A partitioned model for predicting the spatial development of flow in ecological vegetated rivers with submerged vegetation. (May 2023)

• Record Type: Journal Article
• Authors: Zhang, Jiao; Geng, Yingying; Wu, Zi; Wang, Wen; Miao, Mengmeng; Wang, Huilin; Li, Zhanbin; Guan, Muhong
• Is Part Of: Ecological indicators. Volume 149(2023)
• Publication Date: 2023-05
• Subjects: Submerged vegetation -- Four-panel analytical model -- Exponential decay theory -- Rectangular open channel -- Velocity evolution; Environmental monitoring -- Periodicals; Environmental management -- Periodicals; Environmental impact analysis -- Periodicals; Environmental risk assessment -- Periodicals; Sustainable development -- Periodicals; 333.71405
• DOI: 10.1016/j.ecolind.2023.110146
• Languages: English
• ISSNs: 1470-160X

Abstract

Highlights: Streamwise velocity evolution in submerged vegetated flow is predicted. New partitioned model is proposed and applied in the submerged vegetated flow. Flow structure and development features are illustrated in vegetated flow. Abstract: The evolution of the velocity caused by submerged vegetation in river courses with regular cross sections has been poorly investigated using analytical methods. Fully understanding the longitudinal profiles of the velocity is significant and essential to study the hydrodynamic processes taking place in wetland ecosystems, which is the most important indicator of energy transfer and material exchange in fluvial ecosystems. Based on the experimental data in the literature, the streamwise velocity gradually is found to decrease in the submerged vegetation and increase in the free surface layer. A four-panel analytical model derived from exponential decay theory was developed to predict the streamwise velocity occurring both upstream and within vegetation along the main flow direction in a rectangular open channel with a submerged vegetation patch. We aim at the development of velocity, which is averaged across the vegetation and free surface layers separately, and the length scales shown in the velocity evolution. The explicit calculation expression for each parameter in the analytical model was provided, and sensitivity analysis was conducted by changing the parameters to check how the predicted velocity changed. The change in the drag coefficient of vegetation ( C D ) and the velocity at the leading edge of the vegetation ( U 0 ) influenced the development of velocity. The former mainly enlarges the velocity difference between the vegetation and free surface layers after the leading edge as it increases, and the latter mainly diminishes the velocity difference before the leading edge as it increases. The error statistics is conducted and shows that the predicted and measured velocities are consistent within a relative error of 11%, indicating that the partitioned model is applicable in predicting longitudinal velocity in flows with submerged vegetation of various flexibility. The theoretical analysis of velocity development paves the way for the future studies on the flow turbulent structure and sediment transport in partially vegetated rivers.