Volume 15,Issue 1,2017 Table of Contents
2017, 15(1):1-6.
Abstract:
With the purpose of exploring the features of hydrological responses to climate change and human activities, a quantitative assessment of the relative contributions from climate variability and human activities to runoff changes in the Upper Hanjiang River basin was conducted using two methods, namely the elasticity method and the hydrological modeling method. The results showed that annual runoff underwent a significant decreasing trend over the period of 1961-2013, and a breaking point was detected in 1985. Precipitation and potential evapotranspiration both decreased gradually over the same period, but the trends were not significant. Climate variability accounted for 42.8%-43.5% of the decrease in runoff, and the impact of human activities accounted for 56.5%-57.2%, showing a more important influence on runoff changes. Moreover, the latter’s influence was in an increasing trend.
With the purpose of exploring the features of hydrological responses to climate change and human activities, a quantitative assessment of the relative contributions from climate variability and human activities to runoff changes in the Upper Hanjiang River basin was conducted using two methods, namely the elasticity method and the hydrological modeling method. The results showed that annual runoff underwent a significant decreasing trend over the period of 1961-2013, and a breaking point was detected in 1985. Precipitation and potential evapotranspiration both decreased gradually over the same period, but the trends were not significant. Climate variability accounted for 42.8%-43.5% of the decrease in runoff, and the impact of human activities accounted for 56.5%-57.2%, showing a more important influence on runoff changes. Moreover, the latter’s influence was in an increasing trend.
2017, 15(1):7-13.
Abstract:
Water resources shortage is an important factor restricting the economic and social development of the city. Rational allocation and effective use of limited water resources is an effective way to solve the contradiction between water supply and demand. Xuchang City is taking as an example for national water ecological civilization city construction in this paper. The water demand is forecasted by the quota method according to the analysis of the status of water resources development and utilization. Based on the multi-year average water resources, 2011 is taking as the research base year. According to the water resources access, engineering scheme and various water demands, etc. MIKE BASIN is used to establish the water resources allocation model. The water supply and demand balance is simulated in Xuchang City. The water supply and demand allocation is obtained in different planning levels through three times of supply and demand balance analysis program, and ultimately to achieve water supply and demand balance, so that the limited water resources can maximize efficiency. The research results show that the local water resources can be combined with the multi-mode joint operation of South-to-North water diversion, Yellow River water diversion and reclaimed water reclamation to meet the water demand of Xuchang City in the medium-long term sustainable economic and social development. It also has significance guide for the future sustainable utilization of water resources in Xuchang City.
Water resources shortage is an important factor restricting the economic and social development of the city. Rational allocation and effective use of limited water resources is an effective way to solve the contradiction between water supply and demand. Xuchang City is taking as an example for national water ecological civilization city construction in this paper. The water demand is forecasted by the quota method according to the analysis of the status of water resources development and utilization. Based on the multi-year average water resources, 2011 is taking as the research base year. According to the water resources access, engineering scheme and various water demands, etc. MIKE BASIN is used to establish the water resources allocation model. The water supply and demand balance is simulated in Xuchang City. The water supply and demand allocation is obtained in different planning levels through three times of supply and demand balance analysis program, and ultimately to achieve water supply and demand balance, so that the limited water resources can maximize efficiency. The research results show that the local water resources can be combined with the multi-mode joint operation of South-to-North water diversion, Yellow River water diversion and reclaimed water reclamation to meet the water demand of Xuchang City in the medium-long term sustainable economic and social development. It also has significance guide for the future sustainable utilization of water resources in Xuchang City.
2017, 15(1):14-17.
Abstract:
Generally, moisture and efficiency factor maximization or moisture and wind maximization are two approaches used to estimate the probable maximum precipitation (PMP) in China. But only the value obtained from the moisture and efficiency factor maximization is used as the PMP estimation in most cases, because the moisture and wind maximization approach regularly overestimates and therefore is usually taken as reference only. This paper presents a modified moisture and wind maximization method based on the “Wind Rose Diagram” applied in port engineering. First, measured wind speed and direction data are grouped according to the direction of prevailing wind in the studied area. Then, the high-efficiency storm in each group of wind direction is maximized. Finally, the maximum value among all groups is chosen to be the final result of moisture and wind maximization, that is PMP value. The new approach was tested on the Xianning nuclear power plant in Hubei Province, and generated a more reasonable PMP value compared with the traditional approaches.
Generally, moisture and efficiency factor maximization or moisture and wind maximization are two approaches used to estimate the probable maximum precipitation (PMP) in China. But only the value obtained from the moisture and efficiency factor maximization is used as the PMP estimation in most cases, because the moisture and wind maximization approach regularly overestimates and therefore is usually taken as reference only. This paper presents a modified moisture and wind maximization method based on the “Wind Rose Diagram” applied in port engineering. First, measured wind speed and direction data are grouped according to the direction of prevailing wind in the studied area. Then, the high-efficiency storm in each group of wind direction is maximized. Finally, the maximum value among all groups is chosen to be the final result of moisture and wind maximization, that is PMP value. The new approach was tested on the Xianning nuclear power plant in Hubei Province, and generated a more reasonable PMP value compared with the traditional approaches.
2017, 15(1):18-24.
Abstract:
Water system is constantly changing under the influences of climate changes and human activities so that the development and utilization of water resources should be adapted to these changes rather than conform to a fixed control threshold or certain constraints. Therefore, studying the adaptive utilization and management of water resources is of great significance. In this paper, the principle and mode of adaptive utilization of water resources (AUWR) is expounded based on the analysis of water system and its relationship with environmental changes. Based on the understanding of the mechanism of AUWR under environmental changes, the theory of adaptive utilization of water resources (AUWR theory) is put forward, a framework system of the theory is constructed, and its basic concepts and key contents are expounded. Based on the analysis of modern water management practices in China, this paper elaborates on the underlying AUWR theory, and the existing problems in modern water management practices in China as well as the possible solutions to these problems using the AUWR theory. The study shows that the AUWR theory can provide significant guidance on the rational development, comprehensive utilization, and scientific management of water resources, as well as lay the theoretical foundation for the research and practice of water resources utilization under environmental changes.
Water system is constantly changing under the influences of climate changes and human activities so that the development and utilization of water resources should be adapted to these changes rather than conform to a fixed control threshold or certain constraints. Therefore, studying the adaptive utilization and management of water resources is of great significance. In this paper, the principle and mode of adaptive utilization of water resources (AUWR) is expounded based on the analysis of water system and its relationship with environmental changes. Based on the understanding of the mechanism of AUWR under environmental changes, the theory of adaptive utilization of water resources (AUWR theory) is put forward, a framework system of the theory is constructed, and its basic concepts and key contents are expounded. Based on the analysis of modern water management practices in China, this paper elaborates on the underlying AUWR theory, and the existing problems in modern water management practices in China as well as the possible solutions to these problems using the AUWR theory. The study shows that the AUWR theory can provide significant guidance on the rational development, comprehensive utilization, and scientific management of water resources, as well as lay the theoretical foundation for the research and practice of water resources utilization under environmental changes.
2017, 15(1):25-32.
Abstract:
Traditional methods can only describe the average case of ET0 temporal and spatial distribution, but it is difficult for their degree of dispersion and stability were quantified. According to the meteorological data and geographic information of 5 stations in Anhui Huaibei Plain, using Penman-Monteith to calculate ET0, its temporal and spatial distribution characteristics was analyzed based on cloud model. The results showed that: Inter-annual ET0 was provided with a decrease tendency, ET0 in spring and winter were provided with a growing tendency, and in summer and autumn with a decrease trend; inter-annual ET0 was more uniform in spatial distribution and seasonal ET0 uneven; ET0 was more fragmented and unstable in 2004, and relatively concentrated and stable in 1956; ET0 was more fragmented and unstable in Fuyang station, and relatively concentrated and stable in Suxian station; the degree of dispersion of ET0 in temporal variation was smaller than in spatial distribution, and stability was similar. Therefore, analysis on characteristics of ET0 in temporal-spatial distribution in Huaibei Plain based on cloud model is feasible and effective, and the characteristics of ET0 in temporal-spatial distribution can be analyzed visually. The research results can provide scientific reference for evapotranspiration of various crop as well as drought and irrigation research.
