Geostatistical and Geospatial Assessment of Groundwater Quality from Saq Aquifer in Tabuk Area of Saudi Arabia

Abstract This study investigates the hydrochemical properties and assesses groundwater quality for drinking and irrigation purposes of groundwater from the Saq aquifer in the Tabuk region of Saudi Arabia, a critical water source for agriculture and nearby communities. Various water quality indices, including the Water Quality Index (WQI), electrical conductivity (EC), sodium percentage (%Na), sodium adsorption ratio (SAR), permeability index (PI), magnesium hazard (MH), potential salinity (PS), and Kelley’s ratio (KR), were employed to evaluate groundwater quality. The Piper plot analysis reveals that there is a mixture of groundwater types in the region, with the majority of groundwater samples falling into the mixed (Ca+Mg) -(SO4+Cl) category. The calculated WQI results indicate that 93% of the samples are rated as excellent to good for irrigation. In terms of electrical conductivity (EC), 52% of the samples are considered good, and the remaining 48% are classified as permissible. In the SAR classification, all groundwater samples in the study region exhibit low salinity and low sodium hazard levels. According to the PI, most of the samples are moderately suitable for irrigation. The calculated PS values show that 40% of the samples are excellent for irrigation, 48% are considered good, and the remaining 12% may not be appropriate for irrigation purposes. The MH values indicate that approximately 10% of the water samples are suitable for irrigation, whereas the remaining portion may require further treatment before use. Factor analysis reveals three significant factors explaining 75.29% of the total variance. The Gibbs scatter diagram revealed that groundwater chemistry in the area is controlled by rock chemical weathering and evaporation processes. The integration of hydrochemical analysis, Water Quality Index (WQI), Geographic Information Systems (GIS), and factor analysis proves valuable for understanding the factors influencing groundwater chemistry. This holistic approach can provide valuable insights to assist planners in the effective management of groundwater quality.