Infrastructure Engineering - Research Publications

Permanent URI for this collection

Search Results

Now showing 1 - 10 of 103
  • Item
    Thumbnail Image
    The behavior of stratified pools in the Wimmera River, Australia
    Western, AW ; ONeill, IC ; Hughes, RL ; Nolan, JB (AMER GEOPHYSICAL UNION, 1996-10-01)
    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.
  • Item
    Thumbnail Image
    Preferred states in spatial soil moisture patterns: Local and nonlocal controls
    Grayson, RB ; Western, AW ; Chiew, FHS ; Bloschl, G (AMER GEOPHYSICAL UNION, 1997-12-01)
    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 s 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.
  • Item
    Thumbnail Image
    The Tarrawarra data set: Soil moisture patterns, soil characteristics, and hydrological flux measurements
    Western, AW ; Grayson, RB (AMER GEOPHYSICAL UNION, 1998-10-01)
    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/).
  • Item
    Thumbnail Image
    Observed spatial organization of soil moisture and its relation to terrain indices
    Western, AW ; Grayson, RB ; Bloschl, G ; Willgoose, GR ; McMahon, TA (AMER GEOPHYSICAL UNION, 1999-03-01)
    The degree of spatial organization of soil moisture, and the ability of terrain attributes to predict that organization was analyzed. The measured soil moisture patterns exhibited a high degree of organization during wet periods due to surface and subsurface lateral redistribution of water. The shape of the distribution function of soil moisture changed seasonally and was influenced by the presence of spatial organization. A correlation analysis found that ln(a), where a is the specific unslope area, was the best univariate spatial predictor of soil moisture during wet periods and up to 22% during dry periods.
  • Item
    Thumbnail Image
    Segmentation of Visually Similar Textures by Convolution Filtering
    Benke, K ; SKINNER, DR (Australian Computer Society, 1987-08-01)
    We describe an approach to texture segmentation designed for the extraction of a textured object from a textured background. The approach assumesthatno information is available on the objecttexture butthat a prior analysis ofthe background texture has been undertaken. The power ofthe approach is demonstrated on a texture composite for which object extraction and identification is almost impossible by visual inspection.
  • Item
    Thumbnail Image
    [Review of the book Fermat's last theorem]
    Lewin, E. ; Park, M. M. (The Victorian Bar, 1997)
    Two recent books celebrate the long sought solution of a venerable maths problem.
  • Item
    Thumbnail Image
    [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]
    Park, Malcolm McKenzie (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.
  • Item
    Thumbnail Image
    Groundwater Quality Hydrogeological Assessments
    Lane, Mr Anthony ; Leonard, Mr John ; Weaver, Dr Tamie R ( 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.
  • Item
    Thumbnail Image
    The cadastral survey requirements of developing countries in the Pacific region: with particular reference to Fiji
    Williamson, Ian P. (Commonwealth Association of Surveying and Land Economy (CASLE), 1982)
    The cadastral survey systems introduced into many developing Pacific countries during colonial eras often do not meet the social and economic demands placed on them at the present time. Such systems can seriously limit the availability and transfer of land hence restricting the development and economic advancement of a country .This paper considers the subject generally although particular reference is made to the system presently operating in Fiji.
  • Item
    Thumbnail Image
    Cadastral survey techniques in developing countries: with particular reference to Thailand
    Williamson, Ian P. ( 1983-09)
    The benefits of an efficient cadastral, survey and land registration system to developing countries are described. The legal, and particularly the technical procedures in creating a cadastre are discussed. The use of ground and photogrammetric survey techniques are highlighted. The reasons for restricting, the introduction of efficient cadastral survey systems are considered. Thailand is used as an example of a country which has, shown much flexibility in improving its cadastral system to better meet the needs of its developing economy. In this regard, the institutional and legal arrangements in the Thai cadastral system are described, as is the development of the cadastral survey system. As an indication of continuing flexibility, the future direction of 1he Thai cadastral, system is discussed.