Large-scale Water Conservancy Projects Research Articles

An enhanced multiobjective bacterial foraging algorithm for the compaction parameter optimization of earth-rock dams

Compaction parameters can act as key decision variables. However, there is a lack of research on the optimization of compaction parameters considering quality, time, and costs. Existing algorithms have difficulty coping with this highly complex and nonlinear problem. To address this issue, an enhanced multiobjective bacterial foraging algorithm is proposed for searching the optimal compaction parameters of earth-rock dams. The cost and time are taken as multiple objectives, and the compaction quality is considered the main constraint because it must meet a certain standard. Then, the enhanced multiobjective bacteria foraging algorithm (EMOBFA) is proposed, which integrates multiple intelligent components into the fundamental single-objective bacterial foraging algorithm, including chaotic mapping, an adaptive step, a rotation learning strategy, and quantum computing. This further improves the speed and accuracy of the state-of-the-art multiobjective optimization algorithm. Finally, multiobjective test functions are used to compare the EMOBFA with commonly used multiobjective optimization algorithms to verify its generality, power, and scalability. A real-life large-scale water conservancy project in Southwest China shows that the proposed EMOBFA has realized the optimization of compaction parameters in the prior control of rolling construction.

Disentangling the role of environmental filtering and biotic resistance on alien invasions in a reservoir area.

Large-scale water conservancy projects benefit human life but have modified the landscape and provided opportunities for alien plant invasions. Understanding the environmental (e.g., climate), human-related (e.g., population density, proximity to human activities), and biotic (e.g., native plant, community structure) factors driving invasions is essential in the management of alien plants and biodiversity conservation in areas with intense human pressure. To this end, we investigated the spatial patterns of alien plant species distribution in the Three Gorges Reservoir Area (TGRA) of China and distinguished the role of the external environment and community characteristics in determining the occurrence of alien plants with differing levels of known invasion impacts in China using random forest analyses and structural equation models. A total of 102 alien plant species belonging to 30 families and 67 genera were recorded, the majority being annual and biennial herbs (65.7%). The results showed a negative diversity-invasibility relationship and supported the biotic resistance hypothesis. Moreover, percentage coverage of native plants was found to interact with native species richness and had a predominant role in resisting alien plant species. We found alien dominance was mainly the result of disturbance (e.g., changes in hydrological regime), which drove native plant loss. Our results also demonstrated that disturbance and temperature were more important for the occurrence of malignant invaders than all alien plants. Overall, our study highlights the importance of restoring diverse and productive native communities in resistance to invasion.

Reducing the Risk of Benthic Algae Outbreaks by Regulating the Flow Velocity in a Simulated South-North Water Diversion Open Channel.

The reduction in open-channel flow velocity due to China's South-to-North Water Diversion Project (SNP) increases the risk of benthic algal community blooms resulting in drinking water safety issues. Consequently, it has attracted attention from all walks of life. However, regulatory measures to mitigate the risk of algal blooms and the main risk-causing factors are unclear. This study simulated the river ecosystem of the SNP channel through water diversion. Simulated gradient-increasing river flow velocity affects environmental factors and benthic algal alterations, and can be used to explore the feasibility of regulating the flow velocity to reduce the risk of algal blooms. We found that the algal biomasses in the velocity environments of 0.211 and 0.418 m/s decreased by 30.19% and 39.88%, respectively. Community structure alterations from diatoms to filamentous green algae were 75.56% and 87.53%, respectively. We observed significant differences in biodiversity, especially in terms of richness and evenness. The α diversity index of a species is influenced by physical and chemical environmental factors (especially flow velocity). Our study revealed that flow velocity is the main factor affecting the growth and outbreak of benthic algae. The risk of algal blooms in open channels can be effectively mitigated by regulating the flow velocity. This provides a theoretical basis for ensuring the water safety of large-scale water conservancy projects.

