Volume 0,Issue 6,2023 Table of Contents
2023(6):1041-1048.
Abstract:
The Western Route Project constitutes a pivotal component within the framework of the South-to-North Water Transfers Project, serving as the main framework and artery of the national water resources allocation pattern with “four horizontal and three vertical”. Its significance resonates profoundly in the preservation of ecological security within the Yellow River basin, the establishment of a national ecological security barrier, the advancement of economic and social development across the northweatern region, solving the problem of imbalanced and insufficient development, and maintaining social stability. After over 70 years of argumentation, the first phase of the Western Route of South-to-North Water Transfers Project is currently recommended as the 8 billion m3 combined water transfer scheme. It consists of two independent water transfer routes, the upper and lower lines, both of which are self-flowing water transfer. Specifically, the upper route will transfer 4 billion m3 of water from the mainstream of the Yalong River and the tributaries of the Dadu River to the mainstream of the Yellow River near the mouth of the Jiaqu River. The lower route will transfer the other 4 billion m3 of water from the Shuangjiangkou Reservoir on the Dadu River, which is under construction, to the Tao River. The total length of the first phase of the Western Route Project is 740 km, including a tunnel length of 731 km and the construction of 6 new water source reservoirs. The total static investment of the project is about 257.6 billion yuan, which may be a heavy burden on national investment and construction if it is totally founded by the state. It is worth noting that the water receiving area of the Western Route of the South-to-North Water Transfers Project highly overlaps with some national strategies regions in the upper and middle reaches of the Yellow River, including the development of the Western region, the Belt and Road, ecological security, food security, energy security, and “double carbon”. This territory is inherently endowed with a profusion of natural resources, including wind, solar, and expansive tracts of land, which can be synergistically harnessed in conjunction with the Western Route Project for comprehensive development to increase project financial income and expand financing channels. In light of these considerations, in alignment with the “two-pronged approach” mandate, a holistic development model denoted as “Water Transfer + Energy (Livestock Farming) Agriculture (Land)” is posited. This model serves as a strategic mechanism to mitigate the financial strains associated with the Western Route Project, capitalizing on the abundant reservoir of land resources, wind energy potential, and solar energy availability within the hinterlands of the Western Route Project’s service area. This comprehensive development includes building a clean energy base with multi-energy forms, developing the Heishan Gorge ecological irrigation area, and building a comprehensive development base of light energy and animal husbandry in the inland river area. In addition, two financing modes were proposed: (1) All revenues generated from clean energy will be exclusively allocated to the construction of the first phase of the Western Route Project and basic operation without considering state funding; (2) The construction of clean energy bases is determined in accordance with the comprehensive development plan scale, and feedback the Western Route Project in the form of electricity price subsidies. Results showed that, under the integrated development with 8 billion m3 water transfer amount of the Western Route Project, it can build a multi-energy complementary clean energy base with an installed capacity of 641.05 million kW, develop 0.336 million hm2 of ecological irrigation area in Heishan Gorge. Furthermore, it supports the establishment of an integrated platform for harnessing light energy and animal husbandry in the inland river basin to breed 5 million sheep. Several financing models were proposed. The total financial revenue of the comprehensive development plan for the first phase of the Western Route Project is about 357.6 billion yuan, and the overall pre-tax financial internal rate of return before financing is 6.5% to 7.3%.
The Western Route Project constitutes a pivotal component within the framework of the South-to-North Water Transfers Project, serving as the main framework and artery of the national water resources allocation pattern with “four horizontal and three vertical”. Its significance resonates profoundly in the preservation of ecological security within the Yellow River basin, the establishment of a national ecological security barrier, the advancement of economic and social development across the northweatern region, solving the problem of imbalanced and insufficient development, and maintaining social stability. After over 70 years of argumentation, the first phase of the Western Route of South-to-North Water Transfers Project is currently recommended as the 8 billion m3 combined water transfer scheme. It consists of two independent water transfer routes, the upper and lower lines, both of which are self-flowing water transfer. Specifically, the upper route will transfer 4 billion m3 of water from the mainstream of the Yalong River and the tributaries of the Dadu River to the mainstream of the Yellow River near the mouth of the Jiaqu River. The lower route will transfer the other 4 billion m3 of water from the Shuangjiangkou Reservoir on the Dadu River, which is under construction, to the Tao River. The total length of the first phase of the Western Route Project is 740 km, including a tunnel length of 731 km and the construction of 6 new water source reservoirs. The total static investment of the project is about 257.6 billion yuan, which may be a heavy burden on national investment and construction if it is totally founded by the state. It is worth noting that the water receiving area of the Western Route of the South-to-North Water Transfers Project highly overlaps with some national strategies regions in the upper and middle reaches of the Yellow River, including the development of the Western region, the Belt and Road, ecological security, food security, energy security, and “double carbon”. This territory is inherently endowed with a profusion of natural resources, including wind, solar, and expansive tracts of land, which can be synergistically harnessed in conjunction with the Western Route Project for comprehensive development to increase project financial income and expand financing channels. In light of these considerations, in alignment with the “two-pronged approach” mandate, a holistic development model denoted as “Water Transfer + Energy (Livestock Farming) Agriculture (Land)” is posited. This model serves as a strategic mechanism to mitigate the financial strains associated with the Western Route Project, capitalizing on the abundant reservoir of land resources, wind energy potential, and solar energy availability within the hinterlands of the Western Route Project’s service area. This comprehensive development includes building a clean energy base with multi-energy forms, developing the Heishan Gorge ecological irrigation area, and building a comprehensive development base of light energy and animal husbandry in the inland river area. In addition, two financing modes were proposed: (1) All revenues generated from clean energy will be exclusively allocated to the construction of the first phase of the Western Route Project and basic operation without considering state funding; (2) The construction of clean energy bases is determined in accordance with the comprehensive development plan scale, and feedback the Western Route Project in the form of electricity price subsidies. Results showed that, under the integrated development with 8 billion m3 water transfer amount of the Western Route Project, it can build a multi-energy complementary clean energy base with an installed capacity of 641.05 million kW, develop 0.336 million hm2 of ecological irrigation area in Heishan Gorge. Furthermore, it supports the establishment of an integrated platform for harnessing light energy and animal husbandry in the inland river basin to breed 5 million sheep. Several financing models were proposed. The total financial revenue of the comprehensive development plan for the first phase of the Western Route Project is about 357.6 billion yuan, and the overall pre-tax financial internal rate of return before financing is 6.5% to 7.3%.
2023(6):1049-1054,1063.
Abstract:
At the present stage, the basic theoretical knowledge and systematic research on national water network is still weak, which largely restricts the scientific planning and construction of national water network. To this end, the basic concepts of network, water network and national water network are analysed from the basic cognition of national water network. The basic problems of water network are initially explored in terms of the main features such as water network structure, bearers, evolutionary laws, functional roles, and type division. The target guidelines was putforward for the construction of water network with the core objective of realising a healthy water cycle, the promotion of the six balances as the basic guideline, and the principles of "real need, ecological safety, and sustainability" for the demonstration of major projects. A new trend in the construction of future water networks is envisaged, with a view to providing support for the scientific construction of national water networks at the theoretical level.
At the present stage, the basic theoretical knowledge and systematic research on national water network is still weak, which largely restricts the scientific planning and construction of national water network. To this end, the basic concepts of network, water network and national water network are analysed from the basic cognition of national water network. The basic problems of water network are initially explored in terms of the main features such as water network structure, bearers, evolutionary laws, functional roles, and type division. The target guidelines was putforward for the construction of water network with the core objective of realising a healthy water cycle, the promotion of the six balances as the basic guideline, and the principles of "real need, ecological safety, and sustainability" for the demonstration of major projects. A new trend in the construction of future water networks is envisaged, with a view to providing support for the scientific construction of national water networks at the theoretical level.
2023(6):1055-1063.
Abstract:
Based on the new development stage, there is a compelling exigency to fortify the top-level design, strategic layout, and the establishment of a more systematic, higher standard, resilient, and secure national water network. This imperative is grounded in the evolving landscape, fresh imperatives of modernization, and emerging duties pertaining to national water security. It is a long-term, systematic, and strategic project to build up the national water network. It has an important guiding function and practical significance to divide the overall strategy into basic tactics for promoting the construction of the national water network step by step. Water network construction practice and related research progress from the perspective of the domestic and foreign were summarized comprehensively. The conceptual connotations, compositional framework, functional structure, and inherent advantages underpinning the national water network are systematically delved. The basic theory and principles of national water network construction were put forward, and the main task and technical route of national water network planning and construction were also defined. The profound meaning of overall strategy, basic strategy, and the dialectical relationship between them were analyzed from the perspective of universal meaning and methodology. Builc upon this foundational analysis, the strategic and tactic relationship of national water network planning and construction was analyzed from the aspects of the basic idea and specific measures to direct the planning and construction of the national water network, national water network system structure and composition, hierarchy system of the nation-province-city-county water network, functions and task of the national water network. The analytical insights and recommendations proffered are expected to provide strategic support and tactic reserves for the planning and construction of the national water network.
Based on the new development stage, there is a compelling exigency to fortify the top-level design, strategic layout, and the establishment of a more systematic, higher standard, resilient, and secure national water network. This imperative is grounded in the evolving landscape, fresh imperatives of modernization, and emerging duties pertaining to national water security. It is a long-term, systematic, and strategic project to build up the national water network. It has an important guiding function and practical significance to divide the overall strategy into basic tactics for promoting the construction of the national water network step by step. Water network construction practice and related research progress from the perspective of the domestic and foreign were summarized comprehensively. The conceptual connotations, compositional framework, functional structure, and inherent advantages underpinning the national water network are systematically delved. The basic theory and principles of national water network construction were put forward, and the main task and technical route of national water network planning and construction were also defined. The profound meaning of overall strategy, basic strategy, and the dialectical relationship between them were analyzed from the perspective of universal meaning and methodology. Builc upon this foundational analysis, the strategic and tactic relationship of national water network planning and construction was analyzed from the aspects of the basic idea and specific measures to direct the planning and construction of the national water network, national water network system structure and composition, hierarchy system of the nation-province-city-county water network, functions and task of the national water network. The analytical insights and recommendations proffered are expected to provide strategic support and tactic reserves for the planning and construction of the national water network.
2023(6):1064-1071,1079.
Abstract:
On the premise of ensuring the safety of water delivery in winter, it is an important measure to adopt non-ice-covered large discharge water delivery mode to enhance the main canal water conveyance capacity of the South-to-North Water Transfers Project in winter, the thermal insulation of canal water conveyance is one of the key technical bottlenecks to ensure the operation of non-ice-covered water conveyance of main canal. Based on the analysis of the water temperature and ice condition in the 8 winters since the water supply of the whole line under the current regulation of the Middle Route project, the operation method of non-ice-covered large-flow water conveyance is put forward to realize water conveyance and heat preservation in winter, aiming at four kinds of dispatching operation schemes of different water flow, such as 350, 280, 210 and 150 m3/s, simulation analysis of each scheme of water transfer in strong cold winter, cold winter, flat winter and warm winter weather conditions such as the winter heat preservation effect of the main canal. On this basis, a proposal for optimal operation of non-ice-covered water conveyance and thermal insulation of main canal in winter is proposed. The results of numerical simulation show that: according to different typical winter weather conditions, the non-ice-covered large-flow water transfer operation mode is adopted under limited conditions, it can shorten the flow time of water conveyance and reduce the heat loss of water body, thus achieving the effect of heat preservation, the water temperature at the end of the open channel is also higher than that at the end of the open channel, at the same time, it can also effectively solve the problem of limited water conveyance capacity in winter.Based on the short-term air temperature forecast and water temperature forecast in the main canal, it is suggested that water transfer operation mode with larger water discharge should be adopted as far as possible under the typical winter weather conditions such as cold winter, flat winter and warm winter, and under the strong cold winter weather conditions, non-ice-cap large flow water conveyance model can be used in time and channel sections.
On the premise of ensuring the safety of water delivery in winter, it is an important measure to adopt non-ice-covered large discharge water delivery mode to enhance the main canal water conveyance capacity of the South-to-North Water Transfers Project in winter, the thermal insulation of canal water conveyance is one of the key technical bottlenecks to ensure the operation of non-ice-covered water conveyance of main canal. Based on the analysis of the water temperature and ice condition in the 8 winters since the water supply of the whole line under the current regulation of the Middle Route project, the operation method of non-ice-covered large-flow water conveyance is put forward to realize water conveyance and heat preservation in winter, aiming at four kinds of dispatching operation schemes of different water flow, such as 350, 280, 210 and 150 m3/s, simulation analysis of each scheme of water transfer in strong cold winter, cold winter, flat winter and warm winter weather conditions such as the winter heat preservation effect of the main canal. On this basis, a proposal for optimal operation of non-ice-covered water conveyance and thermal insulation of main canal in winter is proposed. The results of numerical simulation show that: according to different typical winter weather conditions, the non-ice-covered large-flow water transfer operation mode is adopted under limited conditions, it can shorten the flow time of water conveyance and reduce the heat loss of water body, thus achieving the effect of heat preservation, the water temperature at the end of the open channel is also higher than that at the end of the open channel, at the same time, it can also effectively solve the problem of limited water conveyance capacity in winter.Based on the short-term air temperature forecast and water temperature forecast in the main canal, it is suggested that water transfer operation mode with larger water discharge should be adopted as far as possible under the typical winter weather conditions such as cold winter, flat winter and warm winter, and under the strong cold winter weather conditions, non-ice-cap large flow water conveyance model can be used in time and channel sections.
