Volume 22,Issue 2,2024 Table of Contents
2024, 22(2):209-214.
Abstract:
Impacts of global climate change and the high-intensity human activities have led to changes in the water cycle in the Yangtze River basin and the contradiction between the water supply and water demand in the river basin and its associated urban agglomerations. This issue is especially highlighted in the water supply security of coastal cities, such as the Shanghai is in the lower reaches of Yangtze River, and has become one of the important issues of great concern for the protection of the Yangtze River. This study examines how changes in the environment affect the risk of water supply security in Shanghai. It specifically focuses on the Qingcaosha reservoir system. This text analyzes the impact of extreme droughts on current and future urban water supplies in Shanghai. It discusses the pressure on the water supply due to the interaction between the fresh water of the Yangtze River and the salty tides in the estuary. It also highlights the challenges faced in managing Shanghai's urban water supply, including the integrated use of engineering and non-engineering measures such as early warning, forecasting and scheduling. To improve water supply safety and security, it is recommended to implement systematic thinking and strategic planning, upgrade the level of systematic intelligence and smart management for urban water supply safety, and improve the management system for water supply safety and security.
Impacts of global climate change and the high-intensity human activities have led to changes in the water cycle in the Yangtze River basin and the contradiction between the water supply and water demand in the river basin and its associated urban agglomerations. This issue is especially highlighted in the water supply security of coastal cities, such as the Shanghai is in the lower reaches of Yangtze River, and has become one of the important issues of great concern for the protection of the Yangtze River. This study examines how changes in the environment affect the risk of water supply security in Shanghai. It specifically focuses on the Qingcaosha reservoir system. This text analyzes the impact of extreme droughts on current and future urban water supplies in Shanghai. It discusses the pressure on the water supply due to the interaction between the fresh water of the Yangtze River and the salty tides in the estuary. It also highlights the challenges faced in managing Shanghai's urban water supply, including the integrated use of engineering and non-engineering measures such as early warning, forecasting and scheduling. To improve water supply safety and security, it is recommended to implement systematic thinking and strategic planning, upgrade the level of systematic intelligence and smart management for urban water supply safety, and improve the management system for water supply safety and security.
2024, 22(2):215-227.
Abstract:
The uneven spatiotemporal distribution of water resources has gradually become a significant constraining factor for regional development, due to mismatches with population, productivity, and land layout. In order to meet the demands of human socioeconomic development, a series of hydraulic engineering and water supply facilities have been constructed to alter the natural distribution pattern of water resources and enhance the spatial equilibrium of water resource allocation. Water resource equilibrium allocation is not simply a matter of allocating a single water source to a single user, but involves complex water quantity distribution composed of multiple water sources, users, and hierarchical engineering. Therefore, it is essential to analyze the spatial equilibrium of water allocation from the perspective of the overall water allocation system.An evaluation index system has been established, consisting of four subsystems: water source equilibrium, water supply facility equilibrium, unit equilibrium, and user equilibrium. The water source equilibrium subsystem employs the matching degree between the water supply proportion of each water source and its available water quantity proportion as an indicator. The water supply facility equilibrium subsystem selects the matching degree between the water supply proportion of each water supply facility and the scale of water supply as an indicator. The unit equilibrium subsystem treats each administrative region as a computational unit and utilizes the matching degree between the population of each unit and the water resources as an indicator. The user equilibrium subsystem uses the matching degree between the water supply proportion of each water user and the demand for water as an indicator. Subsequently, 12 different scenarios are designed, and the entropy weight TOPSIS method is utilized to comprehensively evaluate the spatial equilibrium level of water resources. The entropy weight TOPSIS method is an effective multi-attribute decision-making analysis approach that fully considers the importance of each attribute, thereby enhancing the accuracy and reliability of decision-making by avoiding subjectivity and uncertainty. In practical applications, it is necessary to select appropriate methods based on specific circumstances and pay attention to data quality and standardization.The results indicate that the scheme involving external water diversion is the optimal solution, with a relative closeness degree of 0.841, while the scheme without water resource allocation is the worst, with a relative closeness degree of 0.281. Regarding the adjustment of allocation methods, in the scheme without water resource allocation, the inability to conduct inter-basin water transfer and the widespread inadequacy of local water resources to meet demands lead to a 0.275 decrease in relative closeness compared to the existing situation. The scheme involving water source substitution exhibits an increase of 0.084 in relative closeness, and the scheme expanding the water supply range of water plants shows an increase of 0.047 in relative closeness compared to the existing situation. In terms of adjusting water sources, the scheme increasing the index of external water diversion demonstrates an increase of 0.285 in relative closeness compared to the existing situation, while the scheme increasing the index of groundwater shows an increase of 0.220 in relative closeness. It is evident that the effect of increasing the index of external water diversion is more significant. In terms of adjusting water demand, reducing water demand can improve the spatial equilibrium of water resources, while increasing water demand can lower it. The reduction of agricultural water demand yields the best effect, followed by the reduction of industrial water demand, and finally the reduction of domestic water demand, with relative closeness degrees increasing by 0.244, 0.081, and 0.043, respectively, compared to the existing scheme.This method combines water resource allocation with spatial equilibrium evaluation and utilizes the entropy weight TOPSIS method to comprehensively assess the spatial equilibrium level of different schemes based on 12 allocation scenarios in Changyi City. This approach ensures that the results are more rational and objective, while also providing reference for future water resource allocation work in Changyi City.
The uneven spatiotemporal distribution of water resources has gradually become a significant constraining factor for regional development, due to mismatches with population, productivity, and land layout. In order to meet the demands of human socioeconomic development, a series of hydraulic engineering and water supply facilities have been constructed to alter the natural distribution pattern of water resources and enhance the spatial equilibrium of water resource allocation. Water resource equilibrium allocation is not simply a matter of allocating a single water source to a single user, but involves complex water quantity distribution composed of multiple water sources, users, and hierarchical engineering. Therefore, it is essential to analyze the spatial equilibrium of water allocation from the perspective of the overall water allocation system.An evaluation index system has been established, consisting of four subsystems: water source equilibrium, water supply facility equilibrium, unit equilibrium, and user equilibrium. The water source equilibrium subsystem employs the matching degree between the water supply proportion of each water source and its available water quantity proportion as an indicator. The water supply facility equilibrium subsystem selects the matching degree between the water supply proportion of each water supply facility and the scale of water supply as an indicator. The unit equilibrium subsystem treats each administrative region as a computational unit and utilizes the matching degree between the population of each unit and the water resources as an indicator. The user equilibrium subsystem uses the matching degree between the water supply proportion of each water user and the demand for water as an indicator. Subsequently, 12 different scenarios are designed, and the entropy weight TOPSIS method is utilized to comprehensively evaluate the spatial equilibrium level of water resources. The entropy weight TOPSIS method is an effective multi-attribute decision-making analysis approach that fully considers the importance of each attribute, thereby enhancing the accuracy and reliability of decision-making by avoiding subjectivity and uncertainty. In practical applications, it is necessary to select appropriate methods based on specific circumstances and pay attention to data quality and standardization.The results indicate that the scheme involving external water diversion is the optimal solution, with a relative closeness degree of 0.841, while the scheme without water resource allocation is the worst, with a relative closeness degree of 0.281. Regarding the adjustment of allocation methods, in the scheme without water resource allocation, the inability to conduct inter-basin water transfer and the widespread inadequacy of local water resources to meet demands lead to a 0.275 decrease in relative closeness compared to the existing situation. The scheme involving water source substitution exhibits an increase of 0.084 in relative closeness, and the scheme expanding the water supply range of water plants shows an increase of 0.047 in relative closeness compared to the existing situation. In terms of adjusting water sources, the scheme increasing the index of external water diversion demonstrates an increase of 0.285 in relative closeness compared to the existing situation, while the scheme increasing the index of groundwater shows an increase of 0.220 in relative closeness. It is evident that the effect of increasing the index of external water diversion is more significant. In terms of adjusting water demand, reducing water demand can improve the spatial equilibrium of water resources, while increasing water demand can lower it. The reduction of agricultural water demand yields the best effect, followed by the reduction of industrial water demand, and finally the reduction of domestic water demand, with relative closeness degrees increasing by 0.244, 0.081, and 0.043, respectively, compared to the existing scheme.This method combines water resource allocation with spatial equilibrium evaluation and utilizes the entropy weight TOPSIS method to comprehensively assess the spatial equilibrium level of different schemes based on 12 allocation scenarios in Changyi City. This approach ensures that the results are more rational and objective, while also providing reference for future water resource allocation work in Changyi City.
2024, 22(2):228-236.
Abstract:
With the rapid development of the social economy in Henan Province, runoff reduction is more serious. Attribution analysis of runoff variation can provide a scientific basis for water resources management. Henan Province spans the Yangtze River, the Yellow River, the Huaihe River, and the Haihe River, the water system is complex. The climate is diverse, and the economic development is unbalanced among different places, so the impact of climate change and human activities on runoff variation is different. In the past, some studies on the attribution analysis of runoff variation were carried out in Henan Province, but the conclusions are not consistent. To get a relatively comprehensive and objective attribution rate, it is necessary to carry out the attribution analysis of runoff variation in representative basins in Henan Province based on accurate meteorological and hydrological data.The Weihe River basin, Yiluohe River basin, Hongruhe River basin, and Tanghe River basin in Henan Province were selected as study basins, which are sub-basins of the Haihe River basin, the Yellow River basin, the Huaihe River basin, and the Yangtze River basin, respectively, and their control hydrologic stations are Yuancun station, Heishiguan station, Bantai station, and Guotan station. Based on annual runoff and precipitation data of the four study basins from 1961 to 2022, and annual potential evapotranspiration by the Penman-Monteith method from National Climate Center, the Mann-Kendall mutation test and double cumulative curves method were used to analyze the mutation years of annual runoff depth series of control hydrologic stations, and the change trends of annual runoff depth of control stations, annual precipitation and annual potential evapotranspiration of the study basins were also analyzed. Annual potential evapotranspiration was compared with observed annual evaporation. The elastic coefficient method based on the Budyko hypothesis was applied to assess the attribution rate of climate change and human activities to runoff variation.The results showed that: (1) The annual runoff depth of the four hydrologic stations showed a decreasing trend. The annual precipitation of the four study basins showed an insignificant decreasing trend. The potential evapotranspiration also indicated a decreasing trend and the decreasing trend was significant in the Weihe River basin, Hongruhe River basin, and Tanghe River basin, but not significant in the Yiluohe River basin. The changing trend of annual potential evapotranspiration and observed annual evaporation at the four weather stations was consistent. (2) The mutation of annual runoff of Yuancun station, Heishiguan station, Bantai sation, and Guotan station occurred in 1977, 1985, 2008, and 2010, respectively. (3) The contribution rates of climate change to runoff reduction were less than 7% in the Weihe River and Yiluohe River basins, and about 12%?18% in the Hongruhe River and Tanghe River basins. The contribution rates of human activities were about 93%?97% in the Weihe River and Yiluohe River basins, and about 82%?88% in the Weihe River and Tanghe River basins. The climate change showed low contribution rates because of the insignificant decrease in precipitation and the decrease in potential evapotranspiration . Therefore, it can be seen that human activities were the main influencing factor of runoff reduction in the four study river basins.
With the rapid development of the social economy in Henan Province, runoff reduction is more serious. Attribution analysis of runoff variation can provide a scientific basis for water resources management. Henan Province spans the Yangtze River, the Yellow River, the Huaihe River, and the Haihe River, the water system is complex. The climate is diverse, and the economic development is unbalanced among different places, so the impact of climate change and human activities on runoff variation is different. In the past, some studies on the attribution analysis of runoff variation were carried out in Henan Province, but the conclusions are not consistent. To get a relatively comprehensive and objective attribution rate, it is necessary to carry out the attribution analysis of runoff variation in representative basins in Henan Province based on accurate meteorological and hydrological data.The Weihe River basin, Yiluohe River basin, Hongruhe River basin, and Tanghe River basin in Henan Province were selected as study basins, which are sub-basins of the Haihe River basin, the Yellow River basin, the Huaihe River basin, and the Yangtze River basin, respectively, and their control hydrologic stations are Yuancun station, Heishiguan station, Bantai station, and Guotan station. Based on annual runoff and precipitation data of the four study basins from 1961 to 2022, and annual potential evapotranspiration by the Penman-Monteith method from National Climate Center, the Mann-Kendall mutation test and double cumulative curves method were used to analyze the mutation years of annual runoff depth series of control hydrologic stations, and the change trends of annual runoff depth of control stations, annual precipitation and annual potential evapotranspiration of the study basins were also analyzed. Annual potential evapotranspiration was compared with observed annual evaporation. The elastic coefficient method based on the Budyko hypothesis was applied to assess the attribution rate of climate change and human activities to runoff variation.The results showed that: (1) The annual runoff depth of the four hydrologic stations showed a decreasing trend. The annual precipitation of the four study basins showed an insignificant decreasing trend. The potential evapotranspiration also indicated a decreasing trend and the decreasing trend was significant in the Weihe River basin, Hongruhe River basin, and Tanghe River basin, but not significant in the Yiluohe River basin. The changing trend of annual potential evapotranspiration and observed annual evaporation at the four weather stations was consistent. (2) The mutation of annual runoff of Yuancun station, Heishiguan station, Bantai sation, and Guotan station occurred in 1977, 1985, 2008, and 2010, respectively. (3) The contribution rates of climate change to runoff reduction were less than 7% in the Weihe River and Yiluohe River basins, and about 12%?18% in the Hongruhe River and Tanghe River basins. The contribution rates of human activities were about 93%?97% in the Weihe River and Yiluohe River basins, and about 82%?88% in the Weihe River and Tanghe River basins. The climate change showed low contribution rates because of the insignificant decrease in precipitation and the decrease in potential evapotranspiration . Therefore, it can be seen that human activities were the main influencing factor of runoff reduction in the four study river basins.
2024, 22(2):237-246.
Abstract:
Water is the most crucial and fundamental resource for driving social progress. To address the uneven distribution of water resource-related issues and the disparity between population and economic demands, China implemented a national water network project aimed at systematically allocating and efficiently utilizing regional water resources. The operation of the Middle Route of the South-to-North Water Transfers Project significantly enhanced Beijing's water supply system, leading to a multi-source water supply pattern that effectively improved urban water resource security. To tackle the challenges posed by climate change, Beijing proposed various water resource allocation principles to optimize the distribution of water for domestic, industrial, and ecological purposes, supporting the city's rapid development. However, how water resources are allocated, and what are the significant impacts and benefits? Thus, it is imperative to establish a comprehensive evaluation system that thoroughly assesses the beneficial effects of water resource allocation and utilization to enhance the resilience of the urban water resources system scientifically.This study examined the benefits of multiple water resources joint allocation projects in Beijing using data from 2010 to 2021. This study systematically analyzed the effects of joint allocation and comprehensive utilization of water resources by identifying their impacts on the "structure-society-economy-ecology". An evaluation system of comprehensive benefits was constructed using the comprehensive index evaluation method of entropy weight. The comprehensive benefits of water resources allocation and utilization were analyzed and evaluated, thereby examining the changing characteristics of the benefit index across four dimensions: social impact, economic impact, ecological environment, and system structure.The results indicated that Beijing's water structure became more resilient according to industrial structure adjustments, the active promotion of water-saving initiatives, and the emphasis on ecological environment protection. Water consumption in the industrial and agricultural sectors has decreased, while in the domestic and environmental sectors has increased. Urban water resource allocation effectively improved the equilibrium state of water resource carrying capacity in Beijing. However, due to significant spatial differences in the economy and population and the influence of changing water conditions, the suitability of water supply for economic and social development exhibited obvious differentiation, leading to a pronounced spatial imbalance between regional water supply and population. The joint allocation of water resources in Beijing had varying degrees of impact on structural balance, social impact, economic impact, and ecological environment benefits, with the ecological environment showing significant improvement. Additionally, the annual enhancement of the comprehensive benefit index indicates that water resource allocation in Beijing has contributed to the city's sustainable development.In light of the above analysis, to further improve the efficiency and scientific management of water resource allocation in complex water conditions, it is significant to promote the construction of the water resource market system, continuously enhance the water resource management mechanism, and actively involve society communities in the sustainable use of water resources. It is highly recommended that an urban water economic model should be developed to further improve the effectiveness assessment of the urban water resources allocation system and the development of optimization plans .
