STREAM DlVERSION IN THE EAST AFRICAN RIFT VALLEY
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CTA. 1995. STREAM DlVERSION IN THE EAST AFRICAN RIFT VALLEY . Spore 57. CTA, Wageningen, The Netherlands.
Permanent link to cite or share this item: http://hdl.handle.net/10568/47066
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High above the Kerio Valley on the western escarpment of Kenya's Rift Valley live the Marakwet. They grow cereals, principally finger millet and sorghum, and combine this with pastoralism, the women cultivating the crops and the men herding the...
High above the Kerio Valley on the western escarpment of Kenya's Rift Valley live the Marakwet. They grow cereals, principally finger millet and sorghum, and combine this with pastoralism, the women cultivating the crops and the men herding the animals. Cereals are grown on the floor of the Kerio valley and on the slopes of the escarpment and, since rainfall is insufficient to guarantee the crop, the Marakwet make use of the water that nuns down the escarpment in small but torrential streams, draining the wet highlands of the Cherangani plateau above. Dams made from brushwood, stones and logs are built longitudinally in these streams diverting the water into irrigation channels of stones and mud which carry the water along, and gradually down, the escarpment to the valley below. Controlling the descent of the water requires considerable technical engineering. The total length of furrows on the Marakwet escarpment is very large and, at one time, there were 40 main furrows totalling 250km in length in one 40km stretch of escarpment. Log aqueducts are used to carry water over streams and other channels; where there are sheer cliff faces, stone revested terraces and sluices are constructed. These days, many of the furrows are repaired or rebuilt with cement or other modern materials. Maintenance, which has traditionally been carried out by the men, seems to be effective, although continued regular maintenance may be at risk as young men move away from the area to find work. Many features of the Marakwet irrigation are repeated elsewhere. On the slopes of Mt. Kilimanjaro in Tanzania the Chagga have long irrigated coffee and bananas as well as maize, pulses and finger millet, and their canals also serve an important purpose in domestic water supply. On the west side of Lake Natron in northern Tanzania, the Sonjo people also practise hill furrow irrigation. Some villages make use of water flowing from springs while others divert water from a nearby river with 3m high brushwood dams. Although concrete is occasionally used in some of the head-works, the canals themselves are simply cut into the ground and water is released from these earthen canals to flood across the surface of the fields. However, water rights are closely defined and there is a clear cycle of water use and system of water allocation. As a result, water use is carefully managed.
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