Hydro-geochemistry and simulation for the sub subsurface environment of groundwater of Shahdara, Pakistan
摘要
Groundwater, a vital source essential for life, is under threat due to human activities, facing both contamination and rapid depletion. The current study underscores the importance of understanding the complex interplay between human activities, lithological variations, and their impact on groundwater quality. The research focuses on Shahdra Town in northern Lahore, Pakistan, for modelling and simulation to assess anticipated groundwater levels and quality. A total of 08 tube wells were selected for study. The borehole data of selected tube wells were used to visualize 2D and 3D fence models (Rockworks, Ver 16 ®) for the variation in lithology. Based on the similarity in the lithology, the tube wells are divided into four groups. The groundwater samples from all locations were analyzed for 20 parameters and compared against the Punjab Environmental Quality standards. The results showed a high total dissolved solids concentration (1080 mg/L), alkalinity (270 mg/ L), and the concentrations of metals (Pb, As, and Co) were very high as per WHO guidelines. The concentration of parameters was used to draw Piper diagrams, Stiff diagrams, and Scholler diagrams, which illustrated the dominance of anion facies (carbonate and bicarbonate) and cation facies (Na and K). The metal concentrations were plotted on a GIS map (ArcGIS Ver 10.4 ®), which showed that the locations near the river Ravi have high metal concentrations due to the discharging of groundwater. To study the depletion rate of groundwater, a calibrated simulation model (MODFLOW 2011.1 ®) was used. It was found that if the current conditions prevailed, then the groundwater drawdown would be 0.52 m/decade. The additional installation of a tubewell will enhance the drawdown up to 0.82 m/decade. The government should strictly implement the water policy, which is approved but yet to be enforced.