2023(6):1072-1079.
Abstract:
Large scale water diversion projects are the key to achieving optimal allocation of water resources and the foundation for building national water network. They have the characteristics of wide cross basin coverage areas and complex operating conditions due to the variety of hydraulic structures. The method of investigation and research is adopted to investigate the current construction status of digital twins in large-scale water transfer projects such as the Zhejiang East Water Transfers Project, the Qiandao Lake Water Distribution Project, and the East Route of the South-to-North Water Transfers Project. Based on the characteristics of each project, the characteristics of their digital twin construction are analyzed, and the experience of digital twin construction in the above-mentioned large-scale water diversion projects is summarized. On this basis, the requirements for the construction of digital twins in the subsequent projects of the South-to-North Water Transfers Project were analyzed, and several suggestions for the construction of digital twins in the South-to-North Water Transfers Project were proposed, providing reference for the subsequent construction of digital twins in the South-to-North Water Teansfers Project.
Large scale water diversion projects are the key to achieving optimal allocation of water resources and the foundation for building national water network. They have the characteristics of wide cross basin coverage areas and complex operating conditions due to the variety of hydraulic structures. The method of investigation and research is adopted to investigate the current construction status of digital twins in large-scale water transfer projects such as the Zhejiang East Water Transfers Project, the Qiandao Lake Water Distribution Project, and the East Route of the South-to-North Water Transfers Project. Based on the characteristics of each project, the characteristics of their digital twin construction are analyzed, and the experience of digital twin construction in the above-mentioned large-scale water diversion projects is summarized. On this basis, the requirements for the construction of digital twins in the subsequent projects of the South-to-North Water Transfers Project were analyzed, and several suggestions for the construction of digital twins in the South-to-North Water Transfers Project were proposed, providing reference for the subsequent construction of digital twins in the South-to-North Water Teansfers Project.
2023(6):1080-1088.
Abstract:
The Middle Route of the South-to-North Water Transfers Project is a major strategic infrastructure project to optimize the allocation of water resources and improve the ecological environment in China. However, due to the limited level of planning and information construction, there are a series of challenges, including that the water supply destination cannot realize the optimal dispatching of water transport to achieve supply and demand balance, the automatic degree of early warning in water quality monitoring is inadequate, the disposal of water contamination accident lacks scientific decision-making support and the engineering safety risks cannot be actively and accurately warned. In order to provide scientific and technological support for the construction of the digital twin of Middle Route of South-to-North Water Transfers Project, to provide a model for the construction of digital twins in other water transfers projects, and to support the acceleration of construction of digital twins in the national water network of China, this paper aims to build a unified data base plate, improve the ability of information infrastructure, build a digital twin Middle Route model platform and knowledge platform, and finally realize the precise decision support for the safe operation of the Middle Route and water resources scheduling on the basis of the Middle Route spatio-temporal information service map. Based on the construction status of the Middle Route of South-to-North Water Transfers Project and the characteristics of digital twin technology, the gap between the informatization status and the requirements of digital twin construction was analyzed. According to the requirements of digital twin construction, the overall thought of the construction of the digital twin of Middle Route of South-to-North Water Transfers Project from two frame design and technical route planning based on the construction status of the project and characteristics digital twin technology is put forward.The implementation path is elaborated in detail with the principle of “three safety” of engineering safety, water supply safety and water quality safety and the core objectives of improving the level of digitization, networking and intelligence of the project, and strengthening the four pre-functions of “forecast, early warning, preview and plan”. The key construction contents of digital twin platform, engineering safety application, water supply safety application, water quality safety application and standard specification system are clarified. Through the establishment of the standard system required for the construction and management of the digital twin of South-to-North Water Transfers Project with systematic thinking, it comprehensively covers the business areas of the South-to-North Water Transfers Project, and is unified and coordinated to meet the construction and management needs of the digital twin business of the South-to-North Water Transfers Project. Through the three-step construction of digital twin of Middle Route of South-to-North Water Transfers Project, that is, the local effect in the first year, the overall promotion in the second year, and the enabling application in the third year, the synchronous simulation operation and iterative optimization of the physical Middle Route and the digital Middle Route are realized, helping the Middle Route to play a greater role in the development of the national economy. As an important component of the backbone network of the national water network, the South-to-North Water Transfers Project should play a leading role in scientific and technological innovation, and make industry demonstrations in promoting the digitization of water networks, intelligent dispatching, automation of monitoring and early warning, strengthening the integration of physical water networks and digital water networks, and improving the level of science and technology and intelligence of water network projects, which provides an important reference for the construction of the digital twin of Middle Route of South-to-North Water Transfers Project.
The Middle Route of the South-to-North Water Transfers Project is a major strategic infrastructure project to optimize the allocation of water resources and improve the ecological environment in China. However, due to the limited level of planning and information construction, there are a series of challenges, including that the water supply destination cannot realize the optimal dispatching of water transport to achieve supply and demand balance, the automatic degree of early warning in water quality monitoring is inadequate, the disposal of water contamination accident lacks scientific decision-making support and the engineering safety risks cannot be actively and accurately warned. In order to provide scientific and technological support for the construction of the digital twin of Middle Route of South-to-North Water Transfers Project, to provide a model for the construction of digital twins in other water transfers projects, and to support the acceleration of construction of digital twins in the national water network of China, this paper aims to build a unified data base plate, improve the ability of information infrastructure, build a digital twin Middle Route model platform and knowledge platform, and finally realize the precise decision support for the safe operation of the Middle Route and water resources scheduling on the basis of the Middle Route spatio-temporal information service map. Based on the construction status of the Middle Route of South-to-North Water Transfers Project and the characteristics of digital twin technology, the gap between the informatization status and the requirements of digital twin construction was analyzed. According to the requirements of digital twin construction, the overall thought of the construction of the digital twin of Middle Route of South-to-North Water Transfers Project from two frame design and technical route planning based on the construction status of the project and characteristics digital twin technology is put forward.The implementation path is elaborated in detail with the principle of “three safety” of engineering safety, water supply safety and water quality safety and the core objectives of improving the level of digitization, networking and intelligence of the project, and strengthening the four pre-functions of “forecast, early warning, preview and plan”. The key construction contents of digital twin platform, engineering safety application, water supply safety application, water quality safety application and standard specification system are clarified. Through the establishment of the standard system required for the construction and management of the digital twin of South-to-North Water Transfers Project with systematic thinking, it comprehensively covers the business areas of the South-to-North Water Transfers Project, and is unified and coordinated to meet the construction and management needs of the digital twin business of the South-to-North Water Transfers Project. Through the three-step construction of digital twin of Middle Route of South-to-North Water Transfers Project, that is, the local effect in the first year, the overall promotion in the second year, and the enabling application in the third year, the synchronous simulation operation and iterative optimization of the physical Middle Route and the digital Middle Route are realized, helping the Middle Route to play a greater role in the development of the national economy. As an important component of the backbone network of the national water network, the South-to-North Water Transfers Project should play a leading role in scientific and technological innovation, and make industry demonstrations in promoting the digitization of water networks, intelligent dispatching, automation of monitoring and early warning, strengthening the integration of physical water networks and digital water networks, and improving the level of science and technology and intelligence of water network projects, which provides an important reference for the construction of the digital twin of Middle Route of South-to-North Water Transfers Project.
2023(6):1089-1097.
Abstract:
With the large negative cumulative temperature of China’s northern latitude in winter, the ice conditions occurring in the channel are prone to develop into ice disasters such as ice jams and ice dams. For the consideration of disaster mitigation, water transmission in the channel during the ice period is often operated by controlling the flow velocity and Fr value, using the mode of water transmission under ice cover, i.e., forming a stable ice cover, changing the heat exchange between water and the outside. However, this method of water conveyance reduces the water flow and restricts the engineering benefits. In the mode of water transmission under the ice cover, it is difficult to get a substantial increase in the way of water transmission capacity based on improving the accuracy of meteorological and ice forecasting, improving the efficiency and quality of hydraulic regulation to shorten the range and length of the channel section of the water transmission during the ice period. Therefore, the channel project with a certain size of trapezoidal section as an example was taken and the sensitive factors affecting the channel water temperature in the ice period was analyzed through a numerical simulation method. On this basis, the formula for the unfrozen length of the channel is obtained through multivariate fitting and researches the hydraulic-thermal synergistic regulation method of transferring water externally into the channel to eliminate the ice condition by increasing the heat of the channel water.According to the established ice-period water transfer model, a 60-km-long channel was simulated. The influence laws of winter air temperature, headwater temperature, and water delivery flow on the along-range attenuation of channel water temperature were analyzed, and the unfrozen length formula of the channel was obtained by the multivariate fitting, the temperature control effect of two offline recharge modes of reservoirs on the channel water body was analyzed, the influence of recharge flow, air temperature and recharge water temperature on the maximal recharge interval was analyzed, and the unfrozen length formula was used to calculate the maximal recharge spacing. From the simulation results, it can be seen that: the channel water temperature decreases along the course during the ice period, and the unfrozen length is proportional to the water flow (Q) and the water temperature in the inlet channel (T0), and inversely proportional to the absolute value of the negative temperature (?Ta). The maximum spacing of recharge water in the two modes of recharge conventional water replenishment and cyclic recharge is related to the recharge flow rate, the air temperature and recharge water temperature, and the larger the recharge flow rate, the higher the outside air temperature, the higher the recharge water temperature, the larger the spacing between the recharge point settings. According to the numerical simulation results, the relationship equations between the maximum spacing of recharge and the ratio of recharge flow rate, the temperature difference between the channel water and the atmosphere, and the temperature difference between the channel water and the recharge water were obtained. From the point of view of unfrozen length, under the same meteorological conditions, water delivery conditions, recharge flow rate, and thermal conditions, the unfrozen length in the recirculating recharge mode increases by about 4.9% to 5.9% compared with the conventional recharge mode, and fewer recharge points need to be set up. The calculated values of the unfrozen length formula are in good agreement with the numerical simulation value.By transferring water externally into the channel, the unfrozen length of the channel can be extended, and the channel can avoid freezing within a certain water transmission distance, thus avoiding ice-covered water transmission, which can solve the bottleneck problem of insufficient water transmission capacity of the long-distance water transmission channel in the ice period.
With the large negative cumulative temperature of China’s northern latitude in winter, the ice conditions occurring in the channel are prone to develop into ice disasters such as ice jams and ice dams. For the consideration of disaster mitigation, water transmission in the channel during the ice period is often operated by controlling the flow velocity and Fr value, using the mode of water transmission under ice cover, i.e., forming a stable ice cover, changing the heat exchange between water and the outside. However, this method of water conveyance reduces the water flow and restricts the engineering benefits. In the mode of water transmission under the ice cover, it is difficult to get a substantial increase in the way of water transmission capacity based on improving the accuracy of meteorological and ice forecasting, improving the efficiency and quality of hydraulic regulation to shorten the range and length of the channel section of the water transmission during the ice period. Therefore, the channel project with a certain size of trapezoidal section as an example was taken and the sensitive factors affecting the channel water temperature in the ice period was analyzed through a numerical simulation method. On this basis, the formula for the unfrozen length of the channel is obtained through multivariate fitting and researches the hydraulic-thermal synergistic regulation method of transferring water externally into the channel to eliminate the ice condition by increasing the heat of the channel water.According to the established ice-period water transfer model, a 60-km-long channel was simulated. The influence laws of winter air temperature, headwater temperature, and water delivery flow on the along-range attenuation of channel water temperature were analyzed, and the unfrozen length formula of the channel was obtained by the multivariate fitting, the temperature control effect of two offline recharge modes of reservoirs on the channel water body was analyzed, the influence of recharge flow, air temperature and recharge water temperature on the maximal recharge interval was analyzed, and the unfrozen length formula was used to calculate the maximal recharge spacing. From the simulation results, it can be seen that: the channel water temperature decreases along the course during the ice period, and the unfrozen length is proportional to the water flow (Q) and the water temperature in the inlet channel (T0), and inversely proportional to the absolute value of the negative temperature (?Ta). The maximum spacing of recharge water in the two modes of recharge conventional water replenishment and cyclic recharge is related to the recharge flow rate, the air temperature and recharge water temperature, and the larger the recharge flow rate, the higher the outside air temperature, the higher the recharge water temperature, the larger the spacing between the recharge point settings. According to the numerical simulation results, the relationship equations between the maximum spacing of recharge and the ratio of recharge flow rate, the temperature difference between the channel water and the atmosphere, and the temperature difference between the channel water and the recharge water were obtained. From the point of view of unfrozen length, under the same meteorological conditions, water delivery conditions, recharge flow rate, and thermal conditions, the unfrozen length in the recirculating recharge mode increases by about 4.9% to 5.9% compared with the conventional recharge mode, and fewer recharge points need to be set up. The calculated values of the unfrozen length formula are in good agreement with the numerical simulation value.By transferring water externally into the channel, the unfrozen length of the channel can be extended, and the channel can avoid freezing within a certain water transmission distance, thus avoiding ice-covered water transmission, which can solve the bottleneck problem of insufficient water transmission capacity of the long-distance water transmission channel in the ice period.
