Volume ,2024 Issue 1
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- Water circulation response and water demand situation change under “DoubleCarbon” strategy
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- Ecological regulation of algae in Middle Route of South-to-North Water Diversion Project
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- Practice and countermeasures of the great protection of the Yangtze River
- Driving effect evolution and spatial differentiation of water use change in China
- Simulation of pipeline network drainage at urban community scales based on SWMM:A case study in Fuzhou City
- Interaction mechanism between urbanization and ecological security in nine provinces of the Yellow River basin
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Abstract:
In the 1990s, British scholar Allan introduced the concept of virtual water to quantify the water resources consumed in economic activities. Water-scarce countries procure water-intensive products through commerce to ensure supply and water security. With worldwide conferences and forums debating it extensively, virtual water research has acquired at traction. Database searches reveal a total of 29,471 domestic and international research papers on virtual water, showing a consistent growth trend. However, the applicability of virtual water strategy varies across water-scarce regions, leading to debates over its effectiveness. Rooted in the theory of comparative advantage, virtual water strategy overlooks multifaceted influences. Currently, the predominant body of research is centered around the calculation of scale and analysis of characteristics related to virtual water transfer. However, the driving causes of virtual water transfer remain conspicuously scarce.Incorporated the theory of comparative advantage, the scientific validity and effectiveness of virtual water research were heightened. The virtual water flow patterns of agriculture, forestry, animal husbandry, fishery, industry, construction, wholesale and retail, transportation, accommodation, and catering sectors across Chinese provinces in 2007, 2012 and 2017 were analyzed. Metrics such as the location quotient and growth quotient index were employed to establish the quantitative relationship between the pattern of virtual water flow and industrial comparative advantage.The results showed that the virtual water flow pattern in China was closely related to the industrial comparative advantage. The location quotient index can explain 72% of China’s virtual water transfer volume, while the growth quotient index substantiates 71% of China’s virtual water transfer change volume. The location and growth quotients of different industries are negatively correlated with the corresponding virtual water transfer volume and virtual water transfer change volume. This shows that virtual water associated with a specific industry predominantly relocates from regions boasting comparative advantages to those devoid of such advantages, and the speed of industry development may lead to a corresponding change in the magnitude of virtual water transfer.The prerequisites for implementing virtual water strategies are identified and the scientific value of virtual water research is discussed. The valuable insights into the driving causes of virtual water transfer are also provided and the development of virtual water strategies in China can be informed. By understanding the correlation between virtual water flow patterns and industrial comparative advantage, policymakers can make informed decisions to promote sustainable water resource management.
In the 1990s, British scholar Allan introduced the concept of virtual water to quantify the water resources consumed in economic activities. Water-scarce countries procure water-intensive products through commerce to ensure supply and water security. With worldwide conferences and forums debating it extensively, virtual water research has acquired at traction. Database searches reveal a total of 29,471 domestic and international research papers on virtual water, showing a consistent growth trend. However, the applicability of virtual water strategy varies across water-scarce regions, leading to debates over its effectiveness. Rooted in the theory of comparative advantage, virtual water strategy overlooks multifaceted influences. Currently, the predominant body of research is centered around the calculation of scale and analysis of characteristics related to virtual water transfer. However, the driving causes of virtual water transfer remain conspicuously scarce.Incorporated the theory of comparative advantage, the scientific validity and effectiveness of virtual water research were heightened. The virtual water flow patterns of agriculture, forestry, animal husbandry, fishery, industry, construction, wholesale and retail, transportation, accommodation, and catering sectors across Chinese provinces in 2007, 2012 and 2017 were analyzed. Metrics such as the location quotient and growth quotient index were employed to establish the quantitative relationship between the pattern of virtual water flow and industrial comparative advantage.The results showed that the virtual water flow pattern in China was closely related to the industrial comparative advantage. The location quotient index can explain 72% of China’s virtual water transfer volume, while the growth quotient index substantiates 71% of China’s virtual water transfer change volume. The location and growth quotients of different industries are negatively correlated with the corresponding virtual water transfer volume and virtual water transfer change volume. This shows that virtual water associated with a specific industry predominantly relocates from regions boasting comparative advantages to those devoid of such advantages, and the speed of industry development may lead to a corresponding change in the magnitude of virtual water transfer.The prerequisites for implementing virtual water strategies are identified and the scientific value of virtual water research is discussed. The valuable insights into the driving causes of virtual water transfer are also provided and the development of virtual water strategies in China can be informed. By understanding the correlation between virtual water flow patterns and industrial comparative advantage, policymakers can make informed decisions to promote sustainable water resource management.
Abstract:
Water, energy and food are the three material bases and strategic resources for the survival and development of human society. The United Nations predicts that global food and energy demand will increase by 60% and 80% respectively compared with 2016 by 2050; global water demand is expected to increase by 20% to 30%, with more than 2 billion people living in countries with severe water shortages. Beijing-Tianjin-Hebei region is one of the regions with the most significant "Water-Energy-Food" link and the most prominent joint risk in China, with a shortage of water resources and a large consumption of energy and food. With 0.7% of the country's water resources, it carries 8% of the country's population, 8.2% of the irrigated area and 10% of the total economy, which makes the security of the Water-Energy-Food system very tense. Therefore, the scientific and quantitative evaluation of the coordination degree of Water-Energy-Food coupling in Beijing-Tianjin-Hebei region and the analysis of the main obstacle factors of Water-Energy-Food coupling security are not only the key to improve the security of regional Water-Energy-Food system, but also an important link to adhere to sustainable development.Based on the collected data of the Beijing-Tianjin-Hebei region from 2000 to 2020, the key research and analysis of the Water-Energy-Food coupling security in the Beijing-Tianjin-Hebei region is carried out. The analytic hierarchy process was used to establish a comprehensive evaluation index system for Water-Energy-Food system security coupling, and the evaluation indicators were divided into water security systems, food security systems and energy security systems. The entropy weight method is used to determine the weight of each indicator; the comprehensive evaluation index of the Water-Energy-Food system in the Beijing-Tianjin-Hebei region and the characteristics of coupled security and coordinated development are analyzed through the coupling coordination degree model; and the obstacle degree model is used to analyze the influencing factors in the study area.The results show that the comprehensive evaluation index of water security, food security and energy security system in Beijing-Tianjin-Hebei region shows an overall upward trend from 2000 to 2020, and its floating range is 0.3?0.7. The floating range of Beijing comprehensive evaluation index is the largest (0.3?0.8), Tianjin comprehensive evaluation index is the smallest (0.4?0.7), and Hebei comprehensive evaluation index fluctuates between 0.3?0.7. The results of coupling coordination degree show that the coupling coordination degree of Water-Energy-Food in Beijing-Tianjin-Hebei region shows an upward trend from 2000 to 2020, and there are obvious differences between regions. Among them, the coupling coordination degree of Beijing is the highest, while that of Hebei Province is poor. The result of the obstacle degree of Beijing, Tianjin and Hebei as a whole and each region can be roughly divided into three stages: the fluctuation stage from 2000 to 2005, the transition stage from 2006 to 2015, and the stable stage from 2016 to 2020. Per capita water resources, COD discharge in wastewater, per capita energy consumption and total power per mu of agricultural machinery are the main obstacle factors.Based on the above analysis, Beijing's water security system, Tianjin's energy system, and Hebei's energy security system and food security system are the keys to the overall coupling and coordination of the Beijing-Tianjin-Hebei region. In the future, Beijing should improve water use efficiency, adjust water use structure, and tap water-saving potential; Tianjin and Hebei Province should focus on improving energy recycling efficiency, optimizing energy consumption structure, and carrying out low-carbon technology innovation to increase the pace of decarbonization; Hebei Province also needs to save energy, irrigation measures of water-saving, protect crops, reduce the affected area, and improve the efficiency of agricultural machinery.
Water, energy and food are the three material bases and strategic resources for the survival and development of human society. The United Nations predicts that global food and energy demand will increase by 60% and 80% respectively compared with 2016 by 2050; global water demand is expected to increase by 20% to 30%, with more than 2 billion people living in countries with severe water shortages. Beijing-Tianjin-Hebei region is one of the regions with the most significant "Water-Energy-Food" link and the most prominent joint risk in China, with a shortage of water resources and a large consumption of energy and food. With 0.7% of the country's water resources, it carries 8% of the country's population, 8.2% of the irrigated area and 10% of the total economy, which makes the security of the Water-Energy-Food system very tense. Therefore, the scientific and quantitative evaluation of the coordination degree of Water-Energy-Food coupling in Beijing-Tianjin-Hebei region and the analysis of the main obstacle factors of Water-Energy-Food coupling security are not only the key to improve the security of regional Water-Energy-Food system, but also an important link to adhere to sustainable development.Based on the collected data of the Beijing-Tianjin-Hebei region from 2000 to 2020, the key research and analysis of the Water-Energy-Food coupling security in the Beijing-Tianjin-Hebei region is carried out. The analytic hierarchy process was used to establish a comprehensive evaluation index system for Water-Energy-Food system security coupling, and the evaluation indicators were divided into water security systems, food security systems and energy security systems. The entropy weight method is used to determine the weight of each indicator; the comprehensive evaluation index of the Water-Energy-Food system in the Beijing-Tianjin-Hebei region and the characteristics of coupled security and coordinated development are analyzed through the coupling coordination degree model; and the obstacle degree model is used to analyze the influencing factors in the study area.The results show that the comprehensive evaluation index of water security, food security and energy security system in Beijing-Tianjin-Hebei region shows an overall upward trend from 2000 to 2020, and its floating range is 0.3?0.7. The floating range of Beijing comprehensive evaluation index is the largest (0.3?0.8), Tianjin comprehensive evaluation index is the smallest (0.4?0.7), and Hebei comprehensive evaluation index fluctuates between 0.3?0.7. The results of coupling coordination degree show that the coupling coordination degree of Water-Energy-Food in Beijing-Tianjin-Hebei region shows an upward trend from 2000 to 2020, and there are obvious differences between regions. Among them, the coupling coordination degree of Beijing is the highest, while that of Hebei Province is poor. The result of the obstacle degree of Beijing, Tianjin and Hebei as a whole and each region can be roughly divided into three stages: the fluctuation stage from 2000 to 2005, the transition stage from 2006 to 2015, and the stable stage from 2016 to 2020. Per capita water resources, COD discharge in wastewater, per capita energy consumption and total power per mu of agricultural machinery are the main obstacle factors.Based on the above analysis, Beijing's water security system, Tianjin's energy system, and Hebei's energy security system and food security system are the keys to the overall coupling and coordination of the Beijing-Tianjin-Hebei region. In the future, Beijing should improve water use efficiency, adjust water use structure, and tap water-saving potential; Tianjin and Hebei Province should focus on improving energy recycling efficiency, optimizing energy consumption structure, and carrying out low-carbon technology innovation to increase the pace of decarbonization; Hebei Province also needs to save energy, irrigation measures of water-saving, protect crops, reduce the affected area, and improve the efficiency of agricultural machinery.
ZHAO?Wenjie
1, 2，JU?Qin
1, 2，CAI?Huiyi
3，TANG?Zhiyang
1, 2，SHI?Qishu
1, 2，WANG?Rouxi
1, 2，LI?Sirui
1, 2
Abstract:
Runoff is an important part of the hydrological cycle and can respond to environmental changes. The Weihe River is the first-class tributary of the Yellow River basin and is also the most important water resource supply area, agricultural irrigation, and industrial water use in Guanzhong. Due to natural reasons such as large topographic relief, loose and porous soil, uneven distribution of precipitation within the year, and the intensification of human activities, the basin is characterized by frequent alternating water and drought disasters, serious soil erosion, and is a resource-type water-scarce area. In recent years, with climate change and the intensification of human activities, the ecological environment of the Weihe River basin has become more fragile, and the hydrological situation has also changed to different degrees. Therefore, analyzing the change characteristics of runoff in the Weihe River basin on multiple time scales and its influencing factors can help to understand the change rules of the hydrological situation of the basin and water resources planning and management.Based on the measured runoff data from 1961 to 2015 at Xianyang Hydrological Station in the Weihe River basin, a linear regression method was used to analyze the trend of runoff on different time scales. Several meteorological factors such as temperature, specific humidity, precipitation, solar radiation, wind speed, and Normalized Difference Vegetation Index (NDVI) were selected. The factors were screened by the smoothness test and Granger causality test. Vector Autoregression models are constructed to quantify the contribution of each influential factor to the runoff changes, and the differences of the main controlling factors of the runoff changes throughout the year, flood season, and non-flood season are explored.The runoff showed a decreasing trend, with decreasing rates of 0.76, 0.44, and 0.31 mm/（10a）respectively during the whole year, flood season and non-flood season from 1961 to 2015 in the Weihe River basin. Flood season runoff accounted for 65.5% of the total runoff, which was highly similar to the trend of the whole-year runoff. On the time scale, the runoff decreased significantly in the 1970s and 1990s. There were differences in the degree of runoff dispersion in different eras, with greater intra-annual dispersion of runoff in the 1970s and 1980s, and a more concentrated distribution of runoff from 2000 to 2009. The variance decomposition based on the vector autoregression model is used to analyze the effects of different lag times of meteorological elements and NDVI on runoff. On the annual scale, the influences of runoff changes were dominated by precipitation and supplemented by solar radiation and NDVI when the influences of the elements and runoff reached a steady state over time, with a contribution of 49.04% for precipitation and 18.45% and 13.60% for solar radiation and NDVI respectively. The contribution rate of precipitation to runoff is 49.04%, and the contribution rates of solar radiation and NDVI are 18.45% and 13.60% respectively, and the influence of each factor on runoff has different degrees of lag. The distribution of contributing factors to the runoff changes in the flood season and the annual scale were similar. During the flood season, precipitation was the main controlling factor for runoff changes, and the contribution of each factor was in the following order: precipitation＞specific humidity＞solar radiation＞NDVI＞ temperature. During the non-flood season, the main controlling factors were NDVI and solar radiation, with a contribution of more than 30%. The contribution of precipitation decreases significantly, the influence of NDVI on runoff increases significantly, the contribution of temperature increases to some extent, and the lag effect of the influencing factors becomes more obvious.During the flood season and the non-flood season, the main controlling factors affecting the runoff changes are different in the Weihe River basin. During the flood season, runoff changes are mainly influenced by precipitation, while the influence of precipitation is significantly reduced during the non-flood season, and the main controlling factors affecting runoff become NDVI and solar radiation.
Runoff is an important part of the hydrological cycle and can respond to environmental changes. The Weihe River is the first-class tributary of the Yellow River basin and is also the most important water resource supply area, agricultural irrigation, and industrial water use in Guanzhong. Due to natural reasons such as large topographic relief, loose and porous soil, uneven distribution of precipitation within the year, and the intensification of human activities, the basin is characterized by frequent alternating water and drought disasters, serious soil erosion, and is a resource-type water-scarce area. In recent years, with climate change and the intensification of human activities, the ecological environment of the Weihe River basin has become more fragile, and the hydrological situation has also changed to different degrees. Therefore, analyzing the change characteristics of runoff in the Weihe River basin on multiple time scales and its influencing factors can help to understand the change rules of the hydrological situation of the basin and water resources planning and management.Based on the measured runoff data from 1961 to 2015 at Xianyang Hydrological Station in the Weihe River basin, a linear regression method was used to analyze the trend of runoff on different time scales. Several meteorological factors such as temperature, specific humidity, precipitation, solar radiation, wind speed, and Normalized Difference Vegetation Index (NDVI) were selected. The factors were screened by the smoothness test and Granger causality test. Vector Autoregression models are constructed to quantify the contribution of each influential factor to the runoff changes, and the differences of the main controlling factors of the runoff changes throughout the year, flood season, and non-flood season are explored.The runoff showed a decreasing trend, with decreasing rates of 0.76, 0.44, and 0.31 mm/（10a）respectively during the whole year, flood season and non-flood season from 1961 to 2015 in the Weihe River basin. Flood season runoff accounted for 65.5% of the total runoff, which was highly similar to the trend of the whole-year runoff. On the time scale, the runoff decreased significantly in the 1970s and 1990s. There were differences in the degree of runoff dispersion in different eras, with greater intra-annual dispersion of runoff in the 1970s and 1980s, and a more concentrated distribution of runoff from 2000 to 2009. The variance decomposition based on the vector autoregression model is used to analyze the effects of different lag times of meteorological elements and NDVI on runoff. On the annual scale, the influences of runoff changes were dominated by precipitation and supplemented by solar radiation and NDVI when the influences of the elements and runoff reached a steady state over time, with a contribution of 49.04% for precipitation and 18.45% and 13.60% for solar radiation and NDVI respectively. The contribution rate of precipitation to runoff is 49.04%, and the contribution rates of solar radiation and NDVI are 18.45% and 13.60% respectively, and the influence of each factor on runoff has different degrees of lag. The distribution of contributing factors to the runoff changes in the flood season and the annual scale were similar. During the flood season, precipitation was the main controlling factor for runoff changes, and the contribution of each factor was in the following order: precipitation＞specific humidity＞solar radiation＞NDVI＞ temperature. During the non-flood season, the main controlling factors were NDVI and solar radiation, with a contribution of more than 30%. The contribution of precipitation decreases significantly, the influence of NDVI on runoff increases significantly, the contribution of temperature increases to some extent, and the lag effect of the influencing factors becomes more obvious.During the flood season and the non-flood season, the main controlling factors affecting the runoff changes are different in the Weihe River basin. During the flood season, runoff changes are mainly influenced by precipitation, while the influence of precipitation is significantly reduced during the non-flood season, and the main controlling factors affecting runoff become NDVI and solar radiation.
