Volume 23,2025 Issue 1
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- Featured Articles
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- Water circulation response and water demand situation change under “DoubleCarbon” strategy
- Research progress and the prospect of a complex relationshipbetween water-energy-carbon emission
- Carbon dioxide emission equivalent analysis method of water resource behaviorsand its application
- Innovation and design of incremental water rights conversion mode in water diversion project intake area
- Ecological regulation of algae in Middle Route of South-to-North Water Diversion Project
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- Practice and countermeasures of the great protection of the Yangtze River
- Driving effect evolution and spatial differentiation of water use change in China
- Simulation of pipeline network drainage at urban community scales based on SWMM:A case study in Fuzhou City
- Interaction mechanism between urbanization and ecological security in nine provinces of the Yellow River basin
- Urban waterlogging simulation and rainwater pipe network system evaluation based on SWMM and SCS method
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Abstract:
Addressing the uneven distribution of water resources and improving water ecological degradation, long-distance water transfer and cross-basin diversion through canal systems are effective approaches. The level of automation control of flow structures during water transfer directly impacts the efficiency of water distribution. With the rapid development of automation technology and continuous innovation in canal water transfer engineering techniques, canal water transfer control algorithms have been increasingly applied in practical water transfer projects. However, despite the expanding scope and depth of their application, a comprehensive and systematic development and test system for canal water transfer control algorithms has not yet been established, which affects the reliability of the algorithms to a certain degree. Various canal water transfer control algorithms that have not been fully developed and rigorously tested may not guarantee sufficient accuracy and stability when applied in the field under various working conditions. A hydrodynamic numerical simulation model and a canal water transfer simulation controller were established based on the current status of the research area. A model-in-the-loop (MIL) test system was designed and developed for the canal water transfer control system. This MIL test system provides technical support for improving the accuracy of canal water transfer control algorithms, reducing development costs, and achieving fine management of water distribution. Firstly, a one-dimensional hydrodynamic numerical simulation model was established. By discretizing the Saint-Venant equations using the Preissmann four-point implicit difference scheme, the unsteady flow conditions in the canal were described. Meanwhile, the internal boundaries such as sluice gates and water outlets were generalized into corresponding control equations using the mass conservation equation and flow-discharge relationships, coupled with the discretized Saint-Venant equations to establish a one-dimensional hydrodynamic numerical simulation model with regulatory structures. The model parameters were calibrated to achieve continuous spatial and temporal simulation of flow and water level during water distribution.Secondly, an automated real-time control system for the canal was established. Based on the operation modes of the gates and control basins in the study area, PI (proportional-integral) and MPC (model predictive control) simulation controllers were developed using genetic algorithms. The established simulation controllers took the opening degree of the sluice gates as the system output, generating real-time control variables for the local end. The simulation controllers were deeply coupled with the hydrodynamic numerical model, forming a closed-loop control at the model level, considering different control conditions under various working conditions.Lastly, the design and implementation of the MIL testsystem were completed. Taken the control algorithms in the canal automation control system as the test objects, the system configuration was developed based on LabVIEW, utilizing the hydrodynamic model as the environmental simulation model to achieve closed-loop test. The main contents included system configuration design, real-time invocation of the control model, and data storage, transmission, and communication with the MySQL database. Through testing in the MIL test system, the control algorithm established can effectively solve real-time canal control issues. The testing environment can be used to test the development of canal water transfer control algorithms, and the control algorithms can be replaced according to needs, satisfying the testing of different control algorithms. This study provides important technical support for the development and testing of control models in the field of canal water transfer engineering. MIL test can greatly improve the quality of control models, ensuring the reliability of canal water transfer control models in various working conditions, laying a solid foundation for improving the operational efficiency and safety of water transfer projects.
Addressing the uneven distribution of water resources and improving water ecological degradation, long-distance water transfer and cross-basin diversion through canal systems are effective approaches. The level of automation control of flow structures during water transfer directly impacts the efficiency of water distribution. With the rapid development of automation technology and continuous innovation in canal water transfer engineering techniques, canal water transfer control algorithms have been increasingly applied in practical water transfer projects. However, despite the expanding scope and depth of their application, a comprehensive and systematic development and test system for canal water transfer control algorithms has not yet been established, which affects the reliability of the algorithms to a certain degree. Various canal water transfer control algorithms that have not been fully developed and rigorously tested may not guarantee sufficient accuracy and stability when applied in the field under various working conditions. A hydrodynamic numerical simulation model and a canal water transfer simulation controller were established based on the current status of the research area. A model-in-the-loop (MIL) test system was designed and developed for the canal water transfer control system. This MIL test system provides technical support for improving the accuracy of canal water transfer control algorithms, reducing development costs, and achieving fine management of water distribution. Firstly, a one-dimensional hydrodynamic numerical simulation model was established. By discretizing the Saint-Venant equations using the Preissmann four-point implicit difference scheme, the unsteady flow conditions in the canal were described. Meanwhile, the internal boundaries such as sluice gates and water outlets were generalized into corresponding control equations using the mass conservation equation and flow-discharge relationships, coupled with the discretized Saint-Venant equations to establish a one-dimensional hydrodynamic numerical simulation model with regulatory structures. The model parameters were calibrated to achieve continuous spatial and temporal simulation of flow and water level during water distribution.Secondly, an automated real-time control system for the canal was established. Based on the operation modes of the gates and control basins in the study area, PI (proportional-integral) and MPC (model predictive control) simulation controllers were developed using genetic algorithms. The established simulation controllers took the opening degree of the sluice gates as the system output, generating real-time control variables for the local end. The simulation controllers were deeply coupled with the hydrodynamic numerical model, forming a closed-loop control at the model level, considering different control conditions under various working conditions.Lastly, the design and implementation of the MIL testsystem were completed. Taken the control algorithms in the canal automation control system as the test objects, the system configuration was developed based on LabVIEW, utilizing the hydrodynamic model as the environmental simulation model to achieve closed-loop test. The main contents included system configuration design, real-time invocation of the control model, and data storage, transmission, and communication with the MySQL database. Through testing in the MIL test system, the control algorithm established can effectively solve real-time canal control issues. The testing environment can be used to test the development of canal water transfer control algorithms, and the control algorithms can be replaced according to needs, satisfying the testing of different control algorithms. This study provides important technical support for the development and testing of control models in the field of canal water transfer engineering. MIL test can greatly improve the quality of control models, ensuring the reliability of canal water transfer control models in various working conditions, laying a solid foundation for improving the operational efficiency and safety of water transfer projects.
Abstract:
Open channel water diversion project is important to solve the regional water shortage problems. However, due to the changes in water supply demand along the line and frequent changes in upstream flow during the operation of the project, the water conditions along the line are complex and variable, which can result in fluctuations in the channel water level and affect the stability of the system. As a controlled system with self balancing ability, the open channel water diversion project can withstand a certain degree of external disturbance through its own self balancing ability when not under control, while meeting the conditions of safe operation of the project. Studying the safety threshold and variation law of this disturbance is of great significance for guiding the control gates. A one-dimensional unsteady hydrodynamic model of coupled control gates was developed to simulate potential disturbance scenarios that may arise during engineering operations. The model calculated the changes in water levels in front of the gate under various disturbance intensities. Based on the safety constraints for water levels, we determined the disturbance threshold that the water conveyance system can tolerate under different working conditions. A fast calculation formula was constructed based on the relationship between upstream flow rate, regulating gate opening, and safety disturbance threshold calculation results. It can be endured under different initial working conditions, providing a discrimination basis for whether to enable regulating gate control. The study focuses on four control gates from the inlet cut-off gate of Diaohe aqueduct to the inverted siphon outlet of Qihe in the middle route of the South-to-North Water Transfers Project , as well as the upstream and downstream channels of each control gate. Different initial operating conditions are set for calculation. The results show that the self balancing ability mainly depends on the overcurrent characteristics of the regulating gate. When both the downstream water level and the position of the regulating gate remain unchanged, the disturbance threshold decreases as the upstream boundary flow increases, indicating a reduction in self balancing capability. In contrast, when the upstream flow boundary and downstream water level are held constant, an increase in the gate opening leads to a higher disturbance threshold, thereby enhancing the self balancing ability. The average error between the constructed fast calculation formula and the model calculation results is less than 0.7 m3/s. The self balancing ability and safety disturbance threshold of the canal pool are closely related to the overcurrent characteristics of the regulating gate, which is mainly influenced by the water level difference before and after the gate, as well as the gate opening. The larger the gate opening and the initial water level difference, the higher the safety disturbance threshold, and the greater the disturbance amount that the canal pool can withstand. This study is applicable to other canal sections of the South-to-North Water Transfers Project and can provide support for scheduling decisions in water transfer projects.
Open channel water diversion project is important to solve the regional water shortage problems. However, due to the changes in water supply demand along the line and frequent changes in upstream flow during the operation of the project, the water conditions along the line are complex and variable, which can result in fluctuations in the channel water level and affect the stability of the system. As a controlled system with self balancing ability, the open channel water diversion project can withstand a certain degree of external disturbance through its own self balancing ability when not under control, while meeting the conditions of safe operation of the project. Studying the safety threshold and variation law of this disturbance is of great significance for guiding the control gates. A one-dimensional unsteady hydrodynamic model of coupled control gates was developed to simulate potential disturbance scenarios that may arise during engineering operations. The model calculated the changes in water levels in front of the gate under various disturbance intensities. Based on the safety constraints for water levels, we determined the disturbance threshold that the water conveyance system can tolerate under different working conditions. A fast calculation formula was constructed based on the relationship between upstream flow rate, regulating gate opening, and safety disturbance threshold calculation results. It can be endured under different initial working conditions, providing a discrimination basis for whether to enable regulating gate control. The study focuses on four control gates from the inlet cut-off gate of Diaohe aqueduct to the inverted siphon outlet of Qihe in the middle route of the South-to-North Water Transfers Project , as well as the upstream and downstream channels of each control gate. Different initial operating conditions are set for calculation. The results show that the self balancing ability mainly depends on the overcurrent characteristics of the regulating gate. When both the downstream water level and the position of the regulating gate remain unchanged, the disturbance threshold decreases as the upstream boundary flow increases, indicating a reduction in self balancing capability. In contrast, when the upstream flow boundary and downstream water level are held constant, an increase in the gate opening leads to a higher disturbance threshold, thereby enhancing the self balancing ability. The average error between the constructed fast calculation formula and the model calculation results is less than 0.7 m3/s. The self balancing ability and safety disturbance threshold of the canal pool are closely related to the overcurrent characteristics of the regulating gate, which is mainly influenced by the water level difference before and after the gate, as well as the gate opening. The larger the gate opening and the initial water level difference, the higher the safety disturbance threshold, and the greater the disturbance amount that the canal pool can withstand. This study is applicable to other canal sections of the South-to-North Water Transfers Project and can provide support for scheduling decisions in water transfer projects.
Abstract:
Water is regarded as a fundamental resource for human society's development. China is recognized as one of the 21 most water-poor and water-scarce countries in the world. This is particularly evident in the Yellow River Basin, where there is a significant imbalance between water supply and demand. To mitigate the water scarcity in the northern region, China constructed the South-to-North Water Transfers Project (SNWTP), thus representing a cross-basin and cross-regional water resources allocation initiative. The severe water shortage predicament in the receiving areas was notably improved by the opening of both the central and eastern routes of the SNWTP. Furthermore, as China progressed with its industrialization and urbanization, a substantial portion of agricultural water was redirected towards non-agricultural purposes, thereby driving an ongoing increase in non-agricultural water demand. Considering the exogenous impact of the SNWTP, it had the potential to either stimulate or hinder the non-agriculturalization of water resources in the receiving areas, while simultaneously addressing water resource constraints. As a result, to empirically investigate, the precise impact of the opening of the SNWTP on the non-agriculturalization of water resources in the receiving areas remained uncertain and warranted further investigation. The impact of the opening of the SNWTP on the non-agriculturalization of water resources in the receiving areas is assessed in terms of scale and degree using a time-varying differences-in-differences model based on provincial panel data from the year 2003 to 2021. Robustness tests such as parallel trend test, placebo test, exclusion of other policy interferences, propensity score matching, controlling for time trend, heterogeneity treatment effect and Bacon decomposition are conducted on this basis. The opening of the SNWTP has been shown to have a positive impact on both the scale and degree of non-agricultural water resource use in the receiving areas. Robust tests have confirmed that this conclusion is consistently valid. The primary mechanism behind this effect is the increase in surface water and other water supplies, while the impact on groundwater was found to be negligible. Furthermore, significant regional differences exist in how the SNWTP influences non-agricultural water resource use. The project has a notably stronger effect on the central route compared to the eastern route. Additionally, the specific impacts of the project include an increase in industrial water usage and a decrease in agricultural water usage. Over time, the cumulative effects of the SNWTP on the de-agriculturalization of water resources in the receiving areas are evident in GDP growth, an increase in the hierarchical coefficient of the industrial structure, and positive changes in both surface and groundwater levels. It is recommended to strengthen the rational use of non-agricultural water to promote industrial development. Surface water protection should be strengthened and a sound water resources management system should be established. The water resource management in the central line area should be strengthened and the cross-border management of water resources should be promoted. Finally, the structure of industrial water use is optimized, the management of domestic water use is strengthened, the ecological protection and restoration is reinforced, and the efficiency of agricultural water use is improved. The empirical evidence provided by the findings of this paper can be used to promote the high-quality development of the SNWT follow-up project. Further exploration could be conducted in follow-up studies regarding the impacts of the SNWTP on quality and efficiency issues of non-agricultural water use in the receiving areas, the long-term impacts of the SNWTP on local ecosystems, and the impacts of the SNWT on food security.
Water is regarded as a fundamental resource for human society's development. China is recognized as one of the 21 most water-poor and water-scarce countries in the world. This is particularly evident in the Yellow River Basin, where there is a significant imbalance between water supply and demand. To mitigate the water scarcity in the northern region, China constructed the South-to-North Water Transfers Project (SNWTP), thus representing a cross-basin and cross-regional water resources allocation initiative. The severe water shortage predicament in the receiving areas was notably improved by the opening of both the central and eastern routes of the SNWTP. Furthermore, as China progressed with its industrialization and urbanization, a substantial portion of agricultural water was redirected towards non-agricultural purposes, thereby driving an ongoing increase in non-agricultural water demand. Considering the exogenous impact of the SNWTP, it had the potential to either stimulate or hinder the non-agriculturalization of water resources in the receiving areas, while simultaneously addressing water resource constraints. As a result, to empirically investigate, the precise impact of the opening of the SNWTP on the non-agriculturalization of water resources in the receiving areas remained uncertain and warranted further investigation. The impact of the opening of the SNWTP on the non-agriculturalization of water resources in the receiving areas is assessed in terms of scale and degree using a time-varying differences-in-differences model based on provincial panel data from the year 2003 to 2021. Robustness tests such as parallel trend test, placebo test, exclusion of other policy interferences, propensity score matching, controlling for time trend, heterogeneity treatment effect and Bacon decomposition are conducted on this basis. The opening of the SNWTP has been shown to have a positive impact on both the scale and degree of non-agricultural water resource use in the receiving areas. Robust tests have confirmed that this conclusion is consistently valid. The primary mechanism behind this effect is the increase in surface water and other water supplies, while the impact on groundwater was found to be negligible. Furthermore, significant regional differences exist in how the SNWTP influences non-agricultural water resource use. The project has a notably stronger effect on the central route compared to the eastern route. Additionally, the specific impacts of the project include an increase in industrial water usage and a decrease in agricultural water usage. Over time, the cumulative effects of the SNWTP on the de-agriculturalization of water resources in the receiving areas are evident in GDP growth, an increase in the hierarchical coefficient of the industrial structure, and positive changes in both surface and groundwater levels. It is recommended to strengthen the rational use of non-agricultural water to promote industrial development. Surface water protection should be strengthened and a sound water resources management system should be established. The water resource management in the central line area should be strengthened and the cross-border management of water resources should be promoted. Finally, the structure of industrial water use is optimized, the management of domestic water use is strengthened, the ecological protection and restoration is reinforced, and the efficiency of agricultural water use is improved. The empirical evidence provided by the findings of this paper can be used to promote the high-quality development of the SNWT follow-up project. Further exploration could be conducted in follow-up studies regarding the impacts of the SNWTP on quality and efficiency issues of non-agricultural water use in the receiving areas, the long-term impacts of the SNWTP on local ecosystems, and the impacts of the SNWT on food security.
Abstract:
Over a hundred water transfer projects have been implemented to address the disparity between the spatial distribution of water resources and economic and social development patterns in China, notably the Eastern and Middle Route of South-to-North Water Transfers Project. These projects are vital for supporting sustainable economic and social development. The integration of cross-basin and cross-regional water transfer projects with local water source projects forms a complex multi-water source system, which involves multiple regions, projects, users, as well as departments, which results in large-scale, multi-objective nonlinear programming challenges. Traditional simulation or optimization methods struggle to balance solution efficiency with optimization performance. Hence, studying simulation-optimization coupling algorithms is a practical approach to enhance calculation efficiency and ensure effective water resource utilization. This study examines the allocation sequence of local and external water resources, and proposes a dual-layer coupling solution algorithm for multi-water source scheduling. The algorithm first uses simulation methods to address local water source allocation (upper-layer algorithm), employing a uniform water supply mode to calculate the ideal optimal water supply quantity and adjust constraint violations period by period. Subsequently, a large-scale system decomposition and coordination method is used to manage external water allocation (lower-layer algorithm) based on upper-layer scheduling results. By introducing coordination variables to decouple system correlation constraints, the original complex system is transformed into multiple simpler subsystems, with optimal solutions obtained through feedback and iteration between subsystems and the coordination layer. A multi-objective optimization model for water quantity scheduling was developed in the Eastern Route of South-to-North Water Transfers Project area. The optimization goals were to minimize the total weighted water shortage rates of users in the receiving area and the overall amount of water transferred from the source. The simulation-optimization dual-layer coupling algorithm was employed to solve the problem, and its effectiveness was verified. Results for the typical dry year of 1992 showed that: (1) With a Yangtze River flow of 4.364 billion m3, the water demand of the receiving area can be met by prioritizing surplus local runoff from Hongze Lake and Dongping Lake; (2) Diverting 2.5 billion m3 of water from the Yangtze River can reduce the comprehensive water shortage rate in the receiving area to 16.52%. This water quantity scheduling plan is a coordinated approach addressing both water shortage and diversion; (3) The simulation-optimization dual-layer coupling algorithm, combined with constraint relaxation, local water source simulation, and large-scale system decomposition and coordination, effectively reduces the computational complexity of cross-basin water transfer system scheduling problems while ensuring optimization performance. The layered calculation demonstrates that the joint allocation relationship between local and external water transfers, thus improving the interpretability of multi-source scheduling results. The algorithm provides a reference for solving multi-objective water quantity scheduling problems in large-scale cross-basin water transfers.
