The Potential of Groundwater

The volume of groundwater in Africa is estimated to be 600,000 km³ but it doesn’t get the attention it deserves (Macdonald,2012). To put this in perspective, that is 100 times more than the ‘renewable freshwater resources' and 20 times more than the  freshwater  in African lakes. Furthermore, Falkenmark’s Water Stress Index, once seen as a definitive measure of water scarcity in Africa, only measures water scarcity through river discharge, completely ignoring groundwater!   Today I will discuss the potential of groundwater irrigation, particularly focusing on the Sub-Saharan region of Africa. 

Groundwater Distribution 

 

There are many different  groundwater irrigation schemes in Africa through privately as well as publicly funded projects. Specifically, Sub-Saharan Africa has huge potential for increased agricultural production as only 3.3% of arable land is irrigated, compared to 37% of arable land in Asia(Vilhoth,2013). 

Picture 1 (Macdonald,2012,5)

This shows that the greatest volumes of ground water are in Northern Africa, with Sub-Saharan and Southern Africa seeing much lower volumes. 

Potential of Groundwater?

One potential positive impact is the economic advantages of groundwater extraction. You et al in (2010) found small-scale irrigation projects return a significantly higher proportion of capital investment than large-scale irrigation projects such as dams. Specific case studies in Ghana and Malawi by Dittoh and Kamwamba (2013) respectively found that the ‘value added per area’ in groundwater irrigation zones was more than twice that of zones served by other irrigation systems.

Groundwater irrigation usually focuses on ‘cash crops’ which yield ‘higher and more stable output, higher productivity and net incomes compared to rained irrigation' (Vilhoth, 2013, 380). Further, groundwater irrigation is often used in addition to rain-fed agriculture, allowing farmers to produce a more diverse range of products. Farmers often prefer groundwater, as it allows a greater level of control, than rain-fed irrigation which is dependent on seasonality. Studies have found that it tends to be wealthier farmers who are able to invest in  groundwater irrigation, partly due to the expense of procuring the necessary equipment. Prices for manual pumps range from US$ 60-US$ 360 and motorised pumps can cost up to US$2000 (Vilhoth, 2013,320). Considering that the GDP per capita of Sub-Saharan Africa is US $1,591, a motorised pump is often an option only for the most economically privileged(World Bank,2020).  It should be noted  that schemes which use piped water have been costed at 50% less (Hope,2020). However, the supply chain of pumps in Sub-Saharan Africa is currently inadequate. Pumps are often available only in urban areas and there can be a lack of infrastructure to deal with maintenance. Subsidies have been proposed to solve this, but this can in turn lead to over-reliance on government resources and a resulting  lack of investment of personal capital into farms, disincentivising production.  

 

Another cost barrier derives from the cost of land tenure in which to carry out groundwater extraction and here richer farmers benefit again. Further, the inability for smallholder farms to access a larger market for their produce due to their remote location, often makes groundwater extraction unsustainable due to its cost. Also, many smallholder groundwater irrigation projects in Africa are unregulated and implemented with little knowledge or care for the environment. The NWMP in Kenya states that for sustainable use of groundwater, less than 10% of its recharge value should be used (Olago,2018).But it is feared that unregulated use of groundwater could lead to depletion of this resource. Groundwater benefits from being located away from urban and industrial environments, meaning it is often cleaner than surface water. However, in arid and semi-arid environments, it is possible that evapotranspiration in areas of ‘previously uncultivated land may generate transitory salt leaching and soil and groundwater contamination upon clearing and irrigation’, leaving an accumulation of salt on the surface soils (Vilhoth,2013,385).  

 

Looking Forward

There is obvious potential for small holder farmers to exploit groundwater in Sub-Saharan Africa, to develop and increase their crop yield. I end with Gaye’s (2018,119) paper, which calls for  sustainable management of groundwater resources in Africa through implementing ‘institutional coordination and stakeholder participation frameworks, information management programs and capacity building programs' and evaluation of risks and strategies when groundwater irrigation is used. Gaye emphasises the need to help poorer communities, who face the biggest challenge in accessing this valuable resource.