Volume 15,Issue 2,2017 Table of Contents
2017, 15(2):1-8.
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.
2 Social spider optimization-based projection pursuit model to predict annual maximum flood peak flow
2017, 15(2):9-14.
Abstract:
The prediction of annual maximum flood peak flow is affected by many complicated factors and highly indeterminate, making it difficult to deliver accurate forecasts by conventional statistical methods. In this paper, based on hydrological sequence itself, we proposed that the projection regression model be used to predict the annual maximum flood peak flow. In order to obtain the optimal parameters for the projection pursuit model and improve prediction accuracy, we proposed the hybrid intelligence-based prediction model for annual maximum flood peak flow, in which the delay correlation coefficient method was used to determine the regression prediction factor, the social spider optimization algorithm to optimize the optimal projection direction parameter a of the projection pursuit model, the least square method to determine the weight coefficient c of the polynomial, and qualified rate to control the number of parameter M. The annual maximum flood peak flow data of Yichang Gauging Station of Yangtze River (1882 - 2004) were used to test the proposed model. The results indicated that the model can obtain very good prediction results, with a mean absolute relative error of 8.61% in the training phase, and a mean absolute relative error of 10.51% in the testing phase. The model can produce stable results and can be effectively applied to the prediction of annual maximum flood peak flow.
The prediction of annual maximum flood peak flow is affected by many complicated factors and highly indeterminate, making it difficult to deliver accurate forecasts by conventional statistical methods. In this paper, based on hydrological sequence itself, we proposed that the projection regression model be used to predict the annual maximum flood peak flow. In order to obtain the optimal parameters for the projection pursuit model and improve prediction accuracy, we proposed the hybrid intelligence-based prediction model for annual maximum flood peak flow, in which the delay correlation coefficient method was used to determine the regression prediction factor, the social spider optimization algorithm to optimize the optimal projection direction parameter a of the projection pursuit model, the least square method to determine the weight coefficient c of the polynomial, and qualified rate to control the number of parameter M. The annual maximum flood peak flow data of Yichang Gauging Station of Yangtze River (1882 - 2004) were used to test the proposed model. The results indicated that the model can obtain very good prediction results, with a mean absolute relative error of 8.61% in the training phase, and a mean absolute relative error of 10.51% in the testing phase. The model can produce stable results and can be effectively applied to the prediction of annual maximum flood peak flow.
2017, 15(2):15-21.
Abstract:
Research on the natural zoning of drought can reveal the law of drought occurrence and development in the study area. It can also provide theoretical basis for formulating countermeasures against drought disasters. Based on the principal component cluster analysis method, we chose the relief degree of land surface, annual average drought index, percentage of precipitation negative anomaly in low-flow years (P=75%), and variation coefficient of annual precipitation for natural zoning of drought in Yunnan province. With the ArcGis software, we plotted the natural zoning diagram of drought. Finally, single-factor analysis of variance was adopted to verify the rationality of zoning results. The results indicated that the central and eastern regions in Yunnan province are more susceptible to drought than the western regions. This finding is basically consistent with the statistical analysis results of relevant yearbooks and data. The differences among the four drought regions are remarkable, which can further verify that the natural zoning results of drought are reasonable in this paper.
Research on the natural zoning of drought can reveal the law of drought occurrence and development in the study area. It can also provide theoretical basis for formulating countermeasures against drought disasters. Based on the principal component cluster analysis method, we chose the relief degree of land surface, annual average drought index, percentage of precipitation negative anomaly in low-flow years (P=75%), and variation coefficient of annual precipitation for natural zoning of drought in Yunnan province. With the ArcGis software, we plotted the natural zoning diagram of drought. Finally, single-factor analysis of variance was adopted to verify the rationality of zoning results. The results indicated that the central and eastern regions in Yunnan province are more susceptible to drought than the western regions. This finding is basically consistent with the statistical analysis results of relevant yearbooks and data. The differences among the four drought regions are remarkable, which can further verify that the natural zoning results of drought are reasonable in this paper.
2017, 15(2):22-28.
Abstract:
Based on the annual precipitation in West Liao River Basin from 1961 to 2014, we established a variation diagnosis system that integrated preliminary diagnosis, which was based on hydrograph, moving average, and Hurst index, with detailed diagnosis, which was based on correlation coefficient, Mann-Kendall mutation test, moving T-test, and wavelet analysis. We also focused on the spatial-temporal distribution of the annual precipitation in the recent ten years (2005~2014), and compared the annual mean precipitation in this period with the annual mean precipitation during the five periods of 1961-2014, 1961-1970, 1971-1980, 1981-1990, and 1991-2000. Using the Kriging method, we described the spatial-temporal variation of the precipitation in the recent ten years on ArcGIS Platform. The results showed that the annual precipitation during 1961-2014 was slightly decreasing, but with a potential to increase in the future. Its primary periods were 6, 18 or 30a. The year of 1998 witnessed an abrupt change in the annual precipitation. Regarding spatial distribution, the variation degree of annual precipitation generally expanded from the southwest and east of the basin to the north. The recent ten years were dry years. The precipitation in this period was generally less than that in the above-mentioned five periods.
Based on the annual precipitation in West Liao River Basin from 1961 to 2014, we established a variation diagnosis system that integrated preliminary diagnosis, which was based on hydrograph, moving average, and Hurst index, with detailed diagnosis, which was based on correlation coefficient, Mann-Kendall mutation test, moving T-test, and wavelet analysis. We also focused on the spatial-temporal distribution of the annual precipitation in the recent ten years (2005~2014), and compared the annual mean precipitation in this period with the annual mean precipitation during the five periods of 1961-2014, 1961-1970, 1971-1980, 1981-1990, and 1991-2000. Using the Kriging method, we described the spatial-temporal variation of the precipitation in the recent ten years on ArcGIS Platform. The results showed that the annual precipitation during 1961-2014 was slightly decreasing, but with a potential to increase in the future. Its primary periods were 6, 18 or 30a. The year of 1998 witnessed an abrupt change in the annual precipitation. Regarding spatial distribution, the variation degree of annual precipitation generally expanded from the southwest and east of the basin to the north. The recent ten years were dry years. The precipitation in this period was generally less than that in the above-mentioned five periods.
2017, 15(2):29-36.
