UPGro Science: No substantial decline in the volume of water stored in the major aquifer basins over the last 15 years, but there are major localised risk areas [S6]

At the scale of the African continent, UPGro research has shown that there has been no substantial decline in the volume of water stored in the major aquifer basins over the last 15 years. However, local contexts do differ, and in some African cities, groundwater levels have fallen.

This is already evident in some urban centres such as Addis Ababa, Ethiopia, which relies on groundwater for more than 60% of its water supply. Monitoring by UPGro researchers is showing a general decline in groundwater levels, which is rapid in some areas. Large abstractors are drilling deeper – in some cases >500m – to secure supplies, but this has implications for smaller-scale groundwater users.  Many wells and boreholes – often community boreholes equipped with handpumps – that access the shallow volcanic aquifers are being abandoned due to declining groundwater levels, with implications for domestic water supply in the city.

Groundwater resource modelling in growing cities, such as Dodoma and Arusha in Tanzania, also indicate that increased groundwater demand due to population growth will be unsustainable, resulting in rapid depletion of groundwater storage by 2050 (to be published). This requires development and enforcement of policy that controls groundwater use to balance abstraction demands with source and resource protection and recharge. Adaptation measures such as Managed Aquifer Recharge (MAR) may be appropriate in certain hydrogeological environments to increase groundwater storage, as is being explored at the Makutapora Wellfield – the main water supply for Dodoma.

Islands, such as the Comoros, and coastal areas are at particular risk because the limited renewable fresh groundwater resources are under pressure from growing demands, and from degradation because of human activity.

References and further information

1. Taylor, et al. (2019). Topical Collection: Determining groundwater sustainability from long-term piezometry in Sub-Saharan Africa  Hydrogeol J
2. Bonsor, et al (2018). Seasonal and Decadal Groundwater Changes in African Sedimentary Aquifers Estimated Using GRACE Products and LSMs. Remote Sens. .
3. Foster S et al (2018).; Urban groundwater use in Tropical Africa – a key factor in enhancing water security?. Water Policy
4. Shamsudduha M., et al (2017) Recent changes in terrestrial water storage in the Upper Nile Basin: an evaluation of commonly used gridded GRACE products, HESS
5. Comte, et al (2016), ‘Challenges in groundwater resource management in coastal aquifers of East Africa: Investigations and lessons learnt in the Comoros Islands, Kenya and Tanzania’. Journal of Hydrology: Regional Studies.

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