Comprehensive suitability and hydrogeochemical characteristics of groundwater in Khanaqin, Iraq

Groundwater quality is essential for the sustainable growth of society, economy, and agriculture; however, anthropogenic activities pose a significant concern. The objectives of this study are to evaluate the variety in hydrochemical characteristics and groundwater quality of the Khanaqin region, Diyala Governorate, Iraq, for twenty-four borehole samples analyzed is the main water supply. Physicochemical parameters, like cation-anion compositions, electrical conductivity, total dissolved solids, and pH, are utilized to evaluate the groundwater suitability for drinking and irrigation purposes through comparison with standard limitations. Whereas multi-indices, followed by the irrigation and drinking water quality index, were used to assess the suitability, integrated with GIS to create a spatial variation map. Based on the findings, most wells were suitable for drinking and irrigation as a result of their acceptable ionic concentrations. Spatial analysis demonstrates that pollution originates from highly populated northern areas and gradually decreases southward, correlating with an increased presence of water canals. TDS values ranged (295-5300) mg/L, with the majority of the study area having a freshwater class with a TDS value lower than 1000 mg/L. Besides, 84% of the wells can be categorized as having very hard water. Hydrochemistry facies show that most of the samples were classified as mixed water facies, 42% as Na–Cl, and 12% of the samples were classified as Ca–Mg–SO₄ facies. Furthermore, the cation order was Na > Ca > Mg > K, while the anion order was SO₄> Cl > HCO₃> NO₃. Na values ranged (30-428) mg/L, Ca from 16 to 260 mg/L, and sulfate from 12 to 1010 mg/L. According to the computed DWQI, 84% of the wells were classified as good and excellent water types. On the other hand, the IWQI of irrigation suitability depends on seven indices: SAR, PS, Na%, SSP, KR, PI, and MH. The results specify 79.42% of the wells were classified as high suitability for irrigation. Anthropogenic activities and geogenic processes primarily control groundwater chemistry in the Khanaqin area.