| Abstract: | Braided river is considered as the main river pattern developed on alluvial fans. But this is not true in Northwest China. Analysis and correlations of the characteristics of more than 10 rivers show that straight river is the main river pattern and braided river only develops on middle segment of the river in this district. The main factor to shape this river pattern on alluvial fans is the standing incision due to changes in precipitation and sedimentary condition caused by climate change since Holocene. Because of the tectonic movement and boundary condition from gravel to loess-like sediment. some rivers have fan-head trenching and others have fan-toe trenching with the U-shaped cross section. |
