School of Engineering Scholarly Works
Images from series: School of Engineering Scholarly Works

Permeability characteristics of fibre-reinforced Perth sandy soil

Fibres are mixed with soils to enhance their strength and hydraulic characteristics. Fibre-mixed soils are often known as the fibre-reinforced soils. In the past, both systematically and randomly reinforced soils have been used widely in civil and geotechnical structures. Randomly reinforced-soils using fibres exhibit advantages over systematically reinforced-soils because systematic reinforcements may result in weak planes within the soil mass. Randomly distributed reinforcements are also easier to apply and maintain for some applications.

Previous researchers have studied the strength, compaction and compressibility behaviour of fibre-reinforced soil. Study on characteristics of fibre-reinforced soils when saturated, however, is limited to piping resistance improvement. One of the main reasons for collapse of some of the hydraulic structures is soil piping that takes place on the downstream side as a result of upward seepage. Fibre-reinforced soils can be a solution in sustainable watershed management as they can be used in irrigation and drainage projects, such as river levees, contour bunds, temporary canal diversion works, temporary check dams, soil structures, stream restoration, etc., for seepage and permeability control.

This study focuses on permeability characteristics of fibre-reinforced soil. Permeability characteristics can vary depending on soil, fibre and methods used. Materials used in this study are Perth sandy soil, and locally available jute and waste tyre fibres. These materials were chosen because they are abundantly available in Perth area and surroundings. As for the waste tyre fibre, it was also chosen as a green approach to use waste materials in structures and solve their disposal problems. Fibre content varied from 0 to 10% with 1% intervals for tyre fibres and from 0 to 1.5% with 0.25% intervals for jute fibres. Fibre length varied from 5 to 25 mm with 5 mm intervals for jute fibres. Fibre length was constant in all experiments for tyre fibres as they come in a mixture of different lengths and studying the effect of length of permeability characteristics was not possible. Experimental tests were conducted on fibre-reinforced specimens in a constant-head permeameter. Experimental results suggest that the coefficient of permeability increases with an increase in fibre content for both fibre types (up to 100% for jute fibres and up to about 40% for tyre fibres). Also, it is observed that the coefficient of permeability increases with an increase in fibre length for jute fibres, as a general trend. As expected, water content increases and dry and saturated unit weights decrease with inclusion of higher fibre contents and longer fibres as a general trend.

Fibre-reinforced soil specimens and the water discharge were modelled numerically using the commercial software SEEP/W in order to study the effects of fibre inclusion on permeability characteristics. The findings from the developed numerical model agree well with the experimental observations.

https://ro.ecu.edu.au/theses/2175

An insight into waste management in Australia with a focus on land fill technology and liner leak detection

It is critical for landfilling facilities to follow proper waste handling and management practices. These include the use of suitable lining systems for waste containment, and the implementation of efficient leakage monitoring and detection systems. In this paper, an attempt has been made to present the current state of landfilling in Australia with a focus on the lining practices and leak detection methods. An extensive study was conducted involving different private and public waste handling and management facilities in all the states and territories of Australia. Based on the survey and the information available in the public domain, it was observed that different landfill sites practiced non-uniform set of directives for waste classification, siting, design, operation and rehabilitation. Majority of the facilities were found to be publicly owned. The use of groundwater monitoring wells for leakage detection was more prevalent than other leak detection methods. Further, a new method of leak detection by the simulation of landfill lining system, which is being developed and investigated in our research, is also presented. This study is particularly useful in generating awareness about the state of landfilling and will help various environmental protection agencies in making informed decisions for the development of rules and regulations to govern landfills. The new leak detection method as developed in our research can find applications in the development of monitoring systems for landfill liners, subbase contamination detection, and development of sensors.

https://ro.ecu.edu.au/ecuworkspost2013/6013

The potential of integrating vehicular emissions policy into Ghana’s transport policy for sustainable urban mobility

Auto vehicle emissions are a major challenge for ambient air pollution control in most developing countries including Ghana. Major auto emissions, particulate matter, are critical road transport emissions that threaten human health and the environment but are often excluded from policy discussions. In Ghana, vehicle acquisition schemes are not environmentally friendly and current national policies have alienated the monitoring of airborne emissions from the transport sector. This calls for the design and implementation of green transport and fuel economy options. We discuss the critical role of motor vehicle particulates in Ghana and propose policy solutions for sustainable urban mobility. We have shown that environmental remediation, social equity and sustainability can only be achieved when transport emissions are properly integrated in a coordinated transport policy. Ghana has a National Transport Policy that recognizes the challenges of environmental pollution due to vehicular emissions and uneconomic fuel consumption. There are green fuel policy proposals and a vehicle testing and licensing regime that is largely driven by mechanical and electrical functionality. Auto-vehicle emissions performance standards have not been developed and technical capacity for emissions testing is lacking. Ambient air monitoring is limited to particulate matter which is not nationally representative as it is confined to Greater Accra Region at only 15 sites. 77% of road users believe 20% of all cars in urban centres visibly exude fumes. Noise pollution and vehicular emissions were reported at 78% and 75% of 160 respondents respectively. Vehicle owners, drivers and driver unions are apprehensive of electric cars but would welcome a reliable, convenient and efficient mass transport system. Abatement strategies to reduce vehicular emissions particulates will require integrated solutions and inter-agency collaboration among regulatory institutions. The Environmental Protection Agency and Driver and Vehicle Licensing Authority should be empowered to develop emissions performance standards and conduct real time monitoring of particulates with the assistance of the Motor Traffic and Transport Department of the Ghana Police Service. It is further recommended that volatile organic compounds, particularly benzene series contaminants, should be monitored by the Agency. Further research on vehicular emissions of volatile organic compounds and their health effects on road users should be carried out to understand the full impact of exposure of on-road emissions.

https://ro.ecu.edu.au/ecuworkspost2013/8164

Copper removal from acid mine drainage-polluted water using glutaraldehyde-polyethyleneimine modified diatomaceous earth particles