Abstract:
With the development of distributed hydrological models towards larger watersheds and finer granularity, computational efficiency gradually became a bottleneck, and parallel computing technology emerged as an effective solution to this challenge. In the realm of parallel computing for distributed hydrological models, most of the existing studies have primarily focused on CPU-based parallel techniques, with relatively limited research on GPU-based parallel methods. Furthermore, investigations on distributed hydrological models incorporating physical mechanisms remain scarce.This study centered around the physically-based distributed hydrological model WEP-L（water and energy transfer processes in large river basins）and explored the utilization of GPU-based parallel computing techniques. From a spatial perspective, the WEP-L model divides the watershed into numerous sub-basin units, where each unit's runoff calculations are independent, offering spatial parallelism. The interdependencies between simulation units were taken into account while allocating jobs to several computer units for parallel execution. Consequently, the runoff process of the model was parallelized based on sub-basins, dividing the Poyang Lake basin into 8,712 sub-units, and employing GPU threads to execute parallel computations through kernel functions.It is founded that the distributed hydrological model's suggested GPU-based parallel approach significantly accelerated the process. With an increase in GPU thread count, the parallel computing time steadily reduced. The parallel performance was most efficient when the total thread count closely approached the number of divided sub-basins. In the experimental Poyang Lake basin with 8,712 sub-basin units in the WEP-L model, the maximum speedup reached around 2.5. Secondly, the performance of GPU parallel computing was influenced not only by the degree of parallelism but also by the computational workload. With an increase in computational workload, both serial and parallel computation times increased. However, due to the smaller rate of increase in parallel computation time compared to the serial method, the speedup gradually increased, albeit at a diminishing rate. When the number of sub-basin units in the experimental WEP-L model increased to 24,897, the speedup ratio reached 3.5, indicating the considerable potential for GPU parallel algorithms in the computation of physically-based large-scale watershed distributed hydrological models.In conclusion, GPU-based parallel algorithms showed great promise for computing large-scale, physically-based, watershed-distributed hydrological models. The results indicated that the enhancement of parallel efficiency was contingent not only on the number of parallel threads activated but also on the size of the computational workload. The parallel calculation time decreased gradually as the number of GPU threads rose. As the computing demand rose, the speedup ratio increased correspondingly. GPU-based parallel computing represents the current trend in parallel computing. This study could provide valuable experience for other researchers exploring GPU parallel algorithms, contributing to the facilitation of interdisciplinary collaboration between computer science and water resources engineering.
With the development of distributed hydrological models towards larger watersheds and finer granularity, computational efficiency gradually became a bottleneck, and parallel computing technology emerged as an effective solution to this challenge. In the realm of parallel computing for distributed hydrological models, most of the existing studies have primarily focused on CPU-based parallel techniques, with relatively limited research on GPU-based parallel methods. Furthermore, investigations on distributed hydrological models incorporating physical mechanisms remain scarce.This study centered around the physically-based distributed hydrological model WEP-L（water and energy transfer processes in large river basins）and explored the utilization of GPU-based parallel computing techniques. From a spatial perspective, the WEP-L model divides the watershed into numerous sub-basin units, where each unit's runoff calculations are independent, offering spatial parallelism. The interdependencies between simulation units were taken into account while allocating jobs to several computer units for parallel execution. Consequently, the runoff process of the model was parallelized based on sub-basins, dividing the Poyang Lake basin into 8,712 sub-units, and employing GPU threads to execute parallel computations through kernel functions.It is founded that the distributed hydrological model's suggested GPU-based parallel approach significantly accelerated the process. With an increase in GPU thread count, the parallel computing time steadily reduced. The parallel performance was most efficient when the total thread count closely approached the number of divided sub-basins. In the experimental Poyang Lake basin with 8,712 sub-basin units in the WEP-L model, the maximum speedup reached around 2.5. Secondly, the performance of GPU parallel computing was influenced not only by the degree of parallelism but also by the computational workload. With an increase in computational workload, both serial and parallel computation times increased. However, due to the smaller rate of increase in parallel computation time compared to the serial method, the speedup gradually increased, albeit at a diminishing rate. When the number of sub-basin units in the experimental WEP-L model increased to 24,897, the speedup ratio reached 3.5, indicating the considerable potential for GPU parallel algorithms in the computation of physically-based large-scale watershed distributed hydrological models.In conclusion, GPU-based parallel algorithms showed great promise for computing large-scale, physically-based, watershed-distributed hydrological models. The results indicated that the enhancement of parallel efficiency was contingent not only on the number of parallel threads activated but also on the size of the computational workload. The parallel calculation time decreased gradually as the number of GPU threads rose. As the computing demand rose, the speedup ratio increased correspondingly. GPU-based parallel computing represents the current trend in parallel computing. This study could provide valuable experience for other researchers exploring GPU parallel algorithms, contributing to the facilitation of interdisciplinary collaboration between computer science and water resources engineering.
Abstract:
The multi-objective water optimal dispatching problem is the current research hotspot in the field of water resources. The Henan section of the Yangtze-to-Huaihe River Water Diversion Project involves a variety of water conveyance structures such as river channels, pipelines, gate pumps, and storage reservoirs, making the water supply scheduling system complex. Water scheduling for water diversion projects often needs to consider multiple scheduling objectives such as water supply assurance, energy consumption, and fairness. These objectives generally have competing relationships, making the problem relatively difficult to solve. Therefore, research on multi-objective optimization scheduling of water quantity for complex water diversion projects is particularly important.Current research adopts intelligent optimization algorithms to solve complex water scheduling models. These algorithms optimize the values of decision variables to achieve the optimal objective function under given constraints. In the process of water optimal dispatching models, handling constraints has always been a challenging problem for intelligent algorithms. Conventional intelligent algorithms perform random searches in the decision variable space within given upper and lower bounds. However, for complex scheduling systems, with numerous types of constraints and decision variables, and strong correlations among them, the feasible space is relatively small compared to the entire search space. This requires algorithms to increase iteration numbers to expand the search, resulting in longer computation time, poor convergence, and even the inability to find feasible solutions. To address this problem, a feasible search approach-based multi-objective optimization method is proposed to solve the multi-objective water optimization scheduling problem for the Henan section of the Yangtze-to-Huaihe River Water Diversion Project. The minimizing water shortage rate, total pumping volume of pump stations, and standard deviation of water shortage rate in the water destination regions are selected as objective functions, aiming to construct a multi-objective water volume optimization scheduling model from the perspectives of water supply security, energy consumption, and fairness. Based on the feasible search approach, combined with the process of reverse calculation and forward calculation, the constraints were addressed by involving the decision coefficients and maintaining the search space within the feasible domain through mapping relationships. The multi-objective non-dominated sorting genetic algorithm (NSGA-II) was utilized for the model solution, generating the Pareto optimal solution set. The entropy weight method was employed for scheme selection. A comparison was made between the scheme with the minimum water shortage rate and the scheme with the highest evaluation score based on the entropy-based weight method. Although the average water shortage rate of the optimal scheme based on the entropy-based weight method was relatively higher than that of the scheme with the minimum water shortage rate, the total pumping volume and the standard deviation of the water shortage rate were reduced. The total pumping volume decreased by approximately 2 million m3, and the standard deviation decreased by approximately 50.2%, respectively. Considering multiple objectives comprehensively, the optimal scheme with a higher balance of water shortage spatial distribution and lower energy consumption based on the entropy weight method was chosen as the optimal scheduling scheme. The results show that the NSGA-II algorithm based on the feasible search can effectively solve the multi-objective optimization problem of complex scheduling systems. The optimal schemes considering multiple objectives are more reasonable than single-objective schemes, providing decision support for the operation and management of the Henan section.
The multi-objective water optimal dispatching problem is the current research hotspot in the field of water resources. The Henan section of the Yangtze-to-Huaihe River Water Diversion Project involves a variety of water conveyance structures such as river channels, pipelines, gate pumps, and storage reservoirs, making the water supply scheduling system complex. Water scheduling for water diversion projects often needs to consider multiple scheduling objectives such as water supply assurance, energy consumption, and fairness. These objectives generally have competing relationships, making the problem relatively difficult to solve. Therefore, research on multi-objective optimization scheduling of water quantity for complex water diversion projects is particularly important.Current research adopts intelligent optimization algorithms to solve complex water scheduling models. These algorithms optimize the values of decision variables to achieve the optimal objective function under given constraints. In the process of water optimal dispatching models, handling constraints has always been a challenging problem for intelligent algorithms. Conventional intelligent algorithms perform random searches in the decision variable space within given upper and lower bounds. However, for complex scheduling systems, with numerous types of constraints and decision variables, and strong correlations among them, the feasible space is relatively small compared to the entire search space. This requires algorithms to increase iteration numbers to expand the search, resulting in longer computation time, poor convergence, and even the inability to find feasible solutions. To address this problem, a feasible search approach-based multi-objective optimization method is proposed to solve the multi-objective water optimization scheduling problem for the Henan section of the Yangtze-to-Huaihe River Water Diversion Project. The minimizing water shortage rate, total pumping volume of pump stations, and standard deviation of water shortage rate in the water destination regions are selected as objective functions, aiming to construct a multi-objective water volume optimization scheduling model from the perspectives of water supply security, energy consumption, and fairness. Based on the feasible search approach, combined with the process of reverse calculation and forward calculation, the constraints were addressed by involving the decision coefficients and maintaining the search space within the feasible domain through mapping relationships. The multi-objective non-dominated sorting genetic algorithm (NSGA-II) was utilized for the model solution, generating the Pareto optimal solution set. The entropy weight method was employed for scheme selection. A comparison was made between the scheme with the minimum water shortage rate and the scheme with the highest evaluation score based on the entropy-based weight method. Although the average water shortage rate of the optimal scheme based on the entropy-based weight method was relatively higher than that of the scheme with the minimum water shortage rate, the total pumping volume and the standard deviation of the water shortage rate were reduced. The total pumping volume decreased by approximately 2 million m3, and the standard deviation decreased by approximately 50.2%, respectively. Considering multiple objectives comprehensively, the optimal scheme with a higher balance of water shortage spatial distribution and lower energy consumption based on the entropy weight method was chosen as the optimal scheduling scheme. The results show that the NSGA-II algorithm based on the feasible search can effectively solve the multi-objective optimization problem of complex scheduling systems. The optimal schemes considering multiple objectives are more reasonable than single-objective schemes, providing decision support for the operation and management of the Henan section.
Abstract:
Compared to the traditional conceptual hydrological models, two-dimensional hydrodynamic models can provide more comprehensive hydraulic information of watershed surfaces, but the issue of long computational time restricts its widespread application. Exploring ways to improve the computational efficiency of two-dimensional hydraulic models has become one of the hot points and key technological challenges in current digital twin watershed development. The rapid advancement of GPU hardware technology has enabled the utilization of two-dimensional hydraulic models for the purpose of simulating watershed flood processes in real time. The potential applications of this technology in the construction of digital twin watersheds appear bright.The model is established based on a structured grid and adopts the Godunov scheme based on the finite volume method to discretize the complete two-dimensional shallow water equations. A high-performance accelerated calculation based on multiple GPUs is realized by combining MPI and CUDA computing architecture to meet the requirements of large-scale parallel computing tasks and realize the simultaneous work of multiple GPUs. MPI implements message passing between parallel processes based on the distributed storage model. Each process has a unique process rank at runtime and controls a GPU device. When using multiple GPUs for computation, the computational domain needs to be divided into multiple subdomains, and each GPU is assigned to compute a specific subdomain. Each subdomain is surrounded by an additional layer of grid cells that is used to communicate with adjacent subdomains. This outer layer of grid cells receives data from the adjacent subdomains to perform updates. Once the communication is completed, the computation continues within each subdomain.The model's numerical accuracy has been verified using ideal and real watershed cases, with a relative error of 0.011% for the peak discharge in the ideal case and 2.98% for the peak discharge in the real watershed case. The acceleration effect of the model under different cell resolutions was analyzed in the Baogaisi watershed. The results showed that when the total number of grids reaches a certain scale, the multi-GPU acceleration technology can obtain a satisfactory acceleration effect. When the grid resolutions of the watershed are 5 m, 2 m, and 1 m, the corresponding grid units are 861,605, 5384,807, and 21,539,061. The speedup ratios obtained by 8 Tesla V100 GPUs are 1.58, 3.92, and 5.77, respectively. Higher cell resolutions lead to more significant acceleration effects with multiple GPUs. The hydrodynamic model based on multi-GPU has great potential for acceleration and can provide strong technical support for the construction of digital twin river basins.
Compared to the traditional conceptual hydrological models, two-dimensional hydrodynamic models can provide more comprehensive hydraulic information of watershed surfaces, but the issue of long computational time restricts its widespread application. Exploring ways to improve the computational efficiency of two-dimensional hydraulic models has become one of the hot points and key technological challenges in current digital twin watershed development. The rapid advancement of GPU hardware technology has enabled the utilization of two-dimensional hydraulic models for the purpose of simulating watershed flood processes in real time. The potential applications of this technology in the construction of digital twin watersheds appear bright.The model is established based on a structured grid and adopts the Godunov scheme based on the finite volume method to discretize the complete two-dimensional shallow water equations. A high-performance accelerated calculation based on multiple GPUs is realized by combining MPI and CUDA computing architecture to meet the requirements of large-scale parallel computing tasks and realize the simultaneous work of multiple GPUs. MPI implements message passing between parallel processes based on the distributed storage model. Each process has a unique process rank at runtime and controls a GPU device. When using multiple GPUs for computation, the computational domain needs to be divided into multiple subdomains, and each GPU is assigned to compute a specific subdomain. Each subdomain is surrounded by an additional layer of grid cells that is used to communicate with adjacent subdomains. This outer layer of grid cells receives data from the adjacent subdomains to perform updates. Once the communication is completed, the computation continues within each subdomain.The model's numerical accuracy has been verified using ideal and real watershed cases, with a relative error of 0.011% for the peak discharge in the ideal case and 2.98% for the peak discharge in the real watershed case. The acceleration effect of the model under different cell resolutions was analyzed in the Baogaisi watershed. The results showed that when the total number of grids reaches a certain scale, the multi-GPU acceleration technology can obtain a satisfactory acceleration effect. When the grid resolutions of the watershed are 5 m, 2 m, and 1 m, the corresponding grid units are 861,605, 5384,807, and 21,539,061. The speedup ratios obtained by 8 Tesla V100 GPUs are 1.58, 3.92, and 5.77, respectively. Higher cell resolutions lead to more significant acceleration effects with multiple GPUs. The hydrodynamic model based on multi-GPU has great potential for acceleration and can provide strong technical support for the construction of digital twin river basins.
Calibration and verification of monthly precipitation forecasts from GFDL-SPEAR global climate model
Abstract:
Global climate models, formulating complex processes in the atmosphere, oceans, land, and sea ice, serve as effective tools to provide meteorological forecasts at the global scale for water resources management. Precipitation is one of the most important variables in hydrological processes. The predictive performances of streamflow, soil moisture, and other hydrological variables can be improved by utilizing precipitation forecasts from global climate models to drive hydrological models. In recent years, operational climate centers have developed different global climate models and produced global precipitation forecasts. Since 2020, the Geophysical Fluid Dynamics Laboratory (GFDL) has been operating the Seamless System for Prediction and EArth System Research (SPEAR) to generate monthly climate forecasts with lead times of up to twelve months. Monthly precipitation forecasts can be used to facilitate hydrological forecasting for wet season (May to October) and dry season (November to April of the subsequent year) in China. Three steps were taken to evaluate the predictive performances of GFDL-SPEAR monthly precipitation forecasts in China. Firstly, the time-series forecasts are extracted from global datasets for second-level water resources regionalization in China. The start times are set to be the beginning of May and November from 1991 to 2020 so that the obtained forecasts with twelve lead times can span the subsequent wet and dry seasons. Secondly, the Bernoulli-Gamma-Gaussian model is formulated to calibrate raw forecasts. Comparative experiments are devised to investigate the effectiveness of calibration on monthly amounts and accumulated totals. Thirdly, the Pearson correlation coefficient (EPCC), relative bias (ERB), alpha index (Eα) and continuous ranked probability skill score (ECRPSS) are computed to verify the association, bias, reliability, and skill of raw and calibrated forecasts in terms of monthly and accumulated precipitation. The results show that the predictive performance of the GFDL-SPEAR model tends to vary by season and region. Raw forecasts can be reasonably correlated with observations at a short lead time while the correlation tends to decrease with lead time. In particular, a reasonable correlation can be observed in the Yellow River, Yangtze River, and Southeast Rivers regions even at the one-year lead time. Raw forecasts usually suffer from substantial biases and random errors. Specifically, the values of ERB range from –20% to 50% and the values of Eα fall between 0.4 to 0.8, primarily owing to positive biases and too-narrow ensemble spreads in raw forecasts. In the meantime, forecast errors can accumulate with lead time and then deteriorate predictive performances of accumulated precipitation. The Bernoulli-Gamma-Gaussian model is effective in removing systematic biases and generating reliable time-series forecasts. For calibrated forecasts, it is shown that the values of ERB tend to be nearly zero and that the values of Eα are mostly larger than 0.8 across all lead times. While raw forecasts can be negatively skillful due to impacts of systematic and random errors, the values of ECRPSS for calibrated forecasts are overall improved by 25% and 45% for monthly and accumulated precipitation, respectively. Compared with the calibration on accumulated totals, the calibration on monthly amounts can further improve forecast skill, leading to higher ECRPSS for accumulated precipitation.The applicability of the GFDL-SPEAR monthly precipitation forecasts over second-level water resources regionalization in China was evaluated. The GFDL-SPEAR provides informative forecasts but suffers from systematic and random errors. The Bernoulli-Gamma-Gaussian model can effectively correct bias and generate reliable calibrated forecasts. The calibration on monthly amounts tends to outperform the calibration on accumulated totals by effectively leveraging forecasts across different lead times. Overall, the GFDL-SPEAR monthly precipitation forecasts calibrated by the Bernoulli-Gamma-Gaussian model can be used to inform hydrological forecasting and water resource management at a one-year lead time in China.