Abstract:
Using the moving average, cumulative departure, and linear tendency estimate methods, this paper investigated the precipitation characteristics of Weihe River basin during 1961-2013. The abrupt runoff changes were analyzed using the smoothing t test, orderly clustering, and double mass curve methods. The results showed that the precipitation in the Weihe River basin was generally decreasing, with 86 rainy days in an average year. The precipitation varied in different seasons, and was mainly concentrated in summer and autumn; it obviously decreased in spring and autumn. The number of heavy rainy days was significantly correlated with the annual average precipitation; the larger the annual average precipitation, the more frequent the heavy rainy days in an average year. Rainstorm intensity was increasing in the west and north of Weihe River basin, but was slightly decreasing in the east and south. The runoff in Huaxian had an abrupt change in the early 1970s and early 1990s. The precipitation variation was basically consistent with the runoff variation trend.
Using the moving average, cumulative departure, and linear tendency estimate methods, this paper investigated the precipitation characteristics of Weihe River basin during 1961-2013. The abrupt runoff changes were analyzed using the smoothing t test, orderly clustering, and double mass curve methods. The results showed that the precipitation in the Weihe River basin was generally decreasing, with 86 rainy days in an average year. The precipitation varied in different seasons, and was mainly concentrated in summer and autumn; it obviously decreased in spring and autumn. The number of heavy rainy days was significantly correlated with the annual average precipitation; the larger the annual average precipitation, the more frequent the heavy rainy days in an average year. Rainstorm intensity was increasing in the west and north of Weihe River basin, but was slightly decreasing in the east and south. The runoff in Huaxian had an abrupt change in the early 1970s and early 1990s. The precipitation variation was basically consistent with the runoff variation trend.
2017, 15(2):37-44.
Abstract:
Multi-scale observation and simulation of soil water is a hot research topic worldwide. Ground penetrating radar (GPR), as a modern technology for measuring soil water content, has filled in the scale gap between the traditional measuring method and the remote sensing method. Domestic and foreign research has showed that GPR is highly precise and fast for the measurement of soil water content, and does not destroy the soil structure. As a field-scale measurement method, it plays a unique role in determining the spatial distribution of meso- and micro-scale soil water at the depth of 0.05 m to 50 m. GPR has more advantages than TDR in precision verification and calibration of remote sensing retrieval model for soil water, and has the potential to be applied in remote sensing product validation and other hydrological applications. This paper can provide theoretical reference for related research and promotion of soil water measurement method by GPR.
Multi-scale observation and simulation of soil water is a hot research topic worldwide. Ground penetrating radar (GPR), as a modern technology for measuring soil water content, has filled in the scale gap between the traditional measuring method and the remote sensing method. Domestic and foreign research has showed that GPR is highly precise and fast for the measurement of soil water content, and does not destroy the soil structure. As a field-scale measurement method, it plays a unique role in determining the spatial distribution of meso- and micro-scale soil water at the depth of 0.05 m to 50 m. GPR has more advantages than TDR in precision verification and calibration of remote sensing retrieval model for soil water, and has the potential to be applied in remote sensing product validation and other hydrological applications. This paper can provide theoretical reference for related research and promotion of soil water measurement method by GPR.
2017, 15(2):45-49.
Abstract:
Buha River is the most important recharging source for Qinghai Lake. Analysis of the evolution of climate characteristics in Buha River basin has important significance to the ecological safety of Qinghai Lake. Based on the long series of temperature and precipitation data at Tianjun, Gangcha and Chaka stations, the climate characteristics in the river basin were analyzed. The results showed that the annual mean temperature continues to rise significantly at all the three stations. At Tianjun the highest station, the annual mean temperature has increased the most. Among the four seasons, the temperature increases the most in winter. Mann-Kendall trend analysis method and cumulative anomalies were used to analyze the temperature change over the time. The temperature rise had a 10-year fluctuation period from 1986 to 1997, and then went through a significantly abrupt change in 1997. This coincides with the variation trend of temperature and precipitation on Qinghai-Tibet Plateau over the years. The annual precipitation also has increased, but not so significantly as the annual mean temperature. The increase is more significant at the higher station. Among the four seasons, the annual precipitation increases the most in summer. According to the temperature and the available precipitation, the basin is going through a continuous warm and wet period since the 1980’s. It was relatively warm and dry in the 1990’s, and then became warm and wet again in the first decade of this century.
Buha River is the most important recharging source for Qinghai Lake. Analysis of the evolution of climate characteristics in Buha River basin has important significance to the ecological safety of Qinghai Lake. Based on the long series of temperature and precipitation data at Tianjun, Gangcha and Chaka stations, the climate characteristics in the river basin were analyzed. The results showed that the annual mean temperature continues to rise significantly at all the three stations. At Tianjun the highest station, the annual mean temperature has increased the most. Among the four seasons, the temperature increases the most in winter. Mann-Kendall trend analysis method and cumulative anomalies were used to analyze the temperature change over the time. The temperature rise had a 10-year fluctuation period from 1986 to 1997, and then went through a significantly abrupt change in 1997. This coincides with the variation trend of temperature and precipitation on Qinghai-Tibet Plateau over the years. The annual precipitation also has increased, but not so significantly as the annual mean temperature. The increase is more significant at the higher station. Among the four seasons, the annual precipitation increases the most in summer. According to the temperature and the available precipitation, the basin is going through a continuous warm and wet period since the 1980’s. It was relatively warm and dry in the 1990’s, and then became warm and wet again in the first decade of this century.
2017, 15(2):50-57.
Abstract:
The lack of water and the imbalance between supply and demand of water resources are both serious problems in Tuhai River Basin. However, in this basin, rainfall in the flood season is abundant, and the storage and detention engineering is excellent. Therefore, we put forward an idea to improve the utilization of rain-flood resources by properly operating the multi-stage sluices on the main channel to relieve the contradiction between supply and demand. We used MIKE11 software to establish a simulation model on rain-flood resources, coupled the hydrodynamic model (HD) and rainfall runoff model (NAM), and designed three operation modes: full-open gate, water level control, and water level difference control. We used these three modes to simulate the rain and flood process in typical working conditions. Based on the results of simulation, we carried out quantitative analysis of water regulation using the water quantity regulation calculation method. The results showed that the operation of the sluices can improve the utilization of rain-flood resources and solve the water resources crisis better.
The lack of water and the imbalance between supply and demand of water resources are both serious problems in Tuhai River Basin. However, in this basin, rainfall in the flood season is abundant, and the storage and detention engineering is excellent. Therefore, we put forward an idea to improve the utilization of rain-flood resources by properly operating the multi-stage sluices on the main channel to relieve the contradiction between supply and demand. We used MIKE11 software to establish a simulation model on rain-flood resources, coupled the hydrodynamic model (HD) and rainfall runoff model (NAM), and designed three operation modes: full-open gate, water level control, and water level difference control. We used these three modes to simulate the rain and flood process in typical working conditions. Based on the results of simulation, we carried out quantitative analysis of water regulation using the water quantity regulation calculation method. The results showed that the operation of the sluices can improve the utilization of rain-flood resources and solve the water resources crisis better.