Mine waters and tailings generated from mining and mineral processing activities often have detrimental impact on the local environment. One example is acid mine drainage, in which sulphides in the mining waste react with water and oxygen to produce an acidic environment that subsequently dissolves host rock minerals from the waste containing toxic metals and trace elements. Copper is one such metal of significance, as it is mined at large volumes in sulphide containing ores. It has strong biocidal activity that greatly affects ecosystems. We have previously reported that glutaraldehyde (GA)-crosslinked polyethyleneimine (PEI) has strong affinity and selectivity for copper and that diatomaceous earth (DE) particles can be modified with the material to form a copper-extraction resin. In this study, the copper uptake of GA-PEI-DE particles was investigated from synthetic and real acid mine drainage samples under different pHs and their copper removal performance was compared with that of selected commercial resins. The results revealed that copper could effectively and preferentially bind to the material at pH 4, and that the copper could be completely eluted by lowering of the pH. In addition, effective copper uptake and elution was demonstrated using real legacy acid mine drainage water from Mount Lyell in Tasmania.

https://ro.ecu.edu.au/ecuworkspost2013/4222

Using agricultural wastes to treat lead-contaminated water in Western Australia

Aqueous solutions are becoming increasingly contaminated in all parts of the world (2015). Heavy metals are toxic contaminants that are mainly distributed in urban stormwater run-off and industrial wastewaters as a result of some mining operations, electronic assembly planting, battery manufacturing, and etching operations (Kadirvelu et al. 2001). Pb (II) is a heavy metal that causes significant damage in the human body. Drinking lead-contaminated water even at low concentrations may cause lifethreatening conditions such as cancer, kidney damage, brain damage, and liver problems (El-Said 2010). Therefore, it is necessary to remove lead from aqueous solutions.

Several conventional physical, chemical, and biological systems have been used to eliminate Pb (II) ions from contaminated aqueous solutions, including membrane filtration (Song et al. 2011), electrolysis (Deng et al. 2010), chemical precipitation (Cort 2005), magnetic base methods (Ma et al. 2017), water filtration (Gohari et al. 2013, Magni et al. 2015), and adsorption techniques (Pehlivan et al. 2009). However, the cost of some of the cited techniques is prohibitively high, while others cannot remove low Pb (II) ion concentrations efficiently (Babel and Kurniawan 2003, Volesky and Holan 1995). Although adsorption is a reasonable process for removing dissolved lead from contaminated water, the cost of using conventional media (e.g. activated carbon and resin) make it cost inhibitive for the treatment of large quantities of wastewater (Cutillas-Barreiro et al. 2016, Demirbas 2008). It also takes a long time in some cases to achieve adsorption equilibrium (Czinkota et al. 2002).

In recent decades, interest in the use of cost-effective adsorbents to reduce the expense of water treatment processes has intensified. Attention has been focused on natural agricultural waste materials such as seeds (Gilbert et al. 2011), fruit peel (Mallampati et al. 2015), nut shells (Taşar et al. 2014) , crop residues (El-Said 2010), and fruit shells (Zein et al. 2010) as low-cost and environmentally friendly adsorbents which are highly efficient and generally available in large quantities (Ibrahim et al. 2010).

Against this backdrop, many agricultural residues are being produced every day, and they need to be managed. Using agricultural wastes to treat contaminated water is a low-cost and effective approach that deal with waste management and water treatment at the same time. This project describes an economically viable and practical way to utilize crop residues as adsorbents to remove toxic Pb (II) ions from lead-contaminated water. These agricultural waste adsorbents have a number of advantages; they are cheap and biodegradable, they have a porous surface, and are able to eliminate Pb (II) ions from contaminated water quickly and effectively.

Therefore, in this research two Western Australian crop residues were used as adsorbents to eliminate lead ions from aqueous solutions. The study was carried out in four phases: the first phase involved the selection and preparation of different local Western Australian agricultural wastes. Lupin straw and canola stalk were collected from local farms and studied for their efficiency as two low-cost natural adsorbents that can remove dissolved Pb2+ ions from synthetic wastewater.

In the second phase, experiments were carried out to understand the equilibria of Pb (II) adsorption onto adsorbents. The effect of various environmental conditions such as contact time, pH, initial adsorbent dosage and adsorbate concentration were investigated.

The presence of different functional groups, chemical compositions, and the surface characteristics of the adsorbents were analysed in the third phase using energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) devices. In the final phase, the obtained experimental data were validated using different isotherm models developed by Langmuir, Freundlich, Harkins-Jura, Redlich- Peterson and Halsey to describe the adsorption process based on the homogeneity of the surfaces of the adsorbents. Pseudo-first-order, pseudo-second-order, intra-particle diffusion, Elovich, and fractional power kinetic models were utilized to investigate the dynamic mechanism of lead adsorption onto adsorbents over time.

https://ro.ecu.edu.au/theses/2086

Optimum sizing of a stand-alone hybrid energy system for rural electrification in Bangladesh

This study investigates the potential application of hybridized energy system (i.e., PV/Wind/Diesel) with battery storage in the northern region of Bangladesh. A techno-economic feasibility of different system configurations is evaluated and an optimized system is selected using HOMER (Hybrid Optimization Model for Electric Renewable) software. The hybrid system is optimized to meet a remote stand-alone village community's load demand of 242.56 kWh/day with a 51.52 kW peak load demand. The result of this study indicates that the optimized hybrid system consists of 73 kW PV arrays, a 57 kW Diesel generator, a 387 kWh nominal capacity battery bank, and 28 kW inverters have the minimum Cost of Energy (COE) of 0.37$/kWh and the Net Present Cost (NPC) of $357,284. The outcome also indicates that the optimized system reduces CO2 emission by around 62% in comparison with the kerosene used in a current situation and 67% with the grid connected system. Furthermore, the Life Cycle Emissions-LCE (kg CO2-eq/yr) production is considerably lower in PV/Batt/ICE system than the other system configurations. However, this system has a lower Duty Factor (DF) compared to Wind/Batt/Diesel and Batt/Diesel based system. Although this system is not comparable with the grid tariff, the proposed method is economically feasible than solar micro utility system, Wind/Batt/Diesel system, and Diesel generator only system. Additionally, the article discusses the social and economic benefits of implementing the hybridized system along with their barriers and challenges.

