Environmental Earth Sciences

, Volume 66, Issue 3, pp 889–902 | Cite as

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

  • Said Suleiman BakariEmail author
  • Per Aagaard
  • Rolf D. Vogt
  • Fridtjov Ruden
  • Ingar Johansen
  • Said Ali Vuai
Original Article


Rapid population growth and urbanization has placed a high demand on freshwater resources in southeast costal Tanzania. In this paper, we identify the various sources of groundwater and the major factors affecting the groundwater quality by means of multivariate statistical analyses, using chemical tracers and stable isotope signatures. The results from hierarchical cluster analyses show that the groundwater in the study area may be classified into four groups. A factor analysis indicates that groundwater composition is mainly affected by three processes, accounting for 80.6% of the total data variance: seawater intrusion, dilution of groundwater by recharge, and sewage infiltration. The hydrochemical facies of shallow groundwater was mostly of the Na–Ca–Cl type, although other water types were also observed. The deep groundwater samples were slightly to moderately mineralized and they were of the NaHCO3 type. This water type is induced mainly by dissolution of carbonate minerals and modified by ion exchange reactions. The signal from the stable isotope composition of the groundwater samples corresponded well with the major chemical characteristics. In the shallow groundwater, both high-nitrate and high-chloride concentrations were associated with localized stable isotope enrichments which offset the meteoric isotopic signature. This is inferred to be due to the contamination by influx of sewage, as well as intrusion by seawater. The depleted stable isotope values, which coincides with a chemical signature for the deep aquifer indicates that this deep groundwater is derived from infiltration in the recharge zone followed by slow lateral percolation. This study shows that a conceptual hydrogeochemical interpretation of the results from multivariate statistical analysis (using HCA and FA) on water chemistry, including isotopic data, provides a powerful tool for classifying the sources of groundwater and identifying the significant factors governing the groundwater quality. The derived knowledge generated by this study constitutes a conceptual framework for investigating groundwater characteristics. This is a prerequisite for developing a sound management plan, which is a requirement for ensuring a sustainable exploitation of the deep aquifer water resource in the coastal area of Tanzania.


Groundwater Multivariate statistical analyses Stable isotopes Costal aquifer Tanzania 



This research was financially supported by the Quota Scheme Programme and the Department of Geosciences, University of Oslo. We thank the local owners of the private wells and the Dar es Salaam Water Supply Authority (DAWASA) Manager for granting us access to the wells. The authors are extremely grateful to Mr. Addo Ndimbo (Ardhi University-Dar es Salaam, Tanzania) for his support during the sampling phase of this work. We are also indebted to technicians in the Department of Geosciences laboratory, University of Oslo, for their efficient assistance in the analysis of water samples. The authors are extremely grateful to Prof. Hans Martin Seip (Department of Chemistry, University of Oslo) for earlier comments, which are greatly appreciated. The constructive comments from the journal editors and anonymous reviewers followed by the language-review done by Ms. Amy Dale from GeoResearch Consulting, Skarnes, Norway, improved the quality of the manuscript.


