In this paper, on the GIS Development site, a methodology is presented that utilises GIS to quantify the spatial geologic data and statistical analysis to determine the relation between groundwater quality parameters and geological units. The methodology is illustrated through an application to a study area located in the Western Indian Aquifer (WIA) system. The areal extents of geologic units in the study area are identified and their spatial distributions are quantified using GIS. The spatial extents of identified geological units are then correlated with the groundwater quality parameters using statistical analysis.

The increasing amount of multiple data sets being made available from various sources has created a need for efficient capture, storage, management, retrieval and analysis of geoenvironmental data to address various groundwater pollution problems of varying nature, dimension and complexity, cropping at local, regional and basin scale worldwide. Geographic Information System (GIS) has emerged as an effective tool for relating and integrating vast volumes of different data types, obtained from different sources and compiled on different scales.

Results reveal that there is a high negative correlation between calcium and ultrabasic rock, a high positive correlation between fluoride and ultrabasic rock, a moderately high positive correlation between bicarbonate and ultrabasic rock, and a very high positive correlation between pH, gneiss and schists. Such studies within GIS environment help in better understanding of the water-rock interactions, and thus will prove useful in formulating numerical models to study transport mechanisms of various chemical species in different hydrogeologic and chemical environments.