Volume 19,Issue 2,2021 Table of Contents
2021, 19(2):209-216.
Abstract:
Highquality development of the Yellow River basin is the main goal and task for Yellow River′s national strategy.The Henan section of the Yellow River is a key economic and cultural zone in the Yellow River basin (YRB).To clarify the spatial research scope in the Henan section of the Yellow River and conduct indepth research on the optimization of highquality development paths is of great strategic significance for the future growth of Henan Province and YRB. To clarify and define the research scope of the Henan section of the Yellow River and provide basic support for subsequent research work,the spatial research scope is divided into five subregions based on different research needs,namely: mainstream flow area,drainage area,water supply area,strategic implementation area,and all administrative regions.The mainstream flow area in the Henan section of the Yellow River refers to the area composed of all the municipal administrative districts in Henan Province that flow through the mainstream of the Yellow River,with a total area of 57,900 km2.The drainage area of the Henan section is 36,200 km2 within the jurisdiction of Henan Province.The water supply area is 104,000 km2 of the Henan section of the Yellow River,which refers to the area composed of all municipal administrative districts that use Yellow River water as a water supply source in Henan Province.The strategic implementation area in the Henan section refers to all municipallevel administrative areas affected by the Yellow River national strategy within Henan Province,covering 15 cities with a total area of 106,600 km2.Based on this zoning,15 cities in Henan Province are included in the Yellow River national strategy,and Nanyang,Xinyang,and Zhumadian are included in the development strategy of Yangtze River economic belt strategy.All administrative regions refer to all municipallevel administrative regions throughout Henan Province,iIncluding 18 cities in the province,with a total area of 167,000 km2. Based on an indepth understanding of highquality development,under the guidance of important ideas such as sustainable development,harmony between humans and water,and ecological civilization,a research framework for selecting highquality development paths for the Henan section of the Yellow River is constructed.[JP2]The tasks that need to be achieved to research the optimization of highquality development paths include safe supply of resources,ecological health and livability,orderly[JP] economic growth,social harmony and stability,and advanced cultural leadership.The key issues that need to be resolved include ①resourcesecologyeconomysociety harmonious balance theory and quantification; ②identification of key constraints on highquality development; ③optimization method for highquality development paths based on harmonious balance theory; ④construction of a harmonious regulation model for highquality development.The core technologies that need to be broken through include: ① Identification technology for the key constraints of highquality development of the resourceecologicaleconomicsocial composite system development; ②dynamic simulationoptimization technology for the optimization of highquality development path;③highquality development of multidimensional critical harmony control technology based on the harmonious balance theory. Four key contents of the research on the optimization of highquality development paths include: (1) resourceecologicaleconomicsocial composite system harmonious balance theory and quantitative research methods,including: ①the harmonious balance relationship between highquality development and resourceecologicaleconomicsocial;②resourceecologicaleconomicsocial harmonious balance model and theoretical framework system;③harmonious balance theory application rules and plan formulation cycle path method; ④harmonious balance discrimination criterion and quantitative evaluation method.(2) Identification of key constraints and countermeasures for highquality development of the Henan section of the Yellow River,including: ①analysis of the mutual feedback relationship between resourceecologicaleconomicsocial composite system;②identification of key factors restricting the highquality development based on system identification technology;③responding strategies for key constraints on highquality development under changing circumstances.(3) highquality development path selection and strategic layout in the Henan section of the Yellow River based on the harmonious balance theory,including:①analysis of the highquality development path; ②optimization of highquality development paths based on the harmonious balance theory; ③highquality development strategy layout.(4) the highquality development harmonious regulation model and application of the Henan section of the Yellow River,including: ①guidelines and indicators for the harmonious regulation of highquality development;②highquality development resourceecologicaleconomicsocial harmony goal and quantification; ③construction,application test and effect evaluation of highquality development regulation model.
