Multivariate Statistical Analysis of the Groundwater of Ain Djacer Area (Eastern of Algeria)
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Arab J Geosci (2016) 9:248 DOI 10.1007/s12517-015-2277-6 ORIGINAL PAPER Multivariate statistical analysis of the groundwater of Ain Djacer area (Eastern of Algeria) Said Bencer 1 & Abderrahmane Boudoukha1 & Lotfi Mouni2 Received: 3 January 2015 /Accepted: 18 December 2015 # Saudi Society for Geosciences 2016 Abstract The intensive exploitation of groundwater re- salt formations. The presence of nitrates is related to agricul- sources in the region of Ain Djacer has greatly influenced tural activity. the hydrochemical functioning of the superficial aquifer. This has resulted in a general decline of the piezometric level Keywords Multivariate statistical . Principal component of the groundwater, a mineralization of water and calcium analysis . Cluster analysis . Hydrochemistry . Groundwater . facies near limestone and sodium chloride in the center of Algeria the plain in liaison with the lithology. To highlight the hydrochemical processes of groundwater, a study by major ions were analyzed in 21 groundwater samples collected from Introduction this aquifer during the month of March 2004. Multivariate statistical techniques and cluster and principal component The groundwater quality is influenced by many factors, such analysis were applied to the data on groundwater quality, with as the chemistry of infiltration water, the geological nature of the objective of defining the main controls on the the reservoir rock, the decomposition of organic matter, and hydrochemistry at the plain. These statistical techniques have anthropogenic factors (Frape et al. 1984). The dissolution of shown the presence of three salinity groups with increasing minerals from the surrounding rock in the water is the domi- importance according to the direction of flow. The initial fa- nant factor controlling the chemical composition of these wa- cies on the limits as well as infiltration areas is bicarbonate. In ters. Some minerals such as carbonates and evaporates rapidly the center of the plain, water becomes charged with sodium dissolved and significantly changed the chemical composition (Na) and chlorine (Cl) in connection with the dissolution of of the water, while others such as mineral silicates dissolved more slowly and therefore have less effect on the chemical composition of water (Garrels and MacKenzie 1967). The temperature also has an essential role in the chemical compo- * Abderrahmane Boudoukha sition of groundwater (Hem 1989; Boudoukha and Athamena [email protected] 2012). Most studies as Hartman et al. (2005), Adams et al. (2001), and Alberto et al. (2001) showed that the groundwater Said Bencer chemistry is mainly a function of the interaction between wa- [email protected] ter and mineralogical composition of the aquifer. Lotfi Mouni Hydrochemical processes occurring within this system are [email protected] dissolution, precipitation, and ion exchange. These phenome- na occur along the groundwater flow and also depend on the 1 Laboratory of Applied Research in Hydraulics, University of residence time which controls the evolution of the chemical Batna 2, Road of Constantine, 05078 Fesdis-Batna, Algeria composition of groundwater (Apodaca et al. 2002). Several 2 Laboratory of Management and Valuation of Natural Resources and statistical techniques have been applied to study, assess, and Quality Assurance. SNVST Faculty, University of Akli Mohand characterize the chemical changes in groundwater as cluster Oulhadj, 10000 Bouira, Algeria analysis (CA) and principal component analysis (PCA) 248 Page 2 of 10 Arab J Geosci (2016) 9:248 (Belkhiri et al. 2010). Meng and Maynard (2001); Farnham Geological and hydrogeological setting et al. (2003) used FA to discuss geochemical evolution and mineralization and groundwater contamination. Additionally, The geological setting of the area was established from a de- the CA was also used to interpret the hydrochemical data tailed surface geological map of the area (Wildi 1983; Vila based on factor scores, for example, (Suk and Lee 1999; 1980). Five main units are identified as follows: (1) Triassic Reghunath et al. 2002; Kim et al. 2005). This technique was saliferous, (2) Jurassic carbonate, (3) Cretaceous carbonate, used to study the chemical evolution of water along the (4) Mio-Pliocene, and (5) Quaternary. Figure 1.Triassic groundwater flow by many researchers such as (Plummer saliferous diapir is found in the northern part of the study area et al. 1990; Rosenthal et al. 1998; Eary et al. 2002; Güler in Chouf Rherab. This unit is composed by crushed ice and and Thyne 2002). hand complex limestone dolomitic. Jurassic and Cretaceous Several techniques have been applied to study, assess, and carbonate formation