Slope development reconstruction at two sites in the Bohemian Forest Mountains

Abstract

Although the Bohemian Forest is generally considered to be geomorphologically a rather stable region, there are localities which bear proof of a surprisingly high intensity of recent and even present day processes. A multidisciplinary method-ology based on the analysis of slope systems was used for researching the present and past dynamics of two hillslopes. Using the results of direct dilatometric monitoring (the slow creep of rock blocks reached a maximum of 1 mm year-1), GPS field mapping, sedimentology, geodetic measurements and DEM analyses, several common rules have been observed for the behaviour of two model localities and a likely polycyclic development established, with recurrence of mass-wasting cycles related to material supply thresholds. Radiometric dating of debris flow activity showed that the cycles span approximately 4000 years. In this area of rather stable bedrock conditions, at least two factors that decrease slope stability need to act together to activate slope processes: i.e. a favourable structural predisposition (dip of major joint or bedding planes) and an increase in relief through either glaciation or river incision. © 2010 John Wiley & Sons, Ltd.