Highquality development of the Yellow River basin is the main goal and task for Yellow River′s national strategy.The Henan section of the Yellow River is a key economic and cultural zone in the Yellow River basin (YRB).To clarify the spatial research scope in the Henan section of the Yellow River and conduct indepth research on the optimization of highquality development paths is of great strategic significance for the future growth of Henan Province and YRB. To clarify and define the research scope of the Henan section of the Yellow River and provide basic support for subsequent research work,the spatial research scope is divided into five subregions based on different research needs,namely: mainstream flow area,drainage area,water supply area,strategic implementation area,and all administrative regions.The mainstream flow area in the Henan section of the Yellow River refers to the area composed of all the municipal administrative districts in Henan Province that flow through the mainstream of the Yellow River,with a total area of 57,900 km2.The drainage area of the Henan section is 36,200 km2 within the jurisdiction of Henan Province.The water supply area is 104,000 km2 of the Henan section of the Yellow River,which refers to the area composed of all municipal administrative districts that use Yellow River water as a water supply source in Henan Province.The strategic implementation area in the Henan section refers to all municipallevel administrative areas affected by the Yellow River national strategy within Henan Province,covering 15 cities with a total area of 106,600 km2.Based on this zoning,15 cities in Henan Province are included in the Yellow River national strategy,and Nanyang,Xinyang,and Zhumadian are included in the development strategy of Yangtze River economic belt strategy.All administrative regions refer to all municipallevel administrative regions throughout Henan Province,iIncluding 18 cities in the province,with a total area of 167,000 km2. Based on an indepth understanding of highquality development,under the guidance of important ideas such as sustainable development,harmony between humans and water,and ecological civilization,a research framework for selecting highquality development paths for the Henan section of the Yellow River is constructed.[JP2]The tasks that need to be achieved to research the optimization of highquality development paths include safe supply of resources,ecological health and livability,orderly[JP] economic growth,social harmony and stability,and advanced cultural leadership.The key issues that need to be resolved include ①resourcesecologyeconomysociety harmonious balance theory and quantification; ②identification of key constraints on highquality development; ③optimization method for highquality development paths based on harmonious balance theory; ④construction of a harmonious regulation model for highquality development.The core technologies that need to be broken through include: ① Identification technology for the key constraints of highquality development of the resourceecologicaleconomicsocial composite system development; ②dynamic simulationoptimization technology for the optimization of highquality development path;③highquality development of multidimensional critical harmony control technology based on the harmonious balance theory. Four key contents of the research on the optimization of highquality development paths include: (1) resourceecologicaleconomicsocial composite system harmonious balance theory and quantitative research methods,including: ①the harmonious balance relationship between highquality development and resourceecologicaleconomicsocial;②resourceecologicaleconomicsocial harmonious balance model and theoretical framework system;③harmonious balance theory application rules and plan formulation cycle path method; ④harmonious balance discrimination criterion and quantitative evaluation method.(2) Identification of key constraints and countermeasures for highquality development of the Henan section of the Yellow River,including: ①analysis of the mutual feedback relationship between resourceecologicaleconomicsocial composite system;②identification of key factors restricting the highquality development based on system identification technology;③responding strategies for key constraints on highquality development under changing circumstances.(3) highquality development path selection and strategic layout in the Henan section of the Yellow River based on the harmonious balance theory,including:①analysis of the highquality development path; ②optimization of highquality development paths based on the harmonious balance theory; ③highquality development strategy layout.(4) the highquality development harmonious regulation model and application of the Henan section of the Yellow River,including: ①guidelines and indicators for the harmonious regulation of highquality development;②highquality development resourceecologicaleconomicsocial harmony goal and quantification; ③construction,application test and effect evaluation of highquality development regulation model.
2021, 19(2):217-225,236.