Global climate models, formulating complex processes in the atmosphere, oceans, land, and sea ice, serve as effective tools to provide meteorological forecasts at the global scale for water resources management. Precipitation is one of the most important variables in hydrological processes. The predictive performances of streamflow, soil moisture, and other hydrological variables can be improved by utilizing precipitation forecasts from global climate models to drive hydrological models. In recent years, operational climate centers have developed different global climate models and produced global precipitation forecasts. Since 2020, the Geophysical Fluid Dynamics Laboratory (GFDL) has been operating the Seamless System for Prediction and EArth System Research (SPEAR) to generate monthly climate forecasts with lead times of up to twelve months. Monthly precipitation forecasts can be used to facilitate hydrological forecasting for wet season (May to October) and dry season (November to April of the subsequent year) in China. Three steps were taken to evaluate the predictive performances of GFDL-SPEAR monthly precipitation forecasts in China. Firstly, the time-series forecasts are extracted from global datasets for second-level water resources regionalization in China. The start times are set to be the beginning of May and November from 1991 to 2020 so that the obtained forecasts with twelve lead times can span the subsequent wet and dry seasons. Secondly, the Bernoulli-Gamma-Gaussian model is formulated to calibrate raw forecasts. Comparative experiments are devised to investigate the effectiveness of calibration on monthly amounts and accumulated totals. Thirdly, the Pearson correlation coefficient (EPCC), relative bias (ERB), alpha index (Eα) and continuous ranked probability skill score (ECRPSS) are computed to verify the association, bias, reliability, and skill of raw and calibrated forecasts in terms of monthly and accumulated precipitation. The results show that the predictive performance of the GFDL-SPEAR model tends to vary by season and region. Raw forecasts can be reasonably correlated with observations at a short lead time while the correlation tends to decrease with lead time. In particular, a reasonable correlation can be observed in the Yellow River, Yangtze River, and Southeast Rivers regions even at the one-year lead time. Raw forecasts usually suffer from substantial biases and random errors. Specifically, the values of ERB range from –20% to 50% and the values of Eα fall between 0.4 to 0.8, primarily owing to positive biases and too-narrow ensemble spreads in raw forecasts. In the meantime, forecast errors can accumulate with lead time and then deteriorate predictive performances of accumulated precipitation. The Bernoulli-Gamma-Gaussian model is effective in removing systematic biases and generating reliable time-series forecasts. For calibrated forecasts, it is shown that the values of ERB tend to be nearly zero and that the values of Eα are mostly larger than 0.8 across all lead times. While raw forecasts can be negatively skillful due to impacts of systematic and random errors, the values of ECRPSS for calibrated forecasts are overall improved by 25% and 45% for monthly and accumulated precipitation, respectively. Compared with the calibration on accumulated totals, the calibration on monthly amounts can further improve forecast skill, leading to higher ECRPSS for accumulated precipitation.The applicability of the GFDL-SPEAR monthly precipitation forecasts over second-level water resources regionalization in China was evaluated. The GFDL-SPEAR provides informative forecasts but suffers from systematic and random errors. The Bernoulli-Gamma-Gaussian model can effectively correct bias and generate reliable calibrated forecasts. The calibration on monthly amounts tends to outperform the calibration on accumulated totals by effectively leveraging forecasts across different lead times. Overall, the GFDL-SPEAR monthly precipitation forecasts calibrated by the Bernoulli-Gamma-Gaussian model can be used to inform hydrological forecasting and water resource management at a one-year lead time in China.
ZHENG?Fang
1, 2，LI?Fangran
1, 2，GAN?Yiqun
3，SHAO?Dongyue
1, 2，
ZHANG?Yin
1, 2，CAO?Meichen
1, 2，DUAN?Tianyu
4
Abstract:
The Dongting Lake basin is the region of the middle reaches of the Yangtze River that provides ecosystem regulation functions. The hydrological connectivity of the Dongting Lake basin experienced profound and complex changes as a result of climate change and human activities. China emphasizes that ecohydrological environmental protection should be put in the first place, and assessing the impact of the occurrence of extreme climatic events on the regional hydrological environment would be of great significance in protecting the stability of the regional ecohydrological environment. Previous study quantitatively characterizes and predicts the changes in the hydrological connectivity of Dongting Lake in the last decades. It is beneficial for us to fully understand the water resources evolution of Dongting Lake, to ensure the security of water resources which has a significant theoretical and practical meaning in the Dongting Lake basin.The hydrological connectivity index was applied to characterize the changes in the hydrological connectivity and to study the contribution of extreme climatic events. This study was carried out using the hydrological connectivity index method, ETCCDI extreme climate index, Hurst index, and mathematical and statistical analysis methods. The results showed that the hydrological connectivity index presented the characteristics of summer > autumn > spring > winter. From the remote sensing images extracted from the water body, it could be seen that the Dongting Lake hydrological network was characterized by inhomogeneity. It is found that the hydrological connectivity of Dongting Lake would continue to change excessively in the future according to the persistence prediction. Dongting Lake IIC and PC had an obvious response to extreme precipitation events, while Dongting Lake IIC and PC did not significantly respond to extreme climate events.These results indicated that the hydrological connectivity of Dongting Lake was relatively stable in the last three decades. Without the interference of human activities, the hydrological connectivity of Dongting Lake would continue the decreasing trend in the future. The hydrological connectivity index gradually increased with the increase of water level and the growth rate gradually slowed down, and the increase of water level had a positive influence on it with a decreasing marginal effect. Extreme precipitation events had a more obvious positive effect on the hydrological connectivity, while extreme temperature events had a smaller effect on the hydrological connectivity. This could be because heavy rainfall events may affect lake and river levels through direct water inputs, whereas extreme high or low temperatures may only indirectly affect lake and river levels through the evapotranspiration of water.
The Dongting Lake basin is the region of the middle reaches of the Yangtze River that provides ecosystem regulation functions. The hydrological connectivity of the Dongting Lake basin experienced profound and complex changes as a result of climate change and human activities. China emphasizes that ecohydrological environmental protection should be put in the first place, and assessing the impact of the occurrence of extreme climatic events on the regional hydrological environment would be of great significance in protecting the stability of the regional ecohydrological environment. Previous study quantitatively characterizes and predicts the changes in the hydrological connectivity of Dongting Lake in the last decades. It is beneficial for us to fully understand the water resources evolution of Dongting Lake, to ensure the security of water resources which has a significant theoretical and practical meaning in the Dongting Lake basin.The hydrological connectivity index was applied to characterize the changes in the hydrological connectivity and to study the contribution of extreme climatic events. This study was carried out using the hydrological connectivity index method, ETCCDI extreme climate index, Hurst index, and mathematical and statistical analysis methods. The results showed that the hydrological connectivity index presented the characteristics of summer > autumn > spring > winter. From the remote sensing images extracted from the water body, it could be seen that the Dongting Lake hydrological network was characterized by inhomogeneity. It is found that the hydrological connectivity of Dongting Lake would continue to change excessively in the future according to the persistence prediction. Dongting Lake IIC and PC had an obvious response to extreme precipitation events, while Dongting Lake IIC and PC did not significantly respond to extreme climate events.These results indicated that the hydrological connectivity of Dongting Lake was relatively stable in the last three decades. Without the interference of human activities, the hydrological connectivity of Dongting Lake would continue the decreasing trend in the future. The hydrological connectivity index gradually increased with the increase of water level and the growth rate gradually slowed down, and the increase of water level had a positive influence on it with a decreasing marginal effect. Extreme precipitation events had a more obvious positive effect on the hydrological connectivity, while extreme temperature events had a smaller effect on the hydrological connectivity. This could be because heavy rainfall events may affect lake and river levels through direct water inputs, whereas extreme high or low temperatures may only indirectly affect lake and river levels through the evapotranspiration of water.
Abstract:
Extreme rainstorms in many cities have broken historical records repeatedly, thus urban flooding disasters occur frequently. Under the background of global warming, extreme rainstorm events showed an increasing trend. In the past few decades, China's urbanization process advanced rapidly, and the rain island effect caused by rapid urbanization also led to the frequent occurrence of extreme rainstorm events to some extent. The characteristics of many urban rainstorms changed significantly, and the consistency of rainfall series no longer existed, so the current rainfall intensity formula may no longer be applicable. The rainfall intensity formula is one of the basic bases for the construction of urban drainage and waterlogging prevention infrastructure. To objectively reflect the characteristics and rules of urban rainfall and avoid underestimating the intensity of design rainstorms, the current formula needed to be reviewed and updated.The main urban area of Hangzhou was taken as an example, based on the rainfall extreme data from 1982 to 2022 at Zhakou station, the Mann-Kendall trend analysis method and the Pettitt test method were selected to analyze the trend and abrupt change of the annual rainfall extreme and selected Pearson type III distribution and Gumbel distribution curve for model fitting, respectively. The particle swarm optimization algorithm was used for parameter estimation of the rainfall intensity formula, and the newly derived rainfall intensity formulas were reviewed and analyzed. The rationality of the newly derived rainfall intensity formulas was indirectly analyzed using the rainfall extreme data of Gongchenqiao, Zhongcun, and Qibao rainfall stations and the extended historical rainfall extreme data of Zhakou station.The following results were obtained: (a) At the significance level of 0.05, the maximum rainfall series of 10, 20, 30, 45, 90, 360, 540 and 720 min at Zhakou station showed an insignificant downward trend. The annual maximum rainfall series of 60, 120, 180, 240 and 1 440 min showed an insignificant upward trend, and there were no significant abrupt change points in different duration rainfall series. (b) The average absolute mean square deviations of the new rainfall intensity formulas obtained from Pearson type III distribution and Gumbel distribution were less than 0.05 mm/min, and their average relative mean square deviations were less than 5%. (c) The rainfall intensities of the two new formulas were significantly larger than that of the current formula for considering different durations except for the 10-minute duration. (d) Based on the rainfall extreme data of Gongchenqiao, Zhongcun, and Qibao rainfall stations, the design rainfall intensities of the current formula were indirectly verified to be small. (e) It was shown that the difference between the new formulas and the current formula was due to the change in sampling stations and the change in the data years. Trend analysis results of the rainfall series showed that extreme rainfall in the main city of Hangzhou showed an insignificant increase, so the new formulas were more reasonable and safer than the current formula.The rainfall intensity formulas of Pearson type III distribution and Gumbel distribution were deduced and compared with the current formula based on the rainfall extreme data from 1982 to 2022 at Zhakou station. The new rainfall intensity formulas derived from the latest rainstorm data could be used as a reference for the design of drainage and flood prevention projects and the construction of related facilities in the main urban area of Hangzhou.
Extreme rainstorms in many cities have broken historical records repeatedly, thus urban flooding disasters occur frequently. Under the background of global warming, extreme rainstorm events showed an increasing trend. In the past few decades, China's urbanization process advanced rapidly, and the rain island effect caused by rapid urbanization also led to the frequent occurrence of extreme rainstorm events to some extent. The characteristics of many urban rainstorms changed significantly, and the consistency of rainfall series no longer existed, so the current rainfall intensity formula may no longer be applicable. The rainfall intensity formula is one of the basic bases for the construction of urban drainage and waterlogging prevention infrastructure. To objectively reflect the characteristics and rules of urban rainfall and avoid underestimating the intensity of design rainstorms, the current formula needed to be reviewed and updated.The main urban area of Hangzhou was taken as an example, based on the rainfall extreme data from 1982 to 2022 at Zhakou station, the Mann-Kendall trend analysis method and the Pettitt test method were selected to analyze the trend and abrupt change of the annual rainfall extreme and selected Pearson type III distribution and Gumbel distribution curve for model fitting, respectively. The particle swarm optimization algorithm was used for parameter estimation of the rainfall intensity formula, and the newly derived rainfall intensity formulas were reviewed and analyzed. The rationality of the newly derived rainfall intensity formulas was indirectly analyzed using the rainfall extreme data of Gongchenqiao, Zhongcun, and Qibao rainfall stations and the extended historical rainfall extreme data of Zhakou station.The following results were obtained: (a) At the significance level of 0.05, the maximum rainfall series of 10, 20, 30, 45, 90, 360, 540 and 720 min at Zhakou station showed an insignificant downward trend. The annual maximum rainfall series of 60, 120, 180, 240 and 1 440 min showed an insignificant upward trend, and there were no significant abrupt change points in different duration rainfall series. (b) The average absolute mean square deviations of the new rainfall intensity formulas obtained from Pearson type III distribution and Gumbel distribution were less than 0.05 mm/min, and their average relative mean square deviations were less than 5%. (c) The rainfall intensities of the two new formulas were significantly larger than that of the current formula for considering different durations except for the 10-minute duration. (d) Based on the rainfall extreme data of Gongchenqiao, Zhongcun, and Qibao rainfall stations, the design rainfall intensities of the current formula were indirectly verified to be small. (e) It was shown that the difference between the new formulas and the current formula was due to the change in sampling stations and the change in the data years. Trend analysis results of the rainfall series showed that extreme rainfall in the main city of Hangzhou showed an insignificant increase, so the new formulas were more reasonable and safer than the current formula.The rainfall intensity formulas of Pearson type III distribution and Gumbel distribution were deduced and compared with the current formula based on the rainfall extreme data from 1982 to 2022 at Zhakou station. The new rainfall intensity formulas derived from the latest rainstorm data could be used as a reference for the design of drainage and flood prevention projects and the construction of related facilities in the main urban area of Hangzhou.
WANG?Yuanjiang
1, 2，JIANG?Shanhu
1, 2，LING?Zihan
2，CHEN?Hongxin
3，ZHANG?Xiaoxiang
2，REN?Liliang
1, 2
Abstract:
Mountain flood disasters generally refer to floods, landslides, and debris flows hazards caused by rainfall and snowmelt. They are characterized by their suddenness and devastating impact. Critical rainfall is a commonly used indicator for mountain flood disaster early warning, indicating that when the rainfall reaches a certain threshold within a certain period, the flow at the outlet of the watershed will exceed the warning flow, resulting in disastrous flooding. These disasters have caused severe social problems. It poses a significant threat to people's lives and property. So optimizing mountain flood early warning and addressing the shortcomings in flood control and disaster reduction are crucial steps in social development. Critical rainfall, as the most commonly used indicator for mountain flood early warning, has been studied by numerous scholars both domestically and internationally. However, there is limited research on the comprehensive consideration of the influence of random rainfall patterns and spatial distribution under different antecedent rainfall conditions on the critical rainfall for mountain flood early warning.To address these issues, the Pengfang small watershed is focused on as the research area and random rainfall patterns are generated, based on control conditions such as probability distribution functions. Based on the historical rainfall data from the Pengfang small watershed, the optimal distribution functions for the five sets of random rainfall patterns were as follows: Normal, Normal, Exponential, Normal, Exponential and Gamma distributions. The control conditions for these distribution functions were (0.50, 0.32), (0.50, 0.42), (0.50, 0.52), (0.17, 0.32), and (0.83, 0.32) respectively. The influence of different sets of random rainfall patterns is explored, considering different antecedent rainfall conditions, on the 6-hour critical rainfall for mountain flood early warning. Furthermore, the impact of rainfall spatial distribution on the 6-hour critical rainfall is also analyzed.The results are as follows: (1) Under rainfall patterns with a later peak position and larger peak values, critical rainfall exhibits significant fluctuations, leading to diverse disaster scenarios with higher uncertainty. (2) The influence of rainfall patterns on critical rainfall is smaller compared to the influence of antecedent rainfall. When the soil is relatively dry in the antecedent period and the coefficient of the peak position of the rainfall pattern is small, the critical rainfall value is relatively large. The change in the peak position has a smaller effect on the critical rainfall when the soil is moist in the antecedent period. While the peak value ratio of the rainfall pattern is larger, the critical rainfall value is relatively small, indicating a higher likelihood of causing mountain flood disasters. (3) In terms of rainfall spatial distribution, the rainfall is concentrated downstream, and the critical rainfall value is the smallest, indicating a higher likelihood of reaching the warning flow. However, the impact of rainfall spatial distribution on the critical rainfall is less significant compared to the impact of antecedent precipitation. Furthermore, as antecedent precipitation increases, the impact of rainfall spatial distribution on the critical rainfall gradually diminishes.The findings have significant implications for improving the accuracy of mountain flood disaster early warning and enhancing the early warning system. These research results can provide a scientific basis for the optimization and improvement of the mountain flood early warning system, aiming to better protect people's lives and properties and effectively respond to the challenges posed by mountain flood disasters.
