Water and food: will a Green Revolution bring falling water tables to Africa?

To feed the growing global population, food production must be greatly increased. Economists have suggested that food shortages could be alleviated by an agricultural revolution in Africa but what might this mean for Africa’s groundwater? Vincent Casey, WaterAid’s Technical Support Manager – Water Security, explores the question.


27 Feb 2015

For thousands of years, irrigation has helped people to increase agricultural production and keep pace with rising food demand. Towards the mid-1900s, advances in diesel-powered pumping technology enabled farmers to draw water from aquifers deep underground. However, in some parts of India, China, the Middle East and the USA, water is pumped out and used for irrigation faster than it is replenished by rainfall and groundwater recharge.

This over-pumping threatens the future of food production in these areas, with possible global consequences. A water security crisis, due to unsustainable water use, could manifest as a food security crisis, in the form of decreased agricultural output.

Food production is likely to flatline in developed grain producing nations. A UN Food and Agriculture Organization report – How to feed the world by 2050 – claims that, for global food needs to be met, global food production must increase 70% by 2050. The report calls for an increase of at least 60% in investment in developing country agriculture to accomplish this.

Africa’s food deficit

Although irrigation has been practised along West Africa’s Niger river for more than 3,000 years, Sub-Saharan African food production is almost entirely rain-fed. Only about 6% of Africa’s cultivated land area is kitted out for irrigation, compared with 37% in Asia and 14% in Latin America. Much of the irrigation is around rivers and dams in Egypt, Madagascar, Morocco, South Africa and Sudan.

In an Economist blog entitled How to feed the planet: why the world needs an agricultural revolution in Africa a chart using data from global food producer Cargill showed food surpluses and deficits across different continents, illustrating a severe deficit in Africa and the Middle East.

The chart not only highlights that Africa does not produce sufficient food for its current population of 1.1 billion – it also raises alarming questions about food provision for its predicted 2050 population of 2.4 billion. To feed its people, the continent must increase its agricultural output to turn this deficit into sufficiency or surplus.

What would increased agricultural production mean for Africa’s groundwater?

An irrigated maize plantation in Kenya(Left: An irrigated maize plantation in Kenya. Photo: WaterAid/Vincent Casey)

Continued agricultural development and increased food production in Africa are very much in its interests, and the resulting economic benefits could help to lift people out of poverty. An International Food Policy Research Institute report estimates that irrigation could boost agricultural productivity in Africa by 50%. But what would this mean for Africa’s groundwater?

A direct relationship exists between the amount of crop biomass produced and the amount of water taken up by a crop and lost to the atmosphere through its leaves. Increased food production in Africa would therefore mean increased water consumption provided that water taken up by crops and transferred to the atmosphere was not immediately re-precipitated back into the catchment from where it came.

Despite the relatively low use of irrigation on the continent, there are growing concerns about unsustainable groundwater abstraction for food production in areas where groundwater-based irrigation is practised, for example, in parts of Southern Africa.

If we look at India’s ‘Green Revolution’ which began in the 1960s, some of the drivers that have caused severe groundwater overdraft could be emulated in parts of Africa. For example, weak regulation of groundwater extraction and poor water supply service delivery from public authorities are already realities that could incentivise farmers to develop private wells, which are difficult to restrain. Water ownership has not generally been de-linked from land ownership, further weakening potential for effective regulatory control of abstraction.

I am speculating here, but if improved rural electrification were to arise, it could bring the prospect of politically motivated energy subsidies, shielding farmers from the true cost of pumping, and encouraging greater use of groundwater. Similarly if cheaper pumping technologies were to become available, they could facilitate more widespread pumping from greater depths.

Currently, groundwater development for irrigation tends to be constrained by the capacity of farmers to access and use high output pumps rather than geology or a shortage of groundwater itself. Indeed, in some areas, a drive towards increased commercial food production may not be manifesting itself as increased groundwater abstraction but rather as increased securitisation or ‘grabbing’ of land.

