Traditional bed shear stress‐based models (e.g., Rouse model) derived from the classic parabolic profile of eddy viscosity in open‐channel flows fail to accurately predict suspended sediment concentration (SSC) in flows with aquatic vegetation. We developed a two‐layer, turbulence‐based model to predict SSC profiles in emergent vegetated flows. Turbulence generated from vegetation, bed, and coherent structures caused by stem‐bed‐flow interaction are considered into the near‐bed turbulent kinetic energy (TKE) to calculate the effective bed shear velocity, ubeff*. The model, validated by experimental data, further showed that the thickness height of the near‐bed layer (effective bottom boundary layer), Hb, varies with flow velocity and canopy density. Two additional models are provided to estimate Hb and ubeff*. The model is expected to provide critical information to future studies on sediment transport, landscape evolution, and water quality management in vegetated streams, wetlands, and estuaries.

No abstract

Dissolved Oxygen (DO) is an important indicator for water quality in natural water environments (Kannel et al., 2007;Rudolf et al., 2002;Sanchez et al., 2006). It shows the amount of oxygen available to living aquatic organisms and thus has significant impacts on aquatic ecosystems (Kramer, 1987). DO fluxes at the air-water and sediment-water interfaces (AWI and SWI) govern the DO level in water. For example, in water quality management, surface aeration systems can be installed to enhance the surface gas transfer rate to keep the aquatic system well-aerated and prevent excessive algal blooms. This approach has been widely applied to lakes and rivers with high biological oxygen demand (BOD) by environmental engineers to maintain sufficient water quality to support a functional aquatic ecosystem. On the other hand, DO flux transferring from water to the sediment bed is controlled by the mass transfer and the biochemical uptake in the hyporheic zone, where surface water and shallow ground water mix and exchange nutrients (Boano et al., 2014;Harvey & Gooseff, 2015;Krause et al., 2017). The transfer process controls the biochemical composition of both surface water and ground water systems, which closely depends on the hydrodynamics conditions (S. Grant & Marusic, 2011;M. Heller et al., 2003; Figure 1).

No abstract

No abstract