Developing methodologies for sustainable groundwater management in sub-Saharan Africa: a case study of the Chad Basin around Maiduguri, Nigeria
This study developed sustainable groundwater management methodology applicable to sedimentary environments in sub-Saharan Africa, taking the Chad basin, Northeastern Nigeria as a case study. The study employed integrated methodological approaches and is divided into three major interrelated phases. The first phase of the study carried out a stakeholder analysis and identified the stakeholders that are responsible for and those affected by problems of groundwater contamination as well as those that have formal authority and influence in addressing the situation. A total of 22 stakeholder groups comprised of; 10 government agencies, 4 water user groups, 3 professional organisations, 3 civil society organisations, an NGO, and a research institution were identified and engaged at the tactical level via interviews, focus groups, and household surveys. The second phase evaluated the various above ground pollution sources and assessed their impact on groundwater, and carried out physico-chemical investigation of groundwater samples collected from selected shallow boreholes across the study area in determining the extent of contamination from the aforesaid pollution sources. The third phase of the study carried out modelling of chloride contamination due to pit latrine impacts and developed guidelines for mitigating the negative impact of on-site sanitation systems on the underlying aquifer. The results of the stakeholder engagement show that knowledge about groundwater contamination is good among the strategic stakeholders and limited among the primary stakeholders. Also, most interviewees are concerned about problems of contamination and are keen to be part of addressing the situation, a handful of focus group participants, and the survey respondents are equally concerned about this issue. Also, all the stakeholder categories suggested that community participation, increase in investment, controlling waste from source, and strict legislations are the possible ways of addressing the existing problems of groundwater management in the study area. Overall, social, economic, and cultural influences are the factors responsible for the prevalence of the pit latrines and open dumpsites. Risk matrix result shows that pit latrines, dumpsites, and other non-point sources are the potential sources of pollution based on the order of their magnitude. Geological material constitutes the lowest risks. Groundwater Physico-chemical analyses result show that the groundwater in the study area ranged from alkaline (pH 6.61-7.57) to slightly alkaline-acidic (6.2-7.31). The distribution of non-anthropogenic parameters such as; Na2+, Ca2+, K+ , and Mg2+ across all the boreholes varied significantly (p<0.05; significant level of 95% and confidence interval of 0.05). Also, the concentrations of anthropogenic indicator parameters such as; Cl- , NO3-, SO42- , and PO43- in the groundwater are correlated with the above ground pollution sources; their distribution across the boreholes of the study area varied significantly (p<0.05). Furthermore, the groundwater is currently of good quality for consumption. Equally, Granulometric and mineral content analyses of the sediment were carried out to determine the sediments particle sizes and the distribution of their contained minerals. Results show that the sediments particles ranged between 1mm-<63µm while minerals such as Quartz, Feldspar, Albite, Zircon and Iron Oxide are dominant. The alternative guidelines developed by this study can be applied across the major sedimentary basins of Nigeria. The study provides baseline data for achieving sustainable groundwater management in sub-Saharan Africa region. The concept outlined in this thesis can be replicated in other international case studies across Africa.
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