Abstract:

The accumulation of silt in some sections of the Yellow River from Ningxia to Inner Mongolia is serious. It is of great significance to clarify the sorting and deposition law of near-source coarse-grained sediment and far-source fine-grained sediment for the control of accumulated silt in Ningxia-Inner Mongolia section of Yellow River. In this study， based on the 120 sediment samples obtained by drilling hole in the river， the variation characteristics of coarse-grained sediment content along the river with d>0.05 mm， d>0.08 mm and d>0.1 mm were analyzed through particle size distribution and mineral and element composition of coarse and fine sediment. And the contribution of near-source coarse sediment and far-source fine sediment sorting deposition to river sediment deposition was quantitatively evaluated. The results show that the main deposition of the river channel in the Ningxia-Inner Mongolia section of the Yellow River is the coarse sediment （d>0.08 mm） from the near-source desert and its underlying Pisha sandstone area， while the fine sediment （d<0.05 mm） from the upstream loess area is mainly deposited in the river beach， contributing less than 30% to the deposition of the river channel. Therefore， the coarse-grained sediment entering the Yellow River along the desert near Yellow River and underlying Pisha sandstone induced by the process of wind and water erosion should be the focus of river deposition and 'suspended river' control in the Ningxia-Inner Mongolia section of the Yellow River.

Key words: selective deposition, coarse sediment, fine sediment, Ningxia-Inner Mongolia reach, Yellow River