2023(6):1098-1108.
Abstract:
In cold regions, such as high latitudes during winter, rivers and water conveyance channels often experience the phenomenon of freezing under low temperature conditions. During the initial stage of freezing and the subsequent melting stage, ice floes are prone to get stuck in the channels, forming ice jams and dams, which obstruct the flow of water and raise the water level in the channels, thus adversely affecting winter water transfer. Cold waves and extreme low temperatures in the region often cause significant temperature fluctuations, which are the main factors influencing changes in the ice conditions of rivers and channels. The Middle Route of South-to-North Water Transfers Project (MRSWTP) spans multiple latitudes, and the areas north of the Yellow River are affected by ice conditions to varying degrees every year during winter operations. Therefore, analyzing the spatiotemporal variations of cold waves and regional extreme low temperatures along the MRSWTP is of great significance for ice disaster prevention, winter water transportation scheduling, and other related issues.Based on the daily minimum and maximum air temperature data of meteorological stations within a width of 40 km along the route from the head of Taocha Drainage Canal to the Beijuma Culvert of the MRSWTP from 1960 to 2020, the occurrences of cold waves and five extreme cold climate indices were calculated. The Sen’s slope estimator method was employed to analyze their trends. Additionally, the spatial variations of the five extreme climate indices were analyzed using the inverse distance weighting spatial interpolation method based on temperature data from 56 meteorological stations.The results show that among the nine typical weather stations selected, the frequency of cold waves in seven weather stations decreased from 1960 to 2020. The frequency of cold waves in Anyang and Baoding stations showed a downward trend, but since 2000, the number of cold waves has increased significantly. January has the highest frequency of cold waves occurrences, followed by December, February, and November. The regions north of Xingtai show an increasing trend in cold waves occurrence with rising latitudes. As for the extreme climate indices, the minimum value of the annual minimum temperature at the nine meteorological stations generally exhibits an increasing trend from 1960 to 2020. However, since 1990, Baoding station has shown an abnormal trend of not increasing but rather decreasing, while Xingtai and Shijiazhuang stations have remained in a state of stagnation without further increase. The other four extreme climate indices, including frost days (the number of days with a daily minimum temperature below 0 ℃) and freeze days (the number of days with a daily maximum temperature below 0 ℃), generally exhibit different decreasing trends, but some stations show abnormal trends of not decreasing but instead increasing or stagnating. Moreover, it is found that the decline rate of the number of days with a daily minimum temperature below 0 ℃ is faster compared to the decline rate of the number of days with a daily maximum temperature below 0 ℃, indicating a more significant impact of climate change. There is no consistent trend detected among the various climate indices in terms of spatial changes. For freeze days, the decline rate along the MRSWTP from south to north shows an accelerating trend.Under the overall trend of global climate warming, the frequencies of cold waves and extreme low-temperature weather along most regions of the MRSWTP have been slowing down, but there have been obvious intensifications observed in some regions since the 21st century. The winter water conveyance flow rate of the project will be further increased to meet the water demands for production, living, and ecology in northern cities. In future winter high-flow water conveyance plans, the impacts of severe cold waves and extreme low temperatures on winter water conveyance should be considered to reduce the risk of ice disasters.
In cold regions, such as high latitudes during winter, rivers and water conveyance channels often experience the phenomenon of freezing under low temperature conditions. During the initial stage of freezing and the subsequent melting stage, ice floes are prone to get stuck in the channels, forming ice jams and dams, which obstruct the flow of water and raise the water level in the channels, thus adversely affecting winter water transfer. Cold waves and extreme low temperatures in the region often cause significant temperature fluctuations, which are the main factors influencing changes in the ice conditions of rivers and channels. The Middle Route of South-to-North Water Transfers Project (MRSWTP) spans multiple latitudes, and the areas north of the Yellow River are affected by ice conditions to varying degrees every year during winter operations. Therefore, analyzing the spatiotemporal variations of cold waves and regional extreme low temperatures along the MRSWTP is of great significance for ice disaster prevention, winter water transportation scheduling, and other related issues.Based on the daily minimum and maximum air temperature data of meteorological stations within a width of 40 km along the route from the head of Taocha Drainage Canal to the Beijuma Culvert of the MRSWTP from 1960 to 2020, the occurrences of cold waves and five extreme cold climate indices were calculated. The Sen’s slope estimator method was employed to analyze their trends. Additionally, the spatial variations of the five extreme climate indices were analyzed using the inverse distance weighting spatial interpolation method based on temperature data from 56 meteorological stations.The results show that among the nine typical weather stations selected, the frequency of cold waves in seven weather stations decreased from 1960 to 2020. The frequency of cold waves in Anyang and Baoding stations showed a downward trend, but since 2000, the number of cold waves has increased significantly. January has the highest frequency of cold waves occurrences, followed by December, February, and November. The regions north of Xingtai show an increasing trend in cold waves occurrence with rising latitudes. As for the extreme climate indices, the minimum value of the annual minimum temperature at the nine meteorological stations generally exhibits an increasing trend from 1960 to 2020. However, since 1990, Baoding station has shown an abnormal trend of not increasing but rather decreasing, while Xingtai and Shijiazhuang stations have remained in a state of stagnation without further increase. The other four extreme climate indices, including frost days (the number of days with a daily minimum temperature below 0 ℃) and freeze days (the number of days with a daily maximum temperature below 0 ℃), generally exhibit different decreasing trends, but some stations show abnormal trends of not decreasing but instead increasing or stagnating. Moreover, it is found that the decline rate of the number of days with a daily minimum temperature below 0 ℃ is faster compared to the decline rate of the number of days with a daily maximum temperature below 0 ℃, indicating a more significant impact of climate change. There is no consistent trend detected among the various climate indices in terms of spatial changes. For freeze days, the decline rate along the MRSWTP from south to north shows an accelerating trend.Under the overall trend of global climate warming, the frequencies of cold waves and extreme low-temperature weather along most regions of the MRSWTP have been slowing down, but there have been obvious intensifications observed in some regions since the 21st century. The winter water conveyance flow rate of the project will be further increased to meet the water demands for production, living, and ecology in northern cities. In future winter high-flow water conveyance plans, the impacts of severe cold waves and extreme low temperatures on winter water conveyance should be considered to reduce the risk of ice disasters.
2023(6):1109-1115.
Abstract:
In the central and northern regions of China, due to the severe cold in winter, the inter-basin water flow will freeze, which will have a negative impact on the Middle Route of South-to-North Water Transfers Project. In order to investigate the relationship between the water temperature and the air temperature along the Middle Route of South-to-North Water Transfers Project, an equidistant sampling method was used to select a sluice gate about 200 km from south to north in the Middle Route of South-to-North Water Transfers Project as the data collection sample. A total of seven sluice gates were selected. The water temperature information of the selected sluice gates and the temperature information of the sluice gate location during the period from November 15, 2022 to February 28, 2023 were collected. The average temperature was used as the analysis object. The average temperature was the average of the highest temperature and the lowest temperature, and the water temperature at 18:00 was used as the the water temperature information of the sluice gate.By comparing the daily average temperature, water temperature, and 15-day moving average temperature of the seven sluice gates, it can be concluded that the trend of water temperature change is similar to the trend of 15-day moving average temperature change, and the fluctuation is consistent. The correlation characteristics of 15-day moving average temperature change and water temperature change along the Middle Route of South-to-North Water Transfers Project were studied. The data obtained by subtracting the temperature difference between the upstream and downstream sections from the water temperature of the sluice gate in the upstream section was compared with the water temperature in the downstream section. The specific steps were as follows: Step 1, the 15-day moving average temperature of the area where the upstream sluice gate was located from the 15-day moving average temperature of the area where the downstream sluice gate was located to obtain the temperature difference between the upstream and downstream regions. Step 2, subtract the temperature difference between the upstream and downstream regions obtained from the first step from the water temperature of the upstream control gate to obtain the second difference. Step 3, compare the second difference with the numerical value of the downstream regulating gate water temperature by drawing a curve.The data obtained by subtracting the 15-day temperature difference along the route from the sluice gate water temperature in the upstream section of the Middle Route of South-to-North Water Transfers Project and the sluice gate water temperature data in the downstream section were calculated using the Pearson correlation coefficient. The Pearson correlation coefficients were all above 0.95, indicating a significant correlation. In winter, the temperature difference from south to north (upstream to downstream) in the inter-basin water transfer project is the main manifestation that reflects the heat loss of the water body. According to the characteristics of the data obtained by subtracting the 15-day air temperature difference along the upstream section from the water temperature in the upstream section and the correlation characteristics of the water temperature data in the downstream section, it can provide a theoretical basis for adjusting the water delivery dispatching strategy during the ice period and preventing freezing disasters for the Middle Route of South-to-North Water Transfers Project.
In the central and northern regions of China, due to the severe cold in winter, the inter-basin water flow will freeze, which will have a negative impact on the Middle Route of South-to-North Water Transfers Project. In order to investigate the relationship between the water temperature and the air temperature along the Middle Route of South-to-North Water Transfers Project, an equidistant sampling method was used to select a sluice gate about 200 km from south to north in the Middle Route of South-to-North Water Transfers Project as the data collection sample. A total of seven sluice gates were selected. The water temperature information of the selected sluice gates and the temperature information of the sluice gate location during the period from November 15, 2022 to February 28, 2023 were collected. The average temperature was used as the analysis object. The average temperature was the average of the highest temperature and the lowest temperature, and the water temperature at 18:00 was used as the the water temperature information of the sluice gate.By comparing the daily average temperature, water temperature, and 15-day moving average temperature of the seven sluice gates, it can be concluded that the trend of water temperature change is similar to the trend of 15-day moving average temperature change, and the fluctuation is consistent. The correlation characteristics of 15-day moving average temperature change and water temperature change along the Middle Route of South-to-North Water Transfers Project were studied. The data obtained by subtracting the temperature difference between the upstream and downstream sections from the water temperature of the sluice gate in the upstream section was compared with the water temperature in the downstream section. The specific steps were as follows: Step 1, the 15-day moving average temperature of the area where the upstream sluice gate was located from the 15-day moving average temperature of the area where the downstream sluice gate was located to obtain the temperature difference between the upstream and downstream regions. Step 2, subtract the temperature difference between the upstream and downstream regions obtained from the first step from the water temperature of the upstream control gate to obtain the second difference. Step 3, compare the second difference with the numerical value of the downstream regulating gate water temperature by drawing a curve.The data obtained by subtracting the 15-day temperature difference along the route from the sluice gate water temperature in the upstream section of the Middle Route of South-to-North Water Transfers Project and the sluice gate water temperature data in the downstream section were calculated using the Pearson correlation coefficient. The Pearson correlation coefficients were all above 0.95, indicating a significant correlation. In winter, the temperature difference from south to north (upstream to downstream) in the inter-basin water transfer project is the main manifestation that reflects the heat loss of the water body. According to the characteristics of the data obtained by subtracting the 15-day air temperature difference along the upstream section from the water temperature in the upstream section and the correlation characteristics of the water temperature data in the downstream section, it can provide a theoretical basis for adjusting the water delivery dispatching strategy during the ice period and preventing freezing disasters for the Middle Route of South-to-North Water Transfers Project.
2023(6):1116-1125.
