Abstract
This paper characterizes the aquifer system of the Niger Delta for sustainable development of the groundwater resource. The heavy-dependence on groundwater in the region and the fears of its unsustainability triggered by the weak regulations, pollution, increasing user population and industrialization coupled with the present limited knowledge of the true geological condition prevailing within the groundwater domain of the Niger Delta are the considerations that compelled this review study. The hydraulic properties of the region’s aquifers are discussed. The Niger Delta is characterized by a complex multilayered aquifer system hosted in the Benin Formation with the main body of fresh water, with increasing occurrence of intercalating clay units towards the coast. Lithological analysis indicates the prevalence of unconsolidated sand and sandy gravels in the aquiferous horizons, presenting them as pervious and prolific aquifers. Reported hydrochemical data gathered from wells drilled suggest that the quality of groundwater in the Niger Delta is considered generally very good and compares favorably with WHO standards for drinking water. However, relatively high iron/manganese and chloride values are localized in time and space. In the coastal areas however, seawater intrusion has been identified as one of the major influences on hydrochemistry of groundwater in the shallow unconfined aquifers. Regional groundwater flow direction is from north to south. Changes in groundwater flow directions which occur at some places generally serve localized discharge areas. The resultant flow path eventually joins and feeds the major regional north-south flow direction. The increasing pressure on groundwater, the need for urgent attention and the absence of strong institutions and regulations have made the management of groundwater resources in the region a difficult task. Therefore, future ground water resources development in the Niger Delta requires adequate observational data, investments in infrastructure and an integrated management approach to ensure optimal basin-wide benefits.
Highlights
Most of the Niger Delta relies on groundwater for both domestic and industrial uses
Aquifers at the northern border of the Niger Delta are more continental in character, being composed of thicker and coarser river sand coming from the hinter land and characterized by much fewer clay intercalations as evidenced in a lithologic map of the Benin Formation drawn from borehole lithologs in the different zones (Figure 3)
The hydrogeology of the Niger delta is dominated by the Benin Formation, which serves as aquifer and facilitates recharge of groundwater in the region
Summary
Most of the Niger Delta relies on groundwater for both domestic and industrial uses. According to JICA (2014); there were around 65,000 boreholes in Nigeria extracting an estimated total of 6,340,000 m3/day in 2013. Before the 1970’s the major cities in the region were served by well planned, relatively deep boreholes whose water was widely reticulated to individual homes and factories. The unprecedented demand for freshwater associated with high population growth and increased living standards has resulted in highly elevated groundwater drilling activities, which is creating some concern over the sustainability of the resource for the future. The second motivating reason for this review study is that several previous studies of the groundwater in the region have been localized [4] [5] [6] [7] and do not offer comprehensive and holistic understanding of issues such as long-term quality and sustainability in the face of climate change and industrialization. There is no doubt that a better understanding of the regional hydrogeology is essential in the overall sustainable management of the region’s groundwater resources
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