An Environmental Study to Determine The Groundwater Quality Index for Agricultural Purposes in Areas Near The Bahr Al-Najaf Depression Using GIS

Abstract

Abstract In this research, the quality of groundwater was studied for fifty wells distributed in areas near the Bahr al-Najaf depression. Where a large discrepancy was observed in the readings and concentrations of the thirteen variables that were identified, they included both the acid function pH and their ranged between (7.11 - 7.29) and the electrical conductivity EC whose values in the number of wells measured were between (2351 - 8901 μS/cm) and the total dissolved salts TDS were between (1520 to 5773 mg/L). In this study, the concentrations of positive ions were also measured, including calcium, and their values ranged between (155 to 594 mg/L), sodium (235 to 895 mg/L), potassium (2 - 101 mg/L), and magnesium (60 to 337 mg/L). Negative ions represented by sulfates SO4 2- were also studied, and their concentrations ranged between (517 to 1919 mg/L), chlorides Cl− (293 to 1243 mg/L), and nitrates NO3 − (0.3 - 1.8 mg/L). The concentrations of heavy metals in the water of these wells were also studied, and their values included lead ions (0.00 - 0.0183 mg/L), cadmium (0.00 - 0.0038 mg/L), and manganese (0.2464 - 1.1628 mg/L). Then the water quality index WQI for these wells was determined, and a large discrepancy in the results was also noted after using the geographic information system GIS when drawing maps and distributing the results on them.