scholarly journals Sediment and morphological changes along Yangtze River’s 500 km between Datong and Xuliujing before and after Three Gorges Dam commissioning

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Qiancheng Xie ◽  
James Yang ◽  
T. Staffan Lundström
Keyword(s):  
Morphological Changes ◽  
General Pattern ◽  
Three Gorges Dam ◽  
Appreciable Amount ◽  
Three Gorges ◽  
The Three Gorges ◽  
Seasonal Flow ◽  
Pool Level ◽  
Before And After ◽  
River Reach

AbstractThe impoundment of the Three Gorges Dam on the Yangtze River begins in 2003 and a full pool level is first attained in 2010. This process leads to reciprocal adjustments in flow discharge, sediment transport and morphology downstream of the dam. Based on 26-year recorded hydrologic data 1990–2015 and surveyed bathymetries 1998, 2010 and 2015, this study elucidates, before and after the commissioning of the dam, the alterations along the 500-km reach of the river. Two-dimensional numerical simulations are performed to predict future morphological changes by 2025. The analyses demonstrate that the impoundment modulates the seasonal flow discharges and traps an appreciable amount of sediment, resulting in enhanced erosion potential and coarsening of sediment. On a multi-year basis, the maximum discharge varies by a factor of 1.3 and the corresponding suspended load concentration and transport rate differ by a factor of 3.0 and 3.8, respectively. Combinations of surveyed and simulated bathymetries reveal its morphological responses to the changes. A general pattern of erosion is observed along the reach. In its upper 120 km, the process slows down towards 2025. In the middle 200 km, the erosion shifts, following the gradual impounding, to slight deposition, which then shifts back to erosion around September 2018. In the final 180 km, erosion continues without any sign of de-escalation, which is presumedly ascribed to tidal actions. The reach has not yet achieved a hydro-morphological equilibrium; the riverbed down-cutting is supposed to continue for a while. The combination of the field and numerical investigations provides, with the elapse of time, insight into the morpho-dynamics in the 500 km river reach.

scholarly journals Water quality response to hydropeaking regulation of the Three Gorges Dam and Gezhouba Dam, China

2022 ◽  
Author(s):  
Meili Feng ◽  
Yue Zhu ◽  
Jianfeng Ren ◽  
Shuyang Xu
Keyword(s):  
Water Quality ◽  
Flood Control ◽  
Three Gorges Dam ◽  
High Temporal Resolution ◽  
Three Gorges ◽  
Quality Indices ◽  
Water Quality Indices ◽  
The Three Gorges ◽  
River Reach ◽  
The Three Gorges Dam

Hydropeaking as the most prominent feature of flow alterations resulting from hydropower plants has received attention worldwide. Ramifications of hydropower on the downstream river systems mainly focus on hydrological regimes or long-term water quality changes. Exceptional knowledge is expected on the sub-daily changes of water qualities in the downstream river reach that is affected by the hydropeaking. In this study, we investigate the dynamics of hydropeaking and thermopeaking at the outlet of the Three Gorges Dam TGD using a high temporal resolution dataset, and inspect its association with water chemistry indices. Hourly measurements are analysed for the downstream station Yunchi , and compared with the upstream station Nanjinguan. The results show that along with water temperature, water quality indices such as dissolved oxygen, total Phosphorus, total nitrogen, PH, and electricity conductivity all show evident ‘peaking’ phenomenon in a short time. These divergent variations, however, are not valid for non-hydropeaking affected indicators including turbidity, permanganate index, and ammonia nitrogen. These hydropeaking-induced perturbations are mitigated by the flood control operation from July to September. This study demonstrates that water quality indices are sensitive to hydropeaking and thermopeaking with respect to the magnitude of change and the seasonal component during a year. The results provide additional evidence for the environmental impacts of hydropower regulation on the receiving river reach, and bridge the gap between hydropeaking studies and thermopeaking, and study water qualities variations that were seldom connected from the same temporal perspective in river research.

Regulation of Laijiapu Waterway in Jingjiang Reach

2014 ◽  
Vol 501-504 ◽  
pp. 2001-2006
Author(s):  
Ya Liu ◽  
Li Zheng ◽  
Cheng Tao Huang ◽  
Zhao Biao Huang ◽  
Lin Liu
Keyword(s):  
Yangtze River ◽  
Three Gorges Reservoir ◽  
Three Gorges ◽  
The Yangtze River ◽  
Point Bar ◽  
The Three Gorges Reservoir ◽  
The Three Gorges ◽  
Before And After ◽  
The Stability ◽  
Channel Bar

After impoundment of the Three Gorges Reservoir, Jingjiang reach, in the middle of the Yangtze River, has gradually shown a series of atypical fluvial features, adversely affecting the maintenance of waterways. Citing the Laijiapu Waterway, a meandering segment in the lower Jingjiang for example, this paper compared the fluvial features of the channel before and after the impoundment, summed up its navigation-obstructing features, and proposed guarding the point bar on the convex bank and channel bar in the widening section as a key to maintaining the stability of the navigation channels.

scholarly journals New evidence of Yangtze delta recession after closing of the Three Gorges Dam

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
X. X. Luo ◽  
S. L. Yang ◽  
R. S. Wang ◽  
C. Y. Zhang ◽  
P. Li
Keyword(s):  
Three Gorges Dam ◽  
Three Gorges ◽  
Yangtze Delta ◽  
The Three Gorges ◽  
New Evidence ◽  
The Three Gorges Dam
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