High-resolution digital elevation models and orthomosaics generated from historical aerial photographs (since the 1960s) of the Bale Mountains in Ethiopia

Abstract. The natural resources of Ethiopian high-altitude ecosystems are commonly perceived as increasingly threatened by devastating land-use practices owing to decreasing lowland resources. Quantified time-series data of the course of land-use cover changes are still needed. Very high-resolution digital data on the historical landscape over the recent decades are needed for determining the impacts of changes in afro-alpine ecosystems. However, digital elevation models (DEMs) and orthomosaics do not exist for most afro-alpine ecosystems of Africa. We processed the only available and oldest historical aerial photographs for Ethiopia and, to the best of our knowledge, for any afro-alpine ecosystem. Here, we provide both DEM and orthomosaic images for the years 1967 and 1984 for the Bale Mountains in Ethiopia, which comprise the largest afro-alpine ecosystem in Africa. We used 298 historical aerial photographs captured in 1967 and 1984 for generating DEMs and orthomosaics with Structure from Motion Multi View Stereo Photogrammetry along an elevation gradient from 977 to 4377 m above sea level (asl) at spatial resolutions of 0.84 m and 0.98 m for the years 1967 and 1984, respectively. Our datasets can be used by researchers and policymakers for (1) watershed management, as the area provides water for more than 30 million people; (2) landscape management; (3) detailed mapping and analysis of geological and archaeological features, as well as natural resources; (4) analyses of geomorphological processes; and (5) biodiversity research.