9 Parameter analysis of wolf pack search algorithm applied to optimal operation of hydropower station
2017, 15(2):58-64.
Abstract:
Using the single factor analysis method, we analyzed and evaluated the influence of each parameter of wolf pack search algorithm on the optimization effects of the optimal operation model for hydropower stations, and obtained the effective value range of the parameters. The orthogonal test and range analysis method were used to comprehensively analyze the susceptibility of multiple parameters of wolf pack search algorithm, and to obtain the sensitivity rankings and optimal value combination of the parameters. Simulation results in the cases showed that the effective value range and optimal value combination of the parameters have a positive effect on the optimization performance of the proposed algorithm, and can provide basis for parameter selection for the wolf pack search algorithm applied to optimal operation of hydropower station.
Using the single factor analysis method, we analyzed and evaluated the influence of each parameter of wolf pack search algorithm on the optimization effects of the optimal operation model for hydropower stations, and obtained the effective value range of the parameters. The orthogonal test and range analysis method were used to comprehensively analyze the susceptibility of multiple parameters of wolf pack search algorithm, and to obtain the sensitivity rankings and optimal value combination of the parameters. Simulation results in the cases showed that the effective value range and optimal value combination of the parameters have a positive effect on the optimization performance of the proposed algorithm, and can provide basis for parameter selection for the wolf pack search algorithm applied to optimal operation of hydropower station.
2017, 15(2):65-72.
Abstract:
In order to further explore the impact of human activities on the variation characteristics of runoffs, taking the Jinjiang River Basin in southeast coastal region of China as the study area, this paper studied the variation tendency, abrupt and periodic changes of the runoff, using the Mann-Kendall nonparametric test, Curve-Rank test, and wavelet analysis method, based on the monthly runoff and precipitation data from 1960 to 2010. The Slop Changing Ratio of Cumulative Quantity method (SCRCQ) was employed to quantitatively assess the contribution of climate change and human activities to the variations of the annual runoff and seasonal distribution characteristics at Shilong hydrological station. The results showed that, under the influences of the inter-basin water diversion project and Shanmei reservoir’s regulation, the increasing tendency of the annual runoff at Shilong station was more prominent than that at Anxi station, which was not influenced by the reservoir; and the monthly runoff variations at Shilong station were more gentle. There were significant periodic variations of the annual and inter-annual runoff series at the three scales of 6-7a, 11-12a and 20-21a. They were basically consistent with the annual and inter-annual precipitation in the basin. However, a slight discrepancy occurred between the periodic runoff variations at Shilong station and periodic precipitation variations in the basin after the 1980s. There was an abrupt change in 1982 in the annual runoff series at Shilong station, but not at Anxi station. During the period of variation, the human activities as mainly represented by Shanmei reservoir contributed to 67.17% of the annual runoff variation, 84.76% of the annual unevenness coefficient variation, and 71.16% of the concentration degree variation at Shilong hydrological station.
In order to further explore the impact of human activities on the variation characteristics of runoffs, taking the Jinjiang River Basin in southeast coastal region of China as the study area, this paper studied the variation tendency, abrupt and periodic changes of the runoff, using the Mann-Kendall nonparametric test, Curve-Rank test, and wavelet analysis method, based on the monthly runoff and precipitation data from 1960 to 2010. The Slop Changing Ratio of Cumulative Quantity method (SCRCQ) was employed to quantitatively assess the contribution of climate change and human activities to the variations of the annual runoff and seasonal distribution characteristics at Shilong hydrological station. The results showed that, under the influences of the inter-basin water diversion project and Shanmei reservoir’s regulation, the increasing tendency of the annual runoff at Shilong station was more prominent than that at Anxi station, which was not influenced by the reservoir; and the monthly runoff variations at Shilong station were more gentle. There were significant periodic variations of the annual and inter-annual runoff series at the three scales of 6-7a, 11-12a and 20-21a. They were basically consistent with the annual and inter-annual precipitation in the basin. However, a slight discrepancy occurred between the periodic runoff variations at Shilong station and periodic precipitation variations in the basin after the 1980s. There was an abrupt change in 1982 in the annual runoff series at Shilong station, but not at Anxi station. During the period of variation, the human activities as mainly represented by Shanmei reservoir contributed to 67.17% of the annual runoff variation, 84.76% of the annual unevenness coefficient variation, and 71.16% of the concentration degree variation at Shilong hydrological station.
2017, 15(2):73-79.
Abstract:
Sensitivity analysis of model parameters is the basic work of flood forecasting. Based on the platform of Chinese flood forecasting system, we conducted sensitivity analysis of the parameters of MSKLOSS river flood routing model using the local analysis method, so as to improve the accuracy of flood forecasting. In order to improve the application efficiency of MSKLOSS river flood routing model, considering the applicability of the model and the convenience of simulation and analysis, we selected three flood locations at the south of Haihe river, which were Huangbizhuang to Beizhongshan of Hutuo River, Yuecheng to Caixiaozhuang of South Canal in August 1996, and Dongcicun to Xingaifang of Daqing River in July 2012, where the underlying surface of the river is close to the present condition. Results showed that the number of river segments, initial infiltration rate, infiltration curve index, and wetted perimeter are highly sensitive. Steady infiltration rate is more sensitive when the flood magnitude is small. Attention should be paid to the initial range setting during parameter optimization and real-time operational forecast.
Sensitivity analysis of model parameters is the basic work of flood forecasting. Based on the platform of Chinese flood forecasting system, we conducted sensitivity analysis of the parameters of MSKLOSS river flood routing model using the local analysis method, so as to improve the accuracy of flood forecasting. In order to improve the application efficiency of MSKLOSS river flood routing model, considering the applicability of the model and the convenience of simulation and analysis, we selected three flood locations at the south of Haihe river, which were Huangbizhuang to Beizhongshan of Hutuo River, Yuecheng to Caixiaozhuang of South Canal in August 1996, and Dongcicun to Xingaifang of Daqing River in July 2012, where the underlying surface of the river is close to the present condition. Results showed that the number of river segments, initial infiltration rate, infiltration curve index, and wetted perimeter are highly sensitive. Steady infiltration rate is more sensitive when the flood magnitude is small. Attention should be paid to the initial range setting during parameter optimization and real-time operational forecast.
2017, 15(2):80-88.
