Evaluation of the physico-chemical quality of groundwater in arid areas: case study (watershed of the Oued Bechar) in Bechar- Kenadsa Region

摘要

This work is based on the characterization of the physico-chemical parameters in the groundwater of the Bechar-Kenadsa region in southwest Algeria. To achieve this goal, we have collected a database of a water sampling survey that has been done by the National Hydric Resources Agency (ANRH) of the different water points located in the study area according to recognized standards for the collection and analysis protocols of water samples. We extracted the pH, EC, TDS, Ca+2, Mg+2, Na+, K+, Cl-, HCO3-, SO4 and NO3- parameters, we used these physical and hydro chemical characteristics to evaluate the parameters of the sodium content (Na %), Kelly's rate and permeability index. The results showed that just small portion of the groundwater was drinkable. We also used diagrams like Piper's to distinguish that the main water quality is of the Mg-Cl-SO4 class. The Durov's diagram helped us to know that most of this water is concentrated in the area, of magnesium-dominance, characterized by two main classes of water (Mg-Cl-SO4 and Mg-Ca-Cl-SO4). The Gibbs diagram was used to assess the mechanisms controlling the chemistry of water. We noticed that the quality of the water was influenced by the precipitation process in the first row. According to the Wilcox diagram, it was noted that most of groundwater in the study area is characterized by high salinity under three main classes (C4-S1, C4-S2 and C4-S3). We can than conclude that the groundwater in the study area is of poor quality for drinking and irrigation and requires serious treatment to be exploited.