Channel change at Toudaoguai Station and its responses to the operation of upstream reservoirs in the upper Yellow River

Abstract

The application of dams built upstream will change the input conditions, including water and sediment, of downstream fluvial system, and destroy previous dynamic quasi-equilibrium reached by channel streamflow, so indispensable adjustments are necessary for downstream channel to adapt to the new water and sediment supply, leading the fluvial system to restore its previous equilibrium or reach a new equilibrium. Using about 50-year-long hydrological, sedimentary and cross-sectional data, temporal response processes of Toudaoguai cross-section located in the upper Yellow River to the operation of reservoirs built upstream are analyzed. The results show that the Toudaoguai cross-section change was influenced strongly by upstream reservoir operation and downstream channel bed armoring thereafter occurred gradually and extended to the reach below Sanhuhekou gauging station. Besides, median diameter of suspended sediment load experienced a three-stage change that is characterized by an increase at first, then a decrease and an increase again finally, which reflects the process of channel bed armoring that began at Qingtongxia reservoir and then gradually developed downstream to the reach below Sanhuhekou cross-section. Since the joint operation strategy of Longyangxia, Liujiaxia and Qingtongxia reservoirs was introduced in 1986, the three-stage change trend has become less evident than that in the time period between 1969 and 1986 when only Qingtongxia and Liujiaxia reservoirs were put into operation alone. In addition, since 1987, the extent of lateral migration and thalweg elevation change at Toudaoguai cross-section has reduced dramatically, cross-sectional profile and location tended to be stable, which is beneficial to the normal living for local people.

Suspended sediment dynamics at different time scales in the Loushui River, south-central China

“…Cumulative anomaly method could also be used to identify the changing tendency of discrete sequential variables, such as sequential runoff and suspended sediment concentration (Ran et al, 2010;Wang et al, 2012a,b). It is a statistical method to visually identify the change tendency of discrete data and is extensively used in meteorology (Ran et al, 2010).…”

“…It is a statistical method to visually identify the change tendency of discrete data and is extensively used in meteorology (Ran et al, 2010). For a discrete series x i , the Cumulative anomaly (X t ) for data point x t can be expressed as…”

Responses of Water Level in China’s Largest Freshwater Lake to the Meteorological Drought Index (SPEI) in the Past Five Decades

“…The accumulative anomaly is commonly used to identify the changing tendency of meteorological and hydrological data, such as sequential precipitation, evaporation, and runoff [54]. In this study, the accumulative anomaly method is used for analyzing the seasonal variation trend of lake level.…”

Spatial and temporal variations of channel lateral migration rates in the Inner Mongolian reach of the upper Yellow River

“…Furthermore, valley confinement has played a critical role in controlling the evolution of the braided Platte River (Fotherby 2009). However, human activities, such as construction of artificial levees and dams, operation of reservoirs and barrages, and building of bank protection structures on river banks, have played increasingly more important roles in channel evolution by modifying natural geomorphologic dynamics of river systems at least in the past decades (e.g., Petts 1979Petts , 1984Church 1995;Brandt 2000;Ran et al 2010;Wang and Li 2011;Hossain et al 2013). In such alluvial rivers, the channels change frequently from reach to reach as a result of continuous erosion-accretion processes (Kummu et al 2008).…”

“…Recent studies have also paid attention to channel morphological changes by analyzing responses of channel cross-sections to flood processes and by investigating channel hydraulic geometry characteristics (Ran et al 2012). Moreover, natural and anthropogenic impacts on the channel changes have also been broadly discussed (e.g., Hou et al 2007;Shen et al 2007;Ran et al 2010;Wang et al 2012). In contrast, little work has been done regarding the channel migration rate for the Inner Mongolian reach.…”