Scour and silting evolution and its influencing factors in Inner Mongolian Reach of the Yellow River

Abstract

Rivers with fluvial equilibrium are characterized by bed deformation adjustment. The erosion-deposition area in cross-section reflects this characteristic, which is a base of researching the river scour and deposition evolution by time series analysis. With an erosion-deposition area indicator method proposed in this paper, the time series of erosion-deposition area quantity at Bygl and Shhk stations were obtained with the series duration of 31 years from 1976 to 2006. After analysis of its trend and mutation, three different tendencies about the evolution were observed in general from the quasi-equilibrium phase through a rapid shrinkage to the final new quasi-equilibrium. It is also found that the trend of erosion-deposition area series will change once a big flood occurred in some of the tributaries, and its ever greater influence is due to the decrease of deluge with the completion of upstream reservoirs. Almost all the turning points were coincident with the time when hyper-concentrated sediment flood occurred in some tributaries. With the time series of clear mutations since the late 1990s, the Inner Mongolian Reach has been in a new equilibrium phase. This can be concluded in two aspects. 1. The absence of big floods and sediment transportation from tributaries result in the river shrinkage, and to regain the channel flow-carrying capacity in Inner Mongolian Reach a large flood is needed both of high peak discharge and of lengthy interval to destroy the new equilibrium. 2. The proposed method of erosion-deposition area indicator is of great help to channel scour-deposition evolution analysis because it can demonstrate real time deformation of cross section in quantity.The Inner Mongolian Reach is located in the upstream of the lower Yellow River with 10 tributaries of seasonal rivers originating in the Hobq Desert. In recent decades, the deposition rate along this reach has increased with rapid shrinkage of its main channel and a remarkable decrease of its flow-carrying capacity under the influence of the changing climate, reservoir regulation and incoming sediment from its 10 tributaries; the unstableness of river regime, severe bank collapse and the deposition of tributary entrance make it a grim situa-

Changes and influencing factors of the sediment load in the Xiliugou basin of the upper Yellow River, China

“…Rainstorms can give rise to hyperconcentrated flows easily in the region, and the flows often destroy railways, village and factories downstream Du et al, 2014). Moreover, flash floods in the ten tributaries have carried high sediment loads into the Yellow River, leading to heavy sedimentation in the Inner-Mongolia reach of the upper Yellow River (Liu et al, 2009;Qin et al, 2011;Xu, 2013;Du et al, 2014). To date, some researchers have examined the characteristics of runoff and sediment load in this region.…”

Lateral erosion/accretion area and shrinkage rate of the Linhe reach braided channel of the Yellow River between 1977 and 2014

“…Yao et al (2011Yao et al ( , 2012) also estimated erosion area change along the river banks in the Ningxia and Inner Mongolian reaches of the Yellow River based on satellite images from different years, concluding that annual mean erosion area decreased between 1958 and 2008. Additional research has been focused on thaw flood discharge (Yang, 1992), river course changes (Wu et al, 2006), channel pattern changes (Wang, 2008), the responses of channel cross-sections to flood processes , spatio-temporal variations in sediment filling capacity and sedimentation rate (Wang et al, 2012a), channel hydraulic geometric changes (Ran et al, 2012), and the factors influencing channel evolution (e.g., Fan et al, 2010;Qin et al, 2011;Li et al, 2012;Shi et al, 2013;Wang et al, 2014) in the Ningxia and Inner Mongolian reaches of the Yellow River.…”

Calculation method for sediment load in flood and non-flood seasons in the Inner Mongolia reach of the Yellow River

“…Some of them focused on the Inner Mongolia reach, a typical alluvial river reach of the upper Yellow River Shen et al, 2007;Ran et al, 2009;Wu et al, 2010;Qin et al, 2011;Ta et al, 2015). For example, Zhang et al (2008) established a sediment load equation based on the empirical sediment transport equation of "more input, more output" for the Inner Mongolia reach of the upper Yellow River.…”