scholarly journals Controls of channel morphology and sediment concentration on flow resistance in a large sand-bed river: A case study of the lower Yellow River

Geomorphology ◽  
2016 ◽  
Vol 264 ◽  
pp. 132-146 ◽  
Author(s):  
Yuanxu Ma ◽  
He Qing Huang
Keyword(s):  
Flow Resistance ◽  
Yellow River ◽  
Sediment Concentration ◽  
Channel Morphology ◽  
Lower Yellow River ◽  
The Lower Yellow River

Response of channel geometry to flow and sediment conditions in the lower Yellow River

2020 ◽  
Author(s):  
Huan Jing ◽  
Deyu Zhong ◽  
Hongwu Zhang
Keyword(s):  
Yellow River ◽  
Management Strategies ◽  
Sediment Concentration ◽  
Main Channel ◽  
Channel Stability ◽  
Cross Sectional ◽  
Channel Geometry ◽  
Lower Yellow River ◽  
The Lower Yellow River ◽  
Erosion Intensity

<p>The channel geometry in a fluvial river is significantly affected by the flow and sediment regimes, and the response behavior of channel dimensions usually varies widely to different management strategies from the upstream reservoir. Therefore, it is significantly crucial to investigate the variation of the channel geometry in response to changing flow and sediment conditions and quantify the influence of the latter in the sedimentation reduction and flood releasing in lower reaches downstream of the dam. In this study, three laboratory experiments on the physical model covering the typical braided reach HGK—JHT downstream of the Xiaolangdi Reservoir in the lower Yellow River are carried out, under the discharge of 2000 m<sup>3</sup>/s, 3000 m<sup>3</sup>/s, and 4000 m<sup>3</sup>/s respectively and with the corresponding constant suspended sediment concentration of 8.0 kg/m<sup>3</sup>. Results indicate that (i) spatially, the erosion and deposition in studied channel reach distributed alternately along the course which performs typical evolution properties of the braided river, corresponding to the total erosion amount of 2.27×10<sup>6 </sup>m<sup>3</sup>, 10.29×10<sup>6</sup> m<sup>3</sup>, and 7.98×10<sup>6</sup> m<sup>3</sup> for three magnitude of discharges; and (ii) four representative adjustment patterns are listed based on the observed cross-sectional geometry after each experiment, including the lateral widening pattern, vertical incision pattern, composite pattern and geometrical stable pattern where sectional geometry rarely changes during the period of experiment; and (iii) the quantity <em>ξ=B</em><sup>1/2</sup>/<em>H</em> where <em>B</em> and <em>H</em> is the width and depth of the main channel zone is selected as the typical indicator to determine the variation of the channel stability. It is discovered that <em>ξ </em>in the reaches upstream of section FJS have rather larger values, implying relatively wider and shallower sectional geometry and lower channel stability which is closely associated with the levee safety. And moreover, the quantity <em>ξ </em>generally has lower values, that is, higher channel stability with the increase of experiment discharge; Besides, through the method of nonlinear regression analysis, the empirical relations for HGK—JHT Reach are developed between the main channel dimensions and incoming flow erosion intensity <em>F</em>=(<em>Q</em><sup>2</sup>/<em>S</em>)/10<sup>6</sup> where <em>Q</em> is the discharge and <em>S</em> is the corresponding sediment concentration. In general, the calculated results are generally consistent with the measured values, as the riverbed degradation and the variation of sectional area increase exponentially with a stronger erosion intensity <em>F</em>.This paper may provide some practical basis for the study of channel evolution in sediment-laden rivers.</p>

scholarly journals Variational-Based Data Assimilation to Simulate Sediment Concentration in the Lower Yellow River, China

2016 ◽  
Vol 21 (5) ◽  
pp. 04016010 ◽  
Author(s):  
Hong Wei Fang ◽  
Rui Xun Lai ◽  
Bin Liang Lin ◽  
Xing Ya Xu ◽  
Fang Xiu Zhang ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Yellow River ◽  
Sediment Concentration ◽  
Lower Yellow River ◽  
The Lower Yellow River

scholarly journals Response of Erosion and Deposition of Channel Bed, Banks and Floodplains to Water and Sediment Changes in the Lower Yellow River, China

