Infrastructure Engineering - Theses
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ItemModelling the seasonal variation of groundwater recharge and yield of the Barwon Downs aquifer, south-western Victoria( 1996)The Barwon Downs Aquifer in south western Victoria has long been recognized to have extensive groundwater resources. It is also an important source of supply in Barwon Water's drought emergency management plan. An understanding of the aquifer behaviour in relation to its recharge and withdrawal rates is essential for sustainable development. The main aim of this modelling exercise is to evaluate the present groundwater use and estimate the maximum possible extraction from the aquifer without serious consequences, and hence evaluate the groundwater management options and possible augmentation of the Barwon Downs Wellfield. A 2-layer finite difference model is used in groundwater modelling, and a simple hydrologic model is used to estimate the groundwater recharge. The hydrologic and groundwater models were calibrated against potentiometric heads at 38 locations. Although further effort could improve the calibration results, the model calibration is deemed sufficient for the purpose of this study. In general the potentiometric heads simulated by this groundwater model are within 2 m of the recorded heads. The calibrated model has been used to investigate groundwater extraction under various options. The model suggests that continued withdrawal of 8,000 ML/year for 10 years may not be sustainable. However, continued withdrawal of 12,600 ML/year for a period of one or two years during drought is sustainable. The model further shows that a maximum emergency extraction of up to 40,000 ML/year over a one-year period may be sustainable provided that the wells are left to recover for a period of at least 10 years. The groundwater resources thus appear to be best limited to conjunctive use with surface water during droughts. The hydrologic model also estimates that the recharge rate to the aquifer is about 9% of the total rainfall, and that to the overlying layer is about 3% of the total rainfall.
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ItemDrawdown and river bank stability( 1999-05)Drawdown is the lowering of the water level, and can refer to the groundwater, or the level of a river. In this thesis it will generally refer to a river going from a high flow condition to a lower flow condition. The rate of drawdown is expressed as either the change in flow per unit time, or the change in stage per unit time. The later is of most importance in terms of bank stability. It is commonly thought that 'rapid' drawdown of river levels adversely affects river bank stability. This concern over river banks stems largely from work done following the failures of some earth dams once the storage had been drawn down. Little further work has been done in looking at whether the same approach can be used for assessing the likely impact of drawdown on river banks. Given this apparent lack of information and knowledge on drawdown failures, this work investigated the effect of drawdown rates on river bank stability, and in so doing a better understanding of the key parameters is gained. The task was approached from three angles. The first was an analysis of the historical records to see what the rates of fall prior to regulation were, and whether they had changed since regulation. The results indicated that it can not be shown conclusively that the rate of draw down has increased since regulation. They also show that there has been a marked change in the frequency at which drawdown events of a given size occur, particularly the high incidence of lower drawdown rates. The second approach to the investigation was the field work component. The focus of the field work was the response of the near bank watertable to changes in river level. Other data collected were soil particle size distribution, bank profile monitoring (through the use of photogrammetry) and permeability testing. The results of this work show that the near bank watertable was easily able to match the rate of drawdown seen in the river channel. The particle size analysis and permeability data confirm this observation. The third prong was the smallest and consisted of some very simple modelling which further showed that drawdown rate is not so critical for river banks. The findings of this thesis are that draw down at the current rates is not a factor in the failures observed on northern Victorian rivers. The rate of drawdown has not significantly changed since regulation, although the frequency at which specific rates of drawdown occur, has changed. Observational data shows that elevated and sustained nearbank watertable levels cause seepage failures that look like drawdown failures. Permeability is the key factor in the response of the near bank watertable and should be used as a guide to the maximum drawdown rate.