Abstract:
The balanced coordination relationship between water resources and the three systems including population,economy and society,and the ecological environment is a key criterion to achieve "spatial equilibrium",which mainly includes the sustainable use of water resources,the highquality development of economy and society,and the virtuous cycle of ecological environment.Many scholars focus on the theory of "spatial equilibrium" for water resources.However,few studies are investigating the comprehensive evaluation of "spatial equilibrium" state for regions or basins due to the lack of unified evaluation standard.Accurately evaluating the spatial equilibrium state for the Yellow River basin is of great significance to recognize the natural law,ecological and economic law of the Yellow River,and formulating scientific and reasonable water resources management measures based on local conditions. The development and utilization of water resources were evaluated in the main stream and 13 tributaries for Yellow River.The carrying capacity of water resources and water environment for 70 prefecturelevel administrative regions was also evaluated.The evaluation index system of "spatial equilibrium" is constructed based on 14 indexes,deriving from five aspects,including the endowment and supply of water resources,the economy and society,the food and energy,the water resources carrying capacity,and the water environment carrying conditions.The state of "spatial equilibrium" is evaluated through the multiindex comprehensive evaluation method. In terms of the utilization degree of water resources in the main streams and tributaries,62% of the Yellow River basin areas are in the state of "high" or "extremely high" utilization degree.The "extremely high" utilization degree state covers an area of 56,000 km2,accounting for nearly 7% of the whole basin,which is mainly distributed in Shanxi Province (for the middle reaches of the Yellow River) and Shandong Province (for the lower reaches).The following region was considered to have a lower degree of utilization,including the water sources area in the main stream above Longyang Gorge Reservoir,Taohe River,Daxia River,and Datong River in Gannan,and the Wuding River,covering an area of about 213,000 km2,accounting for 27% of the basin area.The northern Shaanxi and western Shanxi areas are of "moderate" state,accounting for 11% of the whole basin area,because the local surface water is quite difficult to use under their special topography condition.For the water resources carrying capacity condition,among the 70 prefecturelevel administrative regions in the Yellow River basin,13 regions are in the state of "seriously overloaded",accounting for 18.6%,and 19 regions are elevated as "overloaded" (accounting for 271%).Besides, there are 10 "critical" and 28 "not overloaded" regions,accounting for 14.3% and 40.0%,respectively.From water environment perspective,there are 35 prefecturelevel administrative regions (half of the whole numbers) of 8 provinces in the state of "seriously overloaded" or "overloaded",among which 12 regions are "seriously overloaded",and 23 regions are "overloaded".Besides,there are 5 and 30 regions in the state of "critical" and "not overloaded",accounting for 7.1% and 42.9%,respectively.According to the comprehensive evaluation,the Yellow River basin is generally in a state of spatial "imbalance",and the areas of spatial "extremely imbalance" are mainly distributed in the NingxiaInner Mongolia Reach of the upper reaches of the Yellow River,FenWei River plain of the middle reaches,and the beaches of the lower reaches. The water resources in Yellow River basin are generally in a state of spatial "imbalance".To improve the degree of "spatial equilibrium" of the "imbalance" areas,corresponding measures should be taken(insisting the problemoriented and demandoriented strategy),according to the different equilibrium problems and causes in different regions,and the coordination between water and the systems of economic,society,and ecological environment must improve.In the NingxiaInner Mongolia Reach,we must enroll the "waterdetermineland" route,meanwhile take series of water saving measures for agricultural.In the FenWei River plain,the key route is to coordinate the relationship among water,energy and food,such as optimizing the economic structure,comprehensively treating the areas of groundwater overextraction,and strictly restricting the emission of river pollutants.In the downstream areas,the scheme of replacing the water diversion beyond the basin should be seriously considered in combination with the followup SouthtoNorth Water Transfer Project and the water price policy.
The balanced coordination relationship between water resources and the three systems including population,economy and society,and the ecological environment is a key criterion to achieve "spatial equilibrium",which mainly includes the sustainable use of water resources,the highquality development of economy and society,and the virtuous cycle of ecological environment.Many scholars focus on the theory of "spatial equilibrium" for water resources.However,few studies are investigating the comprehensive evaluation of "spatial equilibrium" state for regions or basins due to the lack of unified evaluation standard.Accurately evaluating the spatial equilibrium state for the Yellow River basin is of great significance to recognize the natural law,ecological and economic law of the Yellow River,and formulating scientific and reasonable water resources management measures based on local conditions. The development and utilization of water resources were evaluated in the main stream and 13 tributaries for Yellow River.The carrying capacity of water resources and water environment for 70 prefecturelevel administrative regions was also evaluated.The evaluation index system of "spatial equilibrium" is constructed based on 14 indexes,deriving from five aspects,including the endowment and supply of water resources,the economy and society,the food and energy,the water resources carrying capacity,and the water environment carrying conditions.The state of "spatial equilibrium" is evaluated through the multiindex comprehensive evaluation method. In terms of the utilization degree of water resources in the main streams and tributaries,62% of the Yellow River basin areas are in the state of "high" or "extremely high" utilization degree.The "extremely