Research Theme

Turbulence and the Vegetation

We develop mechanistic turbulence models for vegetated flows that link roughness-induced flow restructuring to transport, mixing, and ecosystem function— from microscale turbulence physics to field-scale performance.

Vegetated Flows Eddy Diffusivity Reactive Transport

Why vegetation changes turbulence

Vegetation acts as boundary roughness with structure: it extracts momentum, reshapes turbulence, and reorganizes mixing pathways. These changes alter not only mean velocity profiles, but also how sediments, nutrients, and contaminants are transported and removed.

A key challenge is predicting how microscale turbulence modifications induced by vegetation translate into bulk flow structure and field-scale removal efficiency.

Our work develops analytical and numerical tools that connect these scales within a single, physically interpretable framework.

A framework for vegetated flow structure and transport

🌿 Asymmetric eddy diffusivity

Developed an asymmetric eddy diffusivity model capturing directional mixing differences introduced by canopy drag and wake production.

📐 Universal velocity distribution

Derived a universal velocity distribution equation using asymptotic analysis, linking canopy properties and roughness to mean profiles and shear stresses.

🧪 Reactive transport in wetlands

Applied numerical reactive transport modeling to quantify contaminant uptake by vegetation, connecting turbulence-driven exposure to removal efficiency.

From microscale physics to field-scale performance

Vegetation-induced turbulence modifies residence times, mixing pathways, and contact frequencies, providing a mechanistic explanation for observed differences in contaminant and nutrient removal.

The result is a scalable, physics-based link between flow structure, turbulent mixing, and field-scale removal efficiency, validated against empirical data.

What this framework enables

Predictive modeling of vegetated flow profiles and shear stresses
Mechanistic estimates of mixing and transport in canopy flows
Physics-based design of floating treatment wetlands
Cross-scale linkage from canopy turbulence to ecosystem-scale performance

Representative Publications

Li, S., & Katul, G. Contaminant removal efficiency of floating treatment wetlands. Environmental Research Letters, 15(10), 1040b7.
Li, S., Katul, G., & Huai, W. Mean velocity and shear stress distribution in floating treatment wetlands: An analytical study. Water Resources Research.
Tang, Z., Wang, W. J., Yuan, S., Li, S., & Xin, P. A turbulence model for velocity distribution in open-channel flows through mangrove trees. Water Resources Research, 61(8), e2024WR039599.