Hydrochemical assessment of groundwater from taluka Dahili, Thar Desert, Pakistan, for irrigation purpose using water quality indices

ABSTRACT

Groundwater is the most significant resource of fresh water for irrigation in semi-arid areas of the world. Geochemical characteristics of groundwater of taluka Dahili Thar desert was explored by analysing 23 dug well samples via irrigation indices. Physiochemical parameters and various graphical scatter diagrams were used to recognise major geochemical processes governing the groundwater quality. GIS interpolation tools were applied to demonstrate the spatial variation of groundwater quality parameters, irrigation parameters in the study area.

Statistical summary of results revealed that analysed physicochemical parameters concentration in the study area were much higher than the allowable limit of WHO with limited exceptions. Among cations Na and Mg, concentration ranges from 71 to 2470 mg/l and 40 to 344 mg/l, and anions Cl and HCO₃ values range from 103 to 4852 mg/l and 210 to 750 mg/l. Statistical data also reveals the dominant trend among the cations Na>Mg>Ca> K and in anions, Cl>HCO₃> SO₄. Gibbs and other graphical analysis reveal that dissolution of salts and minerals, ion exchange and evaporate dissolution, and weathering of rock remains the key factors affecting the study area’s water geochemistry. Piper diagram divulges that water of study area was dominantly Na-Cl. In addition to this according to Wilcox diagram and USSL diagram 82.61% locations of samples were not suitable for agriculture purposes. SAR results indicate that 71.92% for SAR, 91.30% for Na%, 95.65% for KI, and 86.96% for Magnesium hazard (MH) sample locations were unsafe for agriculture purposes. However, 86.96% for RSC and 69.57% for PI sample locations of the study area were safe for agricultural purposes.

KEYWORDS:

• Thar Desert
• IWQ
• geochemistry
• groundwater
• irrigation
• Sindh

Acknowledgments

Auther is extremely thankful to Dr Ghulam Mustafa Bajeer and Ameer Ammanullah Junejo, Sindh Coal Authority, and Sino Sindh for guidance and hospitality during fieldwork at Thar Coalfield.

Disclosure statement

No potential conflict of interest was reported by the author(s).