Volume 22,Issue 4,2024 Table of Contents
2024, 22(4):625-631.
Abstract:
The construction of national water network is recognized as a significant strategic deployment in China. It provides fundamental water security for the comprehensive establishment of a modern socialist country. This initiative is crucial in addressing issues related to water resources, ecology, environment, and disasters and supporting high-quality economic development. Its strategic importance lies not only in solving the uneven spatial and temporal distribution of water resources but also in meeting the new demands and adapting to the evolving economic and social development landscape of China, thereby promoting high-quality development in the water conservancy sector.To advance the construction of the national water network in line with new quality productive forces, key areas for improvement are systematically identified based on an understanding of the essence and developmental requirements of these new forces. The study focused on four dimensions: high-tech, high efficiency, high quality, and green development. Representative research examples were analyzed to gain insights and enhance the national water network construction targeted towards new quality productive forces. These examples included the design of the optimal water resources allocation system for the Yangtze-to-Huaihe River Water Diversion Project, the mainstream water ecology regulation model for the Yangtze River, and the regional water balance diagnostic analysis system. These case studies helped to summarize the practices related to national water network construction and clarified the development needs of new quality productive forces for its construction. The results indicated that in order to ensure that the national water network construction meets the development requirements of new quality productive forces, future research should focus on several areas. These include the development of a national water network construction simulator, the collaborative construction of physical and virtual water networks, modernization efforts to support harmonious coexistence between humans and nature, and the scientific management of the human-water relationship. Conclusively, theoretical support and practical references are provided for the construction of the national network of water resources aimed at new quality productive forces. It also ensures that development is in line with the demands of new quality productive forces by effectively enhancing the construction capabilities of the national network of water resources.
The construction of national water network is recognized as a significant strategic deployment in China. It provides fundamental water security for the comprehensive establishment of a modern socialist country. This initiative is crucial in addressing issues related to water resources, ecology, environment, and disasters and supporting high-quality economic development. Its strategic importance lies not only in solving the uneven spatial and temporal distribution of water resources but also in meeting the new demands and adapting to the evolving economic and social development landscape of China, thereby promoting high-quality development in the water conservancy sector.To advance the construction of the national water network in line with new quality productive forces, key areas for improvement are systematically identified based on an understanding of the essence and developmental requirements of these new forces. The study focused on four dimensions: high-tech, high efficiency, high quality, and green development. Representative research examples were analyzed to gain insights and enhance the national water network construction targeted towards new quality productive forces. These examples included the design of the optimal water resources allocation system for the Yangtze-to-Huaihe River Water Diversion Project, the mainstream water ecology regulation model for the Yangtze River, and the regional water balance diagnostic analysis system. These case studies helped to summarize the practices related to national water network construction and clarified the development needs of new quality productive forces for its construction. The results indicated that in order to ensure that the national water network construction meets the development requirements of new quality productive forces, future research should focus on several areas. These include the development of a national water network construction simulator, the collaborative construction of physical and virtual water networks, modernization efforts to support harmonious coexistence between humans and nature, and the scientific management of the human-water relationship. Conclusively, theoretical support and practical references are provided for the construction of the national network of water resources aimed at new quality productive forces. It also ensures that development is in line with the demands of new quality productive forces by effectively enhancing the construction capabilities of the national network of water resources.
2024, 22(4):632-640.
Abstract:
Water resources are the resource base and lifeblood of economic and social development. The development of water-saving industry is an important task in accelerating the construction of a modern industrial system and promoting the process of Chinese-style modernization. The water-saving industry covers agricultural water-saving irrigation, industrial wastewater treatment, water-saving appliances, pipe network leakage control, sewage recycling, seawater desalination, intelligent water-saving field, etc., which has basically formed the complete industrial chain from research and development design, product equipment manufacturing to engineering construction and service management. The water-saving industry is booming in various fields, and the number of market entities serve this industry is growing year by year.In order to better promote the development of water-saving industry, the development situation of water-saving industry is analyzed in China and the problems faced in the development process are discovered. The main problems are that there is insufficient understanding of the water-saving industry, and the endogenous development momentum has not been fully stimulated; the market concentration of the water-saving industry is low, and the cluster development trend has not yet formed; there is a lack of effective constraints and incentive policies in terms of policy guarantees; technological innovation capabilities are relatively weak, and the investment in water-saving technology research and development is relatively insufficient; fiscal, taxation and financial policy support is insufficient. The reasons are mainly in the following aspects: lagging technological innovation and application; unclear basic situation and industrial development path; small-scale enterprises lacking the guidance of leading enterprises; insufficient finance, taxation and finance support, resulting in a lack of endogenous motivation; incomplete industrial chains and lack of a good ecological environment.In addition, based on the understanding of new quality productive forces and water conservancy new quality productive, the impact of new quality productive forces on the water-saving industry are also discussed. That is, the development of water-saving industry needs to be promoted by new quality productive forces, and the development of new quality productive forces needs the water resources security provided by the water-saving industry.Finally, based on the distinctive feature of new quality productive forces is innovation, which includes innovation at the technology and business models, as well as at the management and systems. In order to comprehensively promote the high-quality development of the water-saving industry, strategies for the development of the water-saving industry in the new era were proposed based on innovation:Promoting the water-saving industry through scientific and technological innovation as scientific and technological innovation is the core factor of developing water conservancy new quality production; Ensuring the development of water-saving industry through system innovation, which is the premise to ensure the healthy development of this industry; Guiding the development of water-saving industry by policy integration because this industry needs the guidance and support of industrial policy; Exploring new commercial and market-oriented industrial paths, and support the development of the water-saving industry through business model innovation; Promoting the development of the water-saving industry through building a complete water-saving industry chain, which is the basis for its long-term development, and industry chain innovation. It is hoped that these measures will promote the high-quality development of water-saving industry.
Water resources are the resource base and lifeblood of economic and social development. The development of water-saving industry is an important task in accelerating the construction of a modern industrial system and promoting the process of Chinese-style modernization. The water-saving industry covers agricultural water-saving irrigation, industrial wastewater treatment, water-saving appliances, pipe network leakage control, sewage recycling, seawater desalination, intelligent water-saving field, etc., which has basically formed the complete industrial chain from research and development design, product equipment manufacturing to engineering construction and service management. The water-saving industry is booming in various fields, and the number of market entities serve this industry is growing year by year.In order to better promote the development of water-saving industry, the development situation of water-saving industry is analyzed in China and the problems faced in the development process are discovered. The main problems are that there is insufficient understanding of the water-saving industry, and the endogenous development momentum has not been fully stimulated; the market concentration of the water-saving industry is low, and the cluster development trend has not yet formed; there is a lack of effective constraints and incentive policies in terms of policy guarantees; technological innovation capabilities are relatively weak, and the investment in water-saving technology research and development is relatively insufficient; fiscal, taxation and financial policy support is insufficient. The reasons are mainly in the following aspects: lagging technological innovation and application; unclear basic situation and industrial development path; small-scale enterprises lacking the guidance of leading enterprises; insufficient finance, taxation and finance support, resulting in a lack of endogenous motivation; incomplete industrial chains and lack of a good ecological environment.In addition, based on the understanding of new quality productive forces and water conservancy new quality productive, the impact of new quality productive forces on the water-saving industry are also discussed. That is, the development of water-saving industry needs to be promoted by new quality productive forces, and the development of new quality productive forces needs the water resources security provided by the water-saving industry.Finally, based on the distinctive feature of new quality productive forces is innovation, which includes innovation at the technology and business models, as well as at the management and systems. In order to comprehensively promote the high-quality development of the water-saving industry, strategies for the development of the water-saving industry in the new era were proposed based on innovation:Promoting the water-saving industry through scientific and technological innovation as scientific and technological innovation is the core factor of developing water conservancy new quality production; Ensuring the development of water-saving industry through system innovation, which is the premise to ensure the healthy development of this industry; Guiding the development of water-saving industry by policy integration because this industry needs the guidance and support of industrial policy; Exploring new commercial and market-oriented industrial paths, and support the development of the water-saving industry through business model innovation; Promoting the development of the water-saving industry through building a complete water-saving industry chain, which is the basis for its long-term development, and industry chain innovation. It is hoped that these measures will promote the high-quality development of water-saving industry.
2024, 22(4):641-650.
Abstract:
As climate change and human activities intensify, the frequency and intensity of heavy rainfall events keep rising, resulting in increased occurrences of extreme flood disasters. Due to the influence of climate change and topography, the flood processes exhibit significant spatial heterogeneity. The Baihe River basin in the upper reaches of the Han River is rich in water resources, but experiences uneven spatial and temporal distribution of rainfall, leading to frequent occurrences of flood disasters. Identifying and simulating representative flood types in the Baihe River basin are of great significance for regional flood management.The daily runoff processes of seven hydrological stations in the Baihe River basin were analyzed for the period from 2007 to 2020. In order to accurately separate flood events by comprehensively considering their magnitude and morphological characteristics, a method that couples with the Peaks Over Threshold and the Sliding Variance Threshold was constructed. A system of behavioral characteristic indicators was constructed to comprehensively describe flood events, considering six dimensions: magnitude, duration, fluctuation variation, peak distribution, peak volume relationship, and morphology. Using this system of behavioral characteristic indicators, the types of floods in Baihe River basin were identified by combining principal component analysis and the K -mean clustering algorithm. Finally, flood events and their behavioral characteristics in the Baihe River basin were simulated by the Time Variant Gain Model.Based on the constructed flood event separation method, 249 flood events were accurately identified in the Baihe River basin. These flood events in the Baihe River basin were classified into four representative types, accounting for 41.0%, 4.0%, 23.3%, and 31.7% of the total flood events, respectively. The four flood types are characterized as follows: continuous short and fat medium floods, extreme variable large floods, sharp and thin medium floods with strong catastrophic effects, and single-peaked flash floods. The spatial distribution of the flood types varied significantly. While floods in mainstreams were dominated by short and moderate-magnitude floods, floods in tributaries were dominated by single-peaked flash floods. This distribution pattern could be attributed to several factors in the tributaries, including smaller basin areas, steep channel slopes, narrow valleys, short flood response times, and the relatively weaker water storage capacity of water control projects. These conditions make it easier for the tributaries to generate rapidly changing, short-duration, and small flash floods, which are challenging to evolve into rare and extreme floods. The Time Variant Gain Model demonstrates high accuracy in capturing diverse characteristics of different flood types. It is particularly effective in simulating the characteristics of sharp and thin medium floods and single-peaked flash floods prevalent in the source and tributaries of the Han River basin. The correlation coefficients of indicators for these two flood types range from 0.78 to 0.98 and 0.80 to 0.99, respectively. The accuracy of results can be attributed to the model, which comprehensively considers basin characteristics, aligning well with the actual conditions.In conclusion, the multidimensional flood behavioral characteristic indicator system can comprehensively depict flood events and the main flood types in the basin. The Time Variant Gain Model performs high accuracy in simulating the behavioral characteristics of different flood types. Valuable insights into the mechanisms of flood formation and the dynamics of flood process changes are provided. The findings are crucial for informing the development of effective flood control planning and management policies.
