Potential impact of climate change on improved and unimproved water supplies in Africa

With significant climate change predicted in Africa over the next century, this chapter explores a key question: how will rural water supplies in Africa be affected? Approximately 550 million people in Africa live in rural communities and are reliant on water resources within walking distance of their community for drinking water. Less than half have access to improved sources (generally large diameter wells, springs, or boreholes equipped with handpumps); the majority rely on unimproved sources, such as open water and shallow wells. Major climate modelling uncertainties, combined with rapid socio-economic change, make predicting the future state of African water resources difficult; an appropriate response to climate change is to assume much greater uncertainty in climate and intensification of past climate variability. Based on this assumption the following should be considered: 1. Those relying on unimproved water sources (300 million in rural Africa) are likely to be most affected by climate change because unimproved sources often use highly vulnerable water resources. 2. Improved rural water supplies in Africa are overwhelmingly dependent on groundwater, due to the unreliability of other sources. 3. Climate change is unlikely to lead to continent-wide failure of improved rural water sources that access deeper groundwater (generally over 20 metres below ground surface) through boreholes or deep wells. This is because groundwater-based domestic supply requires little recharge, and the groundwater resources at depth will generally be of sufficient storage capacity to remain a secure water resource. However, a significant minority of people could be affected if the frequency and length of drought increases – particularly those in areas with limited groundwater storage. 4. In most areas, the key determinants of water security will continue to be driven by access to water rather than absolute water availability. Extending access, and ensuring that targeting and technology decisions are informed by an understanding of groundwater conditions, will become increasingly important. 5. Accelerating groundwater development for irrigation could increase food production, raise farm incomes and reduce overall vulnerability. However, ad hoc development could threaten domestic supplies and, in some areas, lead to groundwater depletion. Although climate change will undoubtedly be important in determining future water security, other drivers (such as population growth and rising food demands) are likely to provide greater pressure on rural water supplies

Household water use, poverty and seasonality: Wealth effects, labour constraints, and minimal consumption in Ethiopia

Data from a highland to lowland transect in the Oromia Region of eastern Ethiopia show that household water use is minimal, regardless of presence of improved sources, and variations in use are driven by interactions of poverty and rainfall variability. In the dry season, when many sources fail, use for hygiene drops perilously, particularly among poor households, as collection times rise and coincide with high demands for wage labour. Providing sufficient water for livestock is also a struggle for poor agropastoral households. Poorer households use less water because they have less labour for water collection and fewer storage and transport assets. Labour shortages also make nearer, unsafe sources preferable to more distant protected schemes. The health and livelihood benefits of improved water access depend on continuous use of sufficient safe water, by all, but we have limited knowledge of actual water use patterns. This paper aims to help address this gap, and documents intra-community inequities and seasonal variations in water access. These are not captured in coverage statistics, but are likely to occur wherever pronounced climate ariability, inadequate infrastructure and severe poverty coincide

What impact will climate change have on rural groundwater supplies in Africa?

One of the key uncertainties surrounding the impacts of climate change in Africa is the effect on the sustainability of rural water supplies. Many of these water supplies abstract from shallow groundwater (<50 m) and are the sole source of safe drinking water for rural populations. Analysis of existing rainfall and recharge studies suggests that climate change is unlikely to lead to widespread catastrophic failure of improved rural groundwater supplies. These require only 10 mm of recharge annually per year to support a hand pump, which should still be achievable for much of the continent, although up to 90 million people may be affected in marginal groundwater recharge areas (200–500 mm annual rainfall). Lessons learnt from groundwater source behaviour during recent droughts, substantiated by groundwater modelling, indicate that increased demand on dispersed water points, as shallow unimproved sources progressively fail, poses a much greater risk of individual source failure than regional resource depletion. Low yielding sources in poor aquifers are most at risk. Predicted increased rainfall intensity may also increase the risk of contamination of very shallow groundwater. Looking to the future, an increase in major groundwater-based irrigation systems, as food prices rise and surface water becomes more unreliable, may threaten long-term sustainability as competition for groundwater increases. To help prepare for increased climate variability, it is essential to understand the balance between water availability, access to water, and use/demand. In practice, this means increasing access to secure domestic water, understanding and mapping renewable and non-renewable groundwater resources, promoting small-scale irrigation and widening the scope of early warning systems and mapping to include access to water

The water poverty index: development and application at the community scale

The article details the development and uses of the water poverty index (WPI). The index was developed as a holistic tool to measure water stress at the household and community levels, designed to aid national decision makers, at community and central government level, as well as donor agencies, to determine priority needs for interventions in the water sector. The index combines into a single number a cluster of data directly and indirectly relevant to water stress. Subcomponents of the index include measures of: access to water; water quantity, quality and variability; water uses (domestic, food, productive purposes); capacity for water management; and environmental aspects. The WPI methodology was developed through pilot projects in South Africa, Tanzania and Sri Lanka and involved intensive participation and consultation with all stakeholders, including water users, politicians, water sector professionals, aid agency personnel and others. The article discusses approaches for the further implementation of the water poverty index, including the possibilities of acquiring the necessary data through existing national surveys or by establishing interdisciplinary water modules in school curricula. The article argues that the WPI fills the need for a simple, open and transparent tool, one that will appeal to politicians and decision makers, and at the same time can empower poor people to participate in the better targeting of water sector interventions and development budgets in general

Snails have stronger indirect positive effects on submerged macrophyte growth attributes than zooplankton

Phytoplankton and epiphyton often compete with submerged macrophytes. Grazing by zooplankton and/or epiphyton grazers should promote an indirect positive effect on submerged macrophyte growth rate. Hence, we mimicked shallow lakes conditions in mesocosms using a factorial design to evaluate the indirect effects of no grazers, zooplankton, snails or both grazers on macrophyte growth attributes. After 16 weeks, both snails and zooplankton had positive effects on macrophyte stem length and biomass. However, only snails had positive effects on macrophyte number of sprouts and root biomass. In addition, the positive effect size of snails on the submerged macrophytes was twice as large as the effect size of the zooplankton. Our study suggests that benthic food chains might be more capable of increasing resilience and affecting the stability of the clear-water state in shallow lakes than pelagic food chains. However, long-term experiments with varying relative proportions of herbivores and different macrophyte species, as well as in situ experiments, will be necessary to test the generality of our findings. Understanding the relative effects of benthic versus pelagic grazers on submerged macrophytes may increase the success of shallow lake restoration and should be taken into account when designing management and restoration efforts for shallow lake systems