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+) - (HCO3- + SO42-) versus (Na+ + K+) - Cl- (meq/L) inferred the presence of ion exchange process causing adsorption of Ca2+ and release of Na+. The Ca2+ - Mg2+ - Cl-, Na+ - HCO3-, and Ca2+ - Mg2+ - HCO3- 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.