Retaining scarce resources - rainwater harvesting in Sudan
Northern Darfur state, one of the most drought prone areas of Sudan, is situated on the edge of the Sahara desert. Precipitation is concentrated in the short summer period, but rainfall is becoming increasingly erratic and unreliable, so that farmers cannot rely on the amount of rain or where it will fall. Even heavy storms, which occur once or twice a year, can cause problems - by washing away topsoil Retaining scarce resources - rainwater harvesting in Sudanand reducing the land’s fertility - rather than providing relief. The result has been great loss of livestock, crops, natural vegetation and wildlife, undermining the sustainability of rural livelihoods.“ Climate change has led to more extreme weather, increasing both the occurrence of droughts and floods.
It is disrupting the world’s rainfall patterns, making it difficult for farmers to plan for crop and livestock production,” explains Practical Action’s agriculture advisor, Hilary Warburton. “In sub-Saharan Africa, 90 per cent of agriculture is rain-fed, making it even more vulnerable to changing weather patterns. Technologies for harvesting rainwater, which are low-cost and locally-managed, are a great way of maximising the use of infrequent rainfall.”
In Northern Darfur, farmers and livestock keepers have many ways of coping with arid conditions including use of man-made reservoirs, known as hafirs, to capturerainwater, and low terraces to prevent run-off and increase water conservation, but the changing conditions are very challenging. Practical Action is working with farmers to help them build on their existing knowledge and skills to solve current water problems. “In this region this approach is more cost-effective, appropriate and sustainable over the long-term than imposing expensive solutions such as large irrigation systems or solar pumps,” Warburton adds.
Sustaining rural livelihoods
Practical Action has focused on involving local communities in retaining scarce rain for irrigating their land and diversifying their crops. Farmers have been shown how earth embankments can be built to allow more of the run-off to be retained in the soil when it rains, enabling it to be cultivated with staple crops like sorghum, millet and vegetables.
Shallow wells and hafirs have also been dug and channels and troughs added so that animals no longer walk into the water and so it remains usable for humans.
An investigation found that 80 per cent of the land in wadi areas (depressions with heavier soil) was not being exploited, despite its high fertility, as the wadis are difficult to work with existing tools and technologies. And those farmers who were cultivating the land were building traditional rectangular terraces that had no drainage or ditch system and failed to follow the contours. As a result, farmers did not make the most of the rain when it came and wasted crops and water when they were washed away by the strength of the storm.
To compare the use of crescent-shaped terraces against traditional terraces, a demonstration farm was set up by 25 farmers in Azagarfa. All the necessary equipment and tools were produced locally and 900 volunteer farmers - men and women - were trained in how to lay out and construct a crescent-shaped terrace. The demonstration showed that crescent terraces were more flood resistant, retained water more effectively, provided far better crop yields and provided a water source for families and animals. For example, sorghum production was 4 tonnesper hectare on average, compared with 1.4 tonnes in similar rainy seasons using traditional terraces. Even in drought years, crop yields were at near average levels.
By providing technical support and some materials, Practical Action has also helped local people to rebuild and strengthen a number of dams by providing the concrete needed to build walls. Water caught and retained by the dams has helped to irrigate the surrounding land for plant cultivation, providing vegetables for improved nutrition, fodder for animals, and cash crops, including watermelon and vegetables. An assessment of the Shangil Tobaya dam project indicates that cultivated land increased eleven-fold to 6,060 hectares as a result, benefiting more than twice the number of families.
“Compared with investments in other technologies, such as new drought-tolerant seeds or large irrigation systems, rainwater harvesting has many advantages,” Warburton reasons. “It makes best use of scarce water resources, does not deplete aquifers and can prevent flood damage and soil erosion through capturing run-off. Rain water harvesting systems are developed to match the ecosystem in which they operate and use local skills and materials.”
The Sudanese team has been working as a facilitator with the state government and farming communities to encourage better support for the development and maintenance of hafirs and dams in the future. By demonstrating the potential of these approaches as part of the government’s agricultural strategy, and showing that they are affordable, effective and manageable by the local community, Practical Action hopes that there will be a long-term improvement to the ability of communities in Darfur to cope with a future made uncertain by climate change.
“In many ways, rain water harvesting is an often overlooked solution: certainly if as much money was invested into it as other technologies, we would be able to transform the lives of many more people,” Warburton concludes.
SourceThe Global Forum on Agricultural Research