  1. Adams S, Titus R, Pietesen K, Tredoux G, Harris C (2001) Hydrochemical characteristic of aquifers near Sutherland in the Western Karoo, South Africa. J Hydrol 241:91–103CrossRefGoogle Scholar
  2. Andreasen DC, Fleck WB (1997) Use of bromide: chloride ratios to differentiate potential sources of chloride in a shallow, unconfined aquifer affected by brackish-water intrusion. Hydrogeol J 5:17–26CrossRefGoogle Scholar
  3. Appelo CAJ (1996) Multicomponent ion exchange and chromatography in natural systems. Rev Mineral 34:193–227Google Scholar
  4. Appelo CAJ, Postma D (1993) Geochemistry, groundwater and pollution. Balkema, Rotterdam, p 519Google Scholar
  5. Appelo CAJ, Postman D (2005) Geochemistry, groundwater and pollution, 2nd edn. Balkema, Rotterdam, p 459CrossRefGoogle Scholar
  6. Burnett WC, Aggarwal PK, Aureli A et al (2006) Quantifying submarine groundwater discharge in the coastal zone via multiple methods. Sci Total Environ 367:498–543CrossRefGoogle Scholar
  7. Ceron JC, Jimenez-Espinosa R, Pulido-Bosch A (2000) Numerical analysis of hydrogeochemical data: a case study (Alto Guadalentõan, southeast Spain). Appl Geochem 15:1053–1067CrossRefGoogle Scholar
  8. Clark ID, Fritz P (1997) Environmental isotopes in hydrogeology. CRC, Boca RatonGoogle Scholar
  9. Cook P, Herczeg AL (2000) Environmental tracers in subsystem hydrology. Kluwer Academic Publishers, New YorkCrossRefGoogle Scholar
  10. Craig H (1961) Isotopic variation in meteoric waters. Sci 133:1702–1703CrossRefGoogle Scholar
  11. Dansgaard W (1964) Stable isotope in precipitation. Tellus 16(4):436–468CrossRefGoogle Scholar
  12. Faure G, Mensing TM (2005) Isotopes: principles and applications, 3rd edn. Wiley, USA, pp 691–743Google Scholar
  13. Gondwe E (1991) Saline water intrusion in southeast Tanzania. Geoexploration 27(1–2):25–34CrossRefGoogle Scholar
  14. Hach (1992) Digital titrator model 16900–01 manual. Hach Company, LovelandGoogle Scholar
  15. Helina B, Pardo R, Vega M, Barrado E, Fernandez JM, Fernandez L (2000) Temporal evolution of groundwater composition in an alluvial aquifer (Pisuerga River, Spain) by principal component analysis. Water Res 34:807–816CrossRefGoogle Scholar
  16. JICA Report (2005) The study on water supply improvement in Coast Region and Dar es Salaam peri-urban in the United Republic of Tanzania-final report. Japan International Cooperation Agency (JICA), Dar es Salaam, TanzaniaGoogle Scholar
  17. Johnston RH (1983) The saltwater–freshwater interface in the Tertiary limestone aquifer, southeast Atlantic outer-continental shelf of the USA. J Hydrol 61:239–249CrossRefGoogle Scholar
  18. Kent PE, Hunt JA, Johnstone DW (1971) The geology and geophysics of coastal Tanzania. Geophysical paper 6. Her Majesty’s Stationary Office (HMSO), London, pp 20–25Google Scholar
  19. Kharaka YK, Carothers WW (1986) Oxygen and hydrogen isotope geochemistry of deep basin brines. In: Fritz P, Fontes JC (eds) Handbook of environmental isotope geochemistry, vol 2. Elsevier, Amsterdam, pp 305–361Google Scholar
  20. Kim Y, Lee KS, Koh DC, Lee DH, Lee SG, Park WB, Koh GW, Woo NC (2003) Hydrogeochemical and isotopic evidence of groundwater salinization in a coastal aquifer: a case study in Jeju volcanic island, Korea. J Hydrol 270:282–294CrossRefGoogle Scholar
  21. Kim JH, Kim RH, Lee J, Cheong TJ, Yum BW, Chang HW (2005a) Multivariate statistical analysis to identify the major factors governing groundwater quality in the coastal area of Kimje, South Korea. Hydrol Process 19:1261–1276CrossRefGoogle Scholar
  22. Kim JH, Lee J, Cheong TJ, Kim RH, Koh DC, Ryu JS, Chang HW (2005b) Use of time series analysis for the identification of tidal effect on groundwater in the coastal area of Kimje, Korea. J Hydrol 300:188–198CrossRefGoogle Scholar
  23. Lee JY, Cheon JY, Lee KK, Lee SY, Lee MH (2001) Statistical evaluation of geochemical parameter distribution in a ground water system contaminated with petroleum hydrocarbons. J Environ Quality 30:1548–1563CrossRefGoogle Scholar
  24. Liu CW, Lin KH, Kuo YM (2003) Application of factor analysis in the assessment of groundwater quality in a blackfoot disease area in Taiwan. Sci Total Environ 313:77–89CrossRefGoogle Scholar