Water is the most crucial and fundamental resource for driving social progress. To address the uneven distribution of water resource-related issues and the disparity between population and economic demands, China implemented a national water network project aimed at systematically allocating and efficiently utilizing regional water resources. The operation of the Middle Route of the South-to-North Water Transfers Project significantly enhanced Beijing's water supply system, leading to a multi-source water supply pattern that effectively improved urban water resource security. To tackle the challenges posed by climate change, Beijing proposed various water resource allocation principles to optimize the distribution of water for domestic, industrial, and ecological purposes, supporting the city's rapid development. However, how water resources are allocated, and what are the significant impacts and benefits? Thus, it is imperative to establish a comprehensive evaluation system that thoroughly assesses the beneficial effects of water resource allocation and utilization to enhance the resilience of the urban water resources system scientifically.This study examined the benefits of multiple water resources joint allocation projects in Beijing using data from 2010 to 2021. This study systematically analyzed the effects of joint allocation and comprehensive utilization of water resources by identifying their impacts on the "structure-society-economy-ecology". An evaluation system of comprehensive benefits was constructed using the comprehensive index evaluation method of entropy weight. The comprehensive benefits of water resources allocation and utilization were analyzed and evaluated, thereby examining the changing characteristics of the benefit index across four dimensions: social impact, economic impact, ecological environment, and system structure.The results indicated that Beijing's water structure became more resilient according to industrial structure adjustments, the active promotion of water-saving initiatives, and the emphasis on ecological environment protection. Water consumption in the industrial and agricultural sectors has decreased, while in the domestic and environmental sectors has increased. Urban water resource allocation effectively improved the equilibrium state of water resource carrying capacity in Beijing. However, due to significant spatial differences in the economy and population and the influence of changing water conditions, the suitability of water supply for economic and social development exhibited obvious differentiation, leading to a pronounced spatial imbalance between regional water supply and population. The joint allocation of water resources in Beijing had varying degrees of impact on structural balance, social impact, economic impact, and ecological environment benefits, with the ecological environment showing significant improvement. Additionally, the annual enhancement of the comprehensive benefit index indicates that water resource allocation in Beijing has contributed to the city's sustainable development.In light of the above analysis, to further improve the efficiency and scientific management of water resource allocation in complex water conditions, it is significant to promote the construction of the water resource market system, continuously enhance the water resource management mechanism, and actively involve society communities in the sustainable use of water resources. It is highly recommended that an urban water economic model should be developed to further improve the effectiveness assessment of the urban water resources allocation system and the development of optimization plans .
2024, 22(2):247-257,360.
Abstract:
Determining the soil water characteristic curve in the high altitude seasonal frozen zone is crucial to understand its soil water movement characteristics. However, today's research on modeling soil water characteristic curves in the high altitude seasonal frozen zones focuses more on the effects of permafrost, vegetation degradation, and other factors on the change of soil moisture content, and lacks the analysis of the applicability of soil water characteristic curves.The volumetric soil water content and soil matrix potential were measured by in-situ observation experiment, selected three models, Van Genuchten (VG), Brooks-Corey (BC), and Campbell for fitting, and analyzed the applicability of the soil water characteristic curve model in the Naqu watershed of the Nujiang River source area using the root-mean-square error and the coefficient of determination as the evaluation indexes. The results showed that: (1) The ERMS of the VG model was 66.6% and 56.9% lower than that of the BC and Campbell models, respectively, and the R2 of the VG model was higher than that of the BC and Campbell models (on average, 2.0% and 0.9% higher, respectively), and the VG model was considered sufficiently accurate as far as the R2 and the ERMS were concerned ( R2 > 0.97,ERMS ≤ 0.011cm3/cm3). While the BC model had an overall poor fitting effect, with an average R2 of 0.97 and an ERMS of 0.018cm3/cm3, the Campbell model had strong applicability in the soil surface layer, with an average R2 of 0.99 and an ERMS of 0.006cm3/cm3; (2) The parameter θr of the VG model plays a key role in the simulation performance of the VG model and its value. The parameter α and the parameter n of the VG model are stable parameters, which have less influence on the shape of the soil water characteristic curve. The parameter θr of the BC model is also a sensitive parameter, which has a significant influence on the shape of the soil water characteristic curve, while the parameter Φe of the BC model controls where the segmentation point of the BC model starts. The parameter Φe and the parameter λ of the Campbell model together control the shape of the soil water characteristic curve simulated by the Campbell model; (3) The error analysis of the model shows that the VG model has a better simulation performance under different soil texture and depth conditions, and the error of the measured 4-150 kPa soil matrix suction segment is limited to ±2.5%. The Campbell model has a strong fitting ability in the sandy loam area and the soil surface layer, while the BC model, due to its shape setting, often appears to be lower than the actual value in the middle section of the soil matrix potential and higher than the actual value in the high soil matrix potential section during the fitting process. In summary, the VG model has high applicability in the Naqu watershed of the Nujiang River source area, and it is recommended to use the VG model for fitting the soil water characteristic curve in the high altitude seasonal frozen zone . However, the model still has more obvious errors in the middle section of the soil matrix potential, and further work is still needed to prove its applicability to other alpine regions. Currently, there are still few studies on soil moisture profiles in the Tibetan Plateau, with scarce references and difficulties in field experiments. Therefore, in-situ observation experiments were chosen for data collection to obtain a long series of volumetric soil moisture content and soil matrix potential data, but soil moisture profiles are affected by wet and dry paths, and there are some errors in the soil moisture profiles. Therefore, it is necessary to analyze the paths of the collected data in the subsequent research and carry out validation experiments in the laboratory to improve and innovate the model to increase the simulation accuracy of the model, so as to make it more applicable in the Tibetan Plateau. This study can provide a basis for a deeper understanding of the soil moisture movement characteristics in the high altitude seasonal frozen zone and the water conservation role of the Chinese water tower zone.
Determining the soil water characteristic curve in the high altitude seasonal frozen zone is crucial to understand its soil water movement characteristics. However, today's research on modeling soil water characteristic curves in the high altitude seasonal frozen zones focuses more on the effects of permafrost, vegetation degradation, and other factors on the change of soil moisture content, and lacks the analysis of the applicability of soil water characteristic curves.The volumetric soil water content and soil matrix potential were measured by in-situ observation experiment, selected three models, Van Genuchten (VG), Brooks-Corey (BC), and Campbell for fitting, and analyzed the applicability of the soil water characteristic curve model in the Naqu watershed of the Nujiang River source area using the root-mean-square error and the coefficient of determination as the evaluation indexes. The results showed that: (1) The ERMS of the VG model was 66.6% and 56.9% lower than that of the BC and Campbell models, respectively, and the R2 of the VG model was higher than that of the BC and Campbell models (on average, 2.0% and 0.9% higher, respectively), and the VG model was considered sufficiently accurate as far as the R2 and the ERMS were concerned ( R2 > 0.97,ERMS ≤ 0.011cm3/cm3). While the BC model had an overall poor fitting effect, with an average R2 of 0.97 and an ERMS of 0.018cm3/cm3, the Campbell model had strong applicability in the soil surface layer, with an average R2 of 0.99 and an ERMS of 0.006cm3/cm3; (2) The parameter θr of the VG model plays a key role in the simulation performance of the VG model and its value. The parameter α and the parameter n of the VG model are stable parameters, which have less influence on the shape of the soil water characteristic curve. The parameter θr of the BC model is also a sensitive parameter, which has a significant influence on the shape of the soil water characteristic curve, while the parameter Φe of the BC model controls where the segmentation point of the BC model starts. The parameter Φe and the parameter λ of the Campbell model together control the shape of the soil water characteristic curve simulated by the Campbell model; (3) The error analysis of the model shows that the VG model has a better simulation performance under different soil texture and depth conditions, and the error of the measured 4-150 kPa soil matrix suction segment is limited to ±2.5%. The Campbell model has a strong fitting ability in the sandy loam area and the soil surface layer, while the BC model, due to its shape setting, often appears to be lower than the actual value in the middle section of the soil matrix potential and higher than the actual value in the high soil matrix potential section during the fitting process. In summary, the VG model has high applicability in the Naqu watershed of the Nujiang River source area, and it is recommended to use the VG model for fitting the soil water characteristic curve in the high altitude seasonal frozen zone . However, the model still has more obvious errors in the middle section of the soil matrix potential, and further work is still needed to prove its applicability to other alpine regions. Currently, there are still few studies on soil moisture profiles in the Tibetan Plateau, with scarce references and difficulties in field experiments. Therefore, in-situ observation experiments were chosen for data collection to obtain a long series of volumetric soil moisture content and soil matrix potential data, but soil moisture profiles are affected by wet and dry paths, and there are some errors in the soil moisture profiles. Therefore, it is necessary to analyze the paths of the collected data in the subsequent research and carry out validation experiments in the laboratory to improve and innovate the model to increase the simulation accuracy of the model, so as to make it more applicable in the Tibetan Plateau. This study can provide a basis for a deeper understanding of the soil moisture movement characteristics in the high altitude seasonal frozen zone and the water conservation role of the Chinese water tower zone.
2024, 22(2):258-264.
Abstract:
Multi-year regulation reservoirs are used to regulate the unbalanced water volume within and between years, and year-end water level control is linked to the overall benefits of the current year and the following several years. The water level at the end of the year is typically not fixed because of the unpredictability of natural inflow. It is worth studying how to optimize the year-end water level of multi-year regulation reservoirs based on the uncertainty of inflow to ensure their long-term comprehensive benefits.Taken the multi-year regulating Longyangxia Reservoir and Liujiaxia Rservoir in the upper reaches of the Yellow River as a case study, the year-end water level is optimized under uncertain inflow conditions. The Latin Hypercube Sampling-Monte Carlo (LHS-MC) method was applied to generate random reservoir inflows. On this basis, a multi-objective stochastic optimization model for cascade reservoirs considering the uncertain inflow was established. The best scheme from the Pareto solution set of the current-year power output and the year-end water level was obtained based on the TOPSIS decision-making method. The effects of runoff frequency and initial water level on year-end water level and power output were investigated, and the reliability of year-end expected water level on multi-year power output was verified.The results show that the initial water levels of Longyangxia Reservoir and Liujiaxia Reservoir are 2,590 m and 1,728 m, respectively, the total expected power output ranges from 9.514 billion kW?h to 9.689 billion kW?h, and the year-end water level of Longyangxia Reservoir ranges from 2,586.45 m to 2,587.41 m. The higher the year-end water level, the less power is generated. The water level of Longyangxia Reservoir and the power generation of the cascade reservoirs differ greatly from June to October under different inflow frequencies. The lower the frequency of runoff and the higher the initial water level of Longyangxia Reservoir, the higher the year-end water level of Longyangxia and the higher the power output of Longyangxia Reservoir and Liujiaxia Reservoirs. The optimal year-end water level of Longyangxia Reservoir should be controlled between 2,580 m and 2,590 m based on the stochastic optimization model, which is a significant reduction from the actual operation. When the optimal year-end expected water level obtained by stochastic optimization is used to control Longyangxia Reservoir, the reliability of guaranteeing the power output benefit is above 98%.Overall, under the uncertainty inflow scenarios, there is a competitive relationship between the annual estimated power output of Longyangxia Reservoir and Liujiaxia Reservoir and the year-end expected water level of Longyangxia Reservoir. The main determinants of Longyangxia Reservoir's year-end water level are the reservoir's inflow frequency and initial water level. This approach has a high degree of reliability and significantly narrows the range of year-end water level under the existing dispatching mechanism.
Multi-year regulation reservoirs are used to regulate the unbalanced water volume within and between years, and year-end water level control is linked to the overall benefits of the current year and the following several years. The water level at the end of the year is typically not fixed because of the unpredictability of natural inflow. It is worth studying how to optimize the year-end water level of multi-year regulation reservoirs based on the uncertainty of inflow to ensure their long-term comprehensive benefits.Taken the multi-year regulating Longyangxia Reservoir and Liujiaxia Rservoir in the upper reaches of the Yellow River as a case study, the year-end water level is optimized under uncertain inflow conditions. The Latin Hypercube Sampling-Monte Carlo (LHS-MC) method was applied to generate random reservoir inflows. On this basis, a multi-objective stochastic optimization model for cascade reservoirs considering the uncertain inflow was established. The best scheme from the Pareto solution set of the current-year power output and the year-end water level was obtained based on the TOPSIS decision-making method. The effects of runoff frequency and initial water level on year-end water level and power output were investigated, and the reliability of year-end expected water level on multi-year power output was verified.The results show that the initial water levels of Longyangxia Reservoir and Liujiaxia Reservoir are 2,590 m and 1,728 m, respectively, the total expected power output ranges from 9.514 billion kW?h to 9.689 billion kW?h, and the year-end water level of Longyangxia Reservoir ranges from 2,586.45 m to 2,587.41 m. The higher the year-end water level, the less power is generated. The water level of Longyangxia Reservoir and the power generation of the cascade reservoirs differ greatly from June to October under different inflow frequencies. The lower the frequency of runoff and the higher the initial water level of Longyangxia Reservoir, the higher the year-end water level of Longyangxia and the higher the power output of Longyangxia Reservoir and Liujiaxia Reservoirs. The optimal year-end water level of Longyangxia Reservoir should be controlled between 2,580 m and 2,590 m based on the stochastic optimization model, which is a significant reduction from the actual operation. When the optimal year-end expected water level obtained by stochastic optimization is used to control Longyangxia Reservoir, the reliability of guaranteeing the power output benefit is above 98%.Overall, under the uncertainty inflow scenarios, there is a competitive relationship between the annual estimated power output of Longyangxia Reservoir and Liujiaxia Reservoir and the year-end expected water level of Longyangxia Reservoir. The main determinants of Longyangxia Reservoir's year-end water level are the reservoir's inflow frequency and initial water level. This approach has a high degree of reliability and significantly narrows the range of year-end water level under the existing dispatching mechanism.
2024, 22(2):265-271.