Mountain flood disasters generally refer to floods, landslides, and debris flows hazards caused by rainfall and snowmelt. They are characterized by their suddenness and devastating impact. Critical rainfall is a commonly used indicator for mountain flood disaster early warning, indicating that when the rainfall reaches a certain threshold within a certain period, the flow at the outlet of the watershed will exceed the warning flow, resulting in disastrous flooding. These disasters have caused severe social problems. It poses a significant threat to people's lives and property. So optimizing mountain flood early warning and addressing the shortcomings in flood control and disaster reduction are crucial steps in social development. Critical rainfall, as the most commonly used indicator for mountain flood early warning, has been studied by numerous scholars both domestically and internationally. However, there is limited research on the comprehensive consideration of the influence of random rainfall patterns and spatial distribution under different antecedent rainfall conditions on the critical rainfall for mountain flood early warning.To address these issues, the Pengfang small watershed is focused on as the research area and random rainfall patterns are generated, based on control conditions such as probability distribution functions. Based on the historical rainfall data from the Pengfang small watershed, the optimal distribution functions for the five sets of random rainfall patterns were as follows: Normal, Normal, Exponential, Normal, Exponential and Gamma distributions. The control conditions for these distribution functions were (0.50, 0.32), (0.50, 0.42), (0.50, 0.52), (0.17, 0.32), and (0.83, 0.32) respectively. The influence of different sets of random rainfall patterns is explored, considering different antecedent rainfall conditions, on the 6-hour critical rainfall for mountain flood early warning. Furthermore, the impact of rainfall spatial distribution on the 6-hour critical rainfall is also analyzed.The results are as follows: (1) Under rainfall patterns with a later peak position and larger peak values, critical rainfall exhibits significant fluctuations, leading to diverse disaster scenarios with higher uncertainty. (2) The influence of rainfall patterns on critical rainfall is smaller compared to the influence of antecedent rainfall. When the soil is relatively dry in the antecedent period and the coefficient of the peak position of the rainfall pattern is small, the critical rainfall value is relatively large. The change in the peak position has a smaller effect on the critical rainfall when the soil is moist in the antecedent period. While the peak value ratio of the rainfall pattern is larger, the critical rainfall value is relatively small, indicating a higher likelihood of causing mountain flood disasters. (3) In terms of rainfall spatial distribution, the rainfall is concentrated downstream, and the critical rainfall value is the smallest, indicating a higher likelihood of reaching the warning flow. However, the impact of rainfall spatial distribution on the critical rainfall is less significant compared to the impact of antecedent precipitation. Furthermore, as antecedent precipitation increases, the impact of rainfall spatial distribution on the critical rainfall gradually diminishes.The findings have significant implications for improving the accuracy of mountain flood disaster early warning and enhancing the early warning system. These research results can provide a scientific basis for the optimization and improvement of the mountain flood early warning system, aiming to better protect people's lives and properties and effectively respond to the challenges posed by mountain flood disasters.
Abstract:
Prediction of hydrological time series is a challenging issue due to complicated hydrologic processes, which would greatly impact the water resources management and hydraulic engineering design. Related studies indicated that combined models, which are based on the decomposition-prediction-reconstruction mode usually perform much better for the prediction of hydrological time series than single models. A great number of studies have been conducted on diverse combinations and applications of combined models, however, a comprehensive evaluation of the applicability and stability of different combined models is lacking, leaving a research gap for this important issue. Four commonly used decomposition methods were applied, namely empirical mode decomposition (EMD), ensemble empirical mode decomposition (EEMD), modified ensemble empirical mode decomposition (MEEMD), and variational mode decomposition (VMD). The four decomposition methods were further combined with five representative prediction models, namely multivariable linear regression (MLR), random forest (RF), back propagation (BP), convolutional neural networks (CNN), and long short-term memory (LSTM), to establish a total of 20 combined models. These 20 combined models were used to predict the annual precipitation and flood season precipitation and conducted a comparative analysis of the models in the Miyun basin and Guanting basin in North China.in North China.Results showed that: (1) The single models predicted both annual precipitation and flood season precipitation more accurately in the Miyun basin than in the Guanting basin, but the single model’s performances were overall poor in the two basins. (2) The prediction results from the combined models after coupling with decomposition algorithms become much better than those from the single models, and the positive errors could be offset by the negative errors during the prediction processes when using the combined models, which could improve the overall prediction accuracy of precipitation. (3) Compared with the EMD and other algorithms, the VMD algorithm has the most significant effect on improving the prediction accuracy of precipitation, and the applicability and stability of the combined models is VMD-MLR> VMD-LSTM> VMD-BP> VMD-CNN.Moreover, the results indicated a single model can not accurately grasp the complex characteristics of the precipitation time series. The prediction accuracy of a single model could be approved through parameters optimization, however, the effect is not obvious. Compared with a single model, the combined models based on decomposition algorithms can effectively improve the prediction results. In the combined models, the effectiveness of decomposition algorithms (such as EMD and VMD) in decomposing the original time series directly affects the models' prediction results. After combining with the decomposition algorithm, the models' performance improves significantly, and their applicability and stability are greatly enhanced. After combining with the decomposition algorithm, even some simple models (such as MLR) can be used to accurately predict precipitation time series with complex variability patterns. Different model combinations and predictors lead to differences in prediction results among combined models. Therefore, more influencing factors (such as climate indicators) and more complex combined models based on the decomposition-prediction-reconstruction mode should be explored in future research to optimize the prediction model and prediction process, to further improve the prediction accuracy and reliability of the precipitation in this study area.
Prediction of hydrological time series is a challenging issue due to complicated hydrologic processes, which would greatly impact the water resources management and hydraulic engineering design. Related studies indicated that combined models, which are based on the decomposition-prediction-reconstruction mode usually perform much better for the prediction of hydrological time series than single models. A great number of studies have been conducted on diverse combinations and applications of combined models, however, a comprehensive evaluation of the applicability and stability of different combined models is lacking, leaving a research gap for this important issue. Four commonly used decomposition methods were applied, namely empirical mode decomposition (EMD), ensemble empirical mode decomposition (EEMD), modified ensemble empirical mode decomposition (MEEMD), and variational mode decomposition (VMD). The four decomposition methods were further combined with five representative prediction models, namely multivariable linear regression (MLR), random forest (RF), back propagation (BP), convolutional neural networks (CNN), and long short-term memory (LSTM), to establish a total of 20 combined models. These 20 combined models were used to predict the annual precipitation and flood season precipitation and conducted a comparative analysis of the models in the Miyun basin and Guanting basin in North China.in North China.Results showed that: (1) The single models predicted both annual precipitation and flood season precipitation more accurately in the Miyun basin than in the Guanting basin, but the single model’s performances were overall poor in the two basins. (2) The prediction results from the combined models after coupling with decomposition algorithms become much better than those from the single models, and the positive errors could be offset by the negative errors during the prediction processes when using the combined models, which could improve the overall prediction accuracy of precipitation. (3) Compared with the EMD and other algorithms, the VMD algorithm has the most significant effect on improving the prediction accuracy of precipitation, and the applicability and stability of the combined models is VMD-MLR> VMD-LSTM> VMD-BP> VMD-CNN.Moreover, the results indicated a single model can not accurately grasp the complex characteristics of the precipitation time series. The prediction accuracy of a single model could be approved through parameters optimization, however, the effect is not obvious. Compared with a single model, the combined models based on decomposition algorithms can effectively improve the prediction results. In the combined models, the effectiveness of decomposition algorithms (such as EMD and VMD) in decomposing the original time series directly affects the models' prediction results. After combining with the decomposition algorithm, the models' performance improves significantly, and their applicability and stability are greatly enhanced. After combining with the decomposition algorithm, even some simple models (such as MLR) can be used to accurately predict precipitation time series with complex variability patterns. Different model combinations and predictors lead to differences in prediction results among combined models. Therefore, more influencing factors (such as climate indicators) and more complex combined models based on the decomposition-prediction-reconstruction mode should be explored in future research to optimize the prediction model and prediction process, to further improve the prediction accuracy and reliability of the precipitation in this study area.
Abstract:
Since the 1960s, there is continuous groundwater exploitation in the North China Plain. With the rapid increase in water demand, groundwater overexploitation became an environmental geological problem. Recently, restrictions on groundwater exploitation and artificial groundwater recharge were developed to recover the groundwater level and remove the groundwater depression cone in Beijing-Tianjin-Hebei Plain. During the process of river ecological supplement, the recharge source of groundwater would be supplemented, and the water cycle mode could be changed. It is necessary to explain the groundwater depression cone evolution mechanism for accelerating the groundwater level recovery at this stage. Numerical simulation is the traditional method to study the groundwater depression cone variation, but the model operation and construction are relatively complex. With the development of computer science, many machine-learning algorithms are proposed. Because of its simplicity and efficiency, machine learning models are widely used in the hydrogeological research field. Eight specified indicators have been selected to study the variation of groundwater depression cones, considering from natural factors, human activity factors, and hydrology factors. With these indicators, the feature variable data set is formed, and based on the feature variable data set, three typical machine learning models are developed to distinguish the variation of the groundwater depression cone. The logistic regression (LR) model and support vector machine (SVM) model are based on the traditional machine learning algorithm, and random forest (RF) model is a kind of ensemble algorithm based on the tree models. The established models were evaluated by sensitivity, specificity, and R2 accuracy. The feature variable importance and shapely value were produced to quantify the contribution of each indicator to the groundwater depression cone and explain the behavior of each indicator. The results showed that the RF model outperforms the LR and SVM models in terms of model performance. The sensitivity of the RF model was 0.94, the specificity was 0.78, and the R2 accuracy was 0.88. It displayed that the RF model could be accurately identified both the groundwater depression cone area and the non-groundwater depression cone area. Model outputs suggested that the dominant influence indicator of the shallow groundwater depression cone was groundwater exploitation. Before 2018, the influence degree of groundwater pumping on the depression cone was about 50%. It played a positive role in the development of the groundwater depression cone. The river artificial recharge took 16% account for the variation of shallow groundwater depression cone development after 2018, and it had an obvious contribution to the groundwater level recovery. Two typical areas (Ningbailong area and Gaoliqing area) were selected to explore the evolution mechanism of groundwater depression cones in different regionals. The simulation results of the Ningbailong area and Gaoliqing area showed that the Ningbailong groundwater depression cone was governed by both precipitation and groundwater exploitation, the contribution rates for each indicator were 24% and 25%, respectively. Groundwater pumping dominated the development of the Gaoliqing groundwater depression cone, and it took 85% account for the evolution of the groundwater depression cone.In summary, three different data-driven models were constructed to study the variation of shallow groundwater depression cones in the whole North China Plain and two typical areas. The RF model was the optimal model. It was suitable for identifying the groundwater depression cone. The main control factor of the shallow groundwater depression cone was groundwater artificial exploitation. The river's artificial recharge could take an obvious positive impact on the recovery of groundwater level in the Ningbailong area. But it had little effect in the Gaoliqing area. Therefore, restrained groundwater exploitation by replacing agricultural groundwater could be the crucial way to restore groundwater depression in the Gaoliqing area.
Since the 1960s, there is continuous groundwater exploitation in the North China Plain. With the rapid increase in water demand, groundwater overexploitation became an environmental geological problem. Recently, restrictions on groundwater exploitation and artificial groundwater recharge were developed to recover the groundwater level and remove the groundwater depression cone in Beijing-Tianjin-Hebei Plain. During the process of river ecological supplement, the recharge source of groundwater would be supplemented, and the water cycle mode could be changed. It is necessary to explain the groundwater depression cone evolution mechanism for accelerating the groundwater level recovery at this stage. Numerical simulation is the traditional method to study the groundwater depression cone variation, but the model operation and construction are relatively complex. With the development of computer science, many machine-learning algorithms are proposed. Because of its simplicity and efficiency, machine learning models are widely used in the hydrogeological research field. Eight specified indicators have been selected to study the variation of groundwater depression cones, considering from natural factors, human activity factors, and hydrology factors. With these indicators, the feature variable data set is formed, and based on the feature variable data set, three typical machine learning models are developed to distinguish the variation of the groundwater depression cone. The logistic regression (LR) model and support vector machine (SVM) model are based on the traditional machine learning algorithm, and random forest (RF) model is a kind of ensemble algorithm based on the tree models. The established models were evaluated by sensitivity, specificity, and R2 accuracy. The feature variable importance and shapely value were produced to quantify the contribution of each indicator to the groundwater depression cone and explain the behavior of each indicator. The results showed that the RF model outperforms the LR and SVM models in terms of model performance. The sensitivity of the RF model was 0.94, the specificity was 0.78, and the R2 accuracy was 0.88. It displayed that the RF model could be accurately identified both the groundwater depression cone area and the non-groundwater depression cone area. Model outputs suggested that the dominant influence indicator of the shallow groundwater depression cone was groundwater exploitation. Before 2018, the influence degree of groundwater pumping on the depression cone was about 50%. It played a positive role in the development of the groundwater depression cone. The river artificial recharge took 16% account for the variation of shallow groundwater depression cone development after 2018, and it had an obvious contribution to the groundwater level recovery. Two typical areas (Ningbailong area and Gaoliqing area) were selected to explore the evolution mechanism of groundwater depression cones in different regionals. The simulation results of the Ningbailong area and Gaoliqing area showed that the Ningbailong groundwater depression cone was governed by both precipitation and groundwater exploitation, the contribution rates for each indicator were 24% and 25%, respectively. Groundwater pumping dominated the development of the Gaoliqing groundwater depression cone, and it took 85% account for the evolution of the groundwater depression cone.In summary, three different data-driven models were constructed to study the variation of shallow groundwater depression cones in the whole North China Plain and two typical areas. The RF model was the optimal model. It was suitable for identifying the groundwater depression cone. The main control factor of the shallow groundwater depression cone was groundwater artificial exploitation. The river's artificial recharge could take an obvious positive impact on the recovery of groundwater level in the Ningbailong area. But it had little effect in the Gaoliqing area. Therefore, restrained groundwater exploitation by replacing agricultural groundwater could be the crucial way to restore groundwater depression in the Gaoliqing area.
Abstract:
The co-transport of polycyclic aromatic hydrocarbons (PAHs) with bacterial colloids plays a facilitating role in the precise and efficient remediation of PAH pollution. It is crucial to establish an accurate and reliable numerical simulation model for the co-transport of PAHs and bacterial colloids. A numerical model was constructed for the co-transport of fluoranthene (a type of PAH) and bacterium FA1 using the Colloid-Facilitated Solute Transport (C-Ride) module in Hydrus. Uncertainties in the model parameters were analyzed through the Markov Chain Monte Carlo (MCMC) method, allowing for a quantitative depiction of the transport processes of fluoranthene influenced by water dynamics and microbial colloidal interactions.A series of indoor column experiments were conducted to investigate the transport of fluoranthene. The numerical model for the co-transport of fluoranthene and bacterium FA1 was constructed using the Hydrus C-Ride module. The MCMC method was applied to analyze parameter uncertainties, enabling a comprehensive understanding of the transport processes of fluoranthene under the influence of water dynamics and microbial colloidal interactions.The results demonstrated that bacterium FA1 enhanced the migration velocity of fluoranthene in the porous medium and increased the recovery rate of fluoranthene transport within the porous medium. The recovery rate increased from 55.06% to 76.16%. Specifically, the contribution of fluoranthene adsorbed onto mobile colloids and transported with water flow accounted for 41.46% and 34.69% of the recovery rate, respectively.The research findings hold both theoretical and practical significance in guiding the optimization design of microbial remediation strategies for groundwater pollution. The establishment of a numerical model provides a reliable tool for accurately characterizing the co-transport process of fluoranthene and bacterium FA1. These insights shed light on the understanding of PAH transport influenced by microbial colloidal interactions in porous media and contribute to the development of effective and efficient strategies for remediating PAH-contaminated groundwater.
The co-transport of polycyclic aromatic hydrocarbons (PAHs) with bacterial colloids plays a facilitating role in the precise and efficient remediation of PAH pollution. It is crucial to establish an accurate and reliable numerical simulation model for the co-transport of PAHs and bacterial colloids. A numerical model was constructed for the co-transport of fluoranthene (a type of PAH) and bacterium FA1 using the Colloid-Facilitated Solute Transport (C-Ride) module in Hydrus. Uncertainties in the model parameters were analyzed through the Markov Chain Monte Carlo (MCMC) method, allowing for a quantitative depiction of the transport processes of fluoranthene influenced by water dynamics and microbial colloidal interactions.A series of indoor column experiments were conducted to investigate the transport of fluoranthene. The numerical model for the co-transport of fluoranthene and bacterium FA1 was constructed using the Hydrus C-Ride module. The MCMC method was applied to analyze parameter uncertainties, enabling a comprehensive understanding of the transport processes of fluoranthene under the influence of water dynamics and microbial colloidal interactions.The results demonstrated that bacterium FA1 enhanced the migration velocity of fluoranthene in the porous medium and increased the recovery rate of fluoranthene transport within the porous medium. The recovery rate increased from 55.06% to 76.16%. Specifically, the contribution of fluoranthene adsorbed onto mobile colloids and transported with water flow accounted for 41.46% and 34.69% of the recovery rate, respectively.The research findings hold both theoretical and practical significance in guiding the optimization design of microbial remediation strategies for groundwater pollution. The establishment of a numerical model provides a reliable tool for accurately characterizing the co-transport process of fluoranthene and bacterium FA1. These insights shed light on the understanding of PAH transport influenced by microbial colloidal interactions in porous media and contribute to the development of effective and efficient strategies for remediating PAH-contaminated groundwater.