Hydraulic Structure Design of Changzhou Fishway Based on Optimization Calculation of Hydrodynamic Model

The Changzhou Water Conservancy Project is the first large-scale water conservancy project above the Pearl River Estuary, and its location is extremely important. This section of the river has historically been the main channel for the migration and fattening of various fishes in the Pearl River system; in order to meet the requirements of fish in this section, protect these rare fishes and achieve sustainable development and ecological balance of biological diversity. Purpose, it was decided to build a fish building structure and fish channel in the Cheung Chau Water Conservancy Project. The Cheung Chau Fishway has a total length of 1423 m, and the water head difference between the upstream and downstream is 15 m. It is the first large-scale fishway designed in China. The water head difference of domestic fishways is generally below 5.0 m, and there is very little experience to learn from. Since there was not much successful experience in the domestic fishway at that time, and the domestic fishway construction has been out of gear for nearly 30 years, through the safety appraisal and evaluation of the Cheung Chau fishway during the operation period, valuable opinions were summarized, which will be an important reference for future projects. The experience can be used as a reference for similar projects and promotion.

Modified Hydrological Regime on Irrigation and Water Supply in Lake Areas: A Case Study of the Yangtze River–Dongting Lake

Lake systems are of fundamental significance for the ecological environment and social development. Driven by climatic changes and human activities, the hydrological situation of rivers and lakes has been altered considerably, and it has directly affected the reliability of irrigation and water supply in lake areas. In the case of the Yangtze River–Dongting Lake area, the quasi-equilibrium of their hydrological states and water balance have been affected by the operation of the Three Gorges Project that has led to irrigation and water supply problems across the lake area. Ever since, the available water supply in the Dongting Lake area has decreased by 31.5% and 47.7% during the months of September and October, and the overall water level in the lake area has dropped by 0.8–2.0 m. The proportion of domestic and agricultural irrigation water demands to available water supply in the Dongting Lake area is very small, and the decline of water level is the main reason for the lack of water supply in Dongting Lake area, Although the total amount of water in the lake area is still above the water supply threshold, an obvious decreasing trend has been observed in the fulfillment of the demand for both irrigation and water supply in urban and rural regions. Additionally, the fulfillment of secured water supply and irrigation requirements has respectively dropped from 95% to 78% before the operation of the Three Gorges Project to 82% and 46% after it. Meanwhile, the total water shortage increased from 57.683 to 143.607 million cubic meters. By advancing or postponing impoundment schedules, the impact of the Three Gorges Reservoir on irrigation and water supply in the lake area during September and October can be alleviated, and the water supply capacity can be respectively increased by approximately 1.3% and 1.4%. The highlights of this study include the quantification of the impacts of the operation of large-scale water conservancy projects at the level at which the requirements on irrigation and water supply in the lake area are satisfied, and the prediction of the trends for future evolvement. In addition, corresponding strategies that provide a technical reference for the comprehensive regulation and control over water resources and the security of water supply in the river basin are discussed.

Impact of water-sediment regulation on the concentration and transport of dissolved heavy metals in the middle and lower reaches of the Yellow River

Anthropogenic activities in river basins, especially large-scale water conservancy projects, have notably impacted the physical, chemical and ecological environments of estuaries and coastal areas. In this paper, the effects of water and sediment regulation (WSR) on the concentration and transport of heavy metals in the Yellow River were studied based on a continuous daily heavy metal survey in both the middle reaches (Xiaolangdi station) and lower reaches (Lijin station) of the Yellow River during the WSR period in 2019. The results indicated that the variation in the water oxidation-reduction environment of the Xiaolangdi reservoir during the WSR process exerted an important impact on the concentrations of dissolved Cu, Cd, Pb, Cr and As at the Xiaolangdi station but exerted almost no influence on the concentration of dissolved Ni. At Lijin station, the dissolved heavy metal content first increased and then decreased in the first stage, which mainly depended on the release of heavy metals from resuspended sediments. In the second stage, the heavy metal content gradually decreased due to adsorption onto fine particles discharged from the reservoir. The dissolved heavy metal flux during the water-sediment regulation scheme (WSRS) period accounted for 16.9–33.4% of the annual total dissolved heavy metal flux. WSRS changed transport of water and sediment. The dissolved heavy metal concentrations at the Xiaolangdi station were mainly controlled by the discharge of water and sediments from the Xiaolangdi reservoir, while the dissolved heavy metal concentration at the Lijin station was largely affected by the sediments resuspended from downstream riverbeds and the water and sediment scheduling mode of the Xiaolangdi reservoir. Dissolved heavy metal transportation was highly influenced by the WSR process within a short time. Human intervention, especially WSRS operation, apparently alters the natural states of both the mainstream and estuarine environments of the Yellow River.

