MEXSES: an expert system for environmental screening

A rule-based expert system for environmental impact assessment is described which was implemented for the analysis of water resources development projects. The system uses hierarchical checklist questionnaires, organized by project types and problem classes, and an assessment procedure based on rules and descriptors that allow the analyst to classify subproblems in terms of their expected environmental impacts and to aggregate them into an overall project assessment. Rules and descriptors are linked with cross-references. The inference engine uses look-ahead preprocessing for the dynamic pruning of the inference tree, and offers both forward and backward chaining functions for standard problem assessment and an alternative hypothesis testing feature. Different modes of interaction, all based on a fully menu-driven graphical user interface implemented in X Windows, offer alternative levels of verbosity with the optional display and selection of rules by the user. The software system includes a project database and an integrated geographical information system for the management of spatial environmental data