(GIS) in Sustainable Groundwater Development, Imo River Basin Nigeria
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Vol. 5(6), pp. 310-320, June, 2013 International Journal of Water Resources and DOI 10.5897/IJWREE2012.0382 ISSN 2141-6613 © 2013 Academic Journals Environmental Engineering http://www.academicjournals.org/IJWREE Full Length Research Paper Application of Geographic Information System (GIS) in sustainable groundwater development, Imo River Basin Nigeria Michael A. Nwachukwu1*, Aslan Aslan2 and Maureen I. Nwachukwu3 1Department of Environmental Technology, Federal University of Technology Owerri Nigeria. 2Earth and Environmental Studies, Montclair State University New Jersey, U.S.A. 3Department of Geosciences, Federal University of Technology, Owerri Nigeria. Accepted 13 May, 2013 There is proliferation of shallow substandard private water wells, poor distribution of public water wells, poor planning, and poor management of public wells in the Imo River basin Nigeria. Over 60% of water wells developed in the basin is either abortive or not functional. To investigate this, 110 vertical electric soundings (VES), 50 down-hole logs, and 44 pumping test data have been integrated into geographic information system (GIS) in this study. Map of 44 county areas of the basin was produced. Thematic maps showing mean values of water table, aquifer resistivity, aquifer thickness, and a groundwater prospect map of the basin in five potential areas were also produced. Correlating the GIS map with regional geologic map defined three groundwater prospect zones in the basin. Sustainable practices recommended are government-private partnership for public wells, and private-private partnership for private wells. Surface water development is recommended in zone 3, against groundwater development. Geophysics/GIS groundwater prospect model shows significant correlation with geology, confirming the effects of geology to groundwater development in the basin. Key words: Private/Public water wells, geophysics data, geographic information system (GIS) models, abortive wells, geology, sustainability. INTRODUCTION Unavailability of groundwater prospect map of the basin 850 in the basin. It is therefore very necessary to do area for public consumption is thought to have everything possible that can reduce incidents of abortive contributed greatly to the increasing failure of water well wells, substandard domestic wells, and non-functional projects in certain parts of the Imo River basin Nigeria wells. With good groundwater prospect map, government (Figure 1a and 1b). For example, groundwater prospect would award contracts of water well projects to only map is a vital tool to government in water well allocation viable areas, excluding areas where difficult subsurface decision making process. By this, individuals, geology does not allow successful groundwater organizations, communities, and governments could development. Groundwater prospect map will allow fair visualize areas mapped as difficult for groundwater distribution of public water wells to communities. development and then be committed to an alternative Groundwater prospect map will reduce economic wastes, water sources in such areas. This will reduce incidents of and environmental degradation, as well as disappoint- failure, abortive, or abandoned public wells and non- ment and hardship to the affected communities; based on functionality of domestic water wells estimated at over a model of distribution with no consideration for areas with *Corresponding author. E-mail: [email protected]. Tel: +23408163308776. Nwachukwu et al. 311 Figure 1. Map of Nigeria showing Imo River basin. groundwater development difficulty. more vulnerable to pollution than the equivalent in the The result is economic waste, and environmental north. degradation, as well as greater disappointment to the affected communities. Citizens are therefore constrained to the proliferation of shallow substandard wells often Geology recharged by surface water through fractures, and harvested rain water stored in ground tanks of all The basin is a 140 km N-S trending sedimentary syncline manners. This may be accountable to the persistence of located at the mid south-eastern part of Nigeria (Figure water related diseases in the basin. 