Largest Water Conservancy Project Research Articles

Design of Control System of Oil Collection Device

The South-to-North Water Diversion project is a large water conservancy project implemented by the Chinese government to solve the water shortage problem in North China, but the oil slick pollution is an important problem. Aiming at the problem of oil slick pollution, a control system of oil slick collection device is designed in this paper. First of all, the design idea of intercepting first, then collecting, and then separating was determined, and the software was programmed. The simulation of Proteus software showed that the control program was stable and reliable, the pressurizing device could realize manual and automatic control respectively, and the oil-water separation device could realize the control of the three valves.

Influence of large reservoir operation on change patterns of fish community assembly and growth adaption at low and high-water levels

The Three Gorges Dam is the largest water conservancy project in the world, and the Three Gorges Reservoir Area (TGRA) possesses precious fish resources. Currently, due to the lack of efficient biodiversity monitoring tools, the precise evaluation of fish community composition in a riverine reservoir has been restricted. Here, we investigated fish resources using 12S-rDNA barcoding in the TGRA before and after 175 m water level during the first year of a 10-year Yangtze fishing ban. Our results showed that the fish composition exhibited obvious seasonal differences. The environmental water levels, land use, and spatial characteristics less influenced the development of fish communities. Based on Infer Community Assembly Mechanisms (iCAMP) by phylogenetic bin-based null model analysis, 66.12 % of unexplained variables were driven by stochastic processes of community assembly and unmeasured key factors. We developed a growth-limiting index (GLI) and firstly applied it to inferring fish environmental adaptability, revealing the growth adaption response of reservoir fish species to environmental pressure. Compared to the downstream from the dam, fish population growth at the low- or high-water levels was partly inhibited. However, seven species of tiny or medium-sized fish showed strong adaptability in the reservoir region at both water levels. Taken together, this study clarified the patterns of fish community assembly in the TGRA and provided unique insights for chronic monitoring of fish diversities in a reservoir.

Quantitative Analysis of the Influence of the Xiaolangdi Reservoir on Water and Sediment in the Middle and Lower Reaches of the Yellow River

The Xiaolangdi Reservoir is the second largest water conservancy project in China and the last comprehensive water conservancy hub on the mainstream of the Yellow River, playing a vital role in the middle and lower reaches of the Yellow River. To study the effects of the construction of the Xiaolangdi Reservoir (1997-2001) on the runoff and sediment transport in the middle and lower reaches of the Yellow River, runoff and sediment transport data from 1963 to 2021 were based on the hydrological stations of Huayuankou, Gaocun, and Lijin. The unevenness coefficient, cumulative distance level method, Mann-Kendall test method, and wavelet transform method were used to analyze the runoff and sediment transport in the middle and lower reaches of the Yellow River at different time scales. The results of the study reveal that the completion of the Xiaolangdi Reservoir in the interannual range has little impact on the runoff in the middle and lower reaches of the Yellow River and a significant impact on sediment transport. The interannual runoff volumes of Huayuankou station, Gaocun station, and Lijin station were reduced by 20.1%, 20.39%, and 32.87%, respectively. In addition, the sediment transport volumes decreased by 90.03%, 85.34%, and 83.88%, respectively. It has a great influence on the monthly distribution of annual runoff. The annual runoff distribution is more uniform, increasing the runoff in the dry season, reducing the runoff in the wet season, and bringing forward the peak flow. The runoff and Sediment transport have obvious periodicity. After the operation of the Xiaolangdi Reservoir, the main cycle of runoff increases and the second main cycle disappears. The main cycle of Sediment transport did not change obviously, but the closer it was to the estuary, the less obvious the cycle was. The research results can provide a reference for ecological protection and high-quality development in the middle and lower reaches of the Yellow River.

