Numerical modelling of turbidity currents in the Xiaolangdi reservoir, Yellow River, China

<p>Turbidity currents are a major way to transport sediment along reservoir, lake and sea beds. They are not fully understood yet due to the difficulty of accessibility. Theoretical criteria have been established for the conditions that generate accelerating turbidity currents, which can produce strong erosion of channel beds, transmit over long distances and thus have important significance for reservoir and sea bed morphology. However, the current theoretical criterion only utilizes local factors of hydraulic, morphology and grain size, which do not necessarily depend on the up- and down- stream boundary conditions. Here, we conducted field surveys on turbidity currents and bed morphology of the Xiaolangdi reservoir on the Yellow River, China. The survey results show clear evidence of accelerating turbidity currents. We identify two types of accelerating turbidity currents: one locates closely to the upstream plunging point where fluvial sediment-laden flow collapses to a stratified turbidity current, concentrating momentum and producing acceleration locally, and the other is located downstream and shows dependence on the enhancement of local slope and potentially on downstream boundary (flushing condition at flow outlets of the dam). So both ends of the boundaries may work together to produce long run-out turbidity currents that transmit through the entire reservoir.&#160; Although preliminary, our dataset indicates that the conditions for accelerating turbidity currents are not only controlled by local morphology and grain size, but also by both upstream and downstream conditions. A comprehensive understanding of the boundary conditions so as to determine conditions for the generation of accelerating turbidity currents will help enhance the sustainability of the dam and reservoir system.</p>

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Design and Application of an In Situ Test Device for Rheological Characteristic Measurements of Liquefied Submarine Sediments

Journal of Marine Science and Engineering ◽

10.3390/jmse9060639 ◽

2021 ◽

Vol 9 (6) ◽

pp. 639

Author(s):

Hong Zhang ◽

Xiaolei Liu ◽

Anduo Chen ◽

Weijia Li ◽

Yang Lu ◽

...

Keyword(s):

Yellow River ◽

Rheological Characteristic ◽

Yellow River Delta ◽

Turbidity Currents ◽

Rheological Characteristics ◽

Submarine Landslides ◽

Test Device ◽

Offshore Area ◽

In Situ Test

Liquefied submarine sediments can easily lead to submarine landslides and turbidity currents, and cause serious damage to offshore engineering facilities. Understanding the rheological characteristics of liquefied sediments is critical for improving our knowledge of the prevention of submarine geo-hazards and the evolution of submarine topography. In this study, an in situ test device was developed to measure the rheological properties of liquefied sediments. The test principle is the shear column theory. The device was tested in the subaqueous Yellow River delta, and the test results indicated that liquefied sediments can be regarded as “non-Newtonian fluids with shear thinning characteristics”. Furthermore, a laboratory rheological test was conducted as a contrast experiment to qualitatively verify the accuracy of the in situ test data. Through the comparison of experiments, it was proved that the use of the in situ device in this paper is suitable and reliable for the measurement of the rheological characteristics of liquefied submarine sediments. Considering the fact that liquefaction may occur in deeper water (>5 m), a work pattern for the device in the offshore area is given. This novel device provides a new way to test the undrained shear strength of liquefied sediments in submarine engineering.

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Effects of tributary inflow and sediment input on reservoir turbidity current formation and evolution

10.5194/egusphere-egu21-4656 ◽

2021 ◽

Author(s):

Yining Sun ◽

Ji Li ◽

Zhixian Cao ◽

Alistair G.L. Borthwick

Keyword(s):

