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Hydrochemical evaluation of groundwater in the Blue Nile Basin, eastern Sudan, using conventional and multivariate techniques

Hussein, MohammedTahir
Hydrogeology journal 2004 v.12 no.2 pp. 144-158
aquifers, basins, bicarbonates, calcium, chlorides, correspondence analysis, electrical conductivity, fluorides, groundwater, ion exchange, magnesium, mineralization, mixing, multivariate analysis, pH, potassium, rain, rivers, sandstone, sodium, subsurface flow, sulfates, total dissolved solids, water quality, Sudan
Hydrochemical evaluation of groundwater systems can be carried out using conventional and multivariate techniques, namely cluster, factor analyses and others such as correspondence analysis. The main objective of this study is to investigate the groundwater quality in the Blue Nile basin of eastern Sudan, and to workout a hydrochemical evaluation for the aquifer system. Conventional methods and multivariate techniques were applied to achieve these goals. Two water-bearing layers exist in the study area: the Nubian Sandstone Formation and the Al-Atshan Formation. The Nubian aquifer is recharged mainly from the Blue Nile and Dinder Rivers through lateral subsurface flow and through direct rainfall in outcrop areas. The Al-Atshan aquifer receives water through underground flow from River Rahad and from rainfall infiltration. The prevailing hydrochemical processes are simple dissolution, mixing, partial ion exchange and ion exchange. Limited reverse ion exchange has been witnessed in the Nubian aquifer. Three factors control the overall mineralization and water quality of the Blue Nile Basin. The first factor includes high values of total dissolved solids, electrical conductivity, sodium, potassium, chloride, bicarbonate, sulphate and magnesium. The second factor includes calcium and pH. The third factor is due to fluoride concentration in the groundwater. The study highlights the descriptive capabilities of conventional and multivariate techniques as effective tools in groundwater quality evaluation.