Modelling the effects of joint operations of water transfer project and lake sluice on circulation and water quality of a large shallow lake

Large-scale water conservancy projects are constructed worldwide to mitigate water shortage problems in lakes and/or to improve water quality. However, it is unclear how a lake’s ecosystem responds to the joint operations of multiple projects. In this study, we take a first step towards investigating the influence of joint operations involving water transfer and lake sluice projects on current patterns and water quality of Lake Chaohu in China. A coupled 3-D hydrodynamic and biochemical model referred to as an EcoLake was configured and validated. Multiple operation scenarios from the eastern and western routines of the Yangtze River to the Lake Chaohu water transfer project (YCWTP) and the Chaohu Sluice (CS) were generated, based on ‘real’ water quality and hydrological processes during a water transfer experiment carried out from 15 July to 8 August 2017. The EcoLake model successfully captured the current patterns at most monitoring sites. Numerical experiment results suggest that the operations of YCWTP led to an acceleration of up to 0.90 cm/s in the lake-wide current speed. The joint operations of YCWTP and CS tend to decrease the nearshore current speed and increase the offshore current speed. The effects of the different operation strategies vary considerably among water quality parameters and lake basins. The effects are more evident for the central and eastern basins in terms of both current speed and water quality. YCWTP potentially help decrease the chlorophyll-a(Chla) concentration during the water transfer processing, but the benefits diminish gradually in the following two months. In contrast, when the YCWTP and CS are operated jointly, Chla concentrations tend to increase during the first five to six days in the central and eastern basins, then decrease continuously until mid-August. From then on, the Chla concentrations remain at stable levels throughout the rest of the simulation. This study provides important guidance for optimal operations of water conservancy projects in Lake Chaohu.

Study on the Long-Term Reliability of the Tangshuiya Reservoir Dam

Du, P. and Wang, Y.Y., 2020. Study on the long-term reliability of the tangshuiya reservoir dam. In: Bai, X. and Zhou, H. (eds.), Advances in Water Resources, Environmental Protection, and Sustainable Development. Journal of Coastal Research, Special Issue No. 115, pp. 556-560. Coconut Creek (Florida), ISSN 0749-0208.Weifang section of the Yellow River Diversion Project is a comprehensive large-scale water conservancy project, which mainly solves the water supply of Weifang, and also uses farmland irrigation, flood control and hydropower generation. The tangshuiya reservoir dam is a gravity earth rock dam. The research on the rheological properties of rock mass in the project area is the basis of analyzing the long-term stability of slope and cavern. The creep pattern under different levels of tri-axial stress has been experimentally studied. A creep damage model is established. By comparing the fitting result with the experimental data, the model can accurately predict the creep characteristics of shale at different stress levels. Based on the research results of this paper, it can provide guidance for flood control and disaster reduction, improve the creep resistance performance of the reservoir dam and river embankment, and avoid major disasters due to creep.

Analysis of the Causes of Cyanobacteria Bloom: A Review

Among water blooms, cyanobacteria bloom occurs over the widest range and is much more harmful than other blooms. Its occurrence in inland water bodies is affected by many factors, such as meteorology, hydrology, and human activities. Therefore, the study of the causes of cyanobacterial bloom has become a major focus of scholars. The China Knowledge Network Journal Database contains 143 papers from China and abroad from the years 2004 to 2019 that are relevant to the study of cyanobacteria bloom. We begin by analyzing keywords in these studies and creating a keyword distribution map which indicates the factors related to the blooms. Based on parameters such as the frequency of words appearing in the text, the full text of each of the 143 papers is analyzed to form a word cloud created by a program written in Python language. After irrelevant terms are eliminated, the word cloud map can reveal potential factors that were not identified by keywords alone. After completing this macro analysis, we examined approximately 100 related papers from the China Knowledge Network Journal Database and Web of Science Database published from 2014 to 2019. Finally, we summarize the main reasons for the outbreak of water blooms. The factors causing blooms can be divided into natural factors and human factors. Among the natural factors are illumination, water temperature and nutrient salt conditions. The human factors are generally related to large-scale water conservancy projects. This paper analyzes and summarizes these factors, and provides a reference to aid in the prevention and treatment of algal blooms. The information in the paper has a certain practical significance for the protection of water environments.

