UPGro researchers investigated the age of groundwater. They also looked at historical groundwater level and rainfall data. They found that in wetter areas recharge happens every year, but in dryland areas substantial recharge less regularly, often just once or twice a decade.
In arid and some semi-arid environments, groundwater stores are replenished episodically in response to extreme rainfall events. Such events may become more common under climate change and are often related to predictable climate phenomena. In these environments, focused groundwater recharge processes are often more important than diffuse recharge processes. During wet periods, in favourable hydrogeological environments, focused recharge can be enhanced to make full use of groundwater storage through managed aquifer recharge (MAR).
One MAR technique piloted through UPGro was rethinking and redesigning road drainage in northern Ethiopia. Diverting road runoff into infiltration ponds reduced soil erosion and increased groundwater recharge. The techniques have since been scaling-up across Ethiopia and assessed or introduced in Kenya, Uganda, Tanzania, Malawi, Zambia, Mozambique, Bangladesh, Nepal, Tajikistan, Pakistan and Bolivia.
Land cover also significantly influences recharge: in Ghana and Burkina Faso, recharge was found to be as much as 8 times greater on land under sorghum cultivation than that of grazed land, and also much higher than land with groundnut crops.
Continuous and strategic groundwater monitoring can build an understanding of groundwater recharge processes and patterns in different aquifer systems over the long-term, contributing to more effective, forward-looking and resilient groundwater management strategies. This supports livelihoods resilience as individuals can better manage their water resources and prepare for dry spells.
References and further information
- Liza et al Changes in global groundwater organic carbon driven by climate change and urbanization. Nature Comms
- Cuthbert et al. (2019) Observed controls on resilience of groundwater to climate variability in sub-Saharan Africa Nature
- Dunning et al, (2018): Later Wet Seasons with More Intense Rainfall over Africa under Future Climate Change. J. Climate,
- Walker et al (2018), Insights From a Multi‐Method Recharge Estimation Comparison Study. Groundwater.
- Kotchoni et al. (2018) Relationships between rainfall and groundwater recharge in seasonally humid Benin: a comparative analysis of long-term hydrographs in sedimentary and crystalline aquifers Hydrogeology Journal
- Damkjaer, et al (2017) The measurement of water scarcity: Defining a meaningful indicator, Ambio
- Jasechko, et al (2015) ‘Intensive rainfall recharges tropical groundwaters’ Env. Res. Letters
- Tarnavsky et al (2014): Extension of the TAMSAT Satellite-Based Rainfall Monitoring over Africa and from 1983 to Present. J. Appl. Meteor. Climatol.,
- Garcia-Landarte Puertas et al (2014) “Roads for water: the unused potential”, Waterlines
- Steenbergen,et al (2014) “How to Make Water Wise Roads” IFAD,
- Ascott et al. (2020) In Situ Observations and Lumped Parameter Model Reconstructions Reveal Intra‐Annual to Multidecadal Variability in Groundwater Levels in Sub‐Saharan Africa, Water Resources Research, Volume 56, Issue 12 December 2020
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UPGro - African Groundwater 2020 