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 Ca and Na are observed as the dominant cations from pre- to post-monsoon season. On the other hand, HCO and Cl are observed dominant anions during pre-monsoon and monsoon seasons, whereas HCO and SO 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 HCO is noticed to be mainly originated from carbonate/calcareous minerals during monsoon and post-monsoon, but through silicate minerals during pre-monsoon.  The SO 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 NO, NH, F, and Br are mainly a result of anthropogenic activities. The alkaline earth metals are found to surpass over alkali metals, whereas weak acid (HCO) exceed to strong acid (SO). The Piper diagram has shown Ca-HCO 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.