A hybrid energy management and battery size optimization for standalone microgrids: A case study for Flinders Island, Australia

Microgrids are increasingly being used as a platform to integrate distributed generation such as renewable energy sources and (RESs) conventional sources in both grid-connected and isolated power systems. Due to the inherent intermittent nature of RESs, energy storage systems (ESSs) that can absorb fluctuations have become inevitable. Nevertheless, large capacities of ESSs increase the initial cost while small capacities lead to instabilities and increase in the cost of conventional fuels. Therefore, finding the optimal size of the ESS for a given application is essential for the reliable, efficient and economical operation of a microgrid. Once the battery size is decided, maintaining its energy at appropriate levels is essential to ensure stable and safe operation of the microgrid. This paper presents a novel expert fuzzy system - grey wolf optimization (FL-GWO) based intelligent meta-heuristic method for battery sizing and energy management. The proposed energy management operation is carried out by a Grey Wolf Optimiser (GWO) that is helped to set the membership functions and rules of the fuzzy logic expert system. The unit commitment (UC) issue, which is essential for the proper operation of the isolated microgrid, has been additionally considered in this paper. To verify the performance of the proposed method, results are compared with the rules-based method and traditional GWO algorithm. It has been proven from the results that the FL-GWO has a significant convergence property and capability to minimize the Levelized Cost Of Electricity (LCOE) by 14.13% and 24.15% compared with conventional GWO algorithm and rules-based method, respectively. The weather conditions for different climates is used to verify the performance of the intelligent energy management method under different operating scenarios. The results show that the intelligent online multi-objective energy management strategy is capable of managing a smooth power flow with the same optimal configuration in the isolated microgrid, minimising the fossil fuel utilisation and reducing the CO2 emission level.

A techno-economic feasibility of a stand-alone hybrid power generation for remote area application in Bangladesh

A techno-economic feasibility of a stand-alone hybrid power generation for a remote community in Bangladesh is carried out in this study. The proposed system integrates a combination of biogas generator, PV modules, diesel generators, wind turbines, and lead acid battery to meet the electric load requirements using Hybrid Optimization Model for Electric Renewables (HOMER) software tool. The designated system would satisfy the energy requirements of 248 kWh/day primary load with 44.41 kW peak load. The optimized hybrid system consists of a biogas generator (9 kW), PV modules (10 kW), 2 diesel generators (10 kW each), 72 batteries (390Ah each), and 15 kW inverters. This configuration gives the COE of $0.28/kWh and total Net Present Cost (NPC) of $612280 with a renewable fraction of 60%. Additionally, the system has potential benefit to reduce CO2 emission by nearly 59.6% per year as compared to a diesel-based system and by 40.5% compared to the grid electricity. Furthermore, the results also indicate that it is fairly impossible to reach grid electricity price parity even with full government support for the project capital cost. However, the proposed system is found as an economical option than supplying electricity to the remote community with solar home systems (SHSs).

Metal-free hybrids of graphitic carbon nitride and nanodiamonds for photoelectrochemical and photocatalytic applications

Graphitic carbon nitride (g-C3N4) has been considered as a metal-free, cost-effective, eco-friendly and efficient catalyst for various photoelectrochemical applications. However, compared to conventional metal-based photocatalysts, its photocatalytic activity is still low because of the low mobility of carriers restricted by the polymer nature. Herein, a series of hybrids of g-C3N4 (GCN) and nanodiamonds (NDs) were synthesized using a solvothermal method. The photoelectrochemical performance and photocatalytic efficiency of the GCN/NDs were investigated by means of the generation of photocurrent and photodegradation of methylene blue (MB) solutions under UV–visible light irradiations. In this study, the sample of GCN/ND-33% derived from 0.1 g GCN and 0.05 g NDs displayed the highest photocatalytic activity and the strongest photocurrent density. The mechanism of enhanced photoelectrochemical and photocatalytic performances was also discussed.

Calibration of Valiantzas' reference evapotranspiration equations for the Pilbara region, Western Australia

Reference evapotranspiration (ET0) is a critical component of water resources management and planning. Different methods have been developed to estimate ET0 with various required data. In this study, Hargreaves, Turc, Oudin, Copais, Abtew methods and three forms of Valiantzas’ formulas, developed in recent years, were used to estimate ET0 for the Pilbara region of Western Australia. The estimated ET0 values from these methods were compared with those from the FAO-56 Penman-Monteith (PM) method. The results showed that the Copais methods and two of Valiantzas’ equations, in their original forms, are suitable for estimating ET0 for the study area. A modification of Honey-Bee Mating Optimization (MHBMO) algorithm was further implemented, and three Valiantzas’ equations for a region located in the southern hemisphere were calibrated.

Digital change detection and separation of anthropogenic and natural impacts on ecohydrological conditions in the Pilbara region, WA

A deficiency in crucial digital data, such as vegetation cover, in remote regions is a challenging issue for sustainable water management and planning, especially for areas undergoing rapid development, such as mining in the Pilbara, Western Australia. This is particularly relevant to Inflow and Groundwater Dependent Vegetation (IGDVs) (riparian vegetation and groundwater dependent vegetation) which provide important ecological services and, as such, require regional protection. However, such invaluable assets experience changes over time due to either human activities such as land development or natural phenomena such as climate change or fire events.

