Hydrochemical classification and multivariate statistical analysis of groundwater from Wadi Sahba area in central Saudi
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ORIGINAL PAPER
Hydrochemical classification and multivariate statistical analysis of groundwater from Wadi Sahba area in central Saudi Arabia Talal Ghazi Alharbi 1 & Faisal Kamal Zaidi 1 Received: 5 March 2018 / Accepted: 1 October 2018 / Published online: 24 October 2018 # Saudi Society for Geosciences 2018
Abstract The central region of Saudi Arabia is underlain by thick sedimentary formations belonging to the Mesozoic and Cenozoic era. These sedimentary formations form a prolific aquifer supplying groundwater for agricultural and domestic usage in and around Riyadh. The region south of Riyadh City is well known for agricultural activities. Wadi Sahba, which is an eastward extension of Wadi Nisah, has readily available groundwater resources in the Cretaceous Biyadh sandstone aquifer to sustain agricultural activities. The objective of the present study was the hydrochemical assessment of groundwater in the area to understand the main hydrological processes which influence groundwater chemistry. To achieve this objective, 20 groundwater samples were collected from agricultural farms in the Wadi Sahba in central Saudi Arabia, and the major physiochemical constituents were analyzed and interpreted. The average TDS value of the analyzed samples is 1578.05 mg/l, whereas the average EC concentration is 3220.05 μS/cm. Groundwater facies classification inferred from the Piper plot shows that groundwater in the study area belongs to the Ca-SO4-Cl type and Ca-Na-SO4-Cl type. The Ca-SO4-Cl type of groundwater facies is influenced mainly by gypsum dissolution and base ion exchange, whereas the Ca-Na-SO4-Cl type is influenced by gypsum and halite dissolution. All the groundwater samples are undersaturated with respect to these two principal mineral phases. The Q-mode cluster analysis results in two main groups of groundwater samples, mainly based on the TDS content. Cluster 1 has an average TDS value of 1980 mg/l, whereas cluster 2 has an average TDS of 1176 mg/l. The groundwater facies identified through the Piper plot reflects the major hydrological processes controlling groundwater chemistry in the area and was found to be more useful in this study as compared to cluster analysis. Keywords Hydrochemical classification . Cluster analysis . Arid region . Saudi Arabia . Biyadh Wasia aquifer system
Introduction Thirty percent of the Earth’s land surface is covered by arid and semiarid regions and includes the Arabian Peninsula, North Africa, Middle Asia, some parts of Europe, southwestern parts of the USA, southern parts of the South American continent, and Australia (Dregne 1991). These regions are characterized by very low rainfall and high evaporation rates; as a result, the groundwater recharge from precipitation is almost absent (Qin et al. 2011). Due to the absence of surface water supplies, the arid and semiarid areas rely heavily on the available groundwater reserves (Scanlon et al. 2006; Zaidi and Kassem 2012; * Faisal Kamal Zaidi [email protected] 1
Geology and Geophysics Department, College of Science, King Saud
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