Relationship between suspended sediment load, channel geometry and land area increment in the Yellow River Delta

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.

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Sedimentation in the Yellow River delta, part I: flow and suspended sediment structure in the upper distributary and the estuary

Marine Geology ◽

10.1016/s0025-3227(98)00031-0 ◽

1998 ◽

Vol 149 (1-4) ◽

pp. 93-111 ◽

Cited By ~ 67

Author(s):

Guangxue Li ◽

Helong Wei ◽

Yeshen Han ◽

Yiji Chen

Keyword(s):

Suspended Sediment ◽

Yellow River ◽

Yellow River Delta ◽

River Delta ◽

The Yellow River ◽

The Yellow River Delta ◽

Sediment Structure

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A Tale of Two Deltas: Comparative Study on the Effects of Dam Regulation on Deltaic Hydrological Regime and Morphological Evolution

10.5194/egusphere-egu21-1441 ◽

2021 ◽

Author(s):

Weilun Gao ◽

Dongxue Li ◽

Mawusi Amenuvor ◽

Yao Tong ◽

Dongdong Shao ◽

...

Keyword(s):

Sediment Load ◽

Yellow River ◽

Morphological Evolution ◽

Hydrological Regime ◽

Yellow River Delta ◽

River Delta ◽

The Yellow River ◽

Quasi Equilibrium ◽

The Yellow River Delta ◽

The World

<p>Deltas are among the most populous areas and most productive ecosystems on Earth. Despite their critical importance for human society and coastal ecosystems, many of the world&#8217;s deltas are drowning due to substantial decrease in sediment supply, sea level rise, etc. Previous studies have demonstrated the effects of dam regulation on the hydrological regime and morphological evolution of river deltas. However, past attention was mostly paid to individual deltas or deltas at a global scale, while comparative studies on selected deltas are scarce in the literature. In this study, a comparative study on two wave-influenced deltas, namely, the Volta River Delta in Ghana and the Yellow River Delta in China, was conducted. The trend of change of the annual river discharge and sediment load of the two deltas before and after the construction of the major dams were analyzed, and the resultant effects on deltaic morphological evolution were also examined and compared between the two deltas. The results show that the average annual river discharge and sediment load and their inter-annual variation decreased significantly after the construction of major upstream dams for both deltas. However, presumably due to the differences in reservoir capacity and upstream location of the dams, the sediment load of the Volta River Delta decreased abruptly to <10% of the sediment load in the pre-dam period after the construction of the Akosombo Dam in 1964 and became stable afterwards, whereas the sediment load of the Yellow River Delta decreased substantially to ~10% of pre-dam level but in a more gradual stepwise manner since the 1950s. As a result, after the intense shoreline retreat in the 1960s, the delta area of the Volta River Delta appeared to adjust to the reduced yet stable sediment load and shift to a new quasi-equilibrium with minimal change (maximum 0.53%). On the contrary, the Yellow River Delta still kept prograding at the river mouth given the current sediment load. However, it is foreseeable that if the trend of sediment reduction persists, it may potentially turn net delta progradation to erosion and further into a new quasi-equilibrium like the Volta River Delta. Our study provides a new perspective for understanding the future evolution of the Yellow River Delta as well as other deltas around the world that share similar characteristics and forcing factors.</p>

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Study on Spatiotemporal Evolution of the Yellow River Delta Coastline from 1976 to 2020

Remote Sensing ◽

10.3390/rs13234789 ◽

2021 ◽

Vol 13 (23) ◽

pp. 4789

Author(s):

Chengming Li ◽

Lining Zhu ◽

Zhaoxin Dai ◽

Zheng Wu

Keyword(s):

Environmental Sustainability ◽

Yellow River ◽

Reduction Rate ◽

Yellow River Delta ◽

River Delta ◽

The Yellow River ◽

Land Area ◽

The Yellow River Delta ◽

Delta Coastline ◽

Coastline Evolution

The Yellow River Delta in China is the most active one for sea–land changes over all deltas worldwide, and its coastline evolution is critical to urban planning and environmental sustainability in coastal areas. Existing studies rarely used yearly temporal resolution, and lack more detailed and quantitative analysis of coastline evolution characteristics. This paper used visual interpretation to extract the coastline of the Yellow River Delta in year interval Landsat images for 45 years from 1976 to 2020, and analyzed the spatiotemporal characteristics of the coastline evolution through statistical methods such as calculating change values and change rate. The main results are as follows: (1) overall, the coastline of the Yellow River Delta presented a spatial pattern involving northern landward retreat and southern seaward expansion. Since 1990, the Yellow River Delta has entered a period of decline. In addition, the length of the artificial coastline increased by about 55 km; (2) in the Qingshuigou region, the land area and the coastline length increased first and then stabilized. The southeastern part of the Qingshuigou was in a state of erosion, while the northeastern part was expanding toward the sea along the north direction; (3) in the Diaokou region, the land area has been decreasing, but the reduction rate has gradually slowed down. The main conclusions are as follows: (1) through the research on the evolution model and mechanism of the coastline of the Yellow River Delta, it was found that human factors and natural factors were the two major driving factors that affect the evolution of the coastline; (2) a river branch appeared in the northern part of the Qingshuigou region in 2014 and became a major branch in 2020, which would affect the development of the coastal region of Chengdao. This study is important for better understanding the evolution pattern of the Yellow River Delta coastline and will help to provide guidance for coastline management and resource exploitation.

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