Assess the potential for aquifers to contribute to Africa’s water supply

The potential for aquifer use varies distinctly across Africa due to differences in the quantity and recharge rate and depth of aquifers. In Saharan Africa (in particular Algeria, Libya, Egypt, Chad) the groundwater storage of the aquifers is very high with the majority being over 50,000mm deep (50 metres). The aquifer productivity is also high with the majority of the region at 5-20 litres per second. At first look this makes aquifers a very attractive potential water source however the region suffers from low recharge rates due to the rarity of rainfall in the Saharan desert. This means that whilst aquifers could provide a temporary solution to drought in Saharan Africa it would not be sustainable.

In equatorial regions groundwater storage is also relatively high with aquifers under the Democratic Republic of Congo, Zambia, Angola and Botswana holding significant quantities of water (between 10-25 and 25-50 metres deep). The aquifers are also quite close to the surface in comparison to Saharan Africa, typically only 7-25 metres. The recharge rate is also extremely high with over 100 mm/year across most of the nations aside from Botswana which only experiences around 5-25 mm/year. The productivity of the aquifers is also promising with the majority being high (5-20 litres/second). However the high recharge rate is due to the large amounts of rainfall the region experiences due to its proximity to the equator. This means that there is no real need for aquifers as the area does not often experience drought to any severe degree.

In Eastern Africa (in particular Somalia, Ethiopia and Kenya) groundwater storage is high, with around 25-50 metres depth. However the aquifers are extremely deep, between 100-250 metres deep in the coastal areas and 50-100 metres deep inland, meaning it would be extremely expensive to tap into the aquifers on a large scale. The productivity of the aquifers is also low, with a discharge rate of only 0.5-1 litres per second in the majority of the area. This means that whilst there is a significant amount of water available in the aquifers it would be too costly to extract for such low output. A similar story is true in North-Western Africa (in particular Mali, Mauritania, Sengal, Gambia, Guinea, Guinea Bissau) whereby there is a lot of water stored however productivity is too low where the aquifers are not far underground and where productivity is high the aquifers are typically too deep.