1). It is rich in oil and gas and has many of Nigerian oil Proliferation of shallow private/commercial wells of poor fields. The basin has rich deposit of clay minerals, sand, standards by individuals also implies financial incapability gravel, and lignite. Based on near surface lithology, the for standard wells. This is due to lack of functional public Imo River Basin was divided into two zones (Nwachukwu water supply, and the excessive desire of citizens to be et al., 2010a). The northern zone consisting of group of self dependent. The most contaminated wells are usually shale formations have greater drainage density, than the the shallow hand-dug rather than drilled, and having poor southern zone belonging to the sandy Benin Formation casing material (Comely, 1987). Incidentally most of the (Figure 10). Age of the shaly zone range from paleocene shallow private and commercial wells in the basin are to Albian, and the sandy zone is Olgocene to Recent. hand-driven, and some constructed with inferior casings. Prospective horizon for groundwater development in the According to Nwachukwu et al. (2010b), the greatest basin varies from location to location. Age and problem of manual drilling is the impunity at which the characteristics of the geologic units are discussed by operators declare the drilling terminated, soon as the Reyment (1965), Onyeagocha (1980), and Ekweozor and crew penetrates the water table, or run out of energy. Ibe Unomah (1990). et al. (2007), Nwachukwu et al. (2010a), and Nwachukwu Recent investigation confirmed the presence of 40 to et al. (2010c), have confirmed that environmental 70 counts of coliform per 100 ml of water in six out of ten pollution in the Imo River basin increases from the shaly sampled shallow wells around Owerri (Nwachukwu et al., north to the sandy south. They hold that human activities 2010b). This may have significant health implications. also follow a similar trend, representing the primary The average cost of treating severe typhoid fever and source of water pollution in the Imo River basin. The final diarrhea (alias stooling and vomiting) to families which analysis implicates shallow wells in the sandy south to be may result in sudden deaths is enormous. It is a major 312 Int. J. Water Res. Environ. Eng. source of poverty, draining both the household and the decision support tool. Water table maps are used to state economy. The overall effects, including the loss of estimate ground water flow direction and velocity; man hour in both public and private sectors is alarming, vulnerability assessments or pollution transport. It is and difficult to be estimated due to lack of records. A commonly used in environmental decision making such recent survey has confirmed the presence of one or two as locating landfills and wastewater disposal sites. The abortive wells in the vicinity of three to five functional well creation of water table maps is a well accepted practice in the area. Most of the private and public wells became in ground water investigations. Jasrotia and Singh (2005) abortive immediately on completion. Others became non- used water table thematic layers and other parameters functional 2 to 5 years after completion, or abandoned integrated through the DRASTIC model within a GIS during construction. If this situation continues unchecked, environment to demarcate vulnerable zones of a the basin may encounter a more serious disaster with watershed. quality of water resources, well interference and loss of space or reservation for future groundwater development. Singh and Prakash (2004) integrated thematic maps Vulnerability of water table aquifer south of the basin through GIS for identification of groundwater potential area zones. Kamaleshwar et al. (2000) integrated some physical parameters and terrain characteristics with GIS Figures 2 and 3 largely show contaminant transport to the and remote sensing to extract groundwater prospect southeast after (Nwachukwu et al. (2010c). The zone in Dala-Renukoot area of Uttar Pradesh, India. They southward Otamiri River flow, and groundwater flow arrived at five groundwater prospect categories. Kumar et facilitates this transport (Figure 2). South-southeast al. (2010) has delineated groundwater potential zones tracking and capture zone of contaminants (Figure 3) using remote sensing and GIS techniques in Kurmapalli suggest greater groundwater pollution. Groundwater flow, Vagu basin, India. They emphasized that systematic and contaminant transport is reduced in the south-end planning of groundwater development using modern portion of the area with horizontal and vertical flows at the techniques is essential for the proper utilization and swamp (Figure 2b). There is indiscriminate dumping of management of this precious but shrinking natural solid waste, and disposal of urban sewage on farm land resource. Similarly, they obtained five categories of as fertilizer farm input. This habit increases bioavailability groundwater potential zones ranging from very good to of trace metals and other contaminants in the southern poor in the basin. portion of the basin. Shallow water table in the south west In this study, surface and borehole electrical resistivity flank of the basin enhances contaminant transport and and SP, and pumping data are integrated in GIS to map pollution of the water table \aquifer in the basin area.