Did streamflow or suspended sediment concentration changes reduce sediment load in the middle reaches of the Yellow River?

Sediment is a natural component of riverine environments and its presence in river systems is essential. However, in many ways and many places river systems and the landscape have been strongly affected by human activities which have destroyed naturally balanced sediment supply and sediment transport within catchments. As a consequence a number of severe environmental problems and failures have been identified, in particular the link between sediments and chemicals is crucial and has become a subject of major scientific interest. Sediment load and sediment concentration are therefore highly important variables that may play a key role in environment quality assessment and help to evaluate the extent of potential adverse impacts. This paper introduces a methodology to predict sediment loads and suspended sediment concentrations (SSC) in large European river basins. The methodology was developed within an MSc research study that was conducted in order to improve sediment modelling in the GREAT-ER point source pollution river modelling package. Currently GREAT-ER uses suspended sediment concentration of 15 mg/l for all rivers in Europe which is an obvious oversimplification. The basic principle of the methodology to predict sediment concentration is to estimate annual sediment load at the point of interest and the amount of water that transports it. The amount of transported material is then redistributed in that corresponding water volume (using the flow characteristic) which determines sediment concentrations. Across the continent, 44 river basins belonging to major European rivers were investigated. Suspended sediment concentration data were collected from various European basins in order to obtain observed sediment yields. These were then compared against the traditional empiric sediment yield estimators. Three good approaches for sediment yield prediction were introduced based on the comparison. The three approaches were applied to predict annual sediment yields which were consequently translated into suspended sediment concentrations. SSC were predicted at 47 locations widely distributed around Europe. The verification of the methodology was carried out using data from the Czech Republic. Observed SSC were compared against the predicted ones which validated the methodology for SSC prediction.

Download Full-text

Laboratory Study on the Relationships Between Suspended Sediment Concentration and Electrical Conductivity

Volume 7: Offshore Geotechnics; Petroleum Technology ◽

10.1115/omae2009-79211 ◽

2009 ◽

Cited By ~ 1

Author(s):

Qian Dai ◽

Hongxian Shan ◽

Yonggang Jia ◽

Xiangmei Meng ◽

Honglei Li ◽

...

Keyword(s):

Electrical Conductivity ◽

Suspended Sediment ◽

Suspended Sediment Concentration ◽

Yellow River ◽

Influencing Factor ◽

Yellow River Delta ◽

Sediment Concentration ◽

Conductivity Sensor ◽

Linear Relationships ◽

High Turbidity

In order to find a simple, continuous method to determine the suspended sediment concentration in a high turbidity region, experiments were conducted to look for relationships between suspended sediment concentration and electrical conductivity. Sediments were sampled from the Yellow River Delta and a conductivity sensor was used to measure the electrical conductivity of different sediment content seawater. The influencing factors such as temperature and salinity are also investigated. The results show that good linear relationships exist between suspended sediment concentration and electrical conductivity; salinity and temperature have some influence on electrical conductivity, and salinity is the most important influencing factor and temperature takes the second place. Basically, the general linear regression formulas between suspended sediment concentration and electrical conductivity can be drawn with variable salinity and temperature. The relationships suggest that it is feasible to measure suspended sediment concentration in situ using electrical conductivity sensors.

Download Full-text

Effect of Wave, Current, and Lutocline on Sediment Resuspension in Yellow River Delta-Front

Water ◽

10.3390/w12030845 ◽

2020 ◽

Vol 12 (3) ◽

pp. 845 ◽

Cited By ~ 1

Author(s):

Bowen Li ◽

Yonggang Jia ◽

J. Paul Liu ◽

Xiaolei Liu ◽

Zhenhao Wang

Keyword(s):

Suspended Sediment ◽

Yellow River ◽

Yellow River Delta ◽

Sediment Concentration ◽

River Delta ◽

Low Flow ◽

The Yellow River ◽

Delta Front ◽

The Yellow River Delta ◽

Hindered Settling

Historically, the Yellow River in China discharges > 1 × 109 ton/yr sediment to the sea, and has formed a large delta in the western Bohai Sea. Its river mouth is characterized by an extremely high suspended sediment concentration (SSC), up to 50 g/L. However, the hydrodynamic factors controlling the high suspended sediments in the Yellow River estuary are not well understood. Here, we conducted two hydrodynamic observations and SSC measurements in the winter and spring low-flow seasons of 2014–2015 and 2016–2017 under five sea conditions, including calm-rippled, smooth-wavelet, slight, moderate, and rough, in the Yellow River Delta-front during the observation period. Under calm-rippled conditions, the contribution of currents to the total resuspended sediment concentration (RSC) was 77.7%–100.0%. During the smooth-wavelet and slight periods, the currents’ contribution decreased as low as 30% and 3.0% of the total RSC, respectively. Under moderate and rough-sea conditions, waves accounted for at least 70% and 85% of the total RSC, respectively. The results indicate that 20 cm-thick lutoclines were created after a significant increase in the wave height to a peak value followed by a decrease. When the SSC is over 3 g/L and hydrodynamic conditions could not break the lutoclines, the flocculent settling of suspended sediment changes to hindered settling in the Yellow River Delta. Under hindered settling, the settling velocity decreases, and the resuspended sediments remains in the lutoclines and their lower water layers. This study reveals different controlling factors for the high SSC near a river-influenced delta, and helps us get a better understanding of a delta’s resuspension and settling mechanisms.

