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If being one of the driest continents of the world – with many countries struggling with widespread hunger and poverty – does not sound challenging enough, try throwing a fourfold increase of the population size into the mix. Not to mention that the water supplies for cities and food production have not been secured.
If things stay on their current trajectory, this is exactly what Sub-Saharan Africa will be facing during the remainder of this century.
Since past literature has been dominated by western views based on very different climates that the hot-and-dry one that dominates this region, centre researcher Malin Falkenmark argues that a shift in water thinking is needed to meet these major challenges. In a chapter in a new book called Assessing Global Water Megatrends, she guides us through the situation, its challenges, and opportunities:
This paper explains why conventional solutions addressing poverty and hunger used in Asia, relying on runoff water for irrigation, will not work in the vast dryland parts of Africa. Instead, direct management of scarce rainfall will have to be develop into an integral part of the development agenda within an African Blue-Green Water Revolution.
The African continent is dominated by drylands, characterized by scarce and unreliable rainfall, extremely high potential evaporation, and poor abilities of the soil to retain water. The majority of the year is marked by the unproductive dry season. When rain eventually falls, much of it evaporates before even reaching a river. Crop yields in these parts are low, and they seem stuck in a loop of poverty and hunger. With climate change, the rain seasons become increasingly unreliable, and much harvest is lost due to prolonged dry spells.
More regular rainfall is mainly concentrated to local mountains, which due to their elevated position works as water towers, channelling the water into some a few major transnational rivers corridors. Because of this, the presence of blue water (i.e. liquid fresh water found in reservoirs such as streams, lakes, and groundwater) is very local in the drylands.
The already difficult situation with trying to feed the population will be much exacerbated by the current population explosion. Projections are that the population size will be increased fourfold before the end of this century, largely due to growing life expectancy. Urbanisation rates are among the highest in the world, indicating that most of this increase will populate large cities. This will put an enormous pressure on the currently unsecured raw water supplies for the megacities.
Clearly, models fitted for a more humid climate is not going to do the trick in these parts. Instead, the hydroclimatic reality of the region needs to be incorporated into the management policies and practices in order to meet the challenges.
Because of the local nature of blue water, Falkenmark argues that these sources are best suited for securing raw water supplies for cities. This requires international collaboration and water management since the larger rivers are transnational.
Since the blue water is – except for local wells - out of reach for most farmers, food production is basically reliant on green water (i.e. water in precipitation, evaporation, and retained in soil). Today, up some 70 % of the rainwater is lost through evaporation, runoff and drainage. The key here, Falkenmark argues, is to start viewing these huge water losses as a resource. By preparing the soil for increased water infiltration, surface runoff could be reduced, and local harvest of rain and runoff water, could allow for supplementary irrigation to prevent lost yield during dry spells.
Sub-Saharan Africa faces complex challenges related to water and population size, but with the right mind-set, a lot can be done to meet them. But this requires close attention by decision makers. As Falkenmark puts it:
“And there exists, in fact, encouraging experience in other water short regions of the world, where water shortage challenges have been possible to overcome. Of fundamental importance for success is, however, that politicians become rapidly aware of Africa’s Achilles’ heel, the great vulnerability that it involves, and the extreme urgency of adequate action, both as regards water supply of rapidly growing cities, and safe and rapid smallholder agricultural development.”
Falkenmark, M. 2018. Shift in Water Thinking Crucial for Sub-Saharan Africa’s Future. In: Asit K. Biswas, Cecilia Tortajada, Philippe Rohner (Eds.) Assessing Global Water Megatrends. Springer, Singapore. DOI: https://doi.org/10.1007/978-981-10-6695-5
Malin Falkenmark is a senior researcher focusing on green water, ecohydrology, hydrosolidarity and water resilience. She is considered one of the world's most prominent scientists on sustainable water mangement.
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