In assessing water security and forecasting the rate of groundwater recharge acts as a fundamental player (Gleeson et al, 2020). Groundwater can be found literally anywhere below ground, and it plays a vital role in making up the natural water cycle. Only 1% of Africa's agricultural area is irrigated using groundwater, indicating that the resource is underutilised (Sibert, et al, 2010). However, Africa is a continent with a rich resource of fresh groundwater, but it is being ignored. Through discovering this ‘gem’, Africa can make another huge step in reaching the 6th sustainable development goals (SDGs) by finding new freshwater resources.
Distribution of Groundwater in Africa
Groundwater in Africa is estimated to be 0.66 million km3 with a range of 0.36 to 1.75 million km3 (MacDonald et al, 2012), which is 100 times the annual renewable freshwater resources and 20 times the freshwater stored in Africa's lakes. Groundwater is Africa's largest and most widely scattered freshwater reservoir, acting as a key buffer against climate change and maintaining the continent's freshwater supply (MacDonald et al, 2009). The estimation of groundwater storage is conducted by combining the effective porosity and the saturated thickness of aquifers across the continent. It has been found that North Africa holds a considerable amount of groundwater, including countries such as Libya, Sudan and Egypt containing the largest reserves of groundwater (MacDonald et al, 2012). Although the Saharan aquifers are presently dryer, research has revealed that they were replenished around 5000 years ago when the environment was significantly wetter (Scanlon et al, 2006).
Africa's groundwater distribution +
Africa's geological base map for development of aquifer map -Source
Potential of Groundwater
As groundwater is stored beneath the ground, it is naturally protected from being contaminated by pathogens, which means the water is free from any post-treatment (Smedley, 1996, Edmunds and Smedley, 2005). The physical nature of rocks and minerals can also act as filters and purify the water, reducing the number of treatments of the water after extraction (Gaye and Tindimugaya, 2019). Moreover, groundwater can be discovered at most places under most environments, through using appropriate techniques for exploration, they can be easily located and extracted at the place of need, minimising the reticulation process of needing to transfer the water (MacDonald and Calow, 2009).
For places that suffer from unreliable rainfall, the use of groundwater can help in meeting rising demands for food production, irrigation and freshwater resources as the population grows (Pfister et al, 2011). This can reduce the risk of climate change having on food production, the use of groundwater can successfully increase the irrigation level of smallholder farmers to increase food production and strengthen food security.
Groundwater is also easily accessible through various methods, including boreholes and wells. For most populated areas in Africa, groundwater is shallow enough that it can be accessed by using head pumps (MacDonald et al, 2021). This would help rural areas that suffer from the lack of access to piped water, where they now can create their own freshwater source.
It is critical to recognise that groundwater must be extracted in a sustainable manner, as quick groundwater extraction in other parts of the world has resulted in substantial unsustainable conditions, such as groundwater contamination and declining water tables (Rodell et al, 2018). Therefore, governments should not solely rely on groundwater storage maps and aquifer permeability as they are insufficient in making effective decisions (Edmunds, 2012).
The existing maps only provide qualitative information on the expected extent of nationwide aquifers, but they do not provide quantitative information on the groundwater resources' actual dimensions (Struckmeier and Richts 2008). It is important to understand and fill this knowledge gap before deciding on appropriate strategies.
Furthermore, it is difficult to manage African groundwater resources in a way that minimises environmental deterioration due to a lack of awareness (Foster and Chilton, 2003). The substantial uncertainties of how climate change will influence groundwater supplies were also addressed in the IPCC Fourth Assessment Report and Technical Report on Water (Bates et al, 2008), making it difficult to decide on the best adaptation methods for Africa.
Really interesting read about groundwater stores as often Africa is painted as a continent where there is no water but having read this entry it is evident that there is plenty. I agree that the most important issue is how do these African countries go about extracting and distributing water sustainably.
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