Hydrochemistry and water quality of Rewalsar Lake of Lesser Himalaya, Himachal Pradesh, India

The present research is to study hydrochemistry and water quality of Rewalsar Lake during pre-monsoon, monsoon, and post-monsoon seasons. The Ca2+ and Na+ are observed as the dominant cations from pre- to post-monsoon season. On the other hand, HCO3− and Cl− are observed dominant anions during pre-monsoon and monsoon seasons, whereas HCO3− and SO42− during post-monsoon season. The comparison of alkaline earth metals with alkali metals and total cations (Tz+) has specified that the carbonate weathering is the dominant source of major ions in the water of lake.  The HCO3− is noticed to be mainly originated from carbonate/calcareous minerals during monsoon and post-monsoon, but through silicate minerals during pre-monsoon.  The SO42− in Rewalsar Lake is produced by the dissolution of calcite and dolomite etc. The alkali metals and Cl− in the lake can be attributed to the silicate weathering as well as halite dissolution and anthropogenic activities. Certain other parameters like NO3−, NH4+, F−, and Br− are mainly a result of anthropogenic activities. The alkaline earth metals are found to surpass over alkali metals, whereas weak acid (HCO3−) exceed to strong acid (SO42−). The Piper diagram has shown Ca2+–HCO3− type of water during all the seasons. The water quality index has indicated that the water quality of the lake is unsuitable for drinking from pre- to post-monsoon. Several parameters like salinity index, sodium adsorption ratio, sodium percent, residual sodium carbonate, magnesium hazard etc. have revealed the water of Rewalsar Lake as suitable for irrigation.