Traditional methods can only describe the average case of ET0 temporal and spatial distribution, but it is difficult for their degree of dispersion and stability were quantified. According to the meteorological data and geographic information of 5 stations in Anhui Huaibei Plain, using Penman-Monteith to calculate ET0, its temporal and spatial distribution characteristics was analyzed based on cloud model. The results showed that: Inter-annual ET0 was provided with a decrease tendency, ET0 in spring and winter were provided with a growing tendency, and in summer and autumn with a decrease trend; inter-annual ET0 was more uniform in spatial distribution and seasonal ET0 uneven; ET0 was more fragmented and unstable in 2004, and relatively concentrated and stable in 1956; ET0 was more fragmented and unstable in Fuyang station, and relatively concentrated and stable in Suxian station; the degree of dispersion of ET0 in temporal variation was smaller than in spatial distribution, and stability was similar. Therefore, analysis on characteristics of ET0 in temporal-spatial distribution in Huaibei Plain based on cloud model is feasible and effective, and the characteristics of ET0 in temporal-spatial distribution can be analyzed visually. The research results can provide scientific reference for evapotranspiration of various crop as well as drought and irrigation research.
2017, 15(1):33-38.
Abstract:
With the implementation of non-engineering measures on flood monitoring and early warning and the nationwide flood disaster prevention construction from 2013 to 2015, the comprehensive ability of the entire Ningxia region in flood control and disaster reduction has significantly improved. But, currently there is no early warning index for scientific, systematic and quantitative analysis of flood disasters such as rainstorm, flood, water logging, landslides, and mudslides, making it difficult to conduct emergency disaster relief, emergency response and emergency rescue in sudden flood disasters. In light of the actual river distribution and flood control project construction in Ningxia, based on the existing methods of ascertaining critical rainfall, we used the rainstorm isoline and P-III frequency curve table to estimate the rainfall value corresponding to different flood magnitudes, and used the value as the early warning value for flood disasters. This method is simple and easy to operate. The calculation results have important significance to flood prevention and disaster reduction in Ningxia.
With the implementation of non-engineering measures on flood monitoring and early warning and the nationwide flood disaster prevention construction from 2013 to 2015, the comprehensive ability of the entire Ningxia region in flood control and disaster reduction has significantly improved. But, currently there is no early warning index for scientific, systematic and quantitative analysis of flood disasters such as rainstorm, flood, water logging, landslides, and mudslides, making it difficult to conduct emergency disaster relief, emergency response and emergency rescue in sudden flood disasters. In light of the actual river distribution and flood control project construction in Ningxia, based on the existing methods of ascertaining critical rainfall, we used the rainstorm isoline and P-III frequency curve table to estimate the rainfall value corresponding to different flood magnitudes, and used the value as the early warning value for flood disasters. This method is simple and easy to operate. The calculation results have important significance to flood prevention and disaster reduction in Ningxia.
2017, 15(1):39-42.
Abstract:
Climate change and intense human activities have an important impact on hydrological cycle and its spatial and temporal evolution. The previous research results can no longer truly reflect the hydrological changes in modern circumstances. As the representative of conceptual models, the Xin'an river model is no longer suitable for the simulation of the comprehensive hydrological elements in the basin, so a lot of basic research work needs to be strengthened. To solve this problem, this paper takes the water resources experiment station of Xin'an river as an example, and expounds the application of the basin-nested enhanced observation scheme in practice. Based on the original facilities, an integrated observation field for prototype basin and slope land hydrology, a nested enhanced observation basin, a center for comprehensive hydrological experiment, analysis and testing, and a remote receiving center will be newly nested. Results show that the scheme can effectively increase data resource types and expand coverage, provide data for both the development of a new-generation hydrologic model system and the construction of an atmospheric-hydrological-ecological integrated model.
Climate change and intense human activities have an important impact on hydrological cycle and its spatial and temporal evolution. The previous research results can no longer truly reflect the hydrological changes in modern circumstances. As the representative of conceptual models, the Xin'an river model is no longer suitable for the simulation of the comprehensive hydrological elements in the basin, so a lot of basic research work needs to be strengthened. To solve this problem, this paper takes the water resources experiment station of Xin'an river as an example, and expounds the application of the basin-nested enhanced observation scheme in practice. Based on the original facilities, an integrated observation field for prototype basin and slope land hydrology, a nested enhanced observation basin, a center for comprehensive hydrological experiment, analysis and testing, and a remote receiving center will be newly nested. Results show that the scheme can effectively increase data resource types and expand coverage, provide data for both the development of a new-generation hydrologic model system and the construction of an atmospheric-hydrological-ecological integrated model.
2017, 15(1):43-48.
Abstract:
Hydrological forecast is very important for flood control, drought resistance and water resources regulation. It is usually based on model simulation. Each hydrological model has its own characteristics and feasible basin. Multi-model hydrological forecast is one of the effective methods to reduce the forecasting uncertainty. This paper chose three commonly used hydrological models: time-variant gain hydrological model, Xin’anjiang model, and Sacramento model. The case study was on Feilaixia basin of Pearl River. The three hydrological models were used for independent simulation with the same input and initial value. Then, BMA and SMA were run on the three models’ results. The research results show that the BMA results are better than the results from single model simulation.
Hydrological forecast is very important for flood control, drought resistance and water resources regulation. It is usually based on model simulation. Each hydrological model has its own characteristics and feasible basin. Multi-model hydrological forecast is one of the effective methods to reduce the forecasting uncertainty. This paper chose three commonly used hydrological models: time-variant gain hydrological model, Xin’anjiang model, and Sacramento model. The case study was on Feilaixia basin of Pearl River. The three hydrological models were used for independent simulation with the same input and initial value. Then, BMA and SMA were run on the three models’ results. The research results show that the BMA results are better than the results from single model simulation.
2017, 15(1):49-54.
Abstract:
Based on the basic data of 1971-2010 at 14 meteorological stations in northwestern Liaoning province, this paper selected four indexes (the precipitation anomaly, number of consecutive days without rain, river runoff anomaly, and relative humidity), and obtained the comprehensive drought level characteristic value of northwestern Liaoning province using the variable fuzzy evaluation method. Then it used the linear trend estimation method and Mann-Kendall test method to analyze the trend of drought and used the IDW method to analyze the spatial variation characteristics of comprehensive drought. The results show that the drought is growing significantly more serious. During 1971-1980, the drought was mostly mild, but was aggravated after the 1980s, and became the most serious during 1981-1990. The period of 1980-2010 witnessed a high incidence of severe droughts but few extremely severe droughts. The drought was more serious and was aggravated with time in the northeast and southwest of northwestern Liaoning province, but was less serious in the central region. Therefore, drought resistance and disaster reduction efforts should be mainly concentrated on the northeast and southwest of the region.
Based on the basic data of 1971-2010 at 14 meteorological stations in northwestern Liaoning province, this paper selected four indexes (the precipitation anomaly, number of consecutive days without rain, river runoff anomaly, and relative humidity), and obtained the comprehensive drought level characteristic value of northwestern Liaoning province using the variable fuzzy evaluation method. Then it used the linear trend estimation method and Mann-Kendall test method to analyze the trend of drought and used the IDW method to analyze the spatial variation characteristics of comprehensive drought. The results show that the drought is growing significantly more serious. During 1971-1980, the drought was mostly mild, but was aggravated after the 1980s, and became the most serious during 1981-1990. The period of 1980-2010 witnessed a high incidence of severe droughts but few extremely severe droughts. The drought was more serious and was aggravated with time in the northeast and southwest of northwestern Liaoning province, but was less serious in the central region. Therefore, drought resistance and disaster reduction efforts should be mainly concentrated on the northeast and southwest of the region.
