Groundwater geochemical mapping in hard rock area of Gadilam river basin using GIS technique, Tamil Nadu, India

To represent groundwater quality of upper Gadilam river basin, groundwater samples were collected from field. Twenty groundwater samples were collected during premonsoon season in the year 2007 to infer the major ion geochemistry of the study area. Present work aims to interpolate major ions concentration in groundwater by using ARC/view GIS software. Major element thematic maps on calcium, magnesium, alkalies’, bicarbonates, chlorides and sulphates were prepared from the hydrochemistry data. Different classes in thematic maps were categorised as (i) good (ii) moderate and (iii) poor. Poor ground water suitable zones as per sulphate concentration are found to occur as a small enclosure in the eastern part near the village Kuchipalayam.