Abstract:
The Middle Route of South-to-North Water Transfers Project has made a significant contribution to mitigating the water scarcity challenges prevalent in the central and northern regions of China, and in the process of the project scheduling and operation, it usually operates in accordance with the normal water level before the gate. Under the influence of gate regulation, the water level before and after the gate is in a non-stationary process most of the time, so exploring its regular changes has certain limitations and requirements on the monitoring data and research methods. To enhance the precision of water level forecasting within the ambit of the South-to-North Water Transfers Project, the monitoring data and research methodology are improved respectively, with a view to obtaining better prediction results.For a large amount of high-frequency monitoring data, mean filter, sliding mean filter, recursive median mean filter, and sliding wavelet transform are selected for data preprocessing to improve the data quality and enhance the feasibility of data prediction. The data prediction framework leverages two primary neural network models, namely the BP neural network model and LSTM neural network model, and the hydrodynamic model simulation data as the auxiliary support, and selects the pre-gate, and post-gate water level, openness, and flow rate data of the upstream gate itself as the model input factor for prediction. The predictive output factor pertains to the upstream water level of the gate within the subsequent 2 h. The assessment of predictive performance is predicated upon key indicators, namely the coefficient of determination, root-mean-square error, and average absolute error. Indicators compare the single neural network prediction results and network-hydrodynamic combination prediction results and analyze the accuracy and stability of the prediction results.The accuracy of data prediction can be improved after data filtering preprocessing of high-frequency data, and the selection of appropriate water-level data filtering methods can significantly improve the prediction effect. After filtering the data can more clearly show the water level before and after the gate, flow change rule, and the minimum frequency of training data can be selected for 15 minutes of data for filtering and data processing. Constructing BP and LSTM neural networks based on the monitoring data, a comparative analysis is conducted encompassing the number of gate inputs, temporal scales, and data filtering methodologies. The investigation reveals the following insights: The prediction results under the hourly data can already reach the optimal state; The number of gates can be 2 or 3 gates to reach the optimal state, which is related to the frequency of the data; Comparing the prediction results after a variety of filtered data, the recursive median-mean filtering algorithm is the best, and the mean filtering is the worst. The sliding wavelet transform has the worst effect, so it is suggested that the filtering methods are mean filtering and recursive median-mean filtering. The combined hydrodynamic-neural network prediction results are better than the single network prediction results.The computational outcomes prove that high-frequency data preprocessing is a necessary part of data analysis, and the suggested filtering methods mean filter and recursive median-mean filter can be applied in the water condition data processing of the water transfer project. These two filtering methods yield commendable outcomes in data processing. The neural network model necessitates tailoring to the specific parameters corresponding to distinct objects and varying temporal cycles, and after adjusting the parameters, it can better reflect the data change process in a period of time, and the prediction effect is better. Different neural network models have different prediction characteristics, but the prediction accuracy is higher under the condition of sufficient high correlation data. Moreover, the data mechanism dual-drive model can play the advantages of the hydrodynamic model and neural network model at the same time, and the prediction accuracy is higher.
The Middle Route of South-to-North Water Transfers Project has made a significant contribution to mitigating the water scarcity challenges prevalent in the central and northern regions of China, and in the process of the project scheduling and operation, it usually operates in accordance with the normal water level before the gate. Under the influence of gate regulation, the water level before and after the gate is in a non-stationary process most of the time, so exploring its regular changes has certain limitations and requirements on the monitoring data and research methods. To enhance the precision of water level forecasting within the ambit of the South-to-North Water Transfers Project, the monitoring data and research methodology are improved respectively, with a view to obtaining better prediction results.For a large amount of high-frequency monitoring data, mean filter, sliding mean filter, recursive median mean filter, and sliding wavelet transform are selected for data preprocessing to improve the data quality and enhance the feasibility of data prediction. The data prediction framework leverages two primary neural network models, namely the BP neural network model and LSTM neural network model, and the hydrodynamic model simulation data as the auxiliary support, and selects the pre-gate, and post-gate water level, openness, and flow rate data of the upstream gate itself as the model input factor for prediction. The predictive output factor pertains to the upstream water level of the gate within the subsequent 2 h. The assessment of predictive performance is predicated upon key indicators, namely the coefficient of determination, root-mean-square error, and average absolute error. Indicators compare the single neural network prediction results and network-hydrodynamic combination prediction results and analyze the accuracy and stability of the prediction results.The accuracy of data prediction can be improved after data filtering preprocessing of high-frequency data, and the selection of appropriate water-level data filtering methods can significantly improve the prediction effect. After filtering the data can more clearly show the water level before and after the gate, flow change rule, and the minimum frequency of training data can be selected for 15 minutes of data for filtering and data processing. Constructing BP and LSTM neural networks based on the monitoring data, a comparative analysis is conducted encompassing the number of gate inputs, temporal scales, and data filtering methodologies. The investigation reveals the following insights: The prediction results under the hourly data can already reach the optimal state; The number of gates can be 2 or 3 gates to reach the optimal state, which is related to the frequency of the data; Comparing the prediction results after a variety of filtered data, the recursive median-mean filtering algorithm is the best, and the mean filtering is the worst. The sliding wavelet transform has the worst effect, so it is suggested that the filtering methods are mean filtering and recursive median-mean filtering. The combined hydrodynamic-neural network prediction results are better than the single network prediction results.The computational outcomes prove that high-frequency data preprocessing is a necessary part of data analysis, and the suggested filtering methods mean filter and recursive median-mean filter can be applied in the water condition data processing of the water transfer project. These two filtering methods yield commendable outcomes in data processing. The neural network model necessitates tailoring to the specific parameters corresponding to distinct objects and varying temporal cycles, and after adjusting the parameters, it can better reflect the data change process in a period of time, and the prediction effect is better. Different neural network models have different prediction characteristics, but the prediction accuracy is higher under the condition of sufficient high correlation data. Moreover, the data mechanism dual-drive model can play the advantages of the hydrodynamic model and neural network model at the same time, and the prediction accuracy is higher.
2023(6):1126-1133.
Abstract:
The control plan for the segment of the Yangtze-to-Hanjiang River Water Diversion Project will set the control gate at 164 km to avoid the problem of excessive internal pressure in local segments. The rationality of the overall layout of the tunnel line and the layout and shape of the control gate is demonstrated from the perspective of hydrodynamic characteristics.A hybrid model combining a one-dimensional and three-dimensional mathematical model with a physical model was used for relevant research. The one-dimensional water hammer mathematical model is used to analyed the entire hydraulic transition process of the gate opening and closing process. Through optimization calculations, a relatively optimal gate opening and closing process was obtained, while providing boundary conditions for the three-dimensional mathematical and physical models of the control gate segment. A three-dimensional water air two-phase flow mathematical model and a 1:25 scale hydraulic overall physical model are used to simulate and analyze hydraulic indicators such as flow patterns, water surface fluctuations, and pressure distribution on the overflow surface of the gate chamber and regulating pool. At the same time, a control gate discharge capacity curve is provided for a one-dimensional mathematical model.The experimental research results indicate that when the control center hole arc door is opened with a three-stage variable speed process of slow first and then fast, the maximum water hammer pressure value of the entire line can be kept within the allowable range of the regulations; The pressure distribution on the overflow surface of the middle hole is normal, and the energy dissipation of the water in the regulating pool is sufficient. The water surface fluctuation at the inlet front of the lower pressure tunnel is small, and no adverse flow patterns such as suction vortices are observed.The overall plan of adopting segmented layered pressure reduction control in this project is feasible, and the layout and shape of the control gates are reasonable. The research method can be used as a reference for similar projects.
The control plan for the segment of the Yangtze-to-Hanjiang River Water Diversion Project will set the control gate at 164 km to avoid the problem of excessive internal pressure in local segments. The rationality of the overall layout of the tunnel line and the layout and shape of the control gate is demonstrated from the perspective of hydrodynamic characteristics.A hybrid model combining a one-dimensional and three-dimensional mathematical model with a physical model was used for relevant research. The one-dimensional water hammer mathematical model is used to analyed the entire hydraulic transition process of the gate opening and closing process. Through optimization calculations, a relatively optimal gate opening and closing process was obtained, while providing boundary conditions for the three-dimensional mathematical and physical models of the control gate segment. A three-dimensional water air two-phase flow mathematical model and a 1:25 scale hydraulic overall physical model are used to simulate and analyze hydraulic indicators such as flow patterns, water surface fluctuations, and pressure distribution on the overflow surface of the gate chamber and regulating pool. At the same time, a control gate discharge capacity curve is provided for a one-dimensional mathematical model.The experimental research results indicate that when the control center hole arc door is opened with a three-stage variable speed process of slow first and then fast, the maximum water hammer pressure value of the entire line can be kept within the allowable range of the regulations; The pressure distribution on the overflow surface of the middle hole is normal, and the energy dissipation of the water in the regulating pool is sufficient. The water surface fluctuation at the inlet front of the lower pressure tunnel is small, and no adverse flow patterns such as suction vortices are observed.The overall plan of adopting segmented layered pressure reduction control in this project is feasible, and the layout and shape of the control gates are reasonable. The research method can be used as a reference for similar projects.
2023(6):1134-1144.
Abstract:
Large-scale water transfer projects make a considerable contribution to reducing a country's uneven distribution of water resources. The water level between two neighboring pumping stations should be kept as consistent as feasible in an open-channel water transfer project that includes a wide range of hydraulic structures for various purposes to prevent potential channel overflow or drying-up of the pumping station forebay. A sharp change in water level may impair water supply and generate significant hydraulic oscillation. As a result, precise prediction of water levels in front of pumping stations is critical to the normal operation of these pumping stations.The GRA-NARX (grey relationship analysis-nonlinear autoregressive model with exogenous inputs) model is a recurrent dynamic network composed of input delay and feedback memory nodes, with advantageous properties such as more rapid calculation, high generalization performance and high accuracy. The GRA-NARX model based on hyper-parameter automatic calibration is an effective improvement of the GRA-NARX model, which significantly improves the accuracy of water level prediction in front of the Tundian pumping station of the Miyun project in the 2 h short forecast period. However, this model did not consider the water level prediction for different short forecast periods (4 h, 6 h) and long forecast period (12 h). Taking the Hongze pumping station of the Eastern Route of South-to-North Water Transfers Project as an example, the model is used to predict the water level in front of the pumping station for three short forecast periods (2 h, 4 h, 6 h) and one long forecast period (12 h) based on input data at 1 hour and 2 hours intervals, and the prediction results are compared with the GRA-BP (grey relationship analysis backpropagation) model. The results show that the prediction accuracy of the GRA-NARX model with automatic calibration of hyper-parameters is better than that of the GRA-BP model under different forecast periods. The coefficient of association (R), root mean square error (ERMS), and mean absolute error (EMA) of the GRA-NARX model with automatic calibration of hyper-parameters are not significantly different under different forecast periods. When the time interval for inputting data is 1 hour, with a long forecast period of 12 hours, the optimal R is 0.990 03, ERMS is 0.018 m, and EMA is 0.013 m. When the time interval for inputting data is 2 hours, with a forecast period of 12 hours, the optimal R is 0.96985,ERMS is 0.033 m, and EMA is 0.02 m.Since the hyper-parameters of the GRA-NARX neural network are automatically calibrated and the optimal combination of time delay and the number of hidden layer neurons is selected, the GRA-NARX neural network based on the automatic calibration of hyper-parameters under different forecast periods has a good prediction effect on the water level prediction in front of the pumping station, which can meet the water level prediction demand of the pumping station in different forecast periods. Under the same forecast period, when the time interval of inputting data is 1 hour, the prediction results of the GRA-NARX model with hyper-parameter automatic calibration are better than those of the model with inputting data time interval of 2 hours, and the prediction accuracy is high. The findings of the study can be used as the groundwork for estimating the water level in front of pumping stations across different forecast periods.
Large-scale water transfer projects make a considerable contribution to reducing a country's uneven distribution of water resources. The water level between two neighboring pumping stations should be kept as consistent as feasible in an open-channel water transfer project that includes a wide range of hydraulic structures for various purposes to prevent potential channel overflow or drying-up of the pumping station forebay. A sharp change in water level may impair water supply and generate significant hydraulic oscillation. As a result, precise prediction of water levels in front of pumping stations is critical to the normal operation of these pumping stations.The GRA-NARX (grey relationship analysis-nonlinear autoregressive model with exogenous inputs) model is a recurrent dynamic network composed of input delay and feedback memory nodes, with advantageous properties such as more rapid calculation, high generalization performance and high accuracy. The GRA-NARX model based on hyper-parameter automatic calibration is an effective improvement of the GRA-NARX model, which significantly improves the accuracy of water level prediction in front of the Tundian pumping station of the Miyun project in the 2 h short forecast period. However, this model did not consider the water level prediction for different short forecast periods (4 h, 6 h) and long forecast period (12 h). Taking the Hongze pumping station of the Eastern Route of South-to-North Water Transfers Project as an example, the model is used to predict the water level in front of the pumping station for three short forecast periods (2 h, 4 h, 6 h) and one long forecast period (12 h) based on input data at 1 hour and 2 hours intervals, and the prediction results are compared with the GRA-BP (grey relationship analysis backpropagation) model. The results show that the prediction accuracy of the GRA-NARX model with automatic calibration of hyper-parameters is better than that of the GRA-BP model under different forecast periods. The coefficient of association (R), root mean square error (ERMS), and mean absolute error (EMA) of the GRA-NARX model with automatic calibration of hyper-parameters are not significantly different under different forecast periods. When the time interval for inputting data is 1 hour, with a long forecast period of 12 hours, the optimal R is 0.990 03, ERMS is 0.018 m, and EMA is 0.013 m. When the time interval for inputting data is 2 hours, with a forecast period of 12 hours, the optimal R is 0.96985,ERMS is 0.033 m, and EMA is 0.02 m.Since the hyper-parameters of the GRA-NARX neural network are automatically calibrated and the optimal combination of time delay and the number of hidden layer neurons is selected, the GRA-NARX neural network based on the automatic calibration of hyper-parameters under different forecast periods has a good prediction effect on the water level prediction in front of the pumping station, which can meet the water level prediction demand of the pumping station in different forecast periods. Under the same forecast period, when the time interval of inputting data is 1 hour, the prediction results of the GRA-NARX model with hyper-parameter automatic calibration are better than those of the model with inputting data time interval of 2 hours, and the prediction accuracy is high. The findings of the study can be used as the groundwork for estimating the water level in front of pumping stations across different forecast periods.