are formed by dolomitic limestone and characterize the chemical changes in groundwater, such as sandstone, sometimes with thick marl layers of about 550-m thermodynamic equilibrium that defines the chemical evolu- thick. The Mio-Plio-Quaternary formation is a heterogeneous tion of groundwater. For this, the tendency of chemical forms continental detrital sedimentation. It is corresponding to red between the dissolved phase and the inorganic phase was ex- clay, sometimes gypsum overcome by lacustrine limestones, amined by the saturation index. This expresses the degree of conglomerates, and alluvium. The thickness of this formation chemical equilibrium between water and the inorganic matrix varies between 300 and 500 m (Boudoukha 1988). in the aquifer and can be considered a measure of the dissolu- Mineralogically, most of the soils are dominated by kaolinite, tion and/or precipitation in the study of water–rock interaction illite, smectite, and chlorite, typical for most arid and semi- (Gibbs 1970; Drever 1997). The use of code PHREEQ-C arid soils. The presence of smectite suggests specific sites for allows calculating the saturation indices of some carbonate sodium adsorption (Belkhiri and Mouni 2013). and evaporating minerals (Parkhurst and Appelo 1999). Tectonics of the region led to the formation of a syncline The objective of the present work was to characterize the filled with detrital elements, of Mio-Plio-Quaternary age. The chemistry of groundwater and determine the origin of the superposition of several tectonic phases allowed the Triassic chemical elements present in the waters of the plain of Ain carbonate formations staked Triassic and development of se- Djacer in Algeria, by using the multivariate statistical vere fracture network direction southwest, northeast, north- techniques. west, and southeast. The studied area is situated in the alluvial plain of the Mio-Plio-Quaternary showing a heterogeneous continen- tal detrital sedimentation. This aquifer is constituted by Materials and methods very varied deposits such as alluvial fans, silts, calcare- ous crust, conglomerates, and gravels. This shallow Study area: general overview groundwater mainly occurs 10–100 m below the surface, 10 m in these limits and 100 m in the center of the plain. The investigated area is located in the East of Algeria. Most of The substratum of the shallow groundwater is formed by inhabitants (more than 20,000 inhabitants) are centered on the clays and marls; sometimes are gypsum of Mio-Pliocene. town of Ain Djacer. The principal activity in this area is the The pumping tests on different wells showed high trans- production of cereals (barley and corn), and its climate is missivity (10−4 m/s) indicating high yields. Groundwater semi-arid. Ain Djacer region is centered on latitude 35°49′ is recharged by vertically infiltrating meteoric water in 50″N and longitude 6°00′16″E. The catchment area of Ain the basin and by stream water coming from different Djacer covering an area of 210 km2 is a relatively flat terrain reliefs surrounding the depression intermountainous of and very low slope. The topography of the plain is nearly flat the plain. Since 1997 to 2013 (Chabour 1997;Bencer with a slope not exceeding 2 %, and the highest altitude 2005;Ziani2009), the water table has maintained the is 865 m. This morphology allowed the installation of a same structure, characterized by the presence of two low temporary hydrographic network. This hydrographic zones, the first in the west with a west–east flow and network is drained by a set of topographic depressions the second in the east with an east–west flow. The mor- further north creating an endorheic drainage network. phology of the water table was imposed by the syncline The region is characterized by annual rainfall of about structure of the substratum. These two flows converge 260 mm and an annual mean temperature 15.9 °C towards the center of the plain for being drained to the (Mebarki 2009). The establishment of water balance ac- north. This piezometric state shows that the aquifer has a cording to Thornthwaite formula over in the past limitation of inflow from carbonate massifs which sur- 20 years (1993 to 2013) in the station of Batna airport round the plain to the west, south, and east and a dis- showsthatthisregionisindeficit. charge to the north. Arab J Geosci (2016) 9:248 Page 3 of 10 248 Fig. 1 Hydrogeological map of Ain Djacer area Sample collection and methods an ice chest at a temperature of <4 °C and later trans- ferred to the laboratory of the National Agency for Water To examine the evolution of the physicochemical parameters, Resources of Constantine and stored in a refrigerator at a 21 samples were taken during the month of March 2004. The temperature of <4 °C until they have been analyzed samples were collected after pumping