Improving Food Security In Africa Through Water Harvesting Technologies
Agriculture remains a critical sector in Africa's socio-economic development and growth. This is because smallholder farming in Africa accounts for more than 60% of Africa's population and approximately 23% of Africa's gross domestic product (GDP). Water availability and access are vital inputs for agricultural production and food security. As such, crops, vegetables, and animal rearing require water to enhance essential food production. However, in many parts of the African continent, there is persistent limited access to quality water. Furthermore, the quantity of clean water remains limited due to management and treatment incapacities becoming a fundamental impediment to farmers' development.
Water impacts every element of human life, including health, agricultural production, food security, technological advancement, and state economies. Water scarcity and water quality issues are particularly significant in Africa because many African countries have underdeveloped water management systems. Worth noting is that poor water supplies are commonly linked to poverty in these areas. Most water utilised for agricultural purposes across the African continent is primarily obtained from rainfall. For example, some African countries rely on rainfed cultivation accounts, accounting for up to 95% of their agricultural activities. Unfortunately, due to highly irregular and sporadic seasonal rainfalls in Africa, rainfall barely sustains crop management requirements. This results in decreased crop yields and food insecurities in most African countries.
In many parts of the continent, most raindrops evaporate before they can cause run-off. As a result, only a small portion of the rainfall reaches rivers, lakes, and groundwater bodies. Furthermore, most farms are located far from rivers, limiting their ability to use river bodies for irrigation. Notably, the majority of the African continent is made up of deserts and semiarid savannahs. Unfortunately, the majority of these areas receive insufficient surface run-offs of less than 100 millimetres per year. This is too little to support the cultivation of maise, corn, rice, millet, and sorghum, serving as staple foods for most African communities.
Climate change has also changed the rainfall distribution by causing unpredictability to the timing of rainfall per season and has also significantly reduced the amount of rainfall towards drought conditions in recent years. This has a significant impact on the reliability of rainfall, particularly for agricultural purposes. Droughts, for example, are expected to become more common in Africa as a result of climate change and global warming. As shown in figure 1, global warming has gradually contributed to increased and prolonged heat waves, as well as a tripling of droughts in Africa since the 1970s. The slightest increase in global warming poses a significant risk to the continent by increasing heat waves, droughts, and crop failures, exacerbating food insecurity across the continent.
Figure 1: Africa's temperature anomalies, 1920 – 2020 (degrees Celsius)
It is important to note that when crops fail, it is usually due to an extended dry spell during a critical period of the growing cycle, such as the flowering phase, rather than a lack of rainfall. Rainless spells of several weeks are common and can occur at any time of year. However, if they occur at a critical stage of the crop growth cycle, they can have disastrous consequences. During these dry spells, therefore, continuous provision of water irrigation becomes critical.
The limited utilisation of irrigation in Africa and over-dependence on rain-fed agriculture has accounted for the limited agricultural productivity across the continent, among other factors. This is especially true in the continent's rural arid and semiarid areas. Currently, agricultural productivity is highly constrained by variable rainfalls and frequent dry spells. Consequently, this makes rainfed farming a risky undertaking. An estimated 70-85% of the rainfall on African dryland farms is lost through non-productive evaporation, surface run-offs, and deep percolation. Therefore, solutions to manage rainfall water caption and storage, existing water sources, artificial recharge of groundwater, and water treatment should be developed and implemented.
The African Union High-Level Panel on Emerging Technologies(APET) encourages African countries to harness smart technologies and innovations to heighten the management of existing water bodies and exploit rainfall run-offs. To exploit the rainfalls for small-scale farming purposes, APET advises creating more effective water resource capture techniques. This can be accomplished by increasingly focusing on climate-smart technologies to reduce risks from extreme weather patterns due to climate change and global warming. APET recognises that water management should be effective and efficient, especially in rain-fed agriculture. This can be accomplished by pursuing water conservation and management systems through smart water harvesting technologies.