Abstract:
The carbon sequestration capacity of vegetation over 21 years (2000-2020) was analyzed using MODIS MOD17A3HGF datasets and the spatio-temporal evolution characteristics of net primary productivity (NPP) was investigated to explore the changing characteristics of terrestrial ecosystem health in the Songhua River basin under the condition of global climate change. The reaction of NPP to anomalous climate incidents was analyzed through using data on daily precipitation, maximum temperature, and minimum temperature from 80 regular meteorological stations situated in the Songhua River basin and its adjacent regions. The results could provide a scientific basis for quantifying the health of regional ecosystems in the context of climate change and for the development of measures to cope with extreme climate events. A variety of research methods were used such as correlation analysis, Mann-Kendall (M-K) test, GeoDetector, and relative importance ranking. The trend analysis techniques adopted encompassed one-way linear regression and Theil-Sen Median trend analysis. One-way linear regression was used to examine the linear trend of annual mean NPP within the Songhua River basin, while Theil-Sen Median trend analysis was used to examine the dynamic evolution of spatial patterns of NPP within the Songhua River basin. Pearson correlation coefficients was calculated based on pixel values to assess the relationship between vegetation NPP and extreme climate indices. The M-K test was utilized to establish the statistical significance of NPP trends, with the resulting outcome conveyed through the Z statistic. The GeoDetector parameter was employed, consisting of a "Factor detector", "Interaction detector", and "Risk detector", to explore the impact of extreme weather indices on vegetation NPP across the Songhua River basin. Multiple regression methods were utilized to investigate the effect of extreme climate indices on vegetation NPP in the Songhua River basin, considering both temporal and spatial scales. The results show that the average annual NPP within Songhua River basin showed an oscillating upward trend from 2000 to 2020, annually increasing at a rate of 4.82 g/m2 (calculated by C, same below). The annual NPP varied from 315.48 to 464.38 g/m2, annually averaging at 407.45 g/m2 over the 21 years. The maximum value occurred in 2014, reaching a peak of 464.38 g/m2, and the minimum value was observed in 2000 at 315.48 g/m2. Forest ecosystems had the highest mean annual NPP value, standing at 521.73 g/m2. Grassland and agroecosystems followed with the second-highest mean annual NPP values of 378.38 g/m2 and 343.26 g/m2, respectively. On the other hand, colony and wetland ecosystems had relatively lower mean annual NPP values, reaching 331.26 and 308.75 g/m2, respectively. The grassland ecosystem showed the most rapid growth rate, annually increasing by 5.64 g/m2 , closely followed by forest ecosystems, which exhibited an increase rate of 5.61 g/m2. In contrast, wetland ecosystems displayed the slowest increase rate at 3.44 g/m2. Regarding spatial distribution, the vegetation NPP within Songhua River basin showed an irregular pattern with high values in the southeast, low values in the southwest, high values in the surrounding areas, and low values in the central region. The areas with high annual mean NPP were mainly concentrated in Harbin City and Mudanjiang City in Heilongjiang Province and Jilin City, Yanbian Korean Autonomous Prefecture, and Baishan City in Jilin Province. In these areas, most of the flora displayed annual NPP values above 500 g/m2, with annual mean NPP levels also surpassing 500 g/m2. The strong positive correlation between the vegetation NPP and the extreme precipitation indices in the Songhua River basin was more significant than the corresponding negative correlations. Importantly, NPP illustrated predominant and statistically meaningful correlations with PRCPTOT,R10mm, and R95P. The significance of vegetation NPP in relation to extreme temperature events within Songhua River basin was relatively low, indicating that the extreme temperature indices did not significantly limit the ability of vegetation to sequester carbon compared to the extreme precipitation indices.
The carbon sequestration capacity of vegetation over 21 years (2000-2020) was analyzed using MODIS MOD17A3HGF datasets and the spatio-temporal evolution characteristics of net primary productivity (NPP) was investigated to explore the changing characteristics of terrestrial ecosystem health in the Songhua River basin under the condition of global climate change. The reaction of NPP to anomalous climate incidents was analyzed through using data on daily precipitation, maximum temperature, and minimum temperature from 80 regular meteorological stations situated in the Songhua River basin and its adjacent regions. The results could provide a scientific basis for quantifying the health of regional ecosystems in the context of climate change and for the development of measures to cope with extreme climate events. A variety of research methods were used such as correlation analysis, Mann-Kendall (M-K) test, GeoDetector, and relative importance ranking. The trend analysis techniques adopted encompassed one-way linear regression and Theil-Sen Median trend analysis. One-way linear regression was used to examine the linear trend of annual mean NPP within the Songhua River basin, while Theil-Sen Median trend analysis was used to examine the dynamic evolution of spatial patterns of NPP within the Songhua River basin. Pearson correlation coefficients was calculated based on pixel values to assess the relationship between vegetation NPP and extreme climate indices. The M-K test was utilized to establish the statistical significance of NPP trends, with the resulting outcome conveyed through the Z statistic. The GeoDetector parameter was employed, consisting of a "Factor detector", "Interaction detector", and "Risk detector", to explore the impact of extreme weather indices on vegetation NPP across the Songhua River basin. Multiple regression methods were utilized to investigate the effect of extreme climate indices on vegetation NPP in the Songhua River basin, considering both temporal and spatial scales. The results show that the average annual NPP within Songhua River basin showed an oscillating upward trend from 2000 to 2020, annually increasing at a rate of 4.82 g/m2 (calculated by C, same below). The annual NPP varied from 315.48 to 464.38 g/m2, annually averaging at 407.45 g/m2 over the 21 years. The maximum value occurred in 2014, reaching a peak of 464.38 g/m2, and the minimum value was observed in 2000 at 315.48 g/m2. Forest ecosystems had the highest mean annual NPP value, standing at 521.73 g/m2. Grassland and agroecosystems followed with the second-highest mean annual NPP values of 378.38 g/m2 and 343.26 g/m2, respectively. On the other hand, colony and wetland ecosystems had relatively lower mean annual NPP values, reaching 331.26 and 308.75 g/m2, respectively. The grassland ecosystem showed the most rapid growth rate, annually increasing by 5.64 g/m2 , closely followed by forest ecosystems, which exhibited an increase rate of 5.61 g/m2. In contrast, wetland ecosystems displayed the slowest increase rate at 3.44 g/m2. Regarding spatial distribution, the vegetation NPP within Songhua River basin showed an irregular pattern with high values in the southeast, low values in the southwest, high values in the surrounding areas, and low values in the central region. The areas with high annual mean NPP were mainly concentrated in Harbin City and Mudanjiang City in Heilongjiang Province and Jilin City, Yanbian Korean Autonomous Prefecture, and Baishan City in Jilin Province. In these areas, most of the flora displayed annual NPP values above 500 g/m2, with annual mean NPP levels also surpassing 500 g/m2. The strong positive correlation between the vegetation NPP and the extreme precipitation indices in the Songhua River basin was more significant than the corresponding negative correlations. Importantly, NPP illustrated predominant and statistically meaningful correlations with PRCPTOT,R10mm, and R95P. The significance of vegetation NPP in relation to extreme temperature events within Songhua River basin was relatively low, indicating that the extreme temperature indices did not significantly limit the ability of vegetation to sequester carbon compared to the extreme precipitation indices.
Abstract:
To implement the quality management and supervision (QMS) of hydraulic engineering projects, the Ministry of Water Resources of the People's Republic of China has formulated and issued the Measures of Supervision and Inspection of Hydraulic Engineering Quality and Work Safety , the Measures of Supervision and Inspection of Operations and Management of Hydraulic Engineering and the Measures of Supervision and Inspection of Hydraulic Engineering Contacts ("Three Measures" for short) for the supervision and inspection. The supervision and inspection work based on the "Three Measures" involves the QMS of the stakeholders and the hydraulic engineering projects. However, the related evaluation based on the "Three Measures" is qualitative, not quantitative. Thus, the QMS of hydraulic engineering projects needs to be improved, and a quantitative evaluation system is needed to compare different departments involved in the same project, different projects, and different provinces. Analytic hierarchy process (AHP for short) was selected for designing the evaluation system. The qualitative indicators in the "Three Measures" was taken as the quantitative indicators of the evaluation system. The evaluation indicator system was designed as seven layers, including 2,112 indicators which is in accordance with the "Three Measures". The indicators score system was designed combining the methods of the point-deduction system and the one-vote veto system. To improve the accuracy and reliability of the evaluation system, the weights of the indicator evaluation system was designed, compared, and selected. The importance of elements was divided into "normal", "important" and "critical", and the corresponding weight of the indicator of the evaluation system was set to one, three, and nine, respectively. The quantitative indicator evaluation system of QMS was established through the comprehensive index method using the selected weights and indicators score system. Additionally, this evaluation system of QMS has a flexible structure and can be spliced and deleted according to management requirements and the critical parts of supervision. The indicator evaluation system of "quality management" and "work safety management" were selected and established, and different hydraulic engineering projects were applied in seven provinces in China. These seven provinces were named A1 to A7 respectively. Two aspects of different stakeholders QMS in the projects and different projects QMS in different provinces were also evaluated. The quality management evaluation results of different stakeholders indicate that the level of the construction department is the highest, and the quality examination department and the building department are both at the lowest level. The evaluation results of work safety management in each stakeholder indicate that the construction department and the survey and design department are at the highest level, and the building department and the supervision department are at the lowest level. The evaluation scores of quality management in each province indicate that A2 and A7 are in the highest and lowest levels of quality management, respectively. The evaluation scores of work safety management in each province indicate that A6 and A5 were at the highest and lowest levels of work safety management, respectively. The comprehensive evaluation scores of quality management and work safety management in each province showed a tiered distribution, of which, 28.6% of the provinces were "excellent", 42.9% "good", and 28.6% "qualified", and no "unqualified" appeared.The average evaluation scores of work safety management were generally higher than those of quality management in provinces. The comprehensive scores indicated that the provinces were all above "qualified" and showed a three-tiered distribution. The scores had a large difference among these provinces. The quality and work safety management comprehensive analysis showed that the building departments were the most problematic in all provinces. The references can be provided to the hydraulic engineering projects QMS.
To implement the quality management and supervision (QMS) of hydraulic engineering projects, the Ministry of Water Resources of the People's Republic of China has formulated and issued the Measures of Supervision and Inspection of Hydraulic Engineering Quality and Work Safety , the Measures of Supervision and Inspection of Operations and Management of Hydraulic Engineering and the Measures of Supervision and Inspection of Hydraulic Engineering Contacts ("Three Measures" for short) for the supervision and inspection. The supervision and inspection work based on the "Three Measures" involves the QMS of the stakeholders and the hydraulic engineering projects. However, the related evaluation based on the "Three Measures" is qualitative, not quantitative. Thus, the QMS of hydraulic engineering projects needs to be improved, and a quantitative evaluation system is needed to compare different departments involved in the same project, different projects, and different provinces. Analytic hierarchy process (AHP for short) was selected for designing the evaluation system. The qualitative indicators in the "Three Measures" was taken as the quantitative indicators of the evaluation system. The evaluation indicator system was designed as seven layers, including 2,112 indicators which is in accordance with the "Three Measures". The indicators score system was designed combining the methods of the point-deduction system and the one-vote veto system. To improve the accuracy and reliability of the evaluation system, the weights of the indicator evaluation system was designed, compared, and selected. The importance of elements was divided into "normal", "important" and "critical", and the corresponding weight of the indicator of the evaluation system was set to one, three, and nine, respectively. The quantitative indicator evaluation system of QMS was established through the comprehensive index method using the selected weights and indicators score system. Additionally, this evaluation system of QMS has a flexible structure and can be spliced and deleted according to management requirements and the critical parts of supervision. The indicator evaluation system of "quality management" and "work safety management" were selected and established, and different hydraulic engineering projects were applied in seven provinces in China. These seven provinces were named A1 to A7 respectively. Two aspects of different stakeholders QMS in the projects and different projects QMS in different provinces were also evaluated. The quality management evaluation results of different stakeholders indicate that the level of the construction department is the highest, and the quality examination department and the building department are both at the lowest level. The evaluation results of work safety management in each stakeholder indicate that the construction department and the survey and design department are at the highest level, and the building department and the supervision department are at the lowest level. The evaluation scores of quality management in each province indicate that A2 and A7 are in the highest and lowest levels of quality management, respectively. The evaluation scores of work safety management in each province indicate that A6 and A5 were at the highest and lowest levels of work safety management, respectively. The comprehensive evaluation scores of quality management and work safety management in each province showed a tiered distribution, of which, 28.6% of the provinces were "excellent", 42.9% "good", and 28.6% "qualified", and no "unqualified" appeared.The average evaluation scores of work safety management were generally higher than those of quality management in provinces. The comprehensive scores indicated that the provinces were all above "qualified" and showed a three-tiered distribution. The scores had a large difference among these provinces. The quality and work safety management comprehensive analysis showed that the building departments were the most problematic in all provinces. The references can be provided to the hydraulic engineering projects QMS.
Abstract:
In recent years, China's hydropower resource development has been steadily progressing to high altitude and cold areas. Alpine areas have more complex conditions than mild climate areas, such as large temperature differences, extremely low temperatures, strong radiation, strong wind, and dryness. These complex conditions run throughout the dam's entire life cycle of construction, water storage, and operation, directly affecting the dam's safety and durability, introducing many safety risks such as cracking to the concrete dam and putting the dam's long-term operation safety to the test. Therefore, it is necessary to explore the law of strong seismic failure of concrete dams in the whole life cycle under complex cold conditions.The dynamic response analysis of dam is carried out by material deterioration test and numerical simulation method. Salt erosion, dry-wet cycle, and freeze-thaw cycle deterioration tests were carried out for different positions of the dam body. Through checking the environmental impact report of Yalong River hydropower station, content of each ion in the water can be obtained to configure the salt solution. To shorten the failure time of the specimen, a 10-fold concentration of complex salt solution is configured in the laboratory. The concrete specimens were successively put into the sulfate resistance cycle testing machine and freeze-thaw testing machine for salt immersion-dry and wet-freeze-thaw cycle test, first 4 salt immersion + dry and wet cycles (soaking for 15 h, drying at 80 ℃± 5 ℃ for 9 hours, which is a salt immersion-dry and wet cycle), taking 4 days, and then 25 freeze-thaw cycles (freezing at ?18℃±2 ℃ for 2 h, melting at 5 ℃±2 ℃ for 2 h, for one freeze-thaw cycle), taking 4 days. A full salt-dip-wet-freeze-thaw cycle, or large cycle, takes 8 days, and the compressive strength, mass loss, and kinetic elastic modulus of concrete are measured after each large cycle. Based on the material test results, the numerical model of gravity dam was established by ABAQUS finite element software, and the element type adopted 4-node bilinear plane stress quadrilateral reduced integral element (CPS4R), with a total of 23,189 elements in the model, and the hydrodynamic pressure was applied in the form of additional mass and artificially excited. The occurrence, development, and collapse failure of concrete dams under strong seismic stimulation before and after the deterioration of salt-immersion-wet-freeze-thaw cycles of concrete materials is simulated.The research showed that: (1) The three factors of salt leaching erosion, dry and wet cycle, and freeze-thaw cycle all lead to concrete deterioration and reduce mechanical properties to varying degrees. The combination of three factors causes the most serious deterioration of concrete, followed by the impact of the freeze-thaw cycle. (2) In the vicinity of the normal water storage level upstream, due to the coupling of three factors, the deterioration of concrete here is significant, and its strength, the elastic modulus and the mass loss decrease. (3) The deterioration of concrete reduces the seismic bearing capacity of the dam structure, and the cracking acceleration decreases by 19.53%. (4) The deterioration of concrete materials has changed the stress distribution pattern of the dam body and even caused collapse.When designing gravity dams in alpine regions, the durability of concrete requires special consideration. During the life cycle of a dam, it is necessary to take timely and appropriate maintenance measures for the vulnerable location of concrete.