Over a hundred water transfer projects have been implemented to address the disparity between the spatial distribution of water resources and economic and social development patterns in China, notably the Eastern and Middle Route of South-to-North Water Transfers Project. These projects are vital for supporting sustainable economic and social development. The integration of cross-basin and cross-regional water transfer projects with local water source projects forms a complex multi-water source system, which involves multiple regions, projects, users, as well as departments, which results in large-scale, multi-objective nonlinear programming challenges. Traditional simulation or optimization methods struggle to balance solution efficiency with optimization performance. Hence, studying simulation-optimization coupling algorithms is a practical approach to enhance calculation efficiency and ensure effective water resource utilization. This study examines the allocation sequence of local and external water resources, and proposes a dual-layer coupling solution algorithm for multi-water source scheduling. The algorithm first uses simulation methods to address local water source allocation (upper-layer algorithm), employing a uniform water supply mode to calculate the ideal optimal water supply quantity and adjust constraint violations period by period. Subsequently, a large-scale system decomposition and coordination method is used to manage external water allocation (lower-layer algorithm) based on upper-layer scheduling results. By introducing coordination variables to decouple system correlation constraints, the original complex system is transformed into multiple simpler subsystems, with optimal solutions obtained through feedback and iteration between subsystems and the coordination layer. A multi-objective optimization model for water quantity scheduling was developed in the Eastern Route of South-to-North Water Transfers Project area. The optimization goals were to minimize the total weighted water shortage rates of users in the receiving area and the overall amount of water transferred from the source. The simulation-optimization dual-layer coupling algorithm was employed to solve the problem, and its effectiveness was verified. Results for the typical dry year of 1992 showed that: (1) With a Yangtze River flow of 4.364 billion m3, the water demand of the receiving area can be met by prioritizing surplus local runoff from Hongze Lake and Dongping Lake; (2) Diverting 2.5 billion m3 of water from the Yangtze River can reduce the comprehensive water shortage rate in the receiving area to 16.52%. This water quantity scheduling plan is a coordinated approach addressing both water shortage and diversion; (3) The simulation-optimization dual-layer coupling algorithm, combined with constraint relaxation, local water source simulation, and large-scale system decomposition and coordination, effectively reduces the computational complexity of cross-basin water transfer system scheduling problems while ensuring optimization performance. The layered calculation demonstrates that the joint allocation relationship between local and external water transfers, thus improving the interpretability of multi-source scheduling results. The algorithm provides a reference for solving multi-objective water quantity scheduling problems in large-scale cross-basin water transfers.
Abstract:
Securing water quality for long-distance water transfer initiatives is imperative for the enduring leveraging of the integrated benefits of such hydrological engineering endeavors. The South-to-North Water Transfers Project stands as the most extensive multipurpose water transfer scheme to date. A rigorous and systematic investigation into the water quality assurance strategies for the South-to-North Water Transfers Project is pivotal in offering critical insights and technological underpinnings for the water quality preservation in trans-basin water diversion undertakings. Over the decade since the full operation of the first phase of the South-to-North Water Transfers Project, the project has been running smoothly with continuously excellent water quality. The water quality of the first phase of Middle Route has remained stable at or above the Surface Water Category Ⅱ standards, while the Eastern Route’s first phase has continuously maintained Surface Water Category Ⅲ standards. This has provided a substantial supply of high-quality water to the recipient areas, yielding significant economic, social, and ecological benefits. It is of great responsibility and importance to plan, organize, and implement water quality safety assurance for the South-to-North Water Transfers Project in the new era. This paper systematically reviewed the practical experience gained in ensuring water quality safety in the first phase of the South-to-North Water Transfers Project. Over the decade since the full operation, the project’s operational management organizations have preliminary established a water quality monitoring system, continuously improved the water quality protection system, steadily advanced the prevention and control of water quality risks, and persistently enhanced emergency response capabilities. Robust efforts have been made in providing scientific and technological support, thereby establishing an initial framework for water quality safety assurance , and effectively enhancing the capability to ensure water quality safety. Over the decade, the role of the South-to-North Water Transfers Project has shifted from a supplementary to a primary one. The national requirements for water quality safety have continuously increased, presenting the project with new challenges and difficulties in ensuring water quality safety. Firstly, there is an urgent need to comprehensively upgrade the monitoring and control system for the aquatic ecological environment. The current aquatic ecological monitoring in the South-to-North Water Transfers Project is in its initial stage, and further optimization of monitoring indicators and frequencies is required. Additionally, the foundation for monitoring emerging pollutants such as endocrine disruptors, antibiotics, and microplastics, which are of national concern, is relatively weak. Secondly, the interlinkage mechanism for water quality protection requires immediate refinement and improvement. Engineering operation and management entities need to further refine the mechanisms for government-enterprise coordination and vertically integrated pollution prevention and control. Thirdly, the capacity for risk prevention and control of water pollution needs to be enhanced.The project still faces risks and hidden dangers to water quality safety, including hazardous chemical transport accidents at bridge crossings, external water entering the canal, internal discharge of groundwater, damage to pipelines crossing oil-contaminated areas, and navigation-related risks. Fourthly, the emergency response capability for sudden water pollution incidents requires strengthening and enhancement. Fifthly, there is an urgent need to coordinate and lead the development of a scientific and technological support system for water quality protection. Confronted with the new situation and requirements, the project operation and management organizations were required to further improve the water quality safety assurance system and enhance management effectiveness. This paper planned the water quality safety assurance work for the project in the new era, aiming to refine and enhance the high-quality water quality protection system. It specifically proposed the next steps in five areas: water quality monitoring, protection system, risk prevention and control, emergency response, and scientific and technological support. These steps included continuously improving the monitoring and control capabilities for water quality and aquatic ecology, promoting the construction of a coordinated mechanism for water quality safety assurance, strengthening the dynamic management of pollution risk sources along the route, enhancing emergency response capabilities, and maintaining scientific and technological support for water quality protection. The research findings provided effective support for ensuring the water quality safety of the South-to-North Water Transfers Project and subsequent projects, safeguarding the continuous flow of clear water to the north.
Securing water quality for long-distance water transfer initiatives is imperative for the enduring leveraging of the integrated benefits of such hydrological engineering endeavors. The South-to-North Water Transfers Project stands as the most extensive multipurpose water transfer scheme to date. A rigorous and systematic investigation into the water quality assurance strategies for the South-to-North Water Transfers Project is pivotal in offering critical insights and technological underpinnings for the water quality preservation in trans-basin water diversion undertakings. Over the decade since the full operation of the first phase of the South-to-North Water Transfers Project, the project has been running smoothly with continuously excellent water quality. The water quality of the first phase of Middle Route has remained stable at or above the Surface Water Category Ⅱ standards, while the Eastern Route’s first phase has continuously maintained Surface Water Category Ⅲ standards. This has provided a substantial supply of high-quality water to the recipient areas, yielding significant economic, social, and ecological benefits. It is of great responsibility and importance to plan, organize, and implement water quality safety assurance for the South-to-North Water Transfers Project in the new era. This paper systematically reviewed the practical experience gained in ensuring water quality safety in the first phase of the South-to-North Water Transfers Project. Over the decade since the full operation, the project’s operational management organizations have preliminary established a water quality monitoring system, continuously improved the water quality protection system, steadily advanced the prevention and control of water quality risks, and persistently enhanced emergency response capabilities. Robust efforts have been made in providing scientific and technological support, thereby establishing an initial framework for water quality safety assurance , and effectively enhancing the capability to ensure water quality safety. Over the decade, the role of the South-to-North Water Transfers Project has shifted from a supplementary to a primary one. The national requirements for water quality safety have continuously increased, presenting the project with new challenges and difficulties in ensuring water quality safety. Firstly, there is an urgent need to comprehensively upgrade the monitoring and control system for the aquatic ecological environment. The current aquatic ecological monitoring in the South-to-North Water Transfers Project is in its initial stage, and further optimization of monitoring indicators and frequencies is required. Additionally, the foundation for monitoring emerging pollutants such as endocrine disruptors, antibiotics, and microplastics, which are of national concern, is relatively weak. Secondly, the interlinkage mechanism for water quality protection requires immediate refinement and improvement. Engineering operation and management entities need to further refine the mechanisms for government-enterprise coordination and vertically integrated pollution prevention and control. Thirdly, the capacity for risk prevention and control of water pollution needs to be enhanced.The project still faces risks and hidden dangers to water quality safety, including hazardous chemical transport accidents at bridge crossings, external water entering the canal, internal discharge of groundwater, damage to pipelines crossing oil-contaminated areas, and navigation-related risks. Fourthly, the emergency response capability for sudden water pollution incidents requires strengthening and enhancement. Fifthly, there is an urgent need to coordinate and lead the development of a scientific and technological support system for water quality protection. Confronted with the new situation and requirements, the project operation and management organizations were required to further improve the water quality safety assurance system and enhance management effectiveness. This paper planned the water quality safety assurance work for the project in the new era, aiming to refine and enhance the high-quality water quality protection system. It specifically proposed the next steps in five areas: water quality monitoring, protection system, risk prevention and control, emergency response, and scientific and technological support. These steps included continuously improving the monitoring and control capabilities for water quality and aquatic ecology, promoting the construction of a coordinated mechanism for water quality safety assurance, strengthening the dynamic management of pollution risk sources along the route, enhancing emergency response capabilities, and maintaining scientific and technological support for water quality protection. The research findings provided effective support for ensuring the water quality safety of the South-to-North Water Transfers Project and subsequent projects, safeguarding the continuous flow of clear water to the north.
Abstract:
The industrial water recycling rate is an important index to reflect industrial water use efficiency, industrial water saving degree, and to evaluate industrial water recycling. To comprehensively comprehend the recycling situation, the calculation and analysis of the recycling rate of industrial water is helpful. It is of great significance to predict the potential of industrial water saving, improve the level of industrial water saving and promote the sustainable development of industry. Currently, the research on industrial water recycling rate mainly focuses on the calculation of enterprise water recycling rate and the utilization of industrial water recycling rate, but lacks the research on the calculation method of regional water recycling rate. The statistical survey currently analyzes the water use in our country has basically achieved the comprehensive coverage of self-provided water source industrial enterprises and improved the quality of industrial water data. Based on this, the calculation of industrial water recycling rate will be more reasonable and reliable. A calculation method of the recycling rate of regional industrial water was proposed based on the water use statistics survey in Henan Province. The industrial water consumption of various industries in each city was obtained by classifying and calculating the water consumption of different sources. The quantity of recycled water of different industries in each city was calculated according to the recycling rate of various industries using typical enterprises. Finally, the industrial water recycling rate of each city and Henan Province was calculated. The results were then analyzed from the aspects of industry level, spatial distribution, sensitivity and water-saving potential. K-means clustering method was used to analyze the spatial distribution characteristics of industrial water recycling rate in Henan Province. The influence of each industry on the industrial water recycling rate in Henan Province was studied by single factor sensitivity analysis. Industrial water-saving potential was predicted. Based on the data of 2022, the industrial water recycling rate of Henan Province was calculated and analyzed. The results showed that the recycling rate of industrial water was 94.15% in Henan Province, 82.89% to 96.76% in various cities, and 23.89% to 98.04% in different industries. The overall level of industrial water recycling in Henan Province was higher, while there were significant differences among the cities. The thermal power industry had the highest impact on the recycling rate of industrial water in Henan Province, meanwhile the level of textile, food and other industries were lower. And the water-saving potential of improving the recycling rate of industrial water was 797 million cubic meters, which was considerable. The calculation method is suitable for the calculation of regional water recycling rate. The level of regional water recycling rate is restricted by the local water structure and the level of industrial recycling rate. The higher the proportion of water used by industries with high recycling rate, the higher the level of regional water recycling rate. Among various industries, the textile and food industries are the focus of improving the industrial recycling rate, and the thermal power industry is the focus of improving the water recycling rate of Henan Province and various cities. The calculated results are consistent with the actual situation of Henan Province, and can provide reference for the Henan Province to strengthen industrial water-saving management and improve industrial water use efficiency.
The industrial water recycling rate is an important index to reflect industrial water use efficiency, industrial water saving degree, and to evaluate industrial water recycling. To comprehensively comprehend the recycling situation, the calculation and analysis of the recycling rate of industrial water is helpful. It is of great significance to predict the potential of industrial water saving, improve the level of industrial water saving and promote the sustainable development of industry. Currently, the research on industrial water recycling rate mainly focuses on the calculation of enterprise water recycling rate and the utilization of industrial water recycling rate, but lacks the research on the calculation method of regional water recycling rate. The statistical survey currently analyzes the water use in our country has basically achieved the comprehensive coverage of self-provided water source industrial enterprises and improved the quality of industrial water data. Based on this, the calculation of industrial water recycling rate will be more reasonable and reliable. A calculation method of the recycling rate of regional industrial water was proposed based on the water use statistics survey in Henan Province. The industrial water consumption of various industries in each city was obtained by classifying and calculating the water consumption of different sources. The quantity of recycled water of different industries in each city was calculated according to the recycling rate of various industries using typical enterprises. Finally, the industrial water recycling rate of each city and Henan Province was calculated. The results were then analyzed from the aspects of industry level, spatial distribution, sensitivity and water-saving potential. K-means clustering method was used to analyze the spatial distribution characteristics of industrial water recycling rate in Henan Province. The influence of each industry on the industrial water recycling rate in Henan Province was studied by single factor sensitivity analysis. Industrial water-saving potential was predicted. Based on the data of 2022, the industrial water recycling rate of Henan Province was calculated and analyzed. The results showed that the recycling rate of industrial water was 94.15% in Henan Province, 82.89% to 96.76% in various cities, and 23.89% to 98.04% in different industries. The overall level of industrial water recycling in Henan Province was higher, while there were significant differences among the cities. The thermal power industry had the highest impact on the recycling rate of industrial water in Henan Province, meanwhile the level of textile, food and other industries were lower. And the water-saving potential of improving the recycling rate of industrial water was 797 million cubic meters, which was considerable. The calculation method is suitable for the calculation of regional water recycling rate. The level of regional water recycling rate is restricted by the local water structure and the level of industrial recycling rate. The higher the proportion of water used by industries with high recycling rate, the higher the level of regional water recycling rate. Among various industries, the textile and food industries are the focus of improving the industrial recycling rate, and the thermal power industry is the focus of improving the water recycling rate of Henan Province and various cities. The calculated results are consistent with the actual situation of Henan Province, and can provide reference for the Henan Province to strengthen industrial water-saving management and improve industrial water use efficiency.
Abstract:
The northern slope of Tianshan Mountains is the economic center of gravity of Xinjiang and an important urban agglomeration in Northwest China. Water consumption on the northern slopes of the Tianshan Mountains has increased over the years with the development of society and the economy. However, the contradiction between supply and demand for water resources had been exacerbated by the low precipitation and high evaporation intensity in Northwest China. The uneven spatial and temporal distribution of water resources in this region and the serious overexploitation of groundwater severely limited the development of local economy and restricted the adjustment function of ecosystem. Therefore, it is urgent to carry out the sustainable research of water resources on the northern slope of Tianshan Mountains. Previous studies on water resources on the northern slope of Tianshan Mountains mostly adopted the index system evaluation method to evaluate the carrying capacity and safety level of water resources. In the past, there were more studies on the development and utilization of water resources, but fewer studies on the sustainable utilization of water resources, and the research time scale mostly stayed around 2015. In this study, grey water footprint method was adopted to select indicators from the two aspects of "quality" and "quantity" of water resources, comprehensively considered the impact of water quality and quantity on water resources sustainability, and extended the time scale to 2020. Therefore, based on the basic data such as GDP, total water resources, water supply, chemical oxygen demand and ammonia nitrogen emission, this study employed the grey water footprint methodology to conduct a thorough assessment of the sustainable utilization of water resources on the northern slope of Tianshan Mountains from 2006 to 2020, aiming to offer insights and guidance for the formulation of water resources planning in this region. The results indicate that there are spatial variations in the grey water footprint among cities located on the northern slope of Tianshan Mountains. The spatial distribution pattern is 14.75 billion to 2.222 billion m3 higher in the central region than in the east and west regions, and the temporal distribution trend is first rising and then decreasing. Among them, the region as a whole increased by 11.56% in 2016 compared with 2006, and decreased by 23.30% in 2020 compared with 2016. There are differences in the composition of grey water footprint in different cities, most cities are dominated by agricultural grey water footprint, Urumqi domestic grey water footprint also occupies a large proportion, and Shihezi industrial grey water footprint accounts for the largest proportion. The sustainable utilization status of water resources in the northern slope of Tianshan Mountains as a whole and some cities mostly improved from 2014 to 2016, and the sustainable utilization index of water resources increased steadily. However, the sustainable utilization index of water resources in Bozhou and Tacheng regions grew slowly. Consequently, the study area continues to confront significant pressures regarding water resources, necessitating enhancements in the sustainable utilization of these resources. The findings of this study can serve as a valuable reference for promoting high-quality water resources management on the northern slope of Tianshan Mountains.