The main objectives of this research was to 1) advance an approach to delineate inflow dependent ecosystems at a local scale; 2) adopt it to map the assets at regional scale using remotely sensed data (Landsat 5 TM imagery due to its appropriate temporal and spatial resolution for historical studies, 1986-2011), ground-truth data and available information such as reports, digital layer and climate data; 3) develop a method for identification and quantitative assessment of IGDVs changes and attribution of the changes to particular impacts or stressors, and 4) apply the developed change detection method to investigate and evaluate impacts of an adopted water resource management options on inflow dependent assets in the Pilbara.

Outcomes of the research exposed that the proposed delineation method allowed production of accurate inflow dependent ecosystems maps for the Pilbara bioregion. The change detection method was also effective in detecting various spatial and temporal scales of changes and separating anthropogenic and natural impacts. It was further discovered that climate has had significant impacts on the assets of the area.

The finding and information produced from this research is capable to aid government, industry and communities to consider the environmental, social, cultural and economic aspects of the sustainable use, development and management of land and water resources in arid and semiarid Pilbara, WA and areas with similar ecohydrological conditions. Four papers were prepared from the research, two are published and two are under review.

https://ro.ecu.edu.au/theses/1951

Delineation of riparian vegetation from landsat multi-temporal imagery using PCA

A deficiency in crucial digital data, such as vegetation cover, in remote regions is a challenging issue for water management and planning, especially for areas undergoing rapid development, such as mining in the Pilbara, Western Australia. This is particularly relevant to riparian vegetation, which provides important ecological services and, as such, requires regional protection. The objective of this research was to develop an approach to riparian vegetation mapping at a regional scale using remotely sensed data. The proposed method was based on principal component analysis applied to multi-temporal Normalized Difference Vegetation Index datasets derived from Landsat TM 5 imagery. To delimit the spatial extent of riparian vegetation, a thresholding method was required and various thresholding algorithms were tested. The accuracy of results was estimated for various Normalized Difference Vegetation Index multi-temporal datasets using available ground-truth data. The combination of a 14-dry-date dataset and Kittler's thresholding method provided the most accurate delineation of riparian vegetation

Variation trend of dry-wet climatic factors and correlation with wetlands in western Jilin Province, China

The variation of climate elements and its relationship with wetland landscape in western Jilin Province (WJL) were studied to support decision-making for drought prevention and ecology protection. Mann-Kendall test and linear regression algorithm methods were used to analyze the characteristics of climate change, using a large amount of data of temperature, precipitation, evapotranspiration and dry-wet index, collected from nine monitoring stations during 1960-2014. The results showed that annual temperature and dry-wet index in WJL displayed a ascendant tendency, with the average rate of 0.34℃/10a and 0.14/10a, respectively. The annual precipitation and potential evapotranspiration showed a declining trend; decreasing by about -7.92mm/10a and -3.4mm/10a, respectively. Homogeneous trend was found for temperature and evapotranspiration in the autumn; an increasing trend observed. A sharp declining trend was found in the summer season for precipitation, which was the biggest contributor to the overall decrease of annual precipitation. The spatial distribution of annual and seasonal climate factors indicated that the WJL area is becoming drier, especially in the summer and autumn seasons. The wetland landscape indexes in most regions are significantly correclated with summer precipitation. The significance level for I, II and IV regions located in the west of WJL reached 99%. It is important to plan responding measures of water resource management, to counter the decrease of summer precipitation in western WJL, and reduce the impact of drought and wetlands degradation, which is possibly caused by the global climate change.

Vortex-induced motion of a free-standing riser below the critical mass ratio

The presented work studied the vortex-induced motion (VIM) response of a free-standing riser (FSR) with varied riser length and buoyancy can (BC) mass with an ultimate aim to find a combination that would reduce the motion of the system. Specifically, four model configurations were experimentally tested in a flume tank over a range of flow velocities, with the BC motion recorded by a submersible camera positioned directly above the model; consequently, inline (IL) and crossflow (CF) amplitudes were estimated with a motion tracking software. In the pre-resonant flow regime, non-dimensionally, minimal differences were observed between the CF amplitudes, and the IL motion was reduced with a longer riser. Given the extreme length of full-scale FSRs and inherent low natural frequency, it is impractical to increase the riser tension to a point where VIM would not occur under normal environmental conditions. Alternatively, increasing the mass ratio of the BC so that it is above the critical mass ratio of 0.54 (the ratio of the mass of the body to the mass of the fluid) would limit the resonant flow velocities to a finite range, but a larger BC may not be an economically viable solution, and because of the increased diameter, it would experience a larger CF amplitude during resonance. Further study into the prevention of VIM of an FSR by varying the riser length and BC mass is unlikely to be beneficial.

Large-scale regional delineation of riparian vegetation in the arid and semi-arid Pilbara region, WA

Multiscene Landsat 5 TM imagery, Principal Component Analysis, and the Normalized Difference Vegetation Index were used to produce the first region-scale map of riparian vegetation for the Pilbara (230,000 km2), Western Australia. Riparian vegetation is an environmentally important habitat in the arid and desert climate of the Pilbara. These habitats are supported by infrequent flow events and in some locations by groundwater discharge. Our analysis suggests that riparian vegetation covers less than 4% of the Pilbara region, whereas almost 10.5% of this area is composed of groundwater dependent vegetation (GDV). GDV is often associated with open water (river pools), providing refugia for a variety of species. GDV has an extremely high ecological value and are often important Indigenous sites. This paper demonstrates how Landsat data calibrated to Top of Atmosphere reflectance can be used to delineate riparian vegetation across 16 Landsat scenes and two Universal Transverse Mercator spatial zones. The proposed method is able to delineate riparian vegetation and GDV, without the need for Bidirectional Reflectance Distribution Function correction. Results were validated using ground truth data from local and regional scale vegetation surveys.