2023(6):1145-1151,1158.
Abstract:
Plunger control valves are widely applied in water diversion projects, and thus the design of hydraulic characteristics of valves becomes important. Flow path optimization and simulation calculation are two hydraulic characteristics of valves that are mostly studied, while the research on valves setting elevation is scarce. Therefore, it is necessary to optimize the hydraulic characteristics of the valve's internal flow path, determine the reasonable setting elevation of valves, and eliminate cavitation and vibration during valve design.This study focused on improving the operating conditions of valves and determining the reasonable setting elevation of valves, to prolong the service life of valves. The mechanical criterion of hydraulic turbine cavitation was utilized, and the formula for calculating the valves setting elevation was derived. In addition, the hydraulic design of valves was verified by collecting the operating data of the in-line valve and drawing the flow coefficient-opening characteristic curve of a real hydraulic turbine, which was later used to guide the field operation.The results show that the measured flow coefficient is consistent with the designed curve when the opening of the valve is above 45.3%, which verifies the correctness of the hydraulic design of the valve. However, in the small opening section of the valve, the deviation between the measured flow coefficient and the designed curve is slightly larger. In the field test, the valve runs smoothly, and the noise is less than 90 dB (A), with the vibration fluctuating in a small range.The safe and smooth operation of the valve is ensured by optimizing the hydraulic design of the valve and determining the reasonable setting elevation of the valve. The cavitation, vibration, and noise of the valve are reduced, and the service life of the valve is extended. In addition, the field test of valve performance further verifies the rationality of the design of hydraulic characteristics of valves.
Plunger control valves are widely applied in water diversion projects, and thus the design of hydraulic characteristics of valves becomes important. Flow path optimization and simulation calculation are two hydraulic characteristics of valves that are mostly studied, while the research on valves setting elevation is scarce. Therefore, it is necessary to optimize the hydraulic characteristics of the valve's internal flow path, determine the reasonable setting elevation of valves, and eliminate cavitation and vibration during valve design.This study focused on improving the operating conditions of valves and determining the reasonable setting elevation of valves, to prolong the service life of valves. The mechanical criterion of hydraulic turbine cavitation was utilized, and the formula for calculating the valves setting elevation was derived. In addition, the hydraulic design of valves was verified by collecting the operating data of the in-line valve and drawing the flow coefficient-opening characteristic curve of a real hydraulic turbine, which was later used to guide the field operation.The results show that the measured flow coefficient is consistent with the designed curve when the opening of the valve is above 45.3%, which verifies the correctness of the hydraulic design of the valve. However, in the small opening section of the valve, the deviation between the measured flow coefficient and the designed curve is slightly larger. In the field test, the valve runs smoothly, and the noise is less than 90 dB (A), with the vibration fluctuating in a small range.The safe and smooth operation of the valve is ensured by optimizing the hydraulic design of the valve and determining the reasonable setting elevation of the valve. The cavitation, vibration, and noise of the valve are reduced, and the service life of the valve is extended. In addition, the field test of valve performance further verifies the rationality of the design of hydraulic characteristics of valves.
2023(6):1152-1158.
Abstract:
During the construction of the headrace tunnel, water inrush and rock instability often occur when facing unfavorable geological bodies, causing project delays and equipment damage. Grouting has been used as a traditional and effective solution to water blocking and reinforcement to effectively avoid the occurrence of accidents. The grouting material is one of the important factors influencing the grouting effect. To realize the high-performance grouting treatment, a variety of grouting materials such as cement, ultrafine cement, sol-gel, waterglass, epoxy resin, polyurethane, and acrylate have been developed. Among grouting materials, polyurethane has been attracting tremendous attention in terms of its extraordinary properties. More specifically, the isocyanate group (—NCO) in polyurethane reacts with water rapidly, the secondary filling ability for micro-fractures due to carbon dioxide exerted from the reaction between —NCO and water, which is especially suitable for the treatment of water inrush. However, there are some drawbacks of polyurethane such as expensive and low compressive strength, which limits its practical applications. Given the problems such as high cost and low compressive strength of polyurethane grouting materials when it is used in water blocking and reinforcement of unfavorable geological bodies, the composite strategy is an important consideration in the performance improvement of grouting materials, such as PU/cement, and epoxy/cement.Some previous studies have shown that polyurethane/waterglass is an organic-inorganic hybrid material that integrates the advantages of both polyurethane and waterglass but avoid their drawbacks. To date, the highly efficient consolidation of polyurethane and waterglass grouting materials has been achieved. Oil-soluble polyurethane was modified by waterglass and the modified polyurethane was prepared successfully. However, the content of raw materials such as polyphenyl polymethylene polyisocyanate (PAPI), waterglass, and catalyst has an impact on the compressive strength of the modified polyurethane. Therefore, to explore the influence of the content of PAPI, waterglass, and catalyst on the compressive strength of materials, the orthogonal experiment design was used to analyze the influence of different PAPI, waterglass, and catalyst content on the compressive strength of the modified polyurethane, and the significant factors affecting the compressive strength were determined. The structures and properties of the materials were characterized by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR) to understand the influence of microstructure on macro strength. Results showed that the strength of materials was most affected by the content of waterglass, less by the catalyst, and least by the PAPI. When m(PAPI):m(waterglass):m(catalyst)=20∶20∶1, the strength of the curing body and stone body reached 49.5 and 16.5 MPa, respectively, which is superior to other similar products. Further microstructure analysis demonstrated that the surface of the modified polyurethane was uniform without obvious fine crevices, and the phases in grouting materials were interconnected with each other. The characteristic absorption peak near 1050cm?1 gradually increased with the increase of waterglass content, indicating that —NCO reacted with the activated silanol generated from the hydrolysis of waterglass. Inorganic Si—O bond was introduced into the polymer chain segment and formed a stable inorganic-organic interpenetrating network structure, which further improved the compressive strength of the material.In this research, polyurethane was modified by cheap waterglass. This not only reduce the cost but also improve the compressive strength of materials, which is expected to expand the application scale of polyurethane in the water plugging and reinforcement engineering of broken surrounding rock during the construction of the headrace tunnel.
During the construction of the headrace tunnel, water inrush and rock instability often occur when facing unfavorable geological bodies, causing project delays and equipment damage. Grouting has been used as a traditional and effective solution to water blocking and reinforcement to effectively avoid the occurrence of accidents. The grouting material is one of the important factors influencing the grouting effect. To realize the high-performance grouting treatment, a variety of grouting materials such as cement, ultrafine cement, sol-gel, waterglass, epoxy resin, polyurethane, and acrylate have been developed. Among grouting materials, polyurethane has been attracting tremendous attention in terms of its extraordinary properties. More specifically, the isocyanate group (—NCO) in polyurethane reacts with water rapidly, the secondary filling ability for micro-fractures due to carbon dioxide exerted from the reaction between —NCO and water, which is especially suitable for the treatment of water inrush. However, there are some drawbacks of polyurethane such as expensive and low compressive strength, which limits its practical applications. Given the problems such as high cost and low compressive strength of polyurethane grouting materials when it is used in water blocking and reinforcement of unfavorable geological bodies, the composite strategy is an important consideration in the performance improvement of grouting materials, such as PU/cement, and epoxy/cement.Some previous studies have shown that polyurethane/waterglass is an organic-inorganic hybrid material that integrates the advantages of both polyurethane and waterglass but avoid their drawbacks. To date, the highly efficient consolidation of polyurethane and waterglass grouting materials has been achieved. Oil-soluble polyurethane was modified by waterglass and the modified polyurethane was prepared successfully. However, the content of raw materials such as polyphenyl polymethylene polyisocyanate (PAPI), waterglass, and catalyst has an impact on the compressive strength of the modified polyurethane. Therefore, to explore the influence of the content of PAPI, waterglass, and catalyst on the compressive strength of materials, the orthogonal experiment design was used to analyze the influence of different PAPI, waterglass, and catalyst content on the compressive strength of the modified polyurethane, and the significant factors affecting the compressive strength were determined. The structures and properties of the materials were characterized by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR) to understand the influence of microstructure on macro strength. Results showed that the strength of materials was most affected by the content of waterglass, less by the catalyst, and least by the PAPI. When m(PAPI):m(waterglass):m(catalyst)=20∶20∶1, the strength of the curing body and stone body reached 49.5 and 16.5 MPa, respectively, which is superior to other similar products. Further microstructure analysis demonstrated that the surface of the modified polyurethane was uniform without obvious fine crevices, and the phases in grouting materials were interconnected with each other. The characteristic absorption peak near 1050cm?1 gradually increased with the increase of waterglass content, indicating that —NCO reacted with the activated silanol generated from the hydrolysis of waterglass. Inorganic Si—O bond was introduced into the polymer chain segment and formed a stable inorganic-organic interpenetrating network structure, which further improved the compressive strength of the material.In this research, polyurethane was modified by cheap waterglass. This not only reduce the cost but also improve the compressive strength of materials, which is expected to expand the application scale of polyurethane in the water plugging and reinforcement engineering of broken surrounding rock during the construction of the headrace tunnel.
2023(6):1159-1164.
Abstract:
Pumping station equipment will gradually age with the increase of operating time, and the different operating time and installation position of each unit in a pumping station will lead to the difference in the degree of wear of each unit. Therefore, the operating characteristics of different pumping station units may have different degrees of deviation compared with the theoretical curve, which leads to the deviation of the operation scheme calculated by the optimization model of pumping station based on the theoretical curve.Based on the theoretical curve of the pump, the data and mechanism driven parameter identification methods were used to correct the characteristic curve of pumping station unit. The wear of the unit directly affects the operation efficiency of the pump. The efficiency curve of the unit is corrected by polynomial fitting of the measured data. For the correction of the theoretical curve of speed, because the speed of the operating condition points does not change much and the data points are relatively concentrated, the actual working condition can be converted into the operating parameters under different speeds in proportion, and the overall translation of the theoretical curve of speed can be further induced to achieve the correction of the speed curve. On the basis of the corrected results, considering the possible differences between the characteristic curves of each unit, the optimization model of the pumping station considering the difference characteristics of the unit is established. The maximum total operating efficiency of the pumping station is taken as the objective function to satisfy the flow constraint of a single unit, the total flow constraint and the rotation speed factor. The general particle swarm optimization algorithm is used to solve the model. The flow distribution results of each unit are more suitable for the actual output, so as to realize the fine control of the efficient operation and scheduling objectives of the pumping station.Taking Sihong Pumping Station of the East Route of South-to-North Water Transfer Project as an example, after sifting and sorting out the historical operation data, the curve correction and the comparison between the historical scheme and the optimized scheme are carried out. The results show that, compared with the theoretical curve, the deviation of the actual efficiency curve of the pumping device is large, and the characteristic curve before using the correction can not meet the requirement of calculation accuracy. Since the operation time of each unit in Sihong Pumping Station is more balanced, the difference between each unit is not obvious, and the coincidence degree between the modified efficiency curve and the measured data is increased from 0.6 before the correction to 0.99. However, because the cavitation generated by the pump itself will not affect the functional relationship between the unit speed and flow head, the deviation of the actual pumping device speed curve is very small, the consistency between the theoretical speed curve and the measured data reaches 0.99, the average absolute error of the corrected speed curve is 0.23 r/min less than the actual error before the correction. By comparing the historical operation scheme and the optimization scheme without curve correction, it can be found that the optimal distribution scheme based on the equipment characteristic curve correction is closer to the actual operating condition, avoids the flow distribution error compared with the actual operating condition, and effectively improves the problem of high efficiency of the optimized operation scheme based on the theoretical curve calculation. Compared with the historical operation scheme, the average energy consumption of the operation scheme calculated by the optimization model constructed is reduced by 10.1%.To sum up, using the actual operation data to correct the characteristic curve of the pump unit regularly can effectively strengthen the guiding role of the optimal distribution scheme of the pumping station to the actual dispatching.