In recent years, China's hydropower resource development has been steadily progressing to high altitude and cold areas. Alpine areas have more complex conditions than mild climate areas, such as large temperature differences, extremely low temperatures, strong radiation, strong wind, and dryness. These complex conditions run throughout the dam's entire life cycle of construction, water storage, and operation, directly affecting the dam's safety and durability, introducing many safety risks such as cracking to the concrete dam and putting the dam's long-term operation safety to the test. Therefore, it is necessary to explore the law of strong seismic failure of concrete dams in the whole life cycle under complex cold conditions.The dynamic response analysis of dam is carried out by material deterioration test and numerical simulation method. Salt erosion, dry-wet cycle, and freeze-thaw cycle deterioration tests were carried out for different positions of the dam body. Through checking the environmental impact report of Yalong River hydropower station, content of each ion in the water can be obtained to configure the salt solution. To shorten the failure time of the specimen, a 10-fold concentration of complex salt solution is configured in the laboratory. The concrete specimens were successively put into the sulfate resistance cycle testing machine and freeze-thaw testing machine for salt immersion-dry and wet-freeze-thaw cycle test, first 4 salt immersion + dry and wet cycles (soaking for 15 h, drying at 80 ℃± 5 ℃ for 9 hours, which is a salt immersion-dry and wet cycle), taking 4 days, and then 25 freeze-thaw cycles (freezing at ?18℃±2 ℃ for 2 h, melting at 5 ℃±2 ℃ for 2 h, for one freeze-thaw cycle), taking 4 days. A full salt-dip-wet-freeze-thaw cycle, or large cycle, takes 8 days, and the compressive strength, mass loss, and kinetic elastic modulus of concrete are measured after each large cycle. Based on the material test results, the numerical model of gravity dam was established by ABAQUS finite element software, and the element type adopted 4-node bilinear plane stress quadrilateral reduced integral element (CPS4R), with a total of 23,189 elements in the model, and the hydrodynamic pressure was applied in the form of additional mass and artificially excited. The occurrence, development, and collapse failure of concrete dams under strong seismic stimulation before and after the deterioration of salt-immersion-wet-freeze-thaw cycles of concrete materials is simulated.The research showed that: (1) The three factors of salt leaching erosion, dry and wet cycle, and freeze-thaw cycle all lead to concrete deterioration and reduce mechanical properties to varying degrees. The combination of three factors causes the most serious deterioration of concrete, followed by the impact of the freeze-thaw cycle. (2) In the vicinity of the normal water storage level upstream, due to the coupling of three factors, the deterioration of concrete here is significant, and its strength, the elastic modulus and the mass loss decrease. (3) The deterioration of concrete reduces the seismic bearing capacity of the dam structure, and the cracking acceleration decreases by 19.53%. (4) The deterioration of concrete materials has changed the stress distribution pattern of the dam body and even caused collapse.When designing gravity dams in alpine regions, the durability of concrete requires special consideration. During the life cycle of a dam, it is necessary to take timely and appropriate maintenance measures for the vulnerable location of concrete.
Comparison of efficient testing methods for compaction quality in hydraulic engineering construction
Abstract:
The cutting ring method was compared with the Platts penetration method, the nuclear densitometer method, and the harmonic method in Juma River flood control project in the south of Xiong'an New Area (Rongcheng section). The harmonic approach captures the equivalent acceleration signal using an acceleration sensor positioned on the rolling wheel, which is then filtered and Fourier transformed into a frequency domain signal. The test area adopts the construction technology of static rolling twice and vibration rolling six times to roll the test area. After each vibration rolling, the rolling area is sampled once, with a total of 15 sampling points. When the number of rolls increases, shift 0.5 m along the axis direction of the rolling track and draw a line at the sampling boundary to make a mark. On the same number of rolling paths, along the axis direction of the rolling trajectory, the compaction degree of the fill near a certain point was measured every 6 m using the cutting ring method, Platts penetration method, nuclear densitometer method, and harmonic method. The average relative error (EMR), standardized root mean square error ( ENRMS), determination coefficient (R2), and consistency index (IA ) were used to evaluate the differences between various methods with the cutting ring method, and a linear equation was used to establish the relationship between various methods with the cutting ring method. The results showed that with the increase in rolling times, the compaction degree by the cutting ring method showed an increasing trend. After 2 or 3 times of vibration rolling, the compaction degree of the soil has reached the project’s specification requirements for the filling design. With the increase in rolling times, the soil compaction degree was stable, and the compaction degree would fluctuate slightly. The results of the Pratt penetration method were not much different from those of the cutting ring method, and the relative error was controlled within ±10%. The Platts penetration method and harmonic method could establish a good correlation with the cutting ring method, and the correlation coefficient R2 of the linear equation was greater than 0.95, while the nuclear densitometer method had poor performance in the test, and the correlation coefficient R2 of the linear equation was only 0.37. The results could provide technical support for the rapid detection of compaction quality and the application of intelligent rolling technology in hydraulic engineering.
The cutting ring method was compared with the Platts penetration method, the nuclear densitometer method, and the harmonic method in Juma River flood control project in the south of Xiong'an New Area (Rongcheng section). The harmonic approach captures the equivalent acceleration signal using an acceleration sensor positioned on the rolling wheel, which is then filtered and Fourier transformed into a frequency domain signal. The test area adopts the construction technology of static rolling twice and vibration rolling six times to roll the test area. After each vibration rolling, the rolling area is sampled once, with a total of 15 sampling points. When the number of rolls increases, shift 0.5 m along the axis direction of the rolling track and draw a line at the sampling boundary to make a mark. On the same number of rolling paths, along the axis direction of the rolling trajectory, the compaction degree of the fill near a certain point was measured every 6 m using the cutting ring method, Platts penetration method, nuclear densitometer method, and harmonic method. The average relative error (EMR), standardized root mean square error ( ENRMS), determination coefficient (R2), and consistency index (IA ) were used to evaluate the differences between various methods with the cutting ring method, and a linear equation was used to establish the relationship between various methods with the cutting ring method. The results showed that with the increase in rolling times, the compaction degree by the cutting ring method showed an increasing trend. After 2 or 3 times of vibration rolling, the compaction degree of the soil has reached the project’s specification requirements for the filling design. With the increase in rolling times, the soil compaction degree was stable, and the compaction degree would fluctuate slightly. The results of the Pratt penetration method were not much different from those of the cutting ring method, and the relative error was controlled within ±10%. The Platts penetration method and harmonic method could establish a good correlation with the cutting ring method, and the correlation coefficient R2 of the linear equation was greater than 0.95, while the nuclear densitometer method had poor performance in the test, and the correlation coefficient R2 of the linear equation was only 0.37. The results could provide technical support for the rapid detection of compaction quality and the application of intelligent rolling technology in hydraulic engineering.
QIU?Jianchun
1，LONG?Changlin
1，ZHENG?Dongjian
2, 3, 4，WU?Hao
5，DING?Yue
6，ZHANG?Hailong
7，
XU?Pengcheng
1，CHEN?Xingqiao
2, 3, 4，YUAN?Cong
6
Abstract:
The dynamic model test of an arch dam on a shaking table is an important way to study its seismic performance and failure mode. A shaking table damage model test of the arch dam was carried out. A model material primarily composed of barite sand, barite powder, and cement was made. The model material had material possesses characteristics of high density, low dynamic elastic modulus, and appropriate strength, with its average density being 3,175 kg/m3 , average dynamic elastic modulus being 1.05 GPa and average tensile strength being 68.7 kPa. Combining the conditions provided by the selected shaking table and the mechanical properties of the used model material, the arch dam model was designed with four parts: dam body, foundation, dam shoulder, and boundary wall. The height of the dam body, the maximum width of the dam crest, the thickness of the dam crest, and the thickness at the base of the dam body were 1.5 m, 1.0 m, 6 cm, and 11 cm, respectively. The total mass of the arch dam model was 2.17 t.Pressure-resistant accelerometers and resistance strain gauges were arranged at different parts and elevations of the arch dam model to obtain dynamic responses. The structural dynamic responses of the model under different earthquake simulation loads were tested. A specific working condition (Time period was 32.0 s) of the arch dam model was selected for analysis, in which the structure began to exhibit evident damage with visible cracks in arch crown and gradually progressed. By analyzing the structural dynamic strain responses under following working condition, the time of the damage occurrence was determined at t=5.8 s, and the condition was divided into four periods. Multiple acceleration response measurement points on the arch crown beam were selected for analysis. The acceleration amplification factors at the acceleration measurement points near the arch crown showed a noticeable and gradually increasing trend in four time periods, consistent with the characteristic of significant cracks appearing in the middle part of the arch crown.The subspace numerical algorithm for modal parameter identification (N4SID method) and the ARX model identification method were introduced. Based on the collected dynamic response measurements, the identification of natural frequencies and damping ratios of the arch dam model structure were conducted for four different periods by the introduced two methods. It was observed that both methods yielded small errors in identifying natural frequencies at each order, while there was a significant difference in the identified damping ratios. This discrepancy was primarily attributed to the high complexity of the damping characteristics of the arch dam structure. Comparing the identified values of natural frequencies and damping ratios at each order for the four time periods, it was found that the natural frequencies gradually decreased with the development of structural damage, while the damping ratios increased with the development of structural damage. The identification results were consistent with the strain response process and the actual damage results of the arch dam model, validating the effectiveness of the dynamic characteristic parameter identification. The results provided a valuable reference for the preparation and analysis of arch dam shaking table tests. Additionally, this study can also serve as validation material for the identification of dynamic characteristic parameters and damage diagnosis methods in arch dam structures.
The dynamic model test of an arch dam on a shaking table is an important way to study its seismic performance and failure mode. A shaking table damage model test of the arch dam was carried out. A model material primarily composed of barite sand, barite powder, and cement was made. The model material had material possesses characteristics of high density, low dynamic elastic modulus, and appropriate strength, with its average density being 3,175 kg/m3 , average dynamic elastic modulus being 1.05 GPa and average tensile strength being 68.7 kPa. Combining the conditions provided by the selected shaking table and the mechanical properties of the used model material, the arch dam model was designed with four parts: dam body, foundation, dam shoulder, and boundary wall. The height of the dam body, the maximum width of the dam crest, the thickness of the dam crest, and the thickness at the base of the dam body were 1.5 m, 1.0 m, 6 cm, and 11 cm, respectively. The total mass of the arch dam model was 2.17 t.Pressure-resistant accelerometers and resistance strain gauges were arranged at different parts and elevations of the arch dam model to obtain dynamic responses. The structural dynamic responses of the model under different earthquake simulation loads were tested. A specific working condition (Time period was 32.0 s) of the arch dam model was selected for analysis, in which the structure began to exhibit evident damage with visible cracks in arch crown and gradually progressed. By analyzing the structural dynamic strain responses under following working condition, the time of the damage occurrence was determined at t=5.8 s, and the condition was divided into four periods. Multiple acceleration response measurement points on the arch crown beam were selected for analysis. The acceleration amplification factors at the acceleration measurement points near the arch crown showed a noticeable and gradually increasing trend in four time periods, consistent with the characteristic of significant cracks appearing in the middle part of the arch crown.The subspace numerical algorithm for modal parameter identification (N4SID method) and the ARX model identification method were introduced. Based on the collected dynamic response measurements, the identification of natural frequencies and damping ratios of the arch dam model structure were conducted for four different periods by the introduced two methods. It was observed that both methods yielded small errors in identifying natural frequencies at each order, while there was a significant difference in the identified damping ratios. This discrepancy was primarily attributed to the high complexity of the damping characteristics of the arch dam structure. Comparing the identified values of natural frequencies and damping ratios at each order for the four time periods, it was found that the natural frequencies gradually decreased with the development of structural damage, while the damping ratios increased with the development of structural damage. The identification results were consistent with the strain response process and the actual damage results of the arch dam model, validating the effectiveness of the dynamic characteristic parameter identification. The results provided a valuable reference for the preparation and analysis of arch dam shaking table tests. Additionally, this study can also serve as validation material for the identification of dynamic characteristic parameters and damage diagnosis methods in arch dam structures.
Abstract:
The Yangtze-to-Huaihe River Water Diversion Project (Henan Section) is located in the eastern part of Henan Province, and its water consumption affects many elements of life, including agricultural irrigation, industry, and the environment. The carrying capacity of water resources is incompatible with the distribution of population and cultivated land. There are issues such as low per capita average water per mu, industrial water crowding out other water uses, and complex engineering measures, coupled with the congenital scarcity of water resources. The contradiction between supply and demand for water resources in the water-affected area is tense, and the paradox between people and water is growing. However, the current researches rarely take the human-water relationship into account in the optimization goal, and the configuration results may cause human-water disharmony. The project has been opened to water, but there is currently no supporting allocation system in the Henan section, and how to incorporate the concept of harmonious water allocation into the optimal allocation system of water resources to alleviate the contradiction between people and water in the water-affected areas, improve the ecological environment, and drive economic growth is an urgent problem to be solved.To strengthen the unified allocation of water resources, based on the model of separate development of Spring Boot and Vue front-end and back-end, the water resources allocation system of the Henan section was designed and developed by Tianditu API, WebGL, Echarts, Lingo and other technologies. Among them, the front-end framework was built by Vue framework, Tianditu API, WebGL, and Echarts technology, and the main functions are model parameter input and data visualization. The back-end framework was built using Spring Boot and Lingo technology, and the main functions are the solution of water resource allocation models and data persistence. The advantage of this front-end and back-end development of system separation is that the development weight of the entire project is shifted forward, and the front-end and back-end developers can develop together, to improve the efficiency of system research and development, truly realizing the decoupling of the front-end and back-end of the system, separates dynamic and static resources, improves the scalability of the system, and facilitates the secondary development of the water resource allocation system.The system design ideas and implementation process were discussed from the three perspectives of system design, functional interface, and key technology, to realize the functions of geographic information service, supply and demand water forecast, annual harmonious allocation of water resources, monthly scheduling scheme of engineering, and scheduling of abnormal working conditions, and realize the visualization of water allocation, intelligent operation scheduling, and integration of cross-basin water diversion management and control.The establishment of the water resources allocation system of the Henan section has improved the level of refined management of water resources in the receiving area, solved the multi-source, multi-target, and multi-department allocation problem of the cross-basin water diversion project, and provided effective technical support for the efficient utilization of water resources in the Yangtze to Huaihe River Water Diversion (Henan section).
The Yangtze-to-Huaihe River Water Diversion Project (Henan Section) is located in the eastern part of Henan Province, and its water consumption affects many elements of life, including agricultural irrigation, industry, and the environment. The carrying capacity of water resources is incompatible with the distribution of population and cultivated land. There are issues such as low per capita average water per mu, industrial water crowding out other water uses, and complex engineering measures, coupled with the congenital scarcity of water resources. The contradiction between supply and demand for water resources in the water-affected area is tense, and the paradox between people and water is growing. However, the current researches rarely take the human-water relationship into account in the optimization goal, and the configuration results may cause human-water disharmony. The project has been opened to water, but there is currently no supporting allocation system in the Henan section, and how to incorporate the concept of harmonious water allocation into the optimal allocation system of water resources to alleviate the contradiction between people and water in the water-affected areas, improve the ecological environment, and drive economic growth is an urgent problem to be solved.To strengthen the unified allocation of water resources, based on the model of separate development of Spring Boot and Vue front-end and back-end, the water resources allocation system of the Henan section was designed and developed by Tianditu API, WebGL, Echarts, Lingo and other technologies. Among them, the front-end framework was built by Vue framework, Tianditu API, WebGL, and Echarts technology, and the main functions are model parameter input and data visualization. The back-end framework was built using Spring Boot and Lingo technology, and the main functions are the solution of water resource allocation models and data persistence. The advantage of this front-end and back-end development of system separation is that the development weight of the entire project is shifted forward, and the front-end and back-end developers can develop together, to improve the efficiency of system research and development, truly realizing the decoupling of the front-end and back-end of the system, separates dynamic and static resources, improves the scalability of the system, and facilitates the secondary development of the water resource allocation system.The system design ideas and implementation process were discussed from the three perspectives of system design, functional interface, and key technology, to realize the functions of geographic information service, supply and demand water forecast, annual harmonious allocation of water resources, monthly scheduling scheme of engineering, and scheduling of abnormal working conditions, and realize the visualization of water allocation, intelligent operation scheduling, and integration of cross-basin water diversion management and control.The establishment of the water resources allocation system of the Henan section has improved the level of refined management of water resources in the receiving area, solved the multi-source, multi-target, and multi-department allocation problem of the cross-basin water diversion project, and provided effective technical support for the efficient utilization of water resources in the Yangtze to Huaihe River Water Diversion (Henan section).
Abstract:
Most spillways in engineering projects included several curved sections, and the water flow in the curved sections was affected by inertial and centrifugal forces, causing the water flow to gather on the concave bank and jeopardizing the spillway's security. The rough strip energy dissipators could effectively improve this phenomenon, making it important to study the flow characteristics of continuous curved spillways and the hydraulic characteristics of the rough strip energy dissipators. To explore the flow characteristics of continuous curved spillways and the hydraulic characteristics of the rough strip energy dissipators, 27 sets of orthogonal model tests were carried out. The optimal working conditions were selected by the energy dissipation rate and ultra-high variation coefficient, and the RNGk-ε turbulent flow model and volume of fluid method were combined to compare the flow characteristics of the spillway with and without the rough strip energy dissipators.The results showed that the water depth along the path increased and changed sharply due to the rough strip energy dissipators. The rough strip energy dissipators could inhibit the generation of rhomboid wave and fold flow, by improving the flow pattern in the two curved sections to enhance the water surface uniformity by 38% and 44.7%. The average longitudinal velocity in the two curved sections was reduced by 45.16% and 44.83% by the rough strip energy dissipators, and the maximum longitudinal velocity of the concave banks in the two sections moved downward along the water depth. The turbulent flow in the two curved sections intensified due to the influence of the rough strip energy dissipators, causing the average longitudinal turbulent intensity to increase by 117.98% and 71.05%, respectively. The longitudinal turbulent intensity mostly attenuated on the concave bank and increased on the convex bank, the maximum longitudinal turbulent intensity of each section of the concave bank moved upward along the water depth. The rough strip energy dissipators also increased the hydrodynamic pressure of the bed surface, reduced the pressure difference between the two sides, significantly improved the pressure distribution form, and protected the bottom plate and the side wall from erosion.Based on the research results, it could be concluded that from the perspective of water level, velocity, turbulence intensity, and hydrodynamic pressure of the bed surface, adding the rough strip energy dissipators at the bottom of the spillway continuous bend could stabilize the flow, reduce the energy and reduce the erosion of water flow on the concave bank. The research results could provide a reference for the design and safe operation of similar spillway continuous bends.
