Identification of the hydrogeochemical processes and assessment of groundwater quality using Water Quality Index (WQI) in semi-arid area F'kirina eastern Algeria

Abstract

Abstract Groundwater is the primary source for human life, intended for consumption and agricultural production, particularly in the F'kirina plain, a semi-arid region in eastern Algeria. The study aims to determine the hydrogeochemical characteristics of groundwater, including (Ca2+, Mg2+, Na+, K+), CO3, HCO3−, Cl-, SO42−, NO3, PO4−, temperature, pH, electrical conductivity (EC), and total dissolved solids (TDS). The results were analyzed using XLSTAT software (2016) with Principal Component Analysis (PCA), Piper diagram, and four hydrochemical facies. Their suitability for human consumption was assessed by calculating the Water Quality Index (WQI) according to World Health Organization (WHO) standards (2011), with a WQI below 50 considered suitable for human consumption. Samples P3, P5, P6, and P15 were classified as excellent groundwater quality (WQI < 50), while samples P4, P7, P8, P9, P17, and P18 indicated good quality (50 < WQI < 100). However, 50% of the wells showed elevated levels of major elements exceeding the standards. The observed sequence of major element dominance is high quantities of Ca2 + > Mg2 + > Na + > K+, and the anions follow the order of Cl− > SO4 2 − HCO3 − > NO3 −> NO2 −. PCA results revealed two factors influencing overall hydrogeochemistry: geogenic impact attributed to the geological substrate and secondarily to prevailing geochemical (redox) conditions. Conversely, anthropogenic impact is primarily related to agricultural practices leading to nitrate enrichment and salinization. These factors contribute to groundwater quality degradation in f’kirina plain.