Simulation model for risk analysis of construction progress of water resources and hydropower projects

There are many uncertainties in the construction process of water conservancy and hydropower projects. The risk analysis of project completion should consider the constraints and overlaps of various resource allocations and procedures. A fault tree risk analysis method is used to comprehensively evaluate the risks of various factors affecting the construction progress of the project. A large-scale water conservancy project construction schedule risk estimation model is solved using an appropriate method, which improves the calculation and application of schedule risk estimation, proposes control concepts of baseline schedule risk and revised schedule risk, and is verified using engineering examples.

IMPACT OF THE THREE GORGES WATER CONSERVANCY PROJECT ON RADIOACTIVITY CONCENTRATION LEVELS IN SURROUNDING WATERS.

Large-scale water conservancy projects bear much economic and social significance. However, there is a lack of systematic research on how such projects affect radioactivity levels in regional water bodies. For the first time, the present paper uses data for nearly 10y at different impoundment levels during construction of the dam to analyze changes in water radioactivity concentration levels in China's Three Gorges region, in order to provide a valuable reference for evaluating the impact of large-scale water conservancy projects on radioactivity concentration levels. Results show that gross α, gross β, U, Th, 226Ra, 40K, 90Sr and 137Cs levels in the water bodies of the Three Gorges region fall within normal limits and annual effective dose for the adults, children and infants are below the WHO recommended reference level of 0.1mSv per y. The period where the sample was collected and spatial distribution are the main reasons why some radionuclides are not normally distributed. Different water levels during different periods result in large variations in the levels of certain radionuclides, indicating that water levels can have a strong influence on radionuclide levels in reservoir regions. Hence, when evaluating the impact of large-scale water conservancy projects on radioactivity levels, analysis should be carried out on samples collected during different periods in order to make accurate assessments.

A Study of the Water and Sediment Transport Laws and Equilibrium Stability of Fluvial Facies in the Ningxia Section of the Yellow River under Variable Conditions

Recently, construction of many large-scale water conservancy projects, as well as the vegetation protection and restoration projects in the upper reaches of the Yellow River, have led to serious changes in water inflow processes, sediment inflow processes, and scour and silting situation in the Ningxia section of the Yellow River (NSYR). This study explored the relationship between the sediment scouring and the silting law of the sediment-laden rivers and the equilibrium fluvial facies in the NSYR. The double cumulative curves of the annual silting amounts and annual incoming sediment amounts in the Qingtongxia–Shizuishan section were then established. It has been previously proven the fluvial facies coefficient increases year by year with the increase in the silting amounts in the watercourse, which lead to the evolution of the watercourse toward the wandering reach. The fluvial facies relationships of their cross-sections under an equilibrium state in the NSYR were established using a Yalin fluvial facies method. The Fr values under an equilibrium state and the actual state were analyzed. The results showed the Xiaheyan section was in an equilibrium state, and the Qingtongxia and Shizuishan cross-section were in a scouring state. This conclusion was confirmed by the actual measured results for numerous years.

Study on evaluation index system for ecological effect of water conservancy projects

With the transformation from traditional water conservancy to ecological water conservancy, functions of water conservancy projects have been changed. In addition to meeting the demand of social economy development, the protection and improvement of eco-environment should be taken into account. As the link between water use for human activities and natural water cycle, it is necessary to research on the ecological effect of water conservancy projects. From the perspective of whether to be affected by human activities, ecological effect is divided into natural ecological effect and social ecological effect, a framework of comprehensive evaluation index system for ecological effect is preliminarily constructed. The concept of ecological effect of water conservancy projects is analysed, and three-level ecological effects of water conservancy projects are presented. The three-level evaluation index system for ecological effect of water conservancy projects is built based on the hydrological regime analysis. The quantitative evaluation can be achieved. The method is applied to evaluate the ecological effect of large-scale water conservancy projects in the Weihe River Basin. The results show that the index system is of high applicability, which provides scientific basis for the quantitative evaluation for ecological effect of water conservancy projects and offers a better support to healthy development of river ecosystems.

