Water, Climate Change and Africa

I was drawn to writing a post on the link between water, climate change and Africa by an article discussing international agreements regarding climate change such as this year’s COP (Conference of the Parties) climate summit. African countries will see some of the most severe climate changes in the future with six of the ten countries most affected by greenhouse gases being located in Africa. This is all despite the fact that the continent receives just 5% of global climate funding. On a more positive note, ‘every single African country has included adapting agriculture as part of their climate change strategies submitted to the United Nations Framework Convention on Climate Change (UNFCCC).’ Therefore this is not a question of willingness but rather one of finance. To investigate this further I wish to look into the funding behind agriculture in Africa to understand how it here can adapted to changes in rainfall patterns, droughts, etc.

The news article highlights three main areas to target investment to ensure the future of African agriculture. These are: better soil management, water control and climate-risk management. The first of these is very important for maintaining high crop yields. Research has found that soil nutrient levels decrease with distance from water points. The areas close to water points also had a lower soil salinity level. Salinity is a key cause of land degradation; overly saline soil is unsuitable for growing the majority of crops. This is another reason why droughts are especially damaging for agricultural business as in addition to killing off crops, it can also leave land unsuitable in the long term. A concerning statistic is that 65% of soils in Africa are likely to be degraded. This statistic combined with the fact that climate change will likely cause further degradation suggests a concerning future for all of Africa, especially those involved in the agriculture sector. One idea is to plant crops that are natural fertilisers of the soil such as chickpeas and lentils that add nitrogen. This simultaneously combats the issue of degraded soils and sustains an income for farmers in the short term. It is therefore an alternative to growing existing crops.

The second of these target areas for investment is water management. Currently there is a lack of knowledge on irrigation water values in small-scale farming schemes. In the future, farmers will have to pay for the water they use and therefore the issue of water management is of economic and environmental importance. It is extremely complicated to assess the consumption of water for irrigation because there is a great variability between irrigation schemes and the type of crop grown. This makes it difficult to estimate the overall dependence on water systems and therefore how to control water resources. As well as improving the knowledge of irrigation water demand, there are a number of techniques, such as drip fed irrigation, which can be applied to reduce water consumption universally. Drip fed irrigation reduces water usage as the water is applied directly to the root of the crop through a distribution system of pipes, meaning less water is lost through evaporation and the minimum amount of water required can be added as water flow can be controlled. This research and equipment however requires funding and it reflects back on the key issue for African countries – funding.

Figure 1: Drip fed irrigation in Kenya

Climate-risk management is the final area that requires investment. This can involve the development of new crops such as climate-tolerant and disease-resilient varieties. In sub-Saharan Africa, there will be a shortage of cereals in the near future if the status quo is maintained. Insect resistant varieties of maize and cotton suitable for this area of Africa have increased crop yields. The use of genetically-modified crops, especially drought-resistant varieties, could reduce water consumption for irrigation as well as increasing the chance of survival during periods of very low rainfall. Climate-risk management is the least suitable of the three methods to implement across Africa because it would take longer to implement than the other two methods mentioned earlier.

Overall, as a continent, Africa is fully committed to mitigating the effects of climate change on the agriculture sector and have the techniques available to achieve this that are suitable for this part of the world. What they do lack however is the financial backing to implement such projects and this is where the international community should be open to helping African countries. Without financial support the future of agricultural sectors across Africa is concerning, risking crop deaths and heavily degraded land that is unusable for crops. It would leave people across Africa in an extremely difficult situation.

North Africa's problem with water

Northern Africa is one of the hottest and driest places on the planet with very low rainfall levels. The Middle East and North Africa Region (MENA) is the most water scarce area worldwide. This brings great problems in terms of water shortages for both domestic use and farming uses. In West Africa and North Africa (WANA), 75% of water consumption is for agricultural uses. This means that the agricultural sector is more greatly affected with fluctuations in water resources and therefore requires better water management than other regions of Africa. By looking into the different factors affecting North Africa, it will be possible to better understand the water difficulties facing this region and see what farmers are doing to combat these effects. This may be particularly important for other areas that are not currently water scarce but will become so in the future due to climate change.

