modelling, capacity model, non-capacity model Measured and modelled transport paths of artificial tracer stones at a large gravel bed river

摘要

Within the scope of a large restoration project at the Austrian Danube, an ambitious sediment transport monitoring program using advanced measurement equipment was performed over four years. Besides bed load transport measurements conducted with a basket sampler and contact- free motion detection using an ultrasonic device, 40 artificial tracer stones of three different sizes.(b- axis = 27. 5 mm, 40 mm and 70 mm) were produced; coded radio acoustic transmitters were inserted into each tracer. The positions of the stones were detected weekly over a whole year, including a 15- year flood event. Mean transport velocity for the mean diameter of the bed material (27. 5 mm) was found at 10m per day and incipient motion was detected at lower discharges than predicted by commonly used uniform bedload transport formulae. The particle paths were found to be mostly bankline-parallel, even though the stones passed a 30 degree river bend. In addition, the transport paths were simulated using a 3D numerical model which showed comparable results.