Abstract:
A SWAT hydrological model was constructed on the Miyun Reservoir catchment, and the parameters of the model were adjusted according to the actual water quantity and quality data. Based on SWAT simulation results, the critical areas of soil erosion and pollution were identified, and the effects of different management measures on water quantity and quality were analyzed quantitatively. The results are as follows. The areas of intense soil erosion are concentrated near the river in the middle and lower reaches of the Miyun Reservoir catchment. The non-point source pollution in the Chao River watershed is more serious. The areas with ultra-high risk of TN loss in Chao River and Bai River watersheds respectively account for 62.62% and 43.09% of the total areas. Bai River watershed has low risk of TP loss, while in Chao River watershed, the areas with high risk of TP loss account for 17.81%; Contour farming and terraced planting are both effective in reducing the amount of runoff, sediments, and pollutant load. Contour farming has reduced 25.16% of sediments, 10.79% of TN, and 32.89% of TP in Chao River watershed, and 47.60% of sediments, 34.92% of TN, and 53.49% of TP in Bai River watershed. Returning farmland to forests is more effective in pollutant reduction than returning farmland to grasslands. The research results can provide basis for decision-making in soil and water conservation and water environment rehabilitation in the Miyun Reservoir catchment.
A SWAT hydrological model was constructed on the Miyun Reservoir catchment, and the parameters of the model were adjusted according to the actual water quantity and quality data. Based on SWAT simulation results, the critical areas of soil erosion and pollution were identified, and the effects of different management measures on water quantity and quality were analyzed quantitatively. The results are as follows. The areas of intense soil erosion are concentrated near the river in the middle and lower reaches of the Miyun Reservoir catchment. The non-point source pollution in the Chao River watershed is more serious. The areas with ultra-high risk of TN loss in Chao River and Bai River watersheds respectively account for 62.62% and 43.09% of the total areas. Bai River watershed has low risk of TP loss, while in Chao River watershed, the areas with high risk of TP loss account for 17.81%; Contour farming and terraced planting are both effective in reducing the amount of runoff, sediments, and pollutant load. Contour farming has reduced 25.16% of sediments, 10.79% of TN, and 32.89% of TP in Chao River watershed, and 47.60% of sediments, 34.92% of TN, and 53.49% of TP in Bai River watershed. Returning farmland to forests is more effective in pollutant reduction than returning farmland to grasslands. The research results can provide basis for decision-making in soil and water conservation and water environment rehabilitation in the Miyun Reservoir catchment.
2017, 15(2):89-94.
Abstract:
Algal bloom risk is not only an environmental issue to be considered in water conservancy project planning, but also a monitoring item that cannot be ignored in the operation of water conservancy facilities. In order to improve the prediction accuracy for algal bloom risk of open channels, a risk assessment model for algal bloom of open channels was proposed based on the dynamic Na?ve Bayes classifier, with consideration to the uncertainty of the cause of algal bloom and sequential nature of its development. The risk grade nodes of the proposed model correspond to the concentration of chlorophyll a (Chla), and take into consideration 9 factors affecting the growth of algae. Network parameters were designed according to the results of expert consultation using the principal component analysis method. Based on the 53 cases of consecutive monitoring data observed from June 2011 to September 2011 at Beimen Bridge on Suzhou River, comparison was made between the proposed model and the assessment model based on Na?ve Bayes classifier. Confusion matrix results showed that the prediction accuracy for medium risks increased by 15.625%. Single tailed paired t-test showed that the recognition rates of the two models were significantly different when the significance level was 0.05. The assessment model based on dynamic Na?ve Bayes classifier with consideration to time sequence has significantly higher prediction and recognition rates for medium algal bloom risk of open channels.
Algal bloom risk is not only an environmental issue to be considered in water conservancy project planning, but also a monitoring item that cannot be ignored in the operation of water conservancy facilities. In order to improve the prediction accuracy for algal bloom risk of open channels, a risk assessment model for algal bloom of open channels was proposed based on the dynamic Na?ve Bayes classifier, with consideration to the uncertainty of the cause of algal bloom and sequential nature of its development. The risk grade nodes of the proposed model correspond to the concentration of chlorophyll a (Chla), and take into consideration 9 factors affecting the growth of algae. Network parameters were designed according to the results of expert consultation using the principal component analysis method. Based on the 53 cases of consecutive monitoring data observed from June 2011 to September 2011 at Beimen Bridge on Suzhou River, comparison was made between the proposed model and the assessment model based on Na?ve Bayes classifier. Confusion matrix results showed that the prediction accuracy for medium risks increased by 15.625%. Single tailed paired t-test showed that the recognition rates of the two models were significantly different when the significance level was 0.05. The assessment model based on dynamic Na?ve Bayes classifier with consideration to time sequence has significantly higher prediction and recognition rates for medium algal bloom risk of open channels.
2017, 15(2):95-100.
Abstract:
Chlorophyll-a concentration at Guanting Reservoir in summer (August) were analyzed. The analysis has great significance to the study of reservoir water eutrophication. The data of water temperature, water depth, chlorophyll-a concentration, and meteorological data were measured at an interval of one minute, and were analyzed. The results showed that the maximum concentration of chlorophyll-a appeared at basically the same position as that of the thermocline, and it was 1.5-2 times of the surface concentration value. Chlorophyll-a concentration showed circadian variation. During daytime, chlorophyll-a concentration above the thermocline increased as water depth increased; yet below the thermocline, it decreased as water depth increased. At night, the chlorophyll-a concentration below the thermocline had the same variation trend as it had in the daytime; but above the thermocline, it was basically stable. The surface chlorophyll-a concentration was higher at night than during the daytime, and showed a negative correlation with the surface temperature and illumination. The short-term distribution of chlorophyll-a concentration at Guanting Reservoir in summer was mainly related to the temperature stratification and the release of the limiting nutrient phosphorus.
Chlorophyll-a concentration at Guanting Reservoir in summer (August) were analyzed. The analysis has great significance to the study of reservoir water eutrophication. The data of water temperature, water depth, chlorophyll-a concentration, and meteorological data were measured at an interval of one minute, and were analyzed. The results showed that the maximum concentration of chlorophyll-a appeared at basically the same position as that of the thermocline, and it was 1.5-2 times of the surface concentration value. Chlorophyll-a concentration showed circadian variation. During daytime, chlorophyll-a concentration above the thermocline increased as water depth increased; yet below the thermocline, it decreased as water depth increased. At night, the chlorophyll-a concentration below the thermocline had the same variation trend as it had in the daytime; but above the thermocline, it was basically stable. The surface chlorophyll-a concentration was higher at night than during the daytime, and showed a negative correlation with the surface temperature and illumination. The short-term distribution of chlorophyll-a concentration at Guanting Reservoir in summer was mainly related to the temperature stratification and the release of the limiting nutrient phosphorus.
2017, 15(2):101-108.
