Performance of soil bioengineering constructions for slope stabilization in torrent catchment areas

Different types of successfully applied bio-technical slope constructions are being investigated at the Department of Soil Bioengineering and Landscape Construction (University of Natural Resources and Applied Life Sciences, Austria) in order to assess long-term performance of bio-technical stabilization methods in torrent catchment areas. Insight into future protection potential and reliability is expected and will be the basis for the development of maintenance and care programs. The studies concentrate on the composition and condition of the stands, on the development of the root systems, on geological and soil parameters and on the condition of the auxiliary material (timber, jute mesh and other fibres). First steps in detailed investigations were done with hedge brush layers constructed in the early 1950s in the catchment areas of the torrents Geroldsbach and Enterbach in the Tyrolean Central Alps. By means of outstanding torrent control conception, the problematic catchment areas were successfully stabilized. The risk of erosion could be reduced considerably. At the present moment, the soil bioengineering constructions are still stable at both sites but the stands dominated by Alnus sp. are of advanced age, the risk of breaking down is increasing. The potential of natural succession and self-regeneration is rather low. Risk of slope instability remains due to geological site conditions.