2017, 15(1):55-59.
Abstract:
Chaotic theory is an important means of hydrology time series analysis. In order to get reliable analysis results, it is recommended to make a full use of time series. But the research about how the length of time series affects the identification of chaotic characteristics is rare. In this paper, we carried out a study about the responding effect of the maximum Lyapunov exponent to the length of time series with the use of daily runoff time series of gauged stations named Wulong and Beibei in Yangtze River. The result suggested that short daily runoff time series would affect the result of chaotic identification and make the result unreliable; besides, when the length of daily runoff time series reached 3000, the chaotic characteristics became stable and reliable, and it saved a lot of computing time at the same time.
Chaotic theory is an important means of hydrology time series analysis. In order to get reliable analysis results, it is recommended to make a full use of time series. But the research about how the length of time series affects the identification of chaotic characteristics is rare. In this paper, we carried out a study about the responding effect of the maximum Lyapunov exponent to the length of time series with the use of daily runoff time series of gauged stations named Wulong and Beibei in Yangtze River. The result suggested that short daily runoff time series would affect the result of chaotic identification and make the result unreliable; besides, when the length of daily runoff time series reached 3000, the chaotic characteristics became stable and reliable, and it saved a lot of computing time at the same time.
2017, 15(1):60-66.
Abstract:
The accuracy of mid- and long-term forecast on hydrological time series is highly questioned due to the non-stationary and nonlinear complex changes of the series. The "Decomposition - Prediction - Reconstruction" model, as a new and effective forecasting method, has captured the attention of many scholars in related fields in recent years. But troubled by large errors in high-frequency component prediction, uncertain trend and other issues, this model still requires a lot of improvements in the development process. Among all the improvements, reconstruction of runoff component is intensely crucial in controlling high-frequency component prediction error and improving prediction accuracy of the hydrological series. To do this, the "Decomposition - Prediction" hybrid model was established in this paper using empirical mode decomposition (EMD) and autoregressive model (AR). Two reconstruction methods were proposed based on the particle swarm optimization (PSO) algorithm, which were the PSO-based reconstruction coefficient optimization method and the high-frequency component removal & reconstruction coefficient optimization method. These two methods plus the previous high-frequency component removal method were used to compare the efficacy of hydrological forecasting in a case study on Dingjiagou station in northern Shaanxi, Huaxian station in middle Shaanxi and Baihe station in southern Shaanxi. The results showed that the high-frequency component removal method, PSO-based reconstruction coefficient optimization method and high-frequency component removal & reconstruction coefficient optimization method all predict better than the standard reconstruction method, as reflected by five error evaluation indicators. Thus it can be drawn that these three reconstruction methods can improve the prediction accuracy in different degrees. High-frequency component removal method emphasizes removing the high-frequency component, which is the most unstable and unpredictable, so as to enhance the prediction accuracy, but only by a limited margin due to the simple removal process. PSO-based reconstruction coefficient optimization method is to optimize the reconstruction coefficients of all runoff components and to reconstruct the forecasted series. It can reduce errors during components reconstruction to the greatest extent and improve the prediction accuracy effectively. High-frequency component removal & reconstruction coefficient optimization method combines the above two methods and predicts better than all the other methods.
The accuracy of mid- and long-term forecast on hydrological time series is highly questioned due to the non-stationary and nonlinear complex changes of the series. The "Decomposition - Prediction - Reconstruction" model, as a new and effective forecasting method, has captured the attention of many scholars in related fields in recent years. But troubled by large errors in high-frequency component prediction, uncertain trend and other issues, this model still requires a lot of improvements in the development process. Among all the improvements, reconstruction of runoff component is intensely crucial in controlling high-frequency component prediction error and improving prediction accuracy of the hydrological series. To do this, the "Decomposition - Prediction" hybrid model was established in this paper using empirical mode decomposition (EMD) and autoregressive model (AR). Two reconstruction methods were proposed based on the particle swarm optimization (PSO) algorithm, which were the PSO-based reconstruction coefficient optimization method and the high-frequency component removal & reconstruction coefficient optimization method. These two methods plus the previous high-frequency component removal method were used to compare the efficacy of hydrological forecasting in a case study on Dingjiagou station in northern Shaanxi, Huaxian station in middle Shaanxi and Baihe station in southern Shaanxi. The results showed that the high-frequency component removal method, PSO-based reconstruction coefficient optimization method and high-frequency component removal & reconstruction coefficient optimization method all predict better than the standard reconstruction method, as reflected by five error evaluation indicators. Thus it can be drawn that these three reconstruction methods can improve the prediction accuracy in different degrees. High-frequency component removal method emphasizes removing the high-frequency component, which is the most unstable and unpredictable, so as to enhance the prediction accuracy, but only by a limited margin due to the simple removal process. PSO-based reconstruction coefficient optimization method is to optimize the reconstruction coefficients of all runoff components and to reconstruct the forecasted series. It can reduce errors during components reconstruction to the greatest extent and improve the prediction accuracy effectively. High-frequency component removal & reconstruction coefficient optimization method combines the above two methods and predicts better than all the other methods.
12 Analysis of rational supply and demand of water resources in Turpan area in the coordination mode
2017, 15(1):67-71.
Abstract:
System dynamics is based on the system theory. It can incorporate the water use sub-system and water supply sub-system into the water resources supply and demand system, and can be used to analyze the influence of the factors in each subsystem on the overall system. The system dynamics software Stella can predict the development trend of water supply and demand through scenario simulation. Turpan water resources supply and demand system model was constructed using the system dynamics method based on the actual situation of Turpan social economic development and ecological water demand. Four different scenarios were set to simulate the variation trend of water resources supply and demand in Turpan area in 2013-2030. Then analysis was conducted on the balance of water resources supply and demand in the region. Research results showed that in order to achieve optimal use of water resources to ensure sustainable development of Turpan area, we must intensify water conservancy construction, increase investment in water conservancy, further implement water-saving measures, and use water resources smartly and reasonably.
System dynamics is based on the system theory. It can incorporate the water use sub-system and water supply sub-system into the water resources supply and demand system, and can be used to analyze the influence of the factors in each subsystem on the overall system. The system dynamics software Stella can predict the development trend of water supply and demand through scenario simulation. Turpan water resources supply and demand system model was constructed using the system dynamics method based on the actual situation of Turpan social economic development and ecological water demand. Four different scenarios were set to simulate the variation trend of water resources supply and demand in Turpan area in 2013-2030. Then analysis was conducted on the balance of water resources supply and demand in the region. Research results showed that in order to achieve optimal use of water resources to ensure sustainable development of Turpan area, we must intensify water conservancy construction, increase investment in water conservancy, further implement water-saving measures, and use water resources smartly and reasonably.
2017, 15(1):72-78.
Abstract:
In order to improve the accuracy of flood forecasting in basins with dramatic changes in the base course, this paper proposes a coupled hydrological-hydrodynamic flood forecasting model which couples the traditional hydrological model with the one-dimensional hydrodynamic model. First, the flow process of a section was obtained by the hydrological model and was used as the boundary condition of the one-dimensional hydrodynamic model. Then the one-dimensional hydrodynamic model was applied to simulate the flood routing in the river channel. The proposed method was tested on the Waijia River basin in Yantai City, China. The results indicate that the coupled model can simulate runoff yield with a high qualification rate, and generate flow processes that tally with the measured values. It can be concluded that this coupled hydrological-hydrodynamic model may make a significant contribution to flood forecasting in basins with complex hydrologic and hydraulic conditions thanks to its ability to model water movement in the basin.
