A Scenario of Area Expansion of Stable Vegetation in a Gravel-Bed River Based on the Upper Tama River Case

Vegetation influence is not only important for the channel management, but also for natural habitats. Clearly, the expansion of in-stream vegetation found on the gravel bed depend on site factors, such as bed material, groundwater level and geology. Above other things, fine sediments play a important role. During floods, the deposit of fine sediments is affected by the numbers and types of vegetation, alterations of the volume and timing of flows, and changes in the amount and type of sediment through which the river with the gravel bed flows.The result of this research shows significant correlation in hydraulics between in-stream vegetation and the deposit of the fine sediment, and suggests the scenario of vegetation expansion in alluvial rivers.