Assessment and mapping groundwater quality using hybrid PCA-WQI model: case of the Middle Miocene aquifer of Hajeb Layoun-Jelma basin (Central Tunisia)

Dramatic increase of population in the Hajeb Layoun City and its surrounding areas (Sbeitla, Jelma) has led to a higher consumption of water for both domestic and irrigation demands. The various uses of these resources lead to the degradation of their quality and quantity. Therefore, water quality issues and its management options need to be given greater attention in this semi-arid region. The present study is the first attempt to determine the groundwater suitability for drinking and irrigation. The Middle Miocene aquifer of Hajeb Layoun-Jelma basin), Central Tunisia, was studied using hydrochemical and statistical approaches. According to the principal component analysis approach, the source of the groundwater mineralization is manifested by both natural (lithology, quality of recharge waters, and mixing with other types of water) and the anthropogenic processes (agriculture, urban development, and increasing exploitation of water resources). Thus, the suitability for drinking purpose was tested by water quality index. However, irrigation quality was evaluated by the sodium absorption ratio, the electrical conductivity, the Wilcox diagrams, the water quality index, the soluble sodium percentage, the magnesium hazard, and the Kelly's ratio. Results indicate that only one third of the study area groundwater quality is suitable for drinking and irrigation uses. Thus, obtained results can be used as a basic document for realistic management of groundwater quality.