Resistivity profiles of Perth soil in Australia in leak-detection test

The use of a suitable leak-detection system for the prevention and mitigation of pollution due to lining system failures is integral to the proper management of landfill facilities. This paper briefly summarises various methods of leak detection that are currently being practised. The details of a newly developed leak-detection technique are also presented. The tests were conducted to evaluate the performance of the new technique by use of controlled leakage. The resulting resistivity profiles for Perth soil in Australia were obtained at 10 min. This method is found to be effective in detecting and locating liner leakage issues within 30 min from the instant when the defect develops. The electrical resistivity decreases with an increase in the leakage duration. The resistivity was found to increase with an increase in the distance/depth from the leak point. Installation of this innovative detection system below liners can enable the various waste containment facilities, such as landfills and leachate ponds, to monitor the lining systems and in case of failures, to take timely action for hazard mitigation. Results presented in this study can be useful for further development of sensors for leakage detection in lining systems

Calculation of wetlands ecological water requirement in China’s Western Jilin province based on regionalization and gradation techniques

In this study a method for measuring the regional hydrological connectivity and water supply requirement of wetlands in Western Jilin Province (WJL) is defined and verified. The ecological water requirements of 216 wetlands, under various guarantee frequencies, were calculated and analyzed. In addition, twelve indicators were used to establish an evaluation index system, to characterize their ecological water requirements. The results showed that 12 hydrologically connected regions were delineated in WJL, and the 216 wetlands can be classified to six grades by AHP (Analytic Hierarchy Process) method. The annual minimum, suitable, and maximum ecological water requirements of these wetlands were found to be 7.72×108 m3, 13.76×108 m3, 26.15×108 m3 respectively, with 50% guarantee frequency. The primary water supply to the lakes and marshes was found to be from regional sources that provided a scientific basis for the allocation of water resources from the interconnected river-lake system network (IRLSN) in WJL. © 2016, ALÖKI Kft., Budapest, Hungary.

Compositions, logratios and geostatistics: An application to iron ore

Common implementations of geostatistical methods, kriging and simulation, ignore the fact that geochemical data are usually reported in weight percent, sum to a constant, and are thus compositional in nature. The constant sum implies that rescaling has occurred and this can be shown to produce spurious correlations. Compositional geostatistics is an approach developed to ensure that the constant sum constraint is respected in estimation while removing dependencies on the spurious correlations. This study tests the applicability of this method against the commonly implemented ordinary cokriging method. The sample data are production blast cuttings analyses drawn from a producing iron ore mine in Western Australia. Previous studies using the high spatial density blast hole data and compositional geostatistical approach returned encouraging results, results other practitioners suggested were due to the high spatial density. This assertion is tested through sub-sampling of the initial data to create four subsets of successively lower spatial densities representing densities, spacings, and orientations typical of the different stages of mine development. The same compositional geostatistical approach was then applied to the subsets using jack-knifing to produce estimates at the removed data locations. Although other compositional geostatistical solutions are available, the additive logratio (alr) approach used in this study is the simplest to implement using commercially available software. The advantages of the logratio methodology are the removal of the constant sum constraint, allowing the resulting quantities to range freely within the real space and, importantly, the use of many proven statistical and geostatistical methods. The back transformation of linear combinations of these quantities and associated estimation variances to the constrained sample space is known to be biased; this study used numerical integration by Gauss-Hermite quadrature to overcome this drawback. The Aitchison and Euclidean distances were used to quantify both the univariate and compositional errors between the estimates and original sample values from each estimation method. The errors of each method are analysed using common descriptive and graphical criteria including the standardised residual sum of squares and an assessment of the accuracy and precision. The highest spatial density dataset is equally well reproduced by either method. The compositional method is generally more accurate and precise than the conventional method. In general the compositional error analyses favour the compositional techniques, producing more geologically plausible results, and which sum to the required value. The results support the application of the logratio compositional methodology to low spatial density data over the commonly implemented ordinary cokriging.

Behaviour of waste tyre fibre-reinforced cement-stabilised Perth sand

There are several improvement methods available for modifying soils. Cement stabilisation has been one of the popular improvement methods for cohesionless soils. Over the past three decades, many studies have been done to investigate the effects of adding synthetic and natural fibres to soil as the reinforcing material alone or with cement. Utilisation of the fibres from waste materials such as used tyres and carpets, which are available in large quantities worldwide, can be beneficial.

Though significant research has been conducted on studying the behaviour of cement-stabilised soil, the effectiveness of using waste tyre fibres (TF) with cement has received very limited attention. Therefore, the present work focuses on investigating the characteristics of local Perth sandy soil after inclusion of waste TF and cement. These wastes can be utilised in ground improvement in large quantities and could provide a cost-effective and environmentally friendly strategy that avoids tyre disposal problems.

A series of laboratory tests including compaction, unconfined compression and triaxial tests were conducted to investigate the effects of adding TF and cement on the engineering behaviour of Perth sandy soil. Two types of TF namely tyre fibres A (TFA) whose particles were smaller in length and diameter than the other type called tyre fibres B (TFB) were used. The contents were varied from 0 to 3% of dried sand by weight both for cement and TF. The cemented specimens were cured in a humid room for 7 days. For the triaxial tests, the confining stresses were 50, 100 and 200 kPa.

The compaction test results indicate that the maximum dry unit weight is generally increased by adding cement and decreased by TF inclusion, while adding cement and TF results in a lower optimum water content.

The results of unconfined compression tests show that the cement addition increases the unconfined compressive strength (UCS ) of the sand and sand-TF mixtures. Furthermore, the inclusion of TF in the sand increases its UCS , whereas UCS of the sand-cement mixtures decreases with an increase in tyre fibre content, except for a slight increase at low cement contents. The highest improvement occurred when 1% TFB was added to sand + 1% cement with an increase of UCS from about 314 kPa to 338 kPa. Moreover, while adding the cement increases the modulus of elasticity ( E ), the inclusion of TFs reduces E , and the greatest reduction was observed when 3% TFB was added to sand with 3% cement ( E decreased from about 4186 kPa to 1537 kPa).

