Assessment of shallow groundwater aquifer in an arid environment, Western Saudi Arabia

In arid and semi-arid regions like the Kingdom of Saudi Arabia (KSA), groundwater is considered the main source for drinking and agricultural uses due to low precipitation and limited surface water resources. The aim of this research is to evaluate the hydrogeological and hydrochemical characteristics of groundwater in Wadi Marawani basin for sustainable development. To achieve this goal, standard analytical methods have been used to determine the physicochemical parameters in sixty-four samples. Groundwater quality and controlling factors were evaluated using diagrams (Piper, Gibbs, Chadha, and HEF) and irrigation indices such as Sodium percentage (Na %), Soluble Sodium Percentage (SSP), Permeability Index (PI), Residual Sodium Bicarbonate (RSBC) and Kelly Index (KI). Also, the Support Vector Machine for Regression (SVMR) and the Multiple Linear Regression (MLR) models have been applied to predict the irrigation parameters. The results revealed that the Quaternary aquifer of unconfined condition is the main source of groundwater in Wadi Marawani basin. Depth to water measurements in sixty-two wells indicated that the groundwater flows from east to west towards the Red Sea coast. The ionic composition of the analyzed water samples showed that, Ca-HCO3, Na-Cl, mixed Ca-Mg-Cl-SO4, and Na-Ca-HCO3 are the main water types. Assessment of groundwater quality indicates that, 33%, 86%, 100%, 100% and 69% of groundwater samples are suitable for irrigation based on the calculated irrigation indices Na%, SSP, PI, RSBC and KI respectively. The SVMR model is outperformed the MLR in prediction of the irrigation indices. There was no overfitting or underfitting in the datasets used to measure, calibrate, and validate the SVMR model of four irrigation indices. Finally, this study can provide a holistic view of groundwater management for agricultural uses in the Wadi Marawani basin.