Abstract:
Dynamic monitoring of soil moisture is of great significance for guiding timely and appropriate agricultural irrigation. Currently, the water content measurement instruments used in domestic field experiments are mainly imported from instrument companies in Australia, the Netherlands, and other countries. However, these instruments do not open the bottom-level sensor calibration program to ordinary users, resulting in significant differences in water monitoring accuracy when used in different soil types. Frequency domain reflectometry (FDR) is the most widely used soil moisture measurement method in China. In response to the monitoring needs of soil moisture in agricultural irrigation fields, a ring-shaped soil moisture sensor based on the FDR method was designed and developed. The function relationship between soil volume moisture content and FDR sensor circuit oscillation frequency was established by preparing standard soil samples in the laboratory, and the accuracy of the sensor was verified through field measurement data. Seven treatments were set up in the indoor experiment, with soil volume moisture content of 13.21%, 16.28%, 20.46%, 27.45%, 31.20%, 34.54%, and 39.80%, respectively. FDR sensors were installed at two depths of 5 cm and 15 cm from the soil surface, and the oscillation frequency SF of the sensor and the soil volume moisture content θv obtained by the drying method were fitted using the exponential function relationship θV=aSBF to determine the coefficients a and b corresponding to the sensor oscillation circuit. The field validation experiment was conducted at the irrigation test station in Baoding. FDR sensors were buried at depths of 15 cm and 60 cm in the irrigation district for soil moisture observation, and conventional observations were conducted using the soil drying method at the same time. The laboratory calibration results showed that at a depth of 15 cm, the fit between the oscillation frequency SF and the soil volume moisture content θv was good, and the R2 value of the fitting curve was 0.876 4. In contrast, at a depth of 5 cm, the data measurement was unstable due to the small distance between the FDR sensor and the soil surface, and the electromagnetic wave was interfered with by the surface air, resulting in slightly worse fitting results. The field validation experiment results showed that the FDR soil moisture sensor calibrated with a and b coefficients prepared in the laboratory with soil samples can accurately reflect the actual soil moisture content ranging from the crop wilting coefficient to the soil saturation moisture content, and can be used for guidance of precision irrigation. In response to the needs of agricultural irrigation, a ring-shaped soil moisture sensor based on the FDR principle was developed, and its accuracy was tested in the laboratory and field. The laboratory soil column test of the sensor found that the accuracy of the sensor is affected by the burial depth in the soil. When the burial depth of the sensor is 15 cm from the soil sample surface, the R2 value of the fitting curve between the FDR sensor measurement data and the volume moisture content obtained by the drying method is 0.876 4, and the fitting effect is better. At a depth of 5 cm from the soil sample surface, the fitting curve effect between FDR data and drying method data is not ideal, mainly because the FDR sensor is too close to the soil surface, and the electromagnetic wave is interfered with by the surface air, resulting in unstable data measurement. To ensure the reliability of the data, it is recommended that the ring-shaped soil moisture sensor be used for soil moisture monitoring below 15 cm from the soil surface in practical applications. Field calibration is usually more cumbersome than laboratory calibration, and requires much more time than laboratory calibration. The FDR sensor developed is calibrated with soil samples prepared from the field measurement area, and its observed soil volume moisture content and the error range of the soil drying method are [0.5%, 1.1%], which meets the accuracy requirements of the "Automatic Soil Moisture Observation Instrument" (QX/T 567-2020). Therefore, the method of laboratory calibration by taking soil samples in the measurement field can be used to improve the calibration efficiency.
Dynamic monitoring of soil moisture is of great significance for guiding timely and appropriate agricultural irrigation. Currently, the water content measurement instruments used in domestic field experiments are mainly imported from instrument companies in Australia, the Netherlands, and other countries. However, these instruments do not open the bottom-level sensor calibration program to ordinary users, resulting in significant differences in water monitoring accuracy when used in different soil types. Frequency domain reflectometry (FDR) is the most widely used soil moisture measurement method in China. In response to the monitoring needs of soil moisture in agricultural irrigation fields, a ring-shaped soil moisture sensor based on the FDR method was designed and developed. The function relationship between soil volume moisture content and FDR sensor circuit oscillation frequency was established by preparing standard soil samples in the laboratory, and the accuracy of the sensor was verified through field measurement data. Seven treatments were set up in the indoor experiment, with soil volume moisture content of 13.21%, 16.28%, 20.46%, 27.45%, 31.20%, 34.54%, and 39.80%, respectively. FDR sensors were installed at two depths of 5 cm and 15 cm from the soil surface, and the oscillation frequency SF of the sensor and the soil volume moisture content θv obtained by the drying method were fitted using the exponential function relationship θV=aSBF to determine the coefficients a and b corresponding to the sensor oscillation circuit. The field validation experiment was conducted at the irrigation test station in Baoding. FDR sensors were buried at depths of 15 cm and 60 cm in the irrigation district for soil moisture observation, and conventional observations were conducted using the soil drying method at the same time. The laboratory calibration results showed that at a depth of 15 cm, the fit between the oscillation frequency SF and the soil volume moisture content θv was good, and the R2 value of the fitting curve was 0.876 4. In contrast, at a depth of 5 cm, the data measurement was unstable due to the small distance between the FDR sensor and the soil surface, and the electromagnetic wave was interfered with by the surface air, resulting in slightly worse fitting results. The field validation experiment results showed that the FDR soil moisture sensor calibrated with a and b coefficients prepared in the laboratory with soil samples can accurately reflect the actual soil moisture content ranging from the crop wilting coefficient to the soil saturation moisture content, and can be used for guidance of precision irrigation. In response to the needs of agricultural irrigation, a ring-shaped soil moisture sensor based on the FDR principle was developed, and its accuracy was tested in the laboratory and field. The laboratory soil column test of the sensor found that the accuracy of the sensor is affected by the burial depth in the soil. When the burial depth of the sensor is 15 cm from the soil sample surface, the R2 value of the fitting curve between the FDR sensor measurement data and the volume moisture content obtained by the drying method is 0.876 4, and the fitting effect is better. At a depth of 5 cm from the soil sample surface, the fitting curve effect between FDR data and drying method data is not ideal, mainly because the FDR sensor is too close to the soil surface, and the electromagnetic wave is interfered with by the surface air, resulting in unstable data measurement. To ensure the reliability of the data, it is recommended that the ring-shaped soil moisture sensor be used for soil moisture monitoring below 15 cm from the soil surface in practical applications. Field calibration is usually more cumbersome than laboratory calibration, and requires much more time than laboratory calibration. The FDR sensor developed is calibrated with soil samples prepared from the field measurement area, and its observed soil volume moisture content and the error range of the soil drying method are [0.5%, 1.1%], which meets the accuracy requirements of the "Automatic Soil Moisture Observation Instrument" (QX/T 567-2020). Therefore, the method of laboratory calibration by taking soil samples in the measurement field can be used to improve the calibration efficiency.
ZHUANG?Junyi
,
，CHENG?Yizhi
，HOU?Yizhe
，LIU?Yulan
，WANG?Kai
,
，CHENG?Lirong
,
，
DING?Aizhong
,
，JI?Zhihui
，XU?Wei
，WANG?Chenggang
2024, 22(2):272-281.
Abstract:
Hexavalent chromium Cr(VI) is a heavy metal pollutant that has attracted much attention. Due to its strong mobility, the impact of Cr(VI) contaminated soil on groundwater is one of the key issues that need to be solved in the field of soil-water synergistic remediation. At present, soil pollution and groundwater pollution remediation are still considered separately in the remediation project of chromium-contaminated sites. Research of the target values of soil and groundwater remediation lacks correlations. Few studies focused on the correlation between soil remediation targets and groundwater remediation targets. Due to the complexity and heterogeneity of the site environment and the reactivity of pollutants, the release and transformation of residual and fixed Cr(VI) in the soil making the remediation of chromium-contaminated sites remains challenging.The contaminated soil of the original Changsha Chromium Salt Plant was taken as the research object, and the dynamic leaching test was used to study the leaching characteristics of soil Cr(VI) and its influence on groundwater under different leaching modes. Seven soil columns were set up to simulate the migration of Cr(VI) in contaminated soil in the vadose zone and saturated zone. For the vadose zone scenario, pure water was used for soil column leaching to study the migration and release of Cr(VI) in the soil. The saturated zone scenario was designed with continuous and intermittent leaching conditions (leaching for 12 h, suspension for 12 h) to simulate the pumping remediation scenario of contaminated groundwater, and to study the remediation effect of different leaching modes on contaminated groundwater. The model of Cr(VI) migration and transformation in the experiment was constructed by COMSOL Multiphysics ? 5.6, and the concentration change and cumulative leaching quality of Cr(VI) in six different scenarios under continuous and intermittent leaching modes were calculated.The results showed that the leaching flow rate would affect the time required for Cr(VI) to reach desorption stability in the soil column. For continuous leaching mode, the time to reach equilibrium at high, medium, and low flow rates was 1 d, 4 d, and 15 d, respectively. The leaching efficiency of Cr(VI) in intermittent leaching mode was slightly lower than that in continuous leaching mode, which was mainly controlled by the renewal efficiency of pore water in soil. Experimental calculation results showed that the leaching rate of Cr(VI) increased with the increase of flow rate under the same mode. Complex reactions happened during the intermittent leaching mode process, which may affect the final cumulative leaching mass. According to the calculation, the minimum leaching percentage was 33.67 % under the high flow rate scenario of the intermittent leaching column in the same period, and the maximum leaching percentage was 83.99 % under the high flow rate scenario of the continuous leaching column. Combined with the results of model calculation and column experiment, it was found that the leachate mass concentration of Cr(VI) reached the Class V water standard of groundwater ( > 0.1 mg/L ), even though the soil reached the screening value of Class II land use (5.7 mg/kg ). The model predicted the number of days required for different simulated columns. The days required for the 2-1, 2-2, 3-1, and 3-2 simulated columns leaching solutions to reach the Class IV groundwater standard were 270, 230, 265, and 293 days, respectively.The main conclusions are as follow : (1) The groundwater flow rate affects the time required for chromium to reach desorption equilibrium in the soil column. The influence of different leaching modes is limited. For the continuous column, under a greater flow rate, the column will reach the desorption equilibrium faster. The leaching efficiency of Cr(VI) in intermittent mode was slightly worse than that in continuous pumping mode, which was mainly controlled by the renewal efficiency of pore water in soil. (2) The cumulative leaching quality of Cr(VI) in continuous column was greater than that in intermittent column. In the same mode, the greater the leaching rate, the greater the cumulative leaching quality of Cr(VI). (3) A one-dimensional model of Cr(VI) migration and transformation was constructed using COMSOL Multiphysics ? 5.6. After verification, it was found by calculation that the intermittent leaching model can repair Cr(VI) contaminated soil more efficiently. (4) Through the model calculation, it is found that there are differences between the existing soil remediation targets and the soil remediation targets for protecting the groundwater environment. When the mass concentration of Cr(VI) in the soil medium reached the screening value of the second-class land, the content of Cr(VI) in the leachate reached the V-class water standard, which still posed a threat to the groundwater environment.According to the results, it is found that chromium-contaminated soil can release pollutants into groundwater for a long time. Therefore, it's necessary to increase the verification steps of pollutant release in the soil at different remediation stages to ensure that the soil remediation goal of protecting the groundwater environment is achieved. For the remediation of saturated zones, based on the characteristics of different water-bearing media, the pumping remediation technology should be combined with other technologies according to the different release stages of pollutants, to achieve the goal of water and soil co-governance by efficient and economical means.
Hexavalent chromium Cr(VI) is a heavy metal pollutant that has attracted much attention. Due to its strong mobility, the impact of Cr(VI) contaminated soil on groundwater is one of the key issues that need to be solved in the field of soil-water synergistic remediation. At present, soil pollution and groundwater pollution remediation are still considered separately in the remediation project of chromium-contaminated sites. Research of the target values of soil and groundwater remediation lacks correlations. Few studies focused on the correlation between soil remediation targets and groundwater remediation targets. Due to the complexity and heterogeneity of the site environment and the reactivity of pollutants, the release and transformation of residual and fixed Cr(VI) in the soil making the remediation of chromium-contaminated sites remains challenging.The contaminated soil of the original Changsha Chromium Salt Plant was taken as the research object, and the dynamic leaching test was used to study the leaching characteristics of soil Cr(VI) and its influence on groundwater under different leaching modes. Seven soil columns were set up to simulate the migration of Cr(VI) in contaminated soil in the vadose zone and saturated zone. For the vadose zone scenario, pure water was used for soil column leaching to study the migration and release of Cr(VI) in the soil. The saturated zone scenario was designed with continuous and intermittent leaching conditions (leaching for 12 h, suspension for 12 h) to simulate the pumping remediation scenario of contaminated groundwater, and to study the remediation effect of different leaching modes on contaminated groundwater. The model of Cr(VI) migration and transformation in the experiment was constructed by COMSOL Multiphysics ? 5.6, and the concentration change and cumulative leaching quality of Cr(VI) in six different scenarios under continuous and intermittent leaching modes were calculated.The results showed that the leaching flow rate would affect the time required for Cr(VI) to reach desorption stability in the soil column. For continuous leaching mode, the time to reach equilibrium at high, medium, and low flow rates was 1 d, 4 d, and 15 d, respectively. The leaching efficiency of Cr(VI) in intermittent leaching mode was slightly lower than that in continuous leaching mode, which was mainly controlled by the renewal efficiency of pore water in soil. Experimental calculation results showed that the leaching rate of Cr(VI) increased with the increase of flow rate under the same mode. Complex reactions happened during the intermittent leaching mode process, which may affect the final cumulative leaching mass. According to the calculation, the minimum leaching percentage was 33.67 % under the high flow rate scenario of the intermittent leaching column in the same period, and the maximum leaching percentage was 83.99 % under the high flow rate scenario of the continuous leaching column. Combined with the results of model calculation and column experiment, it was found that the leachate mass concentration of Cr(VI) reached the Class V water standard of groundwater ( > 0.1 mg/L ), even though the soil reached the screening value of Class II land use (5.7 mg/kg ). The model predicted the number of days required for different simulated columns. The days required for the 2-1, 2-2, 3-1, and 3-2 simulated columns leaching solutions to reach the Class IV groundwater standard were 270, 230, 265, and 293 days, respectively.The main conclusions are as follow : (1) The groundwater flow rate affects the time required for chromium to reach desorption equilibrium in the soil column. The influence of different leaching modes is limited. For the continuous column, under a greater flow rate, the column will reach the desorption equilibrium faster. The leaching efficiency of Cr(VI) in intermittent mode was slightly worse than that in continuous pumping mode, which was mainly controlled by the renewal efficiency of pore water in soil. (2) The cumulative leaching quality of Cr(VI) in continuous column was greater than that in intermittent column. In the same mode, the greater the leaching rate, the greater the cumulative leaching quality of Cr(VI). (3) A one-dimensional model of Cr(VI) migration and transformation was constructed using COMSOL Multiphysics ? 5.6. After verification, it was found by calculation that the intermittent leaching model can repair Cr(VI) contaminated soil more efficiently. (4) Through the model calculation, it is found that there are differences between the existing soil remediation targets and the soil remediation targets for protecting the groundwater environment. When the mass concentration of Cr(VI) in the soil medium reached the screening value of the second-class land, the content of Cr(VI) in the leachate reached the V-class water standard, which still posed a threat to the groundwater environment.According to the results, it is found that chromium-contaminated soil can release pollutants into groundwater for a long time. Therefore, it's necessary to increase the verification steps of pollutant release in the soil at different remediation stages to ensure that the soil remediation goal of protecting the groundwater environment is achieved. For the remediation of saturated zones, based on the characteristics of different water-bearing media, the pumping remediation technology should be combined with other technologies according to the different release stages of pollutants, to achieve the goal of water and soil co-governance by efficient and economical means.
2024, 22(2):282-290.
Abstract:
People's development and utilization of the river are increasing because of power generation, navigation, and irrigation, at the same time, the hydrological regime of the river and the ecological environment has also caused a certain impact. When evaluating the changing characteristics of river hydrological alterations, utilizing the ecohydrological index system is often necessary to quantify the degree of river hydrological changes. Due to the large differences in climatic conditions, geomorphological features, and hydrological-ecological response relationships in different study areas, problems of correlation between indicators and data redundancy in the traditional hydrological alteration index method (IHA) may cause the overall evaluation bias.The evaluation of the hydrological regime of the river in the lower reaches of the Hanjiang River was carried out considering the influence of the average daily flow, the shape of the river cross-section, and water intake and diversion projects of the main and tributary streams in the Hanjiang River basin. For this purpose, three hydrological stations on the main river basin of the Hanjiang River and three hydrological stations in its tributary basins were selected, and the IHA indexes of the six hydrological stations in the basin were optimized by the principal component analysis method, and then further screened based on the results of the correlation test method.The results showed that: Thirteen representative indicators were February flow, April flow, July flow, October flow, December flow, base flow index, lowest flow occurrence date, highest flow occurrence date, number of low-flow pulses, high flow duration, average daily flow increase rate, average daily flow reduction rate and reversal numbers. The correlation test analysis showed that the correlation of the thirteen representative indicators of the six hydrological stations was greatly reduced, and the correlation coefficients between 70% of representative indicators did not exceed 0.3. The difference between IHA indicators and the representative indicators on the overall hydrological alteration degree of the lower Hanjiang River basin was less than 7.5 percentage points verified by the RVA method.Considering the different hydrological situations of the rivers in the mainstream and tributary basins of the lower reaches of Hanjiang River basin, different hydrological stations are optimized for representative indicators, which can evaluate the hydrological situation of the entire lower reaches of Hanjiang River basin. The representative indicators can provide a more comprehensive and reasonable evaluation of the hydrological regime of the entire lower reaches of Hanjiang River basin, which is convenient for evaluating the degree of impacts of human activities on the river promptly.
