Sustainability, Vol. 12, Pages 1573: A Study of the Water and Sediment Transport Laws and Equilibrium Stability of Fluvial Facies in the Ningxia Section of the Yellow River under Variable Conditions (Sustainability)

Recently, construction of many large-scale water conservancy projects, as well as the vegetation protection and restoration projects in the upper reaches of the Yellow River, have led to serious changes in water inflow processes, sediment inflow processes, and scour and silting situation in the Ningxia section of the Yellow River (NSYR). This study explored the relationship between the sediment scouring and the silting law of the sediment-laden rivers and the equilibrium fluvial facies in the NSYR. The double cumulative curves of the annual silting amounts and annual incoming sediment amounts in the Qingtongxia–Shizuishan section were then established. It has been previously proven the fluvial facies coefficient increases year by year with the increase in the silting amounts in the watercourse, which lead to the evolution of the watercourse toward the wandering reach. The fluvial facies relationships of their cross-sections under an equilibrium state in the NSYR were established using a Yalin fluvial facies method. The Fr values under an equilibrium state and the actual state were analyzed. The results showed the Xiaheyan section was in an equilibrium state, and the Qingtongxia and Shizuishan cross-section were in a scouring state. This conclusion was confirmed by the actual measured results for numerous years.