  25. Ministry of Water (2006) MAJI review (Draft). The United Republic of Tanzania, Dar es SalaamGoogle Scholar
  26. Morell I, Gimenez E, Esteller MV (1996) Application of principal components analysis to the study of salinization on the Castellon Plain Spain. Sci Total Environ 177:161–171CrossRefGoogle Scholar
  27. Nicholson SE (1996) A review of climate dynamics and climate variability in Eastern Africa. In: Johnson TC, Odada EC (eds) The limnology, climatology and paleoclimatology of the East African Lakes. Gordon and Breach, Amsterdam, pp 25–56Google Scholar
  28. Nkotagu H (1989) Geochemistry of shallow groundwater at Kigamboni peninsula along Dar es Salaam coastalstrip Tanzania. J Afican Earth Sci 9(3–4):739–748CrossRefGoogle Scholar
  29. Nkotagu H (1996) Application of environmental isotopes to groundwater recharge studies in a semi-arid fractured crystalline basement area of Dodoma, Tanzania. J African Earth Sci 22(4):443–457CrossRefGoogle Scholar
  30. Norwegian Consultancy (NORCONSULT) (2008) Development of a future water source for Dar es Salaam. supervision status report: Sites Kimbiji, Mpiji and Mpera. Ruden Aquifer Development Ltd, N-1628 Engelsviken, Norway for NIVA/NORCONSULTGoogle Scholar
  31. Ozler HM (2003) Hydrochemistry and salt–water intrusion in the Van aquifer, east Turkey. Environ Geol 43:759–775Google Scholar
  32. Parkhurst DL, Appelo CAJ (1999) User’s guide to PHREEQC (version 2)—a computer program for speciation, reaction-path, advective-transport, and inverse geochemical calculations: US Geological Survey—Water Resources Investigations report. US Geological Survey, Denver, pp 99–4259Google Scholar
  33. Richter BC, Kreitler CW (1993) Geochemical techniques for identifying sources of ground-water salinization. CRC Press, Boca Raton, p 258Google Scholar
  34. Rietti-Shati M, Yam R, Karlen W, Shemesh A (2000) Stable isotope composition of tropical high-altitude fresh-waters on Mt. Kenya, Equatorial East Africa. Chem Geol 166:341–350CrossRefGoogle Scholar
  35. Ruden F (2007) The discovery of a regional Neogene aquifer in coastal Tanzania. Coastal aquifers: challenges and solutions 1. Instituto Geológicoy Minerode Espaňa, Madrid, pp 363–372Google Scholar
  36. Stigter TY, Carvalho Dill AMM, Ribeiro L, Reis E (2006) Impact of the shift from groundwater to surface water irrigation on aquifer dynamic and hydrochemistry in a semi-arid region in the south of Portugal. Agric Water Manag 85(1–2):121–132CrossRefGoogle Scholar
  37. Stoessell RK (1997) Delineating the chemical composition of the salinity source for the saline groundwaters: an example from East-Central Concordia Parish, Louisiana. Ground Water 35:409–417CrossRefGoogle Scholar
  38. Suk H, Lee KK (1999) Characterization of a ground water hydrochemical system through multivariate analysis: clustering into ground water zones. Ground Water 37:358–366CrossRefGoogle Scholar
  39. Thyne G, Guler C, Poeter E (2004) Sequential analysis of hydrochemical data for watershed characterization. Ground Water 42:711–723CrossRefGoogle Scholar
  40. Tijani MN (2004) Evolution of saline waters and brines in the Benue-Trough, Nigeria. Appl Geochem 19:1355–1365CrossRefGoogle Scholar
  41. TPDC (2007) Accessed 15 December 2007
  42. Vogt et al (2001) IMPACTS catchment manual. Accessed 17 Feb 2009
  43. WHO (2004) Guidelines for drinking-water quality, 3rd edn, vol 1. Recommendations. World Health Organization, GenevaGoogle Scholar
  44. Word JH (1963) Hierarchical grouping to optimize an objective function. J Am Stat Assoc 58:236–244Google Scholar

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Said Suleiman Bakari
    • 1
    Email author
  • Per Aagaard
    • 1
  • Rolf D. Vogt
    • 2
  • Fridtjov Ruden
    • 3
  • Ingar Johansen
    • 4
  • Said Ali Vuai
    • 5
  1. 1.Department of GeosciencesUniversity of OsloOsloNorway
  2. 2.Department of ChemistryUniversity of OsloOsloNorway
  3. 3.Ruden Aquifer Development LtdEngelsvikenNorway
  4. 4.Department of Environmental TechnologyInstitute for Energy TechnologyKjellerNorway
  5. 5.Department of Physical SciencesThe University of DodomaDodomaTanzania

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