A study on groundwater hydrochemistry in Khatra Block, Bankura district, West Bengal

Abstract

A study was conducted to detect the hydrochemistry of groundwater in Khatra Block,Bankura district, West Bengal. For this, nineteen water samples from borewells during postmonsoon and premonsoon sessions each were collected. Analyses of these water samples were done to evaluate their hydrochemistry and usability for domestic and agricultural uses. Measurement of some parameters which include pH, TDS, and EC has been done in situ sample location points itself. For determining other parameters like cations (Ca2+, Mg2+, Fe2+, Na+, K+) and anions (Cl−, HCO3−, SO42−, F−), samples were brought to the laboratory. For determining irrigation suitability of collected groundwater samples, parameters such as sodium adsorption ratio (SAR), soluble sodium percentage (SSP), residual sodium carbonate (RSC), magnesium adsorption ratio (MAR), Kelly’s ratio (KR), permeability index (PI) and corrosivity ratio (CR)were calculated. The waters are found to belong to low salinity and sodium types when marked in the US Salinity Laboratory (1954) diagram and suggest good for agricultural uses. The hydrochemistry of the investigated area is normally good but varies from very hard to hard. In few localities of the investigated area, total hardness is identified as high, which suggest not to use the water for drinking purpose. In such places, the groundwater may be contaminated by interaction between rock and water along with agricultural drain out. The Piper plot shows marked domination of Ca2+–Na+–SO42−, mixed Ca2+–Mg2+–Na+–HCO3− types. To determine the suitability of these groundwater samples for domestic purposes, Water Quality Index (WQI), Gibb’s ratio for both cations and anions, and Chloro-Alkaline Indices (CAI) have been calculated along with plotting in Chadha’s and Schoeller diagrams. It also indicates the preponderance of alkaline earth over alkalis and weak acids over strong acids. For utilizing the groundwater in domestic purposes, index of water quality was also determined. Water Quality Index values varied from 74.74 to 209.4 in postmonsoon, and 70 to 205 in premonsoon period which suggest the water good enough to use for domestic purposes.