scholarly journals Seasonal changes of sediment fluxes in the Yangtze River: roles of precipitation change, human conservation measures in sub-basins, and large dams

2021 ◽  
Author(s):  
Shitian Xu ◽  
Yuanfang Chai ◽  
Yao Yue ◽  
Xia Yan ◽  
Xiaofeng Zhang
Keyword(s):  
Yangtze River ◽  
Flood Control ◽  
Precipitation Change ◽  
Sediment Flux ◽  
The Yangtze River ◽  
Sediment Yields ◽  
Sediment Fluxes ◽  
Conservation Measures ◽  
Dry Seasons ◽  
Sediment Reduction

Abstract Seasonal sediment flux change is a key issue in riverbed evolution and flood control. This paper analyzed variations in sediment fluxes of the Yangtze River in dry and flood seasons during 1961–2014 and the impacts of precipitation change and human interference. Sediment fluxes in both dry and flood seasons decreased by 6.8–74.6 and 14.6–38.7%, respectively, based on daily sediment observations at six mainstream stations. However, precipitation increased sediment yields in both dry and flood seasons by 0.72–4.22 t/km2 (3.5–17.8%) and 4.95–73.32 t/km2 (1.9–25.5%), respectively, based on the reconstructed sediment series without anthropogenic interference. Therefore, sediment reduction due to human conservation measures and dam construction was up to 0.07–20.74 t/km2 (0.9–64.6%) in dry seasons and 27.47–85.35 t/km2 (6.5–23.7%) in flood seasons during 1980–2002, and further reduced 3.61–41.31 t/km2 (46.0–102.9%) in dry seasons and 175.63–471.52 t/km2 (59.6–126.2%) in flood seasons after the Three Gorges Reservoir (TGR) became operational in 2003. Contributions of human activities in six subregions to the reduction of the seaward sediment fluxes were calculated. Thereinto, the TGR only took up 3.2 and 23.9% in dry and flood seasons, respectively, which is below expectation.

Seasonal variation in water and sediment fluxes of the Yangtze River under precipitation change and human interference

2021 ◽  
Author(s):  
Yao Yue ◽  
Yuanfang Chai ◽  
Shitian Xu ◽  
Xiaofeng Zhang
Keyword(s):  
Yangtze River ◽  
Sediment Load ◽  
Water Discharge ◽  
Water Flux ◽  
Precipitation Change ◽  
The Yangtze River ◽  
Human Interference ◽  
Sediment Fluxes ◽  
Water And Sediment ◽  
Sediment Reduction

<p>Seasonal change of water and sediment fluxes is an important issue in flood/drought control and ecosystem protection. Based on trend analysis in dry and flood seasons during 1960–2014 at six major gauging stations on the Yangtze River, the largest river in China, significant homogenization of intra-year water discharge was found, while sharp decrease of sediment load in both seasons was tested. By reconstructing water and sediment series without the human interference, contributions of precipitation change, large dam constructions on the mainstream, and other human activities in each of the sub-basins of the Yangtze River were separated and quantified. It shows that precipitation change attributed for 9.5–23.6% to discharge homogenization in the middle and lower reaches of the Yangtze River, and increased sediment yield by 1.9–25.5% in both dry and flood seasons. Being the largest hydraulic project in the world, the Three Gorges Dam only explains 17.5–27.2% of the downstream homogenization in water flux, and 3.2–23.9% of sediment reduction in both seasons. Relatively small but massive human interference in the sub-basins was recognized as the primary factor, contributing over 60% to discharge homogenization and over 70% to seasonal sediment reduction, most notably in the Hanjiang sub-basin for water flux and in the Jianglingjiang sub-basin for sediment load.</p>

scholarly journals A Spatiotemporal Statistical Method of Ship Domain in the Inland Waters Driven by Trajectory Data

2021 ◽  
Vol 9 (4) ◽  
pp. 410
Author(s):  
Fan Zhang ◽  
Xin Peng ◽  
Liang Huang ◽  
Man Zhu ◽  
Yuanqiao Wen ◽  
...  
Keyword(s):  
Statistical Method ◽  
Yangtze River ◽  
Domain Size ◽  
Inland Waters ◽  
The Yangtze River ◽  
Trajectory Data ◽  
Different Types ◽  
Dry Seasons ◽  
Ship Collision ◽  
Shape And Size

In this study, a method for dynamically establishing ship domain in inland waters is proposed to help make decisions about ship collision avoidance. The surrounding waters of the target ship are divided to grids and then calculating the grid densities of ships in each moment to determine the shape and size of ship domain of different types of ships. At last, based on the spatiotemporal statistical method, the characteristics of ship domains of different types of ship in different navigational environments were analyzed. The proposed method is applied to establish ship domains of different types of ship in Wuhan section of the Yangtze River in January, February, July, and August in 2014. The results show that the size of ship domain increases as the ship size increases in each month. The domain size is significantly influenced by the water level, and the ship domain size in dry seasons is larger than in the wet seasons of inland waters.

