Groundwater recharge in Africa: identifying critical thresholds

The development of groundwater for safe drinking water, irrigation and other uses offers huge potential for improving the lives of many African people. Recent research showed that groundwater was present in most parts of Africa and represented a resource greater than the water available in lakes and rivers. However, a key uncertainty is how sustainable groundwater abstraction will be: is it being replenished and if so by how much and will this change in the future?

This research project will bring together a team of African, European and US scientists to examine all the available evidence for groundwater recharge across Africa. The team will use these data to search for the existence of critical recharge thresholds: conditions beyond which recharge may not occur or become unreliable. They will use the datset to develop a map of observed groundater recharge volumes for Africa and look for systematic changes across the continent. The team will also use the opportunity to examine the different methods for measuring groundwater recharge and identify the most appropriate for African conditions.

Together with social scientists they will use the results of the research to highlight areas and future scenarios where groundwater recharge may become a major contraint on sustainable groundwater abstraction, and where wells or boreholes may run dry, impacting particularly on the rural poor. The maps of groundwater recharge, and the quantification of critical thresholds can have many different uses: they should help quantify the risks of groundwater development and manage tradeoffs in abstraction for the benefit of the poor; for water engineers working in Africa, they should allow a first pass assessment of groundwater recharge to screen whether recharge may be a major constraint on a project, and also provide the tools for measuring recharge more accurately; for the academic community these new datasets can be used to validate global or continetal scale land surface hydrological models. Once the research is completed a workshop and webinar convened by WaterAid will help explore the implications of the research results for planning and implementing new water projects in Africa.

The results of this research will be used as a springboard to design a large field programme of interdisciplinary research to examine the processes which lead to these critical recharge thresholds to allow much more reliable forecasts of where groundwater development may become unsustainable in the future and to explore how groundwater can be best managed in these critical areas.

The results of this research have the potential to have a significant and widespread impact, which ultimately should lead to the sustainable development and management of groundwater for the poorest within Africa. A strategy has been developed to help the research influence water policy in Africa, be taken up by water practitioners and professionals and be used by the wider academic community for other uses, such as validating global models (see the pathwway to impact attachment). The research will also help build capacity within African research community.

Ultimate beneficiaries of the research
Many of the improved water services in Africa rely on groundwater, and efforts to supply 344 million without access to secure water services will also largely depend on groundwater. Sustainable groundwater development has the potential to contribute to reducing poverty across Africa by providing secure drinking water supplies for all, particularly the poor who have little alternative. However, for groundwater development to continue to provide benefits for the poor it needs to be regularly recharged by rainfall. This research will provide information and data on how groundwater recharge varies across the continent and what critical thresholds exist which could significantly alter recharge volumes and timing. Therefore, with increasing abstractions of groundwater forecast for both domestic and agricultural uses, this research has the potential to provide quantitative information to help make informed decisions on how to manage tradeoffs in abstraction for the benefit of the poorest.

Research users
The research outputs will be in various forms to make them accessible to different stakeholders. For example the research will produce a policy brief jointly with ODI, develop easily understood maps, and hold workshops and webinars as well as publish a high impact paper and accompanying dataset.

Policy makers, such as DFID, World Bank, Gates Foundation, individual water ministries should benefit from this research by having a first estimate of groundwater recharge for different parts of Africa and information on the potential significance of crossing critical thresholds.

Practitioners (e.g. UNICEF, WaterAid, country water departments, water engineers and hydrogeologists) will benefit from the research by having a first estimate of potential recharge, and a methodology for how to assess recharge for their project areas. Also by examining critical thresholds and future climate scenarios it will allow practitioners to assess potential longterm vulnerabilities in water supply services.

The academic community will also benefit from this research, providing a spring board for future work and also a benchmark data set and review to help validate global or continental models. The research will lead to a major publication and the accompanying data will be made freely available. The research results are likely to be of interest to the global water modelling community by providing data against which their models can be validated. The research will also be of use to a wide range of disciplines by giving some estimate of the sustainability of groundwater abstraction for Africa.

Capacity Building. The project provides a significant opportunity to build capacity in the African groundwater research community. The four African researchers rarely, if ever get the opportunity to meet or work together, and this research gives the platform for this to occur. It will also foster links between the French and English speaking African research communities and build bridges between US and UK researchers.