high" utilization degree state covers an area of 56,000 km2,accounting for nearly 7% of the whole basin,which is mainly distributed in Shanxi Province (for the middle reaches of the Yellow River) and Shandong Province (for the lower reaches).The following region was considered to have a lower degree of utilization,including the water sources area in the main stream above Longyang Gorge Reservoir,Taohe River,Daxia River,and Datong River in Gannan,and the Wuding River,covering an area of about 213,000 km2,accounting for 27% of the basin area.The northern Shaanxi and western Shanxi areas are of "moderate" state,accounting for 11% of the whole basin area,because the local surface water is quite difficult to use under their special topography condition.For the water resources carrying capacity condition,among the 70 prefecturelevel administrative regions in the Yellow River basin,13 regions are in the state of "seriously overloaded",accounting for 18.6%,and 19 regions are elevated as "overloaded" (accounting for 271%).Besides, there are 10 "critical" and 28 "not overloaded" regions,accounting for 14.3% and 40.0%,respectively.From water environment perspective,there are 35 prefecturelevel administrative regions (half of the whole numbers) of 8 provinces in the state of "seriously overloaded" or "overloaded",among which 12 regions are "seriously overloaded",and 23 regions are "overloaded".Besides,there are 5 and 30 regions in the state of "critical" and "not overloaded",accounting for 7.1% and 42.9%,respectively.According to the comprehensive evaluation,the Yellow River basin is generally in a state of spatial "imbalance",and the areas of spatial "extremely imbalance" are mainly distributed in the NingxiaInner Mongolia Reach of the upper reaches of the Yellow River,FenWei River plain of the middle reaches,and the beaches of the lower reaches. The water resources in Yellow River basin are generally in a state of spatial "imbalance".To improve the degree of "spatial equilibrium" of the "imbalance" areas,corresponding measures should be taken(insisting the problemoriented and demandoriented strategy),according to the different equilibrium problems and causes in different regions,and the coordination between water and the systems of economic,society,and ecological environment must improve.In the NingxiaInner Mongolia Reach,we must enroll the "waterdetermineland" route,meanwhile take series of water saving measures for agricultural.In the FenWei River plain,the key route is to coordinate the relationship among water,energy and food,such as optimizing the economic structure,comprehensively treating the areas of groundwater overextraction,and strictly restricting the emission of river pollutants.In the downstream areas,the scheme of replacing the water diversion beyond the basin should be seriously considered in combination with the followup SouthtoNorth Water Transfer Project and the water price policy.
XING Yincong
,
LIN Yixue
,
LI Yanzhong
,
LIANG Kang
,
LIU Changming
,
DU Shenwen
,
LI Xianqing
,
ZHANG Mi
,
YUN Yue′e
2021, 19(2):226-236.
Abstract:
The error in the precipitation estimation will bring great uncertainty to hydrological process simulation and climate change prediction research.A series of remote sensing precipitation products have provided the possibility to accurately estimate largescale precipitation.However,the remote sensing products from different sources are quite inconsistent.It is urgent to obtain highresolution,highprecision precipitation data sets through multisource data fusion technology,with the purpose of reducing the error of single remotesensing precipitation products and improve the accuracy of precipitation estimation.The middle reaches of the Yellow River is located in the semiarid and semihumid transition zone of China,which is a crucial area for the ecological environment restoration projects.Precipitation is the main water resources for this region,while an accurate precipitation estimation is of great singificance to the sustainable development of the regional ecological environment and the stability of economic life. Based on the background,the middle reaches of the Yellow River are chosed as the research area,which is extremely sensitive to the climate change and human activities.The methods of ensemble model output statistical (EMOS),quantile mapping (QM),and simple mean to the four productions (MME),while the indexes of four basic statistical indicators of correlation coefficient,relative deviation,root mean square error,and KlingGupta coefficient,as well as three category indexes of detection rate (POD),false alarm rate (FAR),and critical success index (CSI),to quantitatively evaluate the performance of four precipitation products (CHIRPS,CMORPH,PERSIANNCDR and TMPA 3B42),and then compare and analyze the performance of different data fusion data sets. The results show that:(1) The fusion data set of EMOS can significantly improve the index of bias,root mean square error,and KGE,with the values of -3.4%,13.1 mm,γKGE=0.233,respectively,compared with MME and individual product.The stations with better performance of QM were mainly located in the southern region,while the better performance for EMOS was observed in the eastern region.(2) Both the QM and EMOS methods have significantly improved the performance of POD,with the average values reaching 0.44 and 0.38,respectively,but the spatial distribution POD calucated from EMOS data set is more concentrated.The critical success index (CSI) of QM and EMOS methods reached 0.30 and 0.28,respectively,increasing approximately 12% compared with MME.The QM method did not significantly improve the POD,but the POD is doubled with a value of 0.33 by the EMOS method. In summary,the data fusion results obtained by the EMOS method have significant advantages over other methods,and the performance improvements are spatially different.The precipitation data set obtained by the EMOS method significantly improves the detection ability for moderate and heavy rain,indicating better performance for detecting the highintensity precipitation events.The precipitation data set fused with EMOS can well provide data support for the study of the relationship between extreme precipitation and sediment transport in typical ecological restoration areas in the middle reaches of the Yellow River,and provide a scientific basis for the rapid restoration of vegetation on precipitation and other climate feedback.
