-classification constructs over time, focusing primarily on cognitive rather than social genre.

Chapter 3 critically reviews recent pedagogic approaches to the classification of extended written discourse in terms of social genre. These focus, at a macro-level, on overall organisational structure and, at a micro-level, on linguistic features. It is concluded that any adequate construct for classifying extended written discourse also needs to involve cognitive frameworks that organise knowledge (see Chapter 4).

Chapter 4 reviews cognitive approaches to the classification of knowledge and seeks to establish the centrality of knowledge-organising prototypes and prototype-internal, procedural knowledge and to relate these to the cognitive organisation of written discourse.

Chapter 5 proposes a cognitive model for the organisation of procedural knowledge in written academic discourse in English. On the basis of this model, four types of cognitive genre (referred to here as Rhetorical Types) commonly drawn upon in the structuring of academic discourse are discussed. They are: Report, Explanation, Recount, and Discussion. The relationship between the Rhetorical Type construct (as a cognitive genre) and the concept of social genre is also discussed.

Chapter 6 examines each aspect of the Rhetorical Type model proposed earlier (see Chapter 5) in terms of its occurrence in a corpus of academic texts and by reference to sample texts from the corpus. 

Chapter 7 reports on two studies. The first involves examining samples of native-speaker and non-native-speaker writing in terms of the model proposed in Chapters 5 and 6. In the second, the model ratings of a small number of scripts (from the first study) are compared with grades assigned to the same scripts by two expert raters unfamiliar with the model.

Chapter 8 provides an overview of the research, and discusses its implications for the teaching and learning of English as a second language.

year: 2003

title: The influence of harvest frequency and regime on the performance of  Filamentous Algae Nutrient Scrubbers treating agricultural drainage

authors: Waaka, Okeroa

subjects: Filamentous algae nutrient scrubbers

abstract: Filamentous algae nutrient scrubbers (FANS) are ecologically engineered flow-ways that have recently been proposed as a potential on-farm method to treat agricultural drainage in New Zealand. The effectiveness of FANS systems to remove nutrients from polluted waters and to produce algal biomass as a harvestable by-product is heavily influenced by operational parameters. As filamentous algae grow on a flow-way, the thickness of the algal biomass increases and begins to reduce light penetration and nutrient assimilation. Therefore, periodic harvesting of the accumulated algal biomass plays a key role in determining the biomass production and nutrient removal performance of FANS systems. 

The overall aim of this study was to investigate the influence of harvest frequency and harvest regime on biomass productivity and nutrient removal of an outdoor FANS system. The FANS system used in this study consisted of six flow-ways that were split into two sets of triplicate flow-ways named “FULL” and “PARTIAL”. Harvesting of the FULL replicate flow-ways occurred once a week, where algal biomass accumulated along the entirety of the flow-way was collected. Harvesting of the PARTIAL replicate flow-ways occurred twice a week, where the algal biomass was collected in alternate meter sections (a total of 3-metre harvest length every 3 – 3.5 days). 

The increased harvest frequency (3 – 3.5 days) and sectioned harvest regime implemented in the PARTIAL replicate flow-ways significantly improved biomass productivity (3.2 g DW m-2. d) in comparison to the less frequent (7 – 7.5 days) and total harvest regime implemented in the FULL replicate flow-ways (0.9 g DW m-2. d). However, there was no significant difference in nutrient removal rates between the PARTIAL and FULL replicate flow-ways. There is still limited understanding of how operational parameters can be optimized to maximise biomass productivity and nutrient removal in FANS systems on a year-round basis. However, the findings of this study demonstrate that an increased harvest frequency and sectioned harvest regime can improve the biomass yield of filamentous algae grown on an outdoor FANS system during spring to summer months. 

Furthermore, this study has suggested the potential for Māori acceptance of FANS technology and algal biomass use. In person interviews with whanau and iwi members recalled use of algal biomass harvested from rivers and streams as fertilizer for vegetable gardens or bait for eel trapping. Moreover, the literature review and in person interviews highlighted the importance of identifying and using ngā kupu (words and terms) used by Māori to describe freshwater algae. The intergenerational observation and utilization of algae as a resource by Māori may reveal an awareness of biological processes that either differs or compliments a Western Science point of view. Incorporating this knowledge into current water and environmental management practices could be extremely beneficial for improving water quality of streams in Aotearoa New Zealand.

text: The influence of harvest frequency and regime on the performance of  Filamentous Algae Nutrient Scrubbers treating agricultural drainage Filamentous algae nutrient scrubbers (FANS) are ecologically engineered flow-ways that have recently been proposed as a potential on-farm method to treat agricultural drainage in New Zealand. The effectiveness of FANS systems to remove nutrients from polluted waters and to produce algal biomass as a harvestable by-product is heavily influenced by operational parameters. As filamentous algae grow on a flow-way, the thickness of the algal biomass increases and begins to reduce light penetration and nutrient assimilation. Therefore, periodic harvesting of the accumulated algal biomass plays a key role in determining the biomass production and nutrient removal performance of FANS systems. 

The overall aim of this study was to investigate the influence of harvest frequency and harvest regime on biomass productivity and nutrient removal of an outdoor FANS system. The FANS system used in this study consisted of six flow-ways that were split into two sets of triplicate flow-ways named “FULL” and “PARTIAL”. Harvesting of the FULL replicate flow-ways occurred once a week, where algal biomass accumulated along the entirety of the flow-way was collected. Harvesting of the PARTIAL replicate flow-ways occurred twice a week, where the algal biomass was collected in alternate meter sections (a total of 3-metre harvest length every 3 – 3.5 days). 

The increased harvest frequency (3 – 3.5 days) and sectioned harvest regime implemented in the PARTIAL replicate flow-ways significantly improved biomass productivity (3.2 g DW m-2. d) in comparison to the less frequent (7 – 7.5 days) and total harvest regime implemented in the FULL replicate flow-ways (0.9 g DW m-2. d). However, there was no significant difference in nutrient removal rates between the PARTIAL and FULL replicate flow-ways. There is still limited understanding of how operational parameters can be optimized to maximise biomass productivity and nutrient removal in FANS systems on a year-round basis. However, the findings of this study demonstrate that an increased harvest frequency and sectioned harvest regime can improve the biomass yield of filamentous algae grown on an outdoor FANS system during spring to summer months. 

Furthermore, this study has suggested the potential for Māori acceptance of FANS technology and algal biomass use. In person interviews with whanau and iwi members recalled use of algal biomass harvested from rivers and streams as fertilizer for vegetable gardens or bait for eel trapping. Moreover, the literature review and in person interviews highlighted the importance of identifying and using ngā kupu (words and terms) used by Māori to describe freshwater algae. The intergenerational observation and utilization of algae as a resource by Māori may reveal an awareness of biological processes that either differs or compliments a Western Science point of view. Incorporating this knowledge into current water and environmental management practices could be extremely beneficial for improving water quality of streams in Aotearoa New Zealand.

year: 2023