Urban groundwater quality in sub-Saharan Africa: current status and implications for water security and public health

Groundwater resources are important sources of drinking water in Africa, and they are hugely important in sustaining urban livelihoods and supporting a diverse range of commercial and agricultural activities. Groundwater has an important role in improving health in sub-Saharan Africa (SSA). An estimated 250 million people (40% of the total) live in urban centres across SSA. SSA has experienced a rapid expansion in urban populations since the 1950s, with increased population densities as well as expanding geographical coverage. Estimates suggest that the urban population in SSA will double between 2000 and 2030. The quality status of shallow urban groundwater resources is often very poor due to inadequate waste management and source protection, and poses a significant health risk to users, while deeper borehole sources often provide an important source of good quality drinking water. Given the growth in future demand from this finite resource, as well as potential changes in future climate in this region, a detailed understanding of both water quantity and quality is required to use this resource sustainably. This paper provides a comprehensive assessment of the water quality status, both microbial and chemical, of urban groundwater in SSA across a range of hydrogeological terrains and different groundwater point types. Lower storage basement terrains, which underlie a significant proportion of urban centres in SSA, are particularly vulnerable to contamination. The relationship between mean nitrate concentration and intrinsic aquifer pollution risk is assessed for urban centres across SSA. Current knowledge gaps are identified and future research needs highlighted

Urban groundwater quality in sub-Saharan Africa: current status and implications for water security and public health

Groundwater resources are important sources of drinking water in Africa, and they are hugely important in sustaining urban livelihoods and supporting a diverse range of commercial and agricultural activities. Groundwater has an important role in improving health in sub-Saharan Africa (SSA). An estimated 250 million people (40% of the total) live in urban centres across SSA. SSA has experienced a rapid expansion in urban populations since the 1950s, with increased population densities as well as expanding geographical coverage. Estimates suggest that the urban population in SSA will double between 2000 and 2030. The quality status of shallow urban groundwater resources is often very poor due to inadequate waste management and source protection, and poses a significant health risk to users, while deeper borehole sources often provide an important source of good quality drinking water. Given the growth in future demand from this finite resource, as well as potential changes in future climate in this region, a detailed understanding of both water quantity and quality is required to use this resource sustainably. This paper provides a comprehensive assessment of the water quality status, both microbial and chemical, of urban groundwater in SSA across a range of hydrogeological terrains and different groundwater point types. Lower storage basement terrains, which underlie a significant proportion of urban centres in SSA, are particularly vulnerable to contamination. The relationship between mean nitrate concentration and intrinsic aquifer pollution risk is assessed for urban centres across SSA. Current knowledge gaps are identified and future research needs highlighted

A review of urban groundwater use and water quality challenges in Sub-Saharan Africa

Large parts of Sub-Saharan Africa (SSA) are experiencing rapid urban population growth. Current projections estimate that by 2030 half the population of SSA will be living in urban areas, and if current trends persist half of these people will reside in slums. According to UN-Habitat, access to safe drinking water for slum dwellers is a major priority (UN-Habitat, 2003). Because of the lack of services, self-provision of water, using groundwater sources, is widespread in slums and is likely to increase as the urban centres expand, putting pressure on the quality and quantity of the groundwater resource. Over the last three decades there has been a concerted effort to increase access to improved water supply and sanitation across Africa. Within urban, and peri-urban, settings this has led to widespread development of groundwater resources for domestic water supply, mainly through growth in the private groundwater supply sector, and the proliferation of on-site sanitation, largely through the use of pit latrines. Due to the high population densities, latrines are often constructed in very close proximity to wells and springs used for drinking water, and can be a significant source of contamination. The lack of adequate management of household and industrial waste in many urban centres is also a growing concern. This has led to the groundwater resources being put under considerable stress in terms of water quality and in some cases water availability. The parallel deterioration of the water quality and availability in urban areas in SSA and increases in demand challenge the sustainability of the current situation. This has occurred over the last three decades for most urban centres in SSA (Foster et al., 1996). While there is not the very long historical legacy of urban pollution in many urban centres in SSA, in contrast with Europe and Asia for example, the problem of long term pollutant loading to groundwater is now becoming a reality. There is currently a limited evidence base of groundwater quality studies in urban centres across SSA with which to inform long term policy on the development of urban and peri-urban groundwater resources. This document provides an overview of urban and peri-urban drinking water and sanitation in SSA as well as urban groundwater development and degradation. The review draws on published and grey literature from across SSA and is both a useful entry point for researchers in this area and is a baseline reference work on the topic of urban groundwater quality in SSA. Detailed case studies from West Africa (Ibadan, Nigeria) and Southern Africa (Lusaka, Zambia) are included in this document. It provides: i) a detailed review of empirical studies assessing groundwater degradation (chemical and microbiological) in urban groundwater across SSA, ii) assesses urban groundwater quality issues in relation to groundwater vulnerability and hydrogeological controls, iii) identifies gaps in the current evidence base regarding groundwater quality and risks to groundwater pollution and human health in urban SSA

