Identification of hydrogeochemical processes in the Coimbatore district,Tamil Nadu,India

ABSTRACT

Hydrogeochemical investigations were carried out with an objective to identify the processes affecting the chemistry of groundwater in the Coimbatore district of Tamil Nadu, India. Thirty-three groundwater samples were collected from representative wells for chemical analysis. Groundwater types identified from piper plots were Ca-Mg-Cl and Na-Cl. The dominance of ions was in the order of Na>Ca>Mg>K and Cl>HCO₃>SO₄>CO₃. Spatial variation diagrams of ions were generated using the geostatistical analyst tool ArcGIS 9.3. According to these diagrams, most of the ions were higher in the northeast and southeast regions. This is attributed to the flow direction of the groundwater and high residence times. Gibbs diagrams identified rock–water interaction as an important geochemical process in the district. Evaporation, ion exchange, silicate weathering and dissolution of carbonate minerals were identified as other important hydrogeochemical processes which influence the groundwater chemistry of the study area.

EDITOR D. Koutsoyiannis ASSOCIATE EDITOR M. Besbes