Articles | Volume 15, issue 9
Research article
02 Sep 2015
Research article |  | 02 Sep 2015

Selective deposition response to aeolian–fluvial sediment supply in the desert braided channel of the upper Yellow River, China

H. Wang, X. Jia, Y. Li, and W. Peng

Abstract. Rivers flow across aeolian dunes and develop braided stream channels. Both aeolian and fluvial sediment supplies regulate sediment transport and deposition in such cross-dune braided rivers. Here we show a significant selective deposition in response to both aeolian and fluvial sediment supplies in the Ulan Buh desert braided channel. The Ulan Buh desert is the main coarse sediment source for this desert braided channel, and the mean percentage of the coarser (> 0.08 mm) grains on the aeolian dunes surface is 95.34 %. The lateral selective deposition process is developed by the interaction between the flows and the aeolian–fluvial sediment supplies, causing the coarser sediments (> 0.08 mm) from aeolian sand supply and bank erosion to accumulate in the channel centre and the finer fluvial sediments (< 0.08 mm) to be deposited on the bar and floodplain surfaces, forming a coarser-grained thalweg bed bounded by finer-grained floodplain surfaces. This lateral selective deposition reduces the downstream sediment transport and is a primary reason for the formation of an "above-ground" river in the braided reach of the upper Yellow River in response to aeolian and fluvial sediment supplies.

Short summary
Rivers flow through aeolian dunes and always adopt braided stream channels in response to aeolian and fluvial sediment supplies. Here our results indicate that these braided rivers are distinguished from coarser-grained thalweg beds and finer-grained bar or floodplain surfaces and develop a significant lateral selective deposition in bed sediment. The traditional downstream fining shows no significance in this braided channel, primarily due to aeolian sand supplies.
Final-revised paper