Earlier researchers have produced conceptual models of Mississippi River delta plain development which divide the deltaic plain into upper and lower reaches. The upper deltaic plain has been described as an area composed mainly of lacustrine, lacustrine delta, backswamp, and crevasse channels, with minimal distributary development. The lower deltaic plain is characterized by numerous distributaries forming distributary systems and lobes. Detailed geomorphic mapping and chronologic reconstruction within the Atchafalaya Backwater Area of the upper deltaic plain of the Mississippi River has led to the recognition of a complex network of distributary development related to three distinct distributary systems that formed in the upper deltaic plain over the past 2500 years. These systems do not fit previous models of upper deltaic plain development. The East Atchafalaya Basin Protection Levee blocked Atchafalaya River water and sediment from entering the study area and burying these older distributary systems, preserving their surface expression and allowing their identification. Results show that distributary systems can be a major contributor to upper deltaic plain development and that these systems are not always related to the lower delta plain delta switching process. A stable Mississippi River position and a favorable gradient in the study area over the past 4,000 years appear to be responsible for the geomorphic development of the study area.

Magister Artium - MA / This thesis investigates the influence of climate change and climatic variability on wetland ecosystems (coastal and inland wetlands) on the Agulhas coastal plain. Firstly, this research examines coastal wetland ecosystem resilience to sea level rise by modelling sea level rise trajectories for the Droё River wetland. The rate of sediment accretion was modelled relative to IPCC sea level rise estimates for multiple RCP scenarios. For each scenario, inundation by neap and spring tide and the 2-, 4- and 8-year recurrence interval water level was modelled over a period of 200 years. When tidal variation is considered, the rate of sediment accretion exceeds rising sea levels associated with climate change, resulting in no major changes in terms of inundation. When sea level rise scenarios were modelled in conjunction with the recurrence interval water levels, flooding of the coastal wetland was much greater than current levels for the 1 in 4 and 1 in 8 year events. The study suggests that for this wetland, variability of flows may be a key factor contributing to wetland resilience. Secondly, the thesis examines the variability of open wetland water surface areas and their relation to rainfall to determine wetland hydrological inputs for the Nuwejaars wetland system and respective wetlands. A remote sensing approach was adopted, Landsat 5 TM and 8 OLI multispectral imagery were used to detect changes of water surfaces for the period 1989 to 2017. Water surfaces were enhanced and extracted using the Modified Normalized Difference Water Index of Xu (2006). The coefficient of variation of wetland water surface area was determined. The variability ranges from low to high for respective wetlands. A correlation analysis of wetland water surfaces and local and catchment rainfall for the preceding 1, 3, 6, 9, 12 and 24 months was undertaken. The preceding month and associated inputs explains the annual variability of surface waters. The study suggests that, the variability of wetland water surface area are related to variations to water inputs and groundwater, as well as variations in water outputs such as evapotranspiration and an outlet channel.

Magister Artium - MA / The thesis offers insight into English literature studies as taught at high school level to Grade 12 learners, employing Louise Rosenblatt’s reader response theory to explore and understand their encounter and engagement with prescribed poetry by enquiring as to whether social conditions in their lives allow an identification with these poems. The thesis argues for the validity and implementation of reader response theory in the South African curriculum because when learners engage with their memories, experiences and opinions; identification with the poem is possible. If learners identify with the poems that are being taught, there may be a sense of harmony as they realise that their problems or experiences are not in isolation. The sample population comprises of learners attending two high schools located in Mitchells Plain, Cape Town: a community that presents a myriad of societal challenges. Proper ethical considerations were followed in order to gain access to the research sites and anonymity was promised to all research participants. The research entails the usage of openended questionnaires to elicit data which has been processed qualitatively by means of content analysis whereby various central social environment themes were identified. A background of Mitchells Plain’s social ills is provided in order to understand the challenges facing the research participants. The thesis offers an extensive discussion on the history and current state of education in South Africa, as well as a delineation of the study of the discipline of poetry by highlighting its proposed benefits from humanities and scientific perspectives. Additionally, the thesis provides a background on different reader response theories and published reader response studies with a focus on the social environment of the individual for further elucidation of the theoretical framework. Results of the study reveal that the selected poems by William Blake, W.H. Auden, Gerard Manley Hopkins and Chinua Achebe yield fascinating responses as most research participants can socially identify with the contextual themes and characters. The thesis sheds light on a few shortcomings or limitations which may have impacted the data collection process and provides recommendations on how to improve any future related studies and possibilities of best teaching practice of English literature in South African high schools.