Abstract:
In the semi-humid climate, the surface soil of coastal reclaimed land is faced with a complicated salinization problem. To investigate the formation mechanism of saline soil in coastal reclaimed land, we studied the salt migration process under the joint action of phreatic evaporation and lateral interflow. The results showed that the initial salt type in the surface soil is CaSO4, and it gradually transitions to CaCl2 and NaCl in the salt accumulation process. Under the action of terrestrial seepage, a stable wetting front moves to the coast while the water table rises. The area above the free water surface is in a salt accumulation state, with CaCl2 and MgSO4 as primary salt types. The area below the free water surface is in a state of desalination, with CaCl2 and NaCl as primary salt types. Water and salt movement will change the pH value of the soil environment. The pH value will first increase and then decline as the salt content increases. Under the condition of terrestrial groundwater recharge, the salinization prevention and control work in coastal reclaimed land should focus on areas with underground water barriers or densely distributed building foundations.
In the semi-humid climate, the surface soil of coastal reclaimed land is faced with a complicated salinization problem. To investigate the formation mechanism of saline soil in coastal reclaimed land, we studied the salt migration process under the joint action of phreatic evaporation and lateral interflow. The results showed that the initial salt type in the surface soil is CaSO4, and it gradually transitions to CaCl2 and NaCl in the salt accumulation process. Under the action of terrestrial seepage, a stable wetting front moves to the coast while the water table rises. The area above the free water surface is in a salt accumulation state, with CaCl2 and MgSO4 as primary salt types. The area below the free water surface is in a state of desalination, with CaCl2 and NaCl as primary salt types. Water and salt movement will change the pH value of the soil environment. The pH value will first increase and then decline as the salt content increases. Under the condition of terrestrial groundwater recharge, the salinization prevention and control work in coastal reclaimed land should focus on areas with underground water barriers or densely distributed building foundations.
2017, 15(2):109-115.
Abstract:
Considering the coexistence of environmental flow shortages and pollution problems of northern rivers, the concept and content of environmental flow were defined with consideration to water quality protection and water quantity maintenance. The composition of environmental flow under different functional goals was also discussed. By analyzing the characteristics of river systems and spatial structure features of river reaches, we established the environmental flow calculation model for improving water quality, and also established the Tennant and Wetted Perimeter models for calculating the environmental flow for river ecosystems. Using the hydrology and water quality data of Gaocun Bridge section, we conducted a preliminary evaluation of the environmental flow for improving the water quality and ecosystem of Qingyi River. This study provided flow regulatory advice for the emergency replenishment of water, and suggested the river flow levels that should be maintained constantly in different months of a year.
Considering the coexistence of environmental flow shortages and pollution problems of northern rivers, the concept and content of environmental flow were defined with consideration to water quality protection and water quantity maintenance. The composition of environmental flow under different functional goals was also discussed. By analyzing the characteristics of river systems and spatial structure features of river reaches, we established the environmental flow calculation model for improving water quality, and also established the Tennant and Wetted Perimeter models for calculating the environmental flow for river ecosystems. Using the hydrology and water quality data of Gaocun Bridge section, we conducted a preliminary evaluation of the environmental flow for improving the water quality and ecosystem of Qingyi River. This study provided flow regulatory advice for the emergency replenishment of water, and suggested the river flow levels that should be maintained constantly in different months of a year.
2017, 15(2):116-121.
Abstract:
The continuous shrinking of wetland area will lead to the continuous decline of the ecological functions of natural wetlands. In order to help wetlands to maintain a certain area, we should predict the natural area of wetlands first. In this paper, we used Momoge wetland in Jilin Province of China as the object of study to predict wetland area. First, we analyzed the main impact factors and their different influence on the area of Momoge wetland. We used the method of fuzzy reasoning method, which could well adapt to the highly nonlinear characteristics of multi-factor prediction. The results showed that the prediction accuracy of the fuzzy reasoning method is better than that of the multiple regression analysis method. The fuzzy reasoning method can be used in the studies of multi-index nonlinear prediction, evaluation, and classification in many engineering fields.
The continuous shrinking of wetland area will lead to the continuous decline of the ecological functions of natural wetlands. In order to help wetlands to maintain a certain area, we should predict the natural area of wetlands first. In this paper, we used Momoge wetland in Jilin Province of China as the object of study to predict wetland area. First, we analyzed the main impact factors and their different influence on the area of Momoge wetland. We used the method of fuzzy reasoning method, which could well adapt to the highly nonlinear characteristics of multi-factor prediction. The results showed that the prediction accuracy of the fuzzy reasoning method is better than that of the multiple regression analysis method. The fuzzy reasoning method can be used in the studies of multi-index nonlinear prediction, evaluation, and classification in many engineering fields.
2017, 15(2):122-126.
Abstract:
In the process of urban construction, it is necessary for water supply channels to strengthen their ability to withstand sudden pollution accidents. Taking the water supply channels of Haikou city in the lower reaches of Nandu River as an example, we established a hydrodynamic and water quality model and used it to analyze the arrival time and impact duration of pollutants. We proposed that check sluices and emergency channels should be built ahead of the Longtang intake to guide the pollution clouds generated from accidents in the upper reaches into the emergency channel. According to the simulation results of the hydrodynamic and water quality model, this measure could reduce effectively the amount of pollutants in Nandu River and prevent sudden water pollution accidents from affecting the water supply of the channels.
In the process of urban construction, it is necessary for water supply channels to strengthen their ability to withstand sudden pollution accidents. Taking the water supply channels of Haikou city in the lower reaches of Nandu River as an example, we established a hydrodynamic and water quality model and used it to analyze the arrival time and impact duration of pollutants. We proposed that check sluices and emergency channels should be built ahead of the Longtang intake to guide the pollution clouds generated from accidents in the upper reaches into the emergency channel. According to the simulation results of the hydrodynamic and water quality model, this measure could reduce effectively the amount of pollutants in Nandu River and prevent sudden water pollution accidents from affecting the water supply of the channels.
2017, 15(2):127-131.
Abstract:
Smoothed particle hydrodynamics (SPH) method is a meshless particle method based on the Lagrangian method, and has been applied in many fields of science and engineering. In this paper, the SPH method was used to simulate the overflow of a two-dimensional broad-crested weir, and parallel computation was carried out to improve the efficiency. The simulation data were compared with the experimental data. The results showed that the SPH method can simulate the hydraulic parameters such as the flow regime, water drops, recirculation zone and water jump phenomenon of the two-dimensional broad-crested weir. We can obtain the flow velocity distribution on the section from the data. This study proved that the SPH method can be used to simulate the flow velocity distribution and water surface profile.
