Freshwater Flocculation Dependence on Turbulence Properties in the Usumacinta River

AbstractFreshwater flocculation in the Usumacinta River delta during the high flow season was confirmed and supported by field data and the results from experiments conducted in a rotating annular flume and in a settling column device. Although the stream intensity and a bottom macroform generated and disturbed the 3D turbulence components in the cross section, the flow patterns followed the logarithmic law and the Nezu and Nakagawa models. The Rouse model can be applied to predict suspended sediment flux; however, flocculation led to diffusivity ratios less than 0.63 and effective settling velocities close to 1 mm/s that were consistent with the mass conservation equation. When comparing the suspended load patterns of several lowland rivers, flocculation stages are related to shear rate; furthermore, in contrast to saline environments, the representative aggregate size in freshwater systems is presumably higher than the Kolmogorov microscale.