Pumping station equipment will gradually age with the increase of operating time, and the different operating time and installation position of each unit in a pumping station will lead to the difference in the degree of wear of each unit. Therefore, the operating characteristics of different pumping station units may have different degrees of deviation compared with the theoretical curve, which leads to the deviation of the operation scheme calculated by the optimization model of pumping station based on the theoretical curve.Based on the theoretical curve of the pump, the data and mechanism driven parameter identification methods were used to correct the characteristic curve of pumping station unit. The wear of the unit directly affects the operation efficiency of the pump. The efficiency curve of the unit is corrected by polynomial fitting of the measured data. For the correction of the theoretical curve of speed, because the speed of the operating condition points does not change much and the data points are relatively concentrated, the actual working condition can be converted into the operating parameters under different speeds in proportion, and the overall translation of the theoretical curve of speed can be further induced to achieve the correction of the speed curve. On the basis of the corrected results, considering the possible differences between the characteristic curves of each unit, the optimization model of the pumping station considering the difference characteristics of the unit is established. The maximum total operating efficiency of the pumping station is taken as the objective function to satisfy the flow constraint of a single unit, the total flow constraint and the rotation speed factor. The general particle swarm optimization algorithm is used to solve the model. The flow distribution results of each unit are more suitable for the actual output, so as to realize the fine control of the efficient operation and scheduling objectives of the pumping station.Taking Sihong Pumping Station of the East Route of South-to-North Water Transfer Project as an example, after sifting and sorting out the historical operation data, the curve correction and the comparison between the historical scheme and the optimized scheme are carried out. The results show that, compared with the theoretical curve, the deviation of the actual efficiency curve of the pumping device is large, and the characteristic curve before using the correction can not meet the requirement of calculation accuracy. Since the operation time of each unit in Sihong Pumping Station is more balanced, the difference between each unit is not obvious, and the coincidence degree between the modified efficiency curve and the measured data is increased from 0.6 before the correction to 0.99. However, because the cavitation generated by the pump itself will not affect the functional relationship between the unit speed and flow head, the deviation of the actual pumping device speed curve is very small, the consistency between the theoretical speed curve and the measured data reaches 0.99, the average absolute error of the corrected speed curve is 0.23 r/min less than the actual error before the correction. By comparing the historical operation scheme and the optimization scheme without curve correction, it can be found that the optimal distribution scheme based on the equipment characteristic curve correction is closer to the actual operating condition, avoids the flow distribution error compared with the actual operating condition, and effectively improves the problem of high efficiency of the optimized operation scheme based on the theoretical curve calculation. Compared with the historical operation scheme, the average energy consumption of the operation scheme calculated by the optimization model constructed is reduced by 10.1%.To sum up, using the actual operation data to correct the characteristic curve of the pump unit regularly can effectively strengthen the guiding role of the optimal distribution scheme of the pumping station to the actual dispatching.
2023(6):1165-1173.
Abstract:
The Hanjiang-to-Weihe River Water Diversion Project area has more tectonic development such as folds and ruptures, and a series of long joints and joint-intensive zones have been developed in the area, which are generally low in the north and high in the south, with gullies and ravines, so rockburst disasters and damage to the original support structure are frequently generated in this section. Therefore, the study on the water diversion project geological survey, analysis of the tunnel surrounding rock explosion damage characteristics and damage patterns is necessary to carry out ultra-deep tunnel rock explosion three-dimensional NPR high-stress compensation support system for early warning and prevention of rock explosion disaster.Using on-site investigation and other methods, the geological conditions of the tunnel and the causes of rockburst damage were analyzed, and comparative testing was carried out to design a rockburst monitoring and early warning test scheme for the northern section of the project area, and a three-dimensional NPR high-stress compensatory support system with the microscopic NPR anchors as the core was put forward. The degree of rockburst control of the surrounding rocks under the new support system and its support effect were analyzed through on-site testing.Field test results show that the three-dimensional NPR high-stress compensation support system with microscopic NPR anchors as the core can force the excavated surrounding rock in the north section of the tunnel to return to the three-dimensional stress state from the two-dimensional stress state employing high constant resistance stress compensation. The use of good mechanical properties of microscopic NPR anchors on the surrounding rock with high constant resistance, and fast pre-tensioning of timely active support, resulting in the application of microscopic NPR anchors in the research section of the micro-seismic energy, frequency are significantly reduced, the number and depth of the burst crater is significantly reduced, the surrounding rock is in a stable state, and the effect of the support and rock explosion control is remarkable.Through on-site exploration and related experiments, it can be seen that the north section of the project area is a super-deep tunnel with complex geological conditions, which is affected by the tectonic stress, and the rock in the area is prone to stress concentration and rockburst phenomena, such as spalling, ejecting, and throwing. The use of traditional small deformation anchors and multi-layer steel arch rigid primary support systems can not effectively prevent the rock explosion disaster, resulting in the frequent occurrence of rock explosions. Based on the theory of excavation stress compensation, put forward to the microscopic NPR anchors as the core of the three-dimensional NPR high-stress compensation support system, combined with on-site monitoring data analysis, the project section of the monitoring and early warning test section in the application of microscopic NPR anchors, micro-earthquake energy, frequency is significantly reduced. The integrity of the surrounding rock improves the depth of the explosion pit, the steel arch frame force and deformation are reduced, the rock explosion disaster has been effectively controlled, and the support effect is remarkable.
The Hanjiang-to-Weihe River Water Diversion Project area has more tectonic development such as folds and ruptures, and a series of long joints and joint-intensive zones have been developed in the area, which are generally low in the north and high in the south, with gullies and ravines, so rockburst disasters and damage to the original support structure are frequently generated in this section. Therefore, the study on the water diversion project geological survey, analysis of the tunnel surrounding rock explosion damage characteristics and damage patterns is necessary to carry out ultra-deep tunnel rock explosion three-dimensional NPR high-stress compensation support system for early warning and prevention of rock explosion disaster.Using on-site investigation and other methods, the geological conditions of the tunnel and the causes of rockburst damage were analyzed, and comparative testing was carried out to design a rockburst monitoring and early warning test scheme for the northern section of the project area, and a three-dimensional NPR high-stress compensatory support system with the microscopic NPR anchors as the core was put forward. The degree of rockburst control of the surrounding rocks under the new support system and its support effect were analyzed through on-site testing.Field test results show that the three-dimensional NPR high-stress compensation support system with microscopic NPR anchors as the core can force the excavated surrounding rock in the north section of the tunnel to return to the three-dimensional stress state from the two-dimensional stress state employing high constant resistance stress compensation. The use of good mechanical properties of microscopic NPR anchors on the surrounding rock with high constant resistance, and fast pre-tensioning of timely active support, resulting in the application of microscopic NPR anchors in the research section of the micro-seismic energy, frequency are significantly reduced, the number and depth of the burst crater is significantly reduced, the surrounding rock is in a stable state, and the effect of the support and rock explosion control is remarkable.Through on-site exploration and related experiments, it can be seen that the north section of the project area is a super-deep tunnel with complex geological conditions, which is affected by the tectonic stress, and the rock in the area is prone to stress concentration and rockburst phenomena, such as spalling, ejecting, and throwing. The use of traditional small deformation anchors and multi-layer steel arch rigid primary support systems can not effectively prevent the rock explosion disaster, resulting in the frequent occurrence of rock explosions. Based on the theory of excavation stress compensation, put forward to the microscopic NPR anchors as the core of the three-dimensional NPR high-stress compensation support system, combined with on-site monitoring data analysis, the project section of the monitoring and early warning test section in the application of microscopic NPR anchors, micro-earthquake energy, frequency is significantly reduced. The integrity of the surrounding rock improves the depth of the explosion pit, the steel arch frame force and deformation are reduced, the rock explosion disaster has been effectively controlled, and the support effect is remarkable.
2023(6):1174-1183.
Abstract:
The Yangtze-to-Huaihe River Water Diversion Project is a significant strategic water resources allocation and comprehensive utilization project across river basins and regions. In this project, the pumping station system is characterized by its large scale, complex structure, and wide range of water supply areas. During the long-term service duration, the system faces various uncertainties and risks. When the fault occurs, the normal operation of the system will be affected, which may cause abnormal water supply, and even lead to a series of ecological and social problems, or even casualties. Therefore, the long-term service risk assessment of the cross-basin long-distance water diversion engineering’s pumping station system is crucial to adequately estimate various risks and understand the overall risk level, which is essential for the development of scientific and rational risk management measures.Aiming at the long-term service risk assessment of the pumping station system of the Yangtze-to-Huaihe River Water Diversion Project (Henan Reach), the fault tree analysis method is employed to identify the major long-term service risk sources and corresponding relationships that may impede the normal pumping function, considering the insufficient water lifting efficiency and safety threat to engineering. Based on the categorized long-term service risk factors, considering operational conditions, equipment quality, technological status, and engineering safety, a multidimensional approach is adopted, in which the analytic hierarchy process and expert consultation methods are utilized to determine the evaluation indicators, indicator weights, and risk rating criteria for the long-term service risks of the pumping station system. This establishes an assessment method for the long-term service risks of the pumping station system of the Yangtze-to-Huaihe River Water Diversion Project (Henan Reach).Based on the collected measurements consisting of engineering characteristics and design flood control parameters of the pumping station system in the Yangtze-to-Huaihe River Water Diversion Project (Henan Reach), the developed long-term service risk assessment method is applied to evaluate the long-term service risk of the Yuanqiao pump station, Zhaolou pump station, Shiliang pump station, Houchenlou pressurized pump station and Qiliqiao pressurized pump station. The results indicate that the long-term service risk rates of the pumping stations are all greater than 1 less than or equal to 2. Among them, Houchenlou pressurized pumping station and Qiliqiao pressurized pumping station (Shangqiu unit) have slightly lower risk levels (around 1.33) due to a slightly higher proportion of backup units (around 33%). The risk rates of the other pumping stations are higher, ranging from 1.50 to 1.70. Overall, the risk levels remain relatively low.However, it is worth noting that risk is the result of the combined effect of risk rates and failure consequences. Pumping stations with larger design discharge are bound to have more severe consequences in the event of failure compared to smaller ones. In the Yangtze-to-Huaihe River Water Diversion Project (Henan Reach), the upstream pumping stations have significantly larger design scales than the downstream pumping stations. This characteristic increases the safety risks of the pumping station system. Furthermore, except for the Shangqiu unit and Xiayi unit at Qiliqiao pressurized pumping station, which are in parallel, all other pumping stations in the Yangtze-to-Huaihe River Water Diversion Project (Henan Reach) are in series. Considering that the risk events at each pumping station are independent and once the upstream pump station fails, the downstream series-connected pumping stations will be unable to operate normally, while the parallel-connected pumping stations will remain unaffected. Taking this into account, the risk rate is revised. The results reveal that, except for Yuanqiao pumping station and Zhaolou pumping station, which are located upstream and are less affected, the risk levels of all the other pumping stations increase to a range greater than 2 and less than or equal to 3. Therefore, the spatial difference and structural relationship of the pump station design scale will significantly increase the service risk of the pumping station system, which should be paid more attention in the subsequent risk control and operation management.
The Yangtze-to-Huaihe River Water Diversion Project is a significant strategic water resources allocation and comprehensive utilization project across river basins and regions. In this project, the pumping station system is characterized by its large scale, complex structure, and wide range of water supply areas. During the long-term service duration, the system faces various uncertainties and risks. When the fault occurs, the normal operation of the system will be affected, which may cause abnormal water supply, and even lead to a series of ecological and social problems, or even casualties. Therefore, the long-term service risk assessment of the cross-basin long-distance water diversion engineering’s pumping station system is crucial to adequately estimate various risks and understand the overall risk level, which is essential for the development of scientific and rational risk management measures.Aiming at the long-term service risk assessment of the pumping station system of the Yangtze-to-Huaihe River Water Diversion Project (Henan Reach), the fault tree analysis method is employed to identify the major long-term service risk sources and corresponding relationships that may impede the normal pumping function, considering the insufficient water lifting efficiency and safety threat to engineering. Based on the categorized long-term service risk factors, considering operational conditions, equipment quality, technological status, and engineering safety, a multidimensional approach is adopted, in which the analytic hierarchy process and expert consultation methods are utilized to determine the evaluation indicators, indicator weights, and risk rating criteria for the long-term service risks of the pumping station system. This establishes an assessment method for the long-term service risks of the pumping station system of the Yangtze-to-Huaihe River Water Diversion Project (Henan Reach).Based on the collected measurements consisting of engineering characteristics and design flood control parameters of the pumping station system in the Yangtze-to-Huaihe River Water Diversion Project (Henan Reach), the developed long-term service risk assessment method is applied to evaluate the long-term service risk of the Yuanqiao pump station, Zhaolou pump station, Shiliang pump station, Houchenlou pressurized pump station and Qiliqiao pressurized pump station. The results indicate that the long-term service risk rates of the pumping stations are all greater than 1 less than or equal to 2. Among them, Houchenlou pressurized pumping station and Qiliqiao pressurized pumping station (Shangqiu unit) have slightly lower risk levels (around 1.33) due to a slightly higher proportion of backup units (around 33%). The risk rates of the other pumping stations are higher, ranging from 1.50 to 1.70. Overall, the risk levels remain relatively low.However, it is worth noting that risk is the result of the combined effect of risk rates and failure consequences. Pumping stations with larger design discharge are bound to have more severe consequences in the event of failure compared to smaller ones. In the Yangtze-to-Huaihe River Water Diversion Project (Henan Reach), the upstream pumping stations have significantly larger design scales than the downstream pumping stations. This characteristic increases the safety risks of the pumping station system. Furthermore, except for the Shangqiu unit and Xiayi unit at Qiliqiao pressurized pumping station, which are in parallel, all other pumping stations in the Yangtze-to-Huaihe River Water Diversion Project (Henan Reach) are in series. Considering that the risk events at each pumping station are independent and once the upstream pump station fails, the downstream series-connected pumping stations will be unable to operate normally, while the parallel-connected pumping stations will remain unaffected. Taking this into account, the risk rate is revised. The results reveal that, except for Yuanqiao pumping station and Zhaolou pumping station, which are located upstream and are less affected, the risk levels of all the other pumping stations increase to a range greater than 2 and less than or equal to 3. Therefore, the spatial difference and structural relationship of the pump station design scale will significantly increase the service risk of the pumping station system, which should be paid more attention in the subsequent risk control and operation management.
