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Title
Japanese: 
English:Analysis of the Impacts of Non-Primary and Bifurcation Channel Depths to the River Flow in Mekong Delta through the use of a Global River Model 
Author
Japanese: HOKSONJose Angelo Arocena, RevelNilanka Menaka Tisho Kumar, 山崎大, 鼎信次郎.  
English: Hokson, Menaka Revel, Dai Yamazaki, Shinjiro Kanae.  
Language English 
Journal/Book name
Japanese: 
English: 
Volume, Number, Page        
Published date Dec. 2020 
Publisher
Japanese: 
English:AGU 
Conference name
Japanese: 
English:AGU Fall Meeting 2020 
Conference site
Japanese:USA 
English: 
Official URL https://agu.confex.com/agu/fm20/meetingapp.cgi/Paper/664341
 
Abstract River mega deltas are vulnerable to destructive flood risks due to their river flow characteristics. Despite this, it is still hard to model river flows in these regions. CaMa-Flood, a global hydrodynamic model overcame these limitations by using a bifurcation channel scheme that considers multiple downstream connectivities. Even with this scheme, uncertainties remain in modeling flows in non-primary channels, which are channels connected to the main stem of primary channels through bifurcation channels. In this study, the impacts of the bifurcation and non-primary channel depths to the river flow in Mekong Delta for CaMa-Flood are analyzed. Non-primary channels were treated differently from primary channels by imposing several channel depths for non-primary channels and bifurcation channels connected to them. There were seven simulations with depths from 0.05 m to 70.0 m. Small depth values (0.05 m to 0.25 m) bring worsening in the simulated flow values in non-primary channels. Large depth values (10.0 m to 70.0 m) bring improvements to simulated flow values in non-primary channel flow values in the delta as much as 25% for annual mean discharge and 46% for annual peak discharge. Moreover, there is an increase in the water received by non-primary channels based on annual mean discharge and peak flood depth. Overall, it was found that larger channel depths simulate flows in non-primary channels better. Uncertainties remain in the simulated flow. The next goal is to find more optimum river channel depths by starting from large depth values and finding a relationship between channel depths and other hydrological and geomorphological parameters that might be optimized to a global scale. Ultimately, the final goal is creating a bifurcation methodology that applies to global hydrodynamic models.

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