Infrastructure Engineering - Research Publications
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ItemThe behavior of stratified pools in the Wimmera River, Australia(AMER GEOPHYSICAL UNION, 1996-10)Numerous inland Australian streams contain density‐stratified or saline pools, which are usually located on channel bends. Saline pools consist of a layer of saline water underlying a layer of fresh water. Saline pools generally form as a result of saline groundwater seeping into the stream and collecting in scour depressions during periods of low flow. Inflows of saline river water can also collect in scour depressions. Field and laboratory investigations of saline pool mixing by overflowing fresh water reveal that mixing depends on a balance between interfacial shear and buoyancy forces acting on a thin dense layer flowing up the downstream slope of the scour depression, and on the bend sharpness. Convection associated with surface cooling also causes mixing. A model for saline pools formed by groundwater inflows and mixed by fresh overflows is proposed and applied to several saline pools in the Wimmera River.
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ItemPreferred states in spatial soil moisture patterns: Local and nonlocal controls(AMER GEOPHYSICAL UNION, 1997-12)In this paper we develop a conceptual and observational case in which soil water patterns in temperate regions of Australia switch between two preferred states. The wet state is dominated by lateral water movement through both surface and subsurface paths, with catchment terrain leading to organization of wet areas along drainage lines. We denote this as nonlocal control. The dry state is dominated by vertical fluxes, with soil properties and only local terrain (areas of high convergence) influencing spatial patterns. We denote this as local control. The switch is described in terms of the dominance of lateral over vertical water fluxes and vice versa. When evapotranspiration exceeds rainfall, the soil dries to the point where hydraulic conductivity is low and any rainfall that occurs essentially wets up the soil uniformly and is evapotranspired before any significant lateral redistribution takes place. As evapotranspiration decreases and/or rainfall increases, areas of high local convergence become wet, and runoff that is generated moves downslope, rapidly wetting up the drainage lines. In the wet to dry transitional period a rapid increase in potential evapotranspiration (and possibly a decrease in rainfall) causes drying of the soil and “shutting down” of lateral flow. Vertical fluxes dominate and the “dry” pattern is established. Three data sets from two catchments are presented to support the notion of preferred states in soil moisture, and the results of a modeling exercise on catchments from a range of climatic conditions illustrate that the conclusions from the field studies may apply to other areas. The implications for hydrological modeling are discussed in relation to methods for establishing antecedent moisture conditions for event models, for distribution models, and for spatially distributing bulk estimates of catchment soil moisture using indices.
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ItemThe Tarrawarra data set: Soil moisture patterns, soil characteristics, and hydrological flux measurements(AMER GEOPHYSICAL UNION, 1998-10)Experiments investigating the spatial variability of soil moisture conducted in the 10.5 ha Tarrawarra catchment, southeastern Australia, are described. The resulting data include high‐resolution soil moisture maps (over 10,000 point measurements at up to 2060 sites), information from 125 soil cores, over 1000 soil moisture profiles from 20 sites, 2500 water level measurements from 74 piezometers, surface roughness and vegetation measurements, meteorological and hydrological flux measurements, and topographic survey data. These experiments required a major commitment of resources including 250 person days in the field, with a further 100 person days in the laboratory preparing for field trips and checking and collating data. These data are available on the World Wide Web (http://www.civag.unimelb.edu.au/data/).
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ItemObserved spatial organization of soil moisture and its relation to terrain indices(AMER GEOPHYSICAL UNION, 1999-03)We analyze the degree of spatial organization of soil moisture and the ability of terrain attributes to predict that organization. By organization we mean systematic spatial variation or consistent spatial patterns. We use 13 observed spatial patterns of soil moisture, each based on over 500 point measurements, from the 10.5 ha Tarrawarra experimental catchment in Australia. The measured soil moisture patterns exhibit a high degree of organization during wet periods owing to surface and subsurface lateral redistribution of water. During dry periods there is little spatial organization. The shape of the distribution function of soil moisture changes seasonally and is influenced by the presence of spatial organization. Generally, it is quite different from the shape of the distribution functions of various topographic indices. A correlation analysis found that ln(a), where a is the specific upslope area, was the best univariate spatial predictor of soil moisture for wet conditions and that the potential radiation index was best during dry periods. Combinations of ln(a) or ln(a/tan(β)), where β is the surface slope, and the potential solar radiation index explain up to 61% of the spatial variation of soil moisture during wet periods and up to 22% during dry periods. These combinations explained the majority of the topographically organized component of the spatial variability of soil moisture a posteriori. A scale analysis indicated that indices that represent terrain convergence (such as ln(a) or ln(a/tan(β))) explain variability at all scales from 10 m up to the catchment scale and indices that represent the aspect of different hillslopes (such as the potential solar radiation index) explain variability at scales from 80 m to the catchment scale. The implications of these results are discussed in terms of the organizing processes and in terms of the use of terrain attributes in hydrologic modeling and scale studies. A major limitation on the predictive power of terrain indices is the degree of spatial organization present in the soil moisture pattern at the time for which the prediction is made.
