Sand Bars Developed in Bifurcated Points Cause Channels Migration or Abandonment: A Case from Ganjiang Delta, China

Sand bars are very common and important objects in river research. Previous studies have focused on location, characteristics, origin and effecting of point bar and channel bar; less have depicted bars happened in bifurcated... [ view full abstract ]

Sand bars are very common and important objects in river research. Previous studies have focused on location, characteristics, origin and effecting of point bar and channel bar; less have depicted bars happened in bifurcated mouth, which is exactly important to channel evolution and migration. In this study, we investigate 3 branching point bars (BPBs) in Ganjiang River, China, and describe their characteristics by analyzing of shapes, deposit profile, grain size and microfacies. We also compared distributions of 12 BPBs from upstream to downstream. The study show that BPBs are very common in river. Three apparent parts can identified in a BPB, which formed progradation configuration. BPBs tend to connect with bank and cause branch channel abandoned; or connect with merging point bars to separate the whole channel or force the river to migration. The study show a mechanism that river shape controlled distribution of sand bars, which however can grow and in turn affect the shape of river. The idea would be useful to understand self-adaption of river patterns.