Assessment of current land use and potential soil and water conservation measures on surface run-off and sediment yield

Soil erosion has accelerated in most regions of the world, especially in developing countries, due to various socio-economic and demographic factors and limited expertise (Bayramin et al., 2002). Geographically, soil erosion is more severe in the tropical highland areas and less severe in the temperate regions of the world (Barrow, 1991). This implies that many of the developing countries are located in the former geographic regions. In Ethiopia, one of the poorest countries in the world, soil erosion by water contributes significantly to the food insecurity of rural households and constitutes a real threat to sustainability of the existing subsistence agriculture (Hurni, 1993; Sutcliffe, 1993; Sonneveld, 2002). Ethiopia has a total surface area of 111.8 million hectares, of which 60 million hectares are estimated to be agriculturally productive. Twenty-seven million hectares are significantly impacted by erosion, 14 million hectares are seriously eroded and 2 million hectares have reached the point of no return. Studies by Fikru (1990) and Sertsu (2000) estimate an annual total soil loss of 2 billion m3. In the Ethiopian highlands, annual soil loss reaches rates up to 200-300 tons per hectare, while soil loss movement can reach 23,400 million tons per annum (FAO, 1986; Hurni, 1993). Despite the general awareness in Ethiopia, spatially and temporally detailed information on surface run-off and soil loss is rather limited.