GEOMORPHOLOGICAL DATING OF SCARPS USING LANDFORM EVOLUTION MODELS

Erosion has a significant influence on geomorphometric properties of scarps. Our aim is to relate the present-day shape of fault scarps and terrace risers to their ages. After a fast gravitational degradation the scarp slope decreases to the angle of repose. This decrease in the maximum scarp slope angle is associated with an increasing rounding of the profile edges. It is assumed that the stage of degradation as well as the rounding of the edges reflect the time span since scarp formation ceased. A model is presented to simulate such a temporal development of scarp degradation by erosion. The erosive action depends on the local slope and is described in terms of a diffusion equation. Since the diffusivity considers the effects of soil erosion, surface runoff and detachability of particles, a linearly increasing approach in downslope direction is suggested here. Such a linear approach describes the effect of erosion in a more realistic way in comparison to the usual choice of a constant diffusivity. The first results show a better match between simulation and actual data for profiles of the Upper Rhine Graben. For dating scarps it is inevitably necessary to calibrate the model which is a matter of current research.