First, we begin with one of the key issues surrounding water facing North Africa – climate. North Africa is a naturally hot and dry region that is prone to droughts. Around 85% of MENA is desert and climate change is having a profound effect on this region. Much of the rainfall in North Africa therefore occurs in the winter season and it is dry during the summer season. As can be seen by the map below (Figure 1), the dry season is very long lasting in Northern Africa, lasting at least 7 months in most areas and in some places the full year. This means that the growing season in these areas is very short without irrigation techniques. Water resources are extremely scarce in this region presently and climate change is only going to exacerbate this. A paper by Droogers et al. (2012) on how water resources in North Africa will change towards 2050 found that demand for water will increase in the MENA area under all climate scenarios as a result of population growth. This, combined with the fact that climate change will lead to more sporadic and intense rainfall, suggests that the future for North Africa and water resources is extremely problematic.

Figure 1: Months with less than 25mm rainfall in Africa

One of the fall back options for areas under drought conditions is the availability of groundwater which has built up over centuries and recharges gradually. Under North Africa there are large stores of groundwater but there is a complication with these reserves. Figure 2 shows the depth to the groundwater stores across Africa. As can be seen, much of the groundwater stored under North Africa is located deep underground with much being more than 100 metres below ground level (mbgl). This is significant because water stored deep underground is more difficult and more costly to extract and many poor farmers would not have access to the more sophisticated technology required to extract this deep groundwater. This exacerbates the problems cause by droughts as farmers cannot access the stores of water under their feet that could allow them to sustain crops longer into the dry season. As it is clear to see, North Africa has a much more severe problem with water shortages than any other area in Africa because of the climatic conditions and the unavailable groundwater resources.

Figure 2: Depth to groundwater (metres below ground level)

So what do farmers in North Africa do to counteract these problems? Two methods of improving productivity are supplement irrigation and water harvesting. Supplemental irrigation involves the adding of small amounts of water to crops during critical growth phases in order to boost the overall yield. This can substantially increase the crop growth and only requires water collection and storage during peak rainfall periods. However, farmers need the knowledge of these critical growth phases to know when irrigate their crops. The other method mentioned, water harvesting, is defined as “the process of concentrating precipitation through runoff and storing it for beneficial use”. This can be crucial for generating enough water to irrigate crops to the required level. In addition, farmers in Morocco are involved in projects that introduce drought resistant crops. These crops require less water but produce the same grain yield meaning that farmers are less vulnerable to long droughts and serious water shortages.

North Africa suffers greatly from water shortages in a variety of ways but have developed techniques to adapt. North Africa is an excellent example for areas that will experience longer droughts and less rainfall in the future as a result of climate change. The approaches to water scarcity in North Africa are relatively easy to apply to other areas of Africa and the world and emphasise people’s ability to adapt to adversity. These systems suggest a hopeful future for areas at risk of water scarcity in the future.

Solar powered irrigation

Figure 1: SunCulture solar irrigation

Today I read a thought-provoking article on the development of new technology for use in East Africa that combines the use of solar energy with the application of irrigation to cropland. This is quite different to some of the irrigation techniques I have mentioned before such as motorised pumps which do not have this eco-friendly focus. The concept of solar power irrigation is interesting as, for it to be considered useful, it needs to be both technically and economically feasible and this is much harder to achieve in certain areas of Africa due to lack of finance. One of the key ways, solar energy generated from cells would be used to provide irrigation is through the pumping of water from underground stores and then pumping the water onto the crop land.

The American company mentioned in the article – SunCulture – is a company already selling this technology in Kenya for up to $2,400 and they have plans to expand into other countries in Eastern Africa. Importantly, just 4% of Kenya’s arable land is currently irrigated meaning that food production is far below maximum capacity. In previous posts, I have mentioned the costs of irrigation methods such as treadle pumps ($20 - $100) and many of these methods are unaffordable for small scale farmers so $2,400 solar power irrigation is a far out of reach for the majority of farmers across Africa. SunCulture have worked around this through a gradual repayment scheme where farmers pay in installments throughout the year and more is paid when they have the money to pay around harvest time. In addition to the solar irrigation technology, farmers are also given access to expertise from different suppliers which can help to boost yields up to four times.

This all sounds very promising but are solar energy irrigation techniques feasible on a larger scale for most farmers? With farmers in sub-Saharan Africa being located at low latitudes, the output from solar cells is likely to be much higher than other areas as solar radiation is more concentrated around the equator. Further to this, crops are typically planted in the spring and summer and this period coincides with increases in solar radiation. The depth of the well that water needs to be drawn from is important. A greater solar panel area is required to pump water from greater depths and the area also depends on the amount of water the crop being irrigated requires.