In order to improve the accuracy of flood forecasting in basins with dramatic changes in the base course, this paper proposes a coupled hydrological-hydrodynamic flood forecasting model which couples the traditional hydrological model with the one-dimensional hydrodynamic model. First, the flow process of a section was obtained by the hydrological model and was used as the boundary condition of the one-dimensional hydrodynamic model. Then the one-dimensional hydrodynamic model was applied to simulate the flood routing in the river channel. The proposed method was tested on the Waijia River basin in Yantai City, China. The results indicate that the coupled model can simulate runoff yield with a high qualification rate, and generate flow processes that tally with the measured values. It can be concluded that this coupled hydrological-hydrodynamic model may make a significant contribution to flood forecasting in basins with complex hydrologic and hydraulic conditions thanks to its ability to model water movement in the basin.
2017, 15(1):79-87.
Abstract:
Lignin is one of the major components of terrestrial organic matter, as well as a good biomarker of terrestrial organic matter. The photodegradation of lignin in aquatic environments can significantly affect its indicative parameters. Firstly, this review introduced the structure of lignin and its application as a biomarker. Then, the mechanism and influencing factors of lignin photodegradation in aquatic environments were described and discussed. Meanwhile, the changes of lignin indicative parameters and other organic matter parameters (13C isotope, CDOM, et al.) caused by the photodegradation, as well as researches about lignin photodegradation in rivers, estuaries and offshore were summarized. Finally, some possible research fields of lignin photodegradation in water environment were pointed out, including the use of CDOM optical spectrum measurements to characterize the photodegradation of lignin, combining with other parameters to characterize the sources and strengthening the study of the interaction between photodegradation and biodegradation.
Lignin is one of the major components of terrestrial organic matter, as well as a good biomarker of terrestrial organic matter. The photodegradation of lignin in aquatic environments can significantly affect its indicative parameters. Firstly, this review introduced the structure of lignin and its application as a biomarker. Then, the mechanism and influencing factors of lignin photodegradation in aquatic environments were described and discussed. Meanwhile, the changes of lignin indicative parameters and other organic matter parameters (13C isotope, CDOM, et al.) caused by the photodegradation, as well as researches about lignin photodegradation in rivers, estuaries and offshore were summarized. Finally, some possible research fields of lignin photodegradation in water environment were pointed out, including the use of CDOM optical spectrum measurements to characterize the photodegradation of lignin, combining with other parameters to characterize the sources and strengthening the study of the interaction between photodegradation and biodegradation.
2017, 15(1):88-94.
Abstract:
The response of plant water use strategy to hydrological conditions is important for eco-hydrological research in arid areas. In the present paper, we studied a typical riparian plant, Populus euphratica, under different hydrological conditions in Ejina delta. We simultaneously collected samples of the plants’ xylem as well as the surrounding soil and extracted their water with a cryogenic vacuum extraction system. Meanwhile, we collected river water and groundwater samples. The δ18O of these samples were tested to analyze the relationship between potential water sources (river water, groundwater), soil water, and plant water by the isotopic mass balance model. The results indicated that the Populus euphratica that stands 75 m away from riverbank with a 2-m-deep water table mainly consumes water from the 1.0-2.0-m deep soil layer and 93.7% of the plant water is from the river. The Populus euphratica that stands 2 km away from riverbank with a 3.3-m-deep water table mainly absorbs soil water that is 1.4-3.2 m deep, and ultimately 80.0% of the plant water comes from groundwater (river water that stays long in the aquifer). It can be seen that the water use strategy of Populus euphratica varies significantly with their distance from riverbank and groundwater table depth.
The response of plant water use strategy to hydrological conditions is important for eco-hydrological research in arid areas. In the present paper, we studied a typical riparian plant, Populus euphratica, under different hydrological conditions in Ejina delta. We simultaneously collected samples of the plants’ xylem as well as the surrounding soil and extracted their water with a cryogenic vacuum extraction system. Meanwhile, we collected river water and groundwater samples. The δ18O of these samples were tested to analyze the relationship between potential water sources (river water, groundwater), soil water, and plant water by the isotopic mass balance model. The results indicated that the Populus euphratica that stands 75 m away from riverbank with a 2-m-deep water table mainly consumes water from the 1.0-2.0-m deep soil layer and 93.7% of the plant water is from the river. The Populus euphratica that stands 2 km away from riverbank with a 3.3-m-deep water table mainly absorbs soil water that is 1.4-3.2 m deep, and ultimately 80.0% of the plant water comes from groundwater (river water that stays long in the aquifer). It can be seen that the water use strategy of Populus euphratica varies significantly with their distance from riverbank and groundwater table depth.
2017, 15(1):95-101.
Abstract:
This article was aimed to establish an early warning system of tailings dam-break accidents, and provide guidance for emergency operation. The model of sand flow from tailings dam-break was used to simulate accident scenarios based on the characteristic of tailings dam-break. Combining simulation results with GIS tools, the process and impact of accidents were predicted and displayed spatially. The article used Laoguan River Basin, a tributary of the middle route of South to North Water Transfers, as a study case, and chose two typical tailing ponds from upstream and downstream to simulate accident scenario. The scale of the accident impact from upstream was 55 km, and the residential land in 3-5 km downstream of the tailing pond would be subjected to serious harm. The duration of accident impact was about 6-7 hours. The scale of the accident impact from downstream was 13 km, and the agricultural resources from downstream would be subjected to main harm. The duration of accident impact was about 2 hours. The simulation results have verified the practicability of the research and provided decision supports for emergency measures of tailings dam-break and daily safety management in this basin.
This article was aimed to establish an early warning system of tailings dam-break accidents, and provide guidance for emergency operation. The model of sand flow from tailings dam-break was used to simulate accident scenarios based on the characteristic of tailings dam-break. Combining simulation results with GIS tools, the process and impact of accidents were predicted and displayed spatially. The article used Laoguan River Basin, a tributary of the middle route of South to North Water Transfers, as a study case, and chose two typical tailing ponds from upstream and downstream to simulate accident scenario. The scale of the accident impact from upstream was 55 km, and the residential land in 3-5 km downstream of the tailing pond would be subjected to serious harm. The duration of accident impact was about 6-7 hours. The scale of the accident impact from downstream was 13 km, and the agricultural resources from downstream would be subjected to main harm. The duration of accident impact was about 2 hours. The simulation results have verified the practicability of the research and provided decision supports for emergency measures of tailings dam-break and daily safety management in this basin.
2017, 15(1):102-106.
Abstract:
Rigid revetment is widely used in traditional water conservancy and anti-schistosomiasis projects. It has a negative impact on the biological diversity of watercourses. A regular rigid revetment was designed for a water conservancy project based on the tidal data of a nearby gauging station. A new type of snail controlling revetment was also designed according to the idea of snail controlling by plants. Moreover, three experimental sections were created with different combinations of snail controlling plants. The site survey showed that both rigid revetment and ecological revetment were effective in controlling oncomelania. But the ecological revetment is more natural compared with the rigid one. Among the three test sections, the section with densely hairy sorrel smart weeds as emerged plants and leonurus as herbaceous plants had the highest plant survival rate.
Rigid revetment is widely used in traditional water conservancy and anti-schistosomiasis projects. It has a negative impact on the biological diversity of watercourses. A regular rigid revetment was designed for a water conservancy project based on the tidal data of a nearby gauging station. A new type of snail controlling revetment was also designed according to the idea of snail controlling by plants. Moreover, three experimental sections were created with different combinations of snail controlling plants. The site survey showed that both rigid revetment and ecological revetment were effective in controlling oncomelania. But the ecological revetment is more natural compared with the rigid one. Among the three test sections, the section with densely hairy sorrel smart weeds as emerged plants and leonurus as herbaceous plants had the highest plant survival rate.
2017, 15(1):107-112.
