Assessment of the hydro-geochemical characteristics of a Tropical River catchment in the southern Western Ghats, India

The understanding of small tropical streams that drain in mountain ranges is still limited. Thus, the hydro-geochemical characteristics of a tropical river, Chit-Ar, in the Vamanapuram River, draining through the charnockite and khondalite rocky terrain of southern Western Ghats, India, are monitored. The lack of variation in the physicochemical parameters of the Chit-Ar River Basin (CRB) spatially and temporally points out the fewer human interventions and climatic irregularities in the study area. Thus the major cation and anion obey the order of abundance as Na + > K + > Ca 2+ > Mg 2+ and HCO 3 – > Cl – > SO 4 2– . The Piper diagram and Gibbs plot indicate that precipitation is the predominant source of CRB, and there is no dominant type of water composition. The scatter plot of major cations and anions and the weathering diagram demonstrate that silicate weathering determines the hydrochemistry in non-monsoon seasons. Statistical analysis, like principal component analysis (PCA), shows a strong correlation between the parameters and confirms the intense silicate weathering in the terrain. CRB water quality was assessed as falling under the ‘excellent’ category. Overall, this study proves the pristine hydrochemical nature of the tropical mountainous river system concerning the increased human interferences and extreme climatic events. Research highlights In Chit-Ar River, dominant cation facies are principally mixed type, i.e., Ca–Na–HCO 3 , and anion facies are HCO 3 –Cl type. The primary source of the Na + ion is not chloride, which proves the less anthropogenic activity and atmospheric deposition. The origins of the major ions produced by silicate weathering, without any spatial and temporal variation. According to PCA, TDS and major ions (Na + , K + , Ca 2+ , Mg 2+ , HCO 3 – , SO 4 2– ) are shows strong correlation and intercorrelations. The chemical and biological drinking water quality falls in the ‘excellent’ category, according to WQI.