Assessment of the hydrochemical characteristics of water and aquifer hydraulic properties is important for groundwater planning and management in the study area. It is not only the basic need for human existence but also a vital input for all development activities. The present hydro-geochemical study of groundwater samples from the Suri I and II blocks of Birbhum district, West Bengal (23.76°–23.99°N; 87.42°–87.64°E) was carried out to assess their suitability for agricultural, domestic and drinking purposes. For this study, samples were collected from 26 locations during the post-monsoon and pre-monsoon sessions spanning over 2012 and 2013. Groundwater samples were analyzed for their physical and chemical properties using standard laboratory methods.
Physical and chemical parameters of groundwater such as pH, electrical conductivity, total dissolved solids, Na, K, Ca, Mg, Fe, Cl, HCO3, SO4 and F were determined. Various water quality indices like SAR, SSP, PI, RSC, MAR and KR have been calculated for each water sample to identify the irrigational suitability standard. According to most of these parameters, the groundwater has been found to be well to moderately suitable for irrigation. In the post-monsoon session exceptionally high RSC values for around 80% samples indicate an alkaline hazard to the soil. The ion balance histogram for post-monsoon indicates undesirable ion balance values according to fresh water standards whereas in pre-monsoon, the samples show good ion balance in water. For determination of the drinking suitability standard of groundwater, three parameters have been considered – total hardness (TH), Piper’s trilinear diagram and water quality index study. Groundwater of the present study area has been found to be moderately-hard to hard during both sampling sessions and hence poses no health risk which could arise due to excess consumption of calcium or magnesium. Hydrogeochemical facies in the form of Piper’s trilinear diagram plot which helps in identification of the water ‘type’ which can render a particular taste or odour to water, indicates that groundwater in the study area is majorly of CaMgHCO3 and NaHCO3 type (fresh type) during both post-monsoon and pre-monsoon sessions barring a couple of samples which are of CaMgSO4/CaMgClSO4 type in pre-monsoon. Water quality index study reveals that close to 90% of the water samples are suitable for drinking during post-monsoon compared to pre-monsoon during which period only 60% of water samples fall under the suitable drinking water category.
Gibbs’ diagrams, which help in identification of natural processes controlling hydrogeochemistry of groundwater indicates that for both post-monsoon and pre-monsoon sessions, the overall hydrogeochemistry of the study area is dominated by rock–water interaction processes.