In my opinion, this method is very feasible both technically and economically. In Africa, there is sufficient solar radiation at the correct times of the year to provide enough solar power to pump water, much of the underground water stores are at relatively shallow depth and the financial barriers are overcome by companies willing to extend time to farmers to pay them back. This is all important as well as the fact that fuel to power motorised pumps is likely to increase in price in the future. Personally, I feel that this method of irrigation has a very important role to play in the future of farming in Africa.

Paper Review: Rainfall and Water Resources Variability in Sub-Saharan Africa during the Twentieth Century

As I have pointed out in previous posts, rainfall and water resources have a key impact on the ability of farmers in Africa to irrigate their crops. This is where I felt it would be interesting to review a paper focusing on this issue and how the access to water has high variability. The paper, written by D. Conway, A. Persechino, S. Ardoin-Bardin, H. Hamandawana, C. Dieulin and G. Mahé, is titled ‘Rainfall and Water Resources Variability in Sub-Saharan Africa during the Twentieth Century'. It will be interesting to look into one area where there is much variability, sub-Saharan Africa that has a serious problem with water shortages. In this post I will study this paper in detail, attempt to draw some conclusions from it and find places where the research may be lacking or need extending.

The aim of this paper from the Journal of Hydrometeorology is to study the spatial and temporal covariability of rainfall and river flows in the sub-Saharan region of Africa. The research is categorised into four key regions, central, south, east and west. The data used in this research come from a variety of sources, mainly the Institute de Recherche pour le Développement (IRD) and other national and international sources. The focus of the paper is on the changing rainfall and river flow levels on a temporal scale from 1901 – 2002, the entire 20^th century, to see if the levels were variable throughout this century. The research studies these trends at a basin scale rather than a nation state level as this highlights that the focus is on the hydrological issues as hand rather than the political issues. Data on rainfall and river flows in sub-Saharan Africa is not perfect, there is often a lack of data for certain regions and the chronology may be incomplete or lack temporal resolution (not be recorded frequently enough). In my opinion, this paper is attempting to come to some more general conclusions at a regional level for rainfall and river flow rather than focusing on a single river basin to carry out this research. Although this provides more conclusions, it can lack detail and miss certain local differences that may also have an influence in rainfall and river variability such as water that is diverted for irrigation at a smaller-scale. There is also a concern with some of the records dating back to the early 20^th century. The data collection techniques from this time are likely to be far less sophisticated and this means that some of the conclusions may be lacking in certainty.

So what did this research actually find? One of the most interesting points that I picked up from reading this paper was that through time there has actually been a shift rather than a trend in the West African rivers. This shift occurs between the two time periods mentioned, 1931-1960 and 1961-1990. The authors go on to state that, ‘Proportionally, the shift is much greater in river flows (from -13% to -51%) than rainfall (from -7% to -14%).’ This means that river flows during the second period are a step below those in the early 20^th century. This is even more interesting when we know that the three other regions in this research do not show much variation between these two time periods, therefore West Africa is far more hydrologically unstable (see graphs in Figure 1). Something occurred during the 20^th century in West Africa that has not in the other regions. The big shift in river flows but not rainfall suggests that something or someone is altering the basin environment and changing how the river flows. Although nothing is mentioned in the article as to what has caused this, I personally feel this may have something to do with large scale dam and irrigation projects that are used in West Africa in many basins to boost food production through irrigation. This would account for the large variation in river flows but less variation in rainfall. 

Figure 1: Annual rainfall (black line) and river flow (gray line) for rivers in West Africa

Another of the figures in the paper (Figure 2) shows the strength of the relation between rainfall and runoff for different rivers studied. Many of the rivers show very strong relationships between rainfall and runoff over the thirty year periods. It is then intriguing to look at which regions have strong and weak relationships and question why this is the case. The overall relationships suggest that variations in rainfall account for the majority of runoff variation. In the instance of East Africa, the geology and unique Rift Valley system accounts for the unusual patterns observed there. Lake Victoria outflows show a very weak relationship to basin rainfall.

Figure 2: Strength of regression between rainfall and runoff for the 30 year periods

To conclude, this paper gives a very clear overview of rainfall and runoff trends through the 20^th century. It is important to remain critical of data in all instances. Data in this research is from a variety of sources that may be inaccurate or incomplete which can leave us drawing conclusions where there are none. I feel that this paper has achieved the aim of looking at these two hydrological characteristics both spatially and temporally and put forward some interesting data and conclusions to better understand the background to water resources in the sub-Saharan Africa region. Personally, I find it very interesting to look at some of the reasons behind the results that this piece of research has put forward despite the possible uncertainty with the results.