Abstract:
Jinsha River is a key area for hydropower construction in China and an ecological barrier of Yangtze River. Based on the temperature and precipitation data from standard meteorological stations and MODIS data, this paper studied the spatiotemporal variation of vegetation NDVI and related influence factors in the lower section of Jinsha River through correlation analysis, spatial statistical analysis, overlay analysis, and other methods. The results showed that during a year, changes of NDVI showed a single peak, with the lowest value at 0.55 in March and the highest value at 0.75 in September. Over the 10 years, the vegetation coverage showed an overall growing trend, with an NDVI growth rate of 0.05%/10a. There was spatial heterogeneity in the NDVI growth. Below 3850-m altitude, the vegetation NDVI generally gradually escalated with altitude, but it declined above 3850-m altitude. During a year, the impact of precipitation on vegetation NDVI was more obvious than that of air temperature, and the NDVI change was two months behind the precipitation and temperature. Over the years, temperature had more prominent influence on vegetation NDVI than precipitation. Besides, the large-scale conversion of farmland to forest had important contribution to the increase of NDVI in the lower section of Jinsha River.
Jinsha River is a key area for hydropower construction in China and an ecological barrier of Yangtze River. Based on the temperature and precipitation data from standard meteorological stations and MODIS data, this paper studied the spatiotemporal variation of vegetation NDVI and related influence factors in the lower section of Jinsha River through correlation analysis, spatial statistical analysis, overlay analysis, and other methods. The results showed that during a year, changes of NDVI showed a single peak, with the lowest value at 0.55 in March and the highest value at 0.75 in September. Over the 10 years, the vegetation coverage showed an overall growing trend, with an NDVI growth rate of 0.05%/10a. There was spatial heterogeneity in the NDVI growth. Below 3850-m altitude, the vegetation NDVI generally gradually escalated with altitude, but it declined above 3850-m altitude. During a year, the impact of precipitation on vegetation NDVI was more obvious than that of air temperature, and the NDVI change was two months behind the precipitation and temperature. Over the years, temperature had more prominent influence on vegetation NDVI than precipitation. Besides, the large-scale conversion of farmland to forest had important contribution to the increase of NDVI in the lower section of Jinsha River.
2017, 15(1):113-120.
Abstract:
To investigate the promoting effect of water movement on soil nutrients beneath the Tamarix chinensis shrubs in the coastal wetlands, we analyzed the soil organic matter at different locations and soil layers around a Tamarix chinensis and the isotopes of soil water, surface water, and Yellow River water. The results showed that: (1) Soil organic matter is enriched around the trunk of Tamarix chinensis shrubs, forming a 20-cm-deep enriched circle-layer with a 1.5-m radius. Soils under shrub canopy have significantly higher content of organic matter compared to those under the canopy edge and at the open spaces between plants. Deeper soils have less content, showing prominent “fertile island” effects. (2) The hydrogen and oxygen stable isotopes at different soil profiles were different. In the 0-5cm topsoil, the δD and δ18O isotopic values are from large to small under shrub canopy, under canopy edge, and at the open spaces. In the 5-10cm soil layer, the δD and δ18O isotopic values are from small to large under shrub canopy, under canopy edge, and at the open spaces. The isotopic values in the 0-5cm topsoil are greater than those in the 5-10cm soil layer. (3) Water movement has an effect on the content of organic matter. The nutrients carried by stemflow and the lateral seepage of the Yellow River are two of the reasons why the content of organic matter is from large to small under shrub canopy, under canopy edge, and at the open spaces. The enrichment of soil organic matter has changed the physicochemical properties of the soil around the plant. The small-scale spatial heterogeneity of soil nutrients has promoted the growth of the Tamarix chinensis and the surrounding plants. The research results can provide reference for the saline soil reclamation and vegetation recovery in the Yellow River Delta.
To investigate the promoting effect of water movement on soil nutrients beneath the Tamarix chinensis shrubs in the coastal wetlands, we analyzed the soil organic matter at different locations and soil layers around a Tamarix chinensis and the isotopes of soil water, surface water, and Yellow River water. The results showed that: (1) Soil organic matter is enriched around the trunk of Tamarix chinensis shrubs, forming a 20-cm-deep enriched circle-layer with a 1.5-m radius. Soils under shrub canopy have significantly higher content of organic matter compared to those under the canopy edge and at the open spaces between plants. Deeper soils have less content, showing prominent “fertile island” effects. (2) The hydrogen and oxygen stable isotopes at different soil profiles were different. In the 0-5cm topsoil, the δD and δ18O isotopic values are from large to small under shrub canopy, under canopy edge, and at the open spaces. In the 5-10cm soil layer, the δD and δ18O isotopic values are from small to large under shrub canopy, under canopy edge, and at the open spaces. The isotopic values in the 0-5cm topsoil are greater than those in the 5-10cm soil layer. (3) Water movement has an effect on the content of organic matter. The nutrients carried by stemflow and the lateral seepage of the Yellow River are two of the reasons why the content of organic matter is from large to small under shrub canopy, under canopy edge, and at the open spaces. The enrichment of soil organic matter has changed the physicochemical properties of the soil around the plant. The small-scale spatial heterogeneity of soil nutrients has promoted the growth of the Tamarix chinensis and the surrounding plants. The research results can provide reference for the saline soil reclamation and vegetation recovery in the Yellow River Delta.
2017, 15(1):121-125.
Abstract:
Radar measurement experiments were performed with a RIS K2 at the Toudaoguai Hydrological Station section in the winter of 2013-2014. The experiments detected ice thickness using radar with different frequency antenna and compared the detected thickness with measured thickness by drilling. The results showed the 200-MHz antenna can detect deeper depth below river ice and identify the frazil ice layer. The radar transmission speed in ice was determined based on the propagation time of radar electromagnetic wave and measured ice thickness. The radar transmission speed was about 16.3 cm/ns in the freezing period and less than 15.0 cm/ns in melting period. The GPR images showed that the thickness of the ice layer was not uniform along the section perpendicular to the course of river. In the main flow area between Pile No. 400 and No. 520, the maximum ice thickness was about 60 cm and the ice was mainly made up of granular ice and columnar ice created by thermodynamic growth. In the non-main flow area between Pile No. 520 and No. 740, the maximum ice thickness was about 70 cm and the ice was mainly made up of frazil ice. In addition, The GPR images can be used to locate the position and direction of the ice cracks in ice layer.
Radar measurement experiments were performed with a RIS K2 at the Toudaoguai Hydrological Station section in the winter of 2013-2014. The experiments detected ice thickness using radar with different frequency antenna and compared the detected thickness with measured thickness by drilling. The results showed the 200-MHz antenna can detect deeper depth below river ice and identify the frazil ice layer. The radar transmission speed in ice was determined based on the propagation time of radar electromagnetic wave and measured ice thickness. The radar transmission speed was about 16.3 cm/ns in the freezing period and less than 15.0 cm/ns in melting period. The GPR images showed that the thickness of the ice layer was not uniform along the section perpendicular to the course of river. In the main flow area between Pile No. 400 and No. 520, the maximum ice thickness was about 60 cm and the ice was mainly made up of granular ice and columnar ice created by thermodynamic growth. In the non-main flow area between Pile No. 520 and No. 740, the maximum ice thickness was about 70 cm and the ice was mainly made up of frazil ice. In addition, The GPR images can be used to locate the position and direction of the ice cracks in ice layer.
2017, 15(1):126-131.
Abstract:
In the seas and rivers in high-latitude regions, the broken ice floes can generate obvious ice load on offshore platform piles and bridge piers, and even cause damage of the vertical piles. Based on the discrete distribution characteristics of ice floes under natural conditions, the Voronoi cutting algorithm was used to construct the initial state of randomly-distributed broken ice floes with irregular geometric shapes. The discrete element method was adopted to simulate the drifting process of ice floes and the interaction between ice floes and vertical piles. The ice floe model with certain thickness, size, shape and other physical parameters was constructed with bonded spheres with consideration to their failure effect. The vertical piles were simplified as rigid structures. A numerical simulation was conducted to determine the ice load on the pile group under the impact of ice floes, and analyze the effects of ice size, ice velocity and ice thickness on the ice load of pile structures.
