Hydrogeochemical assessment of groundwater for agricultural suitability in the Ksour Mountains, Algeria

Abstract

The Ain-Sefra region, located in south-western Algeria has an arid climate and the groundwater is a vital resource for irrigation and domestic purposes. In the absence of other resources, conventional or otherwise, groundwater remains the driving force behind the region's development. Recognizing the importance of groundwater in agriculture, this research utilized a combination of water quality indices and GIS techniques to map and evaluate the suitability of groundwater for agricultural purposes. Several physicochemical variables, such as major elements, electrical conductivity (EC), potential hydrogen (pH), temperature (T°), total dissolved solids (TDS) were measured from 43 water samples. Hydrochemical groundwater facies were Ca-Mg-SO₄-Cl, Ca-Cl, Ca-Mg-HCO₃ and Na-Cl, revealing processes of evaporation, reverse ion exchange and rock-water interaction. Additionally, the results show that the groundwater system is oversaturated with aragonite, calcite, dolomite, anhydrite, and gypsum, while halite is estimated to be undersaturated. A range of indices, such as electrical conductivity (EC), salinity, sodium absorption rate (SAR), sodium percentage (% Na), residual sodium carbonate (RSC), magnesium hazard (MH), Kelly ratio (KR), and permeability index (PI), were used to evaluate the groundwater suitability for irrigation. Although the groundwater is found to be suitable for agricultural use, salinity control measures are essential. Spatial variation maps of water quality indices reveal that groundwater from downstream part is highly mineralized, while low mineralized water observed in the western and southwestern parts.