The northern slope of Tianshan Mountains is the economic center of gravity of Xinjiang and an important urban agglomeration in Northwest China. Water consumption on the northern slopes of the Tianshan Mountains has increased over the years with the development of society and the economy. However, the contradiction between supply and demand for water resources had been exacerbated by the low precipitation and high evaporation intensity in Northwest China. The uneven spatial and temporal distribution of water resources in this region and the serious overexploitation of groundwater severely limited the development of local economy and restricted the adjustment function of ecosystem. Therefore, it is urgent to carry out the sustainable research of water resources on the northern slope of Tianshan Mountains. Previous studies on water resources on the northern slope of Tianshan Mountains mostly adopted the index system evaluation method to evaluate the carrying capacity and safety level of water resources. In the past, there were more studies on the development and utilization of water resources, but fewer studies on the sustainable utilization of water resources, and the research time scale mostly stayed around 2015. In this study, grey water footprint method was adopted to select indicators from the two aspects of "quality" and "quantity" of water resources, comprehensively considered the impact of water quality and quantity on water resources sustainability, and extended the time scale to 2020. Therefore, based on the basic data such as GDP, total water resources, water supply, chemical oxygen demand and ammonia nitrogen emission, this study employed the grey water footprint methodology to conduct a thorough assessment of the sustainable utilization of water resources on the northern slope of Tianshan Mountains from 2006 to 2020, aiming to offer insights and guidance for the formulation of water resources planning in this region. The results indicate that there are spatial variations in the grey water footprint among cities located on the northern slope of Tianshan Mountains. The spatial distribution pattern is 14.75 billion to 2.222 billion m3 higher in the central region than in the east and west regions, and the temporal distribution trend is first rising and then decreasing. Among them, the region as a whole increased by 11.56% in 2016 compared with 2006, and decreased by 23.30% in 2020 compared with 2016. There are differences in the composition of grey water footprint in different cities, most cities are dominated by agricultural grey water footprint, Urumqi domestic grey water footprint also occupies a large proportion, and Shihezi industrial grey water footprint accounts for the largest proportion. The sustainable utilization status of water resources in the northern slope of Tianshan Mountains as a whole and some cities mostly improved from 2014 to 2016, and the sustainable utilization index of water resources increased steadily. However, the sustainable utilization index of water resources in Bozhou and Tacheng regions grew slowly. Consequently, the study area continues to confront significant pressures regarding water resources, necessitating enhancements in the sustainable utilization of these resources. The findings of this study can serve as a valuable reference for promoting high-quality water resources management on the northern slope of Tianshan Mountains.
Abstract:
China is among one of the countries in the world with high degree of water stress due to its uneven distribution of water resources. Reasonable evaluation of water resources utilization efficiency is an important method to balance the relationship between supply and demand of water resources supply as well as economic development, and it is also one of the important tasks of water-saving management. Water use efficiency evaluation is an important means to analyze and compare the effectiveness, rationality and water saving effect of water resources utilization in regions and industries. A comprehensive and sub-industry water use efficiency spectrum fitting method was constructed based on the combination of geographic information, water use efficiency and economic development data. The spectrum curves of comprehensive water use efficiency and water use efficiency of agriculture, industry and life in China were drawn by taking 31 provinces, autonomous regions and municipalities in the mainland of China from 2010 to 2022 as an example. The spatial and temporal variation rules of water use efficiency in various regions and industries along with their differences were analyzed. The main driving factors of water use efficiency changes were identified by geographic detectors, and water-saving optimization suggestions were put forward according to the characteristics of water use differences in various regions. The results show that from the year 2010 to 2022, the comprehensive water use efficiency and benefit of 97.0% of the provinces showed a synergistic growth trend, and the fitting degree of water use efficiency and economic benefit of different industries gradually improved with time with the simultaneous increased benefits of all the provinces. The increase of agricultural water use efficiency in Northeast China is the largest. The average annual decrease of water consumption per mu of actual irrigation of agricultural cultivated land is 1.9%, but the average annual increase of GDP per capita in the same period is only 46.6% of the national average. The comprehensive economic growth in the western region is the largest, with an average annual growth rate of 16.5%. The industrial water use efficiency also showed largest increase in the same period. The industrial added value water consumption in the western region has decreased by an average annual rate of 6.3% in the past 13 years. However, there is still a big gap between the agricultural water use efficiency and the eastern and central regions. The efficiency of industrial water use in the central region is low. The comprehensive water use efficiency and benefit in the eastern region continue to lead. The main driving factors for the change of agricultural water use efficiency in China are annual precipitation and water-saving irrigation area. The efficiency of industrial and domestic water use is most driven by water-saving investment. The comprehensive and industrial water usage in each region of China is expected to continue developing towards greater efficiency and higher benefits. The level of coordinated development will gradually increase, with agricultural and domestic water consumption showing a positive correlation with benefits. In the eastern region, water use efficiency and benefits are leading, although domestic water consumption remains high. In the western region, both water use efficiency and benefits are rising rapidly, yet agricultural water consumption is still significant, along with industrial water consumption in the central region. Based on the above analysis, the optimization suggestions for further tapping the water-saving potential and improving the water use efficiency are put forward according to the characteristics of each region, which provided a technical method for the economical and efficient utilization of water resources.
China is among one of the countries in the world with high degree of water stress due to its uneven distribution of water resources. Reasonable evaluation of water resources utilization efficiency is an important method to balance the relationship between supply and demand of water resources supply as well as economic development, and it is also one of the important tasks of water-saving management. Water use efficiency evaluation is an important means to analyze and compare the effectiveness, rationality and water saving effect of water resources utilization in regions and industries. A comprehensive and sub-industry water use efficiency spectrum fitting method was constructed based on the combination of geographic information, water use efficiency and economic development data. The spectrum curves of comprehensive water use efficiency and water use efficiency of agriculture, industry and life in China were drawn by taking 31 provinces, autonomous regions and municipalities in the mainland of China from 2010 to 2022 as an example. The spatial and temporal variation rules of water use efficiency in various regions and industries along with their differences were analyzed. The main driving factors of water use efficiency changes were identified by geographic detectors, and water-saving optimization suggestions were put forward according to the characteristics of water use differences in various regions. The results show that from the year 2010 to 2022, the comprehensive water use efficiency and benefit of 97.0% of the provinces showed a synergistic growth trend, and the fitting degree of water use efficiency and economic benefit of different industries gradually improved with time with the simultaneous increased benefits of all the provinces. The increase of agricultural water use efficiency in Northeast China is the largest. The average annual decrease of water consumption per mu of actual irrigation of agricultural cultivated land is 1.9%, but the average annual increase of GDP per capita in the same period is only 46.6% of the national average. The comprehensive economic growth in the western region is the largest, with an average annual growth rate of 16.5%. The industrial water use efficiency also showed largest increase in the same period. The industrial added value water consumption in the western region has decreased by an average annual rate of 6.3% in the past 13 years. However, there is still a big gap between the agricultural water use efficiency and the eastern and central regions. The efficiency of industrial water use in the central region is low. The comprehensive water use efficiency and benefit in the eastern region continue to lead. The main driving factors for the change of agricultural water use efficiency in China are annual precipitation and water-saving irrigation area. The efficiency of industrial and domestic water use is most driven by water-saving investment. The comprehensive and industrial water usage in each region of China is expected to continue developing towards greater efficiency and higher benefits. The level of coordinated development will gradually increase, with agricultural and domestic water consumption showing a positive correlation with benefits. In the eastern region, water use efficiency and benefits are leading, although domestic water consumption remains high. In the western region, both water use efficiency and benefits are rising rapidly, yet agricultural water consumption is still significant, along with industrial water consumption in the central region. Based on the above analysis, the optimization suggestions for further tapping the water-saving potential and improving the water use efficiency are put forward according to the characteristics of each region, which provided a technical method for the economical and efficient utilization of water resources.
TANG Xiaoyu1, 2, LIU Tie1, 2, *, HUANG Yue1, 2, PAN Xiaohui1, LING Yunan1, 2, PENG Jiabin3, ZHANG Peng4, SHANG Yu4
Abstract:
The Yanqi basin, located in northwestern China is one of the most water-stressed regions with highly developed irrigated agriculture. Bosten Lake of the Yanqi basin is the largest inland freshwater lake in China, which is the tail end of the Kaidu River and the source of the Kongque River. The local government plans to build seven hydroelectric power stations in the Kaidu River basin to improve the utilization of its water resources, and three hydroelectric power stations have been built so far. The dam seriously interferes with the natural flow regime of the river and alters the discharged surface irrigation water, making it difficult to reconcile the conflict between the irrigation water needed for agriculture and the water stored in the dam for power generation. Therefore, the Kai-Kong River basin is a river-lake-reservoir connectivity basin. The local agricultural irrigation extracts large amounts of groundwater, resulting in a rapid decline in the water level. The Kongque River has been delivering ecological water to the lower Tarim River since 2000, causing a dramatic drop in the Bosten Lake level. Therefore, win-win strategies should be considered in the management of water, agriculture, and energy resources with the aim to balancing agricultural production, energy development, and ecological protection. To solve the problem of irrational allocation of water resources in the Kaidu River basin, based on the River, Lake, and Reservoir Connectivity Project. The multi-objective optimal allocation model of water resources is constructed to maximize the economic benefits of agriculture, as well as to maximize the benefits of reservoir power generation, along with minimizing the regional ecological pressure index, and the optimal ecological water level of Bosten Lake as the constraint. To improve the solution efficiency and accuracy of the optimization model, we used the reference-point many-objective algorithm to solve the model. The optimization model is solved to produce multiple sets of optimization scenarios, causing decision interference for the manager. To help managers choose the most appropriate decision-making scheme, we constructed an evaluation index system for the most appropriate regional water resources allocation scheme based on the criterion layers of economic, social, and ecological benefits, and used the hierarchical analysis process to evaluate and analyze it. The option 34 is optimized for the most appropriate and local development after weighing economic, social, and ecological benefits. Option 34 would sacrifice some economic benefits to improve ecological benefits, with reservoir power generation reaching 3.99×108 kW?h and regional agricultural economic benefits reaching 2.166 billion yuan, while the ecological stress index is the smallest of the optimized options at 2.84. The optimization reduced the area planted with wheat, cotton, and pepper, and increased the area planted with corn and tomatoes. The largest reduction in the area under wheat was 3 312 hm2, followed by cotton at 795 hm2, and the smallest reduction in the area under pepper at 320 hm2. By reformulating the Bolangsumu diversion station Bosten Lake diversion ratio, there is a clear trend of increase in the water level of the big and small lakes, and the ecological water level of the lakes is guaranteed. This option increases reservoir power generation by 5.83%, reduces agricultural economic benefits by 2.34% while at the same time increases the ecological stress index by 40.08% compared to the traditional option. The optimized local cropping structure needs to be adjusted appropriately, with an increase in corn and tomato area and a decrease in wheat, cotton, and paper area. By improving the allocation of water into and out of Lake Bosten, the water level of both the large and small lakes has reached the optimum ecological level. The research results can provide a decision-making reference for local managers to formulate water resource allocation programs, which is of important theoretical significance and application value.
The Yanqi basin, located in northwestern China is one of the most water-stressed regions with highly developed irrigated agriculture. Bosten Lake of the Yanqi basin is the largest inland freshwater lake in China, which is the tail end of the Kaidu River and the source of the Kongque River. The local government plans to build seven hydroelectric power stations in the Kaidu River basin to improve the utilization of its water resources, and three hydroelectric power stations have been built so far. The dam seriously interferes with the natural flow regime of the river and alters the discharged surface irrigation water, making it difficult to reconcile the conflict between the irrigation water needed for agriculture and the water stored in the dam for power generation. Therefore, the Kai-Kong River basin is a river-lake-reservoir connectivity basin. The local agricultural irrigation extracts large amounts of groundwater, resulting in a rapid decline in the water level. The Kongque River has been delivering ecological water to the lower Tarim River since 2000, causing a dramatic drop in the Bosten Lake level. Therefore, win-win strategies should be considered in the management of water, agriculture, and energy resources with the aim to balancing agricultural production, energy development, and ecological protection. To solve the problem of irrational allocation of water resources in the Kaidu River basin, based on the River, Lake, and Reservoir Connectivity Project. The multi-objective optimal allocation model of water resources is constructed to maximize the economic benefits of agriculture, as well as to maximize the benefits of reservoir power generation, along with minimizing the regional ecological pressure index, and the optimal ecological water level of Bosten Lake as the constraint. To improve the solution efficiency and accuracy of the optimization model, we used the reference-point many-objective algorithm to solve the model. The optimization model is solved to produce multiple sets of optimization scenarios, causing decision interference for the manager. To help managers choose the most appropriate decision-making scheme, we constructed an evaluation index system for the most appropriate regional water resources allocation scheme based on the criterion layers of economic, social, and ecological benefits, and used the hierarchical analysis process to evaluate and analyze it. The option 34 is optimized for the most appropriate and local development after weighing economic, social, and ecological benefits. Option 34 would sacrifice some economic benefits to improve ecological benefits, with reservoir power generation reaching 3.99×108 kW?h and regional agricultural economic benefits reaching 2.166 billion yuan, while the ecological stress index is the smallest of the optimized options at 2.84. The optimization reduced the area planted with wheat, cotton, and pepper, and increased the area planted with corn and tomatoes. The largest reduction in the area under wheat was 3 312 hm2, followed by cotton at 795 hm2, and the smallest reduction in the area under pepper at 320 hm2. By reformulating the Bolangsumu diversion station Bosten Lake diversion ratio, there is a clear trend of increase in the water level of the big and small lakes, and the ecological water level of the lakes is guaranteed. This option increases reservoir power generation by 5.83%, reduces agricultural economic benefits by 2.34% while at the same time increases the ecological stress index by 40.08% compared to the traditional option. The optimized local cropping structure needs to be adjusted appropriately, with an increase in corn and tomato area and a decrease in wheat, cotton, and paper area. By improving the allocation of water into and out of Lake Bosten, the water level of both the large and small lakes has reached the optimum ecological level. The research results can provide a decision-making reference for local managers to formulate water resource allocation programs, which is of important theoretical significance and application value.
Abstract:
Evaluating the vulnerability of water resources is crucial for optimizing resource allocation and effectively managing water security risks. The Sixth Assessment Report published by the Intergovernmental Panel on Climate Change of United Nations in 2023 underscored that human-induced global warming is intensifying, leading to a greater occurrence of extreme droughts and floods. This phenomenon is contributing to heightened uncertainty and risks related to water supply and management. Yuxi City, located in central Yunnan, is a typical region subject to seasonal water shortages, with uneven spatial and temporal distribution of water resources. The conflict between the water supply and demand is further aggravated under the influence of the monsoon season. Assessing regional water resource vulnerability and uncovering the extent and spatial characteristics of the impacts of climate change and human activities on the water resource system can provide reliable guides for government water resource management, facilitating the sustainable development of water resources. Existing water resource vulnerability assessments primarily focused on specific regions, lacking generalizability and scalability across different spatial scales. To deal with these issues, the paper expanded the concept and connotation of water resource vulnerability. It addressed the deficiencies present in the spatial differentiation capability of current evaluation methods and the inability to adapt to varying spatial scales. A spatially independent evaluation index system was developed based on sensitivity pressure, water resource endowment status, and adaptive response. Eleven indicators were selected and employed, along with the combination of the Analytic Hierarchy Process and entropy weighting method to determine the weights of these indicators. By leveraging grid-based methodology and GIS spatial computing capabilities, these factors were integrated into a unified spatial framework. A grid-based vulnerability assessment of water resources was achieved through linear weighting of each grid cell, and the results were classified into five categories: non-vulnerable, weakly vulnerable, moderately vulnerable, highly vulnerable, and extremely vulnerable. This approach enhanced the spatial differentiation capability of the vulnerability assessment and provided a new perspective for regional water resource vulnerability assessment. It also offered decision-making support for the rational allocation of water resources in water diversion projects and the planning and management of water resources in receiving areas. The proposed method was applied to the Yuxi water-receiving area of the Central Yunnan Water Diversion Project, leading to the following conclusions: (1) Spatially, significant differences in vulnerability intensity existed among regions, with the western region showing higher vulnerability than the eastern region, forming a distribution pattern that gradually decreased from Xingyun Lake toward the east; (2) Temporally, the intensity of water resource vulnerability exhibited marked seasonal variation, with higher vulnerability during the winter and spring seasons compared to the summer and autumn seasons. Vulnerability peaked in February and was lowest in August. Precipitation and vegetation cover, which are strongly influenced by climate, had significant seasonal variability, with respective weight values of 0.105 9 and 0.064 6, making notable contributions to the seasonal characteristics of the vulnerability results; (3) The Xingyun Lake basin and its surrounding areas showed significantly higher water resource vulnerability than other regions, fluctuating between high and extreme vulnerability throughout the year. The three indicators - water resource utilization rate, per capita water consumption, and hydraulic engineering density - contributed substantially to the vulnerability assessment results. In summary, a multitude of factors influenced the water resource vulnerability, and future measures should aim to reduce human interference and lower the risk of water resource vulnerability in the region. Under the dual pressures of global climate change and socio-economic development, the resilience of the water resource system to environmental changes remained weak, and water resource vulnerability in this context continued to face significant challenges.
