Sediment sources in semi-arid subtropical environments cannot sufficiently be documented by conventional methods of remote sensing. Spatial resolution of satellite sensors as well as of conventional aerial photography does not correspond to the scale of geomorphodynamic processes. With a specially designed hot air blimp as a sensor platform, large scale aerial photographs can be obtained specifically aimed at the scientific demands (geometric and temporal resolution, normal colour or infrared small format film). The pictures are subsequently being transferred into digital format by electronic scanners in order to enable further processing by digital image processing systems.In a semi-arid region of the Ebro Basin, key processes of desertification are being investigated. Areas affected by sheet wash, rill erosion and stone pavements as well as patterns of vegetation distribution are differentiated using imagery acquired by this new method. The combination of these information levels provides insight into interactions of geomorphodynamics and vegetation succession on abandoned fields. Reduced infiltration capacity due to crusts leads to increased run-off and sheet erosion followed by the formation of rills and gullies which are the most important sources of suspended sediment.