Science Collected Works - Theses
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ItemLandslides of the Lance Creek catchment, South Gippsland Hills, Victoria(University of Melbourne, 2001)This study aimed to achieve three objectives: 1) to examine the mechanism and various factors contributing to landsliding, 2) to determine criteria for identifying landslide prone areas, and 3) to suggest guidelines for minimizing the incidence oflandslides. The Lance Creek catchment study area is located in the foothills of the South Gippsland Hills, approximately 200 km southeast from Melbourne, and covers about 13 km2 � In order to achieve the objectives, the study has involved collection and analysis of multiple sets of data: geology, topography, climate, and land use, etc.; farmer interviews, regional mapping of landslides, morphology mapping of landslides; rock, soil and water sampling; perched water and landslide activity monitoring; petrological analysis, rock property tests, .X.R.D. analysis of clay mineralogy, soil triaxial tests and water TDS analysis. This study has identified that slump (involving soil and rock) and earthflow (involving soil) are the two main types of landslides in the study area. The main features of a slump are a main scarp, a head scarp, minor scarps, cracks, ponds, springs and a bulging mass. Slumps are likely to occur on moderately steep to steep (8�-22�) slopes of concave shape of north-west, north, north-east and south-east facing. The main features of an earthflow are a main scarp, minor scarps and a bulging mass. Earthflows are likely to occur on steep (??5�) slopes of convex shape of north-west, north and north east facing. This study has found that there were few landslides before land clearance; over 98% of landslides investigated have happened after land clearance ( <66 years). All landslides have been triggered by severe rainstorm events. This study has also found that the factors controlling landslides of the Lower Cretaceous Strzelecki Group sandstone and mudstone of the study area are rock weathering, geological structure, climate and topography, drainage, land clearance, stock grazing, farm track construction and farm dam construction. Slope of concave shape and bedding dipping coinciding with slope facing are the primary assessment factors of occurrence of slumps. Slope of convex shape is the primary assessment factor of occurrence of earthflows. Angle of slope, aspect of slope, drainage, trees, stock grazing, track and dam are the secondary assessment factors of occurrence for both slumps and earthflows. Subsurface drainage, surface drainage and tree planting are suggested remediation methods for minimizing landsliding. Among these, subsurface drainage is the most efficient. Tree planting is efficient in stabilizing earthflows and small slumps but not for medium and large slumps. Stock should not graze on landslides, slopes with tension cracking, steep (^5�) convex slopes of north-west, north and north-east facing, narrow steep convex slopes between two farm tracks and stream banks. Farm track construction should be discouraged on moderately steep to steep slopes of concave shape with bedding dipping coinciding with slope facing north-west, north, north-east and south-east, or steep convex slopes of north-west, north and north east facing. Farm dam construction should avoid the head of old slips, slips and areas experiencing recent movements.
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ItemMagnetic and gravitational investigation of the Douglas depression surrounding Mitre Lake, Western Victoria(University of Melbourne, 2001)Gravity and magnetic geophysical surveying techniques were applied to the study of the Douglas Depression to investigate the boundaries of the depression as determined in previous studies. Lines of both types of data were run in a north-south direction on both the eastern and western sides of Mitre Lake. The magnetic signature of the basement geology (at a depth of approximately 120m) overprinted any weak signals from the surfical geology. The gravity data revealed the presence of an incised channel within the Douglas Depression, that appears to correlate with the locations of the surface lakes, which aligned with the radiometrics data over the area. However, further investigation is required to confirm this.
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ItemPhylogeny and biogeography of section Botrycephalae (Acacia subgenus Phyllodineae)(University of Melbourne, 2000)Section Botrycephalae (Acacia subgenus Phyllodineae) comprises approximately 40 specific and infraspecific taxa. The section is restricted to South Eastern Australia, extending from South Eastern Queensland to Tasmania and the south eastern part of South Australia. The section is characterized by adult plants retaining bipinnate leaves, stipules not spinescent and capitulate inflorescences arranged in racemes. The sister group to the Botrycephalae is section Phyllodineae, including Acacia podalyriifolia and A. ligulata, which form a monophyletic group (Chappill and Maslin, 1995). These species and A. calamifolia (Phyllodineae) were used as outgroups for a phylogenetic analysis of the Botrycephalae. The cladistic analysis was based on a data set of morphological, anatomical and seedling characters, using parsimony methods. Both qualitative and quantitative characters were coded. Most of the multistate characters were treated as ordered characters to allow linear transformation with states of equal value. Some characters were not variable across the section and other characters showed a high level of homoplasy. Due to the predominance of quantitative data, a phenetic analysis was also conducted for the ingroup taxa using the same data set as in the cladistic analysis. Although relationships within section Botrycephalae were not fully resolved, some subclades were defined with confidence (well-supported by jackknife values). A provisional infrasection classification of the Botrycephalae is proposed. Based on the phylogenetic analysis three series and six subseries are recognised. Those three series are Latisepalinae, Fulvinae and Mearnsinae. Series Latisepalinae, including subseries Elatae, Pruinosae and Decurrenae, is not monophyletic and includes taxa that formed unresolved basal nodes in the cladograms; it requires further analysis using molecular data. Series Fulvinae comprises three species: A. silvestris, A. fulva and A. mollifolia. Approximately half of the members of the section are included in the series Mearnsinae which, is further divided into three subseries: Jonesiae, Mearnsiae and Deaneae. The taxon cladogram was also used to analyse historical area relationships within eastern Australia. The method of sub-tree analysis (using the program TASS, Nelson and Ladiges, 1995) was employed. The biogeographic pattern suggested that some speciation relates to vicariance events but that the present distribution of some species is also due to dispersal.