APET advises African countries to adopt green-water measures such as soil and water conservation and harvesting techniques. These techniques are gaining popularity in locations where irrigation is impracticable. Notably, water harvesting involves the collection of rainstorm-generated run-off from a specific region of a catchment to obtain water for human, animal, or crop consumption. For example, surface run-off harvesting and roof-top rainwater gathering are the two most common types of rainwater harvesting practised in Africa. Rainwater that falls on the ground is collected in an underground tank or roof catchment and stored in a tank. The collected water can subsequently be utilised for irrigation purposes. In some cases, the collected water can be stored in above-ground ponds and subterranean reservoirs such as cisterns or shallow aquifers for later use. Water harvesting has been successfully practised in African countries such as Kenya and Tanzania to improve crop yields and food production.
The Green Science for Revolution in Africa and the World Agroforestry Farmers are implementing a water conservation programme in the Nyeri region, Kenya. This programme enhances fruit orchard management after years of declining fruit harvesting due to erratic weather conditions. For example, the use of water harvesting for crop production has enhanced the yields from 1 tonne per hectare to 3–4 tonnes in areas where rain harvesting occurs. Mango and citrus plantations have been enhanced by up to 100,000 Kenyan shillings ($900) per year, a previously unachievable sum. Fundamentally, water harvesting is assisting farmers transition from traditional crop farming to commercial agricultural businesses.
The Majaruba System is progressively being adapted in most surrounding areas due to spontaneous acceptance. The Majaruba Water Harvesting Collecting Method is being utilised in Tanzania as it is allowing farmers to store adequate water and generate yields, especially during periods of low local rainfall. This is enabling irrigation in regions with limited rainfalls and enhances cultivation in previously unproductive lands. Consequently, this has substantially boosted the productivity of household assets and improved rural livelihoods.
However, there is a need for an enabling environment, including profitable marketplaces and the availability of land for agricultural purposes. This has particularly proven to be an important requirement for the system's spontaneous uptake and expansion. Thus, APET encourages African countries to invest in rainwater harvesting infrastructures such as sand, charcoal, sponge filers, ponds, concrete tanks, galvanised tanks and plastic tanks once harvested. This can significantly strengthen water harvesting catchment, harvesting, and storage.
APET notes that using rainwater harvesting technologies to irrigate farming significantly enhances local agricultural activities. More funding, however, is required for African countries to improve rainfed agriculture across the continent. To increase farming productivity, investments in water harvesting infrastructure for smallholder farmers should be pursued. This will assist local farmers in increasing crop production, animal feeding, and farming productivity in order to improve food and nutrition security in accordance with the African Union's Agenda 2063 aspirations.
Kenya has an annual supply of renewable freshwater that is less than 1,000 cubic meters per capita because most farming activities are concentrated in arid and semiarid regions. Farmers who are water-stressed usually wait for the rainy season. This allows for two growing cycles per year for food crops like maise, beans, and sorghum. It is worth noting that Kenya has been experiencing a drought in recent years, resulting in domestic food insecurity. Despite the fact that the situation is gradually improving, several farmers have been gradually adopting water harvesting and storage technologies. This innovation allows rainwater to be stored instead of being drained into rivers that empty into the Indian Ocean. APET recognizes that because rains are infrequent and sometimes insufficient, water harvesting and storage can help farmers generate an adequate harvest.
In Kenya, some farmers growing citrus fruits alongside pulse crops and maise have carved inlets to direct water run-off from the roadside into their gardens. As such, the run-off water can be stored in basins that have been prodded throughout the garden. These basins can be filled with mulch that can absorb and store the water throughout the year. In such cases, the citrus fruits can naturally absorb water from these basins for months after the rainy seasons are long gone. This can also be adapted for growing a variety of pulses, pumpkins, sorghum, and livestock.
APET realises the high cost associated with investing in water harvesting. For example, setting up a water harvesting management system for an 8-acre farm can require an infrastructure that can cost approximately US$2,500, and most African farmers may not afford it. Thus, African countries are challenged to support their farmers as they currently rely on developmental partners for funding.