People's development and utilization of the river are increasing because of power generation, navigation, and irrigation, at the same time, the hydrological regime of the river and the ecological environment has also caused a certain impact. When evaluating the changing characteristics of river hydrological alterations, utilizing the ecohydrological index system is often necessary to quantify the degree of river hydrological changes. Due to the large differences in climatic conditions, geomorphological features, and hydrological-ecological response relationships in different study areas, problems of correlation between indicators and data redundancy in the traditional hydrological alteration index method (IHA) may cause the overall evaluation bias.The evaluation of the hydrological regime of the river in the lower reaches of the Hanjiang River was carried out considering the influence of the average daily flow, the shape of the river cross-section, and water intake and diversion projects of the main and tributary streams in the Hanjiang River basin. For this purpose, three hydrological stations on the main river basin of the Hanjiang River and three hydrological stations in its tributary basins were selected, and the IHA indexes of the six hydrological stations in the basin were optimized by the principal component analysis method, and then further screened based on the results of the correlation test method.The results showed that: Thirteen representative indicators were February flow, April flow, July flow, October flow, December flow, base flow index, lowest flow occurrence date, highest flow occurrence date, number of low-flow pulses, high flow duration, average daily flow increase rate, average daily flow reduction rate and reversal numbers. The correlation test analysis showed that the correlation of the thirteen representative indicators of the six hydrological stations was greatly reduced, and the correlation coefficients between 70% of representative indicators did not exceed 0.3. The difference between IHA indicators and the representative indicators on the overall hydrological alteration degree of the lower Hanjiang River basin was less than 7.5 percentage points verified by the RVA method.Considering the different hydrological situations of the rivers in the mainstream and tributary basins of the lower reaches of Hanjiang River basin, different hydrological stations are optimized for representative indicators, which can evaluate the hydrological situation of the entire lower reaches of Hanjiang River basin. The representative indicators can provide a more comprehensive and reasonable evaluation of the hydrological regime of the entire lower reaches of Hanjiang River basin, which is convenient for evaluating the degree of impacts of human activities on the river promptly.
2024, 22(2):291-298.
Abstract:
The Henan section of the Yangtze-to-Huaihe River Water Diversion Project is listed as one of the ten major water conservancy projects. The main functions are urban and rural water supply and improvement of water ecological environment. The water diversion volume of the project is 500 million m3 in 2030 and 634 million m3 in 2040. The Henan section is mainly composed of two open channels, four storage reservoirs, and three water pipelines. Although the risk of sudden water pollution incidents in four storage reservoirs and three water pipelines is very small, the transportation industry along the two open channels (i.e., Qingshui River section and Luxin Canal section) is developed and there are many cross buildings, which are prone to sudden water pollution incidents. Once a water pollution incident occurs, it will have a huge impact on drinking water security, industrial water security, and the ecological environment security of the residents in the water receiving area. Therefore, it is of great significance to carry out the risk analysis of sudden water pollution incidents to give full play to the comprehensive benefits of the project, ensure the safety of water supply in the water receiving area, and maintain a good water ecological environment.The risk factors of sudden water pollution incidents in the Henan section were identified based on an investigation of the existing research results of risk analysis and control countermeasures of sudden water pollution incidents in water transfer projects, and an adaptive risk assessment index system was established. The classification criteria and risk level evaluation model comprehensively evaluated the risk levels of sudden water pollution incidents in seven evaluation sections, and risk monitoring and risk control measures for sudden water pollution incidents were proposed.The results showed that: (1) The risk sources of sudden water pollution incidents in the Henan section are road traffic accident risk, sewage discharge risk and other risks. (2) Except that the risk level of sudden water pollution incidents in the Qingshui River section and its sub-reaches from the Shiliang controlling gate to the Houheya controlling gate is significant (grade Ⅱ), the risk level of sudden water pollution incidents in the other five evaluation reaches is large (grade Ⅲ). (3) To reduce the risk of sudden water pollution incidents in the Henan section, it is necessary to further reduce the risk of risk sources and improve the effectiveness of risk control.Support is provided for reducing the occurrence probability and harm degree of sudden water pollution incidents in the Henan section of the Yangtze-to-Huaihe River Water Diversion Project, and is of great significance for giving full play to the comprehensive benefits of the project, ensuring the safety of water supply in the water-receiving area, and maintaining a good water ecological environment.
The Henan section of the Yangtze-to-Huaihe River Water Diversion Project is listed as one of the ten major water conservancy projects. The main functions are urban and rural water supply and improvement of water ecological environment. The water diversion volume of the project is 500 million m3 in 2030 and 634 million m3 in 2040. The Henan section is mainly composed of two open channels, four storage reservoirs, and three water pipelines. Although the risk of sudden water pollution incidents in four storage reservoirs and three water pipelines is very small, the transportation industry along the two open channels (i.e., Qingshui River section and Luxin Canal section) is developed and there are many cross buildings, which are prone to sudden water pollution incidents. Once a water pollution incident occurs, it will have a huge impact on drinking water security, industrial water security, and the ecological environment security of the residents in the water receiving area. Therefore, it is of great significance to carry out the risk analysis of sudden water pollution incidents to give full play to the comprehensive benefits of the project, ensure the safety of water supply in the water receiving area, and maintain a good water ecological environment.The risk factors of sudden water pollution incidents in the Henan section were identified based on an investigation of the existing research results of risk analysis and control countermeasures of sudden water pollution incidents in water transfer projects, and an adaptive risk assessment index system was established. The classification criteria and risk level evaluation model comprehensively evaluated the risk levels of sudden water pollution incidents in seven evaluation sections, and risk monitoring and risk control measures for sudden water pollution incidents were proposed.The results showed that: (1) The risk sources of sudden water pollution incidents in the Henan section are road traffic accident risk, sewage discharge risk and other risks. (2) Except that the risk level of sudden water pollution incidents in the Qingshui River section and its sub-reaches from the Shiliang controlling gate to the Houheya controlling gate is significant (grade Ⅱ), the risk level of sudden water pollution incidents in the other five evaluation reaches is large (grade Ⅲ). (3) To reduce the risk of sudden water pollution incidents in the Henan section, it is necessary to further reduce the risk of risk sources and improve the effectiveness of risk control.Support is provided for reducing the occurrence probability and harm degree of sudden water pollution incidents in the Henan section of the Yangtze-to-Huaihe River Water Diversion Project, and is of great significance for giving full play to the comprehensive benefits of the project, ensuring the safety of water supply in the water-receiving area, and maintaining a good water ecological environment.
2024, 22(2):299-308.
Abstract:
Huangcaoweis are national-level storage and detention zones in the Chu River basin. The two regions serve a dual function for flood control by retaining excess water and ensuring the survival and development of local residents by water supply. The reality of a growing population and limited land has given rise to a multifaceted role for flood storage areas in China, encompassing flood control and development. In addition, the flood storage area also possesses ecological functions such as climate regulation, which bestows unique ecological service functions and economic value. Therefore, we should correctly deal with the relationship between flood control, development and ecological environmental protection in these regions, maintain and maximize the functions and benefits of the flood storage area, putting flood storage areas on a gradual path to sustainable use.Taking these two flood storage areas as case studies, an assessment of their ecological service value is conducted, mainly including values of climate regulation, water purification, air purification, soil conservation, carbon fixation, biodiversity and scientific research and education. Various accounting methods, including the alternative cost method and outcome parameter method, are applied to evaluate the value of each service. Accurate quantification of the ecosystem's service value facilitates the integration of ecological benefits into the economic and social development evaluation system. On the basis of calculating the value of regional ecosystem services, evaluation indicators are constructed for the sustainable development of flood storage and detention areas from three aspects: flood prevention, economic and ecological functions. The sustainable development level of flood storage and detention areas are evaluated by AHP-fuzzy comprehensive evaluation method, incorporating weights assigned by the AHP method and comprehensive evaluation is made by fuzzy comprehensive evaluation method. According to the evaluation results, the relationship between flood control, economy and ecology is coordinated to maximize the comprehensive benefits of various functions of the flood storage area and realize the sustainable development of the flood storage area.Meanwhile, scenario analysis and development prediction for the future state of the flood storage area are carried out to provide a reference for the quantitative evaluation of ecological benefits and sustainable development of the flood storage area. The results show that the sustainable development level of the Huangcaoweis are general, which basically accords with the development pattern in the polder area. A reduction in the ecological function of farmland and wetlands at the current stage of flood storage area development would lower its sustainability. Conversely, if the flood storage area shifts toward farmland ecological transformation and expansion of wetland areas, its sustainable development level could surpass the current stage.Finally, the challenges encountered during the sustainable development process are addresses in the two flood storage areas and proposes corresponding suggestions and countermeasures. To alleviate issues related to regional water withdrawal challenges, it is recommended to expedite water withdrawal through drainage ditch dredging and drainage station construction. For this kind of flood storage area where agricultural development takes precedence, adjustments to the crop planting structure are suggested, planting crops with high economic value and good water resistance to optimize and adjust the land use mode in the flood storage area, and to reduce the flood disaster losses. Leveraging the region's advantages, an emphasis on ecological farming is encouraged to establish a distinctive farming model. Developing ecological wetlands and agricultural sightseeing projects according to local conditions, the region's vital ecological role can be maximized, and striving to achieve sustainable development of the region.
Huangcaoweis are national-level storage and detention zones in the Chu River basin. The two regions serve a dual function for flood control by retaining excess water and ensuring the survival and development of local residents by water supply. The reality of a growing population and limited land has given rise to a multifaceted role for flood storage areas in China, encompassing flood control and development. In addition, the flood storage area also possesses ecological functions such as climate regulation, which bestows unique ecological service functions and economic value. Therefore, we should correctly deal with the relationship between flood control, development and ecological environmental protection in these regions, maintain and maximize the functions and benefits of the flood storage area, putting flood storage areas on a gradual path to sustainable use.Taking these two flood storage areas as case studies, an assessment of their ecological service value is conducted, mainly including values of climate regulation, water purification, air purification, soil conservation, carbon fixation, biodiversity and scientific research and education. Various accounting methods, including the alternative cost method and outcome parameter method, are applied to evaluate the value of each service. Accurate quantification of the ecosystem's service value facilitates the integration of ecological benefits into the economic and social development evaluation system. On the basis of calculating the value of regional ecosystem services, evaluation indicators are constructed for the sustainable development of flood storage and detention areas from three aspects: flood prevention, economic and ecological functions. The sustainable development level of flood storage and detention areas are evaluated by AHP-fuzzy comprehensive evaluation method, incorporating weights assigned by the AHP method and comprehensive evaluation is made by fuzzy comprehensive evaluation method. According to the evaluation results, the relationship between flood control, economy and ecology is coordinated to maximize the comprehensive benefits of various functions of the flood storage area and realize the sustainable development of the flood storage area.Meanwhile, scenario analysis and development prediction for the future state of the flood storage area are carried out to provide a reference for the quantitative evaluation of ecological benefits and sustainable development of the flood storage area. The results show that the sustainable development level of the Huangcaoweis are general, which basically accords with the development pattern in the polder area. A reduction in the ecological function of farmland and wetlands at the current stage of flood storage area development would lower its sustainability. Conversely, if the flood storage area shifts toward farmland ecological transformation and expansion of wetland areas, its sustainable development level could surpass the current stage.Finally, the challenges encountered during the sustainable development process are addresses in the two flood storage areas and proposes corresponding suggestions and countermeasures. To alleviate issues related to regional water withdrawal challenges, it is recommended to expedite water withdrawal through drainage ditch dredging and drainage station construction. For this kind of flood storage area where agricultural development takes precedence, adjustments to the crop planting structure are suggested, planting crops with high economic value and good water resistance to optimize and adjust the land use mode in the flood storage area, and to reduce the flood disaster losses. Leveraging the region's advantages, an emphasis on ecological farming is encouraged to establish a distinctive farming model. Developing ecological wetlands and agricultural sightseeing projects according to local conditions, the region's vital ecological role can be maximized, and striving to achieve sustainable development of the region.
12 Hourly scale real-time flood forecasting in the Three Gorges Reservoir basin based on the VIC model
2024, 22(2):309-318.
Abstract:
The existing basin real-time flood forecasting system is based on the lumped model. With the increasing demand for spatial and temporal refinement of flood forecasting in large-scale basin flood control, the lumped model cannot adequately consider the unevenness of rainfall and spatial and temporal distribution of subsurface, and it is difficult to apply it to the current large-scale basin real-time flood forecasting. With the wide application of remote sensing and geographic information technology in the field of hydrology, the source of rainfall and subsurface data acquisition and data accuracy has been greatly improved, so the distributed hydrological model has gradually developed into a research hotspot in the field of hydrological modeling. However, due to the limitation of the accuracy of rainfall, runoff, and subsurface data, the application of distributed hydrological models in the field of real-time flood forecasting, especially in hourly scale forecasting, is still relatively small, and the forecast accuracy needs to be improved. With the abundant and accumulated information from satellite telemetry and ground observation sites in the basin, the hydrological and subsurface information can meet the demand for hourly flood forecast modeling by distributed hydrological models.Taken the Three Gorges Reservoir basin as an example, the process of real-time flood forecasting by the VIC model is carried out. The process of real-time rolling flood forecasting by the VIC model is divided into three parts: data access, model operation, and result output. To address the problem the original unit line routing method of the VIC model has a daily time scale and can not be used for hourly scale real-time flood forecasting. The slope routing is carried out using the slope unit line based on Gamma distribution, the river network routing is carried out using the IRF-UH method, and the hourly-scale VIC distributed flood forecasting model is established. The real-time rolling flood forecasting scheme is constructed, and the VIC distributed flood forecasting model is deployed, and applied to the reservoir area in 2022 for real-time flood forecasting.The results show that the average passing rate of flood volume and flood peak in the four sub-basins of the Three Gorges Reservoir area during the regular and validation periods is above 80%, and the average value of the coefficient of certainty is above 0.70. The VIC model shows good applicability in hourly-scale flood forecasting. It achieves good results in the real-time flood forecasting of four typical floods in the Three Gorges Reservoir area in 2022 and 2023, and can accurately grasp the flood volume and incoming water process in the key flow-producing areas of the reservoir area. The VIC hourly scale model is therefore a useful tool in the Three Gorges Reservoir area.Therefore, the VIC hourly scale model shows good performance in real-time flood forecasting in the Three Gorges Reservoir area and has great potential to be applied in real-time flood forecasting in large-scale basins. Since there are many small and medium-sized reservoirs in the Three Gorges Reservoir area, the model structure can be further improved and enriched at a later stage to further enhance the accuracy of the real-time flood forecasting system by considering the influence of human activities.
