GIS-based spatial assessment of water quality, soil, and plant: a case study of Darawat Dam Sindh, Pakistan

Abstract

This study applied integrated statistical approaches, including GIS mapping and the water quality index (WQI), to assess the quality of water, soil, and plant samples which collected from Darawat Dam, Sindh, Pakistan. The samples were analyzed for physicochemical parameters and metal analyses. Results of cations in water samples were in the range Na⁺ 26.74 to 39.67 mg/L, K⁺ 0.92 to 2.89 mg/L, Ca²⁺ 28.67 to 39.45, and Mg²⁺ 19.67 to 34.43 mg/L. The values of Cl⁻ in water samples were 44.54 to 61.26 mg/L, sulfate 27.11 to 46.45 mg/L, and bicarbonate (HCO₃⁻) 100 to 135 mg/L. The results of major and trace elements in soil samples were varied for Na⁺ 1259–1781 mg/kg, K⁺ 306–498 mg/kg, Ca²⁺ 689–1093 mg/kg, Mg²⁺ 357–795 mg/kg, Zn 194–235 mg/kg, Fe 124–242 mg/kg, Cu 25.34–33.56 mg/kg, Co 19.45–27.32 mg/kg, Mn 97.83–131 mg/kg, Ni 39.65–52.44 mg/kg, Cr 69.64–83.65 mg/kg, Cd 3.98–8.66 mg/kg, and Pb 5.34–9.62 mg/kg respectively. The major and trace elements in plant samples were varied from Na⁺ 3456 to 5016 mg/kg, K⁺ 1197 to 1654 mg/kg, Ca²⁺ 2367 to 2892 mg/kg, Mg²⁺ 1429 to 1686 mg/kg, Zn 132 to 155 mg/kg, Fe 255 to 354 mg/kg, Cu 19.54 to 28.56 mg/kg, Co 11.64 to 14.65 mg/kg, Mn 23.54 to 34.78 mg/kg, Ni 8.44 to 11.03 mg/kg, Cr 6.34 to 9.55 mg/kg, Cd 0.43 to 0.93 mg/kg, and Pb 4.33 to 6.59 mg/kg. The GIS maps were drawn for TDS, Cl⁻, Na⁺, heavy metals Cr, Cd, and WQI and these graphs showed that most of the water samples of Darawat Dam is good for human consumption. The results of electrical conductivity (EC) and total dissolved salts (TDS) of water samples were found to be from 648 to 753 µS/cm and 414 to 482 mg/L. The Darawat Dam water samples were good for drinking as well as irrigation based on the results of water quality parameters. The WQI specified that 100% of samples were excellent to good for water quality for drinking. The 100% samples were also excellent for crops. The scatter diagram disclosed that weathering and ion exchange were chief processes. The Gibbs diagram revealed that all samples showed rock dominance which confirmed the dissolution of rock as the main source for the water quality of the Dam. The hydrogeochemical facies (Piper diagram) showed that sample points were gathered in the center of the diagram which indicated mixed type water with no particular parameter effluents the water quality.