Water - Here and Gone Again

Water and Africa have a very tricky relationship. Often, where water is needed most, it can’t be found - in other cases, some areas have more water than they could possibly need. The balance between supply and demand is barely ever struck, and when it is, it’s often temporary.

You see, water supply across Africa has an infamous habit of being extremely variable. As Taylor (2004) explores, this is a result of many factors, all with their own part to play. One of the most obvious is topography. This affects mostly what is known as “High Africa” (or the East African Rift System), which is made up of the South and East of the continent, where average elevations are above 1000masl. This is shown on the map below (although the odd choice of colours does it few favours).

                                Topography Map of Africa - Source: http://maps.unomaha.edu/peterson/funda/MapLinks/Africa-2/Africa2.htm

Many effects of this elevation are old friends of geographers; you have orographic rainfall, and of course its partner in crime rain shadows. Surface flows are also directed down valleys and through rifts, and often these can become trapped and form lakes.

There is, however, a somewhat more elusive effect of topography in Africa. Spared, by its equatorial climate, from glaciation over the past few million years, the crystalline rocks (such as granite and gneiss) that make up the majority of Africa’s surface have undergone long-term biochemical weathering, creating the red earth that is so famous today. The reduction in mass that resulted from the creation of this reddish regolith in many areas has caused uplift of the bedrock, which in its own turn has caused it to split, creating deep fissures.

In areas of high rainfall, sediment is often washed into these fissures, stripping the bedrock clean. This has dramatic effects on water availability; overland flow becomes dominant on the largely impermeable bedrock, meaning the majority of water available can be found in river discharge or stored in lakes. On the other hand, areas that retrain their regolith are great at storing groundwater, and water can be found almost year round.

Climate is also another deviant in causing the variability of water supply in Africa, with its most famous menace being the Inter Tropical Convergence Zone (or ITCZ). Caused by pressure gradients created by unequal heating of the Earth, this big band of rainfall is never in the same place for long. It migrates up to the Tropic of Cancer in our summer, before travelling down to the Tropic of Capricorn for Christmas. This is great for the countries that lie in-between, but if you’re a country like Nigeria which is only visited once a year, you can find yourself left out in the cold (or should I say dry?).

Understandably this duo-variability makes successful agriculture an incredibly complicated process. Africa often has difficulties with food security caused by droughts, floods, or anything in-between.

Water variability is not something unmanageable though. In fact, as Swaminathan (1992) preaches, with detailed understanding of resources and the right management techniques, issues of water scarcity can often be circumvented. Swaminathan divides Africa into several (if basic) agricultural types such as Arid Ecosystems, Wetlands and Coastal Areas, and highlights key strategies that he believes will lead to greater agricultural success in these areas. Although the list is far from exhaustive, it is a start, and goes to show how understanding of an area can lead to it being harnessed to its full potential.

This is also the case in Swaminathan’s analysis of water management techniques. He discusses several, such as aquifer and farming-system-specific management (although with brevity) and discusses the advantages that they can bring to water supplies across the continent.

Swaminathan, in my opinion, highlights a very important point. While water variability does create huge barriers to successful agriculture, these are barriers that can be subverted. Through the understanding of both the environment in which you are living and the water management techniques at your disposal, it is possible to adapt agriculture in such a way that it can thrive. Over the next few months, I will explore just how this is done across Africa, from the macro to the micro, private to public, high Africa to low, and hopefully, I’ll be able to show you that African agriculture is fighting back. 

 Swaminathan, M.S. (1992) 'Agricultural Production in Africa', in Obasanjo, O. and d'Orville, H. (eds) The Challenges of Agricultural Production and Food Security in Africa, New York: Taylor & Francis.

Taylor, R.G. (2004) 'Water Resources and development challenges in eastern and southern Africa', in Bowyer-Bower, T. and Potts, D. (eds.) East and Southern Africa. Regional Development Text, RGS-IBG Developing Areas Research Group, London: Addison Wesley Longman, 198-228.