Magister Artium (Social Work) - MA(SW) / Substance abuse has become a serious global problem affecting individuals, families and communities. The effects of substance abuse devastate both the user and their families. This study aimed to describe the adverse effects that substance abuse has on the levels of care giving and well-being of families. The study explored family members perceptions of the ways in which an adolescent’s substance abuse affects family care giving and well-being. The study was conducted within a qualitative approach in order to gather an in depth understanding of the family’s experiences. Furthermore, the study was aligned with Family Systems and Bowens Family Theories, which served as reference points to allow the researcher to discern how substance abuse influences family roles, dynamics and functioning. The researcher used the case study design which focused on an issue of concern (such as adolescent substance abuse) and thus selected one case to elucidate the issue i.e. a single case study. The case would be the family members of substance abusing adolescents in Mitchells Plain. The population of interest were the parents and siblings of adolescents who abused substances. Purposive sampling was used to select families with participants who had the specific qualities and experiences needed for the study. The study sample consisted of 12 participants, seven parents (mothers) and five siblings. The participants were female which corresponds with literature, as females are perceived as more willing to share and speak about their experiences. Individual semi-structured interviews were used for data collection through the use of interview schedules. Data verification methods ensured credibility (member checking), transferability (using thick, rich descriptions), dependability (an inquiry audit), and confirmability (using researcher reflexivity). The data was analysed in the form of qualitative thematic analysis achieving data reduction by seeking themes, sub-themes and categories of data. Four themes emerged from the findings, namely, (1) parents/sibling reactions to discovering the substance abuse, (2) the effects of substance abuse on the parents/siblings living with a substance abuser, (3) effects on family communication, and (4) measures used to assist the substance abuser. Each theme was further delineated into 12 sub-themes and 23 categories which were based on both predefined and emergent codes. Permission to conduct this study was obtained from the university’s Faculty of Community and Health Sciences Ethics Committee by its Humanities and Social Sciences Research Ethics Committee (HSSREC); and by the Department of Social Development’s Research Ethics Committee. Ethics compliance was assured through confidentiality and privacy, securing and handling of confidential information, and debriefing opportunities to ensure that emotional harm is minimised together with sensitive interviewing techniques.

Rhyolites of the Picabo volcanic field (10.4-6.6 Ma) of the Yellowstone hotspot in eastern Idaho are preserved as thick ignimbrites and lavas along the margins of the Snake River Plain. This study presents new O and Hf isotope data and U-Pb geochronology from individual zircons, O isotope data from major phenocrysts, whole rock Sr and Nd isotope data, whole rock geochemistry, and trace element and volatile analyses of quartz-hosted melt inclusions, which were used to characterize the evolution of rhyolite generation through the eruptive sequence. The chemical composition of the first eruption of the caldera complex, the Tuff of Arbon Valley, suggests magma generation through repeated magma injection into the crust, remelting, crystallization, mixing, and crustal assimilation. Subsequent eruptions have diverse and low δ18O signatures indicating rhyolite generation through the remelting of variably hydrothermally altered volcanics, followed by rapid batch assembly. This thesis includes co-authored material previously published.