Water Conservation Ecological Service Function and Its Value Response Mechanism in a Nested Water Conservancy Project Area

The Three Gorges Project is the largest water conservancy project in the world. To cope with the ecological problems of the subsidence zone in the Three Gorges Reservoir area, the Kaizhou water-level-regulating dam was built, forming a model of nested water conservancy projects. The Pengxi River Basin is affected not only by this project but also by human activities in the reservoir area and changes in the substratum and hydro-meteorology, which exert influences on the water connotation function and its ecological value through complex mechanisms. In addition, the response mechanism of the changes in the environment is unclear. Therefore, based on the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model and a spatial interpolation method, in this study, two time nodes (2005 and 2018) before and after the operation of the nested water conservancy projects began were selected, and seven simulation scenarios with different water levels, precipitations, and temperatures were created to explore the evolution of the water conservation service function in the nested water conservancy project operation area under the complex changes in the environment. The results reveal that the operation of the water conservancy projects has had some influence on the water content, but the response of the water content function to the precipitation conditions has been more significant. In colder and rainier years, the water content was higher. In contrast, the lowest value occurred in a year with high temperatures and low rainfall. The highest and lowest values were quantitatively different. Therefore, the influences of the complex environmental factors on the regional water connotation service function deserve more attention. The results of this study provide a scientific basis for research on the ecological service function and the value of water conservation in the Three Gorges Reservoir subsidence zone and the nested operation area of the related water conservancy projects, as well as a data reference for the optimal allocation of regional water resources.

Health assessment of important tributaries of Three Georges Reservoir based on the benthic index of biotic integrity

China’s Three Gorges Reservoir (TGR) is the largest water conservancy project in the world, and plays a significant role in flood control and water transport. To study the health status of the tributaries of TGR, we set up 175 sampling sites, including 15 reference sites and 160 impaired sites on 36 important tributaries of TGR, and collected zoobenthos at these sampling sites. We selected 26 candidate metrics, analyzed them in terms of the distribution range, discriminant ability and correlation. Eight core metrics (i.e., total taxa, ephemerida + trichoptera + plecoptera taxa, diptera taxa, ephemerida%, trichoptera%, Shannon–Wiener diversity index, dominant species% and filter%) were identified, and then the benthic indexes of biological integrity (B-IBI) was established. The B-IBI was then used to evaluate the ecological status of 36 tributaries of TGR. Among all the sampling sites, “excellent”, “good”, “fair”, “poor” and “very poor” accounted for 5.14%, 13.14%, 28.00%, 44.57%, and 9.14%, respectively. Among all streams and rivers, “excellent”, “good” “fair”, “poor” and “very poor” accounted for 5.56%, 41.67%, 50.00%, 2.78%, and 0%, respectively, showing a general good condition for all tributaries. There was a significant difference in health status between tributaries in the TGR dam and those in its upper reaches. The B-IBI established in this study can capture the health status of 36 important tributaries of TGR. This study does not only enrich the practice of health assessment using B-IBI, but also provides some reference for the evaluation of similar rivers across the world.

Shift in functional plant groups under flooding impacted ecosystem C and N dynamics across riparian zones in the Three Gorges of China

Large water conservancy project can strongly alter the plant community composition, however, how these changes can potentially affect ecosystem carbon (C) and nitrogen (N) dynamics is not fully understood. Here, we investigated natural 13C and 15N abundance of C3 and C4 plants and soil in different fractions [labile C (LC) and N (LN), recalcitrant C (RC) and N (RN)]from 6 sites with two elevations (flooding zone, 145–175 m, area with revegetation due to flooding, N = 6); and unflooding zone, >175 m with original plant as a control, N = 3) in riparian zones of the Three Gorges Reservoir, China. The dominant species were the C4 plants in the upstream including Changshou (CS), Fuling (FL) and Zhongxian (ZX) and the C3 plants in the downstream in unflooding zone including Wanzhou (WZ) Badong (BD), and Zigui (ZG). C4 plant in flooding zone was significant decreased by mean 25% compared with unflooding zone in the upstream but significantly increased the by mean 59% in the downstream. The 13C isotopic differences between soil and plant (Δδ13C) was lower than zero in both flooding and unflooding in the upstream, but was only lower than zero in flooding zone in the downstream. The proportion of C3-derived C in soil organic carbon pool (average 74.64%) was lower for the flooding zone compared to the unflooding zone (average 87.26%) in most sites, while the proportion of C3-derived C in LC (average 44.38%) was decreased in the flooding zone compared to the unflooding zone (69.52%) in the downstream. Additionally, the δ15N values of soil were higher than plant community in most sites, and were strongly associated with soil C and N pool content, as well as soil pH. Overall, our results revealed that soil C accumulation was primarily determined by C3 plant in situ and new C input by existing dominant C4 plant, whereas soil N dynamics was predictably dependent on soil relative C and N availability in response to flooding at regional scale.

