抄録
The morphology of confluence points along mountanious streams is affected by geomorphological characteristics of tributaries, such as catchment size and channel slope. These characteristics also influence the way in which sediment is transported through channels and the volume of sediment supplied to confluence points. This is demonstrated at the Oyabu creek in the Kyushu mountain range, based on 2-years of field observations. The results were as follows.
(1) At the Oyabu creek, sediment yielded from tributaries accumulated at the confluence points of relatively small steep tributaries, and was transported to the lower reach of confluence points in the case of large gentle tributaries.
(2) Changes in sediment volume depended on the preceding volume of sediment in storage, irrespective of tributaries characteristics.
(3) Volumes of sediment yielded from tributaries increased with increasing catchment size.