In the seas and rivers in high-latitude regions, the broken ice floes can generate obvious ice load on offshore platform piles and bridge piers, and even cause damage of the vertical piles. Based on the discrete distribution characteristics of ice floes under natural conditions, the Voronoi cutting algorithm was used to construct the initial state of randomly-distributed broken ice floes with irregular geometric shapes. The discrete element method was adopted to simulate the drifting process of ice floes and the interaction between ice floes and vertical piles. The ice floe model with certain thickness, size, shape and other physical parameters was constructed with bonded spheres with consideration to their failure effect. The vertical piles were simplified as rigid structures. A numerical simulation was conducted to determine the ice load on the pile group under the impact of ice floes, and analyze the effects of ice size, ice velocity and ice thickness on the ice load of pile structures.
2017, 15(1):132-137.
Abstract:
The middle route of the South-to-North Water Transfer project is long and runs across a wide range of altitudes, and it will suffer from the risks of ice clogging and damming during the freezing period. The risk of ice jam accumulation as well as the break-up pattern vary with the tortuosity, cross-section width and other geographical conditions of the channel. Therefore, it is necessary to study the spatial distribution of the ice hazards in order to realize hierarchical management of channels, save operating costs and increase the ability to deal with risks. This paper established a risk evaluation index system and evaluation model to obtain the spatial distribution of the ice hazards by quantifying the channel’s geographical conditions based on the fuzzy evaluation theory. First, four geographical indicators that predispose to ice hazards were obtained including longitudinal slope, tortuosity of channel, cross-section width and obstacles. And then, the quantitative method for geographical conditions was improved based on the mechanism of ice jam formation, and the risk evaluation index system was established. Lastly, the Beijing-Shijiazhuang section was taken as a case study, in which the risks of different canal reaches were evaluated with the proposed model by partitioning the section into multiple unit channels. Results showed that the ice hazards of a unit channel can fall into five levels, and the hazards are the largest in the Xihei Mountain Regulator – Baohe River Regulator Reach and Fenzhuang River Regulator – Nanjuma Regulator Reach. The research findings can offer some valuable guidance to ice damage prevention and control.
The middle route of the South-to-North Water Transfer project is long and runs across a wide range of altitudes, and it will suffer from the risks of ice clogging and damming during the freezing period. The risk of ice jam accumulation as well as the break-up pattern vary with the tortuosity, cross-section width and other geographical conditions of the channel. Therefore, it is necessary to study the spatial distribution of the ice hazards in order to realize hierarchical management of channels, save operating costs and increase the ability to deal with risks. This paper established a risk evaluation index system and evaluation model to obtain the spatial distribution of the ice hazards by quantifying the channel’s geographical conditions based on the fuzzy evaluation theory. First, four geographical indicators that predispose to ice hazards were obtained including longitudinal slope, tortuosity of channel, cross-section width and obstacles. And then, the quantitative method for geographical conditions was improved based on the mechanism of ice jam formation, and the risk evaluation index system was established. Lastly, the Beijing-Shijiazhuang section was taken as a case study, in which the risks of different canal reaches were evaluated with the proposed model by partitioning the section into multiple unit channels. Results showed that the ice hazards of a unit channel can fall into five levels, and the hazards are the largest in the Xihei Mountain Regulator – Baohe River Regulator Reach and Fenzhuang River Regulator – Nanjuma Regulator Reach. The research findings can offer some valuable guidance to ice damage prevention and control.
2017, 15(1):138-144.
Abstract:
Dongchuan Ms 7.8 earthquake happened on August 2nd, 1733, and the seismic hazards were completely recorded by Cui Naiyong, a local executive officer, in which the data are valuable to the study of secondary mountainous seismic hazards triggered by strike-slip seismic fault. The present paper investigated the secondary seismic hazards in the field based on the guide of the historical materials，the main conclusions were as follows: (1) the secondary mountainous seismic hazards were limited in a narrow zone along the seismic fracture; (2) weak support underground mines of copper were destroyed or seriously damaged, and the wooden building was good in seismic resistance; (3) the landslide failure showed in two different styles: projecting or slowly sliding, depending on the boundary conditions of the landslides or the failure time;(4) slope seismic shattering and loosening was one of the main reasons for the high-frequency debris flow.
Dongchuan Ms 7.8 earthquake happened on August 2nd, 1733, and the seismic hazards were completely recorded by Cui Naiyong, a local executive officer, in which the data are valuable to the study of secondary mountainous seismic hazards triggered by strike-slip seismic fault. The present paper investigated the secondary seismic hazards in the field based on the guide of the historical materials，the main conclusions were as follows: (1) the secondary mountainous seismic hazards were limited in a narrow zone along the seismic fracture; (2) weak support underground mines of copper were destroyed or seriously damaged, and the wooden building was good in seismic resistance; (3) the landslide failure showed in two different styles: projecting or slowly sliding, depending on the boundary conditions of the landslides or the failure time;(4) slope seismic shattering and loosening was one of the main reasons for the high-frequency debris flow.
2017, 15(1):145-149.
Abstract:
Dongjialiang landslide in Hualou Town of Wanyuan City is a typical red bed landslide in Sichuan Basin. Several means such as field annotation and engineering geological exploration were used to reveal that this landslide was a slide deformation and failure mainly caused by powerful water pressure. Based on the spatial shape and residue characteristics after the sliding, the landslide was divided into the promoter zone (Zone A), pushing slide zone at the west side of the landslide (Zone B), and traction slide zone at the east side (Zone C). The study showed that the landslide started from the central zone (Zone A) where groundwater activity was intense. The water pressure rose sharply as the rainfall increased. Pushed by the water pressure, the rock at this zone was exposed to shear failure along the surface and sideslip surface, forming a wedge sliding while pulling the rocks at Zones B and C to produce pushing, tension, and traction sliding failure.
Dongjialiang landslide in Hualou Town of Wanyuan City is a typical red bed landslide in Sichuan Basin. Several means such as field annotation and engineering geological exploration were used to reveal that this landslide was a slide deformation and failure mainly caused by powerful water pressure. Based on the spatial shape and residue characteristics after the sliding, the landslide was divided into the promoter zone (Zone A), pushing slide zone at the west side of the landslide (Zone B), and traction slide zone at the east side (Zone C). The study showed that the landslide started from the central zone (Zone A) where groundwater activity was intense. The water pressure rose sharply as the rainfall increased. Pushed by the water pressure, the rock at this zone was exposed to shear failure along the surface and sideslip surface, forming a wedge sliding while pulling the rocks at Zones B and C to produce pushing, tension, and traction sliding failure.
2017, 15(1):150-154.
Abstract:
In view of the sharp decline of groundwater level during the development and utilization of geothermal water resources at Xinji county in Central Hebei Plain, this paper studied the inter-annual and annual variation characteristics and trend of the groundwater level and the variation pattern of the water level decline in the geothermal field since 1999, as well as their relationship with the annual precipitation in the upstream mountains. The results showed that: (1) As geothermal water yield increases, the groundwater level of the geothermal field declines, and the growth of groundwater level at the non-heating period is decreasing year by year. (2) The development and utilization of the geothermal field is not simply consumption of groundwater storage resources. The groundwater level decline range is not only related to the amount of geothermal water yield, but also to the annual precipitation in the upstream mountains. As the annual precipitation increases (decreases), the decline of groundwater level decreases (increases). (3) The groundwater resources of the geothermal field have already been over-exploited. It is urgent to control the exploitation or increase the supply.