Experimental study on energy dissipation of annular overflow shaft

The annular shaft, which is widely used in tailings and some large and medium water conservancy project, has the characteristics of simple structure and strong discharge capacity. With the increase of working head, the energy dissipation problem of shaft is becoming much important. Model test results shows that the peak of the hydrodynamic pressure at the bottom of the shaft happens when the water jet merge together, for the water depth H in the shaft is low then, the pre-excavated hydrostatic depth is the main factor of energy dissipation. The fitting formula of the maximum impact pressure is obtained and it is suggested that the energy dissipation depth h should be 0.8D.

Study of the flood control scheduling scheme for the Three Gorges Reservoir in a catastrophic flood

AbstractThe Three Gorges Project is the world's largest water conservancy project. According to the design standards for the 1,000‐year flood, flood diversion areas in the Jingjiang reach of the Yangtze River must be utilized to ensure the safety of the Jingjiang area and the city of Wuhan. However, once these areas are used, the economic and life loss in these areas may be very great. Therefore, it is vital to reduce this loss by developing a scheme that reduces the use of the flood diversion areas through flood regulation by the Three Gorges Reservoir (TGR), under the premise of ensuring the safety of the Three Gorges Dam. For a 1,000‐year flood on the basis of a highly destructive flood in 1954, this paper evaluates scheduling schemes in which flood diversion areas are or are not used. The schemes are simulated based on 2.5‐m resolution reservoir topography and an optimized model of dynamic capacity flood regulation. The simulation results show the following. (a) In accord with the normal flood‐control regulation discharge, the maximum water level above the dam should be not more than 175 m, which ensures the safety of the dam and reservoir area. However, it is necessary to utilize the flood diversion areas within the Jingjiang area, and flood discharge can reach 2.81 billion m3. (b) In the case of relying on the TGR to impound floodwaters independently rather than using the flood diversion areas, the maximum water level above the dam reaches 177.35 m, which is less than the flood check level of 180.4 m to ensure the safety of the Three Gorges Dam. The average increase of the TGR water level in the Chongqing area is not more than 0.11 m, which indicates no significant effect on the upstream reservoir area. Comparing the various scheduling schemes, when the flood diversion areas are not used, it is believed that the TGR can execute safe flood control for a 1,000‐year flood, thereby greatly reducing flood damage.

Erosion and deposition within Poyang Lake: evidence from a decade of satellite data

Abstract Poyang Lake, an important wetland in the Ramsar Convention List, is the largest freshwater lake in China and an essential component of the Yangtze River system. The lake is increasingly experiencing serious water crises including seasonal desiccation, decreased wetland area, and water shortages, all of which are closely related to progressive changes in the lake's topography over recent years. Atime-series of bottom topography would contribute to our understanding of the lake's evolution during the past several decades. However, quality bathymetric data for Poyang Lake are scarce owing to the highly dynamic and turbid nature of its water. To resolve this limitation, we used a total of 146 medium-resolution satellite images to build annual and quasi-annual bottom topography maps of Poyang Lake during the period from 2000 to 2010 based on the well-established waterline method. Our results show that: (1)the average elevation of the lakebed relative to sea level has decreased by 14.4 cm/yr. from 2000 to 2010; and (2)the observed annual changes in the lakebed elevation were well correlated (r = 0.84) with measured changes in the lake's annual net sediment flux. The observed trends may be attributed to the impacts of human activities, especially the operation of the Three Gorge Dams, frequent sand mining, and the implementation of a large water conservancy project. This decade-long quantitative understanding of the lake's evolution and bottom topography elevations might assist both researchers and local policymakers in ecological management, wetland protection, and lake navigation safety.