Resilience in groundwater supply systems: integrating resource based approaches with agency, behaviour and choice

Access to safe and reliable water supplies is a key goal for households and governments across most of Africa. Groundwater reserves can play a critical role in achieving this, yet risks of contamination and over-abstraction threaten to undermine the resilience of this supply. A rapidly rising trend for privately-developed wells and boreholes raises additional concerns about the vulnerability of water supplies to natural or man-made environmental shocks. The potential scale of the situation is particularly marked in Nigeria where the use of boreholes has increased exponentially since 1999 (from 10% of the population to 38% in 2015), with most other forms of water supply, notably piped tap water, falling. Developing effective groundwater management approaches that build the resilience of communities is challenging, not least given the range of different actors involved, their competing interests and demands, and variations in the hydrogeological environment. Insights from resilience studies in social science emphasise how the resilience of ecological resources to shocks and change is critically linked to the adaptive capacity of social systems and their agents. Choices made now have long-lasting effects, yet these choices are little understood. Understanding the choices made by consumers, drillers and policy actors requires a strong interdisciplinary dimension and argues for new perspectives as to how the resilience of communities and societies might be built. The project brings together a unique interdisciplinary collaboration between academics from the UK and Nigeria working in the fields of economic geography, psychology, hydrogeology and journalism studies

Preliminary results from a Water Economy and Livelihoods Survey (WELS) in Nigeria and Mali, sub-Saharan Africa : investigating water security across a rainfall transect

A large proportion (47%) of people in sub-Saharan Africa live without access to safe water sources in rural areas (JMP, 2008). The need for sustainable development and management of water resources, particularly groundwater resources, remains a major priority, especially within the context of climate variability, population growth and pressures to increase food production (UN, 2000, Vörösmarty et al., 2000, JMP, 2008, MacDonald and Calow, 2010). In stark contrast to food scarcity, to date little systematic data collection has been done to investigate the role water scarcity has on livelihoods within rural communities in sub-Saharan Africa, particularly during droughts or periods of water stress (Calow et al., 2009). A water, livelihoods and economy survey in West Africa was conducted as part of a one year DFID-funded research programme, aimed at improving understanding of the impacts of climate change on groundwater resources and local livelihoods http://www.bgs.ac.uk/GWResilience/. The main purpose of this survey was to investigate the access to and domestic use of a range of water sources (hand pumps, wells, springs, surface water sources and rainwater harvesting) within rural communities across a rainfall transect in sub-Saharan Africa. The seasonal water use and scarcity/stress patterns were investigated for rural communities, located on both sedimentary and basement settings, using community discussions and questionnaires based on a scaled down version of the WELS methodology (Coulter, 2010). Plate 1 shows a WEL survey being carried out in the Minna study area, central Nigeria. The aim of this study is to investigate seasonal access to water supplies, by gathering information on the time taken to collect water, the different sources available at different times of year (wet and dry season) and the geological and hydrogeological conditions at each community. The hypothesis is that having a greater number of groundwater dependent water supplies in a community increases overall security of water access and reduces the time taken to collect water in the dry season. A secondary aim was to test whether a slimmed down WELS methodology based on that described by Coulter and Calow (2011) can be effectively applied to give useful information

Hydrochemical characteristics and quality assessment of groundwater from shallow wells in Gboloko Area, central Nigeria

Physiochemical assessment of shallow groundwater in Gboloko area was carried out  to determine its suitability for drinking and irrigation purposes. Eighteen (18)  groundwater samples were collected from different rural communities’ wells and  subjected field measurements of physical parameters followed by chemical analyses using ICP-MS, ICP-ES, Calorimetry and Turbimetry methods. The results show that pH of the groundwater ranged from 5.1 to 8.6 (mean 6.6) which indicates the  groundwater is slightly acidic and slightly alkaline. EC and TDS varied from 60  to1367mg/L (mean 277.4mg/L) and 53 to 995mg/L (mean 206.5mg/L) respectively. The concentration of major cations were in the order of Ca2+>Na+> Mg2+> K+ while that of anion were in the order of HCO3 ->Cl-> SO4 -> NO3- .Five hydrochemical facies were delineated from Piper plot; they are CaHCO3,  CaNaHCO3, CaMgCl, CaCl, and NaHCO3 water type. CaHCO3 water is the dominant facies which represents water of recharge zone while CaNaHCO3 and CaCl are the least. The presence of NaHCO3 CaNaHCO3, and CaMgCl water type shows  hydrochemical processes such as ion exchange and linear mixing. The drinking water quality assessment indicates the values for all the hydrochemical parameters are within the maximum permissible standard by WHO, 2006 except for two locations where nitrate concentrations are above the guideline value. The nitrate contamination observed at those locations may be attributed to leachates from domestic wastes and agricultural activities. Although nitrate contamination was expected to be rampant in  groundwater of the area Irrigation water quality indices showed that the groundwater is ranged from mostly suitable to unsuitable.Key words: Groundwater quality, Gboloko, Hydrochemical Facies, Irrigation wate