Groundwater quality assessment in semi-arid regions using integrated approaches: the case of Grombalia aquifer (NE Tunisia) (original) (raw)
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Groundwater is the most precious and valuable natural source of water in the southeast of Tunisia. The aim of this study is to find an adequate combination of methods for a qualitative description of geochemical processes into the Zeuss-Koutine, a Triassic and Miocene groundwater system, the unique source of water for this region of the Mediterranean (Medenine, Jerba, Zarzis and Jorf cities).Conventional classification techniques, statistical analyses and kriging methods were used to identify mineral processes distribution. This study finds that water chemistry is mainly dominated by dissolution/precipitation of minerals (calcite, dolomite, aragonite, anhydrite, gypsum and halite). Results obtained from principal component analyses (PCA) demonstrate that the variable responsible for water quality are largely related to soluble salts species (Na + , Cl-, Ca 2+ , Mg 2+ and SO 4 2-). On the basis of the hierarchical cluster analysis (HCA), three groundwater clusters have been distinguished : cluster 1 is low TDS (<1000 mg L-1) Ca 2+ = Mg 2+-Na +-SO 4 2waters which degrades into predominantly Na +-Ca 2+-Cl-SO 4 2more saline groundwater (cluster 2) (TDS>3000 mg L-1) resulting from replacement of Ca by Na through cation exchange process on clay minerals. Cluster 3 is high TDS (>7000 mg L-1) NaCl waters from the aquifer system under confined conditions. Clusters 1 and 2 are located in preferential recharge zones whereas cluster 3 characterises downstream of the study area. Overall, a groundwater quality decrease has been observed similarly with a salinity increase from downstream to upstream towards the coast, where cation exchange processes and salinisation due to the long residence times appear to be the main processes responsible of more salty waters.
Environmental Geology, 2008
Hydrochemistry of groundwater is largely determined by both natural processes, such as dissolution, cation exchange, mixing, evaporation; and anthropogenic activities, which can affect the aquifer systems by contaminating them or by modifying their hydrological cycle. Both natural and anthropogenic processes vary in time and space; which is reflected in groundwater hydrochemistry variation. The objective of this study is the determination of the main hydrogeochemical processes that affect the quality of shallow groundwaters in the Grombalia basin, located in the Cap Bon Peninsula, northeastern Tunisia. In this area, the chemical composition of groundwater is mostly characterized by Na-Cl-NO 3-Ca water type which reveals the implication of natural and anthropogenic major factors. Natural factors are dissolution of evaporatic minerals, i.e. halite and gypsum and cation exchange with clays, while anthropogenic factors are pollution with industrial Sr-rich waste water and return flow of irrigation water, highly contaminated by MgSO 4 and methyl-bromide fertilizers.
Journal of Environmental Science and Engineering Technology, 2014
Groundwater contamination has been recognized as one of the most serious problems in semi-arid and arid area (e.g. Zarzis aquifer, south-eastern Tunisia). The groundwater chemistry evolves rapidly and the salinity goes up considerably. A geochemical survey was carried out in which 23 groundwater samples were collected. EC, pH, TDS and major ions were measured and analyzed. Geochemical modeling, Piper Diagram, Q-mode hierarchical cluster and PCA were used to assess groundwater mineralization processes. Spatial variability of the different groundwater parameters was examined using semivariogram analysis. Results revealed that the Na-Cl-Ca-SO4-K is the dominant water type, suggesting rock-water interaction and dissolution of NaCl, CaSO4, 2H2O and KCl from sebkhas to be the main processes controlling groundwater mineralization in study area. Hierarchical Cluster Analysis (HCA) showed that groundwater is grouped in two clusters: the first, located in the southern part of the study area, ...
E3S Web of Conferences, 2020
Due to over-exploitation of water resources, the high basin of Guir posed an alarming risk of elimination in terms of quantity and quality. Therefore, this study intends to evaluate the physical and chemical quality of groundwater in the high Basin of Guir and to identify possible sources of pollution in order to map the quality of the Jurassic groundwater. During May 2018, thirty water points, distributed in the high basin of Guir, were sampled and analysed to determine concentrations of sevenchemical elements: K+, Na+, Ca++, Mg++, Cl-, HCO3-, SO4-. In addition, EC (Electric Conductivity), pH,T° and the piezometric level (PL) weremeasured.To study and compare, we treated statistically all data by Principal Component Analysis (PCA) and SIG.Analysis of the overall quality of water displayed results that range from good to poor quality. The degradation of water quality in the aquifer of the high basin of Guir could be geological and anthropic.
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The study area of Ain Oussera (3,790 km2) is located in the semi-arid high plains of the Saharian Atlas (200 km south of Algiers). Groundwater investigated in the present study is from the Albian formations which are considered as a major source for drinking and irrigation water. The objective of this study is to identify the different hydrochemical processes controlling the groundwater mineralization. For this purpose, chemical analyses were performed on 31 wells sampled during May 2014. The chemical study (total dissolved solids (TDS), Piper, chemical correlation) allowed the origins of groundwater mineralization to be identified. The dissolution of evaporate minerals, precipitation of carbonate minerals, and ion exchange reactions have been identified as major sources of mineralization processes. Anthropogenic processes due to human activities (sewage effluents and agricultural fertilizers) also contribute to the mineralization of the water. The results of principal component anal...
