Experimental study of plunging turbidity currents in reservoirs

Abstract

Laboratory experiments were conducted to investigate the hydraulic behaviour of plunging turbidity currents in reservoirs. One-dimensional turbidity currents driven by uniform non-cohesive sediment (silica flour) were generated in a 16.5m long, 0.3m wide and 0.75m high channel. Measurements of velocity profiles, suspended sediment concentration profiles and grain size distributions provided important insights into the spatial evolution of turbidity currents structure. The dimensional velocity profiles collapsed in a single curve confirming the similarity to a wall jet velocity profile. Downstream the plunge region, the spanwise evolution of the mean velocity profiles reveals that the point of maximum velocity increases gradually, approaching a constant value of 30% of the current thickness, which corresponds to a fully developed wall region. The study also shows the existence of a dimensional sediment concentration profile for each particle size.