Author(s): Yuji Toda; Tetsuro Tsujimoto; Hideki Maeda
Linked Author(s): Yuji Toda
Keywords: Riparian vegetation; Sand bed river; Vegetation growth model; Interspecific competition
Abstract: In the present study, a numerical simulation model was presented to describe the effects of growth and interspecific competition of riparian vegetation on the cross-sectional bed topography of sand bed river. The numerical simulation model consists of the flood stage module and the ordinary water stage module. The sediment transport and the resulting morphological change were calculated by the flood stage module. The lateral distribution of flow velocity was calculated by shallow water equation, in which the effect of vegetation on flood flow was taken into account via the flow retardation due to the drag of vegetation. The destruction of riparian vegetation communities was estimated by the flood stage module, in which the vegetation communities were assumed to be destroyed by the flood flow for the case that the local scour depth around vegetation stand becomes deeper than the root depth and for the case that the vegetation community is buried by the sediment deposition. The growth of riparian vegetation was estimated by the ordinary water stage module, which includes the interspecific competition between grass type vegetation and tree type vegetation. The results of the numerical simulation show that the grass type vegetation can survive at the area where the bed material sand is active during flood. The growth of the grass type vegetation enhances the deposition of fine sediment, which provides the stable habitat for the tree type vegetation.
Year: 2010