School of Geography - Theses
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ItemUrban road traffic noise and health( 2000)Some people say they are annoyed by traffic noise. There is rather a lot of evidence to show that where traffic noise is louder, more people say they are annoyed by it. On the basis of this sort of evidence, there is a consensus that road traffic noise causes annoyance. Traffic noise is also suspected of being dangerous to health: of making people ill; so ill they reach for painkillers or even visit a doctor to get medicine prescribed. The fundamental aim of this thesis is to find out whether this is happening in Melbourne. The available evidence contains anomalies: people seem to be healthy where noise is loudest. Even annoyance studies sometimes detect unexplained peaks of annoyance in quieter places; or a plateau of annoyance in high noise. However, the anomalies display a certain consistency. Traffic noise is orthodoxly measured by loudness. Several studies have found a peak of annoyance at around 60 decibels. The consistency of the anomalies suggests that some other physical characteristic of noise may be responsible for the anomalous responses. This thesis sets out to explore the urban soundscape in an attempt to find such a characteristic, and discovers the pattern of alternation of passby noise and background sound: passby patterns. The orthodox loudness measure is essentially a proxy for the daily average sound energy delivered to the ear by traffic. To define patterns requires taking this measure apart - splitting traffic noise into two sounds: the sound of passbys and the background sound. The definition builds up through the use of point source theory, observations in urban and rural environments, experiments with a typical sedan in isolated locations, and experimentation with techniques for the measurement of background sound generated by roads. The tools applied are ears, stopwatch and sound meter. The result is a set of techniques aimed to measure patterns of passby noise in urban environments. Application of these techniques at 102 randomly selected sites spread over 150km2 of urban environments detects passby patterns in Melbourne. By way of an example, the final stage of this investigation embeds pattern measurements within a small, orthodox study of the annoyance and health responses to traffic noise measured by decibels. The results are consistent with regular or rapidly alternating passby patterns being closely associated with annoyance and ill health. In particular, in relation to people who are sensitive to noise, it should no longer be assumed that peak distress at approximately 60dB(A) is anomalous. It may well be due to high levels of patterning of passby noise. The result requires confirmation, to be sure, but the evidence is sufficiently strong to suggest that traffic noise and patterns of passby noise, or something closely associated with them, are probably associated with health problems in Melbourne.
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ItemDenudation along a passive margin: a study from southeastern Australia( 1994)This thesis reports the results obtained and conclusions made regarding research into the isostatic effects of denudation and deposition on the post-rifting morphological evolution of the southeast Australian margin. The temporal and spatial variation of denudation since 125 Ma is quantified using geomorphological and apatite fission track analysis (AFTA) data. Depositional data for the Gippsland Basin is derived from isopach maps. Reference surfaces for the volumetric calculations of material removed and deposited are based on 2 x 2 km gridded data. On the basis of modelling the thermal and mechanical effects of denudation on the thermal structure of the lithosphere it is assumed that rifting related thermal overprinting did not occur in the AFTA samples. Hence the estimated thicknesses of crustal section removed by denudation are maxima. The denudation and deposition data are used as applied loads in one- and twodimensional continuous elastic plate models to determine the isostatic response of the margin. Results on the spatial and temporal variation of denudation indicate that from 125 Ma to 60 Ma a maximum of 3.6 km of crustal section has been removed from the southeast Australian margin. The amount of material removed generally decreases from the coast inland, supporting a model of margin evolution where the morphology of the margin is largely the result of the retreat of a major erosional escarpment. Rates of denudation have varied considerably in the last 125 Ma, suggesting that previously argued post Cretaceous landscape stability for the area is incorrect. The isostatic response of the margin suggests that within the limitations of the model used, the morphological evolution of the margin can be explained without the need for postrifting tectonic surface uplift. The maximum amount of surface uplift generated by the escarpment retreat model is in the order of 500 m along the boundary between the elevated tablelands and the escarpment. Deposition in the Gippsland Basin does not significantly change the amount of predicted surface uplift, however, it does change the spatial distribution of the uplift. Evidence from the Towamba and Snowy River valleys suggests that escarpment retreat has been slowed considerably since the early Tertiary. This may be due to changes in the drainage pattern of the margin associated with the uplift of the Kosciusko Block and river capture. The results provide some answers to contentious issues raised by geomorphologists and thermochronologists about the timing of uplift and overall morphological evolution of the southeast Australian margin. These conflicts appear to be largely due to differences in terminology and definitions, as well as extrapolations of results beyond the constraints of the data.