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Item[Review of the book Fermat's last theorem](The Victorian Bar, 1997)Two recent books celebrate the long sought solution of a venerable maths problem.
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Item[Review of the books Skunk works: a personal memoir of my years at Lockheed and The story of Webster's Third: Philip Gove's controversial dictionary and its critics](The Victorian Bar, 1995)Description of two creative men and their work products – innovative top secret US military aircraft and the current edition of Webster’s Third New International Dictionary.
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ItemGroundwater Quality Hydrogeological Assessments( 1999)Groundwater is a vital resource in Victoria. The Environment Protection Authority (EPA) and other authorities recognise the need to protect the quality of groundwater as a resource and as part of the natural environment. Hydrogeological Assessments (HAs) is one of the tools used to provide the information necessary to determine the status of groundwater quality or the effects of a proposal on the beneficial uses of groundwater. For example, a proponent of a new landfill or industrial development with potential to impact groundwater is likely to be required to perform a HA. The HA guidelines that have been published by EPA (EPA publication 668) provide an overview of HA methodologies, and the reasons for using different investigative techniques. The document presented here is a background document. It was commissioned and funded by the EPA; however it was never published by EPA. Instead, this document formed the basis for development of the guidelines, Hydrogeological Assessments (Groundwater Quality) Guidelines, published by EPA in August 2006.
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ItemImplementing LIS/GIS from a customary land tenure perspective: the Fiji experience( 1995)This paper briefly reviews Fiji's national land information system (LIS) strategy and the major land and geographic information systems (LIS/GIS) initiatives that have been under way in the major government organisations in Fiji up to April 1994. It also describes and attempts to examine the impact that these initiatives have had on the people who continue to live under Fiji's customary land tenure systems.
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ItemImplications of incorporating Customary Land Tenure Data into a Land Information System( 1995)Land Information Systems (LIS) have been primarily developed to serve the needs of countries that use a 'western' style land market where individual land rights are the norm. However many countries that have a large proportion of lands held under customary land tenures where communally held land rights are common, are also wishing to establish LIS. For these countries LIS is a tool to facilitate the management and administration of their land resources, preserve their customs and traditions and promote the development of a market economy. In order to be effective, the LIS introduced into these countries will need to incorporate customary land tenure data. This paper considers the implications of incorporating such customary land tenure data into a LIS.Firstly the attributes of western land tenures that are currently used in Land Information Systems are reviewed; then drawing examples from Fiji, the paper examines some of the attributes of customary tenure that could be entered into a LIS. This is followed by a discussion of some of the major issues associated with including customary tenure data into a LIS.
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ItemTraditional land tenure issues for LIS in Fiji( 1995)With the help of the New Zealand Government, a national LIS is currently being implemented in Fiji, under the auspices of the Department of Lands. Like many other Pacific Island countries, Fiji has a complex land tenure system. This is the first of two papers that aims at examining the implications of LIS for traditional land tenures. Since LIS is a product of the industrialised world, attributes of the conventional `western' land tenures can easily be incorporated into any LIS. However, attributes of traditional land tenures are yet to be identified and incorporated into an LIS. Unless traditional land tenure issues are considered and taken into account when implementing an LIS, the LIS will not be fully accepted and utilised by the traditional peoples, and will therefore not be truly successful. The emphasis in these papers therefore will be on the traditional aspects of land tenure. This paper reviews Fiji's dual land tenure systems, with particular emphasis on it's traditional land tenure system, and raises some issues and problems of it for an LIS.