Evaluating the vulnerability of water resources is crucial for optimizing resource allocation and effectively managing water security risks. The Sixth Assessment Report published by the Intergovernmental Panel on Climate Change of United Nations in 2023 underscored that human-induced global warming is intensifying, leading to a greater occurrence of extreme droughts and floods. This phenomenon is contributing to heightened uncertainty and risks related to water supply and management. Yuxi City, located in central Yunnan, is a typical region subject to seasonal water shortages, with uneven spatial and temporal distribution of water resources. The conflict between the water supply and demand is further aggravated under the influence of the monsoon season. Assessing regional water resource vulnerability and uncovering the extent and spatial characteristics of the impacts of climate change and human activities on the water resource system can provide reliable guides for government water resource management, facilitating the sustainable development of water resources. Existing water resource vulnerability assessments primarily focused on specific regions, lacking generalizability and scalability across different spatial scales. To deal with these issues, the paper expanded the concept and connotation of water resource vulnerability. It addressed the deficiencies present in the spatial differentiation capability of current evaluation methods and the inability to adapt to varying spatial scales. A spatially independent evaluation index system was developed based on sensitivity pressure, water resource endowment status, and adaptive response. Eleven indicators were selected and employed, along with the combination of the Analytic Hierarchy Process and entropy weighting method to determine the weights of these indicators. By leveraging grid-based methodology and GIS spatial computing capabilities, these factors were integrated into a unified spatial framework. A grid-based vulnerability assessment of water resources was achieved through linear weighting of each grid cell, and the results were classified into five categories: non-vulnerable, weakly vulnerable, moderately vulnerable, highly vulnerable, and extremely vulnerable. This approach enhanced the spatial differentiation capability of the vulnerability assessment and provided a new perspective for regional water resource vulnerability assessment. It also offered decision-making support for the rational allocation of water resources in water diversion projects and the planning and management of water resources in receiving areas. The proposed method was applied to the Yuxi water-receiving area of the Central Yunnan Water Diversion Project, leading to the following conclusions: (1) Spatially, significant differences in vulnerability intensity existed among regions, with the western region showing higher vulnerability than the eastern region, forming a distribution pattern that gradually decreased from Xingyun Lake toward the east; (2) Temporally, the intensity of water resource vulnerability exhibited marked seasonal variation, with higher vulnerability during the winter and spring seasons compared to the summer and autumn seasons. Vulnerability peaked in February and was lowest in August. Precipitation and vegetation cover, which are strongly influenced by climate, had significant seasonal variability, with respective weight values of 0.105 9 and 0.064 6, making notable contributions to the seasonal characteristics of the vulnerability results; (3) The Xingyun Lake basin and its surrounding areas showed significantly higher water resource vulnerability than other regions, fluctuating between high and extreme vulnerability throughout the year. The three indicators - water resource utilization rate, per capita water consumption, and hydraulic engineering density - contributed substantially to the vulnerability assessment results. In summary, a multitude of factors influenced the water resource vulnerability, and future measures should aim to reduce human interference and lower the risk of water resource vulnerability in the region. Under the dual pressures of global climate change and socio-economic development, the resilience of the water resource system to environmental changes remained weak, and water resource vulnerability in this context continued to face significant challenges.
Abstract:
A superposition coupling method (SCM) is proposed to achieve high-precision cross-dimensional simulation coupling of one-dimensional and two-dimensional lattice Boltzmann method (LBM) hydrodynamic model. Hydrodynamic simulation of shallow water systems in complex topographic regions often requires cross-dimensional modeling, which can introduce boundary approximation issues, particularly in scenarios such as river-lake junctions, floodplains, and estuary areas. To solve the shallow water equations (SWE) in cross-dimensional scenarios, the SCM involves creating an artificial overlapping zone at the boundary of the 1D and 2D LBM models, facilitating the exchange of hydrodynamic information between the two models. Within this overlapping zone, a zero-gradient boundary condition is applied to derive the necessary variables for coupling. The 1D-2D coupled model was validated against benchmark models for circular cavity jet flow and sharp curved channel flow, demonstrating comparable accuracy to the full 2D model. In shallow water flow numerical simulation, typically different dimensional models are employed based on the topography and topology of the flow, which are crucial factors influencing water body movement. 1D models are generally more efficient for simulating the movement characteristics of large river channels, while 2D models are more suitable for large bodies of water with extensive free surfaces, such as floodplains, lakes, or reservoirs, provided accurate topographic data is available. Consequently, 1D and 2D models are often coupled to leverage their respective advantages. The proposed 1D-2D LBM coupling method utilizes a superposition approach, where the two models share an overlapping zone at their boundary. This zone serves as a buffer for exchanging hydrodynamic information between the models. The zero-gradient boundary condition is applied within the overlapping zone to ensure mass and momentum conservation. The method was implemented by calculating the velocity and depth at the boundaries of the 1D and 2D models and using these values to update the particle distributions within the overlapping zone. This process was iterated until convergence was achieved. The proposed coupling model was evaluated in comparison to benchmark models for circular cavity jet flow and sharp curved channel flow. The results showed that the coupling model produced water depth and velocity profiles that were in good agreement with those of the full 2D model, with minimal differences. The root mean square errors (RMSE) for water depth and velocity were within acceptable ranges, indicating the accuracy and reliability of the coupling method. The superposition approach for coupling 1D and 2D LBM hydrodynamic models provides a robust and efficient solution for simulating shallow water flows in complex topographic regions. The method leverages the strengths of both 1D and 2D models, providing accurate and reliable results while maintaining computational efficiency. The successful application of this method expands the capabilities of LBM in hydrodynamic simulation and demonstrates its potential for solving other multi-dimensional coupling problems, such as 1D-3D coupling or solute transport coupling.
A superposition coupling method (SCM) is proposed to achieve high-precision cross-dimensional simulation coupling of one-dimensional and two-dimensional lattice Boltzmann method (LBM) hydrodynamic model. Hydrodynamic simulation of shallow water systems in complex topographic regions often requires cross-dimensional modeling, which can introduce boundary approximation issues, particularly in scenarios such as river-lake junctions, floodplains, and estuary areas. To solve the shallow water equations (SWE) in cross-dimensional scenarios, the SCM involves creating an artificial overlapping zone at the boundary of the 1D and 2D LBM models, facilitating the exchange of hydrodynamic information between the two models. Within this overlapping zone, a zero-gradient boundary condition is applied to derive the necessary variables for coupling. The 1D-2D coupled model was validated against benchmark models for circular cavity jet flow and sharp curved channel flow, demonstrating comparable accuracy to the full 2D model. In shallow water flow numerical simulation, typically different dimensional models are employed based on the topography and topology of the flow, which are crucial factors influencing water body movement. 1D models are generally more efficient for simulating the movement characteristics of large river channels, while 2D models are more suitable for large bodies of water with extensive free surfaces, such as floodplains, lakes, or reservoirs, provided accurate topographic data is available. Consequently, 1D and 2D models are often coupled to leverage their respective advantages. The proposed 1D-2D LBM coupling method utilizes a superposition approach, where the two models share an overlapping zone at their boundary. This zone serves as a buffer for exchanging hydrodynamic information between the models. The zero-gradient boundary condition is applied within the overlapping zone to ensure mass and momentum conservation. The method was implemented by calculating the velocity and depth at the boundaries of the 1D and 2D models and using these values to update the particle distributions within the overlapping zone. This process was iterated until convergence was achieved. The proposed coupling model was evaluated in comparison to benchmark models for circular cavity jet flow and sharp curved channel flow. The results showed that the coupling model produced water depth and velocity profiles that were in good agreement with those of the full 2D model, with minimal differences. The root mean square errors (RMSE) for water depth and velocity were within acceptable ranges, indicating the accuracy and reliability of the coupling method. The superposition approach for coupling 1D and 2D LBM hydrodynamic models provides a robust and efficient solution for simulating shallow water flows in complex topographic regions. The method leverages the strengths of both 1D and 2D models, providing accurate and reliable results while maintaining computational efficiency. The successful application of this method expands the capabilities of LBM in hydrodynamic simulation and demonstrates its potential for solving other multi-dimensional coupling problems, such as 1D-3D coupling or solute transport coupling.
Abstract:
Baseflow is an important recharge to river runoff and is critical for maintaining the health of river ecosystems as well as for watershed water resource regulation and management. However, baseflow is difficult to measure and tracer-based methods are time-consuming and expensive, so non-tracer methods are commonly used for estimation. Digital filtering is a commonly used non-tracer method for partitioning baseflow, and the computational process is simple and easy to implement. The applicability of the digital filter model in different basins varies depending on the flow characteristics of the basin, and the filter parameters are often difficult to determine directly. In the past, most scholars often used empirical parameters to separate baseflow using digital filter model, and seldom considered the seasonal dynamic change characteristics of the parameters, which made the results of baseflow separation in different watersheds have a large uncertainty. To improve the accuracy of baseflow separation, a digital filter baseflow separation method was proposed based on seasonal recession analysis.The Luanchuan basin of the Yi River was taken as a typical study area, and four digital filtering models were used for baseflow separation, including three single-parameter filtering models (Lyne-Hollick, Chapman and Chapman-Maxwell), and a two-parameter filtering model (Eckhardt). Based on the 47 measured sub-flood data and daily runoff data of the watershed from 1964 to1979 and 2001 to 2020, the recession coefficient (k) of the watershed in different seasons was calculated. To analyze the effects of considering seasonal variations of model parameters on baseflow separation results and to calculate baseflow indices for each season in the study watershed, three evaluation indexes, namely, Nash-Sutcliffe efficiency coefficient (ENS), Gray correlation coefficient (DGR), and mean relative error (EMR) were used to analyze the errors and evaluate the accuracy of baseflow results and to assess the applicability of the four filtering models. The results showed that there was little land use change in the watershed over the two study periods, and the increase in NDVI did not have a significant effect on the number of receding water systems in the watershed. The precipitation-runoff double cumulative curve shows that precipitation is still the dominant factor leading to changes in runoff. The seasonal variation of the receding coefficient k in the Luanchuan basin was obvious, and the receding rates were faster in summer and fall, with k about 20 to 35 h, and slower in fall and winter, with k about 90 to 100 h. Compared with using a single parameter throughout the year, using different filtering parameters in each season significantly reduces the base flow index, which is more in line with the base flow characteristics of the watershed; Taking the oblique straight line separation method as the evaluation standard, the error and accuracy of baseflow indices obtained from several digital filtering methods were evaluated, the baseflow indices calculated by single-parameter than two-parameter filtering methods were generally larger, and the results of baseflow separation were greatly affected by the parameters. Eckhardt two-parameter filtering method had the best fitting effect, and it was the best baseflow separation method in Luanchuan watershed, and the average proportion of groundwater runoff recharge in the basin is about 33%. The results of this research provide new ideas for improving the accuracy of the digital filtering model to separate baseflow.
Baseflow is an important recharge to river runoff and is critical for maintaining the health of river ecosystems as well as for watershed water resource regulation and management. However, baseflow is difficult to measure and tracer-based methods are time-consuming and expensive, so non-tracer methods are commonly used for estimation. Digital filtering is a commonly used non-tracer method for partitioning baseflow, and the computational process is simple and easy to implement. The applicability of the digital filter model in different basins varies depending on the flow characteristics of the basin, and the filter parameters are often difficult to determine directly. In the past, most scholars often used empirical parameters to separate baseflow using digital filter model, and seldom considered the seasonal dynamic change characteristics of the parameters, which made the results of baseflow separation in different watersheds have a large uncertainty. To improve the accuracy of baseflow separation, a digital filter baseflow separation method was proposed based on seasonal recession analysis.The Luanchuan basin of the Yi River was taken as a typical study area, and four digital filtering models were used for baseflow separation, including three single-parameter filtering models (Lyne-Hollick, Chapman and Chapman-Maxwell), and a two-parameter filtering model (Eckhardt). Based on the 47 measured sub-flood data and daily runoff data of the watershed from 1964 to1979 and 2001 to 2020, the recession coefficient (k) of the watershed in different seasons was calculated. To analyze the effects of considering seasonal variations of model parameters on baseflow separation results and to calculate baseflow indices for each season in the study watershed, three evaluation indexes, namely, Nash-Sutcliffe efficiency coefficient (ENS), Gray correlation coefficient (DGR), and mean relative error (EMR) were used to analyze the errors and evaluate the accuracy of baseflow results and to assess the applicability of the four filtering models. The results showed that there was little land use change in the watershed over the two study periods, and the increase in NDVI did not have a significant effect on the number of receding water systems in the watershed. The precipitation-runoff double cumulative curve shows that precipitation is still the dominant factor leading to changes in runoff. The seasonal variation of the receding coefficient k in the Luanchuan basin was obvious, and the receding rates were faster in summer and fall, with k about 20 to 35 h, and slower in fall and winter, with k about 90 to 100 h. Compared with using a single parameter throughout the year, using different filtering parameters in each season significantly reduces the base flow index, which is more in line with the base flow characteristics of the watershed; Taking the oblique straight line separation method as the evaluation standard, the error and accuracy of baseflow indices obtained from several digital filtering methods were evaluated, the baseflow indices calculated by single-parameter than two-parameter filtering methods were generally larger, and the results of baseflow separation were greatly affected by the parameters. Eckhardt two-parameter filtering method had the best fitting effect, and it was the best baseflow separation method in Luanchuan watershed, and the average proportion of groundwater runoff recharge in the basin is about 33%. The results of this research provide new ideas for improving the accuracy of the digital filtering model to separate baseflow.
Abstract:
The acceleration of urbanization has changed the characteristics of the original underlying surface, destroyed the previously stable water circulation system in nature, and intensified the probability of urban flood disaster. In recent years, the concept of sponge city construction is continuously being developed, and the concept of "blue, green and gray" infrastructure has been proposed, which possibly could reduce the risk of urban flooding. In the process of sponge city construction, the sponge transformation of building districts is an important content. However, the recent research at this stage focuses on a single green or gray facility layout, and few scholars have conducted research on the scientific allocation and layout optimization of gray-green combined sponge facilities on the scale of building districts. The current research on sponge infrastructure should align with the specific requirements of regional sponge city construction. Therefore, a building district in Yichang City was selected as the research area. The urban storm flood model combined with the optimization algorithm model, a multi-objective optimization was carried out to optimize the deployment ratio of sponge infrastructure, and the scheme with the highest score was compared with the current situation of the study area and the scheme with the maximum allowed deployment of sponge facilities. Compared with the study area planning scheme, the cost of the optimization scheme was increased by 20.46%, but the overflow control volume and runoff control rates were also increased by 28.30% and 25.82%, respectively. Compared with the largest gray-green sponge facility that can be deployed, the cost showed a reduction of 17.97%, while the overflow control volume and runoff control rate were reduced by 10.99% and 3.36%, respectively, and the bottom residents of the community were not flooded under the scenario of a long-lasting rainstorm once in 30 years. The optimization scheme proposed illustrate the economic and hydrological benefits. The research showed that: (1)When the scale of various grey and green sponge facilities was increased, the range of runoff and overflow reduction control moved gradually towards stability, this means that in the process of sponge city construction, the growth rate of sponge facilities for flood response control will gradually slow down with the increase of their investment scale (2) The optimized sponge construction scheme reveals economic and hydrological benefits, and can provide technical support for future sponge city constructions.
The acceleration of urbanization has changed the characteristics of the original underlying surface, destroyed the previously stable water circulation system in nature, and intensified the probability of urban flood disaster. In recent years, the concept of sponge city construction is continuously being developed, and the concept of "blue, green and gray" infrastructure has been proposed, which possibly could reduce the risk of urban flooding. In the process of sponge city construction, the sponge transformation of building districts is an important content. However, the recent research at this stage focuses on a single green or gray facility layout, and few scholars have conducted research on the scientific allocation and layout optimization of gray-green combined sponge facilities on the scale of building districts. The current research on sponge infrastructure should align with the specific requirements of regional sponge city construction. Therefore, a building district in Yichang City was selected as the research area. The urban storm flood model combined with the optimization algorithm model, a multi-objective optimization was carried out to optimize the deployment ratio of sponge infrastructure, and the scheme with the highest score was compared with the current situation of the study area and the scheme with the maximum allowed deployment of sponge facilities. Compared with the study area planning scheme, the cost of the optimization scheme was increased by 20.46%, but the overflow control volume and runoff control rates were also increased by 28.30% and 25.82%, respectively. Compared with the largest gray-green sponge facility that can be deployed, the cost showed a reduction of 17.97%, while the overflow control volume and runoff control rate were reduced by 10.99% and 3.36%, respectively, and the bottom residents of the community were not flooded under the scenario of a long-lasting rainstorm once in 30 years. The optimization scheme proposed illustrate the economic and hydrological benefits. The research showed that: (1)When the scale of various grey and green sponge facilities was increased, the range of runoff and overflow reduction control moved gradually towards stability, this means that in the process of sponge city construction, the growth rate of sponge facilities for flood response control will gradually slow down with the increase of their investment scale (2) The optimized sponge construction scheme reveals economic and hydrological benefits, and can provide technical support for future sponge city constructions.