scholarly journals Numerical Simulation Study of Booming Effect in Fast Currents of Inland River

2018 ◽  
Vol 38 ◽  
pp. 03048
Author(s):  
Rongchang Chen ◽  
Chen Liu ◽  
Xiaofeng Luo ◽  
Wei Shen
Keyword(s):  
Numerical Simulation ◽  
Environmental Conditions ◽  
Yangtze River ◽  
Flood Control ◽  
Peak Flow ◽  
Control Design ◽  
Simulation Method ◽  
Design Flow ◽  
The Yangtze River ◽  
Annual Average

In the downstream tidal section of the Yangtze River, nine kinds of combinations of hydrological environmental conditions are considered, including the annual average runoff flow, the annual average peak flow and the flood control design flow, as well as the three conditions of spring, medium and neap tides. By means of the numerical simulation method, the effective performance parameter values for conventional intercepting boom under different environmental conditions are obtained by simulating 9 kinds of maximum current speed to withstand, Max.CS, respectively. The results show that, in the downstream fast current tidal section of the Yangtze River, for the boom performance index of Max.CS, the relatively extensive applicability value should be 3.0kn under the condition of the annual average runoff flow; 4.0Kn should be selected under the condition of the annual average peak flow; and 4.5Kn should be selected under the flood control design flow. This study can provide technical support for the design, selection and use of booms in downstream waters of the Yangtze River.

scholarly journals Multi-Objective Joint Optimal Operation of Reservoir System and Analysis of Objectives Competition Mechanism: A Case Study in the Upper Reach of the Yangtze River

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2542 ◽  
Author(s):  
Mufeng Chen ◽  
Zengchuan Dong ◽  
Wenhao Jia ◽  
Xiaokuan Ni ◽  
Hongyi Yao
Keyword(s):  
Power Generation ◽  
Water Supply ◽  
Yangtze River ◽  
Water Resource Management ◽  
Flood Control ◽  
Optimal Operation ◽  
Total Power ◽  
The Yangtze River ◽  
Multi Objective ◽  
Reservoir System

The multi-objective optimal operation and the joint scheduling of giant-scale reservoir systems are of great significance for water resource management; the interactions and mechanisms between the objectives are the key points. Taking the reservoir system composed of 30 reservoirs in the upper reaches of the Yangtze River as the research object, this paper constructs a multi-objective optimal operation model integrating four objectives of power generation, ecology, water supply, and shipping under the constraints of flood control to analyze the inside interaction mechanisms among the objectives. The results are as follows. (1) Compared with single power generation optimization, multi-objective optimization improves the benefits of the system. The total power generation is reduced by only 4.09% at most, but the water supply, ecology, and shipping targets are increased by 98.52%, 35.09%, and 100% at most under different inflow conditions, respectively. (2) The competition between power generation and the other targets is the most obvious; the relationship between water supply and ecology depends on the magnitude of flow required by the control section for both targets, and the restriction effect of the shipping target is limited. (3) Joint operation has greatly increased the overall benefits. Compared with the separate operation of each basin, the benefits of power generation, water supply, ecology, and shipping increased by 5.50%, 45.99%, 98.49%, and 100.00% respectively in the equilibrium scheme. This study provides a widely used method to analyze the multi-objective relationship mechanism, and can be used to guide the actual scheduling rules.

Insights from the Three Gorges study

1994 ◽  
Vol 21 (4) ◽  
pp. 541-546 ◽  
Author(s):  
S. O. Denis Russell
Keyword(s):  
Yangtze River ◽  
Flood Control ◽  
Three Gorges Project ◽  
Three Gorges ◽  
The Yangtze River ◽  
Professional Groups ◽  
The Three Gorges ◽  
Large Dams ◽  
Different Cultures ◽  
Large Dam

In the late 1980s, a consortium of Canadian engineering companies carried out a study of the proposed Three Gorges project on the Yangtze River in China. Probe International published a stinging critique of the proposed project and the study. The diverging conclusions from the two groups are explained by the fact that the Canadian engineering consortium and Probe represented two completely different cultures: the large dam, heavy civil engineering culture and the "new green culture." It is claimed that the best hope for avoiding similar conflicts over very large projects in future would be to include representatives from all the professional groups involved — environmental scientists, economists, sociologists, and civil engineers — as full members of the coordinating team for the project right from the beginning. Key words: Three Gorges project, large dams, environmental impact, flood control, hydroelectric.

scholarly journals Are only floods with large discharges threatening? Flood characteristics evolution in the Yangtze River Basin

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Suning Liu ◽  
Yi Zheng ◽  
Lian Feng ◽  
Ji Chen ◽  
Venkataraman Lakshmi ◽  
...  
Keyword(s):  
River Basin ◽  
Yangtze River ◽  
Socioeconomic Development ◽  
Flood Control ◽  
Yangtze River Basin ◽  
High Water ◽  
Critical Issue ◽  
Water Levels ◽  
The Yangtze River ◽  
The Yangtze River Basin