Life history exist as a set of co-adapted traits designed to solve ecological problems, and theory predicts that in unpredictable environments, these are geared towards relatively slow growth and a long reproductive lifespan with relatively few offspring per reproductive event. However, recently the response of anurans to such conditions has been controversial and little empirical data are published on the response of Australian anurans living under such conditions. Limnodynastes Tasmaniensis is a medium sized endemic frog of the family Myobatrachidae that has an extensive range that encompasses every Australian state. Limited published data indicates that intra-population variation in reproductive parameters exist in this species and therefore it is an ideal model to test life history theory under Australian conditions. A population of the species was studied within remnant woodlands of North West Sydney, Australia. Many observations were made and the results shown in some detail. The data found does not completely conform with current theory developed largely for data collected in the northern hemisphere and highlights the need for further research into life history strategies of Australian anurans. / Doctor of Philosphy (PhD)

The aims of this project were to: 1. further develop the evaluation systems of Westman (1986), Chapman and Underwood (2000) and Wilkins et al (2004) proposed for the assessment of restored ecosystems; and 2. use these developments to evaluate whether the revegetation of agricultural land on the Cumberland Plain, west of Sydney, NSW, has led to the re-establishment of a grassy woodland. The evaluation system developed in this Thesis was designed to compare three key ecosystem attributes. First, to assess how restoration was progressing, the species richness, composition and vegetation structure of abandoned pasture (starting point), was compared to that of restored vegetation of differing ages (putative mid points), and remnants (goal or end point). Refinements of the previous assessment models included formulation of predictions about native and exotic species richness and composition under the assumption that restoration was succeeding, and explicit testing of these predictions by planned comparisons and trajectory analysis of species composition. Second, the small-scale effects of planted tree canopies on species composition were assessed to test the hypothesis that native tree canopies facilitate the return of natives. Third, the effects of fire and neighbour removal on seedling emergence and establishment in pasture, restored vegetation and remnants were examined to explore what factors controlled germination and establishment. The results of this study indicate that to date, there has been a partial success of the restoration program at the study sites: while native species have returned unaided to restored sites, the trajectory of native species composition was not in the direction of remnants. There was however, increased species richness of exotic species detected underneath planted tree canopies. Patterns of seedling emergence observed in this study suggest that recruitment plays a role in the maintenance of the species composition found in restored vegetation, with seedling emergence dominated by exotics The evaluation methodology developed within this Thesis is a transparent and accurate way to measure ecological changes in vegetation that have occurred as a result of restoration.The restoration evaluation methodology further developed here will be useful to an industry that involves tree planting, landcare, revegetation and bush regeneration. It will complement guidelines provided by government and other sources that advise on practical aspects of revegetation and will be one of the few which have examined the success of revegetation in ecological terms that are founded on sound scientific basis. / Doctor of Philosophy (PhD)

Eighteen splice specimens were tested under four-point loading as part of a larger experimental investigation to study the behaviour of lap spliced plain steel bars in reinforced concrete specimens. Three of the specimens were instrumented with strain gauges adhered to the reinforcement and the concrete side face. Three lap splice lengths, two bar sizes for square bars, and one bar size for round bars were investigated. The principal reinforcement was either cast in the bottom or top position. The results of maximum loads, crack patterns, load versus deflection behaviour, and deflected profiles are presented for all specimens. The analysis of specimens with strain gauge instrumentation is also presented, and includes results of strain compatibility, bond stress distribution, and flexural section analysis. All specimens failed by bond, caused by a sudden pullout of the reinforcement within the splice region. An equivalent round diameter based upon the cross-section area of the square bars allowed for a single predictive equation between the maximum normalized load as a function of splice length, casting position and bar size. A top cast factor of 0.4 and 0.6 captures the reduction in the maximum normalized load for specimens cast with round and square bars, respectively, in the top position. The CEB-FIP Model Code (1993) predictive equations are reasonably conservative in capturing the behaviour of specimens reinforced with round bars cast in the bottom position, and square bars with side dimension of 25 mm cast in the bottom position. However, the CEB-FIP Model Code (1993) predictive equation is unconservative when predicting the behaviour of specimens reinforced with either square or round bars cast in the top position. On the other hand, the draft CEB-FIP Model Code (2010) provisions showed an overly conservative prediction for all specimens reinforced with either round or square bars cast in the top or bottom position. Instrumented specimens showed that strain compatibility between the longitudinal reinforcement and the surrounding concrete did not exist for much of the loading range due to bond loss. The evaluation of the neutral axis location within the shear span showed that shear is first transferred by beam action, followed by arch action. The use of three strain gauges adhered to the concrete side face provided flexural moments similar to that predicted theoretically.