The error in the precipitation estimation will bring great uncertainty to hydrological process simulation and climate change prediction research.A series of remote sensing precipitation products have provided the possibility to accurately estimate largescale precipitation.However,the remote sensing products from different sources are quite inconsistent.It is urgent to obtain highresolution,highprecision precipitation data sets through multisource data fusion technology,with the purpose of reducing the error of single remotesensing precipitation products and improve the accuracy of precipitation estimation.The middle reaches of the Yellow River is located in the semiarid and semihumid transition zone of China,which is a crucial area for the ecological environment restoration projects.Precipitation is the main water resources for this region,while an accurate precipitation estimation is of great singificance to the sustainable development of the regional ecological environment and the stability of economic life. Based on the background,the middle reaches of the Yellow River are chosed as the research area,which is extremely sensitive to the climate change and human activities.The methods of ensemble model output statistical (EMOS),quantile mapping (QM),and simple mean to the four productions (MME),while the indexes of four basic statistical indicators of correlation coefficient,relative deviation,root mean square error,and KlingGupta coefficient,as well as three category indexes of detection rate (POD),false alarm rate (FAR),and critical success index (CSI),to quantitatively evaluate the performance of four precipitation products (CHIRPS,CMORPH,PERSIANNCDR and TMPA 3B42),and then compare and analyze the performance of different data fusion data sets. The results show that:(1) The fusion data set of EMOS can significantly improve the index of bias,root mean square error,and KGE,with the values of -3.4%,13.1 mm,γKGE=0.233,respectively,compared with MME and individual product.The stations with better performance of QM were mainly located in the southern region,while the better performance for EMOS was observed in the eastern region.(2) Both the QM and EMOS methods have significantly improved the performance of POD,with the average values reaching 0.44 and 0.38,respectively,but the spatial distribution POD calucated from EMOS data set is more concentrated.The critical success index (CSI) of QM and EMOS methods reached 0.30 and 0.28,respectively,increasing approximately 12% compared with MME.The QM method did not significantly improve the POD,but the POD is doubled with a value of 0.33 by the EMOS method. In summary,the data fusion results obtained by the EMOS method have significant advantages over other methods,and the performance improvements are spatially different.The precipitation data set obtained by the EMOS method significantly improves the detection ability for moderate and heavy rain,indicating better performance for detecting the highintensity precipitation events.The precipitation data set fused with EMOS can well provide data support for the study of the relationship between extreme precipitation and sediment transport in typical ecological restoration areas in the middle reaches of the Yellow River,and provide a scientific basis for the rapid restoration of vegetation on precipitation and other climate feedback.
2021, 19(2):237-245.