As climate change and human activities intensify, the frequency and intensity of heavy rainfall events keep rising, resulting in increased occurrences of extreme flood disasters. Due to the influence of climate change and topography, the flood processes exhibit significant spatial heterogeneity. The Baihe River basin in the upper reaches of the Han River is rich in water resources, but experiences uneven spatial and temporal distribution of rainfall, leading to frequent occurrences of flood disasters. Identifying and simulating representative flood types in the Baihe River basin are of great significance for regional flood management.The daily runoff processes of seven hydrological stations in the Baihe River basin were analyzed for the period from 2007 to 2020. In order to accurately separate flood events by comprehensively considering their magnitude and morphological characteristics, a method that couples with the Peaks Over Threshold and the Sliding Variance Threshold was constructed. A system of behavioral characteristic indicators was constructed to comprehensively describe flood events, considering six dimensions: magnitude, duration, fluctuation variation, peak distribution, peak volume relationship, and morphology. Using this system of behavioral characteristic indicators, the types of floods in Baihe River basin were identified by combining principal component analysis and the K -mean clustering algorithm. Finally, flood events and their behavioral characteristics in the Baihe River basin were simulated by the Time Variant Gain Model.Based on the constructed flood event separation method, 249 flood events were accurately identified in the Baihe River basin. These flood events in the Baihe River basin were classified into four representative types, accounting for 41.0%, 4.0%, 23.3%, and 31.7% of the total flood events, respectively. The four flood types are characterized as follows: continuous short and fat medium floods, extreme variable large floods, sharp and thin medium floods with strong catastrophic effects, and single-peaked flash floods. The spatial distribution of the flood types varied significantly. While floods in mainstreams were dominated by short and moderate-magnitude floods, floods in tributaries were dominated by single-peaked flash floods. This distribution pattern could be attributed to several factors in the tributaries, including smaller basin areas, steep channel slopes, narrow valleys, short flood response times, and the relatively weaker water storage capacity of water control projects. These conditions make it easier for the tributaries to generate rapidly changing, short-duration, and small flash floods, which are challenging to evolve into rare and extreme floods. The Time Variant Gain Model demonstrates high accuracy in capturing diverse characteristics of different flood types. It is particularly effective in simulating the characteristics of sharp and thin medium floods and single-peaked flash floods prevalent in the source and tributaries of the Han River basin. The correlation coefficients of indicators for these two flood types range from 0.78 to 0.98 and 0.80 to 0.99, respectively. The accuracy of results can be attributed to the model, which comprehensively considers basin characteristics, aligning well with the actual conditions.In conclusion, the multidimensional flood behavioral characteristic indicator system can comprehensively depict flood events and the main flood types in the basin. The Time Variant Gain Model performs high accuracy in simulating the behavioral characteristics of different flood types. Valuable insights into the mechanisms of flood formation and the dynamics of flood process changes are provided. The findings are crucial for informing the development of effective flood control planning and management policies.
2024, 22(4):651-660.
Abstract:
Joint flood control and optimal scheduling of the cascade reservoirs is a mathematical problem that transforms the complex reservoir scheduling problems in the actual process into abstract optimization problems in the mathematical sense, and transforms these problems into different constraints, and seeks the optimal solution based on these constraints. The combined operation of reservoir groups needs to consider the influence of meteorological, hydrological, hydraulic and other factors, as well as the conflict of interests between upstream and downstream and between multi-functions. Domestic and foreign scholars have used dynamic programming (DP), progressive optimization algorithm (POA), genetic algorithm (GA), and particle swarm algorithm (PSO) and other algorithms to solve the problem. However, the above traditional optimization algorithms still have the problems of poor stability and easy to fall into the local optimal situation, and still need to carry out more in-depth research on the algorithm parameter updating mechanism, search strategy and other aspects.SPADE algorithm is an improved differential evolution algorithm, which uses adaptive success history difference strategy to improve random search efficiency, and adaptive success history parameter update strategy and elite group conservative strategy to improve local convergence speed and global search capability. The algorithm divides all the populations in each generation into elite and base populations in the process of differential variation, the elite population conserves the good genes without adopting the variation strategy, and individuals in the base population randomly select each variation strategy for evolution according to the probability, in which the probability of selecting the differential strategy in each generation is reassigned according to the evolution success rate of each individual produced by the differential strategy, and the flow of the high-quality genes is effectively controlled. A joint flood control optimal scheduling model of a group of terrace reservoirs with the objective function of minimizing the maximum flow rate discharged from the reservoirs is established, combined with the flow constraints and their constraint violation evaluation indexes, and solved by applying the spade algorithm in order to improve the computational efficiency and the flood control and peak shaving ability.The effectiveness of the proposed algorithm is examined through numerical experiments containing 10 test functions and an example experiment of joint flood control optimal scheduling for the middle reaches of Ganjiang River cascade reservoir group. The relevant experimental results show that: In the numerical experiments, the evaluation indexes of the optimal value of the statistical convergence error, the average value, the standard deviation and the number of successes, the evaluation indexes of SPADE algorithm are better than those of SHADE, SADE, GA, PSO and ABC algorithms in eight test functions, and the performance is also more outstanding in the remaining two test functions; In the case experiment of joint flood control optimization of cascade reservoir group in the middle reaches of Ganjiang River with the goal of minimum sum of square discharge of Xiajiang Reservoir, SPADE is obviously superior to SADE, GA and PSO in the index of peak cutting rate by analyzing the historical flood process of 1964 single peak and 1973 multi-peak type. Compared with the two historical flood conditions, SHADE increased by 0.9% and 3.4% respectively, which reduced the peak flood discharge of Ganjiang River. The above analysis fully verifies the superiority of the proposed algorithm, which can be used as an effective tool to solve the cascade reservoir group joint scheduling problem.The above analysis fully verifies the superiority of an improved differential evolutionary algorithm based on the successful history adaptive strategy proposed and its effectiveness in the application of the joint scheduling problem of a group of terrace reservoirs. The combined flood control optimization operation of cascade reservoir groups can rationally utilize the flood control capacity of reservoir groups and effectively play the role of reservoir groups in flood blocking and peak cutting, which is of great significance to reduce the downstream flood control risk.
Joint flood control and optimal scheduling of the cascade reservoirs is a mathematical problem that transforms the complex reservoir scheduling problems in the actual process into abstract optimization problems in the mathematical sense, and transforms these problems into different constraints, and seeks the optimal solution based on these constraints. The combined operation of reservoir groups needs to consider the influence of meteorological, hydrological, hydraulic and other factors, as well as the conflict of interests between upstream and downstream and between multi-functions. Domestic and foreign scholars have used dynamic programming (DP), progressive optimization algorithm (POA), genetic algorithm (GA), and particle swarm algorithm (PSO) and other algorithms to solve the problem. However, the above traditional optimization algorithms still have the problems of poor stability and easy to fall into the local optimal situation, and still need to carry out more in-depth research on the algorithm parameter updating mechanism, search strategy and other aspects.SPADE algorithm is an improved differential evolution algorithm, which uses adaptive success history difference strategy to improve random search efficiency, and adaptive success history parameter update strategy and elite group conservative strategy to improve local convergence speed and global search capability. The algorithm divides all the populations in each generation into elite and base populations in the process of differential variation, the elite population conserves the good genes without adopting the variation strategy, and individuals in the base population randomly select each variation strategy for evolution according to the probability, in which the probability of selecting the differential strategy in each generation is reassigned according to the evolution success rate of each individual produced by the differential strategy, and the flow of the high-quality genes is effectively controlled. A joint flood control optimal scheduling model of a group of terrace reservoirs with the objective function of minimizing the maximum flow rate discharged from the reservoirs is established, combined with the flow constraints and their constraint violation evaluation indexes, and solved by applying the spade algorithm in order to improve the computational efficiency and the flood control and peak shaving ability.The effectiveness of the proposed algorithm is examined through numerical experiments containing 10 test functions and an example experiment of joint flood control optimal scheduling for the middle reaches of Ganjiang River cascade reservoir group. The relevant experimental results show that: In the numerical experiments, the evaluation indexes of the optimal value of the statistical convergence error, the average value, the standard deviation and the number of successes, the evaluation indexes of SPADE algorithm are better than those of SHADE, SADE, GA, PSO and ABC algorithms in eight test functions, and the performance is also more outstanding in the remaining two test functions; In the case experiment of joint flood control optimization of cascade reservoir group in the middle reaches of Ganjiang River with the goal of minimum sum of square discharge of Xiajiang Reservoir, SPADE is obviously superior to SADE, GA and PSO in the index of peak cutting rate by analyzing the historical flood process of 1964 single peak and 1973 multi-peak type. Compared with the two historical flood conditions, SHADE increased by 0.9% and 3.4% respectively, which reduced the peak flood discharge of Ganjiang River. The above analysis fully verifies the superiority of the proposed algorithm, which can be used as an effective tool to solve the cascade reservoir group joint scheduling problem.The above analysis fully verifies the superiority of an improved differential evolutionary algorithm based on the successful history adaptive strategy proposed and its effectiveness in the application of the joint scheduling problem of a group of terrace reservoirs. The combined flood control optimization operation of cascade reservoir groups can rationally utilize the flood control capacity of reservoir groups and effectively play the role of reservoir groups in flood blocking and peak cutting, which is of great significance to reduce the downstream flood control risk.
2024, 22(4):661-671.
Abstract:
To enhance the accuracy of flood forecasting and mitigate prediction errors resulting from the utilization of a single parameter set across the entire hydrological model basin, various corresponding parameters were employed in distinct precipitation scenarios.The research focused on Qingshandian Reservoir, where historical floods were categorized into three levels: large, medium, and small. The Xin'anjiang model and SCE-UA parameter optimization algorithm were employed to investigate the correlation between cumulative rainfall and measured flood peak flow, utilizing the Pearson correlation coefficient. The parameter application index was determined as the maximum 6 h cumulative rainfall exhibiting the strongest correlation. Flood verification and prediction were subsequently performed utilizing the corresponding parameter set.The findings indicated that when floods were not classified, the overall pass rate for 38 floods stood at 92.1%, with an average deterministic coefficient of 0.82. Following the classification of floods into large, medium, and small categories, flood process simulation was conducted. Consequently, the pass rate for large, medium, and small floods reached 100%, accompanied by average deterministic coefficients of 0.92, 0.88, and 0.87, respectively, resulting in an overall average deterministic coefficient of 0.88. The classification demonstrated enhancements in both the pass rate and deterministic coefficient for each individual flood, contributing to an improved fitting effect. Furthermore, an analysis was conducted on the correlation between flood peak flow and maximum rainfall within 1 h, 3 h, 6 h, and 24 h, based on the Pearson correlation coefficient. Results revealed that the maximum 6 h rainfall exhibited the highest Pearson correlation coefficient with flood peak flow. Accordingly, the maximum 6-hour cumulative rainfall during the forecast period was employed as the criterion for determining large, medium, and small parameters.In the actual flood forecasting during the 2021 flood season, all flood forecast results were deemed satisfactory. Notably, four significant and medium-sized floods exhibited a strong fitting degree and high deterministic coefficient. The flood forecasting accuracy, predicated on flood classification, demonstrated a high level of reasonableness and feasibility, thereby offering valuable reference for reservoir flood control.
To enhance the accuracy of flood forecasting and mitigate prediction errors resulting from the utilization of a single parameter set across the entire hydrological model basin, various corresponding parameters were employed in distinct precipitation scenarios.The research focused on Qingshandian Reservoir, where historical floods were categorized into three levels: large, medium, and small. The Xin'anjiang model and SCE-UA parameter optimization algorithm were employed to investigate the correlation between cumulative rainfall and measured flood peak flow, utilizing the Pearson correlation coefficient. The parameter application index was determined as the maximum 6 h cumulative rainfall exhibiting the strongest correlation. Flood verification and prediction were subsequently performed utilizing the corresponding parameter set.The findings indicated that when floods were not classified, the overall pass rate for 38 floods stood at 92.1%, with an average deterministic coefficient of 0.82. Following the classification of floods into large, medium, and small categories, flood process simulation was conducted. Consequently, the pass rate for large, medium, and small floods reached 100%, accompanied by average deterministic coefficients of 0.92, 0.88, and 0.87, respectively, resulting in an overall average deterministic coefficient of 0.88. The classification demonstrated enhancements in both the pass rate and deterministic coefficient for each individual flood, contributing to an improved fitting effect. Furthermore, an analysis was conducted on the correlation between flood peak flow and maximum rainfall within 1 h, 3 h, 6 h, and 24 h, based on the Pearson correlation coefficient. Results revealed that the maximum 6 h rainfall exhibited the highest Pearson correlation coefficient with flood peak flow. Accordingly, the maximum 6-hour cumulative rainfall during the forecast period was employed as the criterion for determining large, medium, and small parameters.In the actual flood forecasting during the 2021 flood season, all flood forecast results were deemed satisfactory. Notably, four significant and medium-sized floods exhibited a strong fitting degree and high deterministic coefficient. The flood forecasting accuracy, predicated on flood classification, demonstrated a high level of reasonableness and feasibility, thereby offering valuable reference for reservoir flood control.