Qingkou complex: an engineering masterpiece of the Grand Canal of China

Situated at the meeting point of the Yellow River, the Huai River and the Grand Canal of China, the Qingkou complex is a large comprehensive water conservancy project built from the sixteenth to nineteenth centuries to solve the problems for the Grand Canal to join the Huai River and cross the Yellow River. Through the World Cultural Heritage nomination of the Grand Canal, the composition, operation mechanism and evolution of Qingkou complex is comprehensively studied. This paper summarises these findings, and maps a complete view of the Qingkou complex – an engineering masterpiece along the Grand Canal of China.

Influence of seasonal runoff regulation by the Three Gorges Reservoir on saltwater intrusion in the Changjiang River Estuary

The Three Gorges Reservoir (TGR) is the largest water conservancy project in the world. It significantly regulates discharge of the Changjiang River on a seasonal scale. It stores water in autumn and drains it during the following dry season. Although the effects of the TGR on various processes in the river, estuary, and adjacent seas have been studied extensively, the TGR's influence on saltwater intrusion around the estuary and its impacts on vital freshwater reservoirs have not been quantitatively evaluated. In this study, we used a well-validated numerical model to simulate the seasonal-scale saltwater intrusion around the Changjiang Estuary under scenarios with and without the TGR regulation. Results showed that during the autumn season, the TGR advanced the timing of saltwater intrusion and slightly increased its intensity. In contrast, as the TGR supplemented river discharge during the dry season, saltwater intrusion around the freshwater reservoirs was significantly suppressed. Moreover, duration of saline water (salinity>0.45, the standard for drinking water) at the Dongfengxisha, Chenhang, and Qingcaosha Reservoirs was shortened by about 16%, 73.1%, and 48%, respectively. The model results showed that overall, operation of the TGR is basically favorable for reducing the burden of freshwater supplement in the high-populated estuarine region.

Thermal Stress Analysis of Large Scale U-Shaped Aqueduct

The aqueduct is one of large scale water conservancy project across river, which is the first level of anti-cracking structure with rigorous control of cracks. At present, the thermal analysis of aqueduct structure most borrows ideas from box-girder bridge structure without considering their difference. As the thermal stress of large-scale concrete structure during construction and operational process is redoubtable, the U-shaped model of a practical aqueduct of South-to-North Water Diversion is established to do the steady and transient thermal analyses. The result shows that the structure of U-shaped aqueduct is reasonable, it is not necessary to take special measures to control the temperature during the construction and operational process.

Hydrological and associated pollution load simulation and estimation for the Three Gorges Reservoir of China

This study demonstrates an integrated study by coupling a NPS pollution load estimation sub-model with a distributed hydrological model to simulate the hydrological processes and associated pollution load processes in the Three Gorges (TG) Reservoir which is the largest water conservancy project in China, and further estimates the pollution loads and their responses to rainfall changes. The distributed hydrological model Easy Distributed Hydrological Model (EasyDHM) is featured as containing easy rain-runoff generation processes, comprehensive pre-process and post-process modules. Based on EasyDHM, this study develops a NPS pollution load estimation sub-model Easy Distributed Non-Point source evaluation sub-model taking both point source (PS) and NPS pollution into consideration. Through the application of the models in the TG area, this study clarifies the mechanism and characteristics of NPS pollution and estimates the pollution loads in the region. This study could provide technical support for the establishment of Best Management Practices for NPS pollution in the region, and references for the government during the processes of formulating and implementing decision-makings on pollution control and comprehensive management in the TG area.