Abstract:
In recent years,under the dual influence of global warming and intensified human social activities,the hydrological cycle process has been greatly affected,and even changed the spatial and temporal distribution characteristics of hydrological elements,directly affecting the regional water balance,and inducing natural disasters such as rainstorm,flood,heat wave,drought and so on.Therefore,the study of hydrological cycle process under changing environment has become one of the hot issues in the field of water science.Precipitation,as the most direct driving factor of urban waterlogging,is also the main component of hydrological cycle.The study on precipitation characteristics can reveal the characteristics of regional drought and waterlogging disasters more accurately. Moving average method is a relatively simple trend fitting method,which can be regarded as a kind of low pass filter.After moving average,the period shorter than the sliding length in the data series is greatly weakened,and the development trend of the data series can be more easily expressed.MannKendall nonparametric test method is a widely used trend analysis and test method for meteorological data series such as precipitation and temperature.Sen′s Slope estimation method:If there is a trend of change in a certain series of data,Sen′s Slope estimation method can be used to estimate the size of the trend to represent the average trend of change in the series of data,which is usually used in combination with MannKendall method.Morlet continuous complex wavelet transform analysis can reveal a variety of time series change period,so as to qualitatively evaluate the future trend. The results showed that :(1) Annual precipitation increased at a rate of 8.23 mm/(10 a),and showed an alternating period of abundance and drying,with a maximum main period of 10 a.(2) The precipitation was mainly concentrated in summer,accounting for 64.5% of the annual precipitation,and the proportion of winter precipitation was the smallest,accounting for 3.4% of the annual precipitation.The precipitation in spring,summer and winter showed no significant increase trend,and the precipitation in autumn showed no significant decrease trend.(3) The interannual,spring and summer variation of precipitation is mainly affected by the change of precipitation intensity;The variation in autumn and winter is mainly affected by the variation of precipitation frequency. (1) The annual precipitation in Jinan [JP2]showed an increasing trend from 1972 to 2016,increasing at a rate of 8.23 mm/(10 a),[JP]but the increasing trend was not significant,and it showed an alternating cycle of abundant and dry.The main period of interannual variation was 23 a,and it had three subcycles:5 a,10 a and 15 a.The maximum annual precipitation occurred in 1990 (939.9 mm),and the minimum annual precipitation occurred in 1989 (374.1 mm),with the maximum being 2.51 times of the minimum.(2) From 1972 to 2016,the precipitation in spring,summer and winter of Jinan showed no significant increase trend,and the precipitation in autumn showed no significant decrease trend.Moreover,the precipitation was mainly concentrated in summer,accounting for 645% of the annual precipitation,and the precipitation in winter was the least,accounting for less than 4% of the annual precipitation.The variation range of summer precipitation is the largest,followed by spring and autumn,and the variation range of winter precipitation is the least.(3) The interannual variability of precipitation in Jinan is mainly affected by precipitation intensity,and the increase of precipitation intensity is the main reason for the increase of precipitation;The increase of precipitation in spring and summer is also caused by the increase of precipitation intensity.On the other hand,the decrease of precipitation in autumn and the increase of precipitation in winter are mainly affected by the decrease and increase of precipitation frequency (i.e.,precipitation days).
In recent years,under the dual influence of global warming and intensified human social activities,the hydrological cycle process has been greatly affected,and even changed the spatial and temporal distribution characteristics of hydrological elements,directly affecting the regional water balance,and inducing natural disasters such as rainstorm,flood,heat wave,drought and so on.Therefore,the study of hydrological cycle process under changing environment has become one of the hot issues in the field of water science.Precipitation,as the most direct driving factor of urban waterlogging,is also the main component of hydrological cycle.The study on precipitation characteristics can reveal the characteristics of regional drought and waterlogging disasters more accurately. Moving average method is a relatively simple trend fitting method,which can be regarded as a kind of low pass filter.After moving average,the period shorter than the sliding length in the data series is greatly weakened,and the development trend of the data series can be more easily expressed.MannKendall nonparametric test method is a widely used trend analysis and test method for meteorological data series such as precipitation and temperature.Sen′s Slope estimation method:If there is a trend of change in a certain series of data,Sen′s Slope estimation method can be used to estimate the size of the trend to represent the average trend of change in the series of data,which is usually used in combination with MannKendall method.Morlet continuous complex wavelet transform analysis can reveal a variety of time series change period,so as to qualitatively evaluate the future trend. The results showed that :(1) Annual precipitation increased at a rate of 8.23 mm/(10 a),and showed an alternating period of abundance and drying,with a maximum main period of 10 a.(2) The precipitation was mainly concentrated in summer,accounting for 64.5% of the annual precipitation,and the proportion of winter precipitation was the smallest,accounting for 3.4% of the annual precipitation.The precipitation in spring,summer and winter showed no significant increase trend,and the precipitation in autumn showed no significant decrease trend.(3) The interannual,spring and summer variation of precipitation is mainly affected by the change of precipitation intensity;The variation in autumn and winter is mainly affected by the variation of precipitation frequency. (1) The annual precipitation in Jinan [JP2]showed an increasing trend from 1972 to 2016,increasing at a rate of 8.23 mm/(10 a),[JP]but the increasing trend was not significant,and it showed an alternating cycle of abundant and dry.The main period of interannual variation was 23 a,and it had three subcycles:5 a,10 a and 15 a.The maximum annual precipitation occurred in 1990 (939.9 mm),and the minimum annual precipitation occurred in 1989 (374.1 mm),with the maximum being 2.51 times of the minimum.(2) From 1972 to 2016,the precipitation in spring,summer and winter of Jinan showed no significant increase trend,and the precipitation in autumn showed no significant decrease trend.Moreover,the precipitation was mainly concentrated in summer,accounting for 645% of the annual precipitation,and the precipitation in winter was the least,accounting for less than 4% of the annual precipitation.The variation range of summer precipitation is the largest,followed by spring and autumn,and the variation range of winter precipitation is the least.(3) The interannual variability of precipitation in Jinan is mainly affected by precipitation intensity,and the increase of precipitation intensity is the main reason for the increase of precipitation;The increase of precipitation in spring and summer is also caused by the increase of precipitation intensity.On the other hand,the decrease of precipitation in autumn and the increase of precipitation in winter are mainly affected by the decrease and increase of precipitation frequency (i.e.,precipitation days).