In view of the sharp decline of groundwater level during the development and utilization of geothermal water resources at Xinji county in Central Hebei Plain, this paper studied the inter-annual and annual variation characteristics and trend of the groundwater level and the variation pattern of the water level decline in the geothermal field since 1999, as well as their relationship with the annual precipitation in the upstream mountains. The results showed that: (1) As geothermal water yield increases, the groundwater level of the geothermal field declines, and the growth of groundwater level at the non-heating period is decreasing year by year. (2) The development and utilization of the geothermal field is not simply consumption of groundwater storage resources. The groundwater level decline range is not only related to the amount of geothermal water yield, but also to the annual precipitation in the upstream mountains. As the annual precipitation increases (decreases), the decline of groundwater level decreases (increases). (3) The groundwater resources of the geothermal field have already been over-exploited. It is urgent to control the exploitation or increase the supply.
2017, 15(1):155-160.
Abstract:
Due to the integrated effects of multiple factors, the classification of the swelling-shrinkage grade of expansive soils is one of the most difficult problems in expansive soil treatment. Five key factors were chosen to construct the model. By constructing standard samples through stochastic interpolation, we obtained the best projection direction and best projection values using the genetic algorithm and the projection pursuit method. Then we fitted a non-linear relationship between the best projection values and empirical values using the logistic curve function, and developed a new model for the classification of swelling-shrinkage grade of expansive soils, i.e., the genetic projection pursuit model. Finally, the new model was applied to actual engineering. The results tallied well with the actual situation, and thus verified the feasibility and applicability of the proposed model. This model can be a new method for classifying the swelling-shrinkage grade of expansive soils.
Due to the integrated effects of multiple factors, the classification of the swelling-shrinkage grade of expansive soils is one of the most difficult problems in expansive soil treatment. Five key factors were chosen to construct the model. By constructing standard samples through stochastic interpolation, we obtained the best projection direction and best projection values using the genetic algorithm and the projection pursuit method. Then we fitted a non-linear relationship between the best projection values and empirical values using the logistic curve function, and developed a new model for the classification of swelling-shrinkage grade of expansive soils, i.e., the genetic projection pursuit model. Finally, the new model was applied to actual engineering. The results tallied well with the actual situation, and thus verified the feasibility and applicability of the proposed model. This model can be a new method for classifying the swelling-shrinkage grade of expansive soils.
2017, 15(1):161-166.
Abstract:
To protect the downstream river bed and bank slope of the high dam from the serious erosion by high-speed flood flow, which will endanger dam safety, it is necessary to build all kinds of stilling pond protective structures as the first line of defense for dam safety. The security of all types of stilling pond protective structures is the premise for the safety of high dam flood discharge. As the studies on downstream protective works of the high dam dig deeper, floors of different structural forms have been proposed, such as the stilling pond floor with a keyway and the pervious floor, to increase the stability of the stilling pond. The form of the stilling pond also transformed from the "passive protection" model to the "active protection" model. This paper studied the pervious floor with a keyway that combines "active protection" with "passive protection". A model test was conducted to analyze the uplift force in terms of the maximum value, probability density distribution, amplitude, and power spectrum. The results showed: In comparison with the floor with a keyway, increasing permeable holes can reduce the uplift force. The probability density distribution of the uplift force basically conforms to the normal distribution. The magnitude of the uplift force is reduced. The power spectral density is even closer to a low frequency.
To protect the downstream river bed and bank slope of the high dam from the serious erosion by high-speed flood flow, which will endanger dam safety, it is necessary to build all kinds of stilling pond protective structures as the first line of defense for dam safety. The security of all types of stilling pond protective structures is the premise for the safety of high dam flood discharge. As the studies on downstream protective works of the high dam dig deeper, floors of different structural forms have been proposed, such as the stilling pond floor with a keyway and the pervious floor, to increase the stability of the stilling pond. The form of the stilling pond also transformed from the "passive protection" model to the "active protection" model. This paper studied the pervious floor with a keyway that combines "active protection" with "passive protection". A model test was conducted to analyze the uplift force in terms of the maximum value, probability density distribution, amplitude, and power spectrum. The results showed: In comparison with the floor with a keyway, increasing permeable holes can reduce the uplift force. The probability density distribution of the uplift force basically conforms to the normal distribution. The magnitude of the uplift force is reduced. The power spectral density is even closer to a low frequency.
2017, 15(1):167-172.
Abstract:
Research on the starting process of the axial flow pump is a very important part of the research on pump stations. In order to capture accurately the dynamic characteristics of an axial flow pump in the starting process, a three-dimensional geometrical model of the full passage was established. The CFD software Fluent, the dynamic mesh technology based on finite volume method, and the VOF multiphase flow model were all used to conduct three-dimensional transient numerical simulation of the axial flow pump, from which the variation patterns of external characteristic parameters were obtained. When the opening time of the gate was 60 s, the maximum head was 2.76 m at 12 s, which was 1.28 times of the rated head. Less starting time of the gate led to a lower starting head, but it aggravated the back-flow. The results showed that the dynamic mesh technology can be used in 3D numerical simulation of the starting transition process of an axial flow pump with a quick-stop gate. The results can help optimize the hydraulic parameters of pump stations and can be used as a reference for the research of the transition process of axial flow pump units.
Research on the starting process of the axial flow pump is a very important part of the research on pump stations. In order to capture accurately the dynamic characteristics of an axial flow pump in the starting process, a three-dimensional geometrical model of the full passage was established. The CFD software Fluent, the dynamic mesh technology based on finite volume method, and the VOF multiphase flow model were all used to conduct three-dimensional transient numerical simulation of the axial flow pump, from which the variation patterns of external characteristic parameters were obtained. When the opening time of the gate was 60 s, the maximum head was 2.76 m at 12 s, which was 1.28 times of the rated head. Less starting time of the gate led to a lower starting head, but it aggravated the back-flow. The results showed that the dynamic mesh technology can be used in 3D numerical simulation of the starting transition process of an axial flow pump with a quick-stop gate. The results can help optimize the hydraulic parameters of pump stations and can be used as a reference for the research of the transition process of axial flow pump units.
2017, 15(1):173-178.
Abstract:
There are many damage types of earthquake-damaged reservoirs, involving complex factors with strong interconnections. It has become a very realistic and urgent problem as to how to determine the damage quickly after the earthquake, so that the follow-up work on reinforcement can be conducted reasonably and orderly. In view of the specific problems with the selection of whitening weight functions and determination of clustering principles, we adopted the new idea of mixed triangular whitening weight function, put forward a method to analyze and evaluate earthquake-damaged reservoirs based on improved grey clustering, and applied the method to earthquake-damaged reservoirs in Sichuan. Analysis and evaluation results showed that the method has a simple structure, is able to sort the reservoirs by damage level rapidly and effectively, and thereby determine the reinforcement sequence of the reservoirs as well as and the critical procedures. Through comparison of various evaluation methods and analysis of the actual seismic damage, it was drawn that the improved gray clustering method is reliable, and can be well used in the analysis and evaluation of earthquake-damaged reservoirs. It is of great significance for preventing earthquake secondary disasters.
There are many damage types of earthquake-damaged reservoirs, involving complex factors with strong interconnections. It has become a very realistic and urgent problem as to how to determine the damage quickly after the earthquake, so that the follow-up work on reinforcement can be conducted reasonably and orderly. In view of the specific problems with the selection of whitening weight functions and determination of clustering principles, we adopted the new idea of mixed triangular whitening weight function, put forward a method to analyze and evaluate earthquake-damaged reservoirs based on improved grey clustering, and applied the method to earthquake-damaged reservoirs in Sichuan. Analysis and evaluation results showed that the method has a simple structure, is able to sort the reservoirs by damage level rapidly and effectively, and thereby determine the reinforcement sequence of the reservoirs as well as and the critical procedures. Through comparison of various evaluation methods and analysis of the actual seismic damage, it was drawn that the improved gray clustering method is reliable, and can be well used in the analysis and evaluation of earthquake-damaged reservoirs. It is of great significance for preventing earthquake secondary disasters.
