Variation in reach-scale thalweg-migration intensity in a braided reach of the lower Yellow River in 1986-2015

2017 ◽  
Vol 42 (13) ◽  
pp. 1952-1962 ◽  
Author(s):  
Jie Li ◽  
Junqiang Xia ◽  
Meirong Zhou ◽  
Shanshan Deng ◽  
Xiaolei Zhang
Keyword(s):  
Yellow River ◽  
Lower Yellow River ◽  
The Lower Yellow River ◽  
Migration Intensity ◽  
Braided Reach

scholarly journals Variations in Channel Centerline Migration Rate and Intensity of a Braided Reach in the Lower Yellow River

2021 ◽  
Vol 13 (9) ◽  
pp. 1680
Author(s):  
Junqiang Xia ◽  
Yingzhen Wang ◽  
Meirong Zhou ◽  
Shanshan Deng ◽  
Zhiwei Li ◽  
...  
Keyword(s):  
Arid Region ◽  
Migration Rate ◽  
Yellow River ◽  
Channel Migration ◽  
Lower Yellow River ◽  
Migration Rates ◽  
The Lower Yellow River ◽  
Migration Intensity ◽  
The Mean ◽  
Braided Reach

The Yellow River (YR) covers three climatic zones including arid region, semi-arid region and temperate monsoon region, with frequent appearance of flow intermittence in the Lower Yellow River (LYR) before 1999. Channel migration occurs frequently in braided rivers, which is a major focus of study in geomorphology and river dynamics. The braided reach in the LYR is featured by a complexly spatio-temporal variation in channel migration parameters owing to the varying condition of flow and sediment. It is crucial to investigate the migration characteristics of channel centerline for the sake of fully understanding channel evolution. A detailed calculation procedure is proposed to quantify migration rates and intensities of channel centerline at section- and reach-scales, using the measurements of remote sensing images and cross-sectional topography. Migration rates and intensities of channel centerline at section- and reach-scales from 1986 to 2016 were calculated, with the characteristics and key factors to control the migration intensity of channel centerline being identified quantitatively. Calculated results indicate that: (i) the mean probability of centerline migrating toward the left side was approximately equal to the probability of rightward migration from a long-term sequence; (ii) the mean reach-scale migration rate of channel centerline was reduced from 410 m/yr in 1986–1999 to 185 m/yr in 1999–2016, with a reduction of 55% owing to the Xiaolangdi Reservoir operation in 1999, and the mean reach-scale migration intensity of channel centerline was decreased from 0.28 to 0.16 m/(yr·m), with a reduction of 43%; (iii) the incoming flow-sediment regime was a dominant factor affecting the degree of channel migration, although the channel boundary conditions could influence the intensity of channel migration; and (iv) the reach-scale migration intensity of channel centerline can be written as a power function of the previous two-year average incoming sediment coefficient or fluvial erosion intensity, and the reach-scale migration intensities of channel centerline calculated using the proposed relations are generally in close agreement with the measurements over the period of 30 years.

scholarly journals Coupled modeling of bed evolution and bank deformation in the braided reach of the Lower Yellow River

2021 ◽  
Author(s):  
YingZhen WANG ◽  
JunQiang XIA ◽  
ShanShan DENG ◽  
MeiRong ZHOU ◽  
YiFei CHENG ◽  
...  
Keyword(s):  
Yellow River ◽  
Coupled Modeling ◽  
Lower Yellow River ◽  
The Lower Yellow River ◽  
Bed Evolution ◽  
Braided Reach

scholarly journals Evolution process of different abnormal river bends in the braided reach of the Lower Yellow River

2020 ◽  
Vol 32 (6) ◽  
pp. 1837-1847
Author(s):  
JIANG Qingrong ◽  
◽  
XIA Junqiang ◽  
ZHOU Meirong ◽  
WANG Yingzhen
Keyword(s):  
Yellow River ◽  
Evolution Process ◽  
Lower Yellow River ◽  
The Lower Yellow River ◽  
River Bends ◽  
Braided Reach

Channel geometry adjustments in response to hyperconcentrated floods in a braided reach of the Lower Yellow River

