Wetenschap - 22 maart 2001

Improving traditional irrigation in Eritrea

Improving traditional irrigation in Eritrea

During the rainy season in Eritrea, large amounts of water flow down from the highland areas through the beds of a number of wadis. Fifty one million cubic metres of water flow through each year, of which the greatest amount comes within a period of six hours. One moment the river is dry, the next moment a huge quantity of water passes through.

Farmers in the low lying area of Sheeb near the Red Sea coast use the sudden amounts of water to irrigate their land in a system known as spate irrigation. After being diverted, the water sinks into the deep soil and provides the crops, sorghum and maize, with moisture for the rest of the growing season. The problem is that the water sometimes flows with such a force that the dams in the wadi (agim), which are used to divert the water to the fields, are regularly washed away.

Participatory approach

PhD candidate Mehreteab Tesfai Hadera points out the advantages to the system: yields are relatively high without the use of artificial fertilisers. This is because the water itself carries fertile sediment, which is deposited on the fields. Tesfai used a Participatory Rural Appraisal approach to examine ways to make the system more sustainable. Farmers have been making dams in the wadis for hundreds of years. They use tree trunks and branches, strengthened with earth. If the dams are big enough and the water flow is not too strong they hold up. But this is often not the case, and then water is lost. In addition, the use of trees and shrubs is leading to serious deforestation.

Tesfai suggests in his PhD that the traditional dams be replaced by more permanent concrete structures. In this way more water can be caught and less will be lost if it is channelled through concrete-lined canals. Maintenance will also be less labour intensive, which will leave the farmers more time to cultivate crops, thus also possibly increasing yields.

Project

The Eritrean ministry of agriculture has received World Bank funds to build permanent flood diversion structures for spate irrigation. "Farmers will have ownership in the programme and will be responsible for construction and maintenance of the system," Tesfai explains. The project was held up by the war between Eritrea and Ethiopia, but the ministry now wants to restart the project.

Mehreteab Tesfai Hadera received his PhD on Tuesday 20 March. He was supervised by Professor Leo Stroosnijder, of the Erosion and Soil and Water Conservation Group at Wageningen University.

Joris Tielens

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