By Esther Ngumbi and Sam Dindi
After a prolonged drought season, many African countries are now grappling with heavy rains and floods. The excess water flow is damaging infrastructure and causing deaths, hurting these countries’ economies in the process. In Rwanda and Uganda, for example, recent floods have destroyed 924 homes, wiped out a hospital that cost $11.3 million to build, and ruined over 140 hectares of crops. In Kenya, recent floods have left at least 15 dead and destroyed property worth millions. In Tanzania, annual damages related to floods are estimated at $2 billion. And in 2017, according to the World Bank, floods cost Sierra Leone’s economy $30 million.
Around the world, climate change is linked to the increased frequency of extreme weather events. In 2017, for example, disasters including floods, heat waves, and wildfires caused at least $306 billion in damage. These figures are expected to continue rising. By 2050, flooding may cause more than $1 trillion in destruction worldwide.
The irony is that many of the countries experiencing floods and heavy rains are the same ones that experience seasons of drought and hunger. Less than a month ago, Rwanda was delivering food to citizens amid a prolonged drought. And in 2017, over 10 million Ugandans struggled with hunger. Citizens of many other African countries, including Kenya and Tanzania, had similar experiences. This trend is not new; every year, headlines about drought and hunger in Africa appear in news. But during the rainy season, water wastes away instead of being harvested for use during periods of extreme heat. Floodwaters are left to evaporate or flow into lakes or the ocean, rather than be put to use to support agriculture and industry, supply drinking water to both humans and wildlife, generate power, and provide recreation.
There is a clear need to bridge this gap. In African countries affected by extreme weather, there’s an incentive to devise innovative tools, technologies, and practices to collect and store floodwater. Doing so can help Africa to meet its food security needs, too: Sustainable crop production requires a consistent supply of water to make up the difference when the rains fail.
Across the continent, communities have employed new methods of harvesting rainwater, but these practices have not yet been widely adopted due to the high cost of the resources and technologies involved. For example, in Rwanda, the expense of rainwater-harvesting tanks has prevented many citizens from storing water. A 5,000-liter water tank costs up to $500, while a 10,000-liter tank can cost $1,000.
Farmers and herders are using trapezoidal bunds and water pans to preserve rainwater for human and livestock consumption and to irrigate crops when drought strikes. Trapezoidal bunds, which consist of long ridges (bunds) of earth constructed on a hill in the shape of a trapezoid, catch rainwater as it flows down the hill. Water pans—small water reservoirs created by excavating open ground—capture and store surface runoff from uncultivated land, hillsides, roads, rocky areas, and open rangelands. These systems, both recommended by the U.N. Food and Agriculture Organization, have been successfully tested in Turkana County, Kenya, where locals collected water from flash floods and used it to produce fruits, vegetables, and sorghum (a source of grain). Other methods that are just as simple to implement include water ponds (small excavated depressions), water tanks (containers made from plastic, fiberglass, or concrete), land-based dams (a barrier that holds and restricts the flow of water), and rock catchment systems (developed from a rock outcrop to catch and store rainwater runoff).
African countries ought to invest in local and national government initiatives on a larger scale, as well as prioritize the rehabilitation of lakes and wetlands. These bodies of water can serve as giant dams, reducing the amount of water lost as runoff and preventing flash floods, which destroy property and take lives. According to a U.N. report, the amount of rainwater that could be captured in countries like Kenya and Ethiopia, both of which are affected by drought and food insecurity, would far exceed the needs of their current populations.
Technology can also help communities prepare for the rainy season. Early warning and practical advice can save lives and minimize the economic damage caused by floods and other climate-related disasters. In Mozambique, for example, a mobile phone app was developed to help farmers make the most out of rainwater harvesting. Farmers simply enter a few parameters, including their location and the type of roof on their buildings, and then the software determines how much water can be harvested each day or month. The app further advises on harvesting methods and the equipment needed to best collect and safely store rainwater. Furthermore, to help prepare Africa for floods and droughts, the U.N. Office for Disaster Risk Reduction teamed up with the Italy-based CIMA Research Foundation to create drought and flood risk profiles for 16 African countries. Armed with this knowledge, African countries can better prepare and launch effective programs.
Recognizing the importance of this issue, many African countries are taking steps to make rainwater-harvesting practices more widespread. Last year, the government of Kenya launched a national chapter of the Billion Dollar Alliance for Rainwater Harvesting, an initiative involving multiple international organizations that aims to expand across the continent. The Kenya chapter plans to construct 1 million water ponds. The water collected and stored will be used to support agribusiness and dryland farming, a farming practice in arid regions that minimizes water usage. Rwanda’s Natural Resources Authority, a government agency, also launched a program in one county that installed more than 4,000 water tanks to harvest rainwater.
Government efforts have been complemented by projects launched by NGOs and other stakeholders. In Kenya for example, the African Water Bank, an international nonprofit, rolled out an initiative that will harvest and store water on a large scale. The plan is to build concrete water tanks with the capacity to collect up to 600,000 liters (more than 150,000 gallons) of water in just two to three hours of steady rain. The stored water can serve a community of 400 people for two years, and will be distributed in areas often affected by drought. In Sierra Leone, the United States Embassy rolled out a similar water-harvesting initiative.
These developments are positive, but much more is needed to make a real difference. Less than 5 percent of the Africa’s rainwater is harvested and stored for future uses. Capturing even this amount of rainwater provides many people with multiple gallons for consumption and agriculture during prolonged droughts, but at the same time, the rainwater-harvesting initiatives currently in place serve only a fraction of Africa’s 1.2 billion citizens. African nations need to ensure that no further rainwater goes to waste.
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Esther Ngumbi is a distinguished postdoctoral researcher at University of Illinois at Urbana Champaign Entomology Department and a food security fellow with Aspen Institute’s New Voices Fellowship.
Sam Dindi works in the field of tourism and wildlife management in Kenya.[Photo courtesy of Oxfam East Africa]