Smoothed particle hydrodynamics (SPH) method is a meshless particle method based on the Lagrangian method, and has been applied in many fields of science and engineering. In this paper, the SPH method was used to simulate the overflow of a two-dimensional broad-crested weir, and parallel computation was carried out to improve the efficiency. The simulation data were compared with the experimental data. The results showed that the SPH method can simulate the hydraulic parameters such as the flow regime, water drops, recirculation zone and water jump phenomenon of the two-dimensional broad-crested weir. We can obtain the flow velocity distribution on the section from the data. This study proved that the SPH method can be used to simulate the flow velocity distribution and water surface profile.
20 3D numerical investigation of bridge pier-scour development using a dynamic-mesh updating technique
2017, 15(2):132-137.
Abstract:
Based on the dynamic-mesh updating technique and user-defined function of FLUENT software, we realized the three-dimensional dynamic simulation of local pier scour. We established the numerical model using the Melville classical scour test as a prototype. The river bed was set as the main moving boundary. When the instantaneous shear stress of the bed surface was larger than the critical shear stress, the position of the node moved down, shown as scour. Van Rijn’s transport function was introduced to control the velocity of each node in the river bed. The numerical results were in good agreement with the experimental results regarding the flow field structure, occurrence and development process of scour holes, and shape of scour holes. The simulated depth of scour holes was slightly smaller than the experimental results, with an error of about 13%. The main reason for the error was the inability of the URANS models to effectively reflect the turbulent fluctuations at the leading edge of blunt piers.
Based on the dynamic-mesh updating technique and user-defined function of FLUENT software, we realized the three-dimensional dynamic simulation of local pier scour. We established the numerical model using the Melville classical scour test as a prototype. The river bed was set as the main moving boundary. When the instantaneous shear stress of the bed surface was larger than the critical shear stress, the position of the node moved down, shown as scour. Van Rijn’s transport function was introduced to control the velocity of each node in the river bed. The numerical results were in good agreement with the experimental results regarding the flow field structure, occurrence and development process of scour holes, and shape of scour holes. The simulated depth of scour holes was slightly smaller than the experimental results, with an error of about 13%. The main reason for the error was the inability of the URANS models to effectively reflect the turbulent fluctuations at the leading edge of blunt piers.
2017, 15(2):138-142.
Abstract:
The calculation and analysis of transient process is important to the security of hydropower station. Based on the one-dimensional unsteady flow theory, a numerical model of “long diversion open channel + pressure forebay + pressure conduit+ units” for the system was established for a special hydropower station with long diversion open channel. According to boundary conditions, it calculated the transient flow of pressure pipe using the characteristic method and calculated the transient flow of open channel using Preissmann implicit difference method. It analyzed the change of water level and discharge in channel and forebay in different conditions. It decided the reasonable approach to increasing load due to the low velocity of wave spreading. It ensured the lowest level of open channel and forebay and economic benefits. This gives significant reference to analogous engineering.
The calculation and analysis of transient process is important to the security of hydropower station. Based on the one-dimensional unsteady flow theory, a numerical model of “long diversion open channel + pressure forebay + pressure conduit+ units” for the system was established for a special hydropower station with long diversion open channel. According to boundary conditions, it calculated the transient flow of pressure pipe using the characteristic method and calculated the transient flow of open channel using Preissmann implicit difference method. It analyzed the change of water level and discharge in channel and forebay in different conditions. It decided the reasonable approach to increasing load due to the low velocity of wave spreading. It ensured the lowest level of open channel and forebay and economic benefits. This gives significant reference to analogous engineering.
2017, 15(2):143-148.
Abstract:
Sand mining in a river is a huge threat to the safety of nearby river-crossing structures. To determine how far a sand mining project would threaten the nearby river-crossing structures, we firstly reviewed the standards about sand mining. Based on theoretical research and physical experiments on sand pit migration and its impact on riverbed, this paper proposed an empirical formula to determine the safe distance for upstream sand mining from river-crossing structures. Based on hydraulic parameters, characteristics of sediment, and the size and geometry of the pit, the proposed formula can calculate the migration of sand pit, and then determine the safe distance. This formula was verified using the observation data in an actual river and the results were acceptable. Finally, the formula was applied to determine the safe distance for the inverted siphon project in Anyang River as a case study, and to provide a reasonable guide for sand mining activities along the river.
Sand mining in a river is a huge threat to the safety of nearby river-crossing structures. To determine how far a sand mining project would threaten the nearby river-crossing structures, we firstly reviewed the standards about sand mining. Based on theoretical research and physical experiments on sand pit migration and its impact on riverbed, this paper proposed an empirical formula to determine the safe distance for upstream sand mining from river-crossing structures. Based on hydraulic parameters, characteristics of sediment, and the size and geometry of the pit, the proposed formula can calculate the migration of sand pit, and then determine the safe distance. This formula was verified using the observation data in an actual river and the results were acceptable. Finally, the formula was applied to determine the safe distance for the inverted siphon project in Anyang River as a case study, and to provide a reasonable guide for sand mining activities along the river.
2017, 15(2):149-155.
Abstract:
The drainage effect of deep wells influences engineering design. According to the surveyed geological data, the finite element model for seepage analysis was established. Based on the fixed finite element method for unsaturated seepage analysis, the unsteady seepage field of deep well drainage was calculated. Then comparison was conducted between the numerical calculation and the test data. The results showed that the deep well drainage method was effective, and the permeability of foundation soil had a great influence on the seepage field. We suggest that appropriate well depth and well spacing should be adopted so as to ensure the effect of deep well drainage. The results can provide reference for drainage measures on similar clay foundations.
The drainage effect of deep wells influences engineering design. According to the surveyed geological data, the finite element model for seepage analysis was established. Based on the fixed finite element method for unsaturated seepage analysis, the unsteady seepage field of deep well drainage was calculated. Then comparison was conducted between the numerical calculation and the test data. The results showed that the deep well drainage method was effective, and the permeability of foundation soil had a great influence on the seepage field. We suggest that appropriate well depth and well spacing should be adopted so as to ensure the effect of deep well drainage. The results can provide reference for drainage measures on similar clay foundations.
2017, 15(2):156-162.
Abstract:
The suspended bars in the stilling basin can improve the energy dissipation effect of the stilling basin but are eroded and damaged by water currents. To study the effect of water currents on the stability of the suspended bars, we obtained the optimal layout patterns of the single- or double-layer suspended bars. We conducted washout tests with the optimal layout patterns. At the same time, we used the RNG k-ε double-equation turbulence model to do numerical simulation computation and compared the test results. We found that when the design value of per-unit-width discharge q0=21.43 l/s, the optimal layout pattern of single-layer suspended bars is 11 bars with a bar spacing of 5.5 cm and a height of 10 cm. In this model, the first bar was scoured seriously, with its stability greatly compromised. The optimal layout pattern of double-layer bars is 11 bars with a bar spacing of 12 cm and a height of 4 cm. In this model, the first bar and the bottom layer were scoured seriously with their stability greatly compromised. The study results can be used to improve the structure of the suspended bars.