Download Full-text

Analysis of Runoff-Sediment Cointegration and Uncertainty Relations at Different Temporal Scales in the Middle Reaches of the Yellow River, China

Water ◽

10.3390/w12092589 ◽

2020 ◽

Vol 12 (9) ◽

pp. 2589

Author(s):

Xiujie Wang ◽

Dandan Li ◽

Ximin Yuan ◽

Xiling Qi ◽

Pengfei Zhang

Keyword(s):

Sediment Load ◽

Yellow River ◽

Hysteresis Loops ◽

Yellow River Basin ◽

Sediment Concentration ◽

The Yellow River ◽

Uncertainty Relations ◽

Rating Curves ◽

Runoff Sediment ◽

Cointegration Relationship

To understand the intricate runoff-sediment relationship in the middle Yellow River basin (MYRB), the Toudaoguai, Longmen, Tongguan and Huayuankou sites in the MYRB were selected to analyze the deterministic equilibrium and uncertainty relations of runoff-sediment based on 55-year hydrological data at multi-time scales. The Johansen test and wavelet neural network were used to verify the cointegration relationship among hydrological series. Runoff-sediment uncertain statistical relations and dynamics in the MYRB were also analyzed based on rating curves and hysteresis loops. The results showed that the logarithmic sequences of sediment load (SL), runoff and suspended sediment concentration (SSC) conformed to a linear cointegration relationship at the Toudaoguai station or in spring, winter or under small flow at other stations, but a nonlinear cointegration relationship was observed in other cases at other stations. Regarding runoff-sediment uncertain relationships, the rating curves, and hysteresis loops differed in stations (Toudaoguai and the other stations), as well as discharge (threshold: 1000 m3/s), season (ice-flood and rainy season) and saturation of flow at flood and monthly scales. At the annual scale, phased and unsynchronized characteristics of runoff and sediment load were evident with a decreasing trend. This study on the runoff-sediment relationship can rationally provide a theoretical basis for the management and development of the Yellow River and other similar rivers with sufficient sediment, especially for areas with serious soil erosion.

Download Full-text

Reconstructing the suspended sediment load of the Yellow River since 1470 CE using the Drought and Flood Index

Geomorphology ◽

10.1016/j.geomorph.2017.10.003 ◽

2017 ◽

Vol 299 ◽

pp. 131-141 ◽

Cited By ~ 2

Author(s):

Jiongxin Xu

Keyword(s):

Suspended Sediment ◽

Sediment Load ◽

Yellow River ◽

The Yellow River ◽

Suspended Sediment Load ◽

Drought And Flood ◽

Flood Index

Download Full-text

Dynamics of suspended sediment load in the Morava River (Serbia) in the period 1967-2007

Revista de Geomorfologie ◽

10.21094/rg.2016.076 ◽

2016 ◽

Vol 18 (1) ◽

pp. 47-58

Author(s):

Sanja MANOJLOVIĆ ◽

Predrag MANOJLOVIĆ ◽

Mrdjan DJOKIĆ

Keyword(s):

Suspended Sediment ◽

Suspended Sediment Concentration ◽

Sediment Load ◽

Water Discharge ◽

Sediment Concentration ◽

Suspended Sediment Load ◽

Test Results ◽

Pettitt Test ◽

Mk Test ◽

Morava River

The study is concerned with determination of the trend of water discharge, suspended sediment concentration and sediment load in the most downstream profile of the Velika Morava River in the period 1967-2007. The gradual trend test (Mann–Kendall test – MK test) and abrupt change test (Pettitt test) have been employed on annual, seasonal and monthly water discharge, suspended sediment concentration and suspended sediment load for the given time series. Both the Mann–Kendall and Pettitt tests indicate that water discharge showed no significant annual trend or abrupt shift. However, annual suspended sediment concentration and sediment load showed significant decreasing trends (α=0.001). The average decrease of suspended sediment load transport amounted to 3.15 t/km2/yr. The Pettitt test results showed that the change-point year was detected in 1982. The average specific sediment load amounted to 134.6 t/km2/yr before the transition year, and 36.5 t/km2/yr after the transition year, i.e., it was reduced by 73 %. In the intra-annual distribution, the MK test results indicate that the most pronounced decreasing trend (α=0.001) of the sediment load is during summer and winter. Strong seasonal and monthly variability in sediment load was found. Sediment was strongly transported during spring months, in the period of frequent flood events. Almost 50% of the annual sediment is transported during March, April and May. Analysis of the discharge and suspended sediment concentration relationship revealed the existence of hysteresis loop in the shape of figure eight. The results of this study confirm the complex and heterogeneous nature of sediment response in the Velika Morava River.

Download Full-text