Back
 JEP  Vol.4 No.5 , May 2013
Groundwater Vulnerability Assessment and Validation for a Fast Growing City in Africa: A Case Study of Lagos, Nigeria
Abstract: Lagos is the world’s sixth largest city, the most populous city in Africa and the most populous city inNigeria. A total of eighteen groundwater exploitation borehole logs together with hydrogeological and geotechnical data were used for the study. The eighteen available borehole logs were categorized into seven areas spanning the shoreline to inland boundary ofLagosState. The study area has a high net recharge of1838 mm/yr and the aquifer media is sand. The intrinsic vulnerability map show areas of highest potential for groundwater pollution based on hydro-geological condition and human impacts. Seven major hydro-geological factors incorporated into DRASTIC model and the geographic information system (GIS) were used to create a groundwater vulnerability map by overlaying the available hydro-geological data. The output map shows that the southeast of the aquifer is under very high vulnerability while central parts of aquifer have high vulnerability. Other parts (north, northwest and south) of the study area have moderate vulnerability to pollution. For testing of the vulnerability assessment, groundwater quality data were collated from literature for the different vulnerability zones of the study area. The chemical analysis results show that both the southeast and northwest west parts of study area aquifer (very high and moderate vulnerability zones) have higher nitrate concentration relative to the rest of aquifer, that are located in high vulnerability zone. The validation of the DRASTIC models was accomplished through pair wise comparison of DRASTIC vulnerability maps (using Pearson’s r correlation coefficient) with a total of 14 layers representing original DRASTIC input data, Land cover (LC) features, and groundwater TDS, Cl- and NO3 data. Results from the correlation analysis indicate a significant association between high groundwater TDS, NO3 concentrations and distances from certain LC types.
Cite this paper: O. Ojuri and O. Bankole, "Groundwater Vulnerability Assessment and Validation for a Fast Growing City in Africa: A Case Study of Lagos, Nigeria," Journal of Environmental Protection, Vol. 4 No. 5, 2013, pp. 454-465. doi: 10.4236/jep.2013.45054.
References

[1]   J. W. A. Foppen and J. F. Schijven, “Evaluation of Data from the Literature on the Transport and Survival of Escherichia coli and Thermotolerant Coliforms in Aquifers under Saturated Conditions,” Water Resources, Vol., 40, No. 3, 2006, pp. 401-426.

[2]   World Health Organization (WHO), “Global Water Supply and Sanitation Assessment 2000 Report,” 2013. http://www.who.int/water_sanitation_health/monitoring/globalassess/en/

[3]   R. C. M. Nobre, O. C. Rotunno Filho, W. J. Mansur, M. M. M. Nobre and C. A. N. Cosenza, “Groundwater Vulnerability and Risk Mapping Using GIS, Modeling and a Fuzzy Logic Tool,” Journal of Contaminant Hydrology, Vol., 94, No. 3, 2007, pp. 277-292. doi:10.1016/j.jconhyd.2007.07.008

[4]   L. Aller, T. Bennett, J. H. Lehr, R. Petty and G. Hackett, “DRASTIC: A Standardized System for Evaluating Ground Water Potential Using Hydrogeologic Settings,” United States Environmental Protection Agengy (USEPA), Ada, 1987.

[5]   S. S. D. Foster, “Fundamental Concepts in Aquifer Vulnerability, Pollution Risk and Protection Strategy,” Proceedings and Informations/TNO Committee on Hydrological Research, Vol. 38, 1987, pp. 36-86.

[6]   D. Van Stempvoort, L. Ewert and L. Wassenaar, “AVI: A Method for Groundwater Protection Mapping in the Prairie Provinces of Canada,” PPWD Groundwater and Contaminants Project, National Hydrology Research Institute, Saskatoon, 1992.

[7]   R. C. Palmer and M. A. Lewis, “Assessment of Groundwater Vulnerability in England and Wales,” In: N. S. Robins, Ed., Groundwater Pollution, Aquifer Recharge and Vulnerability, Geological Society Special Publication, Vol. 130, 1998, pp. 191-198.

[8]   I. S. Babiker, M. A. A. Mohamed, T. Hiyama and K. Kato, “A GISbased DRASTIC Model for Assessing Aquifer Vulnerability in Kakamigahara Heights, Gifu Prefecture, Central Japan,” Science of the Total Environment, Vol. 345, No. 1-3, 2005, pp. 127-140. doi:10.1016/j.scitotenv.2004.11.005

[9]   N. S. Robins, P. J. Chilton and J. E. Cobbing, “Adapting Existing Experience with Aquifer Vulnerability and Groundwater Protection for Africa,” Journal of African Earth Sciences, Vol. 47, No. 1, 2007, pp. 30-38. doi:10.1016/j.jafrearsci.2006.10.003

[10]   M. G. Rupert, “Calibration of the DRASTIC Ground Water Vulnerability Mapping Method,” Ground Water, Vol. 39, No. 4, 2001, pp. 630-635. doi:10.1111/j.1745-6584.2001.tb02350.x

[11]   I. R. Lake, A. A. Lovett, K. M. Hiscock, M. Betson, A. Foley, G. Sünnenberg, S. Evers and S. Fletcher, “Evaluating Factors Influencing Groundwater Vulnerability to Nitrate Pollution: Developing the Potential of GIS,” Journal of Environmental Management, Vol. 68, No. 3, 2003, pp. 315-328. doi:10.1016/S0301-4797(03)00095-1

[12]   T. C. Pizani, G. C. Silva Júnior and C. Bettini, “Vulnerability Assessment to Aquifer Contamination in Resende Sedimentary Basin, Brasil, with the DRASTIC Method,” International Society for Soil Mechanics & Geotechnical Engineering (ISSMGE) 4th International Congress on Environmental Geotechnical Engineering (ICEG), Rio de Janeiro, 12-16 August 2002, pp. 11-15.

