Microbial contamination effects on the hydrochemical parameter in a Thettiyar watershed, Kerala, India, using GIS

The present study has been carried out to assess the quality of groundwater and surface water resources of Thettiyar watershed, Kerala, India. Sixty-six water samples were collected during pre-monsoon (April, 2019) and monsoon (July, 2019) season, and analyzed for pH, electrical conductivity (EC), total dissolved solids (TDS), total hardness and major cations and anions and microbiological parameters as well. According to the piper diagram's plot, Ca and Mg dominate over Na among the cations, and Cl is the most prevalent anion in groundwater throughout both the studied seasons. The hydrochemical analysis of water samples revealed that all the parameters are within the permissible limit except for pH. For microbiological analysis, the samples were tested for total coliform and fecal coliform. Most of the groundwater samples collected have higher total coliform and fecal coliform (E. coli) content than the recommended count by BIS (2012). The pre-monsoon surface water samples owned a maximum number of 3700 cfu/100 ml (TNTC-too numerous to count) of total coliform and 1400 cfu/100 ml (TNTC) of fecal coliform. In monsoon, the number of total coliform and fecal coliform has increased to 3800 cfu/100 ml and 1900 cfu/100 ml respectively. E. coli and total coliform are effectively correlated with each other in both seasons, in accordance with the statistical study. Domestic, sewage dump, and other household wastes are the main sources of bacterial contamination in the study area, which in turn nourishes contaminant organisms. According to the results, the government or municipality should implement an appropriate system for managing solid waste and should take all necessary measures to clean up the study area.