The influence of different types of permeable bed (Flexible vegetation and inflexible rod bundle) in gravity currents

Abstract

In this study, experiments were performed in a laboratory tank to investigate the effect of a permeable bed (flexible or inflexible) on the movement of gravity currents. The vegetation in the bed of the laboratory tank was simulated initially with grass to create flexible vegetation and then with rod bundles to create inflexible vegetation with the same vegetation bed height (hv = 10 cm). The number of rod bundles was 6200 m2 and the density of the grass (number of shoots per square meter) was 3 shoots/cm2. The density of the vegetation bed, α, in both cases was the same and was calculated as being equal to 0.20 cm-1. The experiments were carried out to investigate the effect of different permeable beds on the movement of gravity currents. The experiments were carried out in a laboratory tank, in which a removable thick vertical partition separated the two fluids (clear water and well-mixed saltwater) at density differences of 2%, 4%, and 6%. After removal of the partition, the created gravity current was monitored by a high-definition digital video camera. The movement of the current was studied (distance covered, effect of differences in density, effect of vegetation height). The experimental results were compared with experimental data from previously published research on gravity currents without the presence of a permeable bed and gravity currents through a random array of rigid, emergent cylinders that represented a canopy of aquatic plants. © 2017 by Begell House, Inc.