Flume experiments of sediment transport in unsteady flow

Adapted equipment of a test flume with semi-circular cross-section controls and measures flow and friction characteristics during the transient regime. A series of sediment transport measurements under unsteady flow conditions is performed for two types of non-cohesive material. Due to the inertia of the bed material, there's no agreement on form or time appearance between the unsteady friction velocity and the bedload transport. On the other hand an instantaneous relation between bedload transport and the friction velocity calculated with a steady state formula is revealed. The suspended material has obviously less inertia. Nevertheless suspension transport is also put proportional to the steady part of the friction velocity. A time shift, increasing with the unsteady character of the flow, appears between suspension transport and the steady part of the friction velocity. As a result, these experiments indicate the complex nature of unsteady sediment transport phenomena and initiate a fundamental understanding of these complex processes.