The suspended bars in the stilling basin can improve the energy dissipation effect of the stilling basin but are eroded and damaged by water currents. To study the effect of water currents on the stability of the suspended bars, we obtained the optimal layout patterns of the single- or double-layer suspended bars. We conducted washout tests with the optimal layout patterns. At the same time, we used the RNG k-ε double-equation turbulence model to do numerical simulation computation and compared the test results. We found that when the design value of per-unit-width discharge q0=21.43 l/s, the optimal layout pattern of single-layer suspended bars is 11 bars with a bar spacing of 5.5 cm and a height of 10 cm. In this model, the first bar was scoured seriously, with its stability greatly compromised. The optimal layout pattern of double-layer bars is 11 bars with a bar spacing of 12 cm and a height of 4 cm. In this model, the first bar and the bottom layer were scoured seriously with their stability greatly compromised. The study results can be used to improve the structure of the suspended bars.
2017, 15(2):163-169.
Abstract:
Regional land subsidence is one of the city diseases which many cities in the world must be facing. Excessive exploitation of groundwater is the most common reason for urban land subsidence. Land subsidence is particularly significant due to groundwater exploitation in Beijing. Based on a method combining qualitative and quantitative analysis, a contrastive analysis of spatial-temporal evolution between land subsidence and groundwater exploitation during 60 years was carried out in the paper in order to understand the new characteristics of land subsidence distribution with new conditions of groundwater exploitation and promote implementation of Beijing Land Subsidence Control Program (2013-2020). The results showed that it was quite consistent in the temporal patterns of formation and development between land subsidence and groundwater exploitation; the spatial-temporal distribution of land subsidence center area was highly correlated with the changes of groundwater depression cone; the primary subsidence layers gradually shifted to deeper formation (with depth more than 100 m) along with the increase of the mining depth of groundwater. These findings will provide the basis for decision-making of land subsidence control.
Regional land subsidence is one of the city diseases which many cities in the world must be facing. Excessive exploitation of groundwater is the most common reason for urban land subsidence. Land subsidence is particularly significant due to groundwater exploitation in Beijing. Based on a method combining qualitative and quantitative analysis, a contrastive analysis of spatial-temporal evolution between land subsidence and groundwater exploitation during 60 years was carried out in the paper in order to understand the new characteristics of land subsidence distribution with new conditions of groundwater exploitation and promote implementation of Beijing Land Subsidence Control Program (2013-2020). The results showed that it was quite consistent in the temporal patterns of formation and development between land subsidence and groundwater exploitation; the spatial-temporal distribution of land subsidence center area was highly correlated with the changes of groundwater depression cone; the primary subsidence layers gradually shifted to deeper formation (with depth more than 100 m) along with the increase of the mining depth of groundwater. These findings will provide the basis for decision-making of land subsidence control.
2017, 15(2):170-175.
Abstract:
Landslide soil strength parameters are the key parameters in the landslide evaluation and management engineering design. Currently a common value-selection method is profile inversion. The result of single profile inversion is multiple combinations of parameters. The inversion of two or more profiles would present a mathematically overdetermined problem with no unique solution. Based on the optimization theory and method, when the equation set of multi-profile inversion parameters had an overdetermined problem, this paper transformed the inverse problem into a direct problem, constructed an objective function, indirectly inversed the parameters using the one-by-one correction method, and obtained the optimal values of the parameters. Thus, it obtained the strength parameters that reflected the characteristics of sliding soil and were suitable for each profile. In this paper, with Huangjiaoshu landslide as an example, we combined the results of indoor experiments and inversion analysis to determine the range of parameters values, and used one-by-one correction method to optimize parameters values. The optimized parameters were c=9.76kpa, φ=6.81°, and they tallied with the deformation state when verified with each profile. This paper can provide reference for landslide soil parameters values selection in landslide prevention engineering. But the method does not apply to all cases; it is only feasible when a set of comprehensive parameters are needed.
Landslide soil strength parameters are the key parameters in the landslide evaluation and management engineering design. Currently a common value-selection method is profile inversion. The result of single profile inversion is multiple combinations of parameters. The inversion of two or more profiles would present a mathematically overdetermined problem with no unique solution. Based on the optimization theory and method, when the equation set of multi-profile inversion parameters had an overdetermined problem, this paper transformed the inverse problem into a direct problem, constructed an objective function, indirectly inversed the parameters using the one-by-one correction method, and obtained the optimal values of the parameters. Thus, it obtained the strength parameters that reflected the characteristics of sliding soil and were suitable for each profile. In this paper, with Huangjiaoshu landslide as an example, we combined the results of indoor experiments and inversion analysis to determine the range of parameters values, and used one-by-one correction method to optimize parameters values. The optimized parameters were c=9.76kpa, φ=6.81°, and they tallied with the deformation state when verified with each profile. This paper can provide reference for landslide soil parameters values selection in landslide prevention engineering. But the method does not apply to all cases; it is only feasible when a set of comprehensive parameters are needed.
27 Numerical analysis of characteristics of internal flow field in automatic screen filter with torpedo
2017, 15(2):176-184.
Abstract:
The water flow field in automatic screen filter with torpedo was numerically simulated at different flow rates via the porous jump model and Realizable k-ε model in FLUENT. The results showed that the calculated head loss was highly consistent with the test result. Thus, the mathematical model was highly accurate and reliable. The comparison among the calculation results at different flow rates showed that the velocity and pressure distribution patterns were the same at different flow rates within the filter. The greater the flow, the greater the head loss, and the greater the velocity and pressure difference between the inner and outer sides of the screen. The velocity and pressure distribution were not uniform in the filter. Therefore, the structure of the filter awaits further optimization.
The water flow field in automatic screen filter with torpedo was numerically simulated at different flow rates via the porous jump model and Realizable k-ε model in FLUENT. The results showed that the calculated head loss was highly consistent with the test result. Thus, the mathematical model was highly accurate and reliable. The comparison among the calculation results at different flow rates showed that the velocity and pressure distribution patterns were the same at different flow rates within the filter. The greater the flow, the greater the head loss, and the greater the velocity and pressure difference between the inner and outer sides of the screen. The velocity and pressure distribution were not uniform in the filter. Therefore, the structure of the filter awaits further optimization.
2017, 15(2):185-191.
