Journal Article

Insights for River Restoration: The Impacts of Vegetation Canopy Length and Canopy Discontinuity on Riverbed Evolution

Li, Ming, Liu, Chao, Li, Fujian, Shan, Yuqi, Guo, Yakun

2024

Overview

River restoration projects often involve vegetation planting to retain sediment and stabilize riverbanks. Laboratory experiments have explored the impact of rigid emergent vegetation canopies on bed morphology. Inside canopies, bed erosion is attributed to vegetation‐induced turbulent kinetic energy (TKE). Based on the in‐canopy local TKE and the criteria for sediment movement, a method is established and validated for predicting the length of the bed erosion region. In the bare channel, bed erosion is related to the ratio of canopy length to flow adjustment distance, L/LI, and exhibits two trends. At L/LI < 1, the maximum depth, ds(bare), and length, Ls(bare), of the bed erosion region increase with increasing canopy length. At L/LI ≥ 1, ds(bare) and Ls(bare) are not influenced by the canopy length and remain constant. In vegetated regions with the same length and plant density, discontinuous canopies (streamwise interval s ≥ canopy width D) yield weaker bed erosion than continuous canopies. The mutual influence between two canopies must be considered if the canopy interval satisfies s < 3D. These results provide insights for designing vegetation canopies for river restoration projects. Key Points The impact of canopy length on bed morphology inside and outside the canopy is clarified A method for predicting the length of the bed erosion region inside canopies is established Discontinuous canopies produce weaker bed erosion than continuous canopies for the same vegetated region length and plant density

• Publisher: John Wiley & Sons, Inc,Wiley
• Subject: bed morphology / Canopies / Canopy / Discontinuity / discontinuous canopy / Emergent aquatic plants / Emergent vegetation / Environmental restoration / evolution / Kinetic energy / Laboratory experimentation / Laboratory experiments / Plant cover / plant density / Planting density / Restoration / River banks / River beds / River restoration / Riverbanks / Riverbeds / Rivers / Sediment / Sediment movement / sediments / stream channels / Turbulent kinetic energy / Vegetation / vegetation canopy / water