Will Africa’s geology constrain groundwater overuse?

According to the British Geological Survey, roughly 50% of Sub-Saharan Africa’s population lives on crystalline basement geology, where groundwater occurs in fractures and weathered pockets, and therefore cannot be found everywhere. This geology is characterised by highly variable borehole yields. The amount of water that can be obtained from a borehole in the long-term depends on the amount of water storage available in the aquifer, the rate at which water can move through the aquifer into the borehole, the rate at which the aquifer is recharged by rainfall, and demands on the aquifer from other users. All of these factors vary over short distances, meaning the high borehole yields needed for irrigation cannot be found everywhere.

Limitations on irrigation potential may mean that efforts to improve agricultural productivity might have to focus on a better, more nuanced understanding of rain-fed techniques and soil water infiltration, as well as groundwater pumping. An increased use of soil water will still have knock on implications for groundwater recharge and therefore water availability.

What impact might increased groundwater development have on WASH services?

A farmer primes a petrol operated low-lift groundwater pump used for irrigation in the River Yobe flood plain of North East Nigeria(Left: A farmer primes a petrol operated low-lift groundwater pump used for irrigation in the River Yobe flood plain of North East Nigeria. 
Photo: WaterAid/Richard Carter)

Rural water, sanitation and hygiene (WASH) programmes that focus on providing relatively small quantities of water for domestic supply and small-scale livelihoods also tap into crystalline basement aquifers. Irrigators and increased use of soil water could begin to have an impact on WASH programmes, as they have done in parts of India. The WASH sector in India has generally struggled to respond to this issue, but some programmes (including those implemented by WaterAid) have successfully zoned off pockets of groundwater for domestic abstraction. This can only be done in aquifers where groundwater drawdown over large areas is not possible.

There is a question over how ready the WASH sector is for a possible exponential increase in water consumption. When new WASH water supply services are initiated, investigations into the available water are generally limited to a three hour borehole pumping test. This reveals nothing about aquifer storage or recharge. In other words, it reveals nothing about how much water is likely to be available for different uses over time. A greater appraisal of water, livelihood and food security related threats will be necessary in government and NGO WASH programmes of the future, with more emphasis on the critical role of ongoing hydrological monitoring to better understand water availability and quality for all water uses.

Greater coordination between the WASH and ‘big water’ commercial food production sectors will also be required. As a WASH practitioner, I am aware that these two sectors have not interacted much because they depend on very different methods of service provision. WASH services are needed close to people’s homes, whereas water for food is needed in the fields where crops are. The WASH sector depends on relatively small volumes of high-quality water, whereas the agricultural sector needs large volumes, and microbiological water quality is not such an issue.

Despite these differences in programming, there are many overlaps between the activities of the WASH and water for food sectors. Both work in support of greater food security. Water points introduced as part of WASH programmes are often the only sources accessible in times of drought, providing vital water supplies for small-scale household food production. WASH services defend against certain debilitating illnesses, promoting better bodily uptake of nutrients and more time to work in the fields growing food. Some WASH programmes promote soil nutrient recycling through deployment of composting toilets with positive impacts on food production. Higher household incomes from the sale of crops can potentially be reinvested in keeping water supply services running.

These positive links can be used as an entry point for greater coordination with big water users in an attempt to get a more joined up approach for the assessment of water-related risks and mitigating steps to avoid groundwater depletion. A Multiple Use Services (MUS) approach to water supply service delivery can help.

Certainly, a possible future irrigation explosion raises issues for groundwater resources in Africa. But of equal and perhaps more immediate concern is the rapid growth of small towns, which increasingly need to use intensive groundwater pumping to service piped distribution networks. A small town of just 10,000 people has a daily water consumption similar to that of a 20 hectare irrigated plot in Africa. Without better hydrological monitoring, the effective management of both urban and rural water demands will prove to be difficult in the future.

Vincent Casey is WaterAid’s Technical Support Manager – Water Security. You can read more of his work for WaterAid here >

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