Yellow River ◽

Sediment Concentration ◽

Turbidity Current ◽

Turbidity Currents ◽

Front Speed ◽

Sediment Input ◽

Formation And Evolution ◽

Maximum Utilization

<p>For reservoirs built on a hyper-concentrated river, tributary inflow and sediment input may affect the formation and evolution of reservoir turbidity current, and accordingly bed morphology. However, the understanding of tributary effects on reservoir turbidity currents has remained poor. Here a series of laboratory-scale reservoir turbidity currents are investigated using a coupled 2D double layer-averaged shallow water hydro-sediment-morphodynamic model. It is shown that the tributary location may lead to distinctive effects on reservoir turbidity current. Clear-water flow from the tributary may cause the stable plunge point to migrate upstream, and reduce its front speed. Sediment-laden inflow from the tributary may increase the discharge, sediment concentration, and front speed of the turbidity current, and also cause the plunge point to migrate downstream when the tributary is located upstream of the plunge point. In contrast, if the tributary is located downstream of the plunge point, sediment-laden flow from the tributary causes the stable plunge point to migrate upstream, and while the tributary effects on discharge, sediment concentration, and front speed of the turbidity current are minor. A case study is presented as of the Guxian Reservoir (under planning) on the middle Yellow River, China. The present finding highlights the significance of tributary inflow and sediment input in the formation and propagation of reservoir turbidity current and also riverbed deformation. Appropriate account of tributary effects is warranted for long-term maintenance of reservoir capacity and maximum utilization of the reservoir.</p>

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Study on Ecological Scheduling of the Xiaolangdi Reservoir Based on the Ecological Needs of Estuarine Fishes

MATEC Web of Conferences ◽

10.1051/matecconf/201824601045 ◽

2018 ◽

Vol 246 ◽

pp. 01045

Author(s):

Shimin Tian ◽

Yi Zhao ◽

Yuanjian Wang ◽

Enhui Jiang ◽

Shoubing Yu

Keyword(s):

Yellow River ◽

River Estuary ◽

The Yellow River ◽

Large Reservoir ◽

Lower Yellow River ◽

The Lower Yellow River ◽

Estuarine Fishes ◽

Water Demands ◽

Xiaolangdi Reservoir ◽

Water Amount

The total water amount into the Yellow River estuary is significantly reduced with the construction of a series of reservoirs in the Yellow River, which has a lot of adversely effects on the fishes and fishery resources in the estuary. This research analyzes the impacts of the reservoirs on the runoff and discharge in the Lower Yellow River and the estuary, and pays more attention to the influences of the reduction of water amount on the estuarine ecology and fishes. As a large reservoir nearest to the estuary in the Lower Yellow River, the operation of Xiaolangdi Reservoir plays an important role on the ecological restoration of the lower reaches of the Yellow River and the estuary. Two ecological operation schemes are proposed based on the ecological demands of the estuarine fishes and the actual operation of the Xiaolangdi Reservoir in recent years. One scheme is proposed only on the basis of the estuarine ecological water demands and another scheme takes consideration of ecological water demands and the actual status of the water resources in the Lower Yellow River synthetically. Finally, the feasibility of the two schemes are analyzed according to the actual situation of water storage of the reservoirs in the Yellow River in 2017.

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Variation on sandbar of tributary in Xiaolangdi Reservoir on Yellow River, China

MATEC Web of Conferences ◽

10.1051/matecconf/201824601019 ◽

2018 ◽

Vol 246 ◽

pp. 01019

Author(s):

Tao Li ◽

Jun-hua Zhang ◽

Guoming Gao ◽

Huaibao Ma

Keyword(s):

Flood Control ◽

Yellow River ◽

Deposition Process ◽

Utilization Efficiency ◽

Comprehensive Utilization ◽

Water And Sediment ◽

River Bed ◽

Main River ◽

Effective Use ◽

Xiaolangdi Reservoir

Sandbar development would stop the water and sediment exchange between main river and tributary and even influence the normal reservoir opeartion. From the surveyed data of reservoir built many years ago, it shows that when there is a bar in tributary mouth, the tributary volume below the bar will become nullification during the period of flood control or water and sediment regulation of reservoir. There are more tributaries in Xiaolangdi reservoir than the others that it occupies 41.3% of the total initial volume of tributary volume. Obviously, the effective use of tributary volume has been important influenced by comprehensive utilization efficiency of reservoir scheduling, such as flood control, sedimentation reduction and comprehensive utilization. Results of Xiaolangdi Reservoir mobile-bed physical model experiments show that tributary is equivalent to lateral extension of river bed, the tributary intrusion deposition process have strongly relations with the factors, such as original topography, river bed deposition shape and its regime, process with input discharge and input sediment, and method of reservoir regulation. The variation trends of main river and tributary terrain forecasted by model test are basically in accordance with field surveyed data. The results could be used for research, design, and forecasting of reservoirs in sediment-laden river.

