Groundwater geochemical facie: implications of rock-water interaction at the Chamba city (HP), northwest Himalaya, India

The present study describes geochemical facie and implications of rock-water interaction at the groundwater of Chamba city. The influence of rock dominance at the groundwater may be due to its flow and longtime rock-water interaction, whereas atmospheric precipitation dominance owing to high recharge and continuous outflow of groundwater that cause a short time interaction. The comparison among Ca2+ + Mg2+ versus Na+ + K+ and total cations indicated carbonate weathering as a main ionic source relative to silicate weathering, due to rich lithology and higher dissolution capacity of carbonate minerals. The chloro-alkaline indices (CAI-1 and CAI-2) and scatter plot of (Ca2+ + Mg2+) – (HCO3ˉ + SO42ˉ) versus (Na+ + K+) – Clˉ (meq/L) inferred the presence of ion exchange process causing adsorption of Ca2+ and release of Na+. The Ca2+ – Mg2+ – Clˉ, Na+ – HCO3ˉ, and Ca2+ – Mg2+ – HCO3ˉ types of groundwater suggested permanent and temporary hardness in the region. The Ca2+ and Na+ are observed as the dominant cations whereas HCO3– and SO42– as the dominant anions. The parameters like NH4+, NO3–, F–, and Br– are generated from different natural sources. The groundwater is found to be suitable for drinking purposes based on water quality index (14.24–61.13) and the Bureau of Indian Standards (BIS 2012) prescribed limit. The influence of carbonate minerals dissolution over TDS and salinity at groundwater of the city is also observed. The rock-water interaction confirmed mixing pattern of carbonate, silicate, and evaporites in the groundwater of the Chamba city.