Characterization of weathering profile and quality of groundwater over hard rock terrain

Abstract

In this study, we present a detailed characterization of weathering profile and groundwater over a hard rock terrain showing the formation of kaolinite, groundwater quality assessment, and hydrogeochemistry. The crystal structure, chemical composition, and spectral characteristics of a weathering profile collected from Thiruvananthapuram district, the southern part of Kerala, India, were studied using XRD, ED-XRF, TG-DTA, UV-Vis-NIR, XPS, and FTIR spectroscopy. The physicochemical parameters of the groundwater were determined and evaluated for the groundwater suitability for drinking, irrigation, and industrial purposes based on the values of total hardness, TDS, corrosivity ratio, RSC, SAR, USSL classification, saturation index, and Schoeller and Stuyfzand classification derived using “HYCH” program. Interpretation of the results shows that the groundwater is suitable for drinking, irrigation, and industrial purposes. The characterization of the profile samples reveals that the aquifer is a weathered profile with the formation of kaolinite mineral at the bottom. The results show that the hydrogeochemical processes that exist in the present study area are controlled by precipitation, not by rock–water interaction or evaporation, which suggests that the groundwater chemistry is not influenced by the aquifer minerals.