Fifteen splice specimens reinforced with plain steel bars, including three specimens instrumented with both steel and concrete strain gauges, were tested under monotonically applied four-point loading to develop a database of reliable bond test results and contribute to the development of a reliability based bond provision for plain steel bars to evaluate historical concrete structures. The maximum applied load for the specimens and their observed failure behaviour are reported. In addition to that, a strain compatibility analysis, average bond stress distribution, and flexural section analysis within the lap splice length of the instrumented specimens are also reported.<p> All of the specimens failed in bond within the lap splice length. The load capacity of two specimens reinforced with plain steel bars was 60% of the reported load resistance of specimens with identical geometry and reinforced with deformed bars. The CEB-FIP Model Code provisions for average bond stress of plain steel bars underestimated the maximum applied load recorded for the tested specimens by 16% on average. An empirically derived equation to predict the bond capacity of plain steel bars was determined to be proportional to both the splice length and the nominal bar diameter. <p> Observed cracks in the shear spans remained vertical and suggest the development of arch action within this region. The formation of a large crack at one end of the lap splice length and a review of the load versus deflection behaviour indicated a sudden bond failure of the specimens. Removal of concrete cover at the ends of the lap splice length following testing of the specimens showed evidence of slip of the lapped bars.<p> Instrumented splice specimens provided evidence of bond loss within the lap splice region. As-measured steel strains were higher than those measured for the surrounding concrete due to a loss of strain compatibility. The average bond stress distribution within the lap splice length became more uniform as the applied load approached the maximum applied load. The flexural analysis calculated based on concrete strains above the neutral axis and steel strain provided a reasonable estimate of specimen capacity.

Fifteen splice specimens reinforced with plain steel bars, including three specimens instrumented with both steel and concrete strain gauges, were tested under monotonically applied four-point loading to develop a database of reliable bond test results and contribute to the development of a reliability based bond provision for plain steel bars to evaluate historical concrete structures. The maximum applied load for the specimens and their observed failure behaviour are reported. In addition to that, a strain compatibility analysis, average bond stress distribution, and flexural section analysis within the lap splice length of the instrumented specimens are also reported.<p> All of the specimens failed in bond within the lap splice length. The load capacity of two specimens reinforced with plain steel bars was 60% of the reported load resistance of specimens with identical geometry and reinforced with deformed bars. The CEB-FIP Model Code provisions for average bond stress of plain steel bars underestimated the maximum applied load recorded for the tested specimens by 16% on average. An empirically derived equation to predict the bond capacity of plain steel bars was determined to be proportional to both the splice length and the nominal bar diameter. <p> Observed cracks in the shear spans remained vertical and suggest the development of arch action within this region. The formation of a large crack at one end of the lap splice length and a review of the load versus deflection behaviour indicated a sudden bond failure of the specimens. Removal of concrete cover at the ends of the lap splice length following testing of the specimens showed evidence of slip of the lapped bars.<p> Instrumented splice specimens provided evidence of bond loss within the lap splice region. As-measured steel strains were higher than those measured for the surrounding concrete due to a loss of strain compatibility. The average bond stress distribution within the lap splice length became more uniform as the applied load approached the maximum applied load. The flexural analysis calculated based on concrete strains above the neutral axis and steel strain provided a reasonable estimate of specimen capacity.