Drag in Vegetation Canopy: Considering Sheltering and Blockage Effects

Vegetation plays a crucial role in river hydrodynamic processes, and the accurate prediction of vegetation drag force is essential for effective river management and ecosystem protection. The interactions within the vegetation canopy must be quantified to understand their impact on drag force. This study delves into the canopy interaction mechanisms of rigid emergent aquatic vegetation, with a specific focus on blockage and sheltering effects. Through a series of flume experiments, we systematically explored various combinations of lateral and longitudinal spacing, including special single row and single column arrangements. Our experimental design includes various combinations of lateral and longitudinal spacing, as well as special single row and single column arrangements. This allowed us to provide a more precise understanding of how lateral and longitudinal spacing affect the blockage and sheltering effects. Furthermore, we introduced a unified reference velocity that combines two effects, based on which we have established a widely applicable drag model that can predict drag under various density conditions. Additionally, we propose a critical characteristic value for quantifying drag, shedding light on the ultimate performance of drag under different spacing arrangements. These findings offer a reliable framework for predicting drag in rigid emergent vegetation canopies, significantly advancing our comprehension of vegetation's influence on hydrodynamic processes. The established drag model serves as a practical tool for river management and ecosystem protection, providing valuable guidance for sustainable environmental practices.