Modelling Seawater Intrusion into Multi-layered Aquifer System of Lagos Area, Nigeria

O. S. Abiola, A. O. Agbede


Investigation as indicated that in the immediate vicinity of Lagos metropolitan, four separate aquifers are tapped. Over-exploitation of these aquifers through boreholes for both domestic and industrial water supply has resulted in salt water intrusion occurring in the confined aquifers. Monitoring and management of salt water intrusion is not done in Nigeria hence there is a need to study and ascertain the extent of sea water intrusion along the coastal region of Nigeria.

Data were collected from the boreholes within the studied area to model a two-dimensional advection-dispersion problem. The basic differential equation was solved for two-dimensional transport in an incompressible porous medium and transport in the absence of sources.  The velocity flow was solved as a separate problem, independent of the solution for the concentration. A computer program was developed to solve the two dimensional dispersion problems by the finite element method. The model was calibrated in two steps, with the transient runs modelling Chloride concentration for the three aquifers. The runs simulated the 1982 and 1996 chloride concentration and predicted what condition it will be in 2010.

The result indicated that the area of chloride concentration increased from 13km2 in 1996 to 38km2for upper coastal plains sands while the concentration increases from 68mg/L to 83mg/L. Comparing the simulated chloride for all the three aquifers Abeokuta formation has the lowest value of chloride concentration. This confirms that Abeokuta formation is freshwater aquifer. Generally the results obtained for chloride concentration agrees with report of Coode Blizard Ltd.


Seawater intrusion, Aquifer, Chloride concentration, Coastal plain sands, Model

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Abd-Elhamid, H.F and Javadi, A.A. (2008). An Investigation into control of saltwater

intrusion considering the effects of climate change and sea level rise. Proceedings of

th Saltwater Intrusion meeting, Naples, Florida, USA, pp: 4-7.

Bastani, M., Rakshandehroo, G.R and Kholghi, M. (2008). Study of saltwater intrusion

into coastal aquifer of Tavabe-e Arsanjan, Iran. Proceedings of 20th Saltwater

Intrusion meeting, Naples, Florida, USA, 217-220.

Bear, J and Kapuler, I. (1981). A numerical Solution for movement of an Interface in a

Layered Coastal aquifer. J. Hydrol. 50, pp: 273-298.

Cheng, J. R., Strobl, R. O., Yeh, G.T., Lin, H.C. and Choi, W. H. (1998). Modelling of

-D density dependent flow and transport in the subsurface. J. Hydro. Eng., 3(4),


Coode Blizard Ltd., Akute Geo-Resource Ltd. and Rofe Kennard & Lapworth (1996).

Hydrogeological Investigation of Lagos State. Final Report, Vols I & II.

Frind, E. O. (1982). Simulation of long-term transient density-dependent transport in

groundwater. Adv. Water Resour, 5(2), 73-88.

Huyakorn, P. S. Andersen, P. F., Mercer, J.W. and White Jr., H. O. (1987). Saltwater

intrusion in aquifers: Development and testing of a three dimensional finite element

model. Water Resour. Res., 23(2), 293-312.

Huyakorn, P.S, Wu, Y.S and Park, N.S. (1996). Multi-phase approach to the Numerical

Solution of a Sharp interface Saltwater Intrusion problem. Water Resour. Res. 32

(1), 93-102.

Lafe, O. and Imala, F. (1985). An Analytic Model for groundwater flow in the Lagos

Metropolitan aquifer system. The Nigerian Engineer, vol. 20, No. 2, pp. 14-20.

Mualem, Y. and Bear, J. (1974). The Shape of the Interface in Steady flow in a

Stratified Aquifer. Water Resour. Res. 10 (6), 1207-1215.

Papadopoulou, M.P., Karatzas, G.P., Koukadaki, M.A. and Trichakis, Y. (2005).

Modelling the saltwater intrusion phenomenon in coastal aquifers- a case study 203.

Ranjan, P. (2007). Effect of climate change and land use change on saltwater intrusion.

In Encyclopaedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.:

Environmental Information Coalition, National Council for Science and


Sa da Costa, A.A.G. and Wilson, J.L. (1979). A Numerical Model of sea water intrusion

in aquifers. R.M Parsons Lab. Rept. No. 247, MIT, Cambridge, Mass. 245pp.

Sivapragasm, C., Jegatheesan, V., Arun, V.M. and Vanitha, S. (2010). Spatial

Modelling of Electrical Conductivity with Neural Network. Int. J. Eng. Sci. & Tech.

(7), 3128-3136.


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