An ‘expert system’ approach to the assessment of the conservation status of rivers

This paper describes the aims and development of a computerised system for the assessment of conservation status in South African rivers. The system is designed to: (a) facilitate the communication of river conservation priorities to managers, developers and planners; (b) provide a consistent but flexible method for classifying rivers according to their conservation status; (c) act as a semi-numerical model to simulate the effects of proposed development plans on specific rivers. The system is written in PROLOG to run on an IBM PC, employing ‘expert system’ techniques. The user is asked to provide information in response to questions about specific attributes of a river (e.g. number of indigenous fish species, amount of sewage effluent, etc.). These attributes were compiled and weighted in consultations with all river ecologists and professional conservationists working on rivers in South Africa. Attribute weightings are modified by a series of rules (e.g. related to the size of the river), and an overall score between 0 and 100 for the conservation status of the river is calculated. In addition, the system provides a breakdown of scores by biota, catchment and the river itself, and by individual attribute. Confidence limits indicating the level of available information are calculated, and those attributes of greatest interest for the conservation of the river are identified, as are those attributes most urgently requiring further research.