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ItemFacilitating the use of cadastral data through the World Wide Web( 1998-11)Over recent years the cadastral industry has become increasingly reliant on digital data. Many surveyors now submit digital survey plan data to accompany the legally required hardcopy maps and documentation, although it will not be long before total digital lodgement will be possible. In this environment it will be ideal to capitalise on computer networking technology such as the present day Internet and World Wide Web (WWW) to better facilitate the transmission of digital data. This work provides a study of the current climate in the cadastral industry and further identifies how the Internet and its related technologies can be used to facilitate the transmission of digital cadastral data. The focus is to provide a prototype application that facilitates these data transactions in the most effective manner that benefits both user and data provider. This involves a study of the different underlying Internet technologies and how they can be used within the cadastral context. The work presents how the Internet and the WWW can bring benefits in the form of increased data distribution, and, in data integration and update for data maintainers, who need efficient ways of passing digital data to and from different locations.
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ItemA metadata management system for web based SDIs( 1998-12)The process of decision making is best undertaken with the consideration of as much information as possible. One way to maximise the amount of information that is being used in the process is to use metadata engines. Metadata engines can be used to create virtual databases which are a collection of individual datasets located over a network. Virtual databases allow decisions to be made using data from many different data bases at many different locations on a network. They shield the user from this fact. From the users point of view they are only using data from the one location. This thesis investigates some of the concepts behind metadata engines for Internet based Spatial Data Infrastructures. The thesis has a particular emphasis on how metadata engines can be used to create virtual databases that could be of use in the planning and decision making processes. The thesis also investigates some current spatial data technologies such as SDIs, data warehouses, data marts and clearing houses, their interoperability and their relationship to metadata engines. It also explores some of the more recent spatial data applications that have been developed in the context of metadata engines and Spatial Data Infrastructures.
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ItemThe digital lodgement of cadastral survey data in Victoria( 1998-12)An integral part of the Victorian land registration system is the lodgement of cadastral data. Originally data was lodged to support the operation of the land market and the legal rights of the individual owner. The purpose for which it was designed, coupled with the technology that was available at the time, resulted in a paper based system of plans and indexes. Due to many external factors, the current land registration system has essentially remained the same for the past 130 years. However the need for cadastral information means that plan lodgement now serves a wider range of needs, and although changes have been made to the system, it would seem that document-based systems are reaching the limit of cost-effective improvement. A detailed study of the Victorian system of data lodgement has shown there to be several inefficiencies within the system, many of which would benefit by the shift to a digital environment. Research has also shown that the Victorian surveying profession is actually quite prepared to adapt to a digital environment, with many surveyors already preparing or submitting plans digitally. Other jurisdictions that are experiencing similar problems to Victoria have progressed substantially in this area and form ideal examples to learn from. The study of these jurisdictions has shown that although technically the process of lodging data in a digital format is quite straightforward, there are still many technical and legal problems that must be resolved. It is envisaged that in the future, data be lodged in a digital format, which would involve there-engineering of the Victorian land registration system as we know it. This thesis explores the concept of the lodgement of cadastral survey data in a digital format, the issues associated with such a change and the long term benefits it will provide to the surveying, mapping and land development industries.
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ItemDispute Resolution for Customary Lands in Fiji( 1999-02)ivThe rapid increase of land development, the increase in population and theexploitation of natural resources have caused great concern to mostgovernments in the world today. Land and land tenure systems are the keyelements and the key forces which shape the society. However, theconstraints of the land tenure system and the effects of rapid economicdevelopment are visible throughout the world today, especially in lessdeveloped countries. Therefore land problems often break out as disputes. Inthis context, this thesis concentrates on customary land tenure and thecustomary land problems in Fiji.The main purpose of this thesis is to propose an alternative centre for theadministration and management of customary disputes, which will utiliseland information and geographical information to its maximum capabilities.It is anticipated that this model would assist customary landowners, landadministrators and land managers to resolve customary land disputes. TheFiji customary land tenure system is examined, in particular, landownership,land boundaries and land administration. These three topics are discussedindividually and then discussed as a basis of land disputes. It is in these threeareas that a procedure is developed into a system that may help in customaryland dispute resolution.This thesis aims to assist all other countries with customary land tenureproblems, especially those countries of the South Pacific that share the sameprinciples and the same flexibility.