2024, 22(4):672-683.
Abstract:
In the case of global warming, it was established that the amount of uncertainty is growing with regard to droughts. Due to this, different parts of the world experience different types of drought and different measures when it comes to the recovery process of drought, leading to great losses in agriculture. Hence, it is momentous for agricultural droughts to be explored in more depth and to look for proper ways to handle them. Convolutional neural networks (CNN) provide high stability and generalization capability because of the parameter sharing and sparse connection, which decrease the number of parameters for weights and bias respectively. However, they highly depend on the selection of the learning rate (η) to decide their efficiency. Genetic algorithms (GA) have a strong attribute of global search and therefore can be used to optimize functions that are nonlinear and unbalanced and those that comprise of multi-peak; the results obtained in practice have proven to be very efficient. Hence, the use of a CNN model optimized by a GA-CNN to assess the population’s drought resilience. The conceptual framework and analysis of the distribution of water resources in relation to the agricultural economic development of the studied region allowed choosing the following 11 indicators to estimate the level of agricultural drought risk. Thus, applying the principles of the GA-CNN model, the level of drought resilience of the study area was determined for 2010-2021. To find the driving forces of the time evolution of resilience, the entropy method was applied. The results show that during the study period, the agricultural drought resilience of Nehe City was on a rising-triangle course. The temporal change in the agricultural drought resilience in the study area was affected by forest coverage, grain yield per unit area, per capita water resources. With reference to the benchmarks using CNN and SVM, the GA-CNN model offered a decrease in the value of EMA by 23.51% and 32.36%, ERMS by 14.42% and 25.32%, and increase in R2 by 0.08% and 1.08%, respectively. This means that in the areas of fit, ability to adapt, stability and reliability, and the assessment of the model, GA-CNN performs better as compared to others.Based on the main constraints of drought resilience in the study area mentioned above, future research and development strategies should target the reduction of available water supply, the improvement of food productivity, and the rise of forest cover. To sum up, proper management of agricultural water resources, increasing the production capacity of food, effective protection of forests, as well as the greatest possible use of forest resource potentiality, is critical for increasing stable and promising agricultural drought resistance. These measures will also be of help in the diffusion of improvement to neighboring areas and assisting in a mutually beneficial augmentation of the agricultural regions for drought incidences.
In the case of global warming, it was established that the amount of uncertainty is growing with regard to droughts. Due to this, different parts of the world experience different types of drought and different measures when it comes to the recovery process of drought, leading to great losses in agriculture. Hence, it is momentous for agricultural droughts to be explored in more depth and to look for proper ways to handle them. Convolutional neural networks (CNN) provide high stability and generalization capability because of the parameter sharing and sparse connection, which decrease the number of parameters for weights and bias respectively. However, they highly depend on the selection of the learning rate (η) to decide their efficiency. Genetic algorithms (GA) have a strong attribute of global search and therefore can be used to optimize functions that are nonlinear and unbalanced and those that comprise of multi-peak; the results obtained in practice have proven to be very efficient. Hence, the use of a CNN model optimized by a GA-CNN to assess the population’s drought resilience. The conceptual framework and analysis of the distribution of water resources in relation to the agricultural economic development of the studied region allowed choosing the following 11 indicators to estimate the level of agricultural drought risk. Thus, applying the principles of the GA-CNN model, the level of drought resilience of the study area was determined for 2010-2021. To find the driving forces of the time evolution of resilience, the entropy method was applied. The results show that during the study period, the agricultural drought resilience of Nehe City was on a rising-triangle course. The temporal change in the agricultural drought resilience in the study area was affected by forest coverage, grain yield per unit area, per capita water resources. With reference to the benchmarks using CNN and SVM, the GA-CNN model offered a decrease in the value of EMA by 23.51% and 32.36%, ERMS by 14.42% and 25.32%, and increase in R2 by 0.08% and 1.08%, respectively. This means that in the areas of fit, ability to adapt, stability and reliability, and the assessment of the model, GA-CNN performs better as compared to others.Based on the main constraints of drought resilience in the study area mentioned above, future research and development strategies should target the reduction of available water supply, the improvement of food productivity, and the rise of forest cover. To sum up, proper management of agricultural water resources, increasing the production capacity of food, effective protection of forests, as well as the greatest possible use of forest resource potentiality, is critical for increasing stable and promising agricultural drought resistance. These measures will also be of help in the diffusion of improvement to neighboring areas and assisting in a mutually beneficial augmentation of the agricultural regions for drought incidences.
2024, 22(4):684-696.
Abstract:
Irrigation districts usually have characteristics of a high water demand and low water use efficiency, and irrational canal system transmission and distribution schemes lead to water waste, further aggravating the contradiction between water supply and demand in irrigation districts. The optimal water distribution model of canal system should provide scientific and effective methods and tools for formulating optimal water distribution schemes of canal system to cope with future climate change, so as to support the efficient allocation of water resources in irrigation districts.Based on this, the Changgang Irrigation District of Heilongjiang Province is taken as the research area, and a multi-objective model for optimizing water distribution of irrigation canal system is proposed based on the whole process of water transmission loss. The model fully considers the water balance, irrigation time, irrigation water volume and canal water conveyance capacity between different canal sections in the main canal system of the irrigation district, and takes into account the three objectives of water saving, timeliness and fairness in the process of water transmission and distribution in the canal system of the irrigation district. At the same time, the Random Forest model was used to predict the water supply and demand of the irrigation district under future climate change scenarios, which was used as a model input to accurately calculate the loss of canal transmission, and to obtain an objective and practical optimal water distribution scheme for the canal system in Changgang Irrigation District.The results showed that the proportion of water loss from transmission and distribution to the total water loss from transmission and distribution of the upper channel in different canal sections of the upper channel within the same fertility stage was significantly differentiated, and the first canal section of the upper channel close to the head of the canal within any fertility stage accounted for the largest proportion of water loss from transmission and distribution. Through the canal system optimization water distribution model, the total amount of canal system water transmission and distribution in Changgang Irrigation District during the whole crop fertility stage was 2,305,100 m3, the total water distribution time was 494.32 h, and the total amount of water loss in transmission and distribution was 86,600 m3, which was 24.89% less than the amount of water lost in transmission and distribution calculated by the empirical coefficient method in the irrigation district, and it significantly improved the efficiency of water transmission and distribution. When planning and constructing high-standard seepage control facilities, it is suggested that the competent authority of the irrigation district may give priority to the construction of canal section 1, canal section 2, canal section 3 and canal section 6 of the upper channel and the six, ten and eleven branches of the lower channel to optimize the allocation of water resources in the irrigation district and to reduce the loss of water transmission.It is shown that the model helps to provide scientific and reasonable canal system water distribution scheme, realizes the synergistic enhancement of water conservation, timeliness and fairness in the process of canal system water transmission and distribution in the irrigation district, and can be applied to other water-scarce irrigation districts, so as to provide decision-making support for comprehensively enhancing the capacity of water resources management and the level of refined management in irrigation districts.
Irrigation districts usually have characteristics of a high water demand and low water use efficiency, and irrational canal system transmission and distribution schemes lead to water waste, further aggravating the contradiction between water supply and demand in irrigation districts. The optimal water distribution model of canal system should provide scientific and effective methods and tools for formulating optimal water distribution schemes of canal system to cope with future climate change, so as to support the efficient allocation of water resources in irrigation districts.Based on this, the Changgang Irrigation District of Heilongjiang Province is taken as the research area, and a multi-objective model for optimizing water distribution of irrigation canal system is proposed based on the whole process of water transmission loss. The model fully considers the water balance, irrigation time, irrigation water volume and canal water conveyance capacity between different canal sections in the main canal system of the irrigation district, and takes into account the three objectives of water saving, timeliness and fairness in the process of water transmission and distribution in the canal system of the irrigation district. At the same time, the Random Forest model was used to predict the water supply and demand of the irrigation district under future climate change scenarios, which was used as a model input to accurately calculate the loss of canal transmission, and to obtain an objective and practical optimal water distribution scheme for the canal system in Changgang Irrigation District.The results showed that the proportion of water loss from transmission and distribution to the total water loss from transmission and distribution of the upper channel in different canal sections of the upper channel within the same fertility stage was significantly differentiated, and the first canal section of the upper channel close to the head of the canal within any fertility stage accounted for the largest proportion of water loss from transmission and distribution. Through the canal system optimization water distribution model, the total amount of canal system water transmission and distribution in Changgang Irrigation District during the whole crop fertility stage was 2,305,100 m3, the total water distribution time was 494.32 h, and the total amount of water loss in transmission and distribution was 86,600 m3, which was 24.89% less than the amount of water lost in transmission and distribution calculated by the empirical coefficient method in the irrigation district, and it significantly improved the efficiency of water transmission and distribution. When planning and constructing high-standard seepage control facilities, it is suggested that the competent authority of the irrigation district may give priority to the construction of canal section 1, canal section 2, canal section 3 and canal section 6 of the upper channel and the six, ten and eleven branches of the lower channel to optimize the allocation of water resources in the irrigation district and to reduce the loss of water transmission.It is shown that the model helps to provide scientific and reasonable canal system water distribution scheme, realizes the synergistic enhancement of water conservation, timeliness and fairness in the process of canal system water transmission and distribution in the irrigation district, and can be applied to other water-scarce irrigation districts, so as to provide decision-making support for comprehensively enhancing the capacity of water resources management and the level of refined management in irrigation districts.
2024, 22(4):697-907.
Abstract:
Global warming has profoundly changed the pattern of snow cover in the middle latitudes. In order to explore the effect of snow cover change on the water-soluble salinity of farmland black soil in the northeast black soil region, the method of artificial snow removal was adopted in the field, and the snow removal test group (Bare Ground) and the natural snow control group (Normal Ground) respectively were set up. The content changes of 7 kinds of water-soluble salt components (Na+, K+, Ca2+, Mg2+, Cl?, SO42?, HCO3?) in two groups of 0-30 cm farmland black soil were studied.The test results showed that the total salt content of soil was significantly reduced by snow removal during the snow cover period, and the average salt content of group B and group N increased by 107.22 and 129.54 mg/kg, respectively, compared with the beginning of the test period. The contents of Na+, Ca2+, Mg2+and HCO3? were significantly affected by the temperature during the snow cover period, and the four salt components in group B were increased by 10.47%, ?5.79%, ?10.29% and ?7.60%, respectively, compared with group N. The total amount of soil salt in group B and group N was basically the same during the snowmelt period, and the moisture content in this period had a significant impact on the contents of Na+, Mg2+ and HCO3?. The three salt components in group B soil increased by 16.33%, ?33.60% and ?10.38%, respectively, compared with group N. During the experiment period, the contents of HCO3? and bivalent cations (Ca2+ and Mg2+) in the soil were significantly reduced, while the contents of monovalent cations (Na+, K+) and two acid ions (Cl? and SO42?) were significantly increased under the snow removal treatment. HCO3? has the highest effect on the total salt content, and the decrease of HCO3? content caused by snow removal will lead to the decrease of soil pH value by 0.04 and 0.03 in the snow cover period and the snow melt period, respectively.In general, the removal of snow in winter redistributed the salt content of the farmland black soil before the crop growing season in Northeast China, which caused the decrease of soil alkalinity and adversely affected the flocculation state of soil particles. Through studying the effect of snow removal on the water-soluble salt content of farmland black soil in the northeast black soil region, a scientific basis is provided for exploring the change of black soil salt dynamics and environmental stability under the influence of climate warming.