Comparative Study on the Discrete Model and the Improved Embedded Model of Cooling Water Pipe

Lianghu pump station of a large-scale water conservancy project under construction is characterized by complex structure, large scale and large size of solid body pouring block, while the previous discrete model of cooling water pipe is difficult to be successfully arranged in the concrete grid and requires a large amount of computation. In this paper, the improved embedded model of cooling water pipe, which considers the change of the water temperature in the cooling water pipe, is adopted to simulate the temperature control of the large pump station during the construction period. The results show that, with the help of the measured data, although the error rate of the improved embedded model of cooling water pipe at the highest temperature is 5% higher than that of the discrete model, the calculation efficiency is increased by about 40% in comparison with the discrete model. The comprehensive profit is improved by nearly 35%. It is worth popularizing and applying in the simulation calculation of temperature field of large pump station structure during construction period. Finally, the results of the two pipe models are compared and the relevant suggestions are given.

Process Analysis of Toppling Failure on Anti-dip Rock Slopes Under Seismic Load in Southwest China

Due to complex geological structures and strong crustal activity, geological disasters occur frequently in the upper reaches of the Yalong River, Southwest China. Toppling failure on anti-dip rock slopes is a common phenomenon; in particular, after the Wenchuan earthquake in 2008, numerous landslides caused by toppling deformation occurred in reservoir areas, seriously threatening the construction and operation of large-scale water conservancy projects and hydropower projects. Taking three typical toppling slopes in the basin as research objects, the dynamic behaviour, failure evolution, and failure plane location of toppling failure under seismic waves were investigated by shaking table tests and UDEC simulations. The test results indicated that slope angle and stratum dip angle were both inversely proportional to the stability of the slope in the tested ranges. The failure evolution of toppling on anti-dip rock slopes could be divided into four stages: (1) the development stage of tensile cracks in the strata; (2) the formative stage of tensile cracks at the crest of the slope; (3) the formative stage of toppling zones; and (4) the failure stage. Two equations were proposed to reveal the relationships between the surface peak ground acceleration and the horizontal depth of the failure plane and displacement of the slope surface. The propagation and coalescence of discontinuous cross joint in the slope and the entire failure evolution simulated by the UDEC damage model agreed well with the shaking table test results.

Pollution Characteristic of Ni in Sediments in the Three Gorges Reservoir

The Three Gorges Reservoir (TGR) has achieved the target of water storage of 175 m for eight consecutive years until October 2017. To study the temporal and spatial variation of nickel (Ni) in different water periods under 175 m operating conditions in the TGR area, probe the impact of a large-scale water conservancy project on the Ni enrichment, and establish the pollution evaluation system of Ni in the TGR area, we collected 173 surface sediment samples from the TGR area during four consecutive water periods from December 2015 to June 2017 and measured the Ni concentration by using inductively coupled plasma mass spectrometry (ICP-MS). The mean values of Ni in the four water periods are higher than the background value of Yangtze sediment and soil. At the spatial scale, the Ni content in the mainstream exhibits a clear upward trend from upstream to downstream and is lower than that of the tributary. The tributaries of the lower reaches shows a notably higher Ni content than the tributaries of the upper and middle reaches. At the temporal scale, the water period exerts an insignificant effect on the Ni content. The Ni content is relatively stable and shows a downward tendency at a 175 m water level. The regional geochemical baseline (RGB) value of Ni was obtained through building a geochemical baseline model in the area. The RGB values of Ni in sediments during four consecutive water periods are 47.0, 44.2, 42.9, and 41.9 mg·kg-1, respectively. The Ni contents in the middle and lower reaches of the mainstream and tributary are significantly affected by human activities. Moreover, the pollution evaluations based on global Ni background values, local background values, and geochemical baseline values as reference values were compared and the geoaccumulation index and potential ecological risk of Ni were determined to comprehensively assess its pollution risk. The assessment data indicate that Ni in the aquatic environment of the TGR area is almost uncontaminated and poses a low ecological risk, except for samples in regions around Fengdu County and Guizhou Town in the Zigui County along the mainstream, which were uncontaminated to moderately contaminated. Relative to global and regional background values, the pollution assessment results obtained using the RGB as a reference value are more scientific and better match the temporal and spatial variation of the study area.

