The catchment of the ?Schöttlbach?- stream has become a very active and therefore dangerous mountain torrent catchment. The flood event of the year 2011 has turned the catchment into a highly erosive area with huge loads of sediment transported by the stream.This thesis tries to give an overview of the past areas of erosion, using aerial photographs which cover the whole catchment. The first aerial photographs to do so date back to the year of 1965, the latest ones from the year 2010, one year before the flood event of 2011.There is a long gap between the dates of the photographs. According to this fact and the small-scale patterned characteristics of the catchment area, the produced ortho-images were analysed visually and the areas of erosion were mapped on screen with a geographic information system (GIS). 8 classes of areas have been defined, as well as one class of uncertain areas. Those classes are either areas of erosion or are likely to be the origin of erosive processes.The mapped areas have been compared to a slope map and a geological map of the area. Erosion areas of the past and current erosion can be detected with aerial photographs and information about past events could be visualized, as long as there is proper photographic material available.