The existing basin real-time flood forecasting system is based on the lumped model. With the increasing demand for spatial and temporal refinement of flood forecasting in large-scale basin flood control, the lumped model cannot adequately consider the unevenness of rainfall and spatial and temporal distribution of subsurface, and it is difficult to apply it to the current large-scale basin real-time flood forecasting. With the wide application of remote sensing and geographic information technology in the field of hydrology, the source of rainfall and subsurface data acquisition and data accuracy has been greatly improved, so the distributed hydrological model has gradually developed into a research hotspot in the field of hydrological modeling. However, due to the limitation of the accuracy of rainfall, runoff, and subsurface data, the application of distributed hydrological models in the field of real-time flood forecasting, especially in hourly scale forecasting, is still relatively small, and the forecast accuracy needs to be improved. With the abundant and accumulated information from satellite telemetry and ground observation sites in the basin, the hydrological and subsurface information can meet the demand for hourly flood forecast modeling by distributed hydrological models.Taken the Three Gorges Reservoir basin as an example, the process of real-time flood forecasting by the VIC model is carried out. The process of real-time rolling flood forecasting by the VIC model is divided into three parts: data access, model operation, and result output. To address the problem the original unit line routing method of the VIC model has a daily time scale and can not be used for hourly scale real-time flood forecasting. The slope routing is carried out using the slope unit line based on Gamma distribution, the river network routing is carried out using the IRF-UH method, and the hourly-scale VIC distributed flood forecasting model is established. The real-time rolling flood forecasting scheme is constructed, and the VIC distributed flood forecasting model is deployed, and applied to the reservoir area in 2022 for real-time flood forecasting.The results show that the average passing rate of flood volume and flood peak in the four sub-basins of the Three Gorges Reservoir area during the regular and validation periods is above 80%, and the average value of the coefficient of certainty is above 0.70. The VIC model shows good applicability in hourly-scale flood forecasting. It achieves good results in the real-time flood forecasting of four typical floods in the Three Gorges Reservoir area in 2022 and 2023, and can accurately grasp the flood volume and incoming water process in the key flow-producing areas of the reservoir area. The VIC hourly scale model is therefore a useful tool in the Three Gorges Reservoir area.Therefore, the VIC hourly scale model shows good performance in real-time flood forecasting in the Three Gorges Reservoir area and has great potential to be applied in real-time flood forecasting in large-scale basins. Since there are many small and medium-sized reservoirs in the Three Gorges Reservoir area, the model structure can be further improved and enriched at a later stage to further enhance the accuracy of the real-time flood forecasting system by considering the influence of human activities.
13 Application effect of precipitation product deviation correction method in the Yangtze River basin
2024, 22(2):319-330.
Abstract:
As a key link in the water cycle, the uneven and unstable spatial and temporal distribution of precipitation directly causes natural disasters such as floods and droughts. Highly accurate precipitation data not only helps the research of hydrology, meteorology, and agriculture, but also can effectively be used to mitigate natural disasters such as floods. Although station observation is the most direct and accurate way to obtain precipitation, the distribution of ground stations is not uniform, which often does not reflect the spatial distribution of precipitation well. Precipitation products with high resolution, continuous spatial and temporal distribution, and easier access make up for the shortcomings of ground stations to a certain extent and are widely used in basin hydrological simulation and extreme precipitation prediction. However, their accuracies are affected by the nature of cloud cover, the performance of satellite sensors, and the inversion algorithms, which often show different degrees of bias, and need to be evaluated for applicability to verify their reliability before use. It has been shown that appropriate bias correction for less-than-optimal precipitation products can effectively improve their applicability.The bias correction of precipitation products are compared using seven methods in three categories to explore the bias correction methods applicable to different precipitation products and to evaluate the applicability of three precipitation products such as CMFD, MSWEP, and ERA5-Land based on the day-by-day precipitation observation data from surface meteorological stations from 1979 to 2018 in three sub-basins of the Yangtze River basin. Three types of precipitation products are compared with seven methods for bias correction, and nine evaluation indexes describing the detection capability, error size, degree of fit, and comprehensive evaluation are used to analyze and evaluate the applicability and correction effect to provide scientific and reasonable bias correction methods for the accurate application of precipitation products in different regions of the Yangtze River basin.The results show that the applicability of the corrected precipitation products was improved to different degrees, and the correction method combining local intensity scaling and triple gamma distribution was optimal for all three precipitation products and three sub-basins. There was no obvious relationship between the correction method and the type of precipitation products and the geographic location of the study area. There is an inverse correlation between the magnitude of correction of the correction methods and the applicability of the precipitation products in the study area, and the worse the applicability of the products, the more obvious the improvement of the accuracy evaluation indexes.The research can provide a referable calibration method for the accurate application of different precipitation products in different sub-basins of the Yangtze River basin at a later stage. A new correction method, local intensity scaling combined with three gamma distribution is constructed based on the segmented three-gamma distribution method by introducing the quantile optimization module and combining it with the local intensity scaling method, and it is applied to the correction of precipitation products. Compared with other bias correction methods, the combined local intensity scaling and triple gamma distribution method shows the best correction effect for the three precipitation products in three sub-basins, which is not only capable of correction, but also applicable, and can perform well and stably for the precipitation products with different characteristics and in regions with large differences in climate, topography and area.
As a key link in the water cycle, the uneven and unstable spatial and temporal distribution of precipitation directly causes natural disasters such as floods and droughts. Highly accurate precipitation data not only helps the research of hydrology, meteorology, and agriculture, but also can effectively be used to mitigate natural disasters such as floods. Although station observation is the most direct and accurate way to obtain precipitation, the distribution of ground stations is not uniform, which often does not reflect the spatial distribution of precipitation well. Precipitation products with high resolution, continuous spatial and temporal distribution, and easier access make up for the shortcomings of ground stations to a certain extent and are widely used in basin hydrological simulation and extreme precipitation prediction. However, their accuracies are affected by the nature of cloud cover, the performance of satellite sensors, and the inversion algorithms, which often show different degrees of bias, and need to be evaluated for applicability to verify their reliability before use. It has been shown that appropriate bias correction for less-than-optimal precipitation products can effectively improve their applicability.The bias correction of precipitation products are compared using seven methods in three categories to explore the bias correction methods applicable to different precipitation products and to evaluate the applicability of three precipitation products such as CMFD, MSWEP, and ERA5-Land based on the day-by-day precipitation observation data from surface meteorological stations from 1979 to 2018 in three sub-basins of the Yangtze River basin. Three types of precipitation products are compared with seven methods for bias correction, and nine evaluation indexes describing the detection capability, error size, degree of fit, and comprehensive evaluation are used to analyze and evaluate the applicability and correction effect to provide scientific and reasonable bias correction methods for the accurate application of precipitation products in different regions of the Yangtze River basin.The results show that the applicability of the corrected precipitation products was improved to different degrees, and the correction method combining local intensity scaling and triple gamma distribution was optimal for all three precipitation products and three sub-basins. There was no obvious relationship between the correction method and the type of precipitation products and the geographic location of the study area. There is an inverse correlation between the magnitude of correction of the correction methods and the applicability of the precipitation products in the study area, and the worse the applicability of the products, the more obvious the improvement of the accuracy evaluation indexes.The research can provide a referable calibration method for the accurate application of different precipitation products in different sub-basins of the Yangtze River basin at a later stage. A new correction method, local intensity scaling combined with three gamma distribution is constructed based on the segmented three-gamma distribution method by introducing the quantile optimization module and combining it with the local intensity scaling method, and it is applied to the correction of precipitation products. Compared with other bias correction methods, the combined local intensity scaling and triple gamma distribution method shows the best correction effect for the three precipitation products in three sub-basins, which is not only capable of correction, but also applicable, and can perform well and stably for the precipitation products with different characteristics and in regions with large differences in climate, topography and area.
2024, 22(2):331-338.
Abstract:
Under the influences of climate change and human activities, the hydrological process formation conditions in many basins and regions have changed significantly, and observed hydrological time series show growingly non-stationary characteristics. The uneven spatial and temporal distribution of water resources has been aggravated, resulting in new challenges for regional water resources management. It has been a hot topic to detect and attribute the changes in precipitation-runoff processes in changing environments. As the largest surface drinking water source in Beijing and the largest reservoir in north China, the Miyun Reservoir is responsible for water supply including urban, industries, and agriculture in the region. Precipitation-runoff processes upstream of the Miyun Reservoir also showed obvious non-stationary characteristics and extreme flooding events occurred in 2021 and 2023.For accurately identifying the non-stationary characteristics of hydrological processes in the Miyun Reservoir basin, and further clarifying its physical causes by considering the influences of both climate change and human activities, the observed annual data of precipitation and runoff from 1960 to 2019 were used. Multiple methods for time series analysis, including the Mann-Kendall test, hydrological alteration diagnosis system, and discrete wavelet spectrum for period identification were applied to detect the non-stationary characteristics (including trend, breakpoint, and periodicities) of precipitation and runoff. Based on the detection results, the Budyko framework-based water balance method was used to attribute the changes in runoff.Precipitation displayed random changes across the whole time, with no noteworthy trend, breakpoint, or period observed. However, runoff's non-stationary characteristics differed from those of precipitation. The decreasing trend of runoff was more significant compared with precipitation, and a significant breakpoint in 1979 was identified in the annual runoff time series. Based on that, from 1960 to 1979 was chosen as the baseline period, and the changes in runoff from 1980 to 1998 and from 1999 to 2019 were attributed to using the Budyko framework-based water balance method. The results indicated that human activities dominated the decrease in runoff in the Miyun Reservoir basin, compared to the influences of climate change. From 1980 to 1998, the soil and water conservation measures and constructions of hydraulic projects contributed ?111.40% of runoff compared to the baseline period, offsetting the runoff increase of 11.4% caused by climate change. From 1999 to 2019 change caused by dam construction and land use change was ?66.60% of the total runoff change, and climate change further aggravated ?33.40% of the change In recent years, the Miyun Reservoir basin has been in rainy periods, with higher precipitation compared to an average level. Coupled with the impacts of human activities on the runoff, the hydrological process and runoff present more complex variability in the Miyun Reservoir basin. Detection and attribution of the non-stationary characteristics of precipitation-runoff processes could be a useful basis for guiding the safe operation and water management of the Miyun Reservoir.
Under the influences of climate change and human activities, the hydrological process formation conditions in many basins and regions have changed significantly, and observed hydrological time series show growingly non-stationary characteristics. The uneven spatial and temporal distribution of water resources has been aggravated, resulting in new challenges for regional water resources management. It has been a hot topic to detect and attribute the changes in precipitation-runoff processes in changing environments. As the largest surface drinking water source in Beijing and the largest reservoir in north China, the Miyun Reservoir is responsible for water supply including urban, industries, and agriculture in the region. Precipitation-runoff processes upstream of the Miyun Reservoir also showed obvious non-stationary characteristics and extreme flooding events occurred in 2021 and 2023.For accurately identifying the non-stationary characteristics of hydrological processes in the Miyun Reservoir basin, and further clarifying its physical causes by considering the influences of both climate change and human activities, the observed annual data of precipitation and runoff from 1960 to 2019 were used. Multiple methods for time series analysis, including the Mann-Kendall test, hydrological alteration diagnosis system, and discrete wavelet spectrum for period identification were applied to detect the non-stationary characteristics (including trend, breakpoint, and periodicities) of precipitation and runoff. Based on the detection results, the Budyko framework-based water balance method was used to attribute the changes in runoff.Precipitation displayed random changes across the whole time, with no noteworthy trend, breakpoint, or period observed. However, runoff's non-stationary characteristics differed from those of precipitation. The decreasing trend of runoff was more significant compared with precipitation, and a significant breakpoint in 1979 was identified in the annual runoff time series. Based on that, from 1960 to 1979 was chosen as the baseline period, and the changes in runoff from 1980 to 1998 and from 1999 to 2019 were attributed to using the Budyko framework-based water balance method. The results indicated that human activities dominated the decrease in runoff in the Miyun Reservoir basin, compared to the influences of climate change. From 1980 to 1998, the soil and water conservation measures and constructions of hydraulic projects contributed ?111.40% of runoff compared to the baseline period, offsetting the runoff increase of 11.4% caused by climate change. From 1999 to 2019 change caused by dam construction and land use change was ?66.60% of the total runoff change, and climate change further aggravated ?33.40% of the change In recent years, the Miyun Reservoir basin has been in rainy periods, with higher precipitation compared to an average level. Coupled with the impacts of human activities on the runoff, the hydrological process and runoff present more complex variability in the Miyun Reservoir basin. Detection and attribution of the non-stationary characteristics of precipitation-runoff processes could be a useful basis for guiding the safe operation and water management of the Miyun Reservoir.
2024, 22(2):339-347,398.
Abstract:
In recent years, global climate change has intensified, leading to a northward shift of typhoon paths. Consequently, China's inland regions are increasingly experiencing persistent extreme precipitation events, which are significantly impacting agricultural production. As a crucial grain production base in the northwest region of China, Shaanxi has suffered a lot of extreme precipitation in recent years. During the period from 2010 to 2020, the climate in Shaanxi Province underwent pronounced fluctuations, marked by a notable increase in precipitation levels and a significant rise in the frequency of extreme precipitation events, resulting in substantial impacts on agricultural production. Therefore, to comprehend the recent patterns of extreme precipitation in the province, as well as to effectively prevent and control extreme precipitation disasters while mitigating potential economic losses, an assessment was conducted based on the precipitation data in Shaanxi Province from 2010 to 2020.This assessment took geographic terrain, vegetation cover, socio-economic attributes into consideration, and employed an evaluation framework including the hazard index, exposure index, and vulnerability index (HEV). This comprehensive approach enabled a detailed risk analysis regarding the impact of extreme precipitation on agricultural production in Shaanxi Province, creating a risk distribution map.The results indicate that, although the overall intensity of extreme precipitation events exhibited a decrease during the recent period, there was a discernible upward trend in the frequency of these events, specifically between the years 2015 and 2020. Subsequently, distinct computations of the HEV were carried out. The findings revealed higher hazard values concentrated in the eastern regions of the Guanzhong zones and southern Shaanxi, while relatively lower hazard values in the southern part of northern Shaanxi. Notably, Xi'an City was the highest exposure index in the province, while Yulin in northern Shaanxi had the lowest exposure index. The central parts of both the Guanzhong zones and Hanzhong showed higher vulnerability values, in contrast to the lower vulnerability values in the northern part of Hanzhong and the southern part of Baoji. Considering the comprehensive attributes encompassing hazard, exposure, and vulnerability, the risk analysis pinpointed several notable zones. Xianyang City's southern part, the northern part of Xi'an City, and the central part of Hanzhong were identified as high-risk zones, significantly susceptible to the impacts of extreme precipitation. On the other hand, the southern part of Xi'an City and the northern part of Hanzhong, characterized by higher exposure but lower hazard and vulnerability, fell within the medium-risk category. Areas with relatively lower socio-economic development, such as the northern regions of Shaanxi and the southern part of Baoji, were designated as low-risk zones within the context of this comprehensive risk assessment framework. Guided by the research findings, relevant authorities should emphasize specific strategies when addressing the impacts of extreme precipitation on agricultural production and livelihoods.In regions predominantly influenced by extreme precipitation intensity and frequency, like the southern part of Xianyang City, it is essential to enhance the precision and accuracy of early warnings and forecasts and refining responsive mechanisms. In high-risk areas primarily shaped by topography, such as the central part of Hanzhong City, appropriately increasing vegetation cover based on local water carrying capacity and improving agricultural infrastructure are recommended. In areas marked by high-density rural economies, such as the northern part of Xi'an City, efforts should be directed towards enhancing the disaster resilience of agricultural activities through crop optimization and management. This multidimensional risk analysis provides a theoretical foundation, enabling agricultural and water resource management authorities to effectively address the increasingly frequent and intense extreme precipitation disasters in a changing environment.
