Author(s): Mai Taniguchi; Kazuho Aga; Kohji Michioku; Keiichi Kanda
Linked Author(s): Keiichi Kanda, Kohji Michioku
Keywords: Willow vegetated cannel; Numerical flood flow analysis; Drag force moment; River morphology; Field measurement
Abstract: In order to investigate how vegetated floodplain affects flow drag force on trees, a field survey and hydrodynamic analysis were performed in a vegetated river channel. A hydrodynamic analysis was conducted by a two-dimensional two-layer (2D2L) flow model that can analyze a wide range of water level and vegetated height. A field measurement was carried out in order to examine tree destructed behaviors during flood events, which was compared with the analytical solution of drag force. The observed locations of destructed trees were well correlated with the areas where a significant drag force moment was numerically estimated to occur. The model was additionally applied for discussing river and forest management strategies that could most efficiently promote flooding on the vegetated floodplain to destruct the trees. Taking tree growth rate into consideration, several scenarios for forest felling and floodplain excavation were assumed to evaluate the tree destruction probability under a flood event with a certain return period. It was found from the analysis that floodplain excavation and thinning and felling of trees could promote tree destruction due to flood flows.
Year: 2013