Bed sediment particle size characteristics and its sources implication in the desert reach of the Yellow River

A 1000-km desert reach of the Yellow River flows through an extensive aeolian desert region. In recent years, the river bed of this reach has shown an aggradational trend, leading to substantial social, economic, and other environmental problems. The desert reach of the Yellow River provides an opportunity for us to study the sediment particle size characteristics and its sources, transport, and sedimentation processes in a large desert river. To investigate this topic, 111 shallow sediment core samples from the desert reach and some typical surface sediment samples were also systematically collected from the main reach and potential source areas in the upper Yellow River basin for particle size analysis. The analysis of sediment cores in the desert reach indicated that a fine sediment layer had developed over a coarse sediment layer in the 1- to 4-m-thick bed deposits. Aeolian sand, the Ten tributaries, and coarse fraction from the riverbank provide material for the development of the coarse sediment layer in the sediment cores, while the relatively fine sediment (<0.08 mm) from the Loess Plateau and fine fraction from the riverbank provide material for the development of the fine sediment layer. Particle sizes and their downstream variation along the upper reach of the Yellow River also suggest that the siltation of the Yellow River's desert reach is mainly caused by local coarse sand particles larger than 0.08 mm, which are very different from the sediment (>0.05 mm) coming from the Loess Plateau. Our results provide a meaningful reference for the management of desert rivers around the world.