Evolution of Hydro-Climatic Elements in the Three Gorges Reservoir under Changing Environment

Climate change is one of the major global issues commonly concerned by international communities. Taking the Three Gorges Reservoir which is the largest water conservancy project in China as the study area, this study attempts to evaluate the variability of hydro-climatic elements including precipitation, temperature, relative humidity and sunshine hours during past 49 years (1961-2009) based on observed meteorological data, and predict the evolution trends of precipitation, temperature, evapotranspiration and runoff in the future 30 years (2021-2050) under climate change based on a distributed hydrological model and climate model outputs. Specifically, the temporal variations and sudden changes of precipitation, temperature, relative humidity and sunshine hours during past 49 years in the Three Gorges Reservoir are analyzed combining moving-average and linear regression with Mann-Kendall method, and the precipitation and temperature data in the future 30 years are obtained from the average dataset of 20 global climate models using a statistical downscaling model, and the evapotranspiration and runoff data in the future are obtained based on the validated hydrological model. The results indicate that: 1) during 1961-2009, the precipitation slightly decreased and the estimated sudden change time was 1973, the temperature significantly increased and the estimated sudden change time was 1963, the relative humidity decreased but there was no sudden change time estimated, the sunshine hours significantly decreased and the estimated sudden change time was 1967; 2) in the future, comparing with the historical average, the temperature in the region will increase by 1.3°C and the evapotranspiration will increase by 2.8%, while the precipitation and runoff will decrease by 0.8% and 8.2% respectively. Although the precipitation will not change greatly, the reduction extent of runoff is larger than that of precipitation, bringing forward higher requirements for integrated water resources management in the Three Gorges Reservoir.

Experimental and numerical seismic investigations of the Three Gorges dam

The Three Gorges dam project in China is the largest water conservancy project ever built in the world and is also currently the world’s largest construction project [China Yangtze Three Gorges Project Cooperation. A brief introduction on the Three Gorges project on the Yangtze River; 1999. http://www.nickdw.com/3-gorges/DOCS/1999.htm]. A seismic analysis of the powerhouse monolith of the Three Gorges dam is performed through model testing at a geometric scale of 1:100 on a shaking table and numerical simulation using a three-dimensional finite element model of the structure. It is observed from this combined experimental and numerical study that the powerhouse monolith has a relatively high capability for earthquake resistance and satisfies the seismic design requirements of the national code of China [Ministry of Hydraulics and Hydroelectrics. National standard of the People’s Republic of China SDJ10-78: seismic design code of hydraulic structures; 1978]. This study also shows that the seismic responses calculated from the three-dimensional finite element model are in good agreement with those obtained from the model test on the shaking table for the case of an empty reservoir and rigid foundation. The outcome of this study should be of interest and use to professionals involved in the design of large gravity dams.

Three Gorges Project: the largest water conservancy project in the world

AbstractThe Three Gorges Project (TGP) is the largest water conservancy project ever built in China and in the world. Construction of TGP commenced in 1993 and more than half is complete. It is predicted that the project will be put into initial use in 2003, and finished in 2009. This article discusses the project's advantages and some of the challenges faced, including technical, environmental and resettlement issues. Copyright © 2002 John Wiley & Sons, Ltd.

Optimizing the construction sequence of a series of underground openings using dynamic construction mechanics and a rock mass fracture damage model

A constitutive model for a rock mass with intermittent joints and with an evolution equation for the propagation of secondary cracks at joint tips is proposed in this paper using fracture mechanics and damage mechanics. The principle of dynamic construction mechanics of a rock mass is described. The principles of dynamic programming and artificial intelligence techniques, as well as the above mentioned mechanical models, are used to perform optimizing analysis for the construction scheme of a group of chambers for a large water-conservancy project. The results show that the optimizing analysis is effective.