Solutions: Rainwater Harvesting

I have already explored some solutions (drip irrigation, mulches, contour hedgerows etc.) surrounding inefficient water use. I am now looking at a solution not just for inefficient water use in agriculture but for lack of water.
Rainwater harvesting is the collection of rainwater for reuse in the domestic, agricultural or industrial sectors rather than letting it runoff and be wasted.

Rainwater harvesting has been around since the third century BC where it was used for irrigation in Tamil Nadu (India) but it has great potential within the African continent.

Rainwater harvesting in Africa (Source)

In a continent of highly variable rainfall and frequent droughts leading low productivity and food insecurity rainwater harvesting is a way of storing water during times of rainfall that can then be used when there is none. It is particularly useful for rainfed systems which are dependent on the natural variability of rainfall (Karpouzoglu and Barron 2014). Having this water available is a solution to food security and makes water use and crop production more productive and efficient (Dile et al 2013; Mwenge and Taigbenu 2011; Karpouzoglu and Barron 2014). Furthermore, rainfall patterns are the main factor effecting crop production in Africa (Muller et al. 2011) and with climate change creating extreme droughts and shorter wet seasons rainwater harvesting is seen as a major form of adaptation against climate change (Lebel et al. 2015).

However, as Getnet and Macalister (2012) note (as does Mwenge and Taigbenu 2011)the research and focus of rainwater harvesting has mainly been on domestic use such as Ward et al's (2012) study into rainwater harvesting in an office block. Rainwater harvesting may be low cost and simple technology but it requires high labour input to set up (Van Heerden et al. 2005). In poor rural communities they must rely on local (hopefully free) labour otherwise this low cost endeavour would be undermined if labour costs exceeded the cost of buying it.

Rainwater harvesting, like drip irrigation, is incredibly useful in the African continent - especially within agriculture because it is low cost but unlike drip irrigation it is easy to maintain and useful for all portions of society (as it can be used domestically as well). Used in conjunction with drip irrigation it could boost crop productivity in Africa.

Identifying the Problem - Inefficient Water Use

This blog post acts as a strand to draw upon a few previous blog posts that have touched upon the issue of inefficient water use within agriculture. It is an argument throughout that water use within agriculture in Africa is inefficient but how is it inefficient?

The Environmental

• Water is lost through runoff or evapotranspiration. 
• Wallace (2000) suggested that the relief and gradient of the land determines efficiency of water use in both irrigated and non-irrigated land. Where gradients are steep then runoff is increased and infiltration is reduced. 
• Water supply effects the productivity of field crops more than any other environmental factor (Patterson 1984). This means a shift from increasing area of crop production to increasing efficiency is required. 
• Variability in rainfed yields is large (Kijne 2001). Therefore consistency can increase yields as can irrigation. 

The research into the inefficient use of water resources within the agricultural sector has mainly focused on the environmental characteristics and has demonstrated a need for change in the form of (technological) innovation. 

The Human
It is important to note that inefficient water use cannot be solely blamed on environmental factors with the Millennium Ecosystem Assessment, in 2005), estimating that between 15-35%  of irrigation withdrawals being unsustainable because farmers took more water than was needed. The FAO built on this and suggested that 60% of water diverted for irrigation is wasted (however, this wastage could be down to either human or environmental factors or both). Its suggested that losses are due to improper system design such as inadequate lining of water channels (Dawn) and poor maintenance.

An interesting concept that has not been touched upon in any of the research or articles that I have read is that if food is wasted than surely the water used to grow it is wasted too and therefore that makes it inefficient. It is a curious link which has seen no discussion but I feel its an important point. If we waste less food then we improve efficiency.

The Political
I'm bringing this one in because the discussion of government accountability and preparedness still rages on in the media - BBC News, The Globe and Mail, and the Poultry Site. as South Africa's drought persists. It was originally covered in a previous blog post that essentially drew the conclusion that the responsibility to improve efficiency of water in agriculture is as much the farmer's responsibility (argued by Wallace) as it is the government. It is the government who can store and manage water (along with private companies) which would mean water is available during periods of water stress.