Global warming has profoundly changed the pattern of snow cover in the middle latitudes. In order to explore the effect of snow cover change on the water-soluble salinity of farmland black soil in the northeast black soil region, the method of artificial snow removal was adopted in the field, and the snow removal test group (Bare Ground) and the natural snow control group (Normal Ground) respectively were set up. The content changes of 7 kinds of water-soluble salt components (Na+, K+, Ca2+, Mg2+, Cl?, SO42?, HCO3?) in two groups of 0-30 cm farmland black soil were studied.The test results showed that the total salt content of soil was significantly reduced by snow removal during the snow cover period, and the average salt content of group B and group N increased by 107.22 and 129.54 mg/kg, respectively, compared with the beginning of the test period. The contents of Na+, Ca2+, Mg2+and HCO3? were significantly affected by the temperature during the snow cover period, and the four salt components in group B were increased by 10.47%, ?5.79%, ?10.29% and ?7.60%, respectively, compared with group N. The total amount of soil salt in group B and group N was basically the same during the snowmelt period, and the moisture content in this period had a significant impact on the contents of Na+, Mg2+ and HCO3?. The three salt components in group B soil increased by 16.33%, ?33.60% and ?10.38%, respectively, compared with group N. During the experiment period, the contents of HCO3? and bivalent cations (Ca2+ and Mg2+) in the soil were significantly reduced, while the contents of monovalent cations (Na+, K+) and two acid ions (Cl? and SO42?) were significantly increased under the snow removal treatment. HCO3? has the highest effect on the total salt content, and the decrease of HCO3? content caused by snow removal will lead to the decrease of soil pH value by 0.04 and 0.03 in the snow cover period and the snow melt period, respectively.In general, the removal of snow in winter redistributed the salt content of the farmland black soil before the crop growing season in Northeast China, which caused the decrease of soil alkalinity and adversely affected the flocculation state of soil particles. Through studying the effect of snow removal on the water-soluble salt content of farmland black soil in the northeast black soil region, a scientific basis is provided for exploring the change of black soil salt dynamics and environmental stability under the influence of climate warming.
2024, 22(4):708-718.
Abstract:
Agricultural non-point source pollution compromises the security of water and soil resources in China, making it imperative to understand the distribution characteristics of such pollution in specific areas to effectively implement environmental protection measures. As a principal grain-producing area in China, the Sanjiang Plain is critical for ensuring national food security and stability, boasting an annual grain output of approximately 2.5×107t. However, the body of research addressing the use and pollution characteristics of neonicotinoid insecticides in this region remains limited, with inadequate in systematic studies on the residual mass fraction and distribution of these substances in the soil.This study concentrates on the Sanjiang Plain, a significant grain-producing region in China, and selects the widely used neonicotinoid insecticide, imidacloprid, as the subject for conducting related inventory research. An estimation method for neonicotinoid insecticides was formulated and applied to calculate the thiamethoxam use in the Sanjiang Plain from 2011 to 2020. Additionally, rice, maize, and soybean cultivation areas in the Sanjiang Plain served as surrogate data to establish a gridded use inventory of thiamethoxam in the region with a resolution of 10 km × 10 km. Furthermore, the usage inventory served as input data, and an enhanced simplified gridded pesticide emission and residue model, which thoroughly incorporated environmental behavior processes, was employed to develop residue and soil mass fraction inventories. Finally, the risk quotient methodology was employed to assess the potential ecological risks of neonicotinoid pesticides in soil to non-target species.The results showed that: (1) the cumulative usage of thiamethoxam in the Sanjiang Plain from 2011 to 2020 was about 86 t, and the loss through spray drift and runoff discharge was about 1.3 t. In terms of spatial distribution, hotspots of thiamethoxam usage were identified in the central, southwestern, and southeastern parts of the Sanjiang Plain. In contrast, the northwestern, eastern, and southern parts of the cultivated land, being smaller in area, exhibited a lower demand for pesticides. (2) Years of consistent usage resulted in the accumulation of neonicotinoid insecticides in the soil, with the cumulative residue of thiamethoxam in the Sanjiang Plain's soil increasing from 7.0 to 13.1 tons between 2011 and 2020, marking an approximate 0.8-fold increase. To address potential uncertainties in the thiamethoxam residue calculation process, an analysis of these uncertainties and the sensitivity of the parameters is undertook, aiming to identify the primary factors influencing residue levels and to refine and optimize the calculation process, thereby reducing result uncertainties. (3) Spatial mass fraction of neonicotinoid insecticides in the surface soil of each grid were estimated, based on residue levels, ranging from 0 to 3.45 ng/g. To assess the accuracy of the residue inventory established herein, the simulated values were juxtaposed with actual soil monitoring concentration data, affirming the inventory's reliability. (4) Typical organisms of the Sanjiang Plain are already under threat from soil thiamethoxam residues, and the regional extent of this risk, along with the potential threat to the ecosystem, is gradually escalating, necessitating consideration.The establishment of the usage inventory and the refined emission/residue inventory model effectively elucidates the spatial and temporal dynamics of pesticide use and residue. This provides fundamental data and a scientific foundation for formulating pesticide pollution control strategies, relevant policies, and action plans, and also offers a technical methodology for developing a gridded pesticide inventory.
Agricultural non-point source pollution compromises the security of water and soil resources in China, making it imperative to understand the distribution characteristics of such pollution in specific areas to effectively implement environmental protection measures. As a principal grain-producing area in China, the Sanjiang Plain is critical for ensuring national food security and stability, boasting an annual grain output of approximately 2.5×107t. However, the body of research addressing the use and pollution characteristics of neonicotinoid insecticides in this region remains limited, with inadequate in systematic studies on the residual mass fraction and distribution of these substances in the soil.This study concentrates on the Sanjiang Plain, a significant grain-producing region in China, and selects the widely used neonicotinoid insecticide, imidacloprid, as the subject for conducting related inventory research. An estimation method for neonicotinoid insecticides was formulated and applied to calculate the thiamethoxam use in the Sanjiang Plain from 2011 to 2020. Additionally, rice, maize, and soybean cultivation areas in the Sanjiang Plain served as surrogate data to establish a gridded use inventory of thiamethoxam in the region with a resolution of 10 km × 10 km. Furthermore, the usage inventory served as input data, and an enhanced simplified gridded pesticide emission and residue model, which thoroughly incorporated environmental behavior processes, was employed to develop residue and soil mass fraction inventories. Finally, the risk quotient methodology was employed to assess the potential ecological risks of neonicotinoid pesticides in soil to non-target species.The results showed that: (1) the cumulative usage of thiamethoxam in the Sanjiang Plain from 2011 to 2020 was about 86 t, and the loss through spray drift and runoff discharge was about 1.3 t. In terms of spatial distribution, hotspots of thiamethoxam usage were identified in the central, southwestern, and southeastern parts of the Sanjiang Plain. In contrast, the northwestern, eastern, and southern parts of the cultivated land, being smaller in area, exhibited a lower demand for pesticides. (2) Years of consistent usage resulted in the accumulation of neonicotinoid insecticides in the soil, with the cumulative residue of thiamethoxam in the Sanjiang Plain's soil increasing from 7.0 to 13.1 tons between 2011 and 2020, marking an approximate 0.8-fold increase. To address potential uncertainties in the thiamethoxam residue calculation process, an analysis of these uncertainties and the sensitivity of the parameters is undertook, aiming to identify the primary factors influencing residue levels and to refine and optimize the calculation process, thereby reducing result uncertainties. (3) Spatial mass fraction of neonicotinoid insecticides in the surface soil of each grid were estimated, based on residue levels, ranging from 0 to 3.45 ng/g. To assess the accuracy of the residue inventory established herein, the simulated values were juxtaposed with actual soil monitoring concentration data, affirming the inventory's reliability. (4) Typical organisms of the Sanjiang Plain are already under threat from soil thiamethoxam residues, and the regional extent of this risk, along with the potential threat to the ecosystem, is gradually escalating, necessitating consideration.The establishment of the usage inventory and the refined emission/residue inventory model effectively elucidates the spatial and temporal dynamics of pesticide use and residue. This provides fundamental data and a scientific foundation for formulating pesticide pollution control strategies, relevant policies, and action plans, and also offers a technical methodology for developing a gridded pesticide inventory.
2024, 22(4):719-727.
Abstract:
The irrigation water effective utilization coefficient serves as a crucial indicator to assess the efficacy of agricultural irrigation, as well as a vital component in implementing a stringent water resource management system. However, until now, there has been a lack of efficient and accurate methods for predicting the irrigation water effective utilization coefficient. In light of this, a novel prediction approach was presented for the irrigation water effective utilization coefficient.Initially, a stepwise regression analysis was employed to determine the significance of each factor contributing to the coefficient, with the water-saving irrigation area being identified as the primary factor influencing the irrigation water effective utilization coefficient. Secondly, the stepwise regression model was selected considering the key factors, and the GM(1,1) model and Logistic growth model were selected considering the time series. Finally, it was constructed of a variable weight combination model with enhanced prediction accuracy, which utilized the three weight values derived from the error values of the stepwise regression method, GM (1,1) model and Logistic growth model. The prediction error revealed that the curve of the variable weight model aligns well with the measure results curve, demonstrating a prediction accuracy that was markedly superior to that of the individual models, making it suitable for predicting the irrigation water effective utilization coefficient.The variable weight combination model was utilized to predict and analyze the irrigation water effective utilization coefficient in Guangdong Province from 2023 to 2035. The prediction result indicated that the forecast value of the irrigation water effective utilization coefficient will reach 0.679 2 in Guangdong Province by 2035.The theoretical reference is provided for the planning and management system of agricultural water resources. It is of great significance to the upgrading and modernization of irrigation districts in China as well as to the reform of agricultural water prices.
The irrigation water effective utilization coefficient serves as a crucial indicator to assess the efficacy of agricultural irrigation, as well as a vital component in implementing a stringent water resource management system. However, until now, there has been a lack of efficient and accurate methods for predicting the irrigation water effective utilization coefficient. In light of this, a novel prediction approach was presented for the irrigation water effective utilization coefficient.Initially, a stepwise regression analysis was employed to determine the significance of each factor contributing to the coefficient, with the water-saving irrigation area being identified as the primary factor influencing the irrigation water effective utilization coefficient. Secondly, the stepwise regression model was selected considering the key factors, and the GM(1,1) model and Logistic growth model were selected considering the time series. Finally, it was constructed of a variable weight combination model with enhanced prediction accuracy, which utilized the three weight values derived from the error values of the stepwise regression method, GM (1,1) model and Logistic growth model. The prediction error revealed that the curve of the variable weight model aligns well with the measure results curve, demonstrating a prediction accuracy that was markedly superior to that of the individual models, making it suitable for predicting the irrigation water effective utilization coefficient.The variable weight combination model was utilized to predict and analyze the irrigation water effective utilization coefficient in Guangdong Province from 2023 to 2035. The prediction result indicated that the forecast value of the irrigation water effective utilization coefficient will reach 0.679 2 in Guangdong Province by 2035.The theoretical reference is provided for the planning and management system of agricultural water resources. It is of great significance to the upgrading and modernization of irrigation districts in China as well as to the reform of agricultural water prices.
