ABSTRACT
This chapter focuses on methodological developments in environmental impact assessment (EIA), all of which attempt to come to grips with the vast, interactive scale of the environment, and the subsequent volume of information generated in even the simplest environmental assessment. One of the simplest methodologies of EIA is overlay mapping, a common technique in land use planning wherever the chief concern is locating a project or a route alignment in physical space. The geographical area under concern is divided into grid cells, and demographic information and various physical characteristics are represented graphically on transparent maps divided into the spatial units. The most recent of EIA techniques involves the use of dynamic simulation procedures which structure causal models to reflect interactions between environmental variables. Qualitative simulation models may only require the user to specify whether the relationship between relevant system variables is positive, negative, or nil, or they may be complex and require data on the relative magnitude of interaction effects.