2023(6):1184-1193,1203.
Abstract:
The water diversion project combined with the construction of pumped storage power stations can achieve multiple functions such as water diversion, energy storage and power generation, and new energy consumption. It is a new model of "water diversion+" exploring the integration of water and energy. Most domestic scholars and experts have proposed innovative models for the integration of the two in terms of concepts, ideas, and route plans, however, a feasible business model is the important foundation for achieving the integrated development of different industries. Therefore, the feasibility of this model is further studied from the perspective of the engineering investment economy. Considering the low return on investment of water diversion projects and the fact that water prices are generally difficult to cover construction and operation costs at the current development stage, the "water diversion+" business model is proposed, aiming to achieve overall balance through multiple project functions and comprehensive benefits and solve the problem of difficult market-oriented operation under the current water price conditions of a single water diversion project.In order to scientifically calculate the economic benefits generated by the new mode of "water diversion+", the method of comparing the cost of single side water division was adopted. Two engineering cases are used, namely, the combination of water division projects with pure pumped storage power stations and non-circulating pumped storage power stations, to calculate the cost of single side water division under the "water diversion+" model from the aspects of annual operating costs, depreciation costs, and interest expenses, comparing the cost of water diversion projects without the use of the "water diversion+" model to obtain comprehensive benefits and propose the main conditions that should be focused on for water energy integration based on their respective characteristics. The calculation results show that after adopting the "water diversion+" model in two different engineering cases, compared to the construction of separate water diversion projects and pumped storage power stations, the comprehensive investment and operating costs of the "water division+" project have been reduced. On the basis of not reducing the self-benefits of the pumped storage power station, the cost of sharing the single water division function has been reduced by 0.32 yuan/m3 and 0.16 yuan/m3, respectively, compared to the construction of separate water diversion projects, The overall balance of comprehensive benefits has been achieved.According to the research results, the water diversion project and pumped storage power station are implemented in a coordinated manner. The project has two major functions: water diversion and energy storage. Under the premise of reasonable control of scale, the overall investment of the project is shared by the service functions of water supply and energy storage. The cost of evenly spreading to a single cubic meter of water volume under certain conditions will be lower than the cost of constructing a separate water diversion project. In fact, it is equivalent to constructing a water diversion project of the same scale at a lower cost, reducing project investment and operating costs, and significantly enhancing the financial capabilities of the project. There are certain conditions for using the "water diversion+" model, and comprehensive consideration should be given to factors such as the construction needs, project scale, development timing, project scheduling, and operating costs of regional pumping and water diversion projects. At the same time, research results can provide new ideas for fully leveraging the economic benefits of the "water diversion+" model.
The water diversion project combined with the construction of pumped storage power stations can achieve multiple functions such as water diversion, energy storage and power generation, and new energy consumption. It is a new model of "water diversion+" exploring the integration of water and energy. Most domestic scholars and experts have proposed innovative models for the integration of the two in terms of concepts, ideas, and route plans, however, a feasible business model is the important foundation for achieving the integrated development of different industries. Therefore, the feasibility of this model is further studied from the perspective of the engineering investment economy. Considering the low return on investment of water diversion projects and the fact that water prices are generally difficult to cover construction and operation costs at the current development stage, the "water diversion+" business model is proposed, aiming to achieve overall balance through multiple project functions and comprehensive benefits and solve the problem of difficult market-oriented operation under the current water price conditions of a single water diversion project.In order to scientifically calculate the economic benefits generated by the new mode of "water diversion+", the method of comparing the cost of single side water division was adopted. Two engineering cases are used, namely, the combination of water division projects with pure pumped storage power stations and non-circulating pumped storage power stations, to calculate the cost of single side water division under the "water diversion+" model from the aspects of annual operating costs, depreciation costs, and interest expenses, comparing the cost of water diversion projects without the use of the "water diversion+" model to obtain comprehensive benefits and propose the main conditions that should be focused on for water energy integration based on their respective characteristics. The calculation results show that after adopting the "water diversion+" model in two different engineering cases, compared to the construction of separate water diversion projects and pumped storage power stations, the comprehensive investment and operating costs of the "water division+" project have been reduced. On the basis of not reducing the self-benefits of the pumped storage power station, the cost of sharing the single water division function has been reduced by 0.32 yuan/m3 and 0.16 yuan/m3, respectively, compared to the construction of separate water diversion projects, The overall balance of comprehensive benefits has been achieved.According to the research results, the water diversion project and pumped storage power station are implemented in a coordinated manner. The project has two major functions: water diversion and energy storage. Under the premise of reasonable control of scale, the overall investment of the project is shared by the service functions of water supply and energy storage. The cost of evenly spreading to a single cubic meter of water volume under certain conditions will be lower than the cost of constructing a separate water diversion project. In fact, it is equivalent to constructing a water diversion project of the same scale at a lower cost, reducing project investment and operating costs, and significantly enhancing the financial capabilities of the project. There are certain conditions for using the "water diversion+" model, and comprehensive consideration should be given to factors such as the construction needs, project scale, development timing, project scheduling, and operating costs of regional pumping and water diversion projects. At the same time, research results can provide new ideas for fully leveraging the economic benefits of the "water diversion+" model.
2023(6):1194-1203.
Abstract:
In order to solve the engineering problem that the high water level in the intensive section of the cross-channel bridge affected the water transport capacity of the project during the period when the operating flow of the Middle Route of the South-to-North Water Transfers Project exceeded the maximum designed flow for the first time in 2020, the 13.233 km section from Shuangji River inverted siphon to Mei River inverted siphon was selected as the test section, and five typical bridges of the test section were selected as the test objects. The numerical simulation and prototype observation test research methods were used to design and study the application effect of the bridge pier guide dome. The basic type of the guide dome was designed according to the hydraulic theory. The 3D hydrodynamic model parameters were calibrated using the prototype observation data of the unguided dome. Meanwhile, the schemes of different guide dome sizes were further compared and selected by numerical simulation, and the optimal scheme was obtained. Through the prototype test, the optimization of the flow pattern and the improvement of the water transport capacity of the test section of five bridges after installation of the guide domes were analyzed and verified.The results showed that after the installation of the guide dome, the flow pattern near the pier of the five bridges was obviously improved, the head loss of the test section was reduced by around 64.4%, the comprehensive roughness was reduced by around 8.0%, and the flow capacity of the test section was increased by around 8.71%, which further verified the reliability of the numerical simulation.The method of bridge pier guide dome design and prototype observation can also be effectively applied to other similar long-distance open channel water transmission projects.
In order to solve the engineering problem that the high water level in the intensive section of the cross-channel bridge affected the water transport capacity of the project during the period when the operating flow of the Middle Route of the South-to-North Water Transfers Project exceeded the maximum designed flow for the first time in 2020, the 13.233 km section from Shuangji River inverted siphon to Mei River inverted siphon was selected as the test section, and five typical bridges of the test section were selected as the test objects. The numerical simulation and prototype observation test research methods were used to design and study the application effect of the bridge pier guide dome. The basic type of the guide dome was designed according to the hydraulic theory. The 3D hydrodynamic model parameters were calibrated using the prototype observation data of the unguided dome. Meanwhile, the schemes of different guide dome sizes were further compared and selected by numerical simulation, and the optimal scheme was obtained. Through the prototype test, the optimization of the flow pattern and the improvement of the water transport capacity of the test section of five bridges after installation of the guide domes were analyzed and verified.The results showed that after the installation of the guide dome, the flow pattern near the pier of the five bridges was obviously improved, the head loss of the test section was reduced by around 64.4%, the comprehensive roughness was reduced by around 8.0%, and the flow capacity of the test section was increased by around 8.71%, which further verified the reliability of the numerical simulation.The method of bridge pier guide dome design and prototype observation can also be effectively applied to other similar long-distance open channel water transmission projects.
2023(6):1204-1212.
Abstract:
As a national major strategic foundation project, the Middle Route of South-to-North Water Transfers Project not only plays a significant social and economic benefits, but also plays a huge ecological and environmental benefits. Although the economic and social benefits of the Middle Route of South-to-North Water Transfers Project are obvious, there is still a lack of systematic understanding and objective and accurate quantitative evaluation of its ecological and environmental benefits and its added value. Since the Middle Route of South-to-North Water Transfers Project was opened, the water source structure of the water-receieving cities has changed significantly, the exploitation of groundwater resources has decreased significantly, and the groundwater level has risen, which has significantly changed the ecosystem services of groundwater. In this context, it is of great significance to accurately and quantitatively assess the change of groundwater ecosystem service value in the water-receiving area before and after the Middle Route of South-to-North Water Transfers Project and to correctly understand the ecological and environmental benefits brought by the project and promote the rational and scientific utilization of the water resources of the project.The service value of groundwater ecosystem refers to the value that groundwater ecosystem provides material, energy and service to human society through various ways. According to the role of ecosystem in human survival and social and economic development, the value of ecosystem services is divided into four categories: product supply, support, regulation and cultural services. At home and abroad, the quantitative evaluation of ecosystem services mainly adopts three methods, namely, the quality evaluation method, the value evaluation method and the energy evaluation method. Based on the characteristics of the Middle Route of South-to-North Water Transfers Project and the water-receiving cities, the value assessment methods, including market value method, alternative cost method and mining loss method are adopted.The water-receiving cities in Henan Province under the Middle Route of South-to-North Water Transfers Project were selected as the typical research area, and the market value method, alternative engineering method and equivalent substitution method were used to evaluate the groundwater ecosystem service value of the cities in Henan Province from 2008 to 2019.The results showed that: (1) Among the 11 water-receiving cities in Henan Province, the highest value of groundwater ecosystem service was found in Zhengzhou City, the most stable changes were found in Pingdingshan City, Luohe City and Xuchang City, and the most drastic changes were found in Hebi City. (2) In 2019, the value of groundwater ecosystem services in Zhengzhou was 21.317 billion yuan, with the highest value of regulation services, followed by support services and supply services, and the lowest social services. Water conservation index accounted for the highest proportion of total value, followed by prevention of land subsidence index, and scientific research and education index accounted for the smallest proportion. (3) The annual average ecosystem service value of water-receiving cities in Henan Province from 2008 to 2019 was 103.037 billion yuan, and the change trend was first decreasing and then increasing. The turning point appeared in 2013, due to the increase of groundwater resources by underground water pressure extraction, groundwater replacement by the Middle Route of South-to-North Water Transfers Project, afforestation and soil and water conservation measures. The research results can provide a reference for the evaluation of eco-environmental benefits and groundwater protection of the Middle Route of South-to-North Water Transfers Project.
As a national major strategic foundation project, the Middle Route of South-to-North Water Transfers Project not only plays a significant social and economic benefits, but also plays a huge ecological and environmental benefits. Although the economic and social benefits of the Middle Route of South-to-North Water Transfers Project are obvious, there is still a lack of systematic understanding and objective and accurate quantitative evaluation of its ecological and environmental benefits and its added value. Since the Middle Route of South-to-North Water Transfers Project was opened, the water source structure of the water-receieving cities has changed significantly, the exploitation of groundwater resources has decreased significantly, and the groundwater level has risen, which has significantly changed the ecosystem services of groundwater. In this context, it is of great significance to accurately and quantitatively assess the change of groundwater ecosystem service value in the water-receiving area before and after the Middle Route of South-to-North Water Transfers Project and to correctly understand the ecological and environmental benefits brought by the project and promote the rational and scientific utilization of the water resources of the project.The service value of groundwater ecosystem refers to the value that groundwater ecosystem provides material, energy and service to human society through various ways. According to the role of ecosystem in human survival and social and economic development, the value of ecosystem services is divided into four categories: product supply, support, regulation and cultural services. At home and abroad, the quantitative evaluation of ecosystem services mainly adopts three methods, namely, the quality evaluation method, the value evaluation method and the energy evaluation method. Based on the characteristics of the Middle Route of South-to-North Water Transfers Project and the water-receiving cities, the value assessment methods, including market value method, alternative cost method and mining loss method are adopted.The water-receiving cities in Henan Province under the Middle Route of South-to-North Water Transfers Project were selected as the typical research area, and the market value method, alternative engineering method and equivalent substitution method were used to evaluate the groundwater ecosystem service value of the cities in Henan Province from 2008 to 2019.The results showed that: (1) Among the 11 water-receiving cities in Henan Province, the highest value of groundwater ecosystem service was found in Zhengzhou City, the most stable changes were found in Pingdingshan City, Luohe City and Xuchang City, and the most drastic changes were found in Hebi City. (2) In 2019, the value of groundwater ecosystem services in Zhengzhou was 21.317 billion yuan, with the highest value of regulation services, followed by support services and supply services, and the lowest social services. Water conservation index accounted for the highest proportion of total value, followed by prevention of land subsidence index, and scientific research and education index accounted for the smallest proportion. (3) The annual average ecosystem service value of water-receiving cities in Henan Province from 2008 to 2019 was 103.037 billion yuan, and the change trend was first decreasing and then increasing. The turning point appeared in 2013, due to the increase of groundwater resources by underground water pressure extraction, groundwater replacement by the Middle Route of South-to-North Water Transfers Project, afforestation and soil and water conservation measures. The research results can provide a reference for the evaluation of eco-environmental benefits and groundwater protection of the Middle Route of South-to-North Water Transfers Project.