Abstract:
Original design flood and the check flood for the Danjiangkou Reservoir are 79 000 m3/s and 118 000 m3/s respectively, which may be significantly overestimated. The overestimation of design floods would lead to a lower flood limited water level (FLWL) in the reservoir, a key parameter for balancing flood control and comprehensive utilization during the flood season. Simultaneously, the hydrological regime of the downstream Han River has changed significantly, and the original design floods for the Danjiangkou Reservoir cannot meet the new demands of efficient water resources utilization and eco-environment protection. Consequently, it is imperative to recheck the design floods and characteristic water levels of the Danjiangkou Reservoir to enhance the comprehensive utilization benefits under the condition of the flood prevention standards unchanged. The observed flood data series at the Danjiangkou Reservoir dam site was restored and extended to 2023, and the historical floods of the Han River basin were re-evaluated. The discontinuous data series consisted of seven historically investigated floods in the years of 1583, 1693, 1724, 1832, 1852, 1867, and 1921, along with 95 years of annual maximum peak discharge and flood volume series recorded from 1929 to 2023, while the 1935 observed large flood had been treated as an extraordinary flood event. The P-Ⅲ distribution and curve fitting method were selected for the frequency analysis, and the sample statistical parameters were initially estimated using the linear moment’s method, followed by adjustments using the sum of squared deviations criterion to finalize the P-Ⅲ distribution parameters. Five different schemes were proposed to recheck the design floods of the Danjiangkou Reservoir and described as follow: Scheme-1, Extend both the observed flow data series (1929-2023) and historical investigation period (1583-2023), while the historically investigated floods used were the same as in the original design; Scheme-2, Revaluate historical investigation period (1368-2023), while the others were the same as Scheme-1; Scheme-3, Treat the floods of 1583 and 1724 as indetermined historical floods, while the others were the same as Scheme-2; Scheme-4, Exclude the historically investigated floods of 1583 and 1724, while the others were the same as Scheme-2; Scheme-5, Extend and use the observed flood series data only (1921-2023), while remain the 1935 observed large flood being treated as an extraordinary flood event. Only the historically investigated 7-day flood volumes from the years 1583, 1832, 1852, 1867, and 1921 are available, while the other two, which lacked magnitudes, are treated as indetermined floods that only consider for their ranking order. The other set of discontinuous data series is similarl to the above five schemes mentioned above. Multiple approaches, including palaeoflood estimation in the Han River basin, empirical formulas for the largest floods on record globally, and International Commission on Large Dams (ICOLD), are used to calculate probable maximum floods. After comprehensively analyzing and verifying the results estimated through multiple approaches and schemes, it is concluded that the checked design floods for the Danjiangkou Reservoir are significantly smaller than the original design values; The 1 000-year design and 10 000-year check peak discharges at the Danjiangkou Reservoir dam site are 56 950 m3/s and 70 000 m3/s, which have decreased by 27.91% and 40.68%, respectively. The 1 000-year annual maximum 7-day flood volume has reduced 2.1 billion m3, while the construction of upper stream reservoirs increases 1.7 billion m3 flood prevention storage. Therefore, it is suggested that the FLWL during the summer flood season be raised to 163 m, which can effectively enhance the flood water utilization rate and reservoir refill rate, and maximize comprehensive benefits, and ensure the safety of flood control operations.
Original design flood and the check flood for the Danjiangkou Reservoir are 79 000 m3/s and 118 000 m3/s respectively, which may be significantly overestimated. The overestimation of design floods would lead to a lower flood limited water level (FLWL) in the reservoir, a key parameter for balancing flood control and comprehensive utilization during the flood season. Simultaneously, the hydrological regime of the downstream Han River has changed significantly, and the original design floods for the Danjiangkou Reservoir cannot meet the new demands of efficient water resources utilization and eco-environment protection. Consequently, it is imperative to recheck the design floods and characteristic water levels of the Danjiangkou Reservoir to enhance the comprehensive utilization benefits under the condition of the flood prevention standards unchanged. The observed flood data series at the Danjiangkou Reservoir dam site was restored and extended to 2023, and the historical floods of the Han River basin were re-evaluated. The discontinuous data series consisted of seven historically investigated floods in the years of 1583, 1693, 1724, 1832, 1852, 1867, and 1921, along with 95 years of annual maximum peak discharge and flood volume series recorded from 1929 to 2023, while the 1935 observed large flood had been treated as an extraordinary flood event. The P-Ⅲ distribution and curve fitting method were selected for the frequency analysis, and the sample statistical parameters were initially estimated using the linear moment’s method, followed by adjustments using the sum of squared deviations criterion to finalize the P-Ⅲ distribution parameters. Five different schemes were proposed to recheck the design floods of the Danjiangkou Reservoir and described as follow: Scheme-1, Extend both the observed flow data series (1929-2023) and historical investigation period (1583-2023), while the historically investigated floods used were the same as in the original design; Scheme-2, Revaluate historical investigation period (1368-2023), while the others were the same as Scheme-1; Scheme-3, Treat the floods of 1583 and 1724 as indetermined historical floods, while the others were the same as Scheme-2; Scheme-4, Exclude the historically investigated floods of 1583 and 1724, while the others were the same as Scheme-2; Scheme-5, Extend and use the observed flood series data only (1921-2023), while remain the 1935 observed large flood being treated as an extraordinary flood event. Only the historically investigated 7-day flood volumes from the years 1583, 1832, 1852, 1867, and 1921 are available, while the other two, which lacked magnitudes, are treated as indetermined floods that only consider for their ranking order. The other set of discontinuous data series is similarl to the above five schemes mentioned above. Multiple approaches, including palaeoflood estimation in the Han River basin, empirical formulas for the largest floods on record globally, and International Commission on Large Dams (ICOLD), are used to calculate probable maximum floods. After comprehensively analyzing and verifying the results estimated through multiple approaches and schemes, it is concluded that the checked design floods for the Danjiangkou Reservoir are significantly smaller than the original design values; The 1 000-year design and 10 000-year check peak discharges at the Danjiangkou Reservoir dam site are 56 950 m3/s and 70 000 m3/s, which have decreased by 27.91% and 40.68%, respectively. The 1 000-year annual maximum 7-day flood volume has reduced 2.1 billion m3, while the construction of upper stream reservoirs increases 1.7 billion m3 flood prevention storage. Therefore, it is suggested that the FLWL during the summer flood season be raised to 163 m, which can effectively enhance the flood water utilization rate and reservoir refill rate, and maximize comprehensive benefits, and ensure the safety of flood control operations.
Abstract:
The advent of a new power system has brought forth a multitude of demands, elevating the benchmarks for operational monitoring, collaborative control across upstream and downstream stations, and the deployment of intelligent technologies within the Dadu River basin's power stations. It is crucial that the safety and efficiency of these power stations are ensured by the transition to intelligent operation control. The core aspects of operation control in the Dadu River basin power stations was explored, analyzing the current development landscape and identifying challenges in watershed power station operation control. In direct response to these challenges, a holistic development strategy and an intelligent enhancement of the operation control system were proposed. The upgraded system was designed to incorporate a range of functionalities which station operation monitoring, load adjustment, water, wind, and solar energy storage control, remote operation, emergency dispatch, and data management was included. Based on a thorough analysis of needs and the integration of advanced technologies, the development of this intelligent operation control system successfully met the demands of modern power systems. Significant enhancements in the safety and reliability of operation control for the Dadu River power stations were achieved through the establishment of the smart operation control system capabilities in monitoring and adjusting loads, managing various forms of energy storage, and facilitating remote and emergency operations were crucial in improving the overall performance of these power stations. The integration of data management further streamlined operations, providing a robust framework for decision-making and oversight. The intelligent upgrade of the operation control system for the Dadu River basin power stations marked a critical step toward the intelligent development of watershed power stations. This system adeptly addressed not only the current challenges but also paved the way for future advancements in power station operations. By fully embracing automation, digitalization, and informatization, harnessing a constellation of technologies including cloud computing, big data, the Internet of Things, mobile internet, and artificial intelligence, the system demonstrated a immense potential of intelligent operation control in the new power system era.
The advent of a new power system has brought forth a multitude of demands, elevating the benchmarks for operational monitoring, collaborative control across upstream and downstream stations, and the deployment of intelligent technologies within the Dadu River basin's power stations. It is crucial that the safety and efficiency of these power stations are ensured by the transition to intelligent operation control. The core aspects of operation control in the Dadu River basin power stations was explored, analyzing the current development landscape and identifying challenges in watershed power station operation control. In direct response to these challenges, a holistic development strategy and an intelligent enhancement of the operation control system were proposed. The upgraded system was designed to incorporate a range of functionalities which station operation monitoring, load adjustment, water, wind, and solar energy storage control, remote operation, emergency dispatch, and data management was included. Based on a thorough analysis of needs and the integration of advanced technologies, the development of this intelligent operation control system successfully met the demands of modern power systems. Significant enhancements in the safety and reliability of operation control for the Dadu River power stations were achieved through the establishment of the smart operation control system capabilities in monitoring and adjusting loads, managing various forms of energy storage, and facilitating remote and emergency operations were crucial in improving the overall performance of these power stations. The integration of data management further streamlined operations, providing a robust framework for decision-making and oversight. The intelligent upgrade of the operation control system for the Dadu River basin power stations marked a critical step toward the intelligent development of watershed power stations. This system adeptly addressed not only the current challenges but also paved the way for future advancements in power station operations. By fully embracing automation, digitalization, and informatization, harnessing a constellation of technologies including cloud computing, big data, the Internet of Things, mobile internet, and artificial intelligence, the system demonstrated a immense potential of intelligent operation control in the new power system era.
Abstract:
The step pumping station system is a very complex system that consists of the pumping station, barrage and canal section facilities, for which accurate water level prediction is recommended for the safe operation of water transfer projects. Machine learning models are widely used for water level prediction because of their fast response and small overshoot as compared with the traditional hydrodynamic equations. However, the complicated input data and the difficulty of time series prediction directly limit and affect the prediction accuracy, and raises the question as how to accurately evaluate the influence of input data on the prediction results to be solve in water level prediction model. The establishment of machine learning model helps to accurately predict the water level in front of the pump, realize intelligent dispatching, improve the operation efficiency of the pumping station, and is of great significance to the construction of water network. Long Short-Term Memory (LSTM), as a special recurrent neural network structure, has both the nonlinear properties of neural networks, and memory and long-term dependence, which facilitates its processing of time series data. The Changgou pumping station to Denglou pumping station in the Nansi-Dongping Lake section of the South-to-North Water Transfer East Route is taken as the research object. A framework for analyzing the influence of test input data on prediction results is proposed to construct a real-time prediction model of water level in front of pumping station based on LSTM model, and the optimization of the data input set of the prediction model is realized through the sensitivity analysis of each input factor, while the prediction analysis of the water level in front of Denglou Pumping Station under different foresight periods is carried out based on the above data combination. Four input factors, namely water level in front of Changgou station, flow rate of Changgou pumping station, water level in front of Denglou station and flow rate of Denglou pumping station, were initially determined as model inputs by the correlation coefficient method. The water level prediction model in front of Denglou pump station with a foresight period of 2 h is taken as an example, and the combination of input factors is further analyzed, with a Mean Absolute Error of 0.017 3, Mean Squared Error of 0.001 1, Root Mean Square Error of 0.032 7, and Mean Absolute Percentage Error of 0.000 5. The inputs for the pre-pumping water level prediction model were ultimately established as the water level in front of Denglou station, the flow rate at Changgou pumping station, and the water level in front of Changgou station. Following this, the accuracy of the prediction model for foresight periods of 2 hours, 4 hours, and 6 hours were analyzed, along with an error assessment based on these results. The results show that the prediction model with a foresight period of 6 h has higher accuracy. For the data anomalies existing in the model, most of them are caused by the manual regulation process, after removing the anomalies, the overall error of the model was reduced, and the prediction model with a foresight period of 4 h had the highest accuracy. The LSTM neural network real-time model constructed can accurately predict the water level in front of Denglou pumping station, and it fits well with the measured value, with high prediction accuracy, with the absolute value of the relative water depth error of less than 0.02 m except in the case of the abnormal value. The input parameters are optimized through sensitivity analysis, and when the input parameters are optimal combinations, the four indexes of the model were less than 0.05, and the correlation coefficient and the coefficient of determination were greater than 0.95. The LSTM model can reduce the complexity of the combination of input factors and ensure the accuracy of prediction. In summary, the model prediction results have a high degree of fit with the measured values, and their errors are within a reasonable range, and the LSTM prediction model had a stable prediction effect, which can be used for real-time prediction of the water level in front of the station of the terrace pumping station system.
The step pumping station system is a very complex system that consists of the pumping station, barrage and canal section facilities, for which accurate water level prediction is recommended for the safe operation of water transfer projects. Machine learning models are widely used for water level prediction because of their fast response and small overshoot as compared with the traditional hydrodynamic equations. However, the complicated input data and the difficulty of time series prediction directly limit and affect the prediction accuracy, and raises the question as how to accurately evaluate the influence of input data on the prediction results to be solve in water level prediction model. The establishment of machine learning model helps to accurately predict the water level in front of the pump, realize intelligent dispatching, improve the operation efficiency of the pumping station, and is of great significance to the construction of water network. Long Short-Term Memory (LSTM), as a special recurrent neural network structure, has both the nonlinear properties of neural networks, and memory and long-term dependence, which facilitates its processing of time series data. The Changgou pumping station to Denglou pumping station in the Nansi-Dongping Lake section of the South-to-North Water Transfer East Route is taken as the research object. A framework for analyzing the influence of test input data on prediction results is proposed to construct a real-time prediction model of water level in front of pumping station based on LSTM model, and the optimization of the data input set of the prediction model is realized through the sensitivity analysis of each input factor, while the prediction analysis of the water level in front of Denglou Pumping Station under different foresight periods is carried out based on the above data combination. Four input factors, namely water level in front of Changgou station, flow rate of Changgou pumping station, water level in front of Denglou station and flow rate of Denglou pumping station, were initially determined as model inputs by the correlation coefficient method. The water level prediction model in front of Denglou pump station with a foresight period of 2 h is taken as an example, and the combination of input factors is further analyzed, with a Mean Absolute Error of 0.017 3, Mean Squared Error of 0.001 1, Root Mean Square Error of 0.032 7, and Mean Absolute Percentage Error of 0.000 5. The inputs for the pre-pumping water level prediction model were ultimately established as the water level in front of Denglou station, the flow rate at Changgou pumping station, and the water level in front of Changgou station. Following this, the accuracy of the prediction model for foresight periods of 2 hours, 4 hours, and 6 hours were analyzed, along with an error assessment based on these results. The results show that the prediction model with a foresight period of 6 h has higher accuracy. For the data anomalies existing in the model, most of them are caused by the manual regulation process, after removing the anomalies, the overall error of the model was reduced, and the prediction model with a foresight period of 4 h had the highest accuracy. The LSTM neural network real-time model constructed can accurately predict the water level in front of Denglou pumping station, and it fits well with the measured value, with high prediction accuracy, with the absolute value of the relative water depth error of less than 0.02 m except in the case of the abnormal value. The input parameters are optimized through sensitivity analysis, and when the input parameters are optimal combinations, the four indexes of the model were less than 0.05, and the correlation coefficient and the coefficient of determination were greater than 0.95. The LSTM model can reduce the complexity of the combination of input factors and ensure the accuracy of prediction. In summary, the model prediction results have a high degree of fit with the measured values, and their errors are within a reasonable range, and the LSTM prediction model had a stable prediction effect, which can be used for real-time prediction of the water level in front of the station of the terrace pumping station system.
Abstract:
Large low-head pumping stations are widely constructed in the Yangtze River Delta, situated along both rivers and lakes. These stations are an important part of China's pumping station project, operating under low head, with large flow capacities and a high degree of automation. Due to its long and changeable inlet and outlet channels, the key to reduce the hydraulic loss in their channels was to improve the operation efficiency of drainage pumping stations . At present, due to terrain and other reasons, many low-head drainage pumping stations behind levees set up long dike box culverts as self-discharging channels. When large low-head drainage pumping stations with long self-discharging channels operate under pumping conditions, part of the water flowing from the rear side of the horn into the horn will rotate at low speed in the self-discharging channel behind the inlet channel to form a return zone, which exacerbates the vortex band and affect the performance of the device. Chenying pumping station was took as the research object to explore the improvement measures for the performance of the vertical axial flow pump with a long self-draining channel, with the partition pier set in the self-draining channel and a comparative study on the model test was conducted. The actual operation of the device could be accurately analyzed and the design scheme suitable for the pumping station was optimized based on the results of the model test of the pump device. Combining the results of the comparison between the original scheme and the optimized scheme, the targeted rectification optimization scheme was provided for the pumping station. The results indicated that the efficiency increased slightly in the full head range of the device after setting the partition pier and the device efficiency increased from 71.9% to 73.0% under the design head condition when the critical cavitation margin decreased from 8.7 m to 8.2 m. The addition of partition pier had little influence on the runaway performance of the device at various angles and the runaway speed corresponding to the maximum head of the device was 518.53 r/min, which was equal to 1.73 times of the rated speed, meeting the requirements of safe operation of the pump. The amplitude value of pressure pulsation of the horn inlet at different angles became smaller and more stable under large flow condition, and the amplitude value and average peak value of real-time water pressure pulsation also showed a decrease when the device operated under the design angle condition. Additionally, the amplitude of pressure pulsation and the D-value between the extreme amplitude of pressure pulsation at the horn inlet of the device in the large flow range of 364 to 426 L/s gradually decreased after the addition of partition pier. When the device operated under the design angle condition, both the high and low frequency signals on the spectrum of the corresponding two monitoring points were significantly reduced and the main frequency became multiples of the blade frequency, with the amplitude of various sub-harmonic frequencies decreased. The results showed that in a large low-head pumping station with an extended self-draining channel, adding a partition pier could eliminate the vortex zone. This change allowed water near the horn to flow into it more smoothly, resulting in a more stable flow field in the inlet channel. The addition of the partition pier significantly improved the energy, cavitation and pressure pulsation characteristics of the device, particularly enhancing its cavitation performance under low head and high flow conditions.