2021, 19(2):246-254.
Abstract:
The impact of climate change human activities has affected the consistency of historical hydrologic data,which has gradually turned these areas into datadeficient areas or areas without data.The problem of Prediction in Ungauged Basins (PUB) has been a research hotspot in the world.The PUB problem in small watersheds in hilly areas is one of the difficulties.In recent years,some hydrological models based on the physical characteristics of watersheds have been applied to hydrological simulations in the areas lacking data or without data.This reduced the dependence of hydrological simulations on historical data,and provided a good opportunity to study the mechanism of runoff generation and convergence in areas without data. An SCS model is used based on constant term revision and a Nash unit line based on topography and geomorphology characteristics.Three typical small watersheds in hilly areas of Jiangsu Province were selected for application research,aiming to explore and solve the problem of runoff yield and confluence and flood forecasting of small watersheds in hilly areas in the shortage of data.The improvement of the SCS model mainly includes the following three points.The revision of the SCS model mainly uses the previous impact rainfall Pa instead of the previous 5 d rainfall total in the original model to determine the degree of soil moisture in the previous period and increase the classification of the number of runoff CN.Combining the reestimated previous soil moisture degree,linear interpolation is used to increase the classification of the number of runoff curves,reduce the level of CN value,and then revise the CN value table;establish an empirical relationship with the CN value reflecting the topographical features.According to the small watershed data with measured rainfall and runoff data,the S value in the SCN model is calculated,and then the constant term in the SCN relationship is revised.using the rich observed rainfall data in small watershed,figure out the S value in the SCS model,and then revised the constant term of the SCS model. Taking 3 small watersheds in Jiangsu Province as the research area,the SCS runoff generation model was improved in terms of determining the degree of soil moisture in the early stage,increasing the CN value classification and revising the constant term.Finally,the constant term of the SCS runoff generation model was determined as 160.The revised SCS runoff model was combined with the Nash confluence model based on topographic and geomorphic parameters to construct the SCSNash hydrological model of the hilly small watersheds.The test results showed that the SCSNash model had good applicability in flood simulation and forecasting,and the calculation accuracy was slightly improved. The results showed that the SCSNash hydrological model had certain precision.Especially for the simulation and forecast of the peak discharge,the relative errors of 8 out of 9 floods are less than 20 %.Considering that the predicting accuracy of the peak discharge is more important,the SCSNash hydrological model have some applicability in the flood forecast of small watershed in the hilly areas of Jiangsu Province.Due to the lack of hydrological data in small watersheds in hilly areas,the study did not collect sufficient hydrological data.Although the research results have been used for reference in the flood forecast of small watersheds in Jiangsu Province,the conclusion is preliminary,and a more comprehensive conclusion needs further study.
The impact of climate change human activities has affected the consistency of historical hydrologic data,which has gradually turned these areas into datadeficient areas or areas without data.The problem of Prediction in Ungauged Basins (PUB) has been a research hotspot in the world.The PUB problem in small watersheds in hilly areas is one of the difficulties.In recent years,some hydrological models based on the physical characteristics of watersheds have been applied to hydrological simulations in the areas lacking data or without data.This reduced the dependence of hydrological simulations on historical data,and provided a good opportunity to study the mechanism of runoff generation and convergence in areas without data. An SCS model is used based on constant term revision and a Nash unit line based on topography and geomorphology characteristics.Three typical small watersheds in hilly areas of Jiangsu Province were selected for application research,aiming to explore and solve the problem of runoff yield and confluence and flood forecasting of small watersheds in hilly areas in the shortage