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 357 ◽  
Author(s):  
Xiaofei Liu ◽  
Changxing Shi ◽  
Yuanyuan Zhou ◽  
Zhenkui Gu ◽  
Huijuan Li
Keyword(s):  
Yellow River ◽  
Water Discharge ◽  
Sediment Concentration ◽  
Main Channel ◽  
River Channel ◽  
Lower Yellow River ◽  
Main Research ◽  
The Lower Yellow River ◽  
Water And Sediment ◽  
Geomorphic Units

River channel change can be very sensitive to environmental change and human activities and it has been one of the main research topics in fluvial geomorphology. In this study, repeated channel geometric measurements were used to investigate the channel adjustment to water and sediment changes of the lower Yellow River in China in the past few decades. With a high sediment concentration and large variations of water discharge, the lower Yellow River has a much active channel in its form and location, which has hindered previous research efforts to study long-term differentiated erosion/deposition of different geomorphic units in the channel. In this study, we divided each of four typical channel across-sections at hydrological stations in the lower Yellow River into different units according to the geomorphological features, and give a detailed investigation of erosion/deposition processes of these geomorphic units and the interactions between them besides the influence of incoming water and sediment conditions. The results show that with a significant decreasing trend of both the annual runoff and sediment load of the river and abrupt changes in 1985–1996, the overall siltation trend in the river channel before 1990 had been replaced by a slight erosion trend after 2006. In the earlier period, the siltation in the upstream wandering and transitional reaches mainly occurred on floodplains and that in the downstream straight reaches principally on main channel bed. In the later period, erosion occurred mainly on high and low bank slopes in the wandering reaches and on main channel bed in the transitional reaches. The erosion became weak in the wandering reaches after 2010, continued in the transitional reaches, and was still relatively minor in the straight reaches, reflecting the downstream hysteresis channel response to changes in water and sediment discharges down dams. Our results suggest that the seasonal erosion/deposition of a geomorphic unit of the river channel can be attributed to the changes in water and sediment discharges as well as to the interaction between geomorphic units. Siltation on the main channel bed could be attributed to erosion on the bank slopes in both the sections in the wandering and transitional reaches, and erosion of the main channel bed in flood seasons was negatively related with the mean water discharge at the two sections in the straight reaches. This result implies that fixing the bank slopes in the wandering and transitional reaches and raising the water discharge in the straight reach in flood seasons are favorable options for controlling the development of the two-level perching channel of the lower Yellow River.

scholarly journals Prediction of sediment concentration based on the MEEMD-ARIMA model in the lower Yellow River

2019 ◽  
Vol 11 (4) ◽  
pp. 1570-1579
Author(s):  
Xianqi Zhang ◽  
Fei Liu ◽  
Chao Song ◽  
Xiaoyan Wu
Keyword(s):  
Flood Control ◽  
Yellow River ◽  
Moving Average ◽  
Arima Model ◽  
Sediment Concentration ◽  
Lower Yellow River ◽  
Autoregressive Integrated Moving Average ◽  
The Lower Yellow River ◽  
Frequency Domains ◽  
Annual Sediment

Abstract There are many factors influencing the evolution of sediment concentration, and it is difficult to determine and extract, which brings great difficulties to the high-precision prediction of sediment concentration. Accurate prediction of annual sediment concentration in the lower Yellow River can provide a theoretical basis for flood control and disaster reduction and rational utilization of water and soil resources in the lower Yellow River. For the defects of pseudo-components in data decomposition of Complementary EEMD, the Modified EEMD (MEEMD) method proposed in this paper has the advantage of eliminating pseudo components of IMF and reducing non-stationarity of sediment bearing sequences. Then, combined with the Autoregressive Integrated Moving Average (ARIMA) model with strong approximation ability to the stationary sequence, the MEEMD-ARIMA model for predicting the annual sediment concentration in the lower Yellow River was constructed. Through fitting and predicting the annual sediment concentration in Gaocun Station, it is shown that the model not only considers the evolution of sediment concentration in various frequency domains, but also solves the problem that the ARIMA model requires sequence to be stable, the relative error of prediction is within ±6%, and the prediction accuracy is high, thus providing a new method for the prediction of sediment concentration.

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