Geochemical Analysis of Soil Facies and Groundwater Quality in the Valley of Oued Righ in Southern Algeria, with a Specific Focus on the Terminal Complex

Abstract

Groundwater plays a crucial role in arid regions like the Oued Righ valley, where high evaporation rates make it the primary water resource. This study aims to evaluate the quality of the Complex Terminal groundwater in the Oued Righ region. Various analyses, including temperature, electrical conductivity (E.C), pH, total dissolved solids (TDS), and ion concentrations (such as Ca²⁺, Mg²⁺, Cl^-, HCO₃^-, SO₄^-2, NO₃^-, NO₂^-, PO₄^-3, Iron, and Fluor), were conducted to determine the chemical water facies, their interactions, and suitability for human consumption and agricultural use. The results reveal that the Complex Terminal aquifer exhibits a neutral pH (7.33 ± 0,2) and moderate mineralization (TDS = 2395.25 ± 771.18 mg/l). However, some parameters indicate pollution and undesirability, such as nitrite, iron, and fluorine, exceeding the World Health Organization's standards. On the other hand, ions like nitrate and orthophosphate meet the recommended standards. The groundwater in the Complex Terminal aquifer undergoes water-rock interactions, forming impermeable geochemical facies primarily composed of clay, gypsum, and anhydrite (Bel and Demargne., 1966). This mineralization is attributed to the correlation between calcium and sulfate ions, originating from the alteration of anhydrite, a calcium sulfate compound. Haut du formulaire

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This work focuses on investigating the relationship between irrigation water and soil salinity through the direct measurement of neutral salts in the soil's imbibition water (Omran and Marwa, 2015). The accumulation of neutral salts in soils is influenced by the intensity of irrigation, and their toxicity can harm plants while reducing water availability. High concentrations of Cl^- can particularly affect plant tissues and leaves. The hydrogeochemical properties of the study area are primarily influenced by the interaction between water and rock, as well as cation exchange (Cornet, 1964). Soil acidity, measured by pH, was found to be moderately acidic in most samples (ranging from 7.4 to 7.8), except for the southern part of the study area, which exhibited alkalinity in the Goug and Baldet Omar areas. The Oued Righ region is characterized by the accumulation of NaCl, which can be attributed to the presence of chloride ions and sodium cations, showing strong correlations of 0.95 and 0.94, respectively. These factors directly impact the electrical conductivity and the presence of other salts, thus influencing their variation.