ABSTRACT
Geographical information systems (GIS) are increasingly being used for inventory, analysis, understanding, modelling and management of the natural environment (Bouma and Bregt, 1989; Burrough, 1986; Goodchild et al., 1993, 1996; Maidment, 1993, 1995). Environmental modelling has at least two distinct aims (Moore et al., 1993): (a) to help understand the physical world, and (b) to provide a predictive tool for management. Scientists use models to understand the natural world better and their models may be complex. Simple models may enable managers to make useful predictions but may be less detailed than scientists would like. In recent years many environmental agencies have seen GIS as a way to link numerical models to spatial databases to provide both understanding and prediction in the form of attractive, easy-to-read graphs, maps, and multimedia demonstrations.
