Three-dimensional numerical modelling of floods in river corridor with complex vegetation quantified using airborne LiDAR imagery

Excessive flood flow over the historic diversion weir in the vegetated Asahi River in Okayama Prefecture, Japan, was recently recorded for the first time after its renovation work. Fluvial researchers analysed the diversion discharge for flood mitigation measures through laboratory studies and conve...

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Bibliographic Details
Published in:Journal of hydraulic research 2023-01, Vol.61 (1), p.88-108
Main Authors: Yoshida, Keisuke, Kajikawa, Yuki, Nishiyama, Satoshi, Islam, MD. Touhidul, Adachi, Shin, Sakai, Koichi
Format: Article
Language:eng ; fre
Subjects:
3-D vegetation model
Airborne remote sensing
Bathymetry
Discharge
Distribution
diversion flow
Flood flow
Floods
Flow distribution
Flow resistance
Land cover
Land use
Lidar
Mitigation
Numerical models
River beds
river flooding
Riverbeds
Rivers
STIV
Three dimensional models
topo-bathymetric LiDAR
Vegetation
Velocimetry
Vertical distribution
Vertical flow
Vertical mixing
Water levels
Weirs
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Summary:Excessive flood flow over the historic diversion weir in the vegetated Asahi River in Okayama Prefecture, Japan, was recently recorded for the first time after its renovation work. Fluvial researchers analysed the diversion discharge for flood mitigation measures through laboratory studies and conventional two-dimensional (2-D) depth-averaged simulations. The existing model was insufficient for simulation of certain phenomena such as flow resistance caused by vegetation branches and leaves and vertical flow distribution around the river corridor. Therefore, we developed a three-dimensional (3-D) vegetation resistance porous model by estimating topography, land cover, and vegetation distribution from airborne light detection and ranging (LiDAR) topo-bathymetry (ALB) data. Results show that the water level and flow regime were more reproducible than by referenced 2-D calculations when compared to space-time image velocimetry (STIV) data and field measurements. The diversion discharge designed using the proposed model is feasible with the current riverbed and vegetation conditions.
ISSN:0022-1686
1814-2079
DOI:10.1080/00221686.2022.2106596