Renaat De Sutter

Simulation of sediment transport during flood events: laboratory work and field experiments

Abstract This paper aims at initiating a fundamental understanding of the suspended load transport of river sediment in unsteady flow. Laboratory erosion tests as well as artificial flood experiments are used to evaluate the influence of the transient regime on the transport efficiency of the flow. The erosion experiments reveal that the transport capacity is augmented when the unsteadiness of the flow increases. However, the influence of the transient regime is counteracted by the cohesive properties of the river bed. Field experiments with artificial floods released from a reservoir into a small canal confirm these findings and show a relationship between the friction velocity and the suspended load transport. An appropriate parameter β is proposed to evaluate the impact of the transient regime on the transport of suspended sediment.

Use of artificial flood events to demonstrate the invalidity of simple mixing models

Abstract The whole of a basin responds to a precipitate on event. The resulting flood wave introduces a complex pattern of interrelated processes which occur in the vegetation, soil, bedrock, human facilities, channel and in the different parts of the basin. The main advantage of field experiments is that it becomes possible to exclude several governing factors or sources and to control others by the experimental design. In a small brook near Trier (Germany), artificial flood events are created. In-channel transport processes of sediment are investigated without taking into account the interference of soil erosion and runoff. It is demonstrated that kinematic waves-describing the translation of flow with limited hydraulic dispersion or diffusion-also occur in small basins. The kinematic waves-travelling only a few hundred meters-have a large impact on the relationship between the hydrograph and dissolved or particle-bound substances. Consequently, classifications and simple mixing models between those components are impeded.