Author(s): Michaela Woerndl; Bernhard Gems; Christian Weber; Markus Aufleger
Linked Author(s): Markus Aufleger, Bernhard Gems
Keywords: Flood protection; Bed-load deposition basin; Alpine torrent; Fluvial sediment transport; Hydraulic scale model
Abstract: Settlements in Austrian alpine valleys are often characterized by a lack of habitable space. Houses and infrastructure are likely to be exposed to gravitational natural hazards. To allow for satisfactory protection of existing communities and lifelines, engineering solutions specific to this limited space have to be developed. In many alpine mountain torrents fluvial sediment transport significantly influences the hydraulics of the discharged flow. This has to be taken into consideration for the design of related flood control works or other hydraulic structures. In this paper it is presented how, through the application of a hydraulic scale model test, a flood protection project on an Austrian mountain torrent was tested and optimized. A 150-years design flood event with immense sediment transport was simulated for different scenarios. The project area lies within two villages, which are situated on a densely populated alluvial fan. The tested preventative measures consisted of new and raised floodwalls, raised embankments and an overflow section for the controlled overtopping of an existing dam. The torrent’s 150-years design flood event is characterized by immense fluvial sediment transport for which the bed-load deposition basin cannot provide sufficient room. Downstream of the basin is a narrow channel section where the space is limited due to an overpassing bridge. Extensive amounts of bed-load are released from the deposition basin into this channel section, which therefore is likely to clog. The clogging of the bridge and its disastrous impact was successfully replicated in the model. In a series of tests for the hydraulic optimization of the channel geometry close to the bridge a solution was found with which this clogging was avoided. The concepts, results and conclusions of the model test are presented in this work. It is shown how scale models can be used to find solutions for complex hydraulic engineering problems, specifically for those related to intensive fluvial sediment transport.
Year: 2013