Large low-head pumping stations are widely constructed in the Yangtze River Delta, situated along both rivers and lakes. These stations are an important part of China's pumping station project, operating under low head, with large flow capacities and a high degree of automation. Due to its long and changeable inlet and outlet channels, the key to reduce the hydraulic loss in their channels was to improve the operation efficiency of drainage pumping stations . At present, due to terrain and other reasons, many low-head drainage pumping stations behind levees set up long dike box culverts as self-discharging channels. When large low-head drainage pumping stations with long self-discharging channels operate under pumping conditions, part of the water flowing from the rear side of the horn into the horn will rotate at low speed in the self-discharging channel behind the inlet channel to form a return zone, which exacerbates the vortex band and affect the performance of the device. Chenying pumping station was took as the research object to explore the improvement measures for the performance of the vertical axial flow pump with a long self-draining channel, with the partition pier set in the self-draining channel and a comparative study on the model test was conducted. The actual operation of the device could be accurately analyzed and the design scheme suitable for the pumping station was optimized based on the results of the model test of the pump device. Combining the results of the comparison between the original scheme and the optimized scheme, the targeted rectification optimization scheme was provided for the pumping station. The results indicated that the efficiency increased slightly in the full head range of the device after setting the partition pier and the device efficiency increased from 71.9% to 73.0% under the design head condition when the critical cavitation margin decreased from 8.7 m to 8.2 m. The addition of partition pier had little influence on the runaway performance of the device at various angles and the runaway speed corresponding to the maximum head of the device was 518.53 r/min, which was equal to 1.73 times of the rated speed, meeting the requirements of safe operation of the pump. The amplitude value of pressure pulsation of the horn inlet at different angles became smaller and more stable under large flow condition, and the amplitude value and average peak value of real-time water pressure pulsation also showed a decrease when the device operated under the design angle condition. Additionally, the amplitude of pressure pulsation and the D-value between the extreme amplitude of pressure pulsation at the horn inlet of the device in the large flow range of 364 to 426 L/s gradually decreased after the addition of partition pier. When the device operated under the design angle condition, both the high and low frequency signals on the spectrum of the corresponding two monitoring points were significantly reduced and the main frequency became multiples of the blade frequency, with the amplitude of various sub-harmonic frequencies decreased. The results showed that in a large low-head pumping station with an extended self-draining channel, adding a partition pier could eliminate the vortex zone. This change allowed water near the horn to flow into it more smoothly, resulting in a more stable flow field in the inlet channel. The addition of the partition pier significantly improved the energy, cavitation and pressure pulsation characteristics of the device, particularly enhancing its cavitation performance under low head and high flow conditions.
Abstract:
Radial gates are important water retaining and discharging structures in hydraulic engineering. Although radial gates are manufactured to have sufficient stiffness for the design water pressure, large vibrations can be produced due to water pressure fluctuation during discharge causing damage to the gate, especially when the dominant frequency of water pressure fluctuation approaches the natural frequency of the gate, which may cause resonance phenomenon. The fluctuating pressure of water flow under local opening on the radial gate panel is a frequent cause of gate vibration. In the past few decades, the hydraulic characteristics such as average pressure distribution, discharge capacity and flow field around the radial gate have been widely studied through numerical simulation, but the fluctuating pressure acted on the panel of the radial gate has not been solved yet. In order to calculate the fluctuating water pressure, a numerical model of 3D turbulent flow field around radial gate was established using two-equation turbulent model and volume of fluid method for free surface. Two consecutive runs of a steady-state run and a time-dependent transient run were carried out in order to determine the flow velocity at the inlet. Two turbulence models (i.e., k-ε turbulence model and k-ω turbulence model) were applied in the current study, and the accuracy of the k-ε and k-ω turbulence models for the simulation of fluctuating pressure was evaluated and discussed. Based on the k-ω turbulence model, the impact of downstream water level changes on the flow field and fluctuating pressure were investigated. The generation of fluctuating pressure showed close relation to the flow in the boundary layer near the radial gate panel. Reasonable selection of turbulence models and models with near-wall modifications is extremely important for the accuracy of calculating fluctuating pressure results. The combination of k-ε turbulence model and wall function was unable to capture the pressure fluctuating behavior on the gate panel, while the k-ω turbulence model combined with integration method can not only model the flow field around the gate, but also accurately calculate the fluctuating pressure, because of its better performance in the case of boundary-layer flows with a strong adverse pressure gradient. At the stable discharge stage, a large vortex was formed in front of the gate, was the main cause of the fluctuation of water pressure on the gate panel. The amplitude of water pressure fluctuations was influenced by the outflow form of the gate hole and the water level difference between upstream and downstream. Under submerged outflow conditions, a larger water level difference resulted in a higher root mean square value of fluctuating pressure. Conversely, under free outflow conditions, a larger water level difference led to a lower root mean square value of fluctuating pressure. The dominant frequency of fluctuating pressure at each point on the panel under the same operating conditions was identical and was mainly dependent on the orifice flow pattern of the sluice, but independent of the water level difference between upstream and downstream. Under submerged outflow conditions, a large counterclockwise vortex was formed behind the gate, but under free outflow conditions, no obvious vortex will form behind the gate. The dominant frequency of pressure fluctuation under free outflow conditions was higher than that under submerged outflow conditions.
Radial gates are important water retaining and discharging structures in hydraulic engineering. Although radial gates are manufactured to have sufficient stiffness for the design water pressure, large vibrations can be produced due to water pressure fluctuation during discharge causing damage to the gate, especially when the dominant frequency of water pressure fluctuation approaches the natural frequency of the gate, which may cause resonance phenomenon. The fluctuating pressure of water flow under local opening on the radial gate panel is a frequent cause of gate vibration. In the past few decades, the hydraulic characteristics such as average pressure distribution, discharge capacity and flow field around the radial gate have been widely studied through numerical simulation, but the fluctuating pressure acted on the panel of the radial gate has not been solved yet. In order to calculate the fluctuating water pressure, a numerical model of 3D turbulent flow field around radial gate was established using two-equation turbulent model and volume of fluid method for free surface. Two consecutive runs of a steady-state run and a time-dependent transient run were carried out in order to determine the flow velocity at the inlet. Two turbulence models (i.e., k-ε turbulence model and k-ω turbulence model) were applied in the current study, and the accuracy of the k-ε and k-ω turbulence models for the simulation of fluctuating pressure was evaluated and discussed. Based on the k-ω turbulence model, the impact of downstream water level changes on the flow field and fluctuating pressure were investigated. The generation of fluctuating pressure showed close relation to the flow in the boundary layer near the radial gate panel. Reasonable selection of turbulence models and models with near-wall modifications is extremely important for the accuracy of calculating fluctuating pressure results. The combination of k-ε turbulence model and wall function was unable to capture the pressure fluctuating behavior on the gate panel, while the k-ω turbulence model combined with integration method can not only model the flow field around the gate, but also accurately calculate the fluctuating pressure, because of its better performance in the case of boundary-layer flows with a strong adverse pressure gradient. At the stable discharge stage, a large vortex was formed in front of the gate, was the main cause of the fluctuation of water pressure on the gate panel. The amplitude of water pressure fluctuations was influenced by the outflow form of the gate hole and the water level difference between upstream and downstream. Under submerged outflow conditions, a larger water level difference resulted in a higher root mean square value of fluctuating pressure. Conversely, under free outflow conditions, a larger water level difference led to a lower root mean square value of fluctuating pressure. The dominant frequency of fluctuating pressure at each point on the panel under the same operating conditions was identical and was mainly dependent on the orifice flow pattern of the sluice, but independent of the water level difference between upstream and downstream. Under submerged outflow conditions, a large counterclockwise vortex was formed behind the gate, but under free outflow conditions, no obvious vortex will form behind the gate. The dominant frequency of pressure fluctuation under free outflow conditions was higher than that under submerged outflow conditions.
Abstract:
The safe and efficient operation of the pumping station relies on a thorough understanding of its standard operating characteristics and the internal flow mechanisms during abnormal conditions, especially under negative head. Ignoring this issue can result in serious consequences, such as decreased pump efficiency, a higher risk of mechanical failure, and potential hazards to the surrounding environment. Unfortunately, there are limited researches, both domestically and internationally, on this topic, highlighting the need for further studies. To investigate a specific bi-directional flow channel pump station model, a combination of simulations and experimental data was employed. Unsteady flow field and fluid-structure interaction simulations were conducted using the SST k-ω turbulence model to accurately capture the behavior of bi-directional channel pump devices. After testing the performance of the zero-adjusted pump under normal working conditions, this paper selects the operating characteristics of the bi-directional axial flow pump device when blade setting angle is 0° as the main research object to test under negative head conditions. The numerical results for hydraulic characteristics were then referenced with experimental data to ensure precision and to validate the accuracy of the simulation. The findings show that under negative head, the impeller acts as a braking device for pumping device due to changes in pressure distribution on blade surface and velocity distribution inside impeller. The number of blades is identified as a key factor determining the distribution of vortices at the junction of impeller blade and guide vane, influencing efficiency and stability of pump. The velocity distribution within the impeller is in accordance with the pressure distribution on the blade surface. Flow separation at the blade tip results in nearly symmetrical flow velocities on both surfaces and a relatively uniform overall flow velocity within the impeller. The number of blades is identified as a pivotal factor determining vortex distribution at the interface, significantly influencing pump efficiency and stability. Furthermore, an in-depth analysis revealed that under normal working conditions, the axial force of the pump is positive. However, under negative head conditions, with increasing flow, the axial force gradually decreases or even becomes negative. When this occurs, it poses an increased risk of damage to thrust tile, rotor and other equipment in the pump unit. Maximum deformation occurs at the angle between leading edge of the blade and rim indicating that this area is more susceptible to stress and deformation under negative head conditions. As the flow rate rises, both the peak equivalent stress and the maximum deformation of the impeller diminish. To summarize, initial but valuable insights were provided into operating characteristics, internal flow mechanisms, and structural dynamic characteristics of bi-directional flow channel axial pumps under negative head operating conditions. This has significant implications for optimizing pump design and ensuring safety management. By gaining a deeper understanding of complex interactions between fluid flow structure and pump components, engineers can develop more robust and efficient pumping station designs which could ultimately lead to overall improved performance and reduced maintenance costs.
The safe and efficient operation of the pumping station relies on a thorough understanding of its standard operating characteristics and the internal flow mechanisms during abnormal conditions, especially under negative head. Ignoring this issue can result in serious consequences, such as decreased pump efficiency, a higher risk of mechanical failure, and potential hazards to the surrounding environment. Unfortunately, there are limited researches, both domestically and internationally, on this topic, highlighting the need for further studies. To investigate a specific bi-directional flow channel pump station model, a combination of simulations and experimental data was employed. Unsteady flow field and fluid-structure interaction simulations were conducted using the SST k-ω turbulence model to accurately capture the behavior of bi-directional channel pump devices. After testing the performance of the zero-adjusted pump under normal working conditions, this paper selects the operating characteristics of the bi-directional axial flow pump device when blade setting angle is 0° as the main research object to test under negative head conditions. The numerical results for hydraulic characteristics were then referenced with experimental data to ensure precision and to validate the accuracy of the simulation. The findings show that under negative head, the impeller acts as a braking device for pumping device due to changes in pressure distribution on blade surface and velocity distribution inside impeller. The number of blades is identified as a key factor determining the distribution of vortices at the junction of impeller blade and guide vane, influencing efficiency and stability of pump. The velocity distribution within the impeller is in accordance with the pressure distribution on the blade surface. Flow separation at the blade tip results in nearly symmetrical flow velocities on both surfaces and a relatively uniform overall flow velocity within the impeller. The number of blades is identified as a pivotal factor determining vortex distribution at the interface, significantly influencing pump efficiency and stability. Furthermore, an in-depth analysis revealed that under normal working conditions, the axial force of the pump is positive. However, under negative head conditions, with increasing flow, the axial force gradually decreases or even becomes negative. When this occurs, it poses an increased risk of damage to thrust tile, rotor and other equipment in the pump unit. Maximum deformation occurs at the angle between leading edge of the blade and rim indicating that this area is more susceptible to stress and deformation under negative head conditions. As the flow rate rises, both the peak equivalent stress and the maximum deformation of the impeller diminish. To summarize, initial but valuable insights were provided into operating characteristics, internal flow mechanisms, and structural dynamic characteristics of bi-directional flow channel axial pumps under negative head operating conditions. This has significant implications for optimizing pump design and ensuring safety management. By gaining a deeper understanding of complex interactions between fluid flow structure and pump components, engineers can develop more robust and efficient pumping station designs which could ultimately lead to overall improved performance and reduced maintenance costs.
Determining the relative density of deep sand in overburden layer based on standard penetration test
WANG Shaokun1, 2, YANG Zhengquan1, 2, *, LIU Xiaosheng1, 2, WEN Yanfeng1, 2, ZHU Kaibin1, 2, ZHAO Yiying1, 2, ZHAO Jianming1, 2
Abstract:
The relative density of sand characterizes its compactness in the soil layer and is an important indicator of its physical property. It has a significant impact on its mechanical properties and is a basic control condition for conducting mechanical property tests. Due to the unstable particle structure of the deep sand layer, the interference of conventional sampling methods may cause significant changes in macroscopic properties (including relative density) of sand. Meanwhile, special sampling methods, such as frozen sampling, are complex to operate and costly. For general engineering projects, the undisturbed sampling of deep-buried sand is difficult in practice. Therefore, a simple, efficient, and reasonable method for determining the relative density of deep-buried sand is a necessity. Internationally, the standard penetration test is a commonly used field test, and its test results can directly or indirectly represent various mechanical properties of the soil. It has been demonstrated that there is a correlation between the standard penetration blow count and the relative density of sand under certain overburden stress conditions. Based on relevant research results internationally, standard penetration test results of 5 typical sand were summarized by Skempton, and the correlation among standard penetration test blow count, relative density and effective overburden stress was formulated. Based on the recommended standard penetration test energy transfer rate (60%) proposed by Seed et al., the standard penetration test blow count was standardized as standard penetration test blow count with the same energy transfer rate by Skempton. Therefore, the above formula was standardized. Based on these relationships, a relative density estimate formula and the corresponding method for deep-buried sand in the overburden layer based on the results of standard penetration tests were established. Based on the moisture content and gradation of 5 typical sand summarized by Skempton, a sand relationship selection method was proposed for selecting the characteristic parameters of the empirical relationship between relative density, standard penetration blow count, and effective overburden stress. The effectiveness and stability of the established method for estimating the relative density of sand were demonstrated by the analysis of various engineering examples. A method was suggested to replace uncertain overburden sand density with estimated sand density, and the influence of this method on the results was analyzed through an example calculation. The analysis results indicate that replacing uncertain overburden sand density with this method has little impact on calculation results. It is recommended that an iterative calculation method may be used when high accuracy is required. Additionally, indoor tests should be conducted simulating field calibrations on the analyzed sand for projects with strict safety and accuracy requirements.
The relative density of sand characterizes its compactness in the soil layer and is an important indicator of its physical property. It has a significant impact on its mechanical properties and is a basic control condition for conducting mechanical property tests. Due to the unstable particle structure of the deep sand layer, the interference of conventional sampling methods may cause significant changes in macroscopic properties (including relative density) of sand. Meanwhile, special sampling methods, such as frozen sampling, are complex to operate and costly. For general engineering projects, the undisturbed sampling of deep-buried sand is difficult in practice. Therefore, a simple, efficient, and reasonable method for determining the relative density of deep-buried sand is a necessity. Internationally, the standard penetration test is a commonly used field test, and its test results can directly or indirectly represent various mechanical properties of the soil. It has been demonstrated that there is a correlation between the standard penetration blow count and the relative density of sand under certain overburden stress conditions. Based on relevant research results internationally, standard penetration test results of 5 typical sand were summarized by Skempton, and the correlation among standard penetration test blow count, relative density and effective overburden stress was formulated. Based on the recommended standard penetration test energy transfer rate (60%) proposed by Seed et al., the standard penetration test blow count was standardized as standard penetration test blow count with the same energy transfer rate by Skempton. Therefore, the above formula was standardized. Based on these relationships, a relative density estimate formula and the corresponding method for deep-buried sand in the overburden layer based on the results of standard penetration tests were established. Based on the moisture content and gradation of 5 typical sand summarized by Skempton, a sand relationship selection method was proposed for selecting the characteristic parameters of the empirical relationship between relative density, standard penetration blow count, and effective overburden stress. The effectiveness and stability of the established method for estimating the relative density of sand were demonstrated by the analysis of various engineering examples. A method was suggested to replace uncertain overburden sand density with estimated sand density, and the influence of this method on the results was analyzed through an example calculation. The analysis results indicate that replacing uncertain overburden sand density with this method has little impact on calculation results. It is recommended that an iterative calculation method may be used when high accuracy is required. Additionally, indoor tests should be conducted simulating field calibrations on the analyzed sand for projects with strict safety and accuracy requirements.
Abstract:
To address the issue of variations in normal water levels across different segments during the operational phase of the canal characterized by a gentle slope and curved trajectory, a smooth organic glass material was utilized to simulate the water surface line in model tests conducted on the canal. The experimental approach adopted a normal distribution model and was formulated on the basis of gravity similarity principles, employing a geometric scale ratio of 1:40. The outcomes of the experiment indicated a notable disparity between the water levels recorded in the flume model test and those calculated using the uniform flow formula. Specifically, the measured water level surpassed the calculated water level, prompting an investigation into the underlying causes of the elevated measured water level and the attainment of precise water level estimations within the spillway. This study employed a tripartite methodology encompassing model tests, theoretical analysis, and numerical simulations. The analysis of various factors influencing water levels in the aqueduct model test revealed several key aspects. Firstly, the curvature of the aqueduct impacted the flow pattern, resulting in elevated water levels. Secondly, discrepancies in roughness ratio scales were observed, with the model's roughness being excessive, leading to heightened head loss and subsequently increased water levels. Lastly, the discrepancy between the actual aqueduct section, which featured a reduced water area, and the rectangular section utilized in the uniform flow calculation formula contributed to the rise in water levels. Subsequent roughness determination tests were conducted on the smooth organic glass material utilized in the model test, and the obtained roughness data were scrutinized. A water level correction method was later devised based on the calibration test results and the uniform flow calculation formula to rectify situations where roughness ratio scales were contradictory, thereby correcting the measured water levels. Furthermore, a three-dimensional finite element numerical simulation study was conducted to analyze the water surface line of the flume. The accuracy of the numerical simulation was verified against the data obtained from the flume model test, affirming the efficacy of the proposed water level correction method for addressing dissimilar roughness ratio scales. The study revealed that the water level at the bend of the fishway was 8-10 centimeters higher than that of the straight section. As the distance from the bend increased, the water level gradually decreased until it aligned with the calculated water level, indicating that the bend no longer influenced the water level. Additionally, the water level of the aqueduct's cross section design was 4-6 centimeters higher than that of a rectangular cross section. The primary factor contributing to the substantial disparity between the measured water level in the aqueduct and the calculated water level for uniform flow was the dissimilarity in roughness ratio scales. The roughness coefficient was not merely indicative of wall surface roughness, but was also influenced by hydraulic factors and water flow characteristics. The surface roughness of the polished organic glass plate ranged from 0.007 9 to 0.008 3. The data indicated a decline in roughness as flow rate rises, and conversely, an increase in roughness with steeper slopes.