Recent Change of Runoff and Sediment Characteristics of the Jinshajiang River

Sediment load of the Yangtze River is mainly from the upper reaches. The mean annual runoff of the Yichang hydrometric station, where the Three Gorges Project locates, is 436.4 billion m3, and the annual sediment discharge is 470 billion kg. The suspended sediment mainly comes from the Jinshajiang River and the Jialingjiang River. The total mean annual sediment load of these two rivers occupies about 75% of the Yichang station. Compared with the years before 1990, the region composition of the runoff at Yichang station has no obvious variations, while the composition of the sediment source changes distinctly. Due to a large number of hydraulic constructions, the sediment transportation of the Jialinjiang River reduced greatly, whose proportion of the Yichang station has dropped from about 27% to around 10%. The Jinshajiang River basin has become the major area, from which the sediment into the Three Gorges Project comes. In this paper, a long time series of runoff and sediment observations from 1955 to 2011 of the Jinshajiang River is used for characteristics analysis, including trend, jumpy point and the sediment transportation properties. Besides descriptive statements, some statistical analysis techniques, such as Mann Kendall rank correlation test, Fisher ordered clustering, and double mass curves analysis are applied. The results illustrate that the sediment discharge varies with the runoff, displaying a decrease tendency over long time, especially in recent years, the sediment load drops significantly. Meanwhile, the sediment transportation efficiency reduces obviously in recent 10 years, which means much less sediment load can be carried with the same runoff. The construction of the large-scale water conservancy project is the main reason for such drastic change.

Emergency Water Conveyance Project into Dalian Cost Benefit Analysis

The project of transporting water to Dalian in urgent situation is a large-scale Inter-basin water transfer project, which in order to solve the serious problem of the shortage of water in Dalian. It is a key construction project in Liaoning province project, which will cost huge investment and need spending long construction period. Dalian is of great shortage of water resource, it's water supply depends on the Largescale water conservancy project. In order to provide reference to investment and construction of similar project in the future, this paper use the benefit factor analysis and set a model, to analyze the factors, such as economic, social impact, environmental impact. If the construction and use of the funds put into operation, we concluded that the construction of the project was reasonable in economy. The construction of this project will solve water shortage problems periodically and play a significant role in the future of urban development in Dalian.

Profiling of Sediment Microbial Community in Dongting Lake before and after Impoundment of the Three Gorges Dam.

The sediment microbial community in downstream-linked lakes can be affected by the operation of large-scale water conservancy projects. The present study determined Illumina reads (16S rRNA gene amplicons) to analyze and compare the bacterial communities from sediments in Dongting Lake (China) before and after impoundment of the Three Gorges Dam (TGD), the largest hydroelectric project in the world. Bacterial communities in sediment samples in Dongting Lake before impoundment of the TGD (the high water period) had a higher diversity than after impoundment of the TGD (the low water period). The most abundant phylum in the sediment samples was Proteobacteria (36.4%–51.5%), and this result was due to the significant abundance of Betaproteobacteria and Deltaproteobacteria in the sediment samples before impoundment of the TGD and the abundance of Gammaproteobacteria in the sediment samples after impoundment of the TGD. In addition, bacterial sequences of the sediment samples are also affiliated with Acidobacteria (11.0% on average), Chloroflexi (10.9% on average), Bacteroidetes (6.7% on average), and Nitrospirae (5.1% on average). Variations in the composition of the bacterial community within some sediment samples from the river estuary into Dongting Lake were related to the pH values. The bacterial community in the samples from the three lake districts of Dongting Lake before and after impoundment of the TGD was linked to the nutrient concentration.

Three Dimensional Visualization Technologies for Water Conservancy Works

The advances in the study of three dimensional (3D) interactive visualization techniques in hydraulic engineering are reviewed. Main contents, key technologies and the difficulties with their solutions in the application of 3D interactive visualization techniques to water conservancy works are analyzed and summarized. A true 3D visual simulation system prototype for large-scale water conservancy project was built. A framework for building 3D visual simulation system for complex field data in hydraulic engineering is presented to illustrate potentiality and effectiveness of 3D visualization techniques for hydraulic engineering. Aspects like navigation and presentations of complex field data with spatial dependence are presented.