Abstract:
Reasonable soil parameters directly affect the displacement and internal force calculation results of the supporting structure in foundation pit design. Especially the proportional coefficient m of horizontal resistance has the most pronounced influence on the displacement of the supporting structure. Based on an engineering case of foundation excavation, the characters of materials and process of foundation excavation were simulated by the plane finite difference method, so that the horizontal displacement of the supporting structure for the excavation was simulated and calculated. Through analysis of the influence of soil parameters on the horizontal displacement of the supporting structure, it was determined that Young's modulus was the parameter to be obtained for the back-analysis of displacement. The objective function between measured displacement and simulated displacement was built, and Young's modulus of each soil layer was obtained through back-analysis. The relationship between m value and Young's modulus was derived by the elastic foundation beam method, and thereby m value of each soil layer was obtained. The research results provided a certain theoretical basis for reasonable determination of design parameters of foundation pit, and has important practical significance for the effective control of the displacement and deformation of foundation pits.
Reasonable soil parameters directly affect the displacement and internal force calculation results of the supporting structure in foundation pit design. Especially the proportional coefficient m of horizontal resistance has the most pronounced influence on the displacement of the supporting structure. Based on an engineering case of foundation excavation, the characters of materials and process of foundation excavation were simulated by the plane finite difference method, so that the horizontal displacement of the supporting structure for the excavation was simulated and calculated. Through analysis of the influence of soil parameters on the horizontal displacement of the supporting structure, it was determined that Young's modulus was the parameter to be obtained for the back-analysis of displacement. The objective function between measured displacement and simulated displacement was built, and Young's modulus of each soil layer was obtained through back-analysis. The relationship between m value and Young's modulus was derived by the elastic foundation beam method, and thereby m value of each soil layer was obtained. The research results provided a certain theoretical basis for reasonable determination of design parameters of foundation pit, and has important practical significance for the effective control of the displacement and deformation of foundation pits.
2017, 15(2):192-197.
Abstract:
Real-time and accurate measurement of soil parameters，such as soil water, soil electrical conductivity and pH, is the premise to realize precise irrigation. Laboratory calibration of several instruments for measurement of soil parameters now used in research and agricultural production was conducted in this paper to test the reliability of these instrument test results. The results showed that the instruments of TDR and soil electric conductivity meter were simple operation and the test results showed high precision. When measuring soil water, the test results of pH meter and three-unity showed better accuracy and high reliability, the two instruments also had the feature of simple operation. But suitable soil water controlled value should be determined according to the properties of the soil and the crop or vegetable when using them. The instrument of three-unity was not suitable for using in pH measurement. The instrument of four-unity showed low reliability when measuring soil water and was not suitable for use in agricultural production. The content of soil electrical conductivity and soil water showed negative correlation, soil electric conductivity showed the tendency of decline with the increase of soil water. The results of this paper can provide reference for the choice of instruments for measuring soil environmental parameters in agricultural production.
Real-time and accurate measurement of soil parameters，such as soil water, soil electrical conductivity and pH, is the premise to realize precise irrigation. Laboratory calibration of several instruments for measurement of soil parameters now used in research and agricultural production was conducted in this paper to test the reliability of these instrument test results. The results showed that the instruments of TDR and soil electric conductivity meter were simple operation and the test results showed high precision. When measuring soil water, the test results of pH meter and three-unity showed better accuracy and high reliability, the two instruments also had the feature of simple operation. But suitable soil water controlled value should be determined according to the properties of the soil and the crop or vegetable when using them. The instrument of three-unity was not suitable for using in pH measurement. The instrument of four-unity showed low reliability when measuring soil water and was not suitable for use in agricultural production. The content of soil electrical conductivity and soil water showed negative correlation, soil electric conductivity showed the tendency of decline with the increase of soil water. The results of this paper can provide reference for the choice of instruments for measuring soil environmental parameters in agricultural production.
2017, 15(2):198-202.
Abstract:
In view of the advantages and disadvantages of Hyperbola model and Logistic model, we put forward the Hyperbola-Logistic model. The model integrated the advantages of both single forecasting models so as to achieve high accuracy. Based on the observation data of the foundation settlement at power plants, the Hyperbola-Logistic superposition model was used to predict the ground settlement, and the results were compared with the results of the single settlement forecasting models. The results showed that, compared with the forecasting results of the two single forecasting models, the superposition model reduced system error and improved the accuracy of prediction. The fitting results were reliable, and can be applied to the foundation settlement prediction of power plants. The new model is feasible, and is an effective method to analyze and predict foundation settlement.
In view of the advantages and disadvantages of Hyperbola model and Logistic model, we put forward the Hyperbola-Logistic model. The model integrated the advantages of both single forecasting models so as to achieve high accuracy. Based on the observation data of the foundation settlement at power plants, the Hyperbola-Logistic superposition model was used to predict the ground settlement, and the results were compared with the results of the single settlement forecasting models. The results showed that, compared with the forecasting results of the two single forecasting models, the superposition model reduced system error and improved the accuracy of prediction. The fitting results were reliable, and can be applied to the foundation settlement prediction of power plants. The new model is feasible, and is an effective method to analyze and predict foundation settlement.
2017, 15(2):203-208.
Abstract:
In order to further study water source heat pump projects, we generally introduced a water source heat pump project and its water drawing and draining scheme, calculated the water intake in summer conditions, normal winter conditions, and extreme winter conditions, built a 3D diagram of the water drawing and draining part, used CFX to numerically simulate the effects of water drawing and draining on the river in the three conditions, and analyzed the energy conservation effect of water source heat pump. Results showed that in the 3 conditions, the draining streams have no effect on the temperature field around the upstream water inlet in River A. Compared with the basic temperature of River A, the average water temperature of River B before joining River A fluctuates by less than 1℃, meaning the water draining has no effect on River A. The energy conservation effect of the project is prominent. The study on the effect of water drawing and draining by water source heat pumps on the temperature field of rivers and the energy conservation effect of the project can provide reference for the design and optimization of water source heat pump projects.
In order to further study water source heat pump projects, we generally introduced a water source heat pump project and its water drawing and draining scheme, calculated the water intake in summer conditions, normal winter conditions, and extreme winter conditions, built a 3D diagram of the water drawing and draining part, used CFX to numerically simulate the effects of water drawing and draining on the river in the three conditions, and analyzed the energy conservation effect of water source heat pump. Results showed that in the 3 conditions, the draining streams have no effect on the temperature field around the upstream water inlet in River A. Compared with the basic temperature of River A, the average water temperature of River B before joining River A fluctuates by less than 1℃, meaning the water draining has no effect on River A. The energy conservation effect of the project is prominent. The study on the effect of water drawing and draining by water source heat pumps on the temperature field of rivers and the energy conservation effect of the project can provide reference for the design and optimization of water source heat pump projects.
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