Groundwater quality assessment for different uses using various water quality indices in semi-arid region of central Tunisia

The Hajeb Layoun-Jelma basin, located in the central Tunisia, is the principal source of water supply for Sidi Bouzid and Sfax region. The over-abstraction from this groundwater, since 1970, and the intensive agriculture activities led to the degradation of the water quantity and quality. The quality evaluation for this groundwater is very important tool for sustainable development and decision for water management. A total of 28 groundwater samples, from shallow, springs, and deep aquifers, were collected, storage and analyzed to evaluate its quality suitability for domestic and agriculture purposes using geographic information system and geochemical methods. For the both aquifers, the abundance of cations: Na > Mg > Ca > K, and of anions in the order: Cl > HCO3 > SO4. The dominant hydrochemical facies, for the shallow aquifer and springs, are Na-Cl and Ca-Mg-Cl; for the deep aquifer, the geochemical facies are Na-Cl, Ca-Mg-Cl, and Ca-Cl. The comparison of the major parameters and the chemical data with the World Health Organization standards and the national standards indicate that this groundwater is suitable for drinking, except in some samples, with high salinity concentrations. The water quality was assessed, for drinking uses, using "water quality index," "entropy," and "improved water quality index." The results mentioned that the improved water quality index is the best method which indicated that the poor water quality coincide with the Na-Cl water type. The entropy method and the water quality index present the optimistic methods. The irrigation suitability assessment was made using various parameters (SAR, TH, % Na, PI, MH, KR, EC). The results revealed that the majority of samples in Hajeb Layoun-Jelma basin are not appropriate for irrigation uses

Water quality assessment of the Triassic aquifer, SE Tunisia, for drinking water supply

The Triassic aquifer is located in southereastern Tunisia, in the Medenine region, and being part of Jeffara's multilayer aquifer system. The aquifer is currently overexploited with an exploitation rate of 163%, which led to a generalized drop in the piezometric level in the order of 20 cm/year. This study applied conventional techniques such as hydrochemical compositions, multivariate statistical methods and Geographical Information Systems (GIS). To better identify the processes controlling the hydrogeochemical evolution of groundwater quality of Triassic aquifer and its suitability for drinking uses, 14 well water samples from the Triassic aquifer were analysed for physical character and chemical composition. In the groundwater, the respective order of cation and anion concentration was Na>Ca>Mg>K and SO4>Cl>HCO3. The chemical data of water samples from the study area presented by plotting on a Piper diagram reveals the predominance of two hydrochemical types: a Na-Ca-Mg-SO4 facies and a Na-Ca-Mg-Cl-SO4 facies. Analytical results demonstrate that the chemical composition of groundwater in Triassic aquifer is strongly influenced by residence time and flow path. Water quality deteriorates going from southwest to northeast across the region, coincident with the appearance a clay layer limiting the infiltration of rainwater. The majority of ions are above the maximum desirable limits recommended for drinking water by WHO guidelines and Tunisian Standards (NT.09.14). Based on the Water Quality Index (WQI), 36% of water samples of the Triassic aquifer are classified as "poor water" and they cannot be used for drinking purposes without prior treatment

Suitability evaluation of groundwater from the Skhira coastal aquifer of east-central Tunisia for use as drinking water

The Skhira coastal aquifer is located in east central Tunisia. It is already affected by the intrusion of saline water phenomena. This study evaluated the suitability of aquifer groundwater various using data on chemical and physical data from 31 wells for the decade from 2000-10. Salinity increases in the direction of flow and exceeds 10 g/L in the northeast region. Groundwater composition is controlled primarily by the concentrations of sodium, chlorides and sulphates. The majority of the groundwater samples are not potable

Groundwater vulnerability based on GIS approach: Case study of Zeuss-Koutine aquifer, South-Eastern Tunisia

La cartografía de la vulnerabilidad del agua subterránea se utiliza como herramienta de modelado de contaminación y para proteger los recursos hídricos. El acuífero Zeuss-Koutin, que constituye una fuente primordial de agua potable en el sur este de Tunez, esta sometido a una explotación intensiva y amenazado de contaminación debido esencialmente a la zona industrial de Koutine. El agua subterránea circula a través de piedra calcarea fisurada y karstificada. La vulnerabilidad del acuífero se ha evaluado en los acuiferos Zeuss-Koutine utilizando el método SINTACS. Los distintos parámetros del modelo se obtuvieron de distintes fuentes y se hicieron mapas temáticos utilizando ArcGis. A cada parámetro SINTACS se le asigno un peso y una clasificación basados en una amplia gama de información del parámetro. El peso de cada parámetro depende del impacto de la contaminación potencial. El análisis del mapa de vulnerabilidad a la contaminación muestra que la parte sud-este del acuífero y los lechos Wadis son más susceptibles a la contaminación. Las concentraciones de nitratos medidas en dos campañas de muestreo realizadas en temporadas altas y secas en agua son coherentes con los resultados del modelo SINTACS. doi: https://doi.org/10.22201/igeof.00167169p.2017.56.2.176