aalto1 untyped-item.component.html
Flow resistance of floodplain vegetation mixtures for modelling river flows
Loading...
Access rights
openAccess
publishedVersion
URL
Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
This publication is imported from Aalto University research portal.
View publication in the Research portal (opens in new window)
View/Open full text file from the Research portal (opens in new window)
View publication in the Research portal (opens in new window)
View/Open full text file from the Research portal (opens in new window)
Unless otherwise stated, all rights belong to the author. You may download, display and print this publication for Your own personal use. Commercial use is prohibited.
Authors
Box, Walter
Järvelä, Juha
Västilä, Kaisa
Date
Department
Major/Subject
Mcode
Degree programme
Language
en
Pages
11
Series
Journal of Hydrology, Volume 601
Abstract
River flows are greatly influenced by floodplain vegetation with implications on hydrological and hydraulic conditions from cross-sectional to river reach scales. Flow models need to reliably reflect changes in the riverine environment, such as vegetation growth associated with altered flow regimes, increased sediment loads and eutrophication. Leaf area index (LAI) based approaches are increasingly used as tools to predict the flow resistance caused by natural vegetation. However, current LAI-based modelling involves uncertainty at low and high vegetation densities and flow velocities due to a lack of research and validation at the outer ranges. The aim of this paper is to investigate the flow resistance for a mixture of flexible floodplain vegetation consisting of woody plants and understory grasses of low to high densities (LAI = 1–5) over a wide range of mean flow velocities (0.05–1.2 m/s) at low relative submergences of 1–2. A novel flume setup was designed by using high-accuracy pressure sensors to measure flow resistance and force sensors to measure plant drag forces. Flow resistance decreased by 35–90% when the submergence H/hv increased from 1 to 2, which is a highly relevant range for floodplain flows. The results provided new evidence that LAI-based modelling of vegetative friction factors can be reliably extended from low to high LAI values for non-submerged vegetation. However, adjustments to existing LAI-based approaches are required for water stages higher than the vegetation height. Furthermore, the friction by the understory grasses cannot be neglected as often assumed in literature especially for cases of low plant densities and low relative submergences.
Description
Funding Information: We gratefully acknowledge the help of laboratory technician Antti Louhio in the flume setup and trainee Marco Maio for the help in the data collection. The research was funded by Maa- ja vesitekniikan tuki ry (No 36537 and 33271), Maj and Tor Nessling Foundation (No 201800045) and Academy of Finland (No 330217). Publisher Copyright: © 2021 The Author(s)
Other note
Citation
Box, W, Järvelä, J & Västilä, K 2021, 'Flow resistance of floodplain vegetation mixtures for modelling river flows', Journal of Hydrology, vol. 601, 126593. https://doi.org/10.1016/j.jhydrol.2021.126593