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ItemModelling of flood patterns, using remote sensing, in the Coongie Lakes Wetlands, northeastern South Australia( 1998)The Coongie Lakes is an area of freshwater wetlands located in the Strzelecki desert of north-eastern South Australia. The annual flood pulse from the unregulated Cooper Creek is the principal supply of water to this area of wetlands and of fundamental importance to the ecosystems of the wetlands. Understanding the hydrological factors that affect the flood patterns in arid zone wetlands is vital in the study of the ecology of the wetlands and when assessing the likely ecological effects of any upstream diversion of water from dry land rivers, such as Cooper Creek. The variability of the flood regime of dryland rivers requires that the flooding patterns from a range of flood pulses, with widely differing characteristics, be examined in order to best understand the subtle and complex interactions that are occurring. The use of the AVHRR, data provides the only viable synoptic and temporal coverage that can map the floodwater patterns during current and recent historic, large-scale flood events. The spatial and temporal distribution of floodwaters in the Coongie Lakes was mapped, using NOAA-AVHRR satellite imagery, for the period 1988-1990. Variations between images, not associated with the inherent albedo of the surface, were minimised by applying coefficients to the satellite data that corrected for the different path length of each image. These were measured for the centre of the image and this also minimised in-scene variations due to the wide view angle of the AVHRR. The images were not corrected for changes in atmospheric conditions between the different scenes. The effects of increased atmospheric haze levels and/or highly off-nadir view angles on some images was found to be quite significant and compromised the utility of the affected images in mapping out the distribution and movement of floodwaters. The floodwaters in the wetlands were identified using the ratio of NIR/Red<1('Ratio criterion') and also a NIR Threshold technique (‘Threshold criterion'). The NIR class ranges were selected following the single channel unsupervised classification of a representative subset of images. Three spectral classes were defined (0-16%, 16-23%, 23-30%) and were applied to all images. The floodwaters classes principally corresponded to the percentage of water surface within the pixel. A relationship was established between the spectral classes and depths of the floodwaters by calibrating the measured surface area of lakes against their known volumes. The accuracy of the AVHRR data in measuring the area of inundation was also evaluated by comparing selected images with Landsat MSS images and aerial photographs. The AVIHRR data underestimated the surface area of flooding by 20-30% using the Ratio criterion and 15- 20% range using the Threshold criterion. However, the latter criterion could grossly overestimate the area of flooding in regions of scattered water bodies and dark albedos. Comparing the volumes within the wetlands calculated using the satellite data and those n1easured by Cullyamurra gauge station in each of the three years of flooding (1988-90) gave an average underestimation by the Ratio criterion of 51 % and by the Threshold criterion of 35%. These underestimations also were caused by water losses other than by evaporation and so overstate the error range for the volume calculations. The range of flood pulse sizes observed during the study period were divided into five classes based on ranges for the peak daily flow amplitude and total volume of the flood pulse. The extent of flooding for each of these classes was defined. The monitoring of , ' the movement of a range of flood pulses through the wetlands also allowed the identification of the main controls on the patterns of inundation. The pattern of flooding within the wetlands was most influenced by the amplitude (peak and at flood head), shape and total volume of the flood pulse. Other critical factors included the pre-existing water volume in the wetlands, the flow rate, catchment source of the flooding and the floodplain volume capacity upstream of important geomorphological, flow-regulating features.