Furthermore, APET recognises that climate change has shifted the rainfall patterns feeding into rivers and lakes. However, lakes have been shrinking significantly since the 1960s. For example, Lake Chad has been a vital source of water and food for millions of people in Nigeria, Cameroon, Niger, and Chad. In 1963, the lake's surface area was 26 000 square kilometres; today, it is less than 1 500 square kilometres. Regrettably, since chronic droughts' inception in the 1970s, the lake has shrunk by 90 per cent over the last 60 years (see figure 2), resulting in an approximately 60% decline in fish production. The condition has drastically deteriorated due to the region's fluctuating climate, which has increased food and nutritional insecurity. Furthermore, the quality of the surrounding land has also declined, thereby decreasing livestock productivity and biodiversity. This is being experienced by the surrounding Sahel region and across Africa.
Figure 2: The shrinking of Lake Chad from 1963 to 2007
Unfortunately, soil degradation and enormous losses of rainwater from fields occurring through evaporation significantly contribute to the huge yield gaps in crop production. Nonetheless, experimental water-harvesting innovation and precise fertilisation in African countries such as Kenya, Tanzania, Burkina Faso, Niger, and Ethiopia have exhibited the substantial potential to double the agricultural output of smallholder farming. APET recognises that such solutions are essential to enhancing food security and addressing farming challenges, including climate change and land degradation.
Especially in the Sahel region, small-scale farming is becoming unsustainable through conventional farming practices because of declining soil fertility and climatic extremes. There is also progressively decreasing land access due to population pressure, leaving approximately 12 million small-scale farmers persistently susceptible to food and nutrition insecurity. Even during good rainfall, many farmers adopt risky coping mechanisms such as taking on more debt, eating fewer daily meals, and selling their assets. At the same time, scientists have predicted that by 2050, a reduction in agricultural production of millet and sorghum will drop by 13% in Burkina Faso, 25.9% in Mali, and 44.7% in Senegal due to global warming characteristics of climate change. Hence, developing innovation to manage these losses remains crucial for African countries.
Finally, APET challenges African countries to improve their irrigation systems in order to modernize Africa's agriculture and replenish depleting water reserves. Notably, water infrastructure is frequently associated with socioeconomic development, whereas more traditional practices, such as rainwater harvesting, are viewed as backward and inefficient. Similarly, irrigation and excessive blue water extraction can quickly deplete available water sources and have irreversible negative effects on local ecosystems. As a result, Africa's irrigation opportunities remain limited, as rain-fed agriculture accounts for 95 percent of Africa's food production. Simultaneously, only 5.5 percent of arable land is suitable for irrigation due to limited water availability and accompanying landscape topographies that make irrigation difficult and costly. Africa contains roughly 60% of the world's uncultivated arable land, and much of it remains uncultivated. Climate-smart innovations and technologies, on the other hand, may present opportunities for enabling farming in these lands. As a result, African countries must improve water management techniques in order to conserve and store water for African farmers.
 Emma Archer, Willem Landman, Johan Malherbe, Mark Tadross, Simone Pretorius, South Africa’s winter rainfall region drought: A region in transition?, Climate Risk Management, 25, 2019, 100188, ISSN 2212-0963, https://doi.org/10.1016/j.crm.2019.100188.
 D. Hillel, WATER HARVESTING, Editor(s): Daniel Hillel, Encyclopaedia of Soils in the Environment, Elsevier, 2005, Pages 264-270, ISBN 9780123485304, https://doi.org/10.1016/B0-12-348530-4/00306-4.
 Nyamadzawo, G., Wuta, M., Nyamangara, J., & Gumbo, D. (2013). Opportunities for optimization of in-field water harvesting to cope with changing climate in semi-arid smallholder farming areas of Zimbabwe. SpringerPlus, 2(1), 100. https://doi.org/10.1186/2193-1801-2-100.
 Fox, Patrick & Rockström, Johan & Barron, Jennie. (2005). Risk analysis and economic viability of water harvesting for supplemental irrigation in semi-arid Burkina Faso and Kenya. Agricultural Systems. 83. 231-250. 10.1016/j.agsy.2004.04.002.