Hydrogeochemical investigation of the groundwater quality controlling processes involved in north-western Bangladesh using statistical approaches

Groundwater is the principal source of drinking water for the residents of the Bengal Delta Plain. However, its quality has reportedly been declining due to various anthropogenic and geogenic activities. Therefore, it is crucial to investigate the current status of groundwater quality for sustainable resource management. This study aims to assess the current groundwater chemistry and evaluate the drinking water quality in the northwestern region of Bangladesh within the Bengal Delta, using multivariate statistical methods and water quality index (WQI) calculation. Data on various water quality parameters—fluoride, calcium, chloride, potassium, sodium, ammonium, nitrate, magnesium, pH, electrical conductivity (EC), water hardness, TOC, sulfate, carbonate, bicarbonate, trace and heavy metal profiles—were obtained from 128 sites across five sub-districts (also known as Upazila) in north-western Bangladesh. The results indicate that majority of the parameters met the standards defined by the WHO, except for NO3− in Baliadangi Upazila, where the study identified the underlying cause of this NO3− contamination. The WQI classified the 120 samples as follows: 55.00% were excellent, 34.17% were good, 10.00% were poor, and 0.83% were unfit for consumption. The groundwater samples in the region were free from heavy metals and contained permissible amounts of trace metals. The cluster analysis (CA) and principal component analysis (PCA) identified diverse ions in various Upazilas as the influencing factors in water chemistry, primarily originating from either carbonate or silicate weathering processes. Overall, this study provides valuable insights into groundwater chemistry and quality, serving as a resource for those concerned with sustainable groundwater management.