Measuring, observing and pattern recognition of sediment transport in an armoured river using a sampler with attached underwater camera

In a small part of the Meuse, the only gravel bed river in the Netherlands, bed load transport cannot be measured from a measuring vessel because of the large flow velocities at flood discharges. Since 1994 these measurements were carried out from bridges by means of a truck with a winch. The first measurements were carried out with a Helley-Smith sampler and since 1997 the BTMA-2 sampler was used. The measurements of the bed load transport at the flood discharge of 2770 m³/s proved these measurements could be carried out for the entire range of discharges (Fig. 1).

On top of both samplers an underwater camera was attached by which pictures of the river bed and the inflowing bed load were taken and stored on a video tape. The combination of the measurements with pictures of the river bed give an explanation of the complex morphological behaviour of the Common Meuse at varying discharges due to the building of an armour layer. The latest measurements of the bed load transport (1998) show the timeshift between maximum discharge and maximum bed load transport as shown earlier in laboratory experiments (Klaassen, 1987).