Preprints
https://doi.org/10.5194/esurf-2022-52
https://doi.org/10.5194/esurf-2022-52
 
20 Sep 2022
20 Sep 2022
Status: this preprint is currently under review for the journal ESurf.

Method to evaluate large wood behavior in terms of convection equation associated with sediment erosion and deposition

Daisuke Harada and Shinji Egashira Daisuke Harada and Shinji Egashira
  • International Centre for Water Hazard and Risk Management (ICHARM), Public Works Research Institute (PWRI), 1-6, Minamihara, Tsukuba, Ibaraki, 305-8516, Japan

Abstract. This paper proposes a method for describing large wood behavior in terms of the convection equation and the storage equation, which is associated with active sediment erosion and deposition. Recent flood hazards are characterized by numerous amounts of sediment and large wood supplied from upstream mountainous areas, which often exacerbate flood disasters in downstream areas. Previous studies proposed methods to simulate large wood behavior by tracking the motion of individual wood pieces in the flood flow using the Lagrangian method. This study aims to propose a method to simulate the behavior of large amounts of large wood in the flow field with active sediment transportation by employing the convection equation and the storage equation with sediment erosion and deposition to simulate the behavior of numerous numbers of large wood pieces. The proposed method is applied to simulate the flood flow with numerous amounts of sediment and large wood in the Akatani river flood disaster, 2017, where the production and transport processes of sediment and large wood from the basin during heavy rainfall events are employed as upstream boundary conditions for the flood flow analysis. The 2-D flood flow computations indicate that the flood flow can be significantly affected by the large wood deposition at the bridge in terms of water level, velocity distribution, and sediment deposition. The comparison between the field and simulation results addressing large wood deposition in the field demonstrates that the simulation method proposed in this study can reproduce large wood behavior successfully. Overall, since the proposed method makes it possible to simulate the behavior of a numerous number of large wood, it can be applied to the management of hazards, such as the Akatani River.

Daisuke Harada and Shinji Egashira

Status: open (until 05 Nov 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Daisuke Harada and Shinji Egashira

Daisuke Harada and Shinji Egashira

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Short summary
This paper proposes a method for describing large wood behavior in terms of the convection equation and the storage equation, which is associated with active sediment erosion and deposition. Compared to the existing Lagrangian method, the proposed method can easily simulate the behavior of Large wood in the flow field with active sediment transport. The method is applied to the flood disaster in the Akatani river 2017, and the 2-D flood flow computations are succesfully performed.