Townley, L.R., and Trefry, M.G. (1991). Two- and three-dimensional modelling of groundwater flow through the Koongarra uranium orebody, IN: Alligator Rivers Analogue Project, 2nd Annual Report 1989-90, ANSTO, 115-132.

Before commencing any modelling exercise, we need to identify the questions which modelling may help to answer. In the context of ARAP, the questions at Koongarra revolve around the direction and rate of groundwater flow, under present and past climatic conditions, which in combination with other physical and chemical dynamical processes have resulted in a dispersion zone downgradient of the primary orebody.

A popular view would be that groundwater flow can not be considered in isolation from dispersion processes, which in turn can not be considered in isolation from chemical solution/dissolution or adsorption/desorption processes. It is conceptually possible to model all processes simultaneously, but in practice, even if suitable software could be found, the computational requirements would far exceed those available. It is therefore necessary to model different processes separately, taking other processes into account in some external and intuitively reasonable way.

This report summarizes the results of groundwater flow modelling carried out by the CSIRO Division of Water Resources between September 1989 and September 1990. The aims of our component of ARAP are specifically to develop a three-dimensional groundwater flow model under present climatic conditions.