In recent years, global climate change has intensified, leading to a northward shift of typhoon paths. Consequently, China's inland regions are increasingly experiencing persistent extreme precipitation events, which are significantly impacting agricultural production. As a crucial grain production base in the northwest region of China, Shaanxi has suffered a lot of extreme precipitation in recent years. During the period from 2010 to 2020, the climate in Shaanxi Province underwent pronounced fluctuations, marked by a notable increase in precipitation levels and a significant rise in the frequency of extreme precipitation events, resulting in substantial impacts on agricultural production. Therefore, to comprehend the recent patterns of extreme precipitation in the province, as well as to effectively prevent and control extreme precipitation disasters while mitigating potential economic losses, an assessment was conducted based on the precipitation data in Shaanxi Province from 2010 to 2020.This assessment took geographic terrain, vegetation cover, socio-economic attributes into consideration, and employed an evaluation framework including the hazard index, exposure index, and vulnerability index (HEV). This comprehensive approach enabled a detailed risk analysis regarding the impact of extreme precipitation on agricultural production in Shaanxi Province, creating a risk distribution map.The results indicate that, although the overall intensity of extreme precipitation events exhibited a decrease during the recent period, there was a discernible upward trend in the frequency of these events, specifically between the years 2015 and 2020. Subsequently, distinct computations of the HEV were carried out. The findings revealed higher hazard values concentrated in the eastern regions of the Guanzhong zones and southern Shaanxi, while relatively lower hazard values in the southern part of northern Shaanxi. Notably, Xi'an City was the highest exposure index in the province, while Yulin in northern Shaanxi had the lowest exposure index. The central parts of both the Guanzhong zones and Hanzhong showed higher vulnerability values, in contrast to the lower vulnerability values in the northern part of Hanzhong and the southern part of Baoji. Considering the comprehensive attributes encompassing hazard, exposure, and vulnerability, the risk analysis pinpointed several notable zones. Xianyang City's southern part, the northern part of Xi'an City, and the central part of Hanzhong were identified as high-risk zones, significantly susceptible to the impacts of extreme precipitation. On the other hand, the southern part of Xi'an City and the northern part of Hanzhong, characterized by higher exposure but lower hazard and vulnerability, fell within the medium-risk category. Areas with relatively lower socio-economic development, such as the northern regions of Shaanxi and the southern part of Baoji, were designated as low-risk zones within the context of this comprehensive risk assessment framework. Guided by the research findings, relevant authorities should emphasize specific strategies when addressing the impacts of extreme precipitation on agricultural production and livelihoods.In regions predominantly influenced by extreme precipitation intensity and frequency, like the southern part of Xianyang City, it is essential to enhance the precision and accuracy of early warnings and forecasts and refining responsive mechanisms. In high-risk areas primarily shaped by topography, such as the central part of Hanzhong City, appropriately increasing vegetation cover based on local water carrying capacity and improving agricultural infrastructure are recommended. In areas marked by high-density rural economies, such as the northern part of Xi'an City, efforts should be directed towards enhancing the disaster resilience of agricultural activities through crop optimization and management. This multidimensional risk analysis provides a theoretical foundation, enabling agricultural and water resource management authorities to effectively address the increasingly frequent and intense extreme precipitation disasters in a changing environment.
2024, 22(2):348-358.
Abstract:
Water diversion project is an important measure to solve the uneven distribution of regional water resources, and effectively improve the ability of regional water security. Analyzing and evaluating the risks during the construction is of great importance for the project management. The risks during the construction of a water diversion project can be summarized as safety risks, progress risks, and investment risks. Considering only a single risk is not conducive to the overall management of the project, and it needs a comprehensive analysis of the project's systemic risk. The Yangtze-to-Huaihe River Water Diversion Project (Henan section) aims to supply water to urban and rural residents and improve the environment. This project is a long-distance water diversion project with a complex and changeable environment, along which there are many kinds of crossing structures such as roads and rivers. Some buildings are complicated in structure and difficult to construct. It is necessary to carry out a risk analysis of safety, progress, and investment system during the construction period for the Henan section to improve the safety and reliability of this project.Many factors affect the risk of safety, progress, and investment system, and there are mutual influences among these factors. Establishing a comprehensive index system for risk evaluation is the key to systemic risk analysis. Based on the established risk evaluation index system, the LEC method was used to evaluate the safety risk during the construction period, and the risk matrix method was used to evaluate the progress risk and investment risk. The results of risk evaluation for the single risk of safety, progress, and investment were obtained based on the analytic hierarchy process and fuzzy comprehensive risk assessment method. This process was divided into two steps: After the index matrix passed the consistency test, the analytic hierarchy process was used to determine the weight of each index and the fuzzy comprehensive assessment method was used to determine membership function. When analyzing safety, progress, and investment systemic risk, it was found that the statistical dimension of safety risk was inconsistent with the progress and investment risks. Therefore, this study proposed an improved comprehensive risk assessment method to analyze the comprehensive risks of safety, progress, and investment systems.The results showed that the evaluation results of single risk for safety, progress, and investment were 84.7, 0.806, and 0.802, respectively. All of the evaluation results were general. Because of the various approaches used, the resulting data had inconsistencies in statistical dimensions. Consequently, the results of the single risk assessment had to be normalized. Following that, the enhanced safety risk was 0.058, the enhanced progress risk was 0.012, and the improved investment risk was 0.006. The safety, progress, and investment systemic risks were the highest, commensurate with the project's real risk condition. Further analysis of the criterion layer and index layer in the index system showed that the risks of construction technology and scheme ranked first among the safety risks, which was the focus of subsequent risk management and control. The risks of lack of personnel cognition and the maintenance of equipment among the safety risks ranked second and third, respectively. As can be observed, the greatest impact on the construction of this project was the safety risk. Among the investment risks, the risk of erroneous project information was the lowest.This study provided theoretical and technical references to improve the reliability of the systemic risk and reduce the occurrence of risk events during the construction period for the Yangtze-to-Huaihe River Water Diversion Project (Henan section).
Water diversion project is an important measure to solve the uneven distribution of regional water resources, and effectively improve the ability of regional water security. Analyzing and evaluating the risks during the construction is of great importance for the project management. The risks during the construction of a water diversion project can be summarized as safety risks, progress risks, and investment risks. Considering only a single risk is not conducive to the overall management of the project, and it needs a comprehensive analysis of the project's systemic risk. The Yangtze-to-Huaihe River Water Diversion Project (Henan section) aims to supply water to urban and rural residents and improve the environment. This project is a long-distance water diversion project with a complex and changeable environment, along which there are many kinds of crossing structures such as roads and rivers. Some buildings are complicated in structure and difficult to construct. It is necessary to carry out a risk analysis of safety, progress, and investment system during the construction period for the Henan section to improve the safety and reliability of this project.Many factors affect the risk of safety, progress, and investment system, and there are mutual influences among these factors. Establishing a comprehensive index system for risk evaluation is the key to systemic risk analysis. Based on the established risk evaluation index system, the LEC method was used to evaluate the safety risk during the construction period, and the risk matrix method was used to evaluate the progress risk and investment risk. The results of risk evaluation for the single risk of safety, progress, and investment were obtained based on the analytic hierarchy process and fuzzy comprehensive risk assessment method. This process was divided into two steps: After the index matrix passed the consistency test, the analytic hierarchy process was used to determine the weight of each index and the fuzzy comprehensive assessment method was used to determine membership function. When analyzing safety, progress, and investment systemic risk, it was found that the statistical dimension of safety risk was inconsistent with the progress and investment risks. Therefore, this study proposed an improved comprehensive risk assessment method to analyze the comprehensive risks of safety, progress, and investment systems.The results showed that the evaluation results of single risk for safety, progress, and investment were 84.7, 0.806, and 0.802, respectively. All of the evaluation results were general. Because of the various approaches used, the resulting data had inconsistencies in statistical dimensions. Consequently, the results of the single risk assessment had to be normalized. Following that, the enhanced safety risk was 0.058, the enhanced progress risk was 0.012, and the improved investment risk was 0.006. The safety, progress, and investment systemic risks were the highest, commensurate with the project's real risk condition. Further analysis of the criterion layer and index layer in the index system showed that the risks of construction technology and scheme ranked first among the safety risks, which was the focus of subsequent risk management and control. The risks of lack of personnel cognition and the maintenance of equipment among the safety risks ranked second and third, respectively. As can be observed, the greatest impact on the construction of this project was the safety risk. Among the investment risks, the risk of erroneous project information was the lowest.This study provided theoretical and technical references to improve the reliability of the systemic risk and reduce the occurrence of risk events during the construction period for the Yangtze-to-Huaihe River Water Diversion Project (Henan section).
2024, 22(2):359-367.
Abstract:
As the main infrastructure of the water conservancy project, the concrete dam undertakes the functions of power generation, flood control and shipping. However, the fatigue damage inside the concrete, caused from repeated loads such as water, temperature and earthquake, accumulates continuously. The durability of the dam is seriously reduced and the stiffness is rapidly degraded, which endangers the normal operation of the dam. However, previous studies mainly focused on single static and dynamic load conditions. In addition, scholars often used wet screening concrete specimens, which were made of coarse aggregates with a particle size greater than 40 mm slowly after screening, to indirectly obtain the basic properties of dam concrete. Due to the influence of aggregate chain effect, it was difficult to accurately reflect the mechanical properties of dam concrete. Therefore, it is helpful to the construction of dam engineering and improves the safety of concrete dams, considering the influence of initial cyclic damage on the fracture characteristics of full-graded dams.In order to study the effects of increased cyclic amplitude (2.5 kN, 5.0 kN, 7.5 kN) on the fracture characteristics of full-graded concrete, three-point bending fracture test was carried out on fully-graded concrete specimens subjected to initial cyclic damage. The fracture damage process was monitored by acoustic emission technology. The results showed that the greater the increased amplitude of the initial cyclic load, the greater the cumulative damage of concrete beams in the initial cyclic damage stage. Moreover, the peak load after damage decreases correspondingly, and the brittleness characteristic is more obvious. Through the analysis of AE b-value, it is found that after the peak load, b-value had a significant decline stage. At this stage, the microcracks in the beam rapidly converged and expanded into macroscopic cracks. Late in the loading phase, the b-value fluctuated slowly around 1.0. It indicated that new micro-cracks were continuously generated inside the specimen and expanded into macroscopic cracks. The formation of macroscopic cracks in the loading process can be well characterized by the change of b-value. By comparing the AE damage index of energy, ringing count and impact number, it could be found that the damage index curves of the three groups of specimens appeared multiple points of intersection with the advance of the loading process. The damage index of impact number was more sensitive to the overall damage, while the damage index of the energy was more sensitive to the local damage. Through the analysis of RA-AF values, it could be seen that the proportion of shear cracks increases with the loading time, which is mainly due to the presence of large aggregate and boundary effect. But the proportion of tensile cracks always dominates. By comparing the shear crack proportion curves of the three groups of specimens, it could be found that the larger the amplitude with the initial cycle, the larger the proportion of shear cracks during failure.It can be concluded that the dynamic damage process of full-graded concrete specimens could be well characterized by analyzing acoustic emission parameters such as ringing number, energy and amplitude. It is showed that the greater the increase of initial cyclic load, the more serious the stiffness attenuation of dam concrete and the more obvious brittleness characteristics. Besides, in the middle and late loading period, the fracture characteristics of the sample were mainly affected by the distribution of large aggregates, but not by the initial cyclic damage. In addition, the effect of different initial cyclic damage on the fracture behavior of full-graded concrete was obtained, which could provide practical value for predicting the fracture failure of concrete dam.
As the main infrastructure of the water conservancy project, the concrete dam undertakes the functions of power generation, flood control and shipping. However, the fatigue damage inside the concrete, caused from repeated loads such as water, temperature and earthquake, accumulates continuously. The durability of the dam is seriously reduced and the stiffness is rapidly degraded, which endangers the normal operation of the dam. However, previous studies mainly focused on single static and dynamic load conditions. In addition, scholars often used wet screening concrete specimens, which were made of coarse aggregates with a particle size greater than 40 mm slowly after screening, to indirectly obtain the basic properties of dam concrete. Due to the influence of aggregate chain effect, it was difficult to accurately reflect the mechanical properties of dam concrete. Therefore, it is helpful to the construction of dam engineering and improves the safety of concrete dams, considering the influence of initial cyclic damage on the fracture characteristics of full-graded dams.In order to study the effects of increased cyclic amplitude (2.5 kN, 5.0 kN, 7.5 kN) on the fracture characteristics of full-graded concrete, three-point bending fracture test was carried out on fully-graded concrete specimens subjected to initial cyclic damage. The fracture damage process was monitored by acoustic emission technology. The results showed that the greater the increased amplitude of the initial cyclic load, the greater the cumulative damage of concrete beams in the initial cyclic damage stage. Moreover, the peak load after damage decreases correspondingly, and the brittleness characteristic is more obvious. Through the analysis of AE b-value, it is found that after the peak load, b-value had a significant decline stage. At this stage, the microcracks in the beam rapidly converged and expanded into macroscopic cracks. Late in the loading phase, the b-value fluctuated slowly around 1.0. It indicated that new micro-cracks were continuously generated inside the specimen and expanded into macroscopic cracks. The formation of macroscopic cracks in the loading process can be well characterized by the change of b-value. By comparing the AE damage index of energy, ringing count and impact number, it could be found that the damage index curves of the three groups of specimens appeared multiple points of intersection with the advance of the loading process. The damage index of impact number was more sensitive to the overall damage, while the damage index of the energy was more sensitive to the local damage. Through the analysis of RA-AF values, it could be seen that the proportion of shear cracks increases with the loading time, which is mainly due to the presence of large aggregate and boundary effect. But the proportion of tensile cracks always dominates. By comparing the shear crack proportion curves of the three groups of specimens, it could be found that the larger the amplitude with the initial cycle, the larger the proportion of shear cracks during failure.It can be concluded that the dynamic damage process of full-graded concrete specimens could be well characterized by analyzing acoustic emission parameters such as ringing number, energy and amplitude. It is showed that the greater the increase of initial cyclic load, the more serious the stiffness attenuation of dam concrete and the more obvious brittleness characteristics. Besides, in the middle and late loading period, the fracture characteristics of the sample were mainly affected by the distribution of large aggregates, but not by the initial cyclic damage. In addition, the effect of different initial cyclic damage on the fracture behavior of full-graded concrete was obtained, which could provide practical value for predicting the fracture failure of concrete dam.
2024, 22(2):368-377.
Abstract:
There are many risks in the operation of the South-to-North Water Transfers Project, and the inspection work of the South-to-North Water Transfers Project is of great significance to ensure the safety and stability of the project. Traditional project inspection methods mainly rely on manual experience and have a low degree of digitalization. Due to the uneven professional level of inspection personnel, it is difficult to form a unified record standard, which in turn leads to redundant inspection special report information, among which the accessibility of effective information is poor, making the traditional project inspection method inefficient.As a new generation of information technology, knowledge graph is a powerful tool for knowledge organization and management. In order to alleviate the limitations of traditional project inspection methods and improve the efficiency of project inspection, knowledge graph with deep learning technology was combined, and using knowledge graph to empower intelligent inspection of the South-to-North Water Transfers Project was proposed. Specifically, the inspection knowledge graph was constructed based on the project inspection text, and an project risk information recommendation method was designed based on the inspection knowledge graph. In the process of building the inspection knowledge graph, the conceptual model of the inspection knowledge graph is defined based on expert experience, and on this basis, the entity relationship joint extraction framework is used to extract the structured triplet knowledge from the unstructured project inspection text, and the knowledge visualization is carried out with the Neo4j graph database as the carrier. The inspection knowledge graph clearly presents inspection information such as engineering sites, parts, risk events, and disposal measures in the form of entity-relationship-entity triples, and supports knowledge visualization and knowledge retrieval, which alleviates the limitation of poor accessibility of effective information in inspection reports. In the project risk information recommendation method, the Bert pre-training model and twin network framework were used to design the Bert twin network, and recommends the project risk information of the entities and entities associated with the current part in the inspection knowledge graph to the inspectors by calculating the string similarity of the part entities, and assists the inspectors in the project risk level diagnosis. The quality of the knowledge graph and the effectiveness of the method are evaluated experimentally. The experimental results show that the average F1 value of various relational triples extracted is 88.42%, and the knowledge extraction results have high accuracy, and the quality of the knowledge graph is considered to be reliable. The F1 value of the candidate entity ranking model designed reaches 86%, which is higher than that of the traditional Jaccard algorithm and Word2Vec model.In general, the Bert twin network designed shows good performance in the string similarity calculation task, and the project risk information recommendation results based on patrol inspection knowledge graph are basically reliable. Knowledge graph and deep learning technology were introduced into the intelligent application of project inspection, which realizes the deep correlation and effective use of inspection knowledge, which can provide reference significance for improving the operation and maintenance efficiency of the South-to-North Water Transfers Project and strengthening the risk management capability of the project.
