Groundwater : The Future May be Bright

Welcome to my first back to back post regarding the future - groundwater !

Having previously briefly eluded to the potential of groundwater for water security in Africa, I would like to define ‘groundwater’ for those readers who are not sure what it’s all about. Groundwater is “the water found underground in the cracks and spaces in soil, sand and rock. It is stored in and moves slowly through geologic formations of soil, sand and rocks called aquifers” (Groundwater.org, 2015). In terms of its dependence, groundwater is a source of recharge for lakes, rivers, and wetlands and I am now going to explore whether it has the potential to assist Africa’s agricultural yields as surface water supplies dwindle in the face of climate change.

“Groundwater is the only reliable source of freshwater in many semi-arid and arid regions where surface waters are seasonally or perennially absent” (Taylor et al., 2012). This paper explores the relationship between rainfall and recharge rates on groundwater resources in Makutupora, Tanzania. Groundwater recharge is a hydrological process where water seeps downwards from the surface (surface water) to underground (ground water). Taylor’s research found a non-liner relationship between precipitation and recharge rates as recharge largely occurs during heavy rainfall. The existence of a recharge threshold means that evapotranspiration plays a crucial role in hydrological dynamics across Africa. I.e. if evapotranspiration is high this means that more water is lost from the surface and so will require more water before recharge occurs.

Although this sounds like a negative, if we put this process into the context of climate change (whereby heavy rainfall events are becoming less frequent yet more intense), all other things being equal we will expect to see an increase in the number of major recharge events – increasing groundwater volumes.

As countries globally tackle the combination of increased demand and dwindling supplies for water, this theory of increased groundwater arising from more extreme weather events is very intriguing. From Taylor’s research in Makutupora it is clear that extraction rates (from groundwater sources) have already increased from around 0.1 million metres cubed in the mid-20th century to 0.9 million metres cubed by 1990. This phenomenon could result in one of few blessings arising from climate change and has the potential to maintain sustainable groundwater levels. In this regard I suggest that groundwater recharge could play a huge role in helping Africa achieve food security, alleviate poverty and increase agricultural productivity as the climate becomes more unpredictable (Villoth, 2013).

Nevertheless it is important to bear in mind that accessing groundwater is not always possible as the relevant technologies and wealth required evade many rural communities. In coming posts I will be looking at large scale irrigation projects and the implementation of new technologies to help Africa access more water and achieve greater crop yields in the current climate.