African countries suffering or facing water shortages as a result of climate change have a massive potential in rainwater harvesting, with nations like Ethiopia and Kenya capable of meeting the needs of six to seven times their current populations, according to a United Nations report released today.
“The figures are astonishing and will surprise many,” UN Environment Programme (UNEP) Executive Director Achim Steiner said of the study, compiled by his agency and the World Agroforestry Centre, which urges governments and donors to invest more widely in a technology that is low cost, simple to deploy and maintain, and able to transform the lives of households, communities and countries Africa-wide.
Overall the quantity of rain falling across the continent is equivalent to the needs of 9 billion people, one and half times the current global population. About a third of Africa is deemed suitable for rainwater harvesting if a threshold of 200 millimetres of arrival rainfall, considered to be at the lower end of the scale, is used.
Although not all rainfall can or should be harvested for drinking and agricultural uses, with over a third needed to sustain the wider environment including forests, grasslands and healthy river flows, the harvesting potential is still much more than adequate to meet a significant slice of human needs, the report notes.
“Africa is not water scarce,” it concludes. “The rainfall contribution is more than adequate to meet the needs of the current population several times over. For example Kenya would not be categorized as a ‘water stressed country’ if rainwater harvesting is considered. The water crisis in Africa is more of an economic problem from lack of investment, and not a matter of physical scarcity.”
Until recently the importance of such harvesting as a buffer against climate-linked extreme weather has been almost invisible in water planning with countries relying almost exclusively on rivers and underground supplies, the report notes.
Unlike big dams, which collect and store water over large areas, small-scale rainwater harvesting projects lose less water to evaporation because the rain or run-off is collected locally and can be stored in a variety of ways.
“Over the coming years we are going to need a range of measures and technologies to capture water and bolster supplies,” Mr. Steiner said. “Conserving and rehabilitating lakes, wetlands and other freshwater ecosystems will be vital and big dams, if sensibly and sustainably designed and constructed, may be part of the equation too.
“However, large-scale infrastructure can often by-pass the needs of poor and dispersed populations. Widely deployed, rainwater harvesting can act as a buffer against drought events for these people while also significantly supplementing supplies in cities and areas connected to the water grid,” he added.
The report mapped the rainwater harvesting potential of nine countries in Africa –Botswana, Ethiopia, Kenya, Malawi, Mozambique, Uganda, Tanzania, Zambia, and Zimbabwe.
Kenya, with a population of somewhere under 40 million people, has enough rainfall to supply the needs of six to seven times its current population, according to the study. Ethiopia, where just over a fifth of the population is covered by domestic water supply and an estimated 46 per cent of the population suffer hunger, has a potential rainwater harvest equivalent to the needs of over 520 million people.