There are many risks in the operation of the South-to-North Water Transfers Project, and the inspection work of the South-to-North Water Transfers Project is of great significance to ensure the safety and stability of the project. Traditional project inspection methods mainly rely on manual experience and have a low degree of digitalization. Due to the uneven professional level of inspection personnel, it is difficult to form a unified record standard, which in turn leads to redundant inspection special report information, among which the accessibility of effective information is poor, making the traditional project inspection method inefficient.As a new generation of information technology, knowledge graph is a powerful tool for knowledge organization and management. In order to alleviate the limitations of traditional project inspection methods and improve the efficiency of project inspection, knowledge graph with deep learning technology was combined, and using knowledge graph to empower intelligent inspection of the South-to-North Water Transfers Project was proposed. Specifically, the inspection knowledge graph was constructed based on the project inspection text, and an project risk information recommendation method was designed based on the inspection knowledge graph. In the process of building the inspection knowledge graph, the conceptual model of the inspection knowledge graph is defined based on expert experience, and on this basis, the entity relationship joint extraction framework is used to extract the structured triplet knowledge from the unstructured project inspection text, and the knowledge visualization is carried out with the Neo4j graph database as the carrier. The inspection knowledge graph clearly presents inspection information such as engineering sites, parts, risk events, and disposal measures in the form of entity-relationship-entity triples, and supports knowledge visualization and knowledge retrieval, which alleviates the limitation of poor accessibility of effective information in inspection reports. In the project risk information recommendation method, the Bert pre-training model and twin network framework were used to design the Bert twin network, and recommends the project risk information of the entities and entities associated with the current part in the inspection knowledge graph to the inspectors by calculating the string similarity of the part entities, and assists the inspectors in the project risk level diagnosis. The quality of the knowledge graph and the effectiveness of the method are evaluated experimentally. The experimental results show that the average F1 value of various relational triples extracted is 88.42%, and the knowledge extraction results have high accuracy, and the quality of the knowledge graph is considered to be reliable. The F1 value of the candidate entity ranking model designed reaches 86%, which is higher than that of the traditional Jaccard algorithm and Word2Vec model.In general, the Bert twin network designed shows good performance in the string similarity calculation task, and the project risk information recommendation results based on patrol inspection knowledge graph are basically reliable. Knowledge graph and deep learning technology were introduced into the intelligent application of project inspection, which realizes the deep correlation and effective use of inspection knowledge, which can provide reference significance for improving the operation and maintenance efficiency of the South-to-North Water Transfers Project and strengthening the risk management capability of the project.
ZHANG?Wei
,
，DENG?Binbin
，QIU?Jianchun
,
，XIA?Guochun
,
，YAO?Zhaoren
，LIU?Zhanwu
，
ZHU?Xinyu
，WANG?Yujin
2024, 22(2):378-387,408.
Abstract:
The excavation and deformation of deep foundation pits for sluice gates were influenced by various factors, including engineering and hydrogeological conditions, spatial dimensions of the foundation pit, type of support structure, and excavation stage. Additionally, random environmental factors such as vibrations from construction machinery, loads from surrounding traffic, and weather conditions play a role. The excavation-induced deformation of these foundation pits exhibited significant nonlinearity and instability. The deformation monitoring data acquired from the excavation site of the foundation pit consist of a series of multimodal sequences across various temporal dimensions. Scientifically identifying key data features in different dimensions and subsequently modelling and predicting them in a targeted manner holds significant importance. The extreme-point symmetric mode decomposition method (ESMD) was employed for the prototype monitoring sequences of deformation during the deep excavation of a sluice foundation pit, involving multimodal decomposition. The deformation monitoring data of the sluice foundation pit were decomposed into several distinct subsequence components, intrinsic mode functions (IMFs), and trend components (Res), each exhibiting unique features. Fuzzy entropy (FE) theory was utilized, and fuzzy multimodal phase space reconstruction was applied to each modal subsequence component and trend component, resulting in multiple reconstructed subsequence components. Physically significant features of sluice foundation pit deformation at various time scales were effectively discerned through this process. Subsequently, a model was constructed based on the artificial jellyfish search optimizer (AJSO)-optimized long short-term memory (LSTM) artificial neural network. The optimization involved training on the reconstructed subsequences, yielding an AJSO-LSTM optimized model for each reconstructed subsequence. Finally, using the optimized AJSO-LSTM models, dynamic predictions were made for each reconstructed subsequence at fixed time intervals. The predicted results for each reconstructed subsequence were synthesized to obtain the overall prediction of foundation pit deformation. To evaluate the prediction accuracy of the ESMD-FE-AJSO-LSTM model for foundation pit deformation, multiple accuracy evaluation metrics were introduced.Taking the excavation deformation monitoring of the Eleven Weir Riverbank Hub Reconstruction Project in Zhangjiagang city as an example, the methods described above are employed to predict and analyse the excavation-induced deformations in the hub project. The results indicate that this approach can effectively forecast the nonlinear characteristics of excavation-induced deformations. The multidimensional feature scale components obtained through the ESMD algorithm exhibit distinct physical oscillation characteristics. Simultaneously, the calculation results of the variance contribution rate for each mode indicate that the short-term fluctuation in the deformation of the sluice foundation pit is mainly dominated by the high-frequency modes IMF1 and IMF2, while the long-term fluctuation is primarily governed by the trend component Res. The consistency between these decomposition results and on-site observations demonstrates that the ESMD method is effective at identifying the physical characteristics of excavation-induced deformation at different time scales. The proposed ESMD-FE-AJSO-LSTM method achieves an overall deformation prediction accuracy ranging from 97.63% to 99.52%. The prediction results generally fall between those of the AJSO-LSTM, LSTM, RNN, and SVM algorithms, indicating that the ESMD-FE-AJSO-LSTM model presented has higher predictive accuracy. The predicted residuals of the ESMD-FE-AJSO-LSTM method fluctuate near the zero-value mean and exhibit an overall normal distribution. This finding suggested that the proposed method has better predictive stability and robustness than the other four models, indicating its practical value in scientific and engineering applications.
The excavation and deformation of deep foundation pits for sluice gates were influenced by various factors, including engineering and hydrogeological conditions, spatial dimensions of the foundation pit, type of support structure, and excavation stage. Additionally, random environmental factors such as vibrations from construction machinery, loads from surrounding traffic, and weather conditions play a role. The excavation-induced deformation of these foundation pits exhibited significant nonlinearity and instability. The deformation monitoring data acquired from the excavation site of the foundation pit consist of a series of multimodal sequences across various temporal dimensions. Scientifically identifying key data features in different dimensions and subsequently modelling and predicting them in a targeted manner holds significant importance. The extreme-point symmetric mode decomposition method (ESMD) was employed for the prototype monitoring sequences of deformation during the deep excavation of a sluice foundation pit, involving multimodal decomposition. The deformation monitoring data of the sluice foundation pit were decomposed into several distinct subsequence components, intrinsic mode functions (IMFs), and trend components (Res), each exhibiting unique features. Fuzzy entropy (FE) theory was utilized, and fuzzy multimodal phase space reconstruction was applied to each modal subsequence component and trend component, resulting in multiple reconstructed subsequence components. Physically significant features of sluice foundation pit deformation at various time scales were effectively discerned through this process. Subsequently, a model was constructed based on the artificial jellyfish search optimizer (AJSO)-optimized long short-term memory (LSTM) artificial neural network. The optimization involved training on the reconstructed subsequences, yielding an AJSO-LSTM optimized model for each reconstructed subsequence. Finally, using the optimized AJSO-LSTM models, dynamic predictions were made for each reconstructed subsequence at fixed time intervals. The predicted results for each reconstructed subsequence were synthesized to obtain the overall prediction of foundation pit deformation. To evaluate the prediction accuracy of the ESMD-FE-AJSO-LSTM model for foundation pit deformation, multiple accuracy evaluation metrics were introduced.Taking the excavation deformation monitoring of the Eleven Weir Riverbank Hub Reconstruction Project in Zhangjiagang city as an example, the methods described above are employed to predict and analyse the excavation-induced deformations in the hub project. The results indicate that this approach can effectively forecast the nonlinear characteristics of excavation-induced deformations. The multidimensional feature scale components obtained through the ESMD algorithm exhibit distinct physical oscillation characteristics. Simultaneously, the calculation results of the variance contribution rate for each mode indicate that the short-term fluctuation in the deformation of the sluice foundation pit is mainly dominated by the high-frequency modes IMF1 and IMF2, while the long-term fluctuation is primarily governed by the trend component Res. The consistency between these decomposition results and on-site observations demonstrates that the ESMD method is effective at identifying the physical characteristics of excavation-induced deformation at different time scales. The proposed ESMD-FE-AJSO-LSTM method achieves an overall deformation prediction accuracy ranging from 97.63% to 99.52%. The prediction results generally fall between those of the AJSO-LSTM, LSTM, RNN, and SVM algorithms, indicating that the ESMD-FE-AJSO-LSTM model presented has higher predictive accuracy. The predicted residuals of the ESMD-FE-AJSO-LSTM method fluctuate near the zero-value mean and exhibit an overall normal distribution. This finding suggested that the proposed method has better predictive stability and robustness than the other four models, indicating its practical value in scientific and engineering applications.
2024, 22(2):388-398.
Abstract:
With China's extensive water transfers projects underway, the focus has shifted towards optimizing their operation, highlighting the significance of pumping station efficiency studies. The efficiency characteristic curve, a fundamental feature, plays a crucial role in optimizing station operation by utilizing measured head-flow data. However, long-term operation introduces efficiency errors, stemming from design inaccuracies, mechanical losses, fluid friction, operational errors, and improper maintenance. This is evident in cases like pumping Unit 4 at the Pizhou station, where substantial disparities between actual and theoretical efficiency exist, necessitating precise efficiency simulation models to align optimization schemes with the actual optimal state. Recent endeavors have integrated machine learning algorithms like polynomial regression, Gaussian process regression, and neural networks into hydraulic forecasting and simulation, offering promising avenues for pumping station efficiency simulation. Therefore, employing artificial intelligence techniques to investigate pumping station efficiency simulation was proposed, focusing on a representative station of the Eastern Route of the South-to-North Water Transfers Project.The efficiency simulation of pumping units in water management systems is a critical task, demanding meticulous preprocessing of operational data and the selection of appropriate modeling techniques. Initially, data preprocessing involves aligning time-stamped measurements, clustering data into windows, and handling anomalies to ensure data quality. Various influencing factors, such as flow rates, water levels, and blade rotating angles, are scrutinized to optimize efficiency modeling. Traditional methods, like Polynomial Regression and Multivariate Linear Regression, are contrasted with advanced techniques including decision regression trees, support vector regression, Gaussian process regression, and neural networks. Each method offers unique advantages, such as the interpretability of decision trees and the flexibility of neural networks. Training these models involves careful parameter selection and validation using established metrics like root mean squared error and determination coefficient. Python and MATLAB are prominent tools used for implementation, offering libraries and functions tailored for regression tasks. The average indicators of the eight pumping units indicate that GPR (Gaussian process regression) models with three different kernel functions (RQ, SE, E) exhibit the best overall performance in simulating the efficiency of the four units at the Pizhou station and the four units at the Suining station. The indicator shows the three GPR models are around 0.34 to 0.36, while ANN, DNN, and MLR are slightly above 0.5, with other models showing poorer performance. In terms of the R2 indicator, except for DRT and SVM models, which are approximately between 0.7 and 0.8, all other models score above 0.9. Regarding the EMI indicator, traditional polynomials (2nd PR and 3rd PR) perform the worst, while other models are within approximately 5, with the three GPR models ranging from 3.2 to 3.5, showing better performance. Considering the five metrics ERMS,EMA,R2,EMS and EMI, the GPR models demonstrate the best overall performance among various traditional and machine learning methods in the comprehensive testing. Comparing efficiency simulation methods, incorporating station upstream and downstream water levels alongside traditional head as features yielded superior results, notably enhancing model performance in various metrics. This approach, particularly evident in GPR models, addresses non-linear relationships and potential error sources in head calculations. Utilizing station water levels directly improves model accuracy, offering a more intuitive analysis of influencing factors.In conclusion, after analyzing ten regression models for pump efficiency simulation, the GPR model emerged as the most effective, outperforming traditional polynomial methods. Evaluation metrics showed significantly superior performance of GPR over other models, evidenced by reduced errors across various indicators when applied to training datasets of eight pump units at two stations. Substituting station water levels for traditional head as input features yielded notable improvements in model accuracy, particularly evident in GPR models. For instance, using GPR for efficiency simulation at one pump unit resulted in average and maximum absolute errors within 0.50% and 3.20% respectively, while employing water levels instead of head further reduced these errors to 0.41% and 2.30%. This enhancement signifies a substantial improvement over current methods, offering precise efficiency simulation crucial for optimizing pump station operations.
With China's extensive water transfers projects underway, the focus has shifted towards optimizing their operation, highlighting the significance of pumping station efficiency studies. The efficiency characteristic curve, a fundamental feature, plays a crucial role in optimizing station operation by utilizing measured head-flow data. However, long-term operation introduces efficiency errors, stemming from design inaccuracies, mechanical losses, fluid friction, operational errors, and improper maintenance. This is evident in cases like pumping Unit 4 at the Pizhou station, where substantial disparities between actual and theoretical efficiency exist, necessitating precise efficiency simulation models to align optimization schemes with the actual optimal state. Recent endeavors have integrated machine learning algorithms like polynomial regression, Gaussian process regression, and neural networks into hydraulic forecasting and simulation, offering promising avenues for pumping station efficiency simulation. Therefore, employing artificial intelligence techniques to investigate pumping station efficiency simulation was proposed, focusing on a representative station of the Eastern Route of the South-to-North Water Transfers Project.The efficiency simulation of pumping units in water management systems is a critical task, demanding meticulous preprocessing of operational data and the selection of appropriate modeling techniques. Initially, data preprocessing involves aligning time-stamped measurements, clustering data into windows, and handling anomalies to ensure data quality. Various influencing factors, such as flow rates, water levels, and blade rotating angles, are scrutinized to optimize efficiency modeling. Traditional methods, like Polynomial Regression and Multivariate Linear Regression, are contrasted with advanced techniques including decision regression trees, support vector regression, Gaussian process regression, and neural networks. Each method offers unique advantages, such as the interpretability of decision trees and the flexibility of neural networks. Training these models involves careful parameter selection and validation using established metrics like root mean squared error and determination coefficient. Python and MATLAB are prominent tools used for implementation, offering libraries and functions tailored for regression tasks. The average indicators of the eight pumping units indicate that GPR (Gaussian process regression) models with three different kernel functions (RQ, SE, E) exhibit the best overall performance in simulating the efficiency of the four units at the Pizhou station and the four units at the Suining station. The indicator shows the three GPR models are around 0.34 to 0.36, while ANN, DNN, and MLR are slightly above 0.5, with other models showing poorer performance. In terms of the R2 indicator, except for DRT and SVM models, which are approximately between 0.7 and 0.8, all other models score above 0.9. Regarding the EMI indicator, traditional polynomials (2nd PR and 3rd PR) perform the worst, while other models are within approximately 5, with the three GPR models ranging from 3.2 to 3.5, showing better performance. Considering the five metrics ERMS,EMA,R2,EMS and EMI, the GPR models demonstrate the best overall performance among various traditional and machine learning methods in the comprehensive testing. Comparing efficiency simulation methods, incorporating station upstream and downstream water levels alongside traditional head as features yielded superior results, notably enhancing model performance in various metrics. This approach, particularly evident in GPR models, addresses non-linear relationships and potential error sources in head calculations. Utilizing station water levels directly improves model accuracy, offering a more intuitive analysis of influencing factors.In conclusion, after analyzing ten regression models for pump efficiency simulation, the GPR model emerged as the most effective, outperforming traditional polynomial methods. Evaluation metrics showed significantly superior performance of GPR over other models, evidenced by reduced errors across various indicators when applied to training datasets of eight pump units at two stations. Substituting station water levels for traditional head as input features yielded notable improvements in model accuracy, particularly evident in GPR models. For instance, using GPR for efficiency simulation at one pump unit resulted in average and maximum absolute errors within 0.50% and 3.20% respectively, while employing water levels instead of head further reduced these errors to 0.41% and 2.30%. This enhancement signifies a substantial improvement over current methods, offering precise efficiency simulation crucial for optimizing pump station operations.
