Messung und Berechnung des Geschiebetransportes in Wildbachunterläufen am Beispiel der Urslau

The knowledge of bedload transport in downstream sections of mountain torrents is important for the understanding of the process, the design and building of structural measures and the analyses and assessment of floods with sediment transport. In recent years the request of the energetic use of downstream sections of mountain torrents in form of small hydro power plants has increased. As the potential risk in residential areas caused by mountain torrents is often high and hydro power plants influence, by the hydraulic-engineering and operating, the transport of water and sediments, the information of the spatial and temporal variability of sediment transport is essential. On the one hand basic information is important for torrent control to design and realise measures and as well to give evidence of the impacts of hydro power plants on discharge and sediment transport. On the other hand it is an essential issue for designers and operators of hydro power plants to get bedload transport data, which facilitate an improvement of the construction (e.g. bottom outlet for reservoir flushing, type of weir) and the operational mode (e.g. frequency of reservoir flushing, maintenance of residual flow reaches). The aims of the project are to develop an applicable method for downstream sections of mountain torrents to assess bedload transport, the measurement and analyses of bedload transport of the Urslau torrent in Salzburg over a period of four years, a review of existing approaches to calculate bedload transport using measured data and to work out possibilities to calibrate and adjust bedload transport formulas. A general suggestion to determine bedload transport of downstream sections of mountain torrents should be given.