Delineation of groundwater provenance in a coastal aquifer using statistical and isotopic methods, Southeast Tanzania

Global aquifers dominated by fossil groundwaters but wells vulnerable to modern contamination

“…First, our groundwater 14 C dataset is necessarily weighted toward permeable sedimentary basins because these tend to have greater groundwater resources and thus more groundwater wells. These permeable basins plausibly support deeper penetration of younger, Holocene-aged waters than less geologically permeable regions where groundwater drilling is rarer and thus groundwater 14 C data are less available. Thus, the radiocarbon data used in this analysis may be biased towards areas with deeper young groundwater, biasing our calculations toward small fossil groundwater abundances.…”

Groundwater residence time and paleorecharge conditions in the deep confined aquifers of the coastal watershed, South-East Tanzania

“…The physicochemical characteristics of the water samples are previously described in detail by Bakari et al (2012). From the hydrochemical point of view, the coastal aquifer may be divided into two parts, with different hydrogeochemical characteristics (Fig.…”

“…Previous studies on the coastal aquifer system of Tanzania have dealt with the geochemistry of shallow groundwater at the Kigamboni peninsula, along the Dar es Salaam coastal strip (Nkotagu, 1989), and the issue of saline water intrusion in the Mtwara region, assessed using geophysical methods (Gondwe, 1991). In a preceding publication by Bakari et al (2012), major factors governing groundwater quality were examined by means of multivariate statistical analyses, using chemical tracers and stable isotope signatures. The aim of the present study is to estimate groundwater residence time and paleorecharge conditions of groundwater from the Late Pleistocene to Holocene Period.…”

Hydrogeochemical assessment of a coastal aquifer using statistical and geospatial techniques: case study of Mombasa North Coast, Kenya

“…The combined effects of these factors dictate the groundwater type; however, the hydrogeochemical processes in the aquifer may also undergo variations in space and time (Belkhiri and Mouni 2013;Sheikhy Narany et al 2014). Some established methods for investigating the nature of coastal aquifers are: hydrochemical approaches using graphical and multivariate statistical methods (Banoeng-Yakubo et al 2009;Okiongbo and Douglas 2014;Ziani et al 2016); numerical modelling (Volker et al 2002;Sindhu et al 2012); electrical sounding methods (Olayinka et al 2004;Yan et al 2009); ground penetrating radar methods (Beres and Haeni 1991;Gulevich and Volkomirskaya 2015); GIS methods (Balathandayutham et al 2017;Durgadevagi et al 2016). Several statistical and graphical methods including: principal component analysis, cluster analysis, fuzzy k-means clustering, Collins bar diagram and Piper plot graphical methods have been examined and compared (Güler et al 2002).…”

“…A further groundwater study was conducted in the same region to identify the main hydrogeochemical processes controlling the quality of groundwater as well as the possibility of anthropogenic pollution and seawater intrusion (Mtoni et al 2013). Another study was conducted on the coastal aquifer of South East Tanzania to detect the groundwater sources and the main factors influencing the groundwater quality with the aid of multivariate statistical analyses (Bakari et al 2011). Sappa et al (2015) applied techniques such as principal component analysis (PCA), pattern diagrams and geochemical modelling techniques in identifying the major factors influencing the composition of the groundwater on a seasonal scale and assessing the influence of seasonal changes on groundwater chemistry.…”