Farmers reach for groundwater: a possible solution?

We know from the last blog post that water resources in Africa are highly variable and unreliable. With a growing population, reducing the amount of agricultural produce in Africa would certainly not be a viable solution to these issues. This continent needs to up keep levels of food production (if not increase them!) but how is this possible with such inconsistent water supplies?

Groundwater. The groundwater stores in Africa, in my opinion, could be the future for increasing agricultural output and allowing Africa to not only meet national food demands but increase exports too. Africa rests on extensive stores of untouched water supplies which could potentially, if utilised in the right way, alleviate their water scarcity. But what way is the right way?

MacDonald et al (2012) estimated Africa to have around 0.66 million Km³ of groundwater storage. Figure 1 shows many areas to have substantial stores, the most significant being the large sedimentary aquifers in North Africa. This water may not be evenly distributed, however there are significant stores all across Africa- it is the most widely distributed store of freshwater in Africa. So why aren’t these areas using these stores?

Figure 1- Groundwater stores across Africa (MacDonald et al 2012)

The type of aquifer makes it unavailable for abstraction. The hardrock systems are low yielding (MacDonald et al 2012). However, despite this, even these are significant because they are considerably more than the volume abstracted manually using hand pumps by the widely distributed small hold farmers across Africa. They also act as a buffer against the variations of water supply because the groundwater is stored for hundreds of years and can be abstracted for use during drier periods (MacDonald et al 2009). 

Africa is characterised by many small scale farmers sparsely distributed all across the continent. In a similar way groundwater is distributed all cross the continent as shown in figure 1. Unlike large rivers this means that farmers remote from the river or lake can still have access to the water.  Furthermore, they do not pump water as intensely as the large irrigations schemes and so groundwater stores, which may be small in volume, will be sufficient for unintensive use by the small hold farmers. Groundwater also reduces political tensions amongst users. This is because if the ground water is to be intensively pumped the rule of the ‘cone of depression’ means that only water stores from immediate and similar geology will be used and so distant farmers will not be affected. This reduces the potential for conflict arising with larger rivers such as the Nile where countries go to war over water rights and access to the source/ river. Therefore, the over abstraction by one farmer would only be detrimental to themselves and this solution erases issues of transporting water over long distances and the conflicts that come with sharing one large source over many national boundaries.

Furthermore, as explained in the previous blog post, climate change is likely to cause less frequent but more extreme rainfall events. This is favourable for the replenishment of groundwater sources. Taylor et al (2013) conducted research on groundwater resources in Makutupora, Tanxania and showed that recharge occurs during heavy rainfall events. This is to do with higher evapotranspiration rates resulting from warmer temperatures which means a larger volume of rainfall is needed to induce recharge.

So groundwater seems like a viable option. It is accessible all across Africa, it works with the projected changes in precipitation, and reduces potential for conflict. But although I think it is the most suited solution for now, there are still questions that remain. Can local farmers afford the hand pumps and the maintenance? What is the quality of water like? There is still a lack of detailed knowledge and understanding about groundwater as a solution.