LUO Yufu，LIN Kairong
,
，FANG Yuming，ZHANG Jingwen
,
，ZHANG Qingtao
,
，ZHUANG Luwen
,
，ZHU Han，CHEN Gang
2024, 22(4):728-735.
Abstract:
With the rapid pace of urbanization in the past few decades, both the height and density of buildings within cities experienced a noticeable surge. This transformation not only altered the skyline but also introduced new dynamics to natural processes, notably in the interplay between wind fields and rainfall runoff. This study delved into the intricate relationship between wind fields and their influence on runoff within built environments. Under the action of wind, raindrops tend to fall obliquely with an angle and form inclined rainfall. Inclined rainfall is intercepted by buildings with large heights. Meanwhile, part of the area behind the building is shielded due to the existence of the building. According to the phenomenon discussed above, this study endeavored to improve the existing methods of runoff calculation specific to building areas.The proposed formula includes five terms, which are ground runoff, building wall runoff, roof runoff, ground infiltration and evaporation during rainfall period. To improve the accuracy of the proposed formula, the dynamic characteristics of wind field and the characteristics of building areas were considered. The dynamic characteristics of wind field were reflected by adopting reduction factors. The characteristics of building areas were reflected by including the shielding effect between buildings. The shielding effect between buildings existed when the building distance is smaller than the length of shielded area. Rainfall runoff experiments were conducted to validate the soundness of the improved formula. Different scenarios with different inclined rainfall angle and building environments were designed. The experimental results closely mirrored the outcomes predicted by the formula, underscoring its effectiveness in capturing the flow characteristics unique to building areas. This correlation served as a testament to the formula's reliability. Buoyed by this success, the study embarked on an extended exploration of runoff patterns within urban construction zones.In the case of single-family dwellings and sparsely constructed areas, the angle at which rainfall descends exhibited a palpable influence on runoff generation. As the incline of precipitation increased, a discernible decrease in runoff within these areas was observed. This phenomenon was possibly the result of the increasing building shielding effects when the inclined rainfall angle increases. Conversely, complex mechanisms of runoff calculation were found in densely populated urban areas. Here, the building coverage ratio exerted a direct influence on water flow within the vicinity. As the number of buildings grew, accompanied by an escalation in building density, a twofold effect emerged. On one hand, this surge amplified the expanse of building wall runoff, as a greater surface area was exposed to the rainfall. Concurrently, the proliferation of buildings enhanced their collective shielding effect, thus instigating a nuanced trend in runoff dynamics. Initially, there was an upswing in runoff, as the augmented surface area contributed to a surge in water collection. However, this trend exhibited a tipping point, after which the runoff gradually receded.In summary, a formula for runoff calculation of building areas considering the impact of wind fields was proposed. Rainfall runoff experiments were conducted to testify its rationality. Based on the formula proposed, the runoff producing characteristics of different building areas were explored. In sparse distributed building area, the runoff producing is mainly influenced by the inclined rainfall angle; while in dense distributed building area, the runoff producing is not only influenced by the inclined rainfall angle but also the feature of building areas.
With the rapid pace of urbanization in the past few decades, both the height and density of buildings within cities experienced a noticeable surge. This transformation not only altered the skyline but also introduced new dynamics to natural processes, notably in the interplay between wind fields and rainfall runoff. This study delved into the intricate relationship between wind fields and their influence on runoff within built environments. Under the action of wind, raindrops tend to fall obliquely with an angle and form inclined rainfall. Inclined rainfall is intercepted by buildings with large heights. Meanwhile, part of the area behind the building is shielded due to the existence of the building. According to the phenomenon discussed above, this study endeavored to improve the existing methods of runoff calculation specific to building areas.The proposed formula includes five terms, which are ground runoff, building wall runoff, roof runoff, ground infiltration and evaporation during rainfall period. To improve the accuracy of the proposed formula, the dynamic characteristics of wind field and the characteristics of building areas were considered. The dynamic characteristics of wind field were reflected by adopting reduction factors. The characteristics of building areas were reflected by including the shielding effect between buildings. The shielding effect between buildings existed when the building distance is smaller than the length of shielded area. Rainfall runoff experiments were conducted to validate the soundness of the improved formula. Different scenarios with different inclined rainfall angle and building environments were designed. The experimental results closely mirrored the outcomes predicted by the formula, underscoring its effectiveness in capturing the flow characteristics unique to building areas. This correlation served as a testament to the formula's reliability. Buoyed by this success, the study embarked on an extended exploration of runoff patterns within urban construction zones.In the case of single-family dwellings and sparsely constructed areas, the angle at which rainfall descends exhibited a palpable influence on runoff generation. As the incline of precipitation increased, a discernible decrease in runoff within these areas was observed. This phenomenon was possibly the result of the increasing building shielding effects when the inclined rainfall angle increases. Conversely, complex mechanisms of runoff calculation were found in densely populated urban areas. Here, the building coverage ratio exerted a direct influence on water flow within the vicinity. As the number of buildings grew, accompanied by an escalation in building density, a twofold effect emerged. On one hand, this surge amplified the expanse of building wall runoff, as a greater surface area was exposed to the rainfall. Concurrently, the proliferation of buildings enhanced their collective shielding effect, thus instigating a nuanced trend in runoff dynamics. Initially, there was an upswing in runoff, as the augmented surface area contributed to a surge in water collection. However, this trend exhibited a tipping point, after which the runoff gradually receded.In summary, a formula for runoff calculation of building areas considering the impact of wind fields was proposed. Rainfall runoff experiments were conducted to testify its rationality. Based on the formula proposed, the runoff producing characteristics of different building areas were explored. In sparse distributed building area, the runoff producing is mainly influenced by the inclined rainfall angle; while in dense distributed building area, the runoff producing is not only influenced by the inclined rainfall angle but also the feature of building areas.
12 Mechanisms of soil moisture response to rainfall infiltration in dry-hot valley of southwest China
2024, 22(4):736-746.
Abstract:
The dry-hot valley regions in southwest China have suffered serious soil erosion. Therefore, improving our understanding of soil moisture response to rainfall under different vegetation types in these regions can provide valuable insights into rainfall infiltration and redistribution patterns on hillslopes, which is of vital importance for soil erosion management.This study investigated these processes in the dry-hot valley of the Reshuihe River catchment in Sichuan Province. Soil moisture was monitored continuously at 30-minute intervals at five depths (10, 20, 50, 75, and 100 cm) under woodland and grassland surfaces over 10 months. Rainfall events were classified based on the K-means clustering algorithm and 8 soil properties (rainfall infiltration depth, lag time of soil moisture response to rainfall, cumulative rainfall required for the response, relative maximum soil moisture increment, and relative maximum water storage increment) used to characterize the soil moisture response to rainfall.The results showed that rainfall infiltration is jointly controlled by rainfall properties, vegetation covers, and initial soil moisture conditions. The threshold value of rainfall amount for soil moisture response was 1.88 mm under woodland, while it increased to 9.15 mm under grassland. Soil moisture in woodland responded more readily and allowed greater infiltration depths with less influence from rainfall properties than that in grassland, which suggested that rainfall is more effectively absorbed and replenished deep soil moisture in woodland. Moreover, rainfall events with higher intensities promoted deeper percolation and more profound replenishment of soil moisture within the deeper layers of the soil. In conditions where the initial soil was wetter, soil moisture more swiftly responded to rainfall.These findings highlighted the complex interplay of vegetation covers, rainfall characteristics, and initial soil moisture conditions in the rainfall infiltration process, and deepened our understanding of soil moisture dynamics and rainfall infiltration mechanisms in the dry-hot valley. Firstly, these findings underscored the vital role of vegetation covers in mitigating soil erosion and managing water resources. The differences in rainfall thresholds for soil moisture response between woodland and grassland suggested that woodland can significantly enhance the ability to capture and retain rainfall in the landscape. These were particularly crucial in regions with a high risk of soil erosion, especially in the dry-hot valley. Additionally, the study emphasized the importance of rainfall properties, such as the rainfall intensity and the rainfall amount, as they significantly impacted on the depth and the recharge of soil moisture. Recognizing how rainfall properties affect soil moisture dynamics can inform more precise water management strategies and help optimize water resources utilization in dry-hot valleys. Furthermore, understanding the processes of soil moisture response to rainfall and their cotrolling factors can aid in developing more effective irrigation strategies and groundwater management practices, especially in areas with limited water resources. Such insights provided a solid scientific foundation for guiding soil and water conservation efforts in these regions.
The dry-hot valley regions in southwest China have suffered serious soil erosion. Therefore, improving our understanding of soil moisture response to rainfall under different vegetation types in these regions can provide valuable insights into rainfall infiltration and redistribution patterns on hillslopes, which is of vital importance for soil erosion management.This study investigated these processes in the dry-hot valley of the Reshuihe River catchment in Sichuan Province. Soil moisture was monitored continuously at 30-minute intervals at five depths (10, 20, 50, 75, and 100 cm) under woodland and grassland surfaces over 10 months. Rainfall events were classified based on the K-means clustering algorithm and 8 soil properties (rainfall infiltration depth, lag time of soil moisture response to rainfall, cumulative rainfall required for the response, relative maximum soil moisture increment, and relative maximum water storage increment) used to characterize the soil moisture response to rainfall.The results showed that rainfall infiltration is jointly controlled by rainfall properties, vegetation covers, and initial soil moisture conditions. The threshold value of rainfall amount for soil moisture response was 1.88 mm under woodland, while it increased to 9.15 mm under grassland. Soil moisture in woodland responded more readily and allowed greater infiltration depths with less influence from rainfall properties than that in grassland, which suggested that rainfall is more effectively absorbed and replenished deep soil moisture in woodland. Moreover, rainfall events with higher intensities promoted deeper percolation and more profound replenishment of soil moisture within the deeper layers of the soil. In conditions where the initial soil was wetter, soil moisture more swiftly responded to rainfall.These findings highlighted the complex interplay of vegetation covers, rainfall characteristics, and initial soil moisture conditions in the rainfall infiltration process, and deepened our understanding of soil moisture dynamics and rainfall infiltration mechanisms in the dry-hot valley. Firstly, these findings underscored the vital role of vegetation covers in mitigating soil erosion and managing water resources. The differences in rainfall thresholds for soil moisture response between woodland and grassland suggested that woodland can significantly enhance the ability to capture and retain rainfall in the landscape. These were particularly crucial in regions with a high risk of soil erosion, especially in the dry-hot valley. Additionally, the study emphasized the importance of rainfall properties, such as the rainfall intensity and the rainfall amount, as they significantly impacted on the depth and the recharge of soil moisture. Recognizing how rainfall properties affect soil moisture dynamics can inform more precise water management strategies and help optimize water resources utilization in dry-hot valleys. Furthermore, understanding the processes of soil moisture response to rainfall and their cotrolling factors can aid in developing more effective irrigation strategies and groundwater management practices, especially in areas with limited water resources. Such insights provided a solid scientific foundation for guiding soil and water conservation efforts in these regions.
2024, 22(4):747-758.
