Determination of controls on sediment transport in semi-alluvial boulder-bed streams

This study aims to identify sediment transport controls in semi-alluvial boulder-bed rivers. Tracer movement was collected over a two-year period using passive radio frequency transponders. Each tracer was associated with a class of constrainment, morphology and its relative proximity to a rock. This study deals with the data relating to reaches of three different rivers. No clear pattern was found, showing a high variability associated to hydraulic perturbation related to the boulders in the stream. No grain size correlation with the transport distance was found and it seems like the class of constrainment does not control the sediment transport as expected. Furthermore, the forecast of the incipient movement cannot rely on basics critical Shields stress as Shields or Lamb’s one