Water and Food: a focus on Africa

Following the challenges triggered by climate change that were discussed last week and addressed at the Conference of the Parties that just concluded, this post aims to assess the potential fields for improvement that will facilitate adaptation to water and food stressors. Africa indeed hosts significant adaptation capacity, but it requires an impulse in its development. The post will be particularly dedicated to two adaptation themes, water storage and crop adaptations. The  International Water Management Institute (2009)  recognises that policies aiming to improve citizen access to water would be most effective if they invested in storage facilities or community-managed irrigation systems intended to overcome droughts among other communal strategies. However, despite the potential success of such policies, scepticism derives from their capacity to generate conflict and divert investments for maladaptation strategies ( Vermeulen et al., 2012 ). This raises great concern, as it is a pr

Early 21st Century projections ascribed the greatest rates of water withdrawals to Africa ( Arnell et al., 2001 ). However, these did not account for withdrawals under a changing climate which may increase rainfall. The adverse climate change impacts exacerbate threats to African food insecurity, particularly given the continent's hydrological requirements and limited coping mechanisms ( Niang et al., 2014 ). Climate resilience and water and sanitation are and will continue to be essential themes for sustainable development.  Changing inflows to endorheic lakes, like Tanganyika or Malawi, can have substantial effects, already observed in the Aral Sea or in the Great Salt Lake. Single short-term increases in inflows to exoreic lakes, such as Lake Victoria, have been seen to cause rising levels over several years ( Arnell et al., 2001 ). Consequences could offset the nutrient balance and affect the trophic chain. Direct anthropogenic impacts such as overfishing, pollution and introdu

Irrigation schemes are not even slightly innovative. Shadufs and Archimedean screws dating back to 5,100BP are documented in Ancient Egypt. Qanats existed in the Middle East and North Africa since 600BC. Many other examples populate Africa as well as in Asia and Europe. Onto the 21st Century, 20% of the world’s croplands are irrigated and generate 40% of the global harvest ( Khan et al., 2006 ). As concerns for food security in Africa increase under rapid population growth, irrigation is programmed to seize an increasing share of the water supplies. The continent holds great potential for expansion of irrigated agriculture. However, poorly managed systems are unfortunately common and are associated to waterlogging and pollution, which causes the reduction of productivity ( Khan et al., 2006 ).                            Farmer using a shaduf to irrigate fields, picture taken after a painting at tomb of Ipi at Thebes Deir el-Medina, 19th dynasty, c. 1292-1190 BC ( Gianni Dagli Orti, 197

Irrigated vegetable fields in Ethiopia (Ejeta, 2019) Malin Falkenmark developed the Water Stress Index (WSI) following the famines impacting Africa in the 1980s. The indicator calculated improved water supplies able to provide self-sufficient crop production relative to the portion of the population jointly depending on each flow unit of water available to the country from the water cycle ( Falkenmark, 1989 ). It classified different categories of water access, defining absolute water scarcity as 1000 people depending on 1,000,000m3/year (i.e. single flow unit of water).  Falkenmark (1989 ) did recognise the added complications of interannual fluctuations, but the index bears other limitations. The WSI along with other holistic water metrics, defines freshwater resources in terms of Mean Annual River Runoff (MARR), which denies variation of freshwater quantities in groundwater, lakes, dams and reservoirs ( Damkjaer and Taylor, 2017 ). Moreover, intra-annual variations mask scarcity and