Good local hydrogeological understanding and monitoring over time is required to define the sustainable yield of wells and boreholes, particularly in weathered basement aquifers, and from this assess opportunities for domestic, agricultural, commercial and industrial activities, and the associated risks.
Many low-productivity fractured aquifers are capable of supporting handpump boreholes, with no evidence of climate change significantly reducing the sustainability of domestic rural water supply. However, studies indicate that these highly localised aquifers would not be capable of supporting the potentially higher abstraction rates of motorised pumps, which is an important consideration if pumps are to be upgraded to support increased domestic use or irrigation, as is the case with the move towards solar pumps.
In Kenya, geophysical analysis of a larger aquifer system, rather than individual water points, revealed two major groundwater resources in ancient, buried riverbeds (palaeo-channels). Despite major commercial water users drilling productive boreholes for several decades these major water resources were missed, but now figure in long-term planning for water resource management for all users. Aquifer modelling has also indicated that abstraction licences from the deep aquifer for mining and irrigated agriculture are sustainable, though this was not known previously.
Whilst this finding is far from novel, UPGro evidence reinforces the point that there is no substitute for doing the basics professionally and having competent national institutions with the mandate and resources to maintain and make accessible national geological and hydrogeological databases and maps.
A barrier to investment in targeted investigation and monitoring is the large geographical areas of many Sub-Saharan countries in relation to their population distribution. Two tools developed through UPGro can help address this. The first is a method of classifying zones for manual drilling based on remote sensing data, which was tested in northwestern Senegal ; the second is the Africa Groundwater Atlas,which provides a starting point of baseline information on which more details studies can build upon.
References and further information
- MacDonald A., et al (2019) Groundwater and resilience to drought in the Ethiopian Highlands, Env Res Letters
- Maurice, , et al. (2018) Characteristics of high-intensity groundwater abstractions from weathered crystalline bedrock aquifers in East Africa Hydrogeol J
- Fussi, et al (2017) Classifying zones of suitability for manual drilling using textural and hydraulic parameters of shallow aquifers: a case study in northwestern Senegal, Hydrogeol J
- Manandhara et al (2020) Shallow aquifer monitoring using handpump vibration data, Journal of Hydrology
- Africa Groundwater Atlas