The triaxial results indicate that adding TF to sand leads to a slightly higher effective angle of friction with a reduced effective cohesion. However, overall, a marginal difference is observed in the stress-strain characteristics of unreinforced and TF-reinforced soil. Generally, it was observed that the use of TFB was slightly more efficient compared to TFA in both cemented and uncemented sand mixtures due to higher aspect ratios of TBF and accordingly, greater reinforcement effect. Overall, TF-reinforced sand, with or without cement, is a lighter material with improved strength, which can be used in some civil applications such as slope stabilisation, backfills or embankments.

Water resource options for sustainable development in the Pilbara region of Western Australia

Water resources management in the Pilbara region of Western Australia is vital to industry, economy and the environment. This dissertation has aimed to develop a comprehensive hydrological and hydrogeological assessment of water resources in the Yandi mine area located in the Weeli Wolli Creek catchment in the Pilbara. Water resources in this area have become increasingly vulnerable due to growing demand. Climate conditions, geology and hydrogeology, streamflow and the groundwater system of the study area were assessed. Lumped, data-driven and numerical models were employed to develop an understanding of the available surface water and groundwater resources.

Three equations were derived showing the rainfall-runoff relationship within Weeli Wolli Creek catchment and subsequent modelling was undertaken for more hydrology system evaluation. Artificial Neural Networks (ANNs) and IHACRES models were used to simulate the Marillana Creek streamflow discharge, upstream of Yandi. The results suggested that ANN models perform better for a complex catchment hydrological system, compared to IHACRES model.

A VISUAL MODFLOW model was used to investigate the groundwater system and its trend in the Yandi area. The model helped to understand the groundwater responses to future development with various pumping strategies and climate conditions. The scenario analysis assisted identification of zones vulnerable to a significant decline in groundwater level in response to dewatering. The analysis indicated that the maximum water level drawdown of 25m occurred in the aquifer from maximum annual pumping of 23GL. With respect to groundwater yield in particular, abstraction has a more direct impact on the groundwater system compared to climate change.

The recharge into the groundwater was estimated from the fluctuations of groundwater level, groundwater modelling and water balance method. The estimated recharge from these methods was comparable and consistent within 3 to 5% of rainfall. This suggests that direct rainfall infiltration is less, compared to localised infiltration. Two new equations, applicable to Australian conditions, were developed to estimate potential evapotranspiration (ET0). These equations form a part of the water balance equation for groundwater recharge estimation. An artificial intelligent model, based on the Honey-Bee Mating Optimization algorithm (HBMO), was introduced to calibrate the new ET0 equations. The newly developed equations had better performances than available popular equations.

The results of this study showed that the water resources in Yandi are considerably affected by progressing activities and their associated water requirements. A combination of multiple water assessments and modellings suggested that it is feasible to predict future access to surface water as a function of its influencing factors such as climate condition and mining activities. Scenario analysis in groundwater assessment suggested possible alternative future dewatering strategies in the Yandi mine area. The possible groundwater level recovery time is estimated to be one hundred years, which indicates this resource may not be a reliable option in future. Hydrological water balance analysis also indicated that the available surface water volume would decrease to half upon cease of discharge due to closure of mines in the study area, which is controversial condition for future water management.

This research can lead to the implementation of a sustainable water resources plan, and development of appropriate strategies.

Assessment of Artificial Neural Networks and IHACRES models for simulating streamflow in Marillana catchment in the Pilbara, Western Australia

A wide range of techniques are available to model hydrological processes. Choosing a model is not a straightforward task considering geographical and climate conditions. Although this is an exercise with some level of uncertainty it does help to understand hydrological processes which are used for the management and development of water resources. In Western Australia with its arid or semi-arid climate, water resource management is a key issue for future sustainable development. In this study, IHACRES, a physical-based hydrology model, and Artificial Neural Networks were used to simulate the daily water discharge from Marillana Creek catchment in the Pilbara in Western Australia. Although, these models did not produce satisfactory results, the comparison of the results show that the ANN model can be a feasible alternative for complex hydrology systems with poor recorded data. Also, data from two neighbouring gauges were successfully used to improve the result of Artificial Neural Networks over the IHACRES model.

Water quantity and quality assessment on a tertiary treatment wetland in a tropical climate

This study aimed to assess the quantity and quality of water in a surface flow constructed wetland in Australia's far north Queensland. Owing to tropical climate in the region, the wetland provided dual functions: retention of a treated wastewater for zero discharge during the dry season and tertiary treatment prior to discharge during the wet season. Rainfall data, permeability of wetland soil, evaporation, inflow and outflow were analysed in a water balance analysis; the results showed that based on a 72-year-average rainfall pattern, daily wastewater inflow of 85 m3/d is the maximum this wetland can cope with without breaching its discharge certificate. In water quality analysis, the K-C∗model was used to predict changes of biochemical oxygen demand (BOD, suspended solids (SS), total nitrogen (TN), total phosphorus (TP) and faecal coliforms (FC) in the wetland. Model predictions were compared with field sampling results. It was found that the wetland was effective in removing FC (>99.9%), TN (70.7%) and TP (68.2%), for which the predictions by the K-C∗model were consistent with field testing results. However, signi ficant disparities between the predictions and testing results were found for BOD and SS. A revised K-C∗equation was proposed to account for the internal generation of organics in constructed wetlands with a long retention time

Space-time statistical analysis of malaria morbidity incidence cases in Ghana: A geostatistical modelling approach

Malaria is one of the most prevalent and devastating health problems worldwide. It is a highly endemic disease in Ghana, which poses a major challenge to both the public health and socio-economic development of the country. Major factors accounting for this situation include variability in environmental conditions and lack of prevention services coupled with host of other socio-economic factors. Ghana’s National Malaria Control Programme (NMCP) risk assessment measures have been largely based on household surveys which provided inadequate data for accurate prediction of new incidence cases coupled with frequent incomplete monthly case reports. These raise concerns about annual estimates on the disease burden and also pose serious threats to efficient public health planning including the country’s quest of reducing malaria morbidity and mortality cases by 75% by 2015.

