Hydro-Chemical Characterization of Water Resources under Climate Change Pressure in Khenchela Province, North-Eastern Algeria

Abstract

Water resources in semi-arid and arid regions are increasingly exposed to the combined pressures of climatic variability, drought, agricultural activity, urban growth, and water–rock interaction. Khenchela Province in north-eastern Algeria represents a climate-sensitive hydrogeochemical setting because it extends from relatively humid mountain and high-plain zones in the north to arid pre-Saharan areas in the south. This study evaluates the physicochemical and hydrochemical characteristics of 10 water resources sampled across Khenchela Province during June–August 2025. Field measurements included temperature, pH, electrical conductivity, and total dissolved solids, while laboratory analyses quantified Ca²⁺, Mg²⁺, Na⁺, K⁺, Cl⁻, SO₄²⁻, HCO₃⁻, and NO₃⁻. Spatial patterns were interpreted using GIS-based mapping, and hydrochemical facies were classified using Piper, Schoeller–Berkaloff, and Wilcox diagrams. Results show that water temperature ranged from 14 to 24 °C, pH from 6.75 to 7.91, EC from 702 to 3360 µS/cm, and TDS from 544 to 2579 mg/L. Northern and central sites generally showed lower mineralization, whereas southern sites exhibited brackish conditions and elevated Ca²⁺, Na⁺, Cl⁻, SO₄²⁻, and NO₃⁻ concentrations. The dominant hydrochemical facies were Ca–Mg–HCO₃, mixed Ca–Mg–Cl/Ca–Mg–SO₄, and Ca–Cl types, reflecting spatially variable carbonate dissolution, evaporitic influence, and longer water–rock interaction. Wilcox classification indicated that most samples were suitable for irrigation, but southern waters showed salinity and sodicity constraints requiring careful soil and irrigation management. The findings indicate that water quality in Khenchela Province is controlled by both natural hydrogeochemical processes and environmental stress associated with aridity. Although the dataset does not allow direct long-term attribution to climate change, the observed southward increase in salinity and mineralization highlights the vulnerability of regional water resources under conditions of warming, irregular rainfall, and reduced dilution. The study provides a valuable baseline for hydrochemical monitoring and supports the need for seasonal sampling, nitrate surveillance, salinity management, and integrated climate–water-resource planning in north-eastern Algeria.