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Abstract: In this paper, a two-dimensional control volume finite-element computational model is developed for simulating saltwater intrusion in a heterogeneous coastal alluvial aquifer system at Gooburrum located near Bundaberg in Queensland, Australia. The model consists of a coupled system of two non-linear partial differential equations. The first equation describes the flow of a variable-density fluid, and the second equation describes the transport of dissolved salt via a form of the Fokker–Planck equation. The outcomes of the work demonstrate that transport simulation techniques provide excellent tools for hydraulic investigations even when complex transition zones are involved. [Copyright &y& Elsevier]

Abstract. The supermarket equation is a differential equation peculiar to spatial science. The complex form of this equation is presented here and is used to study aggregate consumer shopping patterns. The locus is the relationship between trips to, and shopping within, planned shopping centres relative to retail trading hour boundaries. In this context, five malls in Sydney are studied in the period prior to the introduction of deregulated shopping hours in 1992. The space-time convergence of aggregate consumer behaviour at these retail nodes show that the gravity coefficient can be treated in a temporal context. Estimates of mean trading hours can be made from the general solution and these are compared to alternative estimates from Fourier analysis. Time corrections to the gravity coefficient allow for a dynamic market area analysis, where the primary trade area can be determined relative to the trading hours of the shopping centre. A Sydney example shows how this methodology can be applied with population census data. [ABSTRACT FROM AUTHOR]

This paper examines the conditions under which an empirical model of employment choice based on the differential in current earnings is an adequate specification when the theoretical model suggests the use of the difference in present values of the stream of lifetime earnings. The difference between the two approaches is shown to be variables for the growth rates of earnings in the employment states over which choice is being made. [ABSTRACT FROM AUTHOR]

Guard, P., Teakle, I., Nielsen, P. and Baldock, T.E., 2007. Modelling Sheet Flow Sediment Transport Using Convolution Integrals. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 937 – 942. Gold Coast, Australia, ISSN 0749.0208 A new method for the prediction of instantaneous sediment transport rates is presented based on the use of convolution integrals. The convolution integral technique allows solution of the governing differential equations in the time domain while accurately representing important unsteady flow effects. This technique overcomes many of the limitations of simple quasi-steady sediment transport models and does not require the computational effort of more detailed process-based models. The present model has been parameterised using results from a more detailed process-based two-phase model. Preliminary results indicate that the technique is successful in predicting net transport rates in oscillatory flow tunnel experiments in the sheet flow regime. Extension of the model to other sediment transport regimes and incorporation of real-wave effects such as boundary layer streaming is possible. [ABSTRACT FROM AUTHOR]