In this thesis, both geostatistical space-time models and time series seasonal autoregressive integrated moving average (SARIMA) predictive models have been studied and applied to the monthly malaria morbidity cases from both district and regional health facilities in Ghana. The study sought to explore the spatio-temporal distributions of the malaria morbidity incidence and to account for the potential influence of climate variability, with particular focus on producing monthly spatial maps, delimiting areas with high risk of morbidity. This was achieved by modelling the morbidity cases as incidence rates, being the number of new reported cases per 100,000 residents, which together with the climatic covariates were considered as realisations of random processes occurring in space and/or time.

The SARIMA models indicated an upward trend of morbidity incidence in the regions with strong seasonal variation which can be explained primarily by the effects of rainfall, temperature and relative humidity in the month preceding incidence of the disease as well as the morbidity incidence in the previous months. The various spacetime ordinary kriging (STOK) models showed varied spatial and temporal distributions of the morbidity incidence rates, which have increased and expanded across the country over the years. The space-time semivariogram models characterising the spatio-temporal continuity of the incidence rates indicated that the occurrence of the malaria morbidity was spatially and temporally correlated within spatial and temporal ranges varying between 30 and 250 km and 6 and 100 months, respectively. The predicted incidence rates were found to be heterogeneous with highly elevated risk at locations near the borders with neighbouring countries in the north and west as well as the central parts towards the east. The spatial maps showed transition of high risk areas from the north-west to the north-east parts with climatic variables contributing to the variations in the number of morbidity cases across the country. The morbidity incidence estimates were found to be higher during the wet season when temperatures were relatively low whilst low incidence rates were observed in the warm weather period during the dry seasons.

In conclusion, the study quantified the malaria morbidity burden in Ghana to produce evidence-based monthly morbidity maps, illustrating the risk patterns of the morbidity of the disease. Increased morbidity risk, delimiting the highest risk areas was also established. This statistical-based modelling approach is important as it allows shortterm prediction of the malaria morbidity incidence in specific regions and districts and also helps support efficient public health planning in the country.

Geostatistical spatiotemporal modelling with application to the western king prawn of the Shark Bay managed prawn fishery

Geostatistical methodology has been employed in the modelling of spatiotemporal data from various scientific fields by viewing the data as realisations of space-time random functions. Traditional geostatistics aims to model the spatial variability of a process so, in order to incorporate a time dimension into a geostatistical model, the fundamental differences between the space and time dimensions must be acknowledged and addressed. The main conceptual viewpoint of geostatistical spatiotemporal modelling identified within the literature views the process as a single random function model utilising a joint space-time covariance function to model the spatiotemporal continuity. Geostatistical space-time modelling has been primarily data driven, resulting in models that are suited to the data under investigation, usually survey data involving fixed locations. Space-time geostatistical modelling of fish stocks within the fishing season is limited as the collection of fishery-independent survey data for the spatiotemporal sampling design is often costly or impractical. However, fishery-dependent commercial catch and effort data, throughout each season, are available for many fisheries as part of the ongoing monitoring program to support their stock assessment and fishery management. An example of such data is prawn catch and effort data from the Shark Bay managed prawn fishery in Western Australia. The data are densely informed in both the spatial and temporal dimensions and cover a range of locations at each time instant. Both catch and effort variables display an obvious spatiotemporal continuity across the fishing region and throughout the season. There is detailed spatial and temporal resolution as skippers record their daily fishing shots with associated latitudinal and longitudinal positions. In order to facilitate the ongoing management of the fishery, an understanding of the spatiotemporal dynamics of various prawn species within season is necessary. A suitable spatiotemporal model is required in order to effectively capture the joint space-time dependence of the prawn data. An exhaustive literature search suggests that this is the first application of geostatistical space-time modelling to commercial fishery data, with the development and evaluation of an integrated space-time geostatistical model that caters for the commercial logbook prawn catch and effort data for the Shark Bay fishery. The model developed in this study utilises the global temporal trend observed in the data to standardise the catch rates. Geostatistical spatiotemporal variogram modelling was shown to accurately represent the spatiotemporal continuity of the catch data, and was used to predict and simulate catch rates at unsampled locations and future time instants in a season. In addition, fishery-independent survey data were used to help improve the performance of catch rate estimates.

Geostatistical methods for estimating iron, silica and alumina grades within the hardcap of the section seven iron deposit, Tom Price

Many iron ore deposits have a weathered zone (Hardcap) near the surface which is highly variable in grades. Estimating the amount of ore grade material (HG) in this zone is difficult as a result of this variability. The Section Seven Deposit at Tom Price is largely mined out and has production data available in the form of grade blocks that were marked out during mining as HG and non- HG. Hardcap domains and a block model representing them were created and estimates were made from original exploration data using Ordinary Kriging, Global Change of Support, Indicator Kriging and Median Indicator Kriging techniques. The estimates were compared to the production data The production data total HG blocked out was 6.4 Mt and the best central estimator of ore was Ordinary Kriging (2.0 Mt). Indicator and Median Indicator Kriging E-type estimates of ore were very similar at ~ 1.6 Mt. The Global Change of Support estimate was 4.0 Mt. An effective way of seeing the excessive smoothing in the central estimates was to compare the grade tonnage curves. All the central estimate of grades (OK, IK and Median IK E-type) were inaccurate and over smoothed. Given good quality samples and assays as well as sound estimation parameters the accuracy of these methods fundamentally comes down to the amount of data available to estimate from. There is insufficient data to get accurate estimates using these techniques. The main information that Indicator Kriging provides is not the E-type estimate but an estimate of the distribution of grades for each block from which a pseudo-probability that the block is HG can be derived. The pseudo probability was used to create maps of HG at different probability levels and there was a good match visually and between the production data HG blocks and blocks that had a greater than 0 chance of being HG. In comparison to the maps of HG generated from Ordinary Kriging which feature very few HG blocks and many sub-HG blocks these are a great improvement. Median Indicator Kriging was just as effective as Indicator Kriging in this regard, which is an important point as the former is less work than the later. Quantitative reconciliation of the Median Indicator Kriging results against the production data showed that blocks with a probability of 0.3 of being HG totalled 6.7 Mt and 49% of this matched HG production data. This gives rise to a methodology as follows: If OK has been used in estimating hardcap and if the Global Change of Support estimate indicates that there is a risk of oversmoothing with regard to the HG cut-off then Median IK should be used to identify areas which have a chance of being HG and then deciding on the best way to take advantage of this information. Some possibilities would be to:

target these areas for closer spaced drilling in order to generate an improved OK estimate;

use the area defined above to sub-domain the hardcap and re-estimate using OK;

target these areas for mining first as they have a good chance of being HG.

