Rainwater Harvesting: What is it?

Rainwater Harvesting (RWH) is a realistic option for many across Africa. Like other solutions, it is not a fix for all (and especially not as a lone solution) however, I do think it is suitable especially in conjunction with other measures such as the use of groundwater.

RWH as defined by Liniger et al (2006) is the use of technology and instruments, to collect the water for agricultural and domestic use. It is considered the single most important means to increase agricultural productivity (Getaneh andTsigae 2013). There are two types of RWH. Ex Situ RWH which is where the water is stored in natural or artificial reservoirs such as wells or pond. In Situ on the other hand, enhances infiltration and water holding capacity, aiming to maximise the benefits of rainfall where it falls (Vohland and Barry 2009). Figure 1 shows a breakdown of the different types of Rainwater Harvesting management systems as classified by Ngigi (2003).

Figure 1- Classification of Rainwater Harvesting systems (Ngigi 2003)

Agriculture is the main economic activity in SSA and supports about 67% of the population, 60% of which depend on rain- fed agriculture (Yosef andAsmamaw 2015), generating about 30-40% of each country’s GDP (Rockstrom 2002). Therefore, climate change is set to affect these 60% dramatically, not only socially (their lifestyles) but economically too (in reducing their income and making it more temperamental).

One of the main reasons for low crop production in semi-arid areas is due to high losses of surface run off during high intensity rains and high evaporation losses (Yosefand Asmamaw 2015).

Rainfall intensity in SSA can often be greater than the infiltration rate and so triggers excess runoff exacerbating the problem.

RWH looks like a promising solution. Over the course of the blog I will be focusing on the strengths, weaknesses, and implementations of these techniques across Africa and what this means for agriculture as a whole.