Groundwater hydrochemistry of Algerian Sahara (Southwest, Algeria) was used to assess groundwater quality to de-termine its suitability for drinking and agricultural purposes. A total of 26 groundwater samples were analysed for 14 para-meters. Standards laboratory methods were used to determine physicochemical groundwater properties. This study shows that these pH, electric conductivity, total hardness, bicarbonate, and phosphate were within WHO limits. The concentration of magnesium ranging from 30.49 to 120 mg∙dm–3 with an average value of 67.21 mg∙dm–3. 38.56% of the water points analysed have a concentration lower than the value set by the WHO at 75.00 mg∙dm–3. It also showed that 70% of the points studied have potassium concentrations that exceed World Health Organization standards. Groundwater of Algerian Sahara is low in nitrogen (NO3–) and the higher concentration may result in various health risks. The result for this study showed that the water was to be found suitable for drinking purposes except for few samples. Piper diagram indicates that groundwater in Adrar belongs to chlorinated-sulphated, sodium and magnesium facies. The groundwater samples of Adrar present high salinity and low alkalinity fall into the field of C3S1 and C3S2. Based on the RSC values, all samples had values less than 1.25 and were good for irrigation.

A field survey has been conducted for the study area using the Global Positioning System (GPS) and geological and geomorphological maps of the area. The study area is one of the important areas in Iraq characterized by scarce water resources. The purpose of the study is to determine the hydro-chemical processes and their relationship to groundwater quality carried out in the southwestern desert region of Iraq, where the region lacks extensive studies of water resources. Twenty-eight groundwater samples were collected from wells distributed between the eastern borders of Saudi Arabia and the West Bank of the Euphrates River. For the purpose of hydrogeochemical analyses, the Fetter method was used to collect and examine samples. A large part of the recharge area is located in Saudi Arabia, where the groundwater bearing aquifer represented by the Dammam formation extends to Iraq and Saudi Arabian International borders. The analysis determined the order of cations (Na+ > Ca2+ > Mg2+ > K+) and anions (Cl– > SO42– > HCO3–). High values of the variation coefficient (CV) correspond to the concentration of potassium, sodium and chloride ions (CV: 68.7, 64.7 and 64 respectively). To identify the hydrochemical water facies, the Piper diagram was used. It was found that 53% of the water samples belong to the Na-Cl type and 40% are of the Ca-Mg-Cl type, while the rest of the samples are the Ca-Cl type. To identify geochemical processes, it was found that ion exchange processes via chloroalkaline indices 1 and 2 are prevalent between Ca2+, Mg2+ in the groundwater and Na+, K+ in water bearing rocks. To learn more about the processes that led to the concentration of certain ions, such as sodium, it was found that they tend to be of silicate minerals related to surface runoff of water in recharge areas and carbonic rocks. It was also found that rock / soil-groundwater interaction and evaporation processes were the formal processes in the saturated zone and evaporation in the unsaturated zone are prevalent processes of groundwater ion concentration.