Abstract:
In recent years, many scholars have studied the coordinated evaluation of water resources linkage system, mainly focusing on water-economic society, water-energy-food, water-vegetation-soil, water-economy-ecology and other fields. The research scale mainly involves watershed scale and regional scale, and the evaluation method mainly adopts qualitative evaluation. Generally speaking, there are different combinations of grey correlation degree, pressure-state-response model, coupling coordination model, distance coordination degree and so on. It is well known that qualitative evaluation methods have certain ambiguity in the process of constructing evaluation index system and quantitative evaluation criteria. The uncertainty cloud theory proposed by LI Deyi in China can fully describe the uncertainty of qualitative and quantitative indicators and realize the mutual transformation of qualitative and quantitative processes. It was less applied in the evaluation of coupling coordination of water resources correlation systems. Therefore, cloud theory is introduced to construct cloud coupling coordination model to analyze and evaluate the coordination of water resources correlation systems, which makes the evaluation results more generalized.The index system of water resources correlation system including 21 indexes was established. The entropy weight-analytic hierarchy process combination method was used to determine the weight of the evaluation index. The cloud uncertainty theory was introduced to construct the cloud coupling coordination model. The cloud similarity was used to quantitatively give the evaluation results of coupling coordination degree of water resources correlation system. Compared with the traditional coupling coordination model, it had better adaptability and generalization. Taking Shandong Province as an example, the spatial and temporal variation characteristics of coordination between water resources correlation systems from 2010 to 2021 were analyzed.The comprehensive evaluation index of the economic and social subsystem was also growing, reaching a maximum of 0.634 in 2021; the comprehensive evaluation index of the ecological environment subsystem was only 0.237 at the beginning of 2010. The coupling coordination degree of water resources correlation system in Shandong Province has been continuously improved as a whole, from 0.608 in 2010 to 0.715 in 2021, realizing the transition from primary coordination to intermediate coordination. In space, the coupling coordination degree of each city in the province showed the distribution characteristics of high in the east and low in the west, and the coupling coordination degree had been continuously improved with time.The coupling and coordinated development ability of Jinan City and Qingdao City is the best, reaching a good coordination level. The coupling and coordinated development ability of Dezhou City and Binzhou City is relatively slow, maintaining at the primary coordination level. In the future, Shandong Province should strengthen the coordinated development of water resources correlation systems in the northwest plain of Shandong Province and promote the spatial balance of the whole province.
In recent years, many scholars have studied the coordinated evaluation of water resources linkage system, mainly focusing on water-economic society, water-energy-food, water-vegetation-soil, water-economy-ecology and other fields. The research scale mainly involves watershed scale and regional scale, and the evaluation method mainly adopts qualitative evaluation. Generally speaking, there are different combinations of grey correlation degree, pressure-state-response model, coupling coordination model, distance coordination degree and so on. It is well known that qualitative evaluation methods have certain ambiguity in the process of constructing evaluation index system and quantitative evaluation criteria. The uncertainty cloud theory proposed by LI Deyi in China can fully describe the uncertainty of qualitative and quantitative indicators and realize the mutual transformation of qualitative and quantitative processes. It was less applied in the evaluation of coupling coordination of water resources correlation systems. Therefore, cloud theory is introduced to construct cloud coupling coordination model to analyze and evaluate the coordination of water resources correlation systems, which makes the evaluation results more generalized.The index system of water resources correlation system including 21 indexes was established. The entropy weight-analytic hierarchy process combination method was used to determine the weight of the evaluation index. The cloud uncertainty theory was introduced to construct the cloud coupling coordination model. The cloud similarity was used to quantitatively give the evaluation results of coupling coordination degree of water resources correlation system. Compared with the traditional coupling coordination model, it had better adaptability and generalization. Taking Shandong Province as an example, the spatial and temporal variation characteristics of coordination between water resources correlation systems from 2010 to 2021 were analyzed.The comprehensive evaluation index of the economic and social subsystem was also growing, reaching a maximum of 0.634 in 2021; the comprehensive evaluation index of the ecological environment subsystem was only 0.237 at the beginning of 2010. The coupling coordination degree of water resources correlation system in Shandong Province has been continuously improved as a whole, from 0.608 in 2010 to 0.715 in 2021, realizing the transition from primary coordination to intermediate coordination. In space, the coupling coordination degree of each city in the province showed the distribution characteristics of high in the east and low in the west, and the coupling coordination degree had been continuously improved with time.The coupling and coordinated development ability of Jinan City and Qingdao City is the best, reaching a good coordination level. The coupling and coordinated development ability of Dezhou City and Binzhou City is relatively slow, maintaining at the primary coordination level. In the future, Shandong Province should strengthen the coordinated development of water resources correlation systems in the northwest plain of Shandong Province and promote the spatial balance of the whole province.
2024, 22(4):759-773.
Abstract:
Soil moisture is an important variable for vegetation growth, drought monitoring and agricultural water management, controlling water, energy and carbon exchange processes. Although traditionally observed soil moisture is highly accurate, it is difficult to obtain and spatially poorly representative; fortunately, with the development of satellites and reanalysis data, the difficulty of insufficient observed soil moisture data has been alleviated. As an indirect estimate of soil moisture, satellite and reanalysis data inevitably produce spatio-temporal systematic biases and random errors, especially in a region with complex climate and topography such as Yunnan Province, the applicability of these soil moisture products is still unclear, so it is necessary to assess the quality of these products.This study aimed to evaluate the applicability of five different soil moisture data in Yunnan Province and their performance under different wet and dry conditions, including ERA5-Land, GLDAS, SMAP, MERRA-2, and ESA CCI, were evaluated based on in-situ data and the triple-collocation (TC) in Yunnan Province. The results show that: (1) compared with the site data, the deviations of the five products were all positive (0.090-0.122), which significantly overestimated soil moisture in Yunnan Province, but the trends and magnitudes of the changes were consistent, and all of them were able to capture the temporal changes of soil moisture; (2) the assessment results based on the in-situ data showed that, on the yearly scale, ERA5-Land (0.456) and SMAP (0.454) matched the site data the highest, followed by ESA CCI (0.439); the assessment results of dry and wet seasons showed that all product correlations were lower than the annual scale, and the wet season was higher than the dry season, but the wet season showed a greater positive bias, with SMAP performing optimally in both the dry season (0.323) and the wet season (0.418); and (3) the results of the assessment based on the TC method showed that the correlations of ERA5-Land (0.925) and ESA CCI (0.931) had the highest correlation, followed by GLDAS (0.890) and MERRA-2 (0.864), the assessment results of the dry and wet seasons were consistent with the assessment of the site data, and the correlation of most of the products also showed a decreasing trend in comparison with the annual scale with a larger decrease in the dry season; and the R for SMAP dry and wet seasons were 0.828 and 0.770, respectively, which were the worst performers in both cases; The R (0.912) and ESD (0.020) of MERRA-2 in the wet season were better than its annual scale assessment. Taken together, ESA CCI has higher correlation and best accuracy, and is more suitable for monitoring surface soil moisture in Yunnan Province.The assessment results based on in-situ data and the TC method exhibited similarities but also differences. Both methods indicated that ERA5-Land and ESA CCI performed well across both assessments. Additionally, the performance of different products varied between the dry and wet seasons. However, there was a discrepancy in the performance of SMAP and MERRA-2 between the two assessment methods. In the site-based assessment, SMAP demonstrated high accuracy while MERRA-2 showed lower accuracy. Conversely, in the TC-based assessment, SMAP performed the poorest while MERRA-2 exhibited improved performance. Integrating both assessment methods enhanced our understanding of the accuracy and applicability of the different soil moisture products.
Soil moisture is an important variable for vegetation growth, drought monitoring and agricultural water management, controlling water, energy and carbon exchange processes. Although traditionally observed soil moisture is highly accurate, it is difficult to obtain and spatially poorly representative; fortunately, with the development of satellites and reanalysis data, the difficulty of insufficient observed soil moisture data has been alleviated. As an indirect estimate of soil moisture, satellite and reanalysis data inevitably produce spatio-temporal systematic biases and random errors, especially in a region with complex climate and topography such as Yunnan Province, the applicability of these soil moisture products is still unclear, so it is necessary to assess the quality of these products.This study aimed to evaluate the applicability of five different soil moisture data in Yunnan Province and their performance under different wet and dry conditions, including ERA5-Land, GLDAS, SMAP, MERRA-2, and ESA CCI, were evaluated based on in-situ data and the triple-collocation (TC) in Yunnan Province. The results show that: (1) compared with the site data, the deviations of the five products were all positive (0.090-0.122), which significantly overestimated soil moisture in Yunnan Province, but the trends and magnitudes of the changes were consistent, and all of them were able to capture the temporal changes of soil moisture; (2) the assessment results based on the in-situ data showed that, on the yearly scale, ERA5-Land (0.456) and SMAP (0.454) matched the site data the highest, followed by ESA CCI (0.439); the assessment results of dry and wet seasons showed that all product correlations were lower than the annual scale, and the wet season was higher than the dry season, but the wet season showed a greater positive bias, with SMAP performing optimally in both the dry season (0.323) and the wet season (0.418); and (3) the results of the assessment based on the TC method showed that the correlations of ERA5-Land (0.925) and ESA CCI (0.931) had the highest correlation, followed by GLDAS (0.890) and MERRA-2 (0.864), the assessment results of the dry and wet seasons were consistent with the assessment of the site data, and the correlation of most of the products also showed a decreasing trend in comparison with the annual scale with a larger decrease in the dry season; and the R for SMAP dry and wet seasons were 0.828 and 0.770, respectively, which were the worst performers in both cases; The R (0.912) and ESD (0.020) of MERRA-2 in the wet season were better than its annual scale assessment. Taken together, ESA CCI has higher correlation and best accuracy, and is more suitable for monitoring surface soil moisture in Yunnan Province.The assessment results based on in-situ data and the TC method exhibited similarities but also differences. Both methods indicated that ERA5-Land and ESA CCI performed well across both assessments. Additionally, the performance of different products varied between the dry and wet seasons. However, there was a discrepancy in the performance of SMAP and MERRA-2 between the two assessment methods. In the site-based assessment, SMAP demonstrated high accuracy while MERRA-2 showed lower accuracy. Conversely, in the TC-based assessment, SMAP performed the poorest while MERRA-2 exhibited improved performance. Integrating both assessment methods enhanced our understanding of the accuracy and applicability of the different soil moisture products.
2024, 22(4):774-787.
Abstract:
The Yellow River Delta, the most comprehensive and youngest coastal wetland in China, exhibited the dual characteristics of abundant resources and fragile ecological environment. The severe soil salinization and halophytes play a critical role in salinization control.Tamarix chinensis was a typical halophyte adjusting water salt balance. So, the aim of this paper was revealing the mechanisms of plants impact on soil water and salt in coastal wetlands and providing scientific reference for the protection and restoration of coastal wetlands. The study focused on soil water and salt around Tamarix chinensis Lour in the Yellow River Delta wetland. The sample collection location was selected on the buffer zone on the south side of the Yellow River Delta Nature Reserve, which were the Tamarix communities with minimal human interference. A relatively independent tamarisk shrub with vigorous growth was selected in the community. Four sets of soil profiles were successively taken from north, south, east and west, each set consists of 4 soil profiles which were able to represent the status of the soil distancing 50 cm, 100 cm, 150 cm, and 200 cm from the root of the shrub. Each soil profile was layered in layers of 0-5 cm, 5-10 cm, 10-20 cm, 20-40 cm and beneath 40 cm of the ground water level visible. the eight major ions (HCO3-、Cl?、CO32-、K+、Na+、Ca2+、Mg2+) and moisture content in the soil were monitored.To reveal the influenced mechanism of coastal wetland plants on soil water and salt, the spatiotemporal characteristics and coupling relationship of soil water and salt around the habitat of Tamarix shrub in the Yellow River Delta were analyzed. The results showed that: The soil moisture content under the plant crown was significantly higher than that of the edge of plant crown and the bare ground and showed a trend of gradual decreasing from main stem of the Tamarix to far away. The water aggregating rate showed a clear “water island” pattern, in the soil layer above 20 cm, the accumulation rate under the plant crown was significantly higher than that of the crown edge, while the opposite was in the soil layer below 20 cm. Soil salt ions were well correlated with total salt, among which Cl?, Na+ and Mg2+ were significantly correlated, and the changes in the contents of three ions under the crown of tamarisk were relatively small in all directions of east, south, west and north. Due to the salt absorption by the root system of Chinese tamarisk, the enrichment rate of total salinity under the plant crown was less than that at the crown edge and showed a clear “salt valley” pattern. The high coupling degree of soil water-salinity appeared in the states of high salt content and low moisture content around the Tamarix shrub. The high coupling situation occurred in the surface soil around the tamarisk, on the south and west two sides, and in the bare land far from the tamarisk. At different directions around the shrub, the coupling degree of soil water-salinity was manifested as west > south > north > east. The soil water and salinity content showed the significant negative correlation. Under the influence of the Chinese Tamarisk, the coupling degree of water and salt appeared a gradually decreasing trend from far to near the Tamarisk. As the increase of the soil depth, the influence of external factors gradually weakens, and the coupling degree decreased with the increase of soil depth.