Journal of African Earth Sciences, 2014
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Arabian Journal of Geosciences, 2013
A hydrogeochemical approach has been carried out in the Mio-Plio-Quaternary aquifer system of northern Sfax to investigate the geochemical evolution, the origin of groundwaters and their circulation patterns. The groundwater samples collected from different wells seem to be dominated by sodium chloride type to sulphate chloride type. Detail analysis of chemical data including the thermodynamic calculations was used to assess that the chemical evolution of groundwater is primarily controlled by water-rock interactions. The values of sodium absorption ratio and electrical conductivity of the groundwater were plotted in the US Salinity Laboratory diagram for irrigation water. Most of the water samples in northern Sfax fall in the fields of C4S1, C4S2 and C4S3 indicating very high salinity and medium to high sodium alkalinity hazard. Thus, groundwater quality is ranging between doubtful to unsuitable for irrigation uses under normal condition, and further action for salinity control is required in remediating such problem. Principal component analysis of geochemical data used in conjunction with bivariate diagrams of major elements indicates that groundwater mineralization is mainly controlled by (1) water-rock interaction processes, (2) anthropogenic process in relation with return flow of NO 3-rich irrigation waters and (3) domestic discharges.
Arabian Journal of Geosciences, 2017
The major ion hydrochemistry, sodium absorption ratio (SAR), sodium percentage, and isotopic signatures of Hammamet-Nabeul groundwaters were used to identify the processes that control the mineralization, irrigation suitability, and origin of different water bodies. This investigation highlights that groundwater mineralization is mainly influenced by water-rock interaction and pollution by the return flow of irrigation water. The comparison of groundwater quality with irrigation suitability standards proves that most parts of groundwater are unacceptable for irrigation and this longterm practice may result in a significant increase of the salinity and alkalinity in the soils. Based on isotopic signatures, the shallow aquifer groundwater samples were classified into (i) waters with depleted δ 18 O and δ 2 H contents, highlighting recharge by modern precipitation, and (ii) waters with enriched stable isotope contents, reflecting the significance of recharge by contaminated water derived from the return flow of evaporated irrigation waters. The deep-aquifer groundwater samples were also classified into (i) waters with relatively enriched isotope contents derived from modern recharge and mixed with shallow-aquifer groundwater and (ii) waters with depleted stable isotope contents reflecting a paleoclimatic origin. Tritium data permit to identify three origins of recharge, i.e., contemporaneous, post-nuclear, and pre-nuclear. Carbon-14 activities demonstrate the existence of old paleoclimatic recharge related to the Holocene and Late Pleistocene humid periods.
Journal of African Earth Sciences, 2013
Major element concentrations, stable (d 18 O and d 2 H) and radiogenic (3 H, 14 C) isotopes determined in groundwater provided useful initial tracers for understanding the processes that control groundwater mineralization and identifying recharge sources in semi-arid Cherichira basin (central Tunisia). Chemical data based on the chemistry of several major ions has revealed that the main sources of salinity in the groundwaters are related to the water-rock interaction such as the dissolution of evaporitic and carbonate minerals and some reactions with silicate and feldspar minerals. The stable isotope compositions provide evidence that groundwaters are derived from recent recharge. The d 18 O and d 2 H relationships implied rapid infiltration during recharge to both the Oligocene and Quaternary aquifers, with only limited evaporation occurring in the Quaternary aquifer. Chemical and isotopic signatures of the reservoir waters show large seasonal evolution and differ clearly from those of groundwaters. Tritium data support the existence of recent recharge in Quaternary groundwaters. But, the low tritium values in Oligocene groundwaters are justified by the existence of clay lenses which limit the infiltration of meteoric water in the unsaturated zone and prolong the groundwater residence time. Carbon-14 activities confirm that groundwaters are recharged from the surface runoff coming from precipitation.
Arabian Journal of Geosciences, 2013
Gafsa region is one of the most productive artesian basins in Southern Tunisia. It is located in the southwestern part of the country, and its groundwater resources are developed for water supply and irrigation. Proper understanding of the geochemical evolution of groundwater is important for sustainable development of water resources in this region. A hydrogeochemical survey was conducted on the Plio-Quaternary shallow and on the Complex Terminal aquifers system using major (Ca, Mg, Na, SO 4 , Cl, NO 3 and HCO 3) and minor (Sr) elements, in order to evaluate the groundwater chemistry patterns and the main mineralization processes occurring in this system. Hydrochemical and isotopic data were used in conjunction with hydrogeological characteristics to investigate the groundwater composition in these aquifers. It has been demonstrated that groundwaters acquire their mineralization principally by water-rock interaction, i.e. dissolution of evaporites (halite/gypsum, pyrite, etc.) and return flow of irrigation waters, and by anthropogenic activities due to the use of nitrogen (N) fertilizers-pesticides in agriculture. The isotopic study of "stable isotopes, radiocarbon and tritium" (Yermani 2002) shows that a paleoclimatic recharge is corroborated by the relatively low carbon-14 activities (5-25.3%) of the referred groundwater group samples, which were interpreted as recharge occurring during the late Pleistocene and the early Holocene periods. The water feedings of these aquifers are mainly provided by infiltration of precipitations, infiltration of irrigation water, lateral feeding from Cretaceous relieves from the South and the North and along recent and fossil drainage networks that constitute major freshwater sources in groundwater tables (Hamed et al., J Environ Protect 1:466-474, 2010a).