ESTIMATING THE RATE AND CONSEQUENCES OF GULLY DEVELOPMENT, A CASE STUDY OF UMBULO CATCHMENT IN SOUTHERN ETHIOPIA

In southern Ethiopia wide and deep gullies are common features, significantly affecting farmers' livelihoods. Little action is being taken to address the problem despite farmers being knowledgeable about erosion and its control measures. A study was conduced to investigate the nature and rate of gully development in Umbulo catchment, southern Ethiopia, based on interviews with farmers and field measurements. The results indicated a rapid. down slope development of gullies over the last 30 years with average rate of soil loss from 11 to 30 tha(-1) y(-1). The critical period of development of the gully system was estimated to be between 1974 and 1985. but since then the gully system has enlarged both in depth and width. Wide channels with deep, nearly vertical walls are typical. The trigger for (gully initiation is believed to have been human. but the soil properties may have played an important role. Under the current situation agricultural production is unsustainable unless the gullies are controlled using integrated measures at the catchment scale. Copyright (c) 2008 John Wiley & Sons. Ltd.