2017, 15(1):179-185.
Abstract:
Finite element numerical calculation is widely used in hydraulic engineering. Its accuracy and error is one of the important problems that need to be considered and controlled. Studies on this issue can provide technical support for the FEM in the design and check of hydraulic engineering. Gravity dam was used as the object of research. The factors influencing the error in finite element stress calculation were analyzed by comparing the resultant load value of the gravity dam with the internal force value of the dam base surface from finite element calculation (integral value of stress of dam base surface). The results showed that extracting the stress from different objects results in different finite element calculation error, even under the same stress state. It is necessary to select the proper object to extract the stress from according to the research goal and error control requirements. The error can be greatly reduced by making the thin-layer foundation adjacent to the dam the same size and in the same constraint condition as the dam body. Proper determination on mesh size, simulation range of foundation, number of paths to extract the stress, and spacing of extracting points can meet the required precision without overly consuming resources or time. The results can provide reference for controlling the finite element calculation error in similar projects.
Finite element numerical calculation is widely used in hydraulic engineering. Its accuracy and error is one of the important problems that need to be considered and controlled. Studies on this issue can provide technical support for the FEM in the design and check of hydraulic engineering. Gravity dam was used as the object of research. The factors influencing the error in finite element stress calculation were analyzed by comparing the resultant load value of the gravity dam with the internal force value of the dam base surface from finite element calculation (integral value of stress of dam base surface). The results showed that extracting the stress from different objects results in different finite element calculation error, even under the same stress state. It is necessary to select the proper object to extract the stress from according to the research goal and error control requirements. The error can be greatly reduced by making the thin-layer foundation adjacent to the dam the same size and in the same constraint condition as the dam body. Proper determination on mesh size, simulation range of foundation, number of paths to extract the stress, and spacing of extracting points can meet the required precision without overly consuming resources or time. The results can provide reference for controlling the finite element calculation error in similar projects.
2017, 15(1):186-192.
Abstract:
Intakes of nuclear power plant in high-latitude coastal regions generally have ice problems that will affect their normal operation. One solution is to transport warm water to the forebay of pump stations through perforated drain-pipes. This method can raise water temperature and prevent ice jam. A physical model of perforated drain-pipe was used to study its hydraulic characteristics, including pressure distribution and velocity distribution. A non-dimensional formula of pressure distribution within the perforated drain-pipe was proposed and the maximum average error was 0.88%. The study shows that the pressure recovery within the perforated drain-pipe is caused by transformation from velocity to pressure. The larger the velocity, the more obvious the pressure recovery. The pressure of the downstream drain-pipe is larger than that of the upstream because the streamline is skewed near the outlet. The study results can provide references for the design and application of perforated drain-pipes.
Intakes of nuclear power plant in high-latitude coastal regions generally have ice problems that will affect their normal operation. One solution is to transport warm water to the forebay of pump stations through perforated drain-pipes. This method can raise water temperature and prevent ice jam. A physical model of perforated drain-pipe was used to study its hydraulic characteristics, including pressure distribution and velocity distribution. A non-dimensional formula of pressure distribution within the perforated drain-pipe was proposed and the maximum average error was 0.88%. The study shows that the pressure recovery within the perforated drain-pipe is caused by transformation from velocity to pressure. The larger the velocity, the more obvious the pressure recovery. The pressure of the downstream drain-pipe is larger than that of the upstream because the streamline is skewed near the outlet. The study results can provide references for the design and application of perforated drain-pipes.
2017, 15(1):193-198.
Abstract:
Energy dissipating fixed cone valve is used under medium or high water head, and the design of its internal structure directly affects its flow control efficiency. To study the changes of the valve’s internal flow field and flow rate when the closed switch is opened to varied degrees, the writer conducted model tests and CFD numerical simulation computation, and found that when the switch was turned down from 100% open to 85% open, the flow rate increased and pressure around the inlet dropped. The writer also conducted visualization research on the valve’s internal flow field through CFD numerical simulation, and the results showed the following problems inside the valve when the switch was fully open: excessively high speed and high pressure in partial areas, extensive low-flow stagnation areas, excess impact of eddy area on the high-speed flow area. Finally, the writer optimized the valve’s structure and its internal flow field.
Energy dissipating fixed cone valve is used under medium or high water head, and the design of its internal structure directly affects its flow control efficiency. To study the changes of the valve’s internal flow field and flow rate when the closed switch is opened to varied degrees, the writer conducted model tests and CFD numerical simulation computation, and found that when the switch was turned down from 100% open to 85% open, the flow rate increased and pressure around the inlet dropped. The writer also conducted visualization research on the valve’s internal flow field through CFD numerical simulation, and the results showed the following problems inside the valve when the switch was fully open: excessively high speed and high pressure in partial areas, extensive low-flow stagnation areas, excess impact of eddy area on the high-speed flow area. Finally, the writer optimized the valve’s structure and its internal flow field.
2017, 15(1):199-203.
Abstract:
In the slope stability analysis, the strength theory of saturated soil was commonly adopted in three-dimensional slope stability analysis, but in fact the effect of matric suction in unsaturated zone could not be ignored, so it is necessary to adopt the strength theory of unsaturated soil for slope stability analysis. Therefore, based on the strength theory of unsaturated soil and thought of three-dimensional simplified Bishop’s method, a new formula of safety factor was deduced to evaluate slope stability and corresponding program was developed. Finally, the slope stability of Sima reach in Yangtze river was analyzed using the proposed method, the results indicated that the safety factor was increased based on strength theory of unsaturated soil compared to strength theory of saturated soil and it was more reasonable to evaluate slope stability by the proposed method.
In the slope stability analysis, the strength theory of saturated soil was commonly adopted in three-dimensional slope stability analysis, but in fact the effect of matric suction in unsaturated zone could not be ignored, so it is necessary to adopt the strength theory of unsaturated soil for slope stability analysis. Therefore, based on the strength theory of unsaturated soil and thought of three-dimensional simplified Bishop’s method, a new formula of safety factor was deduced to evaluate slope stability and corresponding program was developed. Finally, the slope stability of Sima reach in Yangtze river was analyzed using the proposed method, the results indicated that the safety factor was increased based on strength theory of unsaturated soil compared to strength theory of saturated soil and it was more reasonable to evaluate slope stability by the proposed method.
34 Operation scheme for maximum opening test of check gates in South-to-North
Water Diversion Project
2017, 15(1):204-208.
Abstract:
The Middle Route Project (MRP) of South-to-North Water Diversion (SNWD) has 64 check gates. The check gates need to be tested under the flowing water from zero to the maximum opening to ensure the safe operation of the SNWD project. Certain operation measures need to be taken in order to complete the maximum opening test when the dividing gates have not yet met the design discharge. This article analyzed the feasibility of a maximum opening test based on a typical check gate, and compared the operation scheme across several specific conditions. After preliminary study, it selected the scheme of “adjusting the water level of local canal reaches with control gates”, where the hydraulic conditions of upstream and downstream control structures of the piloting check gate were adjusted to ensure relatively stable water supply and water level at the piloting check gate and the upstream and downstream canal reaches, thus realizing the maximum opening test.
The Middle Route Project (MRP) of South-to-North Water Diversion (SNWD) has 64 check gates. The check gates need to be tested under the flowing water from zero to the maximum opening to ensure the safe operation of the SNWD project. Certain operation measures need to be taken in order to complete the maximum opening test when the dividing gates have not yet met the design discharge. This article analyzed the feasibility of a maximum opening test based on a typical check gate, and compared the operation scheme across several specific conditions. After preliminary study, it selected the scheme of “adjusting the water level of local canal reaches with control gates”, where the hydraulic conditions of upstream and downstream control structures of the piloting check gate were adjusted to ensure relatively stable water supply and water level at the piloting check gate and the upstream and downstream canal reaches, thus realizing the maximum opening test.
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