[13]   D. Thirumalaivasan, M. Karmegam, K. Venugopal, “AHP-DRASTIC: Software for Specific Aquifer Vulnerability Assessment Using DRASTIC Model and GIS,” Environmental Modelling and Software, Vol. 18, No. 7, 2003, pp. 645-656. doi:10.1016/S1364-8152(03)00051-3

[14]   M. Chitsazan and Y. Akhtari, “A GIS-Based DRASTIC Model for Assessing Aquifer Vulnerability in Kherran Plain, Khuzestan, Iran,” Water Resources Management, Vol. 23, No. 6, 2009, pp. 1137-1155. doi:10.1007/s11269-008-9319-8

[15]   H. Baalousha, “Assessment of a Groundwater Quality Monitoring Network Using Vulnerability Mapping and Geostatistics: A Case Study from Heretaunga Plains, New Zealand,” Agricultural Water Management, Vol. 97, No. 2, 2010, pp. 240-246. doi:10.1016/j.agwat.2009.09.013

[16]   N. G. Tait, D. N. Lerner, J. W. N. Smith and S. A. Leharne, “Priorisation of Abstraction Boreholes at Risk from Chlorinated Solvent Contamination on the UK Permo-Triassic Sandstone Aquifer Using a GIS,” Science of the Total Environment, Vol. 319, No. 1, 2004, pp. 77-98. doi:10.1016/S0048-9697(03)00438-8

[17]   H. Huan, J. S. Wang and Y. Teng, “Assessment and Validation of Groundwater Vulnerability to Nitrate Based on a Modified DRASTIC Model: A Case Study in Jilin City of northeast China,” Science of the Total Environment, Vol. 440, 2012, pp. 14-23. doi:10.1016/j.scitotenv.2012.08.037

[18]   C. Güler, M. A. Kurt, M. Alpaslan and C. Akbulut, “Assessment of the Impact of Anthropogenic Activities on the Groundwater Hydrology and Chemistry in Tarsus coastal Plain (Mersin, SE Turkey) Using fuzzy Clustering, Multivariate Statistics and GIS Techniques,” Journal of Hydrology, Vol. 414-415, 2012, pp. 435-451.

[19]   UN-HABITAT, “The State of African Cities 2008: A Framework for Addressing Urban Challenges in Africa,” United Nations Human Settlements Programme, Nairobi, 2008.

[20]   K. Awosika, T. Akosa, B. Akanji, B. Daramola and G. Akpokodje, “State Report Lagos State,” In: N. Rao and R. Palmer-Jones, Eds., Gender and Growth Assessment— Nigeria, Department for International Development (DFID) and Canadian International Development Agency (CIDA) Report, Lagos, 2009, pp. 1-37.

[21]   P. Okunola, “Lagos under Stress,” Dossier Habitat Country Reports, Fiji, 1996.

[22]   I. O. Adelekan, “Vulnerability of Poor Urban Coastal Communities to Climate Change in Lagos, Nigeria,” 5th Urban Research Symposium, Marselles, 2009, pp. 1-18. http://siteresources.worldbank.org/INTURBANDEVELOPMENT/Resources/336387—1256566800920/6505269—1268260567624/Adelekan.pdf

[23]   Federal Department of Agricultural Land Resources (FDALR), “Reconnaissance Soil Survey of Nigeria,” FDALR, Lagos, 1995, p. 281.

[24]   BBC, “Weather BBC Weather Lagos Nigeria,” BBC, London, 2011.

[25]   ESRI, “ArcGIS Version 9.3. 380,” New York Street, Redlands, 2009.

[26]   J. Vrba and M. Civita, “Assessment of Gronudwater Vulnerability,” In: A. Zaporozec and J. Vrba, Eds., Guidebook on Mapping Groundwater Vulnerability, International Contributions to Hydrogeology, International Association of Hydrogeologists, Lingen, 1994, pp. 31-38.

[27]   O. O. Ojuri, S. A. Ola, D. L. Rudolph and J. F. Barker, “Contamination Potential of Tar Sand Exploitation in the Western Niger-Delta of Nigeria: Baseline Studies,” Bulletin of Engineering Geology and the Environment, Vol. 69, No. 1, 2010, pp. 119-128. doi:10.1007/s10064-009-0239-5

[28]   A. M. Gbadebo, “Assessment of Quality of Groundwater from Lagos Metropolis and Its Possible Health Implications,” In: J. Freid and J. Scherfig, Eds., Proceedings International Conference on Water Scarcity, Global Changes, and Groundwater Management Responses, The University of California, Irvine, 2008, pp. 905-910.

[29]   B. A. Adebo and A. A. Adetoyinbo, “Assessment of Groundwater quality in Unconsolidated Sedimentary Coastal Aquifer in Lagos State, Nigeria,” Scientific Research and Essay, Vol. 4, No. 4, 2009, pp. 314-319.

[30]   E. O. Longe and L. O. Enekwechi, “Investigation on Potential Groundwater Impacts and Influence of Local Hydrogeology on Natural Attenuation of Leachate at a Municipal Landfill,” International Journal of Environmental Science and Technology, Vol. 4, No. 1, pp. 133-140.

 
 
Top