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REPPWAND-OSELITZENBACH LANDSLIDE (Carinthia, Austrian Alps)
1. Description of the site
 The area at the north slopes of the so called “Carnic Alps“ in the southern part of the Austrian county of Carinthia is affected by numerous mass movements.
Thus, the Naßfeld-area, dewatered by a torrent called Oselitzenbach, consists of the carbonian sedimentary beds containing clayey schists, sandstones, marls and limestones.
The Reppwand-Oselitzenbach sagging zone consists of interlayers of competent and incompetent rocks, which are highly deformed and disturbed by long-term sagging and gliding processes.
The movements (measurements since 1988) are very inhomogeneous, reaching from some cm/y up to some areas with deformations of more than 1 m/y.
2. Hazard analysis
Since 1988 geomorphological, geophysical, geodetic and volumetric analyses of the landslide features have been done. By the aid of these data, the input parameters for the run-out model will be generated.
In order to evaluate the propagation and the accumulation, the computer codes PFC2D or PFC3D , from Itasca © can be used. These codes allow calculating possible debris cones and the size of the propagation. So it is possible to estimate the area and the parameters of
the run-out behaviour. For these mechanisms the behaviour of the pore water pressure and the water level in the rock mass have to be considered.
3. Elements at risk
Since the deviation of the torrent near the toe of the sagging zone has been done, the movements could be reduced to 3 cm/y. The risk doesn’t exist in the slope itself but especially in the downstream valley section. In the years 1983 and 1987, after heavy rainfalls, the toe of the mass movements was eroded with deposition of 300.000 m³ and 50.000 m³, respectively.
Nevertheless, the even by the reduced movements the downstream villages of Tröpolach and Watschig in the main valley could be affected. Further the collapse of the slope could endanger the main road, the “Naßfeld – Bundesstraße”, which is a very important connection to another valley, the “Gailtal“.
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