The Yellow River Delta, the most comprehensive and youngest coastal wetland in China, exhibited the dual characteristics of abundant resources and fragile ecological environment. The severe soil salinization and halophytes play a critical role in salinization control.Tamarix chinensis was a typical halophyte adjusting water salt balance. So, the aim of this paper was revealing the mechanisms of plants impact on soil water and salt in coastal wetlands and providing scientific reference for the protection and restoration of coastal wetlands. The study focused on soil water and salt around Tamarix chinensis Lour in the Yellow River Delta wetland. The sample collection location was selected on the buffer zone on the south side of the Yellow River Delta Nature Reserve, which were the Tamarix communities with minimal human interference. A relatively independent tamarisk shrub with vigorous growth was selected in the community. Four sets of soil profiles were successively taken from north, south, east and west, each set consists of 4 soil profiles which were able to represent the status of the soil distancing 50 cm, 100 cm, 150 cm, and 200 cm from the root of the shrub. Each soil profile was layered in layers of 0-5 cm, 5-10 cm, 10-20 cm, 20-40 cm and beneath 40 cm of the ground water level visible. the eight major ions (HCO3-、Cl?、CO32-、K+、Na+、Ca2+、Mg2+) and moisture content in the soil were monitored.To reveal the influenced mechanism of coastal wetland plants on soil water and salt, the spatiotemporal characteristics and coupling relationship of soil water and salt around the habitat of Tamarix shrub in the Yellow River Delta were analyzed. The results showed that: The soil moisture content under the plant crown was significantly higher than that of the edge of plant crown and the bare ground and showed a trend of gradual decreasing from main stem of the Tamarix to far away. The water aggregating rate showed a clear “water island” pattern, in the soil layer above 20 cm, the accumulation rate under the plant crown was significantly higher than that of the crown edge, while the opposite was in the soil layer below 20 cm. Soil salt ions were well correlated with total salt, among which Cl?, Na+ and Mg2+ were significantly correlated, and the changes in the contents of three ions under the crown of tamarisk were relatively small in all directions of east, south, west and north. Due to the salt absorption by the root system of Chinese tamarisk, the enrichment rate of total salinity under the plant crown was less than that at the crown edge and showed a clear “salt valley” pattern. The high coupling degree of soil water-salinity appeared in the states of high salt content and low moisture content around the Tamarix shrub. The high coupling situation occurred in the surface soil around the tamarisk, on the south and west two sides, and in the bare land far from the tamarisk. At different directions around the shrub, the coupling degree of soil water-salinity was manifested as west > south > north > east. The soil water and salinity content showed the significant negative correlation. Under the influence of the Chinese Tamarisk, the coupling degree of water and salt appeared a gradually decreasing trend from far to near the Tamarisk. As the increase of the soil depth, the influence of external factors gradually weakens, and the coupling degree decreased with the increase of soil depth.
2024, 22(4):788-797.
Abstract:
The application of digital twin technology in the South-to-North Water Transfers Project is explored, with a specific emphasis on a pioneering digital twin project at a pumping station, aiming to promote the digitization trend in water resources engineering. Focused on the construction goal of the digital twin pumping station, which aims to achieve "unmanned and minimally manned" operations, the research highlights the critical transition from sensory analysis to intelligent analysis for the realization of key intelligent capabilities at the pumping station. While advanced methods such as unmanned aerial vehicle intelligent surveillance, smart image recognition technology, and intelligent inspection robots have been applied in the field of intelligent substations, limitations exist in the visualization of monitoring results.To fully consider the multifactorial impacts on the operational safety and reliability of the pumping station, the need for the intelligent inspection of the digital twin pumping station is emphasized, combining Building Information Modeling for precise modeling, Web Geographic Information System technology, and monitoring videos to provide more accurate visual feedback. The research adopts the integration of Building Information Modeling and Web Geographic Information System technologies to construct a three-dimensional scene. The three-dimensional video integration technology is used to ensures the accurate overlay of monitoring videos onto the geographical coordinates of the three-dimensional model. Through the Cesium engine, the coordinates of monitoring cameras are standardized to World Geodetic System 1984, achieving precise integration of virtual scenes with real-time monitoring. Simultaneously, with the linkage between Building Information Modeling models and monitoring, event listeners are defined to dynamically call monitoring platform interfaces, detecting changes in camera perspectives and ensuring synchronization with the scene. In terms of intelligent image recognition, real-time recognition of numerical values on equipment dials and indicator light statuses is achieved, combined with monitoring device data to judge equipment abnormalities.Significant practical results have been achieved through the research. The system is equipped with high-resolution monitoring devices, enabling automatic triggering of alarms upon detecting anomalies through real-time data collection and image processing. Furthermore, the digital twin pumping station's three-dimensional intelligent inspection system efficiently generates detailed inspection reports, encompassing inspection results, monitoring images, sensor data, and equipment status information. In application scenarios, the system automatically focuses on problematic areas, highlighting abnormal equipment and achieving digitalized intelligent inspections, thereby enhancing equipment and environmental safety and reducing potential risks.In summary, a comprehensive technical solution for the three-dimensional intelligent inspection system of the digital twin pumping station is provided. Despite facing some challenges, such as improving three-dimensional video integration effects and image recognition results, efficient operations for the digital twin pumping station have been achieved through the introduction of strategies like progressive Building Information Modeling model lightweighting. Future directions include further advancing three-dimensional video integration and intelligent image recognition technologies to enhance visualization and inspection quality, promoting collaborative operations among components, and realizing unmanned operations for the pumping station's intelligent management on a more robust foundation.
The application of digital twin technology in the South-to-North Water Transfers Project is explored, with a specific emphasis on a pioneering digital twin project at a pumping station, aiming to promote the digitization trend in water resources engineering. Focused on the construction goal of the digital twin pumping station, which aims to achieve "unmanned and minimally manned" operations, the research highlights the critical transition from sensory analysis to intelligent analysis for the realization of key intelligent capabilities at the pumping station. While advanced methods such as unmanned aerial vehicle intelligent surveillance, smart image recognition technology, and intelligent inspection robots have been applied in the field of intelligent substations, limitations exist in the visualization of monitoring results.To fully consider the multifactorial impacts on the operational safety and reliability of the pumping station, the need for the intelligent inspection of the digital twin pumping station is emphasized, combining Building Information Modeling for precise modeling, Web Geographic Information System technology, and monitoring videos to provide more accurate visual feedback. The research adopts the integration of Building Information Modeling and Web Geographic Information System technologies to construct a three-dimensional scene. The three-dimensional video integration technology is used to ensures the accurate overlay of monitoring videos onto the geographical coordinates of the three-dimensional model. Through the Cesium engine, the coordinates of monitoring cameras are standardized to World Geodetic System 1984, achieving precise integration of virtual scenes with real-time monitoring. Simultaneously, with the linkage between Building Information Modeling models and monitoring, event listeners are defined to dynamically call monitoring platform interfaces, detecting changes in camera perspectives and ensuring synchronization with the scene. In terms of intelligent image recognition, real-time recognition of numerical values on equipment dials and indicator light statuses is achieved, combined with monitoring device data to judge equipment abnormalities.Significant practical results have been achieved through the research. The system is equipped with high-resolution monitoring devices, enabling automatic triggering of alarms upon detecting anomalies through real-time data collection and image processing. Furthermore, the digital twin pumping station's three-dimensional intelligent inspection system efficiently generates detailed inspection reports, encompassing inspection results, monitoring images, sensor data, and equipment status information. In application scenarios, the system automatically focuses on problematic areas, highlighting abnormal equipment and achieving digitalized intelligent inspections, thereby enhancing equipment and environmental safety and reducing potential risks.In summary, a comprehensive technical solution for the three-dimensional intelligent inspection system of the digital twin pumping station is provided. Despite facing some challenges, such as improving three-dimensional video integration effects and image recognition results, efficient operations for the digital twin pumping station have been achieved through the introduction of strategies like progressive Building Information Modeling model lightweighting. Future directions include further advancing three-dimensional video integration and intelligent image recognition technologies to enhance visualization and inspection quality, promoting collaborative operations among components, and realizing unmanned operations for the pumping station's intelligent management on a more robust foundation.
2024, 22(4):798-809.
Abstract:
South-to-North Water Transfers Project is a large-scale water diversion project to alleviate the severe shortage of water resources in northern China. Practical experience show that algae can grow rapidly under specific conditions along the main canal. The mixture of algae residues moves with water flow and is prone to siltation in the static water area near the discharge gate and diversion outlet, as well as in the front pool of the pumping station. Therefore, algae sedimentation tank was proposed to build near the Middle Route of South-to-North Water Transfers Project to settle the algae and other mixtures in the main canal. Due to being short of universal standard for the design of sedimentation tanks, the required planar distance for settling algae and other mixtures need to be studied, so as to provide key design parameters for its engineering layout.The method of on-site experiments was used to study the sedimentation characteristics of algae and other mixtures in the main canal of the Middle Route Project. In this way, the effectiveness of the length of the sedimentation tank could be estimated. Then, the method of numerical simulation was adopted to analyze the water flow characteristics in the sedimentation tank under design condition. The existing plan may not be effective in settlement efficiency. Thus, some improved schemes were proposed characterized by setting diversion piers, and their effects were explored by numerical simulation.The results indicated that with the increase of the average flow velocity, the effective settlement distance increases while the effective settlement rate decreases, when the water depth is basically the same. For the initial design scheme, the mainstream leans towards the left side of the tank, and there is a large area of low flow velocity reflux on the right side of the tank, which accounts for about 57% of the total area. When longitudinal diversion piers were arranged evenly along the cross-section in the inlet diffusion zone, the percentage of water area of the recirculation zone in the sedimentation tank was decreased from 57% to 7%, the average flow velocity in the tank was decreased from about 0.10 m/s to about 0.07 m/s, and the average water age was decreased from about 18 h to about 6 h under the design condition. When transverse diversion piers were arranged similarly, the percentage of water area of the recirculation zone in the sedimentation tank was decreased from 57% to 14%, while the decrease of average flow velocity in the tank and the average water age was almost the same as the plan of longitudinal diversion piers.The conclusion indicates that the effective settling distance of algae and other mixtures is 1,064 m under the design working conditions of the sedimentation tank, which means that algae and other mixtures could settle within the sedimentation tank. However, the utilization efficiency of the initial layout plan of the sedimentation tank is relatively low. With the deployment of longitudinal diversion piers, the flow smoothness and the water exchange capacity in the sedimentation tank could be improved. Findings of this study could provide technical support for the overall layout design of the algae sedimentation tank. In the subsequent in-depth research, three-dimensional simulation and other means should be used to fully study the sedimentation characteristics of the tank to further improve the design.