AbstractThis study focuses on the evolution of flood risk in the Yangtze River Basin under climate change, which is a critical issue for socioeconomic development in future. In this study, we (1) compared the 1998 and 2020 floods and found that the destructiveness of a given discharge is now greater than before; (2) revealed three issues related to the above finding; and (3) prospected the future development of up-to-date technologies to better address the issue that floods with high water levels will frequently threaten us. The outcomes of this study would be of great significance to future flood control operation of large river basins.

scholarly journals Impacts of Three Gorges Dam's operation on spatial–temporal patterns of tide–river dynamics in the Yangtze River estuary, China

Ocean Science ◽  
2019 ◽  
Vol 15 (3) ◽  
pp. 583-599 ◽  
Author(s):  
Huayang Cai ◽  
Xianyi Zhang ◽  
Min Zhang ◽  
Leicheng Guo ◽  
Feng Liu ◽  
...  
Keyword(s):  
Yangtze River ◽  
Flood Control ◽  
River Estuary ◽  
Temporal Patterns ◽  
Freshwater Discharge ◽  
Yangtze River Estuary ◽  
Three Gorges ◽  
The Yangtze River ◽  
River Dynamics ◽  
The Yangtze River Estuary

Abstract. The Three Gorges Dam (TGD), located in the main stream of the Yangtze River, is the world's largest hydroelectric station in terms of installed power capacity. It was demonstrated that the TGD had caused considerable modifications in the downstream freshwater discharge due to its seasonal operation mode of multiple utilisation for flood control, irrigation, and power generation. To understand the impacts of the freshwater regulation of the TGD, an analytical model is adopted to explore how the operation of the TGD may affect the spatial–temporal patterns of tide–river dynamics in the Yangtze River estuary. We evaluated the effect of the TGD by comparing the changes in major tide–river dynamics in the post-TGD period (2003–2014) with those in the pre-TGD period (1979–1984). The results indicate that the strongest impacts occurred during the autumn and winter, corresponding to a substantial reduction in freshwater discharge during the wet-to-dry transition period and slightly increased discharge during the dry season. The underlying mechanism leading to changes in the tide–river dynamics lies in the alteration of freshwater discharge, while the impact of geometric change is minimal. Overall, the results suggest that the spatial–temporal pattern of tide–river dynamics is sensitive to the freshwater regulation of the TGD, so that the ecosystem function of the estuary may undergo profound disturbances. The results obtained from this study can be used to set scientific guidelines for water resource management (e.g. navigation, flood control, salt intrusion) in dam-controlled estuarine systems.

scholarly journals Effects of the Three Gorges Project on Runoff and Related Benefits of the Key Regions along Main Branches of the Yangtze River

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 269 ◽  
Author(s):  
Yanjun Gao ◽  
Yongqiang Zhang
Keyword(s):  
Yangtze River ◽  
Flood Control ◽  
Three Gorges Project ◽  
Three Gorges ◽  
The Yangtze River ◽  
Annual Fluctuation ◽  
The Core ◽  
The Three Gorges ◽  
Core Areas ◽  
The Three Gorges Project

The Three Gorges Project (TGP) is the largest hydroelectric project in the world. It is crucial to understand the relationship between runoff regime changes and TGP’s full operation after 2009 in the Yangtze River Basin (YRB). This paper defines core, extended and buffer areas of YRB, analyzes the effects of TGP on runoff anomaly (RA), runoff variation (RV) and change of coefficient of variation (CCV) between two periods (2003–2008 and 2009–2016), takes percentage of runoff anomaly (PRA) as the evaluation standard, assures alleviation effect on severe dry and wet years of the research area, and finally summarizes related benefits of flood control from TGP. Our results indicate the inter-annual fluctuation of runoff in the core and extended areas expanded, but reduced in the buffer areas, and the frequencies of severe dry and wet years alleviated in the buffer, core and extended areas. Generally, the extended and core areas become less wet, and the buffer areas become less dry. The RV and CCV are both strengthened in the extended and core areas, but are weakened in the buffer areas, and RV is well positively correlated (R2 = 0.80) to CCV. Furthermore, the main benefits of TGP on flood control are remarkable in the reduction of disaster affected population, the decrease of agricultural disaster-damaged area, and the decline of direct economic loss. However, due to torrentially seasonal and non-seasonal precipitation, the sharp rebounds of three standards for Hubei and Anhui occurred in 2010 and 2016, and the percentage of agricultural damage area of five regions in the core and extended areas did not decline synchronously and performed irregularly. Our results suggest that the five key regions along the main branches of the Yangtze River should establish a flood control system and promote the connectivity of infrastructures at different levels to meet the significant functions of TGP. It is a great challenge for TGP operation to balance the benefits and conflicts among flood control, power generation and water resources supply in the future.

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