Boughton, G.N., Townley, L.R., and Perkins, G.P. (1986), Large-scale modelling of the unconfined aquifer system underlying Perth, Western Australia, International Conference on Groundwater Systems under Stress, Brisbane, May 1986.

A numerical model has been developed for predicting the behaviour of the unconfined aquifer underlying Perth, Western Australia. The model uses a large regional data base and then couples a conceptual Vertical Flux Model with a saturated Aquifer Flow Model. The regional data base contains data for an area 30km by 100km, with grids of 100m and 500m spacings for different variables which affect the regional water balance. A Vertical Flux Model has been developed which accounts for rainfall, septic tank effluent, road drainage, roof drainage, garden and crop irrigation, evapotranspiration, extraction by bores, and leakage to or from the underlying confined aquifer. In order to adequately represent the spatial variation of vertical flux into the aquifer, it operates on 100m x 100m cells. The Aquifer Flow Model uses triangular finite elements and operates on a much coarser scale. This paper presents the philosophy of model development, pertinent details of the model, and comments on its use for analysis of a portion of the Perth urban area.