Inefficiencies in water use within agriculture are more complex than environmental characteristics of human wastage and its a complex interaction of these with the political that means waster use within Africa is very inefficient. As Kijne (2001) and Howell (2000) note that efficiency within agriculture has to increase to meet food security needs as the population continues to explode - something which has  been discussed already on this blog.

The Water Apocalypse - Population, Climate Change and Agriculture

It has taken nearly 7 weeks to get to this point but in this blog post I aim to outline the problem of the problem -solution to water use within agriculture. It is a U-turn in the trajectory of this blog but I think it's an issue that has only been touched upon a little with past blog blogs.

There is a clear link between water and food, both are essential for human survival and food cannot be grown without water. So what is the problem?

• Population projections are as much as 9 billion by 2040 and 11 billion by 2050 (International Data Base).
• As countries such as China, India, Brazil, Indonesia etc. develop an increased quality of life increases the demand for higher quality food - mainly meat sources. This requires more water, more space and more energy compared to plant sources. 
• The impact of climate change on plant growth and water resources is uncertain, unpredictable and potentially unsolvable. 

UN Estimations for Future Population Projections (UN)

The Population Problem

The population crisis that this world faces is more than a numerical one, with more people the quality of life we enjoy is threatened as populations grow at a faster rate than food production meaning there is less food to go around - people go hungry today so the number of people going hungry will only increase as food prices increase due to higher demand or lower supply. Ararso et al. (2005) and Pfister et al. (2011) are both in agreement that the stress on water and hence food is a result of population growth and higher caloric food demands. Both the focus of their work is in sub-Saharan Africa which presents the same problem but in a different setting. 

Sub-Saharan Africa, and Africa more generally, struggles to cope with the population boom it is experiencing. Water systems have limited extent or function significantly below their potential meaning that only 16.8% of the potentially irrigable land has been developed for irrigated agriculture (Ararso et al. 2009). In otherwords, food production can be higher in Africa but the main limitation is the financial capacity to invest in water resources. 

There is a lot to consider here in just a simple blog post, the intricate web of problems that spread out across Africa is hard to decipher and it mostly comes back to finances. Often, as Pfister et al. (2011) notes intensified agriculture is not viable in many locations because ti puts a strain on the water resources. 

Can Africa Cope? (EasterBrook)

Climate Change
I won't dwell upon this too much because the content of which could create an entirely new blog post (or indeed blog). To summarise, the effect of global warming and climate change on Africa's water resources is incredibly uncertain and thus it is important to prepare for a worst case scenario.

Summary of the Effects of Climate Change in Africa (Source)

More Problems?
For Wyman (2013) the problem is not just population and climate but also the way water in Africa is used incredibly inefficiently. There is high wastage and irrigation depletes groundwater so that it is not sustainable. For Wyman, the water crisis is the most immediate environmental problem because water is vital for a good quality of life (and a basic quality of life).

Whilstshore et al's (2013) work modeled the effects of climate change and population on water and food resources. The focus was globally rather than Africa but suggested that there would be a reduction in crop yields by 2050 due to climate change and population (clearly there is link between population, climate change and environmental degradation that can't be explained here). Their conclusions were that the effects of climate change on water is uncertain and that the effects of CO2 on plant physiology is  major driver in changes in crop productivity. However, they themselves admit that their study is constrained by observations and highly uncertain. The assumptions they make are broad, vague and not specific to locations or time periods but are still incredibly useful in hypothesizing future changes.


In this blog post I have barely scratched the surface of these interlinked problems - some of which can be explored in more detail on other blogs - but show a general trend in that there will be a water shortage and a reduction in crop productivity countered by an increased demand for food and space. It is important to note that some of the issues can be solved - such as the inefficiency in water usage (some solutions have been offered in a previous post). My next blog post will look at more potential solutions to increasing/maintaining crop productivity in Africa for future populations.