South-to-North Water Transfers Project is a large-scale water diversion project to alleviate the severe shortage of water resources in northern China. Practical experience show that algae can grow rapidly under specific conditions along the main canal. The mixture of algae residues moves with water flow and is prone to siltation in the static water area near the discharge gate and diversion outlet, as well as in the front pool of the pumping station. Therefore, algae sedimentation tank was proposed to build near the Middle Route of South-to-North Water Transfers Project to settle the algae and other mixtures in the main canal. Due to being short of universal standard for the design of sedimentation tanks, the required planar distance for settling algae and other mixtures need to be studied, so as to provide key design parameters for its engineering layout.The method of on-site experiments was used to study the sedimentation characteristics of algae and other mixtures in the main canal of the Middle Route Project. In this way, the effectiveness of the length of the sedimentation tank could be estimated. Then, the method of numerical simulation was adopted to analyze the water flow characteristics in the sedimentation tank under design condition. The existing plan may not be effective in settlement efficiency. Thus, some improved schemes were proposed characterized by setting diversion piers, and their effects were explored by numerical simulation.The results indicated that with the increase of the average flow velocity, the effective settlement distance increases while the effective settlement rate decreases, when the water depth is basically the same. For the initial design scheme, the mainstream leans towards the left side of the tank, and there is a large area of low flow velocity reflux on the right side of the tank, which accounts for about 57% of the total area. When longitudinal diversion piers were arranged evenly along the cross-section in the inlet diffusion zone, the percentage of water area of the recirculation zone in the sedimentation tank was decreased from 57% to 7%, the average flow velocity in the tank was decreased from about 0.10 m/s to about 0.07 m/s, and the average water age was decreased from about 18 h to about 6 h under the design condition. When transverse diversion piers were arranged similarly, the percentage of water area of the recirculation zone in the sedimentation tank was decreased from 57% to 14%, while the decrease of average flow velocity in the tank and the average water age was almost the same as the plan of longitudinal diversion piers.The conclusion indicates that the effective settling distance of algae and other mixtures is 1,064 m under the design working conditions of the sedimentation tank, which means that algae and other mixtures could settle within the sedimentation tank. However, the utilization efficiency of the initial layout plan of the sedimentation tank is relatively low. With the deployment of longitudinal diversion piers, the flow smoothness and the water exchange capacity in the sedimentation tank could be improved. Findings of this study could provide technical support for the overall layout design of the algae sedimentation tank. In the subsequent in-depth research, three-dimensional simulation and other means should be used to fully study the sedimentation characteristics of the tank to further improve the design.
2024, 22(4):810-820.
Abstract:
A large north-south area with self-flowing water transportation was spanned by the Middle Route of the South-to-North Water Transfers Project. During the winter water transportation process, the water temperature is affected by weather, which can lead to ice conditions in the Hebei section of the channel. Therefore, scientific and quantitative evaluation of winter temperature in the areas along the Project is an important basis for analyzing the occurrence and evolution of ice conditions in the main canal.In this study, Handan, Zhengding, and Zhuozhou were used as representative regions, and the fitting of statistical frequency distribution and theoretical probability distribution was analyzed using daily winter temperature data from 1979 to 2021. Additionally, a new quantitative evaluation model for winter temperature was proposed based on the standardized temperature index method.The results showed that: (1) The standardized temperature index method's evaluation of cold and warm conditions in winter was generally consistent with the national standard method. However, fewer years for delineating strong cold winters and warm winters in each representative area was evaluated by the standardized temperature index method compared to the national standard method. (2) The temperature values corresponding to cold and warm level thresholds, calculated based on January temperature in each representative area, were significantly lower than those calculated based on the entire three months of winter. The temperature value decreased as the representative area moves farther north. (3) According to the evaluation of standardized temperature index method, the probabilities of strong cold winter occurrence in Handan, Zhengding, and Zhuozhou were 7.14%, 9.52%, and 4.76%, respectively. The probabilities of weak cold winter and above occurrence are 38.09%, 40.48%, and 38.09%, respectively. The probabilities of normal winter were 21.43%, 28.57% and 21.43%, the probabilities of weak warm winter and above occurrence were 40.48%, 30.95% and 40.48, respectively, and the probabilities of strong warm winter were 4.76%, 7.14% and 2.38%, respectively.Compared to the national standard method based on the normal distribution, the characterization of skewed probability distribution of temperature series was considered through these results, making it more scientifically sound in distinguishing relative temperature conditions and more valuable for promotion and application.
A large north-south area with self-flowing water transportation was spanned by the Middle Route of the South-to-North Water Transfers Project. During the winter water transportation process, the water temperature is affected by weather, which can lead to ice conditions in the Hebei section of the channel. Therefore, scientific and quantitative evaluation of winter temperature in the areas along the Project is an important basis for analyzing the occurrence and evolution of ice conditions in the main canal.In this study, Handan, Zhengding, and Zhuozhou were used as representative regions, and the fitting of statistical frequency distribution and theoretical probability distribution was analyzed using daily winter temperature data from 1979 to 2021. Additionally, a new quantitative evaluation model for winter temperature was proposed based on the standardized temperature index method.The results showed that: (1) The standardized temperature index method's evaluation of cold and warm conditions in winter was generally consistent with the national standard method. However, fewer years for delineating strong cold winters and warm winters in each representative area was evaluated by the standardized temperature index method compared to the national standard method. (2) The temperature values corresponding to cold and warm level thresholds, calculated based on January temperature in each representative area, were significantly lower than those calculated based on the entire three months of winter. The temperature value decreased as the representative area moves farther north. (3) According to the evaluation of standardized temperature index method, the probabilities of strong cold winter occurrence in Handan, Zhengding, and Zhuozhou were 7.14%, 9.52%, and 4.76%, respectively. The probabilities of weak cold winter and above occurrence are 38.09%, 40.48%, and 38.09%, respectively. The probabilities of normal winter were 21.43%, 28.57% and 21.43%, the probabilities of weak warm winter and above occurrence were 40.48%, 30.95% and 40.48, respectively, and the probabilities of strong warm winter were 4.76%, 7.14% and 2.38%, respectively.Compared to the national standard method based on the normal distribution, the characterization of skewed probability distribution of temperature series was considered through these results, making it more scientifically sound in distinguishing relative temperature conditions and more valuable for promotion and application.
2024, 22(4):821-832.
Abstract:
The fast pump-to-turbine transition process of a pumped storage unit is one of the most complex and dangerous operating conditions, which involves complex hydraulic, mechanical, and electrical processes. It can be highly responsive to the electrical power system regulation demands, thus being a critical process for pumped storage power station. The correct prediction of this hydraulic transient process is crucial for not incurring in issues during operation.A three-dimensional numerical model of the transition process of a pumped storage hydraulic system was proposed and analysed. Numerical simulations were carried out to investigate the hydraulic instability during this transition process, and the study was carried out from three perspectives: the variations of external parameters, the pressure fluctuations within the pump-turbine unit, and the evolution of flow patterns in the pump-turbine.Results indicated that: (1) During the fast pump-to-turbine transition process, the opening and closing of the guide vanes have an instantaneous impact on the hydrodynamic performance within the pump-turbine unit. The variations in discharge, torque, and axial force exhibit stepwise changes during the movement of the guide vanes. Periods of significant oscillation and drastic fluctuations in torque are prone to occur during the pump braking operating condition and the reversal of the runner speed. (2) The pressure fluctuations within the vaneless region and runner exhibit significant variations during the transition process. Notably, the pressure fluctuations in the vaneless region are particularly pronounced. The temporal variations in pressure at monitoring points in the spiral casing, stay vanes, and guide vanes regions exhibit similar trends with the magnitude of pressure variations increasing from the spiral casing to the guide vanes. The draft tube region does not generate tailrace eddy, thus avoiding intense pressure fluctuations. (3) During the transition process, the inertia of the water flow and the blocking effect of the guide vanes, contributes to the occurrence of high-speed circulation in the vaneless region, which is the reason for the intense pressure fluctuations observed in the vaneless region. The internal flow radically alters and gets more complex when the guide vanes are closed, the flow rate goes to zero, or the runner speed drops to zero. The rapid changes in the guide vane opening, flow direction, and rotational direction become the main causes of the pump-turbine's hydraulic instability.In conclusion, a numerical three-dimensional model was reported for the entire flow system of a pumped storage station. Simulations were carried out to investigate the transitional process of the fast pump-to-turbine. The research delved into the variations of external parameters, the pressure fluctuations within the pump-turbine unit, and the evolution of flow patterns during the fast pump-to-turbine transition process. The variations in discharge, torque, and axial force exhibited stepwise changes during the movement of the guide vanes during the fast pump-to-turbine transition process. The pressure fluctuations within the vaneless region and runner exhibited significant variations during the pump braking operating condition. The rapid changes in the guide vane opening, flow direction, and rotational direction becomed the main causes of the pump-turbine's hydraulic instability. To the authors’ opinion, this research considerably contributes to the understanding of the hydraulic transient mechanisms during the fast pump-to-turbine transition process, and provides theoretical guidance for enhancing stability and optimizing control strategies during the transitional process.
The fast pump-to-turbine transition process of a pumped storage unit is one of the most complex and dangerous operating conditions, which involves complex hydraulic, mechanical, and electrical processes. It can be highly responsive to the electrical power system regulation demands, thus being a critical process for pumped storage power station. The correct prediction of this hydraulic transient process is crucial for not incurring in issues during operation.A three-dimensional numerical model of the transition process of a pumped storage hydraulic system was proposed and analysed. Numerical simulations were carried out to investigate the hydraulic instability during this transition process, and the study was carried out from three perspectives: the variations of external parameters, the pressure fluctuations within the pump-turbine unit, and the evolution of flow patterns in the pump-turbine.Results indicated that: (1) During the fast pump-to-turbine transition process, the opening and closing of the guide vanes have an instantaneous impact on the hydrodynamic performance within the pump-turbine unit. The variations in discharge, torque, and axial force exhibit stepwise changes during the movement of the guide vanes. Periods of significant oscillation and drastic fluctuations in torque are prone to occur during the pump braking operating condition and the reversal of the runner speed. (2) The pressure fluctuations within the vaneless region and runner exhibit significant variations during the transition process. Notably, the pressure fluctuations in the vaneless region are particularly pronounced. The temporal variations in pressure at monitoring points in the spiral casing, stay vanes, and guide vanes regions exhibit similar trends with the magnitude of pressure variations increasing from the spiral casing to the guide vanes. The draft tube region does not generate tailrace eddy, thus avoiding intense pressure fluctuations. (3) During the transition process, the inertia of the water flow and the blocking effect of the guide vanes, contributes to the occurrence of high-speed circulation in the vaneless region, which is the reason for the intense pressure fluctuations observed in the vaneless region. The internal flow radically alters and gets more complex when the guide vanes are closed, the flow rate goes to zero, or the runner speed drops to zero. The rapid changes in the guide vane opening, flow direction, and rotational direction become the main causes of the pump-turbine's hydraulic instability.In conclusion, a numerical three-dimensional model was reported for the entire flow system of a pumped storage station. Simulations were carried out to investigate the transitional process of the fast pump-to-turbine. The research delved into the variations of external parameters, the pressure fluctuations within the pump-turbine unit, and the evolution of flow patterns during the fast pump-to-turbine transition process. The variations in discharge, torque, and axial force exhibited stepwise changes during the movement of the guide vanes during the fast pump-to-turbine transition process. The pressure fluctuations within the vaneless region and runner exhibited significant variations during the pump braking operating condition. The rapid changes in the guide vane opening, flow direction, and rotational direction becomed the main causes of the pump-turbine's hydraulic instability. To the authors’ opinion, this research considerably contributes to the understanding of the hydraulic transient mechanisms during the fast pump-to-turbine transition process, and provides theoretical guidance for enhancing stability and optimizing control strategies during the transitional process.
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