Plurigaussian Simulation of rocktypes using data from a gold mine in Western Australia

Stochastic simulation of rocktypes, or the geometry of the geology, is a major area of continuing research as earth scientists seek a better understanding of an orebody as a precursor to the assignment of continuous rock properties, allowing more economically appropriate decisions regarding mine planning. This thesis analyses the suitability of particular geostatistical rock type modelling algorithms when applied to the five rocktypes evident in drill hole data from the Big Bell gold mine near Cue, Western Australia. The background of the geostatistical theory is considered, in particular the concept of the random function model and the link between the categorical statistics determined from the drill hole data and the three models used for estimation and simulation. The commonly applied indicator kriging (IK) and sequential indicator simulation (SIS) algorithms are compared in a non-sedimentary gold deposit environment to the more computationally demanding and more complex plurigaussian simulation (PGS). Comparisons between the three models are made by examining global and regional rocktype (lithotype) proportions of the outputs of the models, both visually and empirically. The models are validated by considering the contacts which occur in reality between different lithotypes and the proportion of contacts which do not conform to this reality in each of the models. This „inadmissible contact‟ ratio measures the short range validity of the estimation and simulation techniques. Finally, cores taken from the output of the models are compared to the drill hole data in terms of transition proportions between the twenty five possible transitions for the five lithotypes. Inadmissible contacts were at a minimum with PGS, and the visual and empirical natures of the PGS output were closely linked to the reality of the drill hole data. Whilst each model produced similar 3D images, PGS was a realistic balance between the clustering effect produced by IK and the fine mosaic effect from SIS. The PGS output numerically outperformed the other two models in terms of admissible contacts and connectivity, most closely matching the drill hole data. All results indicate that, whilst demanding to implement, PGS produces the most adequate model of the study region.

Australia's oil refining industry - Importance, threats and emergency response

Australia is heavily reliant on down-stream, or refined oil products for daily life and industrial purposes. The industry faces a range of threats and risk factors all of which have the capability to inflict significant damage. A major disruption to Australia's oil refining industry would have major consequences not only for the industry but on society and the economy as a whole. By assessing Australia's reliance on oil products, as well as considering the impact of major disruption to oil refining capabilities internationally, this paper seeks to assess the impact that such an event would have on Australian society, public and private industry and the economy. In the Australian context the industry is not adequately prepared to respond to, or recover from major disaster or disruption. There are a range of international strategies and policies which will be assessed in order to further prepare the Australian industry for a range of potential disasters. This paper uses the Kwinana oil refinery in Western Australia as a case study for considering potential threats, consequences and recovery strategies related to a major oil refinery disruption or disaster.

https://ro.ecu.edu.au/ecuworks/1130

Comparison of three survey methods applied to the recreational rock lobster fishery of Western Australia.

A mail survey of recreational rock lobster licence holders has been conducted annually since 1986. The results from this survey have been used in the management of the recreational rock lobster fishery in Western Australia. Mail surveys are susceptible to non-response and recall bias. The key to determining useful estimates of fishing catch and effort is to minimise both biases. Telephone recall surveys, with high response rates, effectively eliminate nonresponse bias. However, they still suffer from recall bias when the recall period is greater than two months. Telephone diary surveys are free of non-response bias and recall bias and provide the most accurate estimates of effort and catch. In the 2001/02 season three independent surveys were conducted to estimate the recreational catch and fishing effort of the 37,000 fishers licensed to fish for rock lobsters.

The solution of traffic signal timing by using traffic intensity estimation and fuzzy logic

This study aims at calculating the traffic signal timing that suits traffic intensity at intersections studied in the inner city of Ubon Rachathani Provice, Thailand. The mixed models between maximum likelihood estimation and Bayesian inference are presented to estimate traffic intensity. A queuing system is used to generate the performance of traffic flow. A fuzzy logic system is applied to calculate the optimal length of each phase of the cycle. The fortran language is used to produce the computer program for computation. The algorithm of the computer programming is based on EM algorithm, Markov Chain Monte Carlo algorithm, queuing generation and fuzzy logic. The output of traffic signal timing from the fuzzy controller are longer than the traffic signal timing from the conventional controller. Cost function is used to evaluate the efficiency of the traffic controller. The result of the evaluation shows that fuzzy controller is more efficient than a conventional controller.

Public street surveillance: A psychometric study on the perceived social risk

Public street surveillance, a domain of Closed Circuit Television (CCTV), has grown enormously and is becoming common place with increasing utilization in society as an all-purpose security tool. Previous authors (Ditton, 1999; Davies, 1998; Horne, 1998; Tomkins, 1998) have raised concern over social, civil and privacy issues, but there has been limited research to quantify these concerns. There are a number of core aspects that could relocate the risk perception and therefore, social support of public street surveillance. This study utilized the psychometric paradigm to quantitatively measure the social risk perception of public street surveillance. The psychometric paradigm is a method that presents risk perception in a two factor representation, being dread risk and familiarity to risk. Four additional control activities and technologies were tested, being radioactive waste, drinking water chlorination, coal mining disease and home swimming pools. Analysis included spatial representation, and multidimensional scaling (MDS) Euclidean and INDSCAL methods. The study utilized a seven point Likert scale, pre and post methodology, and had a target population of N=2106, with a sample of N=135 (alpha=0.7).