To address the issue of variations in normal water levels across different segments during the operational phase of the canal characterized by a gentle slope and curved trajectory, a smooth organic glass material was utilized to simulate the water surface line in model tests conducted on the canal. The experimental approach adopted a normal distribution model and was formulated on the basis of gravity similarity principles, employing a geometric scale ratio of 1:40. The outcomes of the experiment indicated a notable disparity between the water levels recorded in the flume model test and those calculated using the uniform flow formula. Specifically, the measured water level surpassed the calculated water level, prompting an investigation into the underlying causes of the elevated measured water level and the attainment of precise water level estimations within the spillway. This study employed a tripartite methodology encompassing model tests, theoretical analysis, and numerical simulations. The analysis of various factors influencing water levels in the aqueduct model test revealed several key aspects. Firstly, the curvature of the aqueduct impacted the flow pattern, resulting in elevated water levels. Secondly, discrepancies in roughness ratio scales were observed, with the model's roughness being excessive, leading to heightened head loss and subsequently increased water levels. Lastly, the discrepancy between the actual aqueduct section, which featured a reduced water area, and the rectangular section utilized in the uniform flow calculation formula contributed to the rise in water levels. Subsequent roughness determination tests were conducted on the smooth organic glass material utilized in the model test, and the obtained roughness data were scrutinized. A water level correction method was later devised based on the calibration test results and the uniform flow calculation formula to rectify situations where roughness ratio scales were contradictory, thereby correcting the measured water levels. Furthermore, a three-dimensional finite element numerical simulation study was conducted to analyze the water surface line of the flume. The accuracy of the numerical simulation was verified against the data obtained from the flume model test, affirming the efficacy of the proposed water level correction method for addressing dissimilar roughness ratio scales. The study revealed that the water level at the bend of the fishway was 8-10 centimeters higher than that of the straight section. As the distance from the bend increased, the water level gradually decreased until it aligned with the calculated water level, indicating that the bend no longer influenced the water level. Additionally, the water level of the aqueduct's cross section design was 4-6 centimeters higher than that of a rectangular cross section. The primary factor contributing to the substantial disparity between the measured water level in the aqueduct and the calculated water level for uniform flow was the dissimilarity in roughness ratio scales. The roughness coefficient was not merely indicative of wall surface roughness, but was also influenced by hydraulic factors and water flow characteristics. The surface roughness of the polished organic glass plate ranged from 0.007 9 to 0.008 3. The data indicated a decline in roughness as flow rate rises, and conversely, an increase in roughness with steeper slopes.
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Abstract:
The Middle Route of South to North Water Diversion Project (MRP) has long canals, involves many areas and hydraulic structures, transfers water by a huge amount, and has various working conditions. These all bring great difficulties to the regulation, control, and management of the project. The technical problem of the engineering lies in the fact that the scientific and mechanism problems behind it are not fully revealed and solved, including multi-dimensional equilibrium control mechanism of multiple water sources under changing conditions, multi-process coupling mechanism of water quantity and water quality, emergency scheduling model for multi-material water pollution, hydraulic response mechanism and control of open channel under multi-gate joint application. In order to establish a complete set of technical system to support its scheduling, this paper summarizes the existing research on the five key points of forecast, scheduling, simulation, control, and evaluation. And on the basis of summarizing the previous research, the key technologies awaiting urgent research are explained in detail, including forecast and scheduling in water source areas and water-receiving areas, multi-phase simulation of water pollution, water quality and water quality control, automatic control technology, evaluation technology, and platform construction. Finally, the paper discusses the scientific problems to be solved in order to realize the intelligent regulation and emergency regulation for the MRP and makes a summary of the research.
The Middle Route of South to North Water Diversion Project (MRP) has long canals, involves many areas and hydraulic structures, transfers water by a huge amount, and has various working conditions. These all bring great difficulties to the regulation, control, and management of the project. The technical problem of the engineering lies in the fact that the scientific and mechanism problems behind it are not fully revealed and solved, including multi-dimensional equilibrium control mechanism of multiple water sources under changing conditions, multi-process coupling mechanism of water quantity and water quality, emergency scheduling model for multi-material water pollution, hydraulic response mechanism and control of open channel under multi-gate joint application. In order to establish a complete set of technical system to support its scheduling, this paper summarizes the existing research on the five key points of forecast, scheduling, simulation, control, and evaluation. And on the basis of summarizing the previous research, the key technologies awaiting urgent research are explained in detail, including forecast and scheduling in water source areas and water-receiving areas, multi-phase simulation of water pollution, water quality and water quality control, automatic control technology, evaluation technology, and platform construction. Finally, the paper discusses the scientific problems to be solved in order to realize the intelligent regulation and emergency regulation for the MRP and makes a summary of the research.
Abstract:
Sensitivity analysis was performed to analyze the inputs and outputs of the complex model and system qualitatively and quantitatively, which can benefit the inspection of model structure, identification of model parameters, and model application. In this paper, Sobol method was applied to evaluate the sensitivity of single parameter and multiple parameters of the model in the Huanren reservoir catchment. The objective functions of sensitivity analysis included the deterministic coefficients and error coefficients of total water, low flow, and high flow. The results showed that the sensitivity of parameters was different under different objective functions, and Sobol method can provide the sensitivity for all parameters and sensitivity between each parameter, which is useful for sensitivity analysis of hydrological models.
Sensitivity analysis was performed to analyze the inputs and outputs of the complex model and system qualitatively and quantitatively, which can benefit the inspection of model structure, identification of model parameters, and model application. In this paper, Sobol method was applied to evaluate the sensitivity of single parameter and multiple parameters of the model in the Huanren reservoir catchment. The objective functions of sensitivity analysis included the deterministic coefficients and error coefficients of total water, low flow, and high flow. The results showed that the sensitivity of parameters was different under different objective functions, and Sobol method can provide the sensitivity for all parameters and sensitivity between each parameter, which is useful for sensitivity analysis of hydrological models.
Abstract:
Using precipitation and temperature for the period of 1851-2008 of Xi'an city, the paper analyzed the variation trends and abrupt changes of hydro-meteorological factors including precipitation and temperature using linear fitting, sliding t test, ordered clustering and Mann-Kendall methods．Firstly, the variation trends of precipitation and temperature were analyzed using linear fitting and anomaly percentage, and then the change characteristic of number of rainy days and precipitation were further analyzed. Finally, the paper investigated the abrupt changes of precipitation and temperature using sliding t test, ordered clustering and Mann-Kendall methods. The results showed that the precipitation decreased gradually. Precipitation accounts for 58% of annual precipitation during the flood season and the annual precipitation distribution is uneven. The annual mean temperature and extreme minimum temperature have increased. The abrupt changes of the precipitation were detected in 1958、1975 and 1980, and the abrupt changes of annual average temperature have found between 1993-1995.
Using precipitation and temperature for the period of 1851-2008 of Xi'an city, the paper analyzed the variation trends and abrupt changes of hydro-meteorological factors including precipitation and temperature using linear fitting, sliding t test, ordered clustering and Mann-Kendall methods．Firstly, the variation trends of precipitation and temperature were analyzed using linear fitting and anomaly percentage, and then the change characteristic of number of rainy days and precipitation were further analyzed. Finally, the paper investigated the abrupt changes of precipitation and temperature using sliding t test, ordered clustering and Mann-Kendall methods. The results showed that the precipitation decreased gradually. Precipitation accounts for 58% of annual precipitation during the flood season and the annual precipitation distribution is uneven. The annual mean temperature and extreme minimum temperature have increased. The abrupt changes of the precipitation were detected in 1958、1975 and 1980, and the abrupt changes of annual average temperature have found between 1993-1995.
Abstract:
Based on the T OE theor et ical fr amewo rk ( T echnolo gy2 Or ganizatio n2Environment) and the specific situation of smart water co nstr uction, the TOE framew ork w hich affects smart water constructio n was developed, and the effect s of each impact facto r o n the construction and development o f smar t w ater wer e analyzed from the technical, o rg anizat ional, and env iro nmental dimensions. T he technical dimensio n factors include the technica l superio rity, complex it y, compatibility , and o bser vability. T he org anizational dimension factor s include the const ruction necessity, demand urg ency , and co nstr uction feasibility . The envir on2 mental dimension factor s include the support sy st em, standard system, and info rmation securit y. On the basis, analyt ic hierarchy pr ocess ( AH P) w as used to determine the pr ior ity of the impact facto rs. The results showed that the or ganizatio nal dimensio n facto rs and technical dimension fact ors have hig h impacts on smart water construction w ith the weig ht o f 49% and 31% o ver the index system respect ively. Amo ng the impact factor s, const ruct ion necessity has the hig hest weig ht ( 25%) , follow ed by technical super io rit y ( 16%) , demand urg ency ( 12%) , and construction feasibility ( 12%) . The r esear ch pr ov ides an effectiv ely new metho d fo r the quantitative analy sis of impact factor s of smar t w ater const ruct ion, and the evaluation r esult s can prov ide import ant r eference fo r decision2making of w ater secto r and develo pment of w ater business.
Based on the T OE theor et ical fr amewo rk ( T echnolo gy2 Or ganizatio n2Environment) and the specific situation of smart water co nstr uction, the TOE framew ork w hich affects smart water constructio n was developed, and the effect s of each impact facto r o n the construction and development o f smar t w ater wer e analyzed from the technical, o rg anizat ional, and env iro nmental dimensions. T he technical dimensio n factors include the technica l superio rity, complex it y, compatibility , and o bser vability. T he org anizational dimension factor s include the const ruction necessity, demand urg ency , and co nstr uction feasibility . The envir on2 mental dimension factor s include the support sy st em, standard system, and info rmation securit y. On the basis, analyt ic hierarchy pr ocess ( AH P) w as used to determine the pr ior ity of the impact facto rs. The results showed that the or ganizatio nal dimensio n facto rs and technical dimension fact ors have hig h impacts on smart water construction w ith the weig ht o f 49% and 31% o ver the index system respect ively. Amo ng the impact factor s, const ruct ion necessity has the hig hest weig ht ( 25%) , follow ed by technical super io rit y ( 16%) , demand urg ency ( 12%) , and construction feasibility ( 12%) . The r esear ch pr ov ides an effectiv ely new metho d fo r the quantitative analy sis of impact factor s of smar t w ater const ruct ion, and the evaluation r esult s can prov ide import ant r eference fo r decision2making of w ater secto r and develo pment of w ater business.
Abstract:
Accurate and rapid determination of the distribution of contaminants is the main task for the investigation work of a contaminated site. As a new surveying tool for contaminated sites, direct push technology can be used for soil sample collection in the vadoze zone and aquifer, detection of aquifer parameters, and determination of pollutants. It has the advantages of fast, accurate, and free of cross-contamination. In this paper, the development and research progress of direct push technology was introduced, and the technology innovation was discussed.
Accurate and rapid determination of the distribution of contaminants is the main task for the investigation work of a contaminated site. As a new surveying tool for contaminated sites, direct push technology can be used for soil sample collection in the vadoze zone and aquifer, detection of aquifer parameters, and determination of pollutants. It has the advantages of fast, accurate, and free of cross-contamination. In this paper, the development and research progress of direct push technology was introduced, and the technology innovation was discussed.
Abstract:
"National River Linking Project (NRLP)" is a large-scale hydraulic engineering project that aims to reduce the persistent water shortage problems in India. In, this paper, describes the target planning and progress of the NRLPNational River Linking Project, was described, and introduces the program’s management system of this project and water policy in India was introduced. Due to the large scale of the project, it involves involved the deployment and utilization of water resources and utilization inof the many rivers of the South Peninsula, therefore several problems exist in the implementation of the project such as the funding stress, international development of transboundary rivers, and ecological environment. this paper addresses and analyzes the basic problems based on the project’s main benefit goals.
"National River Linking Project (NRLP)" is a large-scale hydraulic engineering project that aims to reduce the persistent water shortage problems in India. In, this paper, describes the target planning and progress of the NRLPNational River Linking Project, was described, and introduces the program’s management system of this project and water policy in India was introduced. Due to the large scale of the project, it involves involved the deployment and utilization of water resources and utilization inof the many rivers of the South Peninsula, therefore several problems exist in the implementation of the project such as the funding stress, international development of transboundary rivers, and ecological environment. this paper addresses and analyzes the basic problems based on the project’s main benefit goals.
Abstract:
Environmental Kuznets Curve (EKC) hypothesis has instructive significance to explore the relationship between environmental protection and economic development and to seek the coordinated development of economy and environment. Based on the analysis of the basic conception of EKC hypothesis, the research progress of the impact factors, theoretical developments, and empirical studies of EKC were illustrated in this paper, and the existing problems of the hypothesis were also discussed. Finally, it was noted that under the international trade conditions, the developing countries should study the clean technology, policy reformation, public education, and environmental law system from the developed countries, which can help them decrease the EKC turn point, flatten EKC curve, and seek for win-win relationship between economy and environment.
Environmental Kuznets Curve (EKC) hypothesis has instructive significance to explore the relationship between environmental protection and economic development and to seek the coordinated development of economy and environment. Based on the analysis of the basic conception of EKC hypothesis, the research progress of the impact factors, theoretical developments, and empirical studies of EKC were illustrated in this paper, and the existing problems of the hypothesis were also discussed. Finally, it was noted that under the international trade conditions, the developing countries should study the clean technology, policy reformation, public education, and environmental law system from the developed countries, which can help them decrease the EKC turn point, flatten EKC curve, and seek for win-win relationship between economy and environment.
Abstract:
Based on the daily data of precipitation and temperature of 30 basic meteorological stations during the period 1956-2010, twelve indices characterizing extreme climate change have been selected to analyze the temporal changes in precipitation and temperature extremes in the Hai River Basin. As per many other parts of the world, the analysis shows an increase in the intensity, frequency and duration of high temperature extremes and a decrease in that of cold extremes. The intensity of short-time precipitation extremes shows an increase and the frequency of heavy precipitation shows a decrease. The consecutive wet days shows a decrease, while the consecutive dry days shows an increase in recent decades, thus the dry pattern has been aggravated in the basin. The annual high temperature extremes and short-time precipitation extremes have begun to frequently occur since 1990s from interdecadal variations, the rainfall of long-duration precipitation events has shown a decrease however. The general warm and dry trend and precipitation concentration will have a negative impact on the agriculture production and water resources development. Meanwhile, the increase of short-time precipitation extremes may exacerbate the risk of local flood disaster in mountainous area as well as urban waterlogging.
Based on the daily data of precipitation and temperature of 30 basic meteorological stations during the period 1956-2010, twelve indices characterizing extreme climate change have been selected to analyze the temporal changes in precipitation and temperature extremes in the Hai River Basin. As per many other parts of the world, the analysis shows an increase in the intensity, frequency and duration of high temperature extremes and a decrease in that of cold extremes. The intensity of short-time precipitation extremes shows an increase and the frequency of heavy precipitation shows a decrease. The consecutive wet days shows a decrease, while the consecutive dry days shows an increase in recent decades, thus the dry pattern has been aggravated in the basin. The annual high temperature extremes and short-time precipitation extremes have begun to frequently occur since 1990s from interdecadal variations, the rainfall of long-duration precipitation events has shown a decrease however. The general warm and dry trend and precipitation concentration will have a negative impact on the agriculture production and water resources development. Meanwhile, the increase of short-time precipitation extremes may exacerbate the risk of local flood disaster in mountainous area as well as urban waterlogging.
Abstract:
The analysis of the night minimum flow data in the Districted Metered Area (DMA) of the water distribution system can characterize the real loss of DMA. The high-frequency and high-accuracy measured night flow data were analyzed, which indicated that the night flow data of DMA at different time periods are in normal distribution and the lowest night flow data is close to the real loss of DMA. In this study, the minimum night flow data from 2 AM to 4 AM in the early morning were analyzed based on the confidence level of 95.5% and confidence interval of (m-2d, m+2d).. The results showed that the minimum night flow of DMA after removing the abnormal values characterized by m-2dcan eliminate the effects of error and interference of measured data, and therefore obtain the real loss of DMA. This method can lower the evaluation error of night water demand, and facilitate the in-situ meter flow measurement to assess the DMA leakage level quickly.
The analysis of the night minimum flow data in the Districted Metered Area (DMA) of the water distribution system can characterize the real loss of DMA. The high-frequency and high-accuracy measured night flow data were analyzed, which indicated that the night flow data of DMA at different time periods are in normal distribution and the lowest night flow data is close to the real loss of DMA. In this study, the minimum night flow data from 2 AM to 4 AM in the early morning were analyzed based on the confidence level of 95.5% and confidence interval of (m-2d, m+2d).. The results showed that the minimum night flow of DMA after removing the abnormal values characterized by m-2dcan eliminate the effects of error and interference of measured data, and therefore obtain the real loss of DMA. This method can lower the evaluation error of night water demand, and facilitate the in-situ meter flow measurement to assess the DMA leakage level quickly.