2024, 22(2):399-408.
Abstract:
The spillway is an important structure to ensure the safe discharge of the reservoir and the safe operation of the dam body. In order to ensure the safe operation of the spillway, the hydraulic characteristics of the spillway of the Goushuipo Reservoir reinforcement project were tested and studied, and the engineering design was validated and optimized. Based on SolidWorks software, the three-dimensional numerical model of the spillway of the Goushuipo Reservoir was established by the VOF method, and the closed N-S equation of RNG k-εturbulence model were used to simulate the spillway of the Goushuipo Reservoir reinforcement project by Fluent software. Based on the conditions of 30-year flood and 50-year flood, the data of spillway water surface line simulated by mathematical model was slightly different from that measured by physical model only in the silting pool, and the maximum deviation of water surface line was 9.2%. Using numerical simulation method to correct and simulate the original design scheme had higher simulation accuracy and reliability.The relation function of water level and discharge was established, and the variation law of water flow along the spillway was analyzed. Under the design conditions, the flood level of the stilling pool and the tail channel of the reservoir exceeded the top of the slope protection. The reason why the concrete slope protection height of the spillway could not meet the normal flood discharge under the 30-year flood condition of the Goushuipo reservoir reinforcement project was deeply analyzed. An optimization scheme was proposed to set two-stage water mat in the slope section of the reservoir, increase the slope protection height of the silencing pool section and shorten the length of the tail channel. The numerical simulation results showed that the rhomboid flow in the slope section of the spillway was destroyed, and the discharging energy of part of the flow was reduced. After the flood enters the silencing pool, the rolling degree of the flow was weakened, the flow state was relatively stable, and the energy dissipation effect was remarkable. The water surface line of steep slope section, stilling pool and sea section of bend did not exceed the top of slope protection. Based on the optimization scheme, the problem that the slope protection height of spillway can not discharge floodwater normally under the design condition was solved, and the scheme provided a reference for engineering optimization design.Through comparison and analysis of the numerical simulation results of the spillway of Goushuipo reservoir with the physical model test results, the numerical simulation method have high accuracy and reliability, and the numerical simulation method can be used to study and analyze the hydraulic characteristics of the spillway along the water surface elevation, flow velocity and flow pattern, pressure, discharge, and energy dissipation and erosion evolution law and to optimize the spillway structure in a targeted manner. The relationship function of water level and discharge obtained by fitting analysis provides a reference for design and operation. The research results provide technical support for numerical simulation of similar spillway projects.
The spillway is an important structure to ensure the safe discharge of the reservoir and the safe operation of the dam body. In order to ensure the safe operation of the spillway, the hydraulic characteristics of the spillway of the Goushuipo Reservoir reinforcement project were tested and studied, and the engineering design was validated and optimized. Based on SolidWorks software, the three-dimensional numerical model of the spillway of the Goushuipo Reservoir was established by the VOF method, and the closed N-S equation of RNG k-εturbulence model were used to simulate the spillway of the Goushuipo Reservoir reinforcement project by Fluent software. Based on the conditions of 30-year flood and 50-year flood, the data of spillway water surface line simulated by mathematical model was slightly different from that measured by physical model only in the silting pool, and the maximum deviation of water surface line was 9.2%. Using numerical simulation method to correct and simulate the original design scheme had higher simulation accuracy and reliability.The relation function of water level and discharge was established, and the variation law of water flow along the spillway was analyzed. Under the design conditions, the flood level of the stilling pool and the tail channel of the reservoir exceeded the top of the slope protection. The reason why the concrete slope protection height of the spillway could not meet the normal flood discharge under the 30-year flood condition of the Goushuipo reservoir reinforcement project was deeply analyzed. An optimization scheme was proposed to set two-stage water mat in the slope section of the reservoir, increase the slope protection height of the silencing pool section and shorten the length of the tail channel. The numerical simulation results showed that the rhomboid flow in the slope section of the spillway was destroyed, and the discharging energy of part of the flow was reduced. After the flood enters the silencing pool, the rolling degree of the flow was weakened, the flow state was relatively stable, and the energy dissipation effect was remarkable. The water surface line of steep slope section, stilling pool and sea section of bend did not exceed the top of slope protection. Based on the optimization scheme, the problem that the slope protection height of spillway can not discharge floodwater normally under the design condition was solved, and the scheme provided a reference for engineering optimization design.Through comparison and analysis of the numerical simulation results of the spillway of Goushuipo reservoir with the physical model test results, the numerical simulation method have high accuracy and reliability, and the numerical simulation method can be used to study and analyze the hydraulic characteristics of the spillway along the water surface elevation, flow velocity and flow pattern, pressure, discharge, and energy dissipation and erosion evolution law and to optimize the spillway structure in a targeted manner. The relationship function of water level and discharge obtained by fitting analysis provides a reference for design and operation. The research results provide technical support for numerical simulation of similar spillway projects.
2024, 22(2):409-416.
Abstract:
The forebay is a structure connecting the suction sump (inlet passage) and the diversion channel (igniting river) of the pumping station, and its flow pattern has a direct impact on the safe and stable operation of the pumping station unit. The drainage flow and diversion flow of Xihe pumping station in Zhongshan City, Guangdong Province, are both very large, and the diversion condition is lateral inflow. Higher requirements are now set forward for the flow conditions of the forebay of the pumping station. If the incoming flow of the forebay is not uniform, there will be adverse flow patterns such as bias flow, deflected flow, backflow, and air-core vortex, which will adversely affect the safe operation of the Xihe pumping station and the operating efficiency of the unit.In order to clarify the flow pattern characteristics of the forebay of Xihe pumping station during the operation of asymmetric units, taken the Xihe pumping station project as the research object, the physical model test method was used to carry out the overall physical model test of the forebay and inlet passage of the pumping station during different startup combinations. The computational fluid dynamic technology was used to numerically analyze the operation scheme of eight units fully open at the lowest water level.It was found that, when the eight units of the Xihe pumping station are fully opened for drainage, the mainstream is centered in the inland river diversion section. The surface velocity in the mainstream zone is mostly in the range of 0.9 m/s to 1.2 m/s and the surface velocity in front of the inlet of the pumping station is in the range of 0 to 0.6 m/s. In the outlet sump and the outer river section of the pumping station, the surface velocity in the mainstream zone is mostly in the range of 0.9 m/s to 1.2 m/s, and the maximum velocity is 1.44 m/s. The flow pattern of the upstream and downstream diversion sections of the pumping station is relatively smooth. The water surface fluctuation at the inlet of the pumping station is small, and the water flow is relatively stable and smooth. Under the asymmetric unit operation scheme 2, the surface velocity in the mainstream zone of the inland river diversion section is mostly in the range of 0.6 m/s to1.0 m/s and the surface velocity in front of the inlet of the pumping station is in the range of 0 to 0.4 m/s. In the outlet sump and the outer river section of the pumping station, the surface velocity in the mainstream zone is mostly in the range of 0.6 m/s to 1.0 m/s, and the maximum velocity is 1.32 m/s. Affected by the non-startup of the number 1 and number 8 units, the flow velocity at the middle bottom is greater than that on both sides, and a weak recirculation zone is formed at the inlet of the non-startup unit, but there is no harmful surface vortex. Under start-up scheme 3, the surface velocity in the mainstream zone of the inland river diversion section is mostly in the range of 0.6 m/s to 1.0 m/s and the surface velocity in front of the inlet of the pumping station is in the range of 0 to 0.4 m/s. In the outlet sump and the outer river section of the pumping station, the surface velocity in the mainstream zone is mostly in the range of 0.6 m/s to 1.0 m/s, and the maximum velocity is 1.47 m/s. The bottom velocity distribution of the upstream section of the pumping station is more uniform along the section, and the bottom velocity distribution of the downstream section of the pumping station is also affected by the non-startup pump, with the bottom velocity in the range of 0.35 m/s to 0.81 m/s and 0.42 m/s to 0.61 m/s, respectively. Under start-up scheme 4, whose flow pattern of the forebay is stable and the uniformity of the bottom velocity distribution of the inlet section is 77.2%, the flow field distribution of the inlet and outlet surfaces of the pumping station is similar to that of start-up scheme 3. Under the conditions of full load drainage flow and the lowest water level, the difference in velocity distribution on both sides of the pier of the inlet passage of the side unit is more significant, and the difference in velocity distribution of the middle unit is smaller. There are some differences in the axial velocity distribution uniformity and velocity weighted average angle on both sides of the pier of the inlet passage of the intermediate unit and the side unit. Therefore, the safety and stability of the operation of the side unit should be paid attention to when the unit is fully opened.The followings are the results: (1) When the eight units of Xihe pumping station are fully opened for full load drainage and the lowest water level, the surface velocity in front of the inlet of the pumping station is small. The water surface fluctuation at the inlet of the pumping station is small and the water surface fluctuation at the outlet of the pumping station is slightly larger. The average uniformity of the axial velocity distribution in the inlet passage of eight units is 74.31%, and the average value of the velocity weighted average angle is 81.18°. The hydraulic performance index of the inlet surface of the inlet passage of the units on both sides is the lowest, and the stability and energy consumption of the operation are the largest. (2) At 75% of drainage load, the startup schemes of three different units were analyzed by a physical model. Under start-up scheme 3, the inlet flow pattern of the pumping station was stable. There was no obvious swirling flow, and the uniformity of velocity distribution at the bottom of the inlet section was 78.2 %, which was higher than that of startup scheme 2 and startup scheme 4. Startup scheme 3 was recommended at 75% of the drainage load. The research results can provide a certain reference value for the actual operation and management of Xihe pumping station.
The forebay is a structure connecting the suction sump (inlet passage) and the diversion channel (igniting river) of the pumping station, and its flow pattern has a direct impact on the safe and stable operation of the pumping station unit. The drainage flow and diversion flow of Xihe pumping station in Zhongshan City, Guangdong Province, are both very large, and the diversion condition is lateral inflow. Higher requirements are now set forward for the flow conditions of the forebay of the pumping station. If the incoming flow of the forebay is not uniform, there will be adverse flow patterns such as bias flow, deflected flow, backflow, and air-core vortex, which will adversely affect the safe operation of the Xihe pumping station and the operating efficiency of the unit.In order to clarify the flow pattern characteristics of the forebay of Xihe pumping station during the operation of asymmetric units, taken the Xihe pumping station project as the research object, the physical model test method was used to carry out the overall physical model test of the forebay and inlet passage of the pumping station during different startup combinations. The computational fluid dynamic technology was used to numerically analyze the operation scheme of eight units fully open at the lowest water level.It was found that, when the eight units of the Xihe pumping station are fully opened for drainage, the mainstream is centered in the inland river diversion section. The surface velocity in the mainstream zone is mostly in the range of 0.9 m/s to 1.2 m/s and the surface velocity in front of the inlet of the pumping station is in the range of 0 to 0.6 m/s. In the outlet sump and the outer river section of the pumping station, the surface velocity in the mainstream zone is mostly in the range of 0.9 m/s to 1.2 m/s, and the maximum velocity is 1.44 m/s. The flow pattern of the upstream and downstream diversion sections of the pumping station is relatively smooth. The water surface fluctuation at the inlet of the pumping station is small, and the water flow is relatively stable and smooth. Under the asymmetric unit operation scheme 2, the surface velocity in the mainstream zone of the inland river diversion section is mostly in the range of 0.6 m/s to1.0 m/s and the surface velocity in front of the inlet of the pumping station is in the range of 0 to 0.4 m/s. In the outlet sump and the outer river section of the pumping station, the surface velocity in the mainstream zone is mostly in the range of 0.6 m/s to 1.0 m/s, and the maximum velocity is 1.32 m/s. Affected by the non-startup of the number 1 and number 8 units, the flow velocity at the middle bottom is greater than that on both sides, and a weak recirculation zone is formed at the inlet of the non-startup unit, but there is no harmful surface vortex. Under start-up scheme 3, the surface velocity in the mainstream zone of the inland river diversion section is mostly in the range of 0.6 m/s to 1.0 m/s and the surface velocity in front of the inlet of the pumping station is in the range of 0 to 0.4 m/s. In the outlet sump and the outer river section of the pumping station, the surface velocity in the mainstream zone is mostly in the range of 0.6 m/s to 1.0 m/s, and the maximum velocity is 1.47 m/s. The bottom velocity distribution of the upstream section of the pumping station is more uniform along the section, and the bottom velocity distribution of the downstream section of the pumping station is also affected by the non-startup pump, with the bottom velocity in the range of 0.35 m/s to 0.81 m/s and 0.42 m/s to 0.61 m/s, respectively. Under start-up scheme 4, whose flow pattern of the forebay is stable and the uniformity of the bottom velocity distribution of the inlet section is 77.2%, the flow field distribution of the inlet and outlet surfaces of the pumping station is similar to that of start-up scheme 3. Under the conditions of full load drainage flow and the lowest water level, the difference in velocity distribution on both sides of the pier of the inlet passage of the side unit is more significant, and the difference in velocity distribution of the middle unit is smaller. There are some differences in the axial velocity distribution uniformity and velocity weighted average angle on both sides of the pier of the inlet passage of the intermediate unit and the side unit. Therefore, the safety and stability of the operation of the side unit should be paid attention to when the unit is fully opened.The followings are the results: (1) When the eight units of Xihe pumping station are fully opened for full load drainage and the lowest water level, the surface velocity in front of the inlet of the pumping station is small. The water surface fluctuation at the inlet of the pumping station is small and the water surface fluctuation at the outlet of the pumping station is slightly larger. The average uniformity of the axial velocity distribution in the inlet passage of eight units is 74.31%, and the average value of the velocity weighted average angle is 81.18°. The hydraulic performance index of the inlet surface of the inlet passage of the units on both sides is the lowest, and the stability and energy consumption of the operation are the largest. (2) At 75% of drainage load, the startup schemes of three different units were analyzed by a physical model. Under start-up scheme 3, the inlet flow pattern of the pumping station was stable. There was no obvious swirling flow, and the uniformity of velocity distribution at the bottom of the inlet section was 78.2 %, which was higher than that of startup scheme 2 and startup scheme 4. Startup scheme 3 was recommended at 75% of the drainage load. The research results can provide a certain reference value for the actual operation and management of Xihe pumping station.
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