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ItemDewatering of sewage sludge( 1996)Sewage sludges are biological sludges which exhibit wide variations in their physical, chemical and biological properties. The large and increasing amount of sludge produced has caused significant disposal problems. Apart from the steadily growing sludge volumes the cost per tonne of dumped waste also shows a continuous upward trend. Therefore, this research aimed at investigating the application of one of the most common dewatering technique which was vacuum filtration to dewater sewage sludge. The effects of impermeable membrane, vacuum level, conditioning, fibre, solids loading and cost of various dewatering techniques were investigated. The performance of the sludge was determined by capillary suction time (CST), torque (viscosity) and filtration rate. The CST and torque were determined using the CST apparatus and viscometer, respectively. The filtration was carried out using laboratory scale vacuum filters. The solids content of alum, South-Eastern and Mornington sludges were found to be 1.4%, 2.5% and 2%, respectively. The alum had the lowest fibre content (approximately none) while the Mornington had the highest fibre content (9.9%). Alum sludge had a much lower CST when compared to sewage sludges. Cationic polyelectrolytes reduced the CST of sewage sludges dramatically. The performance of most Zetag polyelectrolytes was good and consistent while CP408HMW had the poorest performance. For lllost polyelectrolytes, the pattern showed a rapid decrease in the first instance leading to a very small decrease (almost constant), followed by another rapid decrease leading to a constant again. In all cases, yield torque was found to increase with polyelectrolyte dose. Both the CST and yield torque decreased with stirring time to a minimum and then increased again with further stirring. The change in torque was found to change dramatically with the change in sludge volume. When the impermeable membrane was introduced, it was found that it was not feasible to carry out the experiment in the absence of polyelectrolyte. When polyelectrolyte was used, the filtration rates and final percentage solids (20% to 25%) were found to improve dramatically. The impermeable membrane itself did not have a profound effect on the filtration performance. Filtration rate was found to increase with increasing vacuum level. When different solids loadings were tested, it was found that the performance of the filtration improved with increasing solids loadings. Both the CST and filtration results showed that conditioned sludge performed better after aging. However, unconditioned sludge gave an entirely opposite result in which the sludge had poorer filterability with increasing age. Fibres were found not to have a profound effect on filtration rates. However, the fibres were found to be able to reduce or even eliminate cracking of the cake. From the economic analysis performed, it can be concluded that filter press had the highest total cost followed by centrifuge, sand drying beds and vacuum assisted drying beds. The cheapest alternative was the vacuum assisted drying bed. Vacuum assisted drying bed was the most feasible option if the plant life was short (<20 years).
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ItemFlexural ductility of high strength concrete columns( 1995)A method for the design of reinforced high strength concrete columns considering the flexural ductile behaviour is presented in this thesis. High strength concrete, as used in this study, is defined as concrete with compressive strengths exceeding 50MPa. The study covers the following areas: A concrete stress-strain model previously used for normal strength concrete column analyses is presented along with a modification to include the characteristic behaviour of high strength concrete. The thesis also gives a literature review of the available information on the performance of high strength concrete columns. An experimental investigation of the influence of concrete strength, stirrup spacing, axial load level, and the percentage of longitudinal steel on the stress-strain and movement-curvature behaviour of confined concrete is presented. The test units included eight rectangular columns of compressive strengths ranging from 30 to 65MPa. The available strength and ductile behaviour of the columns is discussed and compared with the performance of columns tested previously at the University of Melbourne and Monash University, as well as with various analytical models, including the modified concrete stress-strain model mentioned above. A method for the determination of stirrup spacing resulting in equivalent ductile performance to that specified by the current Australian Concrete Code (AS3600) is presented. A set of criteria for the ultimate limit state including longitudinal steel buckling and lateral steel fracture was used to establish a design method for the available strength and ductility of high strength concrete columns. The effect of concrete cover on ductile behaviour is also discussed. Various spreadsheets were developed to determine such parameters as concrete strain at lateral steel fracture and strain at longitudinal steel buckling. A spreadsheet which determines the stirrup spacing of a column as specified by various codes and research reports was also developed. Two fortran computer programs which determine the axial force - moment interaction diagram and the moment-curvature curve of a reinforced concrete section were modified to include new stress-strain relationships suitable for high strength concrete and ductility measurements.