Mechanisms of solute transport and dispersion in open channels with surface storage zones

Abstract

Surface storage zones are lateral recirculation areas, which play a significant role on many physical and biogeochemical processes in rivers. They have lower velocities and shear stresses, favoring the biodiversity of fish and vegetation, with longer residence times that also contribute to the uptake of nutrients and exchanges with the hyporheic zone1. In many cases they can determine the fate of contaminants throughout the watershed, storing and depositing contaminant-rich particles that can be formed in complex fluvial system as depicted in Fig. 1. In this investigation we perform PIV and 3D numerical simulations of the flow in a simple square geometry, using a hybrid URANS/LES turbulence model2,3 to provide new insights on the mechanisms of dispersion and transport of contaminants, and analyze the statistics of the mass exchange and residence times in the cavity.