Abstract:
Compared with the traditional determined hydrologic forecast, hydrologic ensemble forecast contains various uncertainties in the hydrologic forecast processes. Therefore, the accuracy and validity of hydrologic forecast have been improved theoretically. Meanwhile, the cognitive and predictive capabilities of the events such as storm, flood, and drought have been enhanced in the practical applications. The hydrologic ensemble forecast can provide more accurate and useful information in flood control, drought relief, and sustainable water resources management. In this paper, we firstly reviewed the history of hydrologic ensemble forecast, and then we summarized the research progresses in theory, methods, as well as the applications and operational hydrologic ensemble forecast. We focused on two research aspects of the pre-processing and post-processing issues in an effort to provide a useful platform for the development of hydrologic ensemble prediction. The perspectives and recommendations on this subject were provided. This paper is of important significance in the future development of hydrologic ensemble forecast research.
Compared with the traditional determined hydrologic forecast, hydrologic ensemble forecast contains various uncertainties in the hydrologic forecast processes. Therefore, the accuracy and validity of hydrologic forecast have been improved theoretically. Meanwhile, the cognitive and predictive capabilities of the events such as storm, flood, and drought have been enhanced in the practical applications. The hydrologic ensemble forecast can provide more accurate and useful information in flood control, drought relief, and sustainable water resources management. In this paper, we firstly reviewed the history of hydrologic ensemble forecast, and then we summarized the research progresses in theory, methods, as well as the applications and operational hydrologic ensemble forecast. We focused on two research aspects of the pre-processing and post-processing issues in an effort to provide a useful platform for the development of hydrologic ensemble prediction. The perspectives and recommendations on this subject were provided. This paper is of important significance in the future development of hydrologic ensemble forecast research.
Abstract:
The instantaneous peak flow (IPF) is the basic information for hydraulic design，construction and management. It also has an important influence on the investment and safety of hydraulic structures. However, the IPF records in Tibet are generally short in length, while mean daily flow (MDF) records are relatively longer. In this study, the IPF records are extended by analyzing the relationship between corresponding IPF and MDF records. The results show that the ratio between IPF and MDF is stable in most of hydrological stations. The relative error between estimated IPF and observed IPF is less than 10%. The results of flood frequency analysis using extended IPF series are more reasonable than that using the measured IPF series. For the stations with limited measured MDF, the HIMS model is used to extend the available MDF. The HIMS model is applied in three representative rivers of Tibet: the Nianchu river, Lhasa river and Niang river. The results show that the model has a good performance in both daily and peak flow simulation. The end year of IPF series in the three representative hydrological stations has been extended from 2000 to 2010 by the simulation results of HIMS and the relationship between IPF and MDF.
The instantaneous peak flow (IPF) is the basic information for hydraulic design，construction and management. It also has an important influence on the investment and safety of hydraulic structures. However, the IPF records in Tibet are generally short in length, while mean daily flow (MDF) records are relatively longer. In this study, the IPF records are extended by analyzing the relationship between corresponding IPF and MDF records. The results show that the ratio between IPF and MDF is stable in most of hydrological stations. The relative error between estimated IPF and observed IPF is less than 10%. The results of flood frequency analysis using extended IPF series are more reasonable than that using the measured IPF series. For the stations with limited measured MDF, the HIMS model is used to extend the available MDF. The HIMS model is applied in three representative rivers of Tibet: the Nianchu river, Lhasa river and Niang river. The results show that the model has a good performance in both daily and peak flow simulation. The end year of IPF series in the three representative hydrological stations has been extended from 2000 to 2010 by the simulation results of HIMS and the relationship between IPF and MDF.
Abstract:
As a quantitative indicator of drought, drought index plays an important role in the monitoring and forecasting of drought and water resources management, and it is also a useful research tool in the field of hydrology and water resources. Over the last decade, the primary progress in the development and improvement of drought index involved the introduction of evapotranspiration as a factor of the index calculation, which can improve the parameter accuracy in model simulation and combine with the model algorithm of hydrological process. The application of drought index included the inversion and prediction of regional drought, crop yield prediction, forest fire detection, and paleoclimate reconstruction. The development and application of drought index provided an effective tool for regional drought monitoring and water resources management; however, the quantification and comprehensive evaluation of drought index should be considered as research priorities, which can help improve the accuracy and reliability of model monitoring and thus provide new options and technical approaches for rapid monitoring of drought.
As a quantitative indicator of drought, drought index plays an important role in the monitoring and forecasting of drought and water resources management, and it is also a useful research tool in the field of hydrology and water resources. Over the last decade, the primary progress in the development and improvement of drought index involved the introduction of evapotranspiration as a factor of the index calculation, which can improve the parameter accuracy in model simulation and combine with the model algorithm of hydrological process. The application of drought index included the inversion and prediction of regional drought, crop yield prediction, forest fire detection, and paleoclimate reconstruction. The development and application of drought index provided an effective tool for regional drought monitoring and water resources management; however, the quantification and comprehensive evaluation of drought index should be considered as research priorities, which can help improve the accuracy and reliability of model monitoring and thus provide new options and technical approaches for rapid monitoring of drought.
Abstract:
With the r apid development o f meso scale numer ical at mospher ic model WRF in r ecent y ears, its application is wider and w ider. In or der to ex plain the mechanism, r eveal the develo pment directio n and pr ov ide refer ence for r elated fields research2 er s, WRF model sy stem is int roduced, it is discussed that the influence o f parameterized phy sical pr ocesses, data assimilatio n and reasonable spat ial scale o n the simulation effect o f WRF model. Related studies have shown that: ( 1) differ ent par ameter2 ized phy sical processes need to be chosen in different reg ion and different time; ( 2) the common data assimilation method is 3DVar data assimilatio n at present, hybr id data assimilatio n may be a better met ho d to impr ove the simulatio n effect of WRF model; ( 3) reasonable spat ial scales need to be cho sen because not the hig her hor izo nt al reso lution, t he better simulat ion effect for a ll research; ( 4) WRF mo del has g oo d simulat ion effect , hig h pr ediction accuracy , there is mo re w ide applicat ion.
With the r apid development o f meso scale numer ical at mospher ic model WRF in r ecent y ears, its application is wider and w ider. In or der to ex plain the mechanism, r eveal the develo pment directio n and pr ov ide refer ence for r elated fields research2 er s, WRF model sy stem is int roduced, it is discussed that the influence o f parameterized phy sical pr ocesses, data assimilatio n and reasonable spat ial scale o n the simulation effect o f WRF model. Related studies have shown that: ( 1) differ ent par ameter2 ized phy sical processes need to be chosen in different reg ion and different time; ( 2) the common data assimilation method is 3DVar data assimilatio n at present, hybr id data assimilatio n may be a better met ho d to impr ove the simulatio n effect of WRF model; ( 3) reasonable spat ial scales need to be cho sen because not the hig her hor izo nt al reso lution, t he better simulat ion effect for a ll research; ( 4) WRF mo del has g oo d simulat ion effect , hig h pr ediction accuracy , there is mo re w ide applicat ion.
Abstract:
The objective of this study is to evaluate the applicability of SWAT model to agricultural drought evaluation for regions without or lack of soil moisture data. For this purpose, the SWAT model was applied to simulate the hydrological process in the Bahe watershed of the upper Weihe River. The soil water content was obtained and it was used to calculate the relative soil moisture. The calculated relative soil moisture was regarded as the evaluation index of agricultural drought. The results showed that severe spring droughts occurred in 2001 and 2002 and summer drought occurred in 2003 in the Bahe watershed, which was in accordance with the actual conditions. . Therefore, SWAT model is applicable to agricultural drought evaluation for the area lack of soil moisture data.
The objective of this study is to evaluate the applicability of SWAT model to agricultural drought evaluation for regions without or lack of soil moisture data. For this purpose, the SWAT model was applied to simulate the hydrological process in the Bahe watershed of the upper Weihe River. The soil water content was obtained and it was used to calculate the relative soil moisture. The calculated relative soil moisture was regarded as the evaluation index of agricultural drought. The results showed that severe spring droughts occurred in 2001 and 2002 and summer drought occurred in 2003 in the Bahe watershed, which was in accordance with the actual conditions. . Therefore, SWAT model is applicable to agricultural drought evaluation for the area lack of soil moisture data.
Abstract:
Static cone penetration test (CPT) as is an in situ test, which is was widely used in the engineering practice. Based on recently research results, thise paper systematically introduced sums up the research and development course in of CPT and summarized the research progress of the, such as instrument development, cone resistance theoretical research of cone resistance, model test, numerical simulation, and engineering application of CPT. Empirical formula of to calculate the soil parameters using CPT on for different industries and different areas were summarized. The paper pointed out that iIt is necessary to fully consider the engineering characteristics of regional soil when using in application of the CPT results. Moreover, It should be point out that the theoretical analysis of excess pore water pressure, analytic solution of cylindrical hole space problem, and numerical analysis simulation for large deformation analysis theory need to be further improved..
Static cone penetration test (CPT) as is an in situ test, which is was widely used in the engineering practice. Based on recently research results, thise paper systematically introduced sums up the research and development course in of CPT and summarized the research progress of the, such as instrument development, cone resistance theoretical research of cone resistance, model test, numerical simulation, and engineering application of CPT. Empirical formula of to calculate the soil parameters using CPT on for different industries and different areas were summarized. The paper pointed out that iIt is necessary to fully consider the engineering characteristics of regional soil when using in application of the CPT results. Moreover, It should be point out that the theoretical analysis of excess pore water pressure, analytic solution of cylindrical hole space problem, and numerical analysis simulation for large deformation analysis theory need to be further improved..
Abstract:
A proposed water transfer tunnel will be excavated with tunnel boring machine (TBM) in the surrounding type-III rock. The shotcrete and reinforced concrete segment serve as the initial support and permanent liner, respectively. The considerable internal and external water pressures are loaded on the liner, with the water head values of 110 m and 200 m, respectively. In this paper, in consideration of the contact relationship between segments, the contact relationship between segment and surrounding structure, and the cooperative working performance of reinforcement bars and concrete, the stress deformation characteristics of the liner under high water pressures are analyzed using the finite element method. The results showed that the external water pressure is the decisive load for the design of tunnel liner, and therefore a simplified model of segment liner design was proposed. The results suggested that it is feasible to use the reinforced concrete segment as tunnel lining under the conditions of the surrounding rock, support, and water pressure shown in the study.
A proposed water transfer tunnel will be excavated with tunnel boring machine (TBM) in the surrounding type-III rock. The shotcrete and reinforced concrete segment serve as the initial support and permanent liner, respectively. The considerable internal and external water pressures are loaded on the liner, with the water head values of 110 m and 200 m, respectively. In this paper, in consideration of the contact relationship between segments, the contact relationship between segment and surrounding structure, and the cooperative working performance of reinforcement bars and concrete, the stress deformation characteristics of the liner under high water pressures are analyzed using the finite element method. The results showed that the external water pressure is the decisive load for the design of tunnel liner, and therefore a simplified model of segment liner design was proposed. The results suggested that it is feasible to use the reinforced concrete segment as tunnel lining under the conditions of the surrounding rock, support, and water pressure shown in the study.
Abstract:
Wetlands and aAtmosphere constantly engaged in the exchange of energy and material constantly, that is , free water surface of wetland and dense vegetation was are in the process of evapotranspirationthrough evapo-transpiration to enter into the atmosphere and a part of water returns to the groundwater as precipitation, thereby increasing the so that water vapour injected into the atmosphere， then formed the rain and returned to the ground, thereby it improved local humidity and precipitation. In this paper, Based on the precipitation data from 1974～2010 of Hengshui Lake and twenty- four24 nearby rRainfall sStations from 1974 to 2010 were used to calculate of periphery ， this article figured out the average precipitation of the Hengshui Lake District ，10- km radius affected zone, 10～2010- to 20- km circular affected zone， and 20- to～30- km circular affected zone. It analyzed theThe effects of the wetland of Hengshui Lake on precipitation were analyzed, and the main reasons were investigated based on the change regularity of different affected zone of Hengshui Lake wetland, and explore the main reason through precipitation formation mechanism of precipitation. The result showsed: that the precipitation decreases Hengshui Lake wetland from the near to the distant distance of the Hengshui Lake Wetland, indicating was obviously decreasing, it revealed that Hengshui Lake wetland has an adjustment function the adjustment effects of the wetland onto the climate of surrounding regional climatearea.
Wetlands and aAtmosphere constantly engaged in the exchange of energy and material constantly, that is , free water surface of wetland and dense vegetation was are in the process of evapotranspirationthrough evapo-transpiration to enter into the atmosphere and a part of water returns to the groundwater as precipitation, thereby increasing the so that water vapour injected into the atmosphere， then formed the rain and returned to the ground, thereby it improved local humidity and precipitation. In this paper, Based on the precipitation data from 1974～2010 of Hengshui Lake and twenty- four24 nearby rRainfall sStations from 1974 to 2010 were used to calculate of periphery ， this article figured out the average precipitation of the Hengshui Lake District ，10- km radius affected zone, 10～2010- to 20- km circular affected zone， and 20- to～30- km circular affected zone. It analyzed theThe effects of the wetland of Hengshui Lake on precipitation were analyzed, and the main reasons were investigated based on the change regularity of different affected zone of Hengshui Lake wetland, and explore the main reason through precipitation formation mechanism of precipitation. The result showsed: that the precipitation decreases Hengshui Lake wetland from the near to the distant distance of the Hengshui Lake Wetland, indicating was obviously decreasing, it revealed that Hengshui Lake wetland has an adjustment function the adjustment effects of the wetland onto the climate of surrounding regional climatearea.
Abstract:
Based on the monthly precipitation data of 25 meteorological stations in the Haihe River Basin from 1960 to 2010, the inter 2annual precipitation characteristics in the Haihe River Basin were analyzed using the linear regression and cumulative a 2 nomaly curve methods. T he probability distribution of precipitation was analyzed using the Pearson III curve method, and the spatial variation of precipitation was analyzed using the spatial interpolation method. T he results showed that (1) precipitation in the Haihe River Basin has a slightly decreasing trend in recent 51 years, and the decreasing trend is stable recently; ( 2) there is a trend with more wet years while less dry years in the Haihe River Basin and the trend is increasing; (3) seasonal variation of precipitation is obvious; and (4) precipitation decreases trend from the south to the north.
Based on the monthly precipitation data of 25 meteorological stations in the Haihe River Basin from 1960 to 2010, the inter 2annual precipitation characteristics in the Haihe River Basin were analyzed using the linear regression and cumulative a 2 nomaly curve methods. T he probability distribution of precipitation was analyzed using the Pearson III curve method, and the spatial variation of precipitation was analyzed using the spatial interpolation method. T he results showed that (1) precipitation in the Haihe River Basin has a slightly decreasing trend in recent 51 years, and the decreasing trend is stable recently; ( 2) there is a trend with more wet years while less dry years in the Haihe River Basin and the trend is increasing; (3) seasonal variation of precipitation is obvious; and (4) precipitation decreases trend from the south to the north.
Abstract:
The impacts of human activities and dry climate aggravate the water pollution and eutrophication in the Baiyang Lake. Through the analysis of hydro 2chemical compositions of the water, five indexes[Chla, TN, T P, COD Mn, and SD] , which are re 2 lated to water eutrophication, are selected as evaluation parameters, and the comprehensive nutrition index method is adopted to determine the water eutrophication type. T he results of water quality monitoring data show that the type of water is CNaII, and the lake is in mesotrophic or eutrophic state determined by the comprehensive nutrition index method. The principal component analysis results show that TP is the main factor to cause water pollution in the lake. According to the analysis of diatom and its combination, the diatom in the lake is characterized by the combination of eutrophic species Cyclotellameneghiniana ( 20. 43%) and Cyclostep hanos tholif ormis ( 25. 40%) , which indicates that the lake is in the eutrophication state and water environment is in danger.
The impacts of human activities and dry climate aggravate the water pollution and eutrophication in the Baiyang Lake. Through the analysis of hydro 2chemical compositions of the water, five indexes[Chla, TN, T P, COD Mn, and SD] , which are re 2 lated to water eutrophication, are selected as evaluation parameters, and the comprehensive nutrition index method is adopted to determine the water eutrophication type. T he results of water quality monitoring data show that the type of water is CNaII, and the lake is in mesotrophic or eutrophic state determined by the comprehensive nutrition index method. The principal component analysis results show that TP is the main factor to cause water pollution in the lake. According to the analysis of diatom and its combination, the diatom in the lake is characterized by the combination of eutrophic species Cyclotellameneghiniana ( 20. 43%) and Cyclostep hanos tholif ormis ( 25. 40%) , which indicates that the lake is in the eutrophication state and water environment is in danger.
Abstract:
Thro ug h the analysis of t he technique, envir onment, law , and eco nomy in the manag ement and operatio n o f inter2basin water transfer projects abro ad, this paper summar ized the successful ex per ience o f int er2basin w ater tr ansfer pr ojects in the wo rld fr om the aspects of leg islat ion, w ater r ig ht s, water pr ice, unified manag ement o f water resources, investment manag ement of eng ineering const ruct ion, and management o per ation mode, w hich can pro vide t he refer ence fo r the o per ation of inter2basin water transfer pro jects in China.
Thro ug h the analysis of t he technique, envir onment, law , and eco nomy in the manag ement and operatio n o f inter2basin water transfer projects abro ad, this paper summar ized the successful ex per ience o f int er2basin w ater tr ansfer pr ojects in the wo rld fr om the aspects of leg islat ion, w ater r ig ht s, water pr ice, unified manag ement o f water resources, investment manag ement of eng ineering const ruct ion, and management o per ation mode, w hich can pro vide t he refer ence fo r the o per ation of inter2basin water transfer pro jects in China.
Periodical information
Competent Authority:Department of Water Resources of Hebei Procince
Sponsored by:Hebei Institute of Water Resources
Chief Editor :ZHANG Shuantang
Edited and Published by:The Editorial Dept South-to-North Water Transfers and Water Science &Technology
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