Evaluation of groundwater pollution risk (GPR) from agricultural activities using DRASTIC model and GIS

Abstract

Groundwater Pollution risk (GPR) map which utilized groundwater quality is important in order to prevent the groundwater contaminant concentration due to the agricultural activities. DRASTIC model and GIS application are two important tools that had been used for accessing and predicting the quality of groundwater. These supplementary tools are calculating, visualizing, and presenting the GPR by using DRASTIC index for each hydrogeologic factor through ArcGIS software. This study was covered approximately Selangor basin area where the GPR has been defined. There are four categories of agricultural activities in the Selangor basin which are animal husbandary areas, horticultural lands, short term crops and tree, palm and other permanent crops. The map showed that the “low” zones of GPR occupied 56% of the east side of the Selangor basin, 34% of the west side of the Selangor basin exposed to “medium” zones of GPR and the “high” zones of GPR covered 10% at the north side and the south to the west side of the Selangor basin. As a particular, for agricultural activities which is 52% of Selangor basin area, the “low”, ‘’medium” and “high” zones of GPR was occupied as 42%, 43% and 15% respectively. Based on four categories of agricultural landuse, GPR map validated by nitrate distribution map, shows that the 99% of the variation in nitrate distribution zones are explained by GPR zones. In conclusion, groundwater pollution risk was affected by agricultural activities.