2023(6):1213-1222.
Abstract:
The plain reservoir is an important part of the Eastern Route of the South-to-North Water Transfers Project, supplying water resources for residents, industrial production, and agricultural irrigation, and also providing ecological water replenishment for natural water systems such as mudflats, wetlands, and rivers. Evaluating the ecological service benefits of plain reservoirs will not only help management organizations fully understand the reservoirs' operational status but also guide them in improving the ecological functions, thus promoting human well-being in the service areas. To construct an ecological benefit assessment framework consistent with the engineering characteristics, various calculation methods were synthesized to study the ecological functions and comprehensive benefits of plain reservoirs.The ecological service functions of the plain reservoir were sorted out based on the ecosystem services theory. The accounting standards of ecological service functions' value were determined by various methods such as shadow engineering, market value, willingness-to-pay and so on. To further explore the comprehensive benefits provided by plain reservoirs, the interactive relationship between the service functions of the plain reservoir and the ecological and socio-economic systems of the service areas was analyzed. Using rough set theory and hierarchical analysis as weight determination methods, an assessment model was further built. The Datun Reservoir in Dezhou, Shandong Province was taken as a practical case to carry out the applied research.It was found that: The overall service value of Datun Reservoir shows a general upward trend between 2015 and 2021, peaking in 2018, and the total service value reached 236.493 million yuan in 2021. The value of regulating, supplying, supporting, and cultural services has the largest share of supplying services and fluctuates the most due to its relation to water allocation, reaching 117.654 million yuan in 2021, up 88.363 million yuan compared to 29.291 million yuan in 2015. The smallest cultural services value was 21.003 million yuan in 2021. The comprehensive benefits brought by Datun Reservoir to the human well-being in the service area mainly dominated by ecological and economic benefits. The total benefits in 2015 and 2021 were 44.476 and 85.618 million yuan, respectively. The proportion of economic, ecological, and social benefits, showed a stabilizing trend, gradually remaining at 50%, 41%, and 9%.An accounting standard was proposed for the ecological service value of plain reservoirs and ideas were provided for further assessing the comprehensive benefits of human well-being brought by reservoirs to the region, which not only helps to intuitively reflect the operational status of plain reservoirs but also has practical significance in promoting the realization of the functional value and scientific management.
The plain reservoir is an important part of the Eastern Route of the South-to-North Water Transfers Project, supplying water resources for residents, industrial production, and agricultural irrigation, and also providing ecological water replenishment for natural water systems such as mudflats, wetlands, and rivers. Evaluating the ecological service benefits of plain reservoirs will not only help management organizations fully understand the reservoirs' operational status but also guide them in improving the ecological functions, thus promoting human well-being in the service areas. To construct an ecological benefit assessment framework consistent with the engineering characteristics, various calculation methods were synthesized to study the ecological functions and comprehensive benefits of plain reservoirs.The ecological service functions of the plain reservoir were sorted out based on the ecosystem services theory. The accounting standards of ecological service functions' value were determined by various methods such as shadow engineering, market value, willingness-to-pay and so on. To further explore the comprehensive benefits provided by plain reservoirs, the interactive relationship between the service functions of the plain reservoir and the ecological and socio-economic systems of the service areas was analyzed. Using rough set theory and hierarchical analysis as weight determination methods, an assessment model was further built. The Datun Reservoir in Dezhou, Shandong Province was taken as a practical case to carry out the applied research.It was found that: The overall service value of Datun Reservoir shows a general upward trend between 2015 and 2021, peaking in 2018, and the total service value reached 236.493 million yuan in 2021. The value of regulating, supplying, supporting, and cultural services has the largest share of supplying services and fluctuates the most due to its relation to water allocation, reaching 117.654 million yuan in 2021, up 88.363 million yuan compared to 29.291 million yuan in 2015. The smallest cultural services value was 21.003 million yuan in 2021. The comprehensive benefits brought by Datun Reservoir to the human well-being in the service area mainly dominated by ecological and economic benefits. The total benefits in 2015 and 2021 were 44.476 and 85.618 million yuan, respectively. The proportion of economic, ecological, and social benefits, showed a stabilizing trend, gradually remaining at 50%, 41%, and 9%.An accounting standard was proposed for the ecological service value of plain reservoirs and ideas were provided for further assessing the comprehensive benefits of human well-being brought by reservoirs to the region, which not only helps to intuitively reflect the operational status of plain reservoirs but also has practical significance in promoting the realization of the functional value and scientific management.
2023(6):1223-1234.
Abstract:
The Beijing-Tianjin-Hebei-Henan region is the water-receiving area of the Middle Route of the South-to-North Water Transfers Project. Under the new situation, the water supply and consumption issues in the four provinces and cities are directly related to the follow-up project demonstration of the Middle Route of South-to North Water Transfers Project, and even related to the construction of the national water network. Therefore, it is necessary to analyze and judge the current and future situation of water supply and consumption in order to further promote the high-quality development of the follow-up project of the South-to-North Water Transfers Projecct.There are many factors affecting water resource supply and demand analysis, including socio-economic development, water use efficiency, and water resource conditions and so on. On the basis of formulating the planning level year, the trend of economic and social development and the future water use efficiency are analyzed and judged, the quota method is used to predict the water demand, the available water supply is analyzed and simulated when each water supply project meets the operational requirements, the supply and demand analysis, the gap between supply and demand and is explored the decision-making strategies are put forward. The analysis shows that in the face of future water demand, the population will shift from overall driving to regional driving, and the economy will shift from high-speed driving to high-efficiency driving. The reverse driving of water use efficiency will further play an important role, while the supporting role of local water resources will weaken, and there is still a significant shortage of water resources. The main supply-demand contradiction will shift to rural agricultural areas. Considering the expansion of water supply scope and the increase in agricultural water supply tasks in the Middle Route Project, the first phase of the Middle Route Project has achieved results, and after the implementation of the Yangtze River and Han River Diversion Project, there will still be a water shortage of about 4.4-4.9 billion m3 in 2035. It is recommended that the follow-up Middle Route Project should expand energy and increase water sources to solve this problem. The problems such as agricultural water shortage, groundwater overexploitation, and urban water shortage will be included in the overall plan of the South-to-North Water Transfer Project, and the advantages of the Middle Route Project will be fully utilized to systematically solve the water security problems in the Beijing-Tianjin-Hebei-Henan region.The water supply and demand situation of the four provinces and cities, as well as the future water supply and demand issues under the new situation is analyzed, and the solutions are put forward to address the water supply shortage, which has certain reference value for demonstrating the scale and promoting the high-quality development of the follow-up South-to-North Water Transfers Project.
The Beijing-Tianjin-Hebei-Henan region is the water-receiving area of the Middle Route of the South-to-North Water Transfers Project. Under the new situation, the water supply and consumption issues in the four provinces and cities are directly related to the follow-up project demonstration of the Middle Route of South-to North Water Transfers Project, and even related to the construction of the national water network. Therefore, it is necessary to analyze and judge the current and future situation of water supply and consumption in order to further promote the high-quality development of the follow-up project of the South-to-North Water Transfers Projecct.There are many factors affecting water resource supply and demand analysis, including socio-economic development, water use efficiency, and water resource conditions and so on. On the basis of formulating the planning level year, the trend of economic and social development and the future water use efficiency are analyzed and judged, the quota method is used to predict the water demand, the available water supply is analyzed and simulated when each water supply project meets the operational requirements, the supply and demand analysis, the gap between supply and demand and is explored the decision-making strategies are put forward. The analysis shows that in the face of future water demand, the population will shift from overall driving to regional driving, and the economy will shift from high-speed driving to high-efficiency driving. The reverse driving of water use efficiency will further play an important role, while the supporting role of local water resources will weaken, and there is still a significant shortage of water resources. The main supply-demand contradiction will shift to rural agricultural areas. Considering the expansion of water supply scope and the increase in agricultural water supply tasks in the Middle Route Project, the first phase of the Middle Route Project has achieved results, and after the implementation of the Yangtze River and Han River Diversion Project, there will still be a water shortage of about 4.4-4.9 billion m3 in 2035. It is recommended that the follow-up Middle Route Project should expand energy and increase water sources to solve this problem. The problems such as agricultural water shortage, groundwater overexploitation, and urban water shortage will be included in the overall plan of the South-to-North Water Transfer Project, and the advantages of the Middle Route Project will be fully utilized to systematically solve the water security problems in the Beijing-Tianjin-Hebei-Henan region.The water supply and demand situation of the four provinces and cities, as well as the future water supply and demand issues under the new situation is analyzed, and the solutions are put forward to address the water supply shortage, which has certain reference value for demonstrating the scale and promoting the high-quality development of the follow-up South-to-North Water Transfers Project.
2023(6):1235-1249.
Abstract:
The objective of this study is to establish a unified evaluation system for water ecosystem carrying capacity in multiple river basins, which can scientifically analyze, compare, and predict the changes in water ecosystem carrying capacity. This will further enable the proposal of targeted measures for water ecosystem restoration.Principal component analysis (PCA) and entropy weighting method were used to establish the evaluation indicator system. A fuzzy comprehensive evaluation method was introduced to classify the water ecosystem carrying capacity assessment levels. The ARIMA model was utilized to predict the changes in water ecosystem carrying capacity in the seven rivers basins.From 2011 to 2021, the water ecosystem carrying capacity in the seven rivers basins was generally at an overloaded level. Among them, the Fen River basin showed a significant upward trend, reaching the level of basic sustainability. The remaining basins exhibited insignificant changes in water ecosystem carrying capacity and were classified as generally overloaded. Through the analysis of the contribution rates of evaluation indicators, it was found that the water environmental index and water resources index had a significant impact on the water ecosystem carrying capacity in the selected basins. The ARIMA prediction results indicate that from 2022 to 2031, the water ecosystem carrying capacity of the Fen River, Shushui River, and Qin (Dan) River will continue to increase, leading to an overall improvement in the carrying capacity of each basin.The unified evaluation system in multiple river basins provides a scientific assessment of the water ecosystem carrying capacity of the seven rivers basins in Shanxi Province. Additionally, the ARIMA model proves to be a suitable tool for predicting future trends in water ecosystem carrying capacity changes across multiple river basins.
The objective of this study is to establish a unified evaluation system for water ecosystem carrying capacity in multiple river basins, which can scientifically analyze, compare, and predict the changes in water ecosystem carrying capacity. This will further enable the proposal of targeted measures for water ecosystem restoration.Principal component analysis (PCA) and entropy weighting method were used to establish the evaluation indicator system. A fuzzy comprehensive evaluation method was introduced to classify the water ecosystem carrying capacity assessment levels. The ARIMA model was utilized to predict the changes in water ecosystem carrying capacity in the seven rivers basins.From 2011 to 2021, the water ecosystem carrying capacity in the seven rivers basins was generally at an overloaded level. Among them, the Fen River basin showed a significant upward trend, reaching the level of basic sustainability. The remaining basins exhibited insignificant changes in water ecosystem carrying capacity and were classified as generally overloaded. Through the analysis of the contribution rates of evaluation indicators, it was found that the water environmental index and water resources index had a significant impact on the water ecosystem carrying capacity in the selected basins. The ARIMA prediction results indicate that from 2022 to 2031, the water ecosystem carrying capacity of the Fen River, Shushui River, and Qin (Dan) River will continue to increase, leading to an overall improvement in the carrying capacity of each basin.The unified evaluation system in multiple river basins provides a scientific assessment of the water ecosystem carrying capacity of the seven rivers basins in Shanxi Province. Additionally, the ARIMA model proves to be a suitable tool for predicting future trends in water ecosystem carrying capacity changes across multiple river basins.
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