Masum Howlader

Satkhira Municipality is located in the extreme South-Western coastal region of Bangladesh. This area exhibits complex hydro-geochemical characteristics along with the increasing tendency of soil and water salinity which created a need of groundwater quality assurance. The objectives of the study were to identify the composition of groundwater followed by attempts to investigate spatial distribution pattern of groundwater quality. This was done to identify places with the availability of best quality of drinking water. This was achieved by combining the geographical information system, statistical analysis and diagrammatic presentation. A total of 100 deep tube well (450 to 600 feet) water samples were collected during monsoon and dry season in 2018 and were analyzed for hydro-geochemical parameters. The groundwater was neutral to alkaline (pH 7.01 to 8.66) in nature. Total dissolved solids ranged from 132.7 to 1436.0 mg L-1 which gradually increased from North to South direction. Sodium was the most dominant cation with mean value of 48.28 (±27.48) mg L-1 in monsoon and 105.35 (±66.73) mg L-1 in dry season. On the contrary, Cl- ion was the dominant anion with mean value of 546.99 (±34.07) in monsoon and 424.68 (±398.59) mg L-1 in dry season. The high loading (>0.6) in principal component analysis indicated that the major ions originated from mineralization of rocks and soils, which was supported by Gibbs diagram. Silicate weathering supposed to be the responsible factor for releasing Na+ ion, while Ca2+ and Mg2+ ion in groundwater came from both silicate and carbonate weathering. Three distinct types of groundwater facies e.g. the mixed NaCaCl, NaCaHCO3 and NaCl were active along the study area, indicating that the underground cation exchange process. Our study will be helpful for the decision makers for planning a better operation and maintenance of groundwater resources.