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Environmental impact assessments of the Xiaolangdi Reservoir on the most hyperconcentrated laden river, Yellow River, China

Environmental Science and Pollution Research ◽

10.1007/s11356-016-7975-4 ◽

2016 ◽

Vol 24 (5) ◽

pp. 4337-4351 ◽

Cited By ~ 17

Author(s):

Dongxian Kong ◽

Chiyuan Miao ◽

Jingwen Wu ◽

Alistair G.L. Borthwick ◽

Qingyun Duan ◽

...

Keyword(s):

Environmental Impact ◽

Yellow River ◽

Environmental Impact Assessments ◽

Xiaolangdi Reservoir

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High Efficient Sediment-Transport Water Volume in High Sediment-Laden River

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.214.265 ◽

2011 ◽

Vol 214 ◽

pp. 265-270

Author(s):

Jun Yan ◽

Biao Liang ◽

Hui Cao ◽

Yu Hua Zhang

Keyword(s):

Sediment Transport ◽

Transport Process ◽

Field Data ◽

Yellow River ◽

Water Volume ◽

The Lower Yellow River ◽

Calculating Method ◽

High Efficient ◽

Xiaolangdi Reservoir ◽

High Sediment

Analyzed the sediment-transport process in high sediment-laden river, the new concept and calculating method for sediment-transport water volume are proposed. Based on field data of sediment and water volume in the Lower Yellow River from 1950 to 2000, the sediment-transport water volume and unit sediment-transport water volume in LYR are calculated. Meanwhile, relations between them and influencing factors are confirmed to calculate efficient sediment-transport water volume after construction of the Xiaolangdi reservoir.

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Monitoring the spatiotemporal dynamics of surface water body of the Xiaolangdi Reservoir using Landsat-5/7/8 imagery and Google Earth Engine

Open Geosciences ◽

10.1515/geo-2020-0305 ◽

2021 ◽

Vol 13 (1) ◽

pp. 1290-1302

Author(s):

Ruimeng Wang ◽

Li Pan ◽

Wenhui Niu ◽

Rumeng Li ◽

Xiaoyang Zhao ◽

...

Keyword(s):

Surface Water ◽

Water Body ◽

Vegetation Index ◽

Yellow River ◽

Google Earth ◽

Body Type ◽

Body Area ◽

Surface Water Body ◽

Google Earth Engine ◽

Xiaolangdi Reservoir

Abstract Xiaolangdi Reservoir is a key control project to control the water and sediment in the lower Yellow River, and a timely and accurate grasp of the reservoir’s water storage status is essential for the function of the reservoir. This study used all available Landsat images (789 scenes) and adopted the modified normalized difference water index, enhanced vegetation index, and normalized difference vegetation index to map the surface water from 1999 to 2019 in Google Earth Engine (GEE) cloud platform. The spatiotemporal characteristics of the surface water body area changes in the Xiaolangdi Reservoir in the past 21 years are analyzed from the water body type division, area change, type conversion, and the driving force of the Xiaolangdi water body area changes was analyzed. The results showed that (1) the overall accuracy of the water body extraction method was 98.86%, and the kappa coefficient was 0.96; (2) the maximum water body area of the Xiaolangdi Reservoir varies greatly between inter-annual and intra-annual, and seasonal water body and permanent water body have uneven spatiotemporal distribution; (3) in the conversion of water body types, the increased seasonal water body area of the Xiaolangdi Reservoir from 1999 to 2019 was mainly formed by the conversion of permanent water body, and the reduced permanent water body area was mainly caused by non-water conversion; and (4) the change of the water body area of the Xiaolangdi Reservoir has a weak negative correlation with natural factors such as precipitation and temperature, and population. It is positively correlated with seven indicators such as runoff and regional gross domestic product (GDP). The findings of the research will provide necessary data support for the management and planning of soil and water resources in the Xiaolangdi Reservoir.

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