Analysis of factors determining sediment yield variability in the highlands of northern Ethiopia

In many developing countries, sustainable land management and water resources development are threatened by soil erosion and sediment-related problems. In response to such threats, there is an urgent need for improved catchment-based erosion control and sediment management strategies. The design and implementation of such strategies require data on erosion rates and understanding of the factors that control the delivery of sediment through the catchment system. In this study, reservoir sedimentation and corresponding catchment attribute data were used to investigate the major factors controlling sediment yield variability in a mountainous dryland region of northern Ethiopia. Sediment yield data were acquired for representative 11 catchments above reservoirs. Geomorphological and anthropogenic catchment attributes were extracted for each reservoir from different sources including digital elevation models, satellite images and field surveys. Different statistical analyses such as Pearsonʹs correlation, principal components and multiple regression were implemented to analyze the relationship between sediment yield and catchment characteristics and to determine the major factors controlling the variability of sediment yield. The results show that terrain form, gully erosion, surface lithology, and land cover explain most of the variability in sediment yield among the catchments. The implications of the results, for relevant management intervention targeted at ameliorating the major causative factors of erosion, are also outlined.