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New research suggests groundwater in Africa could be resilient to climate change
Flooding in Tanzania (image courtesy of Gro Futures)
Groundwater – a vital source of water for drinking and irrigation across sub-Saharan Africa – may be relatively resilient to climate variability and change, according to a new study involving the University of Sussex.
Groundwater, water present beneath the Earth's surface, plays a central role in sustaining water supplies and livelihoods in sub-Saharan Africa due to its widespread availability, generally high quality, and intrinsic ability to buffer episodes of drought and increasing climate variability.
Climate change has put increased pressure on water resources, but whilst it was known that surface water was likely to be badly affected by climate change in many regions, much less was known about the impacts on groundwater.
In a paper published today in Nature, researchers have shown how groundwater replenishment depends upon heavy rainfalls and flood events, which may be amplified by climate change.
The findings could provide a sustainable ‘climate proof’ way to provide enough water for a growing population, helping tackle several of the UN’s Sustainable Development Goals in the process.
Martin Todd, Professor in Climate Change at the University of Sussex and co-author of the paper said: “Access to safe, clean water remains a problem for many in Africa. At the same time, the demand for water is increasing rapidly as African economies and populations grow.
“Groundwater can offer a pathway for sustainable freshwater resource development to meet these needs for agricultural irrigation and domestic supplies.”
Dr Mohammad Shamsudduha, a Lecturer in Physical Geography (Water) at the University of Sussex and co-author, described groundwater as a 'hidden resource' that countries should begin to use.
He said: "Groundwater can be deep and it's expensive to extract. But cities can use it more strategically as a climate-resilient resource in cases of emergency and in the event of climate shocks such as droughts."
The research, supported by various UK research councils including NERC, ESRC and EPSRC as well as the Department for International Development (DFID), involved a consortium of 32 scientists from across Africa and beyond.
Collating long-term records of groundwater levels and rainfall across Africa, they investigated how variations in climate across differing geological settings impacted the replenishment of groundwater.
The findings show, for the first time, how climate plays a dominant role in controlling how groundwater is restocked.
In humid areas groundwater is replenished primarily by rainfall that directly infiltrates the land surface, whereas in drylands it occurs predominantly by leakage from temporary streams and ponds.
Dr Mark Cuthbert, Research Fellow and Lecturer at Cardiff University and co-lead on the study, said: “Previous regional-level assessments of groundwater resources using large-scale models have ignored the contribution of leaking streams and ponds to groundwater supplies, underestimating its renewability in drylands.”
The extreme heavy rainfalls and flood events generating this groundwater replenishment are commonly associated with climate variations including global-scale El Niño and La Niña events.
Professor Todd said: “With this improved understanding we are now in a position to develop much more reliable projections of the impact of climate change on groundwater, which has previously been over-simplified.
“The dependence of dryland groundwater on climate extremes may actually mean groundwater is more resilient to climate change than previously believed, unlike surface water in these regions.
“Strategies and plans for ‘climate resilient development’ in Africa including climate-proofed water resource development plans will now be better informed.”
The research was part of the Sussex Sustainability Research Programme (SSRP), which aims to provide science for the tackling of the Sustainable Development Goals (SDGs).
Professor Joseph Alcamo, Director of SSRP said: “This paper shows the important knowledge academics can contribute towards the Sustainable Development Goals.
“Many people in the policy and science communities are hoping that the groundwater supply in Africa can be used to boost irrigation and help achieve Goal 2 (zero hunger), as well as provide the clean water for all promised in Goal 6, and help adapt to climate change, as spelled out in Goal 13.
“In this paper Martin Todd and his other colleagues have provided the facts and figures we need to find out whether groundwater can indeed fulfil its promise.”