Assessment of pollution risk requires the assimilation of spatio-temporally variable data on water quality parameters. This paper describes a GIS user-interface program coupled with a water quality index (WQI) model that was developed and built to assess water quality in the Sg. Buloh river basin. Fifty-two water sampling stations were selected for this study, and the WQI model considers parameters such as pH, dissolved oxygen, biochemical oxygen demand, chemical oxygen demand, total suspended solids and ammonia nitrogen, as used by the Department of Environment in Malaysia. The spatial pattern of each parameter was analysed, and WQI values were calculated, ranging from 4.48 to 76.8 on a scale with 100 representing the highest pristine quality. A map of WQI is provided, which will help planners and decision makers to develop water pollution control strategies, and the model is capable of extension with further data to address pollution risk.
Keywords: assessment, water quality, GIS user-interface, interactive system