2018 ◽  
Vol 42 (3) ◽  
pp. 352-368 ◽  
Author(s):  
Jie Li ◽  
Junqiang Xia ◽  
Meirong Zhou ◽  
Shanshan Deng ◽  
Zenghui Wang
Keyword(s):  
Sediment Transport ◽  
Yellow River ◽  
Empirical Relation ◽  
Characteristic Parameter ◽  
Transport Rate ◽  
Channel Geometry ◽  
Lower Yellow River ◽  
The Lower Yellow River ◽  
Sediment Transport Rate ◽  
Braided Reach

Hyperconcentrated floods with more than 200–300 kg/m3 sediment concentrations often occur in the Lower Yellow River (LYR) during flood seasons, which leads to unique fluvial processes in the braided reach of the LYR. The investigation of channel geometry adjustments in response to hyperconcentrated floods can not only help to gain a better understanding of associated fluvial processes, but also is significant for making flood control strategies in the braided reach. In this study, pre- and post-flood bankfull channel dimensions in the braided reach were calculated based on the observed cross-sectional profiles in 15 years with the occurrence of hyperconcentrated flood events. Adjustments in channel geometry at section- and reach-scales were investigated, with several factors influencing adjustments in reach-scale channel geometry being analyzed. It indicates that the mean sediment transport rate was a key factor influencing the adjustment index, although pre-flood channel geometry and sediment deposition can also affect the index to some extent. An empirical relationship was developed between the characteristic parameter representing the pre- and post-flood channel geometries and mean sediment transport rate in hyperconcentrated floods. Eleven datasets were used to calibrate the parameters in the empirical relation, with the datasets in 1973, 1988, 1995, and 2002 verifying the relation. The calculated post-flood characteristic parameter of channel geometry using the empirical relation agreed well with observed data, and the proposed method can be used to predict the reach-scale adjustment of channel geometry during hyperconcentrated floods in alluvial rivers.

scholarly journals Changes in sediment budget and morphology in the floodplains of the braided reach of the lower Yellow River

2021 ◽  
Author(s):  
Yan Li ◽  
Jinliang Zhang ◽  
Yuchuan Bai ◽  
Zhe Huang ◽  
Jun Lu
Keyword(s):  
Yellow River ◽  
Land Use Changes ◽  
Land Development ◽  
Sediment Budget ◽  
Floodplain Management ◽  
Lower Yellow River ◽  
The Lower Yellow River ◽  
Regulation Scheme ◽  
Digital Elevation ◽  
Braided Reach

Floodplains provide valuable social and ecological environment functions, and understanding the rates and patterns of floodplain sedimentation/erosion is critical for floodplain management and rehabilitation. The sediment entering the lower Yellow River has been dramatically reduced, and the geomorphology has changed greatly during the operation of the Xiaolangdi (XLD) reservoir since 2000. Utilizing sediment resources is the key to managing the downstream river, and the floodplains not only play the roles of flood mitigation, detention and de-sanding but also provide land to support local residents and economic development; however, the floodplain currently faces competition between land development and protection. This research presents a detailed investigation of changes in the sediment budget and morphology of the braided reach between Huayuankou (HYK) and Gaocun (GC) during 2000-2017 using digital elevation models (DEMs) and the historical bathymetry of the braided reach. During the implementation of the water-sediment regulation scheme (WSRS), the long-term low-concentration flow released from the XLD reservoir leads to a fully scoured long channel, further improving the bank-full discharge and reducing the risk of floods on floodplains. However, the floodplains have gradually changed from sedimentation to erosion due to the continual construction of farm dykes and control works, land use changes and other forms of land disturbance, including water and soil conservation measures and climate change. The cumulative eroded volume was approximately 11.47×108 m3 along the HYK - GC reach between 2000 and 2017, of which 3.08×108 m3 originated from the floodplains, with an average annual erosion rate of 1.3 cm/yr. To develop the economy and guide floodplain construction, we propose a new method of environmental management to reconstruct the floodplain domain into different zones for immigration resettlement areas, agricultural areas and resource development and utilization areas, with the methods of river dredging and floodplain filling.

MODEL FOR LOSS ASSESSMENT DUE TO FLOOD IN THE LOWER YELLOW RIVER

2015 ◽  
Vol 14 (8) ◽  
pp. 1933-1939
Author(s):  
Xianqi Zhang ◽  
Weiwei Han ◽  
Xiaofei Peng ◽  
Cundong Xu
Keyword(s):  
Yellow River ◽  
Loss Assessment ◽  
Lower Yellow River ◽  
The Lower Yellow River
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