The main objective of this study is to assess the groundwater quality beneath urban settlements along banks of Malir River in Karachi, which is major drainage of Karachi to transport domestic and industrial wastewater into the Arabian Sea. Due to discharging untreated domestic sewage and industrial wastewater, it has become highly polluted with undesired contents which may also cause an adverse impact on the quality of shallow groundwater along the banks. For this purpose, 20 and 24 groundwater samples each from Right Bank (RB) and Left Bank (LB) of Malir River were collected boring wells at various depths (12-300ft). The samples were analysed to determine physical (pH, ORP, total dissolve solid (TDS), electrical conductivity (EC), hardness, alkalinity, salinity, specific gravity, temperature, taste, colour and odour) and chemical parameters (Ca2+, Mg2+, Na+, K+, Cl-, SO42-, NO3-, HCO3- and F-). Besides, Iron (as minor element) and faecal coliforms were estimated. Data revealed that groundwater salinity is very high along both banks of Malir River which varied in the order of Right bank (mean TDS=8983 mg/L) > Left bank (mean TDS=3163 mg/L). The groundwater from both banks was found contaminated, where the RB was found more polluted as compared to LB of Malir River. Microbiological analysis revealed that 50 and 60% samples each from RB and LB have pathogenic bacterial occurrence, which suggests that sewage infiltration is common in groundwater of study area. Principal Component Analysis (PCA) revealed five significant factors, which indicate that the both natural and anthropogenic factors are responsible to alter the groundwater characteristics of study area. It is concluded that the groundwater along Malir River on both banks is unfit for drinking purpose, and the situation is worst towards the right bank.
Groundwater, Malir River, River bank, Drinking quality, Contamination