Abstract
Abstract. Floods including intensive bedload transport represent a severe hazard to the often densely populated alluvial fans of small Alpine watersheds. In order to minimize the risk of future inundation, an existing bedload deposition area on the fan upstream of the village Vorderberg in southern Austria is planned for reconstruction. The suggested concept for protection measures includes dividing the area into three similar sections of reduced slope. The three sections are to be separated by a block ramp. To test this concept and to optimize the sedimentation process, an analysis was performed by using both a physical scale model (1:30) and a numerical simulation tool (SETRAC). Four configurations for the section-outlet were tested based on three flood scenarios. The results support the general protection concept and suggest a minimum construction configuration, including a woody debris filter. Employing a physical scale model for analysing small watershed processes is rarely found in literature. This contribution represents an applied study and provides quantitative information on bedload deposition and outflow from a deposition area. We test a novel simulation tool for bedload transport on the steep slopes against the measurements in the laboratory and show that the combination of physical and numerical modelling is a valuable tool to evaluate the efficiency of planned measures for torrent hazard mitigation.
Highlights
On 29 August 2003 a flood event hit the village of Vorderberg/St
We present continuous measurements of the deposition process for different hydrologic scenarios, three-dimensional deposition pattern resulting from three constructive measures to enhance the deposition process, as well as a comparison with a novel numerical simulation tool to model bedload transport and deposition in steep channels
Physical scale models represent a useful tool to evaluate the efficiency of flood protection measures
Summary
On 29 August 2003 a flood event hit the village of Vorderberg/St. Stefan, Austria, causing severe damage to several houses on the fan of the creek “Vorderbergerbach” (Fig. 1). During the course of a detailed event documentation (Huebl et al, 2004), sediment budgeting resulted in a total volume of about 450 000 m3 of eroded sediment in the channel and adjacent to the channel. 250 000 m3 of sediment, including some 50 000 to 80 000 m3 of bedload, were delivered to the fan. No quantitative assessment of woody debris recruitment and transport to the fan is available. Due to limited channel capacity and woody debris blockages at bridges, the village Vorderberg was flooded; sediment was deposited outside of the channel and was only partially delivered to the receiving river Gail
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
