The Amba Landscape of the Ethiopian Highlands, Shaped by Rockfall

摘要: Cliff retreat occurs on the ambas or structurally determined stepped mountains of northern Ethiopian highlands. This chapter describes rock fragment detachment from cliffs by rockfall, quantifies its annual rate and identifies factors controlling movement scree slopes. It further presents a conceptual model explaining cover at soil surface in these landscapes. In May Zegzeg catchment (Dogu’a Tembien district, Tigray), rockfall debris slopes run-off livestock trampling were monitored over 4-year period (1998–2001). Rockfall transport mainly induced appear to be important geomorphic processes. Along 1500 m long section Amba Aradam sandstone cliff, least 80 t rocks are detached yearly fall mean vertical distance 24 resulting cliff 0.37 mm year−1. Yearly unit rates ranged between 23.1 37.9 kg m−1 process is virtually stopped when exclosures established. A indicates that besides argillipedoturbation, all processes redistribution study area anthropogenic origin.