Groundwater Management Action Plan-stage 3. Characterising and prioritising groundwater pollution threats - decision support system tool.
A simple decision-support system (DSS) has been developed to help the non-specialist characterise and prioritise groundwater pollution threats according to their type, source, severity, scale, and possible impact on different end uses and users. The DSS is available in both electronic (Excel 97spreadsheet) and manual (paper copy) forms. The latter is based on the tables presented in Decision Support Tables, with results computed manually. Instructions on how to work through both versions are given in the User Guide below.
Specifically, the DSS draws on the data generated by the Urban Groundwater Questionnaire and a series of 'lookup' and 'cross-tables' to determine:
(a) the type of contaminants that might be produced in different cities, based on a classification of urban activities and information on wastewater disposal arrangements.
(b) which of these contaminants are likely to reach the water table, based on typical aquifer travel times and contaminant persistence.
(c) how widespread and severe the resulting contamination might be, based on contaminant typeand the hydrogeological environment.
(d) whether the contamination problem, or hazard, poses a threat to different end users/uses, and how soon the use/user might be affected.
The DSS can be used to assess future risk to urban groundwaters, and to help characterise existing problems. In the latter case, for example, the DSS could be used to guide monitoring efforts and identify likely contamination sources where groundwater quality has already deteriorated. In this respect it complements, rather than substitutes for, direct monitoring of resource conditions.
In its present form, the DSS does not provide detailed information on (d) above. The emphasis is on characterising pollution threats, rather than working through context-specific policy options.