Most spillways in engineering projects included several curved sections, and the water flow in the curved sections was affected by inertial and centrifugal forces, causing the water flow to gather on the concave bank and jeopardizing the spillway's security. The rough strip energy dissipators could effectively improve this phenomenon, making it important to study the flow characteristics of continuous curved spillways and the hydraulic characteristics of the rough strip energy dissipators. To explore the flow characteristics of continuous curved spillways and the hydraulic characteristics of the rough strip energy dissipators, 27 sets of orthogonal model tests were carried out. The optimal working conditions were selected by the energy dissipation rate and ultra-high variation coefficient, and the RNGk-ε turbulent flow model and volume of fluid method were combined to compare the flow characteristics of the spillway with and without the rough strip energy dissipators.The results showed that the water depth along the path increased and changed sharply due to the rough strip energy dissipators. The rough strip energy dissipators could inhibit the generation of rhomboid wave and fold flow, by improving the flow pattern in the two curved sections to enhance the water surface uniformity by 38% and 44.7%. The average longitudinal velocity in the two curved sections was reduced by 45.16% and 44.83% by the rough strip energy dissipators, and the maximum longitudinal velocity of the concave banks in the two sections moved downward along the water depth. The turbulent flow in the two curved sections intensified due to the influence of the rough strip energy dissipators, causing the average longitudinal turbulent intensity to increase by 117.98% and 71.05%, respectively. The longitudinal turbulent intensity mostly attenuated on the concave bank and increased on the convex bank, the maximum longitudinal turbulent intensity of each section of the concave bank moved upward along the water depth. The rough strip energy dissipators also increased the hydrodynamic pressure of the bed surface, reduced the pressure difference between the two sides, significantly improved the pressure distribution form, and protected the bottom plate and the side wall from erosion.Based on the research results, it could be concluded that from the perspective of water level, velocity, turbulence intensity, and hydrodynamic pressure of the bed surface, adding the rough strip energy dissipators at the bottom of the spillway continuous bend could stabilize the flow, reduce the energy and reduce the erosion of water flow on the concave bank. The research results could provide a reference for the design and safe operation of similar spillway continuous bends.
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Abstract:
The Middle Route of South to North Water Diversion Project (MRP) has long canals, involves many areas and hydraulic structures, transfers water by a huge amount, and has various working conditions. These all bring great difficulties to the regulation, control, and management of the project. The technical problem of the engineering lies in the fact that the scientific and mechanism problems behind it are not fully revealed and solved, including multi-dimensional equilibrium control mechanism of multiple water sources under changing conditions, multi-process coupling mechanism of water quantity and water quality, emergency scheduling model for multi-material water pollution, hydraulic response mechanism and control of open channel under multi-gate joint application. In order to establish a complete set of technical system to support its scheduling, this paper summarizes the existing research on the five key points of forecast, scheduling, simulation, control, and evaluation. And on the basis of summarizing the previous research, the key technologies awaiting urgent research are explained in detail, including forecast and scheduling in water source areas and water-receiving areas, multi-phase simulation of water pollution, water quality and water quality control, automatic control technology, evaluation technology, and platform construction. Finally, the paper discusses the scientific problems to be solved in order to realize the intelligent regulation and emergency regulation for the MRP and makes a summary of the research.
The Middle Route of South to North Water Diversion Project (MRP) has long canals, involves many areas and hydraulic structures, transfers water by a huge amount, and has various working conditions. These all bring great difficulties to the regulation, control, and management of the project. The technical problem of the engineering lies in the fact that the scientific and mechanism problems behind it are not fully revealed and solved, including multi-dimensional equilibrium control mechanism of multiple water sources under changing conditions, multi-process coupling mechanism of water quantity and water quality, emergency scheduling model for multi-material water pollution, hydraulic response mechanism and control of open channel under multi-gate joint application. In order to establish a complete set of technical system to support its scheduling, this paper summarizes the existing research on the five key points of forecast, scheduling, simulation, control, and evaluation. And on the basis of summarizing the previous research, the key technologies awaiting urgent research are explained in detail, including forecast and scheduling in water source areas and water-receiving areas, multi-phase simulation of water pollution, water quality and water quality control, automatic control technology, evaluation technology, and platform construction. Finally, the paper discusses the scientific problems to be solved in order to realize the intelligent regulation and emergency regulation for the MRP and makes a summary of the research.
Abstract:
Based on the T OE theor et ical fr amewo rk ( T echnolo gy2 Or ganizatio n2Environment) and the specific situation of smart water co nstr uction, the TOE framew ork w hich affects smart water constructio n was developed, and the effect s of each impact facto r o n the construction and development o f smar t w ater wer e analyzed from the technical, o rg anizat ional, and env iro nmental dimensions. T he technical dimensio n factors include the technica l superio rity, complex it y, compatibility , and o bser vability. T he org anizational dimension factor s include the const ruction necessity, demand urg ency , and co nstr uction feasibility . The envir on2 mental dimension factor s include the support sy st em, standard system, and info rmation securit y. On the basis, analyt ic hierarchy pr ocess ( AH P) w as used to determine the pr ior ity of the impact facto rs. The results showed that the or ganizatio nal dimensio n facto rs and technical dimension fact ors have hig h impacts on smart water construction w ith the weig ht o f 49% and 31% o ver the index system respect ively. Amo ng the impact factor s, const ruct ion necessity has the hig hest weig ht ( 25%) , follow ed by technical super io rit y ( 16%) , demand urg ency ( 12%) , and construction feasibility ( 12%) . The r esear ch pr ov ides an effectiv ely new metho d fo r the quantitative analy sis of impact factor s of smar t w ater const ruct ion, and the evaluation r esult s can prov ide import ant r eference fo r decision2making of w ater secto r and develo pment of w ater business.
Based on the T OE theor et ical fr amewo rk ( T echnolo gy2 Or ganizatio n2Environment) and the specific situation of smart water co nstr uction, the TOE framew ork w hich affects smart water constructio n was developed, and the effect s of each impact facto r o n the construction and development o f smar t w ater wer e analyzed from the technical, o rg anizat ional, and env iro nmental dimensions. T he technical dimensio n factors include the technica l superio rity, complex it y, compatibility , and o bser vability. T he org anizational dimension factor s include the const ruction necessity, demand urg ency , and co nstr uction feasibility . The envir on2 mental dimension factor s include the support sy st em, standard system, and info rmation securit y. On the basis, analyt ic hierarchy pr ocess ( AH P) w as used to determine the pr ior ity of the impact facto rs. The results showed that the or ganizatio nal dimensio n facto rs and technical dimension fact ors have hig h impacts on smart water construction w ith the weig ht o f 49% and 31% o ver the index system respect ively. Amo ng the impact factor s, const ruct ion necessity has the hig hest weig ht ( 25%) , follow ed by technical super io rit y ( 16%) , demand urg ency ( 12%) , and construction feasibility ( 12%) . The r esear ch pr ov ides an effectiv ely new metho d fo r the quantitative analy sis of impact factor s of smar t w ater const ruct ion, and the evaluation r esult s can prov ide import ant r eference fo r decision2making of w ater secto r and develo pment of w ater business.
Abstract:
Using precipitation and temperature for the period of 1851-2008 of Xi'an city, the paper analyzed the variation trends and abrupt changes of hydro-meteorological factors including precipitation and temperature using linear fitting, sliding t test, ordered clustering and Mann-Kendall methods．Firstly, the variation trends of precipitation and temperature were analyzed using linear fitting and anomaly percentage, and then the change characteristic of number of rainy days and precipitation were further analyzed. Finally, the paper investigated the abrupt changes of precipitation and temperature using sliding t test, ordered clustering and Mann-Kendall methods. The results showed that the precipitation decreased gradually. Precipitation accounts for 58% of annual precipitation during the flood season and the annual precipitation distribution is uneven. The annual mean temperature and extreme minimum temperature have increased. The abrupt changes of the precipitation were detected in 1958、1975 and 1980, and the abrupt changes of annual average temperature have found between 1993-1995.
Using precipitation and temperature for the period of 1851-2008 of Xi'an city, the paper analyzed the variation trends and abrupt changes of hydro-meteorological factors including precipitation and temperature using linear fitting, sliding t test, ordered clustering and Mann-Kendall methods．Firstly, the variation trends of precipitation and temperature were analyzed using linear fitting and anomaly percentage, and then the change characteristic of number of rainy days and precipitation were further analyzed. Finally, the paper investigated the abrupt changes of precipitation and temperature using sliding t test, ordered clustering and Mann-Kendall methods. The results showed that the precipitation decreased gradually. Precipitation accounts for 58% of annual precipitation during the flood season and the annual precipitation distribution is uneven. The annual mean temperature and extreme minimum temperature have increased. The abrupt changes of the precipitation were detected in 1958、1975 and 1980, and the abrupt changes of annual average temperature have found between 1993-1995.
Abstract:
Sensitivity analysis was performed to analyze the inputs and outputs of the complex model and system qualitatively and quantitatively, which can benefit the inspection of model structure, identification of model parameters, and model application. In this paper, Sobol method was applied to evaluate the sensitivity of single parameter and multiple parameters of the model in the Huanren reservoir catchment. The objective functions of sensitivity analysis included the deterministic coefficients and error coefficients of total water, low flow, and high flow. The results showed that the sensitivity of parameters was different under different objective functions, and Sobol method can provide the sensitivity for all parameters and sensitivity between each parameter, which is useful for sensitivity analysis of hydrological models.
Sensitivity analysis was performed to analyze the inputs and outputs of the complex model and system qualitatively and quantitatively, which can benefit the inspection of model structure, identification of model parameters, and model application. In this paper, Sobol method was applied to evaluate the sensitivity of single parameter and multiple parameters of the model in the Huanren reservoir catchment. The objective functions of sensitivity analysis included the deterministic coefficients and error coefficients of total water, low flow, and high flow. The results showed that the sensitivity of parameters was different under different objective functions, and Sobol method can provide the sensitivity for all parameters and sensitivity between each parameter, which is useful for sensitivity analysis of hydrological models.
Abstract:
Accurate and rapid determination of the distribution of contaminants is the main task for the investigation work of a contaminated site. As a new surveying tool for contaminated sites, direct push technology can be used for soil sample collection in the vadoze zone and aquifer, detection of aquifer parameters, and determination of pollutants. It has the advantages of fast, accurate, and free of cross-contamination. In this paper, the development and research progress of direct push technology was introduced, and the technology innovation was discussed.
Accurate and rapid determination of the distribution of contaminants is the main task for the investigation work of a contaminated site. As a new surveying tool for contaminated sites, direct push technology can be used for soil sample collection in the vadoze zone and aquifer, detection of aquifer parameters, and determination of pollutants. It has the advantages of fast, accurate, and free of cross-contamination. In this paper, the development and research progress of direct push technology was introduced, and the technology innovation was discussed.
Abstract:
"National River Linking Project (NRLP)" is a large-scale hydraulic engineering project that aims to reduce the persistent water shortage problems in India. In, this paper, describes the target planning and progress of the NRLPNational River Linking Project, was described, and introduces the program’s management system of this project and water policy in India was introduced. Due to the large scale of the project, it involves involved the deployment and utilization of water resources and utilization inof the many rivers of the South Peninsula, therefore several problems exist in the implementation of the project such as the funding stress, international development of transboundary rivers, and ecological environment. this paper addresses and analyzes the basic problems based on the project’s main benefit goals.
"National River Linking Project (NRLP)" is a large-scale hydraulic engineering project that aims to reduce the persistent water shortage problems in India. In, this paper, describes the target planning and progress of the NRLPNational River Linking Project, was described, and introduces the program’s management system of this project and water policy in India was introduced. Due to the large scale of the project, it involves involved the deployment and utilization of water resources and utilization inof the many rivers of the South Peninsula, therefore several problems exist in the implementation of the project such as the funding stress, international development of transboundary rivers, and ecological environment. this paper addresses and analyzes the basic problems based on the project’s main benefit goals.
Abstract:
Environmental Kuznets Curve (EKC) hypothesis has instructive significance to explore the relationship between environmental protection and economic development and to seek the coordinated development of economy and environment. Based on the analysis of the basic conception of EKC hypothesis, the research progress of the impact factors, theoretical developments, and empirical studies of EKC were illustrated in this paper, and the existing problems of the hypothesis were also discussed. Finally, it was noted that under the international trade conditions, the developing countries should study the clean technology, policy reformation, public education, and environmental law system from the developed countries, which can help them decrease the EKC turn point, flatten EKC curve, and seek for win-win relationship between economy and environment.
Environmental Kuznets Curve (EKC) hypothesis has instructive significance to explore the relationship between environmental protection and economic development and to seek the coordinated development of economy and environment. Based on the analysis of the basic conception of EKC hypothesis, the research progress of the impact factors, theoretical developments, and empirical studies of EKC were illustrated in this paper, and the existing problems of the hypothesis were also discussed. Finally, it was noted that under the international trade conditions, the developing countries should study the clean technology, policy reformation, public education, and environmental law system from the developed countries, which can help them decrease the EKC turn point, flatten EKC curve, and seek for win-win relationship between economy and environment.
Abstract:
The analysis of the night minimum flow data in the Districted Metered Area (DMA) of the water distribution system can characterize the real loss of DMA. The high-frequency and high-accuracy measured night flow data were analyzed, which indicated that the night flow data of DMA at different time periods are in normal distribution and the lowest night flow data is close to the real loss of DMA. In this study, the minimum night flow data from 2 AM to 4 AM in the early morning were analyzed based on the confidence level of 95.5% and confidence interval of (m-2d, m+2d).. The results showed that the minimum night flow of DMA after removing the abnormal values characterized by m-2dcan eliminate the effects of error and interference of measured data, and therefore obtain the real loss of DMA. This method can lower the evaluation error of night water demand, and facilitate the in-situ meter flow measurement to assess the DMA leakage level quickly.
The analysis of the night minimum flow data in the Districted Metered Area (DMA) of the water distribution system can characterize the real loss of DMA. The high-frequency and high-accuracy measured night flow data were analyzed, which indicated that the night flow data of DMA at different time periods are in normal distribution and the lowest night flow data is close to the real loss of DMA. In this study, the minimum night flow data from 2 AM to 4 AM in the early morning were analyzed based on the confidence level of 95.5% and confidence interval of (m-2d, m+2d).. The results showed that the minimum night flow of DMA after removing the abnormal values characterized by m-2dcan eliminate the effects of error and interference of measured data, and therefore obtain the real loss of DMA. This method can lower the evaluation error of night water demand, and facilitate the in-situ meter flow measurement to assess the DMA leakage level quickly.
Abstract:
Based on the daily data of precipitation and temperature of 30 basic meteorological stations during the period 1956-2010, twelve indices characterizing extreme climate change have been selected to analyze the temporal changes in precipitation and temperature extremes in the Hai River Basin. As per many other parts of the world, the analysis shows an increase in the intensity, frequency and duration of high temperature extremes and a decrease in that of cold extremes. The intensity of short-time precipitation extremes shows an increase and the frequency of heavy precipitation shows a decrease. The consecutive wet days shows a decrease, while the consecutive dry days shows an increase in recent decades, thus the dry pattern has been aggravated in the basin. The annual high temperature extremes and short-time precipitation extremes have begun to frequently occur since 1990s from interdecadal variations, the rainfall of long-duration precipitation events has shown a decrease however. The general warm and dry trend and precipitation concentration will have a negative impact on the agriculture production and water resources development. Meanwhile, the increase of short-time precipitation extremes may exacerbate the risk of local flood disaster in mountainous area as well as urban waterlogging.
Based on the daily data of precipitation and temperature of 30 basic meteorological stations during the period 1956-2010, twelve indices characterizing extreme climate change have been selected to analyze the temporal changes in precipitation and temperature extremes in the Hai River Basin. As per many other parts of the world, the analysis shows an increase in the intensity, frequency and duration of high temperature extremes and a decrease in that of cold extremes. The intensity of short-time precipitation extremes shows an increase and the frequency of heavy precipitation shows a decrease. The consecutive wet days shows a decrease, while the consecutive dry days shows an increase in recent decades, thus the dry pattern has been aggravated in the basin. The annual high temperature extremes and short-time precipitation extremes have begun to frequently occur since 1990s from interdecadal variations, the rainfall of long-duration precipitation events has shown a decrease however. The general warm and dry trend and precipitation concentration will have a negative impact on the agriculture production and water resources development. Meanwhile, the increase of short-time precipitation extremes may exacerbate the risk of local flood disaster in mountainous area as well as urban waterlogging.
Abstract:
Compared with the traditional determined hydrologic forecast, hydrologic ensemble forecast contains various uncertainties in the hydrologic forecast processes. Therefore, the accuracy and validity of hydrologic forecast have been improved theoretically. Meanwhile, the cognitive and predictive capabilities of the events such as storm, flood, and drought have been enhanced in the practical applications. The hydrologic ensemble forecast can provide more accurate and useful information in flood control, drought relief, and sustainable water resources management. In this paper, we firstly reviewed the history of hydrologic ensemble forecast, and then we summarized the research progresses in theory, methods, as well as the applications and operational hydrologic ensemble forecast. We focused on two research aspects of the pre-processing and post-processing issues in an effort to provide a useful platform for the development of hydrologic ensemble prediction. The perspectives and recommendations on this subject were provided. This paper is of important significance in the future development of hydrologic ensemble forecast research.
Compared with the traditional determined hydrologic forecast, hydrologic ensemble forecast contains various uncertainties in the hydrologic forecast processes. Therefore, the accuracy and validity of hydrologic forecast have been improved theoretically. Meanwhile, the cognitive and predictive capabilities of the events such as storm, flood, and drought have been enhanced in the practical applications. The hydrologic ensemble forecast can provide more accurate and useful information in flood control, drought relief, and sustainable water resources management. In this paper, we firstly reviewed the history of hydrologic ensemble forecast, and then we summarized the research progresses in theory, methods, as well as the applications and operational hydrologic ensemble forecast. We focused on two research aspects of the pre-processing and post-processing issues in an effort to provide a useful platform for the development of hydrologic ensemble prediction. The perspectives and recommendations on this subject were provided. This paper is of important significance in the future development of hydrologic ensemble forecast research.
Abstract:
As a quantitative indicator of drought, drought index plays an important role in the monitoring and forecasting of drought and water resources management, and it is also a useful research tool in the field of hydrology and water resources. Over the last decade, the primary progress in the development and improvement of drought index involved the introduction of evapotranspiration as a factor of the index calculation, which can improve the parameter accuracy in model simulation and combine with the model algorithm of hydrological process. The application of drought index included the inversion and prediction of regional drought, crop yield prediction, forest fire detection, and paleoclimate reconstruction. The development and application of drought index provided an effective tool for regional drought monitoring and water resources management; however, the quantification and comprehensive evaluation of drought index should be considered as research priorities, which can help improve the accuracy and reliability of model monitoring and thus provide new options and technical approaches for rapid monitoring of drought.
As a quantitative indicator of drought, drought index plays an important role in the monitoring and forecasting of drought and water resources management, and it is also a useful research tool in the field of hydrology and water resources. Over the last decade, the primary progress in the development and improvement of drought index involved the introduction of evapotranspiration as a factor of the index calculation, which can improve the parameter accuracy in model simulation and combine with the model algorithm of hydrological process. The application of drought index included the inversion and prediction of regional drought, crop yield prediction, forest fire detection, and paleoclimate reconstruction. The development and application of drought index provided an effective tool for regional drought monitoring and water resources management; however, the quantification and comprehensive evaluation of drought index should be considered as research priorities, which can help improve the accuracy and reliability of model monitoring and thus provide new options and technical approaches for rapid monitoring of drought.
Abstract:
With the r apid development o f meso scale numer ical at mospher ic model WRF in r ecent y ears, its application is wider and w ider. In or der to ex plain the mechanism, r eveal the develo pment directio n and pr ov ide refer ence for r elated fields research2 er s, WRF model sy stem is int roduced, it is discussed that the influence o f parameterized phy sical pr ocesses, data assimilatio n and reasonable spat ial scale o n the simulation effect o f WRF model. Related studies have shown that: ( 1) differ ent par ameter2 ized phy sical processes need to be chosen in different reg ion and different time; ( 2) the common data assimilation method is 3DVar data assimilatio n at present, hybr id data assimilatio n may be a better met ho d to impr ove the simulatio n effect of WRF model; ( 3) reasonable spat ial scales need to be cho sen because not the hig her hor izo nt al reso lution, t he better simulat ion effect for a ll research; ( 4) WRF mo del has g oo d simulat ion effect , hig h pr ediction accuracy , there is mo re w ide applicat ion.
With the r apid development o f meso scale numer ical at mospher ic model WRF in r ecent y ears, its application is wider and w ider. In or der to ex plain the mechanism, r eveal the develo pment directio n and pr ov ide refer ence for r elated fields research2 er s, WRF model sy stem is int roduced, it is discussed that the influence o f parameterized phy sical pr ocesses, data assimilatio n and reasonable spat ial scale o n the simulation effect o f WRF model. Related studies have shown that: ( 1) differ ent par ameter2 ized phy sical processes need to be chosen in different reg ion and different time; ( 2) the common data assimilation method is 3DVar data assimilatio n at present, hybr id data assimilatio n may be a better met ho d to impr ove the simulatio n effect of WRF model; ( 3) reasonable spat ial scales need to be cho sen because not the hig her hor izo nt al reso lution, t he better simulat ion effect for a ll research; ( 4) WRF mo del has g oo d simulat ion effect , hig h pr ediction accuracy , there is mo re w ide applicat ion.
Abstract:
The instantaneous peak flow (IPF) is the basic information for hydraulic design，construction and management. It also has an important influence on the investment and safety of hydraulic structures. However, the IPF records in Tibet are generally short in length, while mean daily flow (MDF) records are relatively longer. In this study, the IPF records are extended by analyzing the relationship between corresponding IPF and MDF records. The results show that the ratio between IPF and MDF is stable in most of hydrological stations. The relative error between estimated IPF and observed IPF is less than 10%. The results of flood frequency analysis using extended IPF series are more reasonable than that using the measured IPF series. For the stations with limited measured MDF, the HIMS model is used to extend the available MDF. The HIMS model is applied in three representative rivers of Tibet: the Nianchu river, Lhasa river and Niang river. The results show that the model has a good performance in both daily and peak flow simulation. The end year of IPF series in the three representative hydrological stations has been extended from 2000 to 2010 by the simulation results of HIMS and the relationship between IPF and MDF.
The instantaneous peak flow (IPF) is the basic information for hydraulic design，construction and management. It also has an important influence on the investment and safety of hydraulic structures. However, the IPF records in Tibet are generally short in length, while mean daily flow (MDF) records are relatively longer. In this study, the IPF records are extended by analyzing the relationship between corresponding IPF and MDF records. The results show that the ratio between IPF and MDF is stable in most of hydrological stations. The relative error between estimated IPF and observed IPF is less than 10%. The results of flood frequency analysis using extended IPF series are more reasonable than that using the measured IPF series. For the stations with limited measured MDF, the HIMS model is used to extend the available MDF. The HIMS model is applied in three representative rivers of Tibet: the Nianchu river, Lhasa river and Niang river. The results show that the model has a good performance in both daily and peak flow simulation. The end year of IPF series in the three representative hydrological stations has been extended from 2000 to 2010 by the simulation results of HIMS and the relationship between IPF and MDF.
Abstract:
The objective of this study is to evaluate the applicability of SWAT model to agricultural drought evaluation for regions without or lack of soil moisture data. For this purpose, the SWAT model was applied to simulate the hydrological process in the Bahe watershed of the upper Weihe River. The soil water content was obtained and it was used to calculate the relative soil moisture. The calculated relative soil moisture was regarded as the evaluation index of agricultural drought. The results showed that severe spring droughts occurred in 2001 and 2002 and summer drought occurred in 2003 in the Bahe watershed, which was in accordance with the actual conditions. . Therefore, SWAT model is applicable to agricultural drought evaluation for the area lack of soil moisture data.
The objective of this study is to evaluate the applicability of SWAT model to agricultural drought evaluation for regions without or lack of soil moisture data. For this purpose, the SWAT model was applied to simulate the hydrological process in the Bahe watershed of the upper Weihe River. The soil water content was obtained and it was used to calculate the relative soil moisture. The calculated relative soil moisture was regarded as the evaluation index of agricultural drought. The results showed that severe spring droughts occurred in 2001 and 2002 and summer drought occurred in 2003 in the Bahe watershed, which was in accordance with the actual conditions. . Therefore, SWAT model is applicable to agricultural drought evaluation for the area lack of soil moisture data.
Abstract:
Static cone penetration test (CPT) as is an in situ test, which is was widely used in the engineering practice. Based on recently research results, thise paper systematically introduced sums up the research and development course in of CPT and summarized the research progress of the, such as instrument development, cone resistance theoretical research of cone resistance, model test, numerical simulation, and engineering application of CPT. Empirical formula of to calculate the soil parameters using CPT on for different industries and different areas were summarized. The paper pointed out that iIt is necessary to fully consider the engineering characteristics of regional soil when using in application of the CPT results. Moreover, It should be point out that the theoretical analysis of excess pore water pressure, analytic solution of cylindrical hole space problem, and numerical analysis simulation for large deformation analysis theory need to be further improved..
Static cone penetration test (CPT) as is an in situ test, which is was widely used in the engineering practice. Based on recently research results, thise paper systematically introduced sums up the research and development course in of CPT and summarized the research progress of the, such as instrument development, cone resistance theoretical research of cone resistance, model test, numerical simulation, and engineering application of CPT. Empirical formula of to calculate the soil parameters using CPT on for different industries and different areas were summarized. The paper pointed out that iIt is necessary to fully consider the engineering characteristics of regional soil when using in application of the CPT results. Moreover, It should be point out that the theoretical analysis of excess pore water pressure, analytic solution of cylindrical hole space problem, and numerical analysis simulation for large deformation analysis theory need to be further improved..
Abstract:
Wetlands and aAtmosphere constantly engaged in the exchange of energy and material constantly, that is , free water surface of wetland and dense vegetation was are in the process of evapotranspirationthrough evapo-transpiration to enter into the atmosphere and a part of water returns to the groundwater as precipitation, thereby increasing the so that water vapour injected into the atmosphere， then formed the rain and returned to the ground, thereby it improved local humidity and precipitation. In this paper, Based on the precipitation data from 1974～2010 of Hengshui Lake and twenty- four24 nearby rRainfall sStations from 1974 to 2010 were used to calculate of periphery ， this article figured out the average precipitation of the Hengshui Lake District ，10- km radius affected zone, 10～2010- to 20- km circular affected zone， and 20- to～30- km circular affected zone. It analyzed theThe effects of the wetland of Hengshui Lake on precipitation were analyzed, and the main reasons were investigated based on the change regularity of different affected zone of Hengshui Lake wetland, and explore the main reason through precipitation formation mechanism of precipitation. The result showsed: that the precipitation decreases Hengshui Lake wetland from the near to the distant distance of the Hengshui Lake Wetland, indicating was obviously decreasing, it revealed that Hengshui Lake wetland has an adjustment function the adjustment effects of the wetland onto the climate of surrounding regional climatearea.
Wetlands and aAtmosphere constantly engaged in the exchange of energy and material constantly, that is , free water surface of wetland and dense vegetation was are in the process of evapotranspirationthrough evapo-transpiration to enter into the atmosphere and a part of water returns to the groundwater as precipitation, thereby increasing the so that water vapour injected into the atmosphere， then formed the rain and returned to the ground, thereby it improved local humidity and precipitation. In this paper, Based on the precipitation data from 1974～2010 of Hengshui Lake and twenty- four24 nearby rRainfall sStations from 1974 to 2010 were used to calculate of periphery ， this article figured out the average precipitation of the Hengshui Lake District ，10- km radius affected zone, 10～2010- to 20- km circular affected zone， and 20- to～30- km circular affected zone. It analyzed theThe effects of the wetland of Hengshui Lake on precipitation were analyzed, and the main reasons were investigated based on the change regularity of different affected zone of Hengshui Lake wetland, and explore the main reason through precipitation formation mechanism of precipitation. The result showsed: that the precipitation decreases Hengshui Lake wetland from the near to the distant distance of the Hengshui Lake Wetland, indicating was obviously decreasing, it revealed that Hengshui Lake wetland has an adjustment function the adjustment effects of the wetland onto the climate of surrounding regional climatearea.
Abstract:
Based on the monthly precipitation data of 25 meteorological stations in the Haihe River Basin from 1960 to 2010, the inter 2annual precipitation characteristics in the Haihe River Basin were analyzed using the linear regression and cumulative a 2 nomaly curve methods. T he probability distribution of precipitation was analyzed using the Pearson III curve method, and the spatial variation of precipitation was analyzed using the spatial interpolation method. T he results showed that (1) precipitation in the Haihe River Basin has a slightly decreasing trend in recent 51 years, and the decreasing trend is stable recently; ( 2) there is a trend with more wet years while less dry years in the Haihe River Basin and the trend is increasing; (3) seasonal variation of precipitation is obvious; and (4) precipitation decreases trend from the south to the north.
Based on the monthly precipitation data of 25 meteorological stations in the Haihe River Basin from 1960 to 2010, the inter 2annual precipitation characteristics in the Haihe River Basin were analyzed using the linear regression and cumulative a 2 nomaly curve methods. T he probability distribution of precipitation was analyzed using the Pearson III curve method, and the spatial variation of precipitation was analyzed using the spatial interpolation method. T he results showed that (1) precipitation in the Haihe River Basin has a slightly decreasing trend in recent 51 years, and the decreasing trend is stable recently; ( 2) there is a trend with more wet years while less dry years in the Haihe River Basin and the trend is increasing; (3) seasonal variation of precipitation is obvious; and (4) precipitation decreases trend from the south to the north.
Abstract:
A proposed water transfer tunnel will be excavated with tunnel boring machine (TBM) in the surrounding type-III rock. The shotcrete and reinforced concrete segment serve as the initial support and permanent liner, respectively. The considerable internal and external water pressures are loaded on the liner, with the water head values of 110 m and 200 m, respectively. In this paper, in consideration of the contact relationship between segments, the contact relationship between segment and surrounding structure, and the cooperative working performance of reinforcement bars and concrete, the stress deformation characteristics of the liner under high water pressures are analyzed using the finite element method. The results showed that the external water pressure is the decisive load for the design of tunnel liner, and therefore a simplified model of segment liner design was proposed. The results suggested that it is feasible to use the reinforced concrete segment as tunnel lining under the conditions of the surrounding rock, support, and water pressure shown in the study.
A proposed water transfer tunnel will be excavated with tunnel boring machine (TBM) in the surrounding type-III rock. The shotcrete and reinforced concrete segment serve as the initial support and permanent liner, respectively. The considerable internal and external water pressures are loaded on the liner, with the water head values of 110 m and 200 m, respectively. In this paper, in consideration of the contact relationship between segments, the contact relationship between segment and surrounding structure, and the cooperative working performance of reinforcement bars and concrete, the stress deformation characteristics of the liner under high water pressures are analyzed using the finite element method. The results showed that the external water pressure is the decisive load for the design of tunnel liner, and therefore a simplified model of segment liner design was proposed. The results suggested that it is feasible to use the reinforced concrete segment as tunnel lining under the conditions of the surrounding rock, support, and water pressure shown in the study.
Abstract:
The impacts of human activities and dry climate aggravate the water pollution and eutrophication in the Baiyang Lake. Through the analysis of hydro 2chemical compositions of the water, five indexes[Chla, TN, T P, COD Mn, and SD] , which are re 2 lated to water eutrophication, are selected as evaluation parameters, and the comprehensive nutrition index method is adopted to determine the water eutrophication type. T he results of water quality monitoring data show that the type of water is CNaII, and the lake is in mesotrophic or eutrophic state determined by the comprehensive nutrition index method. The principal component analysis results show that TP is the main factor to cause water pollution in the lake. According to the analysis of diatom and its combination, the diatom in the lake is characterized by the combination of eutrophic species Cyclotellameneghiniana ( 20. 43%) and Cyclostep hanos tholif ormis ( 25. 40%) , which indicates that the lake is in the eutrophication state and water environment is in danger.
The impacts of human activities and dry climate aggravate the water pollution and eutrophication in the Baiyang Lake. Through the analysis of hydro 2chemical compositions of the water, five indexes[Chla, TN, T P, COD Mn, and SD] , which are re 2 lated to water eutrophication, are selected as evaluation parameters, and the comprehensive nutrition index method is adopted to determine the water eutrophication type. T he results of water quality monitoring data show that the type of water is CNaII, and the lake is in mesotrophic or eutrophic state determined by the comprehensive nutrition index method. The principal component analysis results show that TP is the main factor to cause water pollution in the lake. According to the analysis of diatom and its combination, the diatom in the lake is characterized by the combination of eutrophic species Cyclotellameneghiniana ( 20. 43%) and Cyclostep hanos tholif ormis ( 25. 40%) , which indicates that the lake is in the eutrophication state and water environment is in danger.
Abstract:
Thro ug h the analysis of t he technique, envir onment, law , and eco nomy in the manag ement and operatio n o f inter2basin water transfer projects abro ad, this paper summar ized the successful ex per ience o f int er2basin w ater tr ansfer pr ojects in the wo rld fr om the aspects of leg islat ion, w ater r ig ht s, water pr ice, unified manag ement o f water resources, investment manag ement of eng ineering const ruct ion, and management o per ation mode, w hich can pro vide t he refer ence fo r the o per ation of inter2basin water transfer pro jects in China.
Thro ug h the analysis of t he technique, envir onment, law , and eco nomy in the manag ement and operatio n o f inter2basin water transfer projects abro ad, this paper summar ized the successful ex per ience o f int er2basin w ater tr ansfer pr ojects in the wo rld fr om the aspects of leg islat ion, w ater r ig ht s, water pr ice, unified manag ement o f water resources, investment manag ement of eng ineering const ruct ion, and management o per ation mode, w hich can pro vide t he refer ence fo r the o per ation of inter2basin water transfer pro jects in China.
Periodical information
Competent Authority:Department of Water Resources of Hebei Procince
Sponsored by:Hebei Institute of Water Resources
Chief Editor :ZHANG Shuantang
Edited and Published by:The Editorial Dept South-to-North Water Transfers and Water Science &Technology
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