School of Earth Sciences - Theses
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ItemAltitudinal distribution of vegetation in the headwaters of the Wongungarra River, Victoria( 1993)Changes in vegetation composition with respect to altitude were investigated in the sclerophyllous forests of the Australian mountain region. Vegetation was surveyed at 148 sites along two transects which were located to maximise variation in altitude and minimise the influence of environmental factors not directly related to altitude. The measurement, simulation, and estimation of environmental variables revealed that this aim was met except at the end-points of the transects where secondary influences are present.
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ItemLeachate chemistry of two modern municipal waste landfills in Melbourne, Victoria( 1999-11)This study investigates the occurrence and chemical composition of leachate at Clayton South and Brooklyn Municipal waste landfills in Melbourne, Victoria. Both are ‘modern’ municipal waste landfills, being engineered and managed consistent with current regulatory requirements. These landfills accept only putrescible and solid inert waste, but not soluble chemical, hazardous, liquid or prescribed industrial waste. (For complete abstract open document) Analyses of an extensive range of chemical parameters reveals a complex mixture of inorganic and organic compounds, similar to those of international authors researching leachate chemistry. Dominant ions in these leachates are NH4+, Na+, HC03- and Cl-. Except for Fe, heavy metals are not present in significant concentrations (mostly
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ItemOccurrence of nitrate in soil and groundwater in the Corangamite area, Western Victoria( 1996)Soil and groundwater samples taken from two areas of different land use in the Corangamite Region, 200 km west of Melbourne, were analysed for nitrate and ammonium, and in some cases chloride. Both sites are located on the Later Newer Volcanics 'stone rises', and groundwater was sampled from nested bores which intersect the shallow unconfined aquifer and deeper semi-confined aquifer at both sites. The Carpendeit site is an area of native Eucalypt forest, and the Purrumbete North site is a pasture for grazing dairy cows. Low concentrations of nitrate (< 1 mgN/L) in groundwater at Carpendeit correspond to low soil nitrate concentrations (< 3 µgN/cm3 ). Higher groundwater nitrate concentrations occurred in the shallow unconfined aquifer at Purrumbete North, (up to 3 mgN/L), but not in the lower semi-confined aquifer, and corresponds to higher nitrate concentrations in soil (1 to 60 µgN/cm3 ). Elevated nitrate concentrations also occurred in groundwater discharge at McVeans Springs, in the range 2.61 to 4.72 mgN/L, and at Ettrick Springs in the range 8.08 to 16.07 mgN/L, greater than the limit of 10 mgN/L for drinking water specified in ANZECC water quality guidelines. Nitrate in soil under the pasture is probably derived primarily from the activity of nitrogen fixing bacteria associated with subterranean clover introduced to the pasture. Soil nitrate distributions suggest intense return of nitrogen in dung and urea occurs at 'camps' locations on the pasture, where cows tend to gather for shelter. Transport of nitrogen to shallow groundwater is stimulated by cracks and channels in the basalt clay soils. Local groundwater flow includes interaction with the many lakes and temporary ponds 'which form in surface depressions at times of high rainfall. The ponds probably serve as an effective nitrate supply in recharge to the shallow aquifer.
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ItemTransport, attenuation, and degradation of organic chemicals in a basaltic aquifer system near Melbourne, Australia( 1996)Groundwater in the Pliocene to Pleistocene fractured and jointed Newer Volcanics basaltic aquifer system beneath Melbourne's industrialised western suburbs is extensively contaminated by a wide variety of organic and inorganic compounds. Groundwater in Tertiary sediments underlying the Newer Volcanics is probably also contaminated by the same sources. The main objectives of this research were 1) to assess the types, concentrations, and distribution of contaminants in the Newer Volcanics aquifer system in Melbourne's western suburbs and at a selected contaminated site and 2) to determine contaminant transport, attenuation, and degradation processes affecting organic contaminants in this aquifer system. Contaminants detected in the Newer Volcanics aquifer system during this research include phenols, volatile organic compounds, polynuclear aromatic hydrocarbons, polychlorinated biphenyls, metals, and inorganic anions. The groundwater flow system in the study area comprises a single heterogeneous and anisotropic unconfined aquifer, and includes both the Newer Volcanics and underlying sedimentary units (the Brighton Group and the Werribee Formation), although hydraulic connection of these units to the volcanics is irregular. Groundwater flow in the Newer Volcanics is through vesicular and/or scoriaceous lava flow tops and bottoms, in intercalated fluvial deposits, and through the fractured and jointed lava flows. Locally (scale of less than I km square), the basaltic aquifer system may consist of hydraulically separated shallow and deep aquifer zones that are connected on a larger scale. The deep aquifer zones may be semi-confined to confined. Groundwater in the study area is recharged via throughflow from upgradient and infiltration of rainfall. Discharge from the Newer Volcanics in the study area is primarily to underlying sedimentary formations, but also to surface water features and directly to Port Phillip Bay. Several mechanisms which reduce contaminant concentrations are possible in the Newer Volcanics aquifer system. These include volatilisation, dispersion and diffusion, transient storage, matrix diffusion, sorption, hydrolysis, and biodegradation. However, the nature of porosity in the Newer Volcanics may significantly extend the lifetime of contaminant plumes via the processes of transient storage and matrix diffusion. The primary mechanisms of attenuation and degradation of organic contaminants in the Newer Volcanics aquifer system are probably biodegradation, matrix diffusion, sorption, and dispersion (for non-reactive contaminants) in order of decreasing effect. Biodegradation at the water table and discharge areas will also be significant because of atmospheric contact and increased dissolved oxygen concentrations. Because of the relative lack of organic carbon in the basaltic aquifer system, sorption will occur mainly to mineral surfaces in clay-rich zones and within the rock matrix (concurrent with matrix diffusion). In some cases, relatively undiluted contaminants may be transported along preferred flow paths to discharge locations where they may pose a potential threat to the environment prior to degradation or attenuation. It was found, at least with phenols and volatile organic compounds in groundwater at a study site, that contaminants are degraded and/or attenuated rapidly, probably via biodegradation, matrix diffusion, and sorption. Biodegradation testing of groundwater at this study site confirmed the existence of microorganisms in the aquifer system capable of aerobic degradation; indirect evidence may indicate the presence of anaerobes.
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ItemTectonic geomorphology of the Bogong and Dargo High Plains region, east Victorian highlands, Australia( 1999)The Australian Alps, a sub-region of the Australian Eastern Highlands, have enigmatically high elevations of relief for a highland belt renowned for its ancient origins and landscapes. In debates over the Eastern Highlands history, the development and significance of the Alps have been under-represented. This study defines the morphological extent of the Australian Alps and investigates their tectonic and erosional development. The focus of investigation is the Bogong and Dargo High Plains area and the broader surrounding highlands region. The Cainozoic history of this area has not been investigated in detail since last century. The geological record of the region has substantial gaps, and the erosional history is the main indicator of tectonic change. A methodological structure different to traditional approaches is devised for this study. Cause and response are compared on a process geomorphology basis. Causes investigated are (1) intra-highland tectonics and (2) basin tectonics and sea level change. Denudational relief change is the main response investigated. Spinal and temporal comparison of quantitative results enables relationships to be determined. Peak height distribution and relief observations are used to define the morphological context of the Australian Alps. Within the Alps, the high plains area is used as a case study. Tectonic constructional morphology is investigated using peak height distributions, lineament analysis, tectonic landforms and lava offsets. A Cainozoic fault block is identified, and reactivated fault displacements are determined for bounding and intra-block faults. The erosional development of the area is determined and compared with the constructional morphology results. The sub-volcanic relief of the Bogong Volcanic Province is mapped and compared with post-volcanic stream incision. Guidelines are established for interpreting strath terraces and strath terrace long profiles are used to reconstruct the post-volcanic stream erosion development. Sources and magnitudes of oversteepened stream reaches in the present rivers are identified. Spatial and temporal relationships between fault reactivation and stream incision are determined, and the relative roles of active and passive tectonics are assessed. The tectonic and erosional development of the fault block is reconstructed in cross-sectional form. Finally, the proportion and nature of highland margin-derived stream incision is identified. This study finds that the Australian Alps were substantially affected by fault block uplift during Oligocene, with more minor phases in the Miocene and Pliocene. Broader highland margin warping accompanied fault block uplift. Uplift amounts varied between 150m and over 1000m according to proximity to major faults. Stream incision was upstream-increasing and periodic, with three incision phases during the Oligocene and Pliocene. The later phases include a possible isostatic rebound component. An additional incision phase unrelated to uplift occurred in the Gippsland Basin catchment during the Quaternary. The Australian Alps is delineated here as a separate entity within the Eastern Highlands, with its own tectonic history. Cainozoic uplift created the higher elevations and greater relief of the Alps. This history is not representative of the Eastern Highlands generally, and it should not be used as a guide to a ‘united’ Eastern Highlands uplift. The highlands consist of a ‘patchwork’ of landscape evolution scenarios, rather than a single tectonic province. More definable tectonic histories can be derived from erosional regions of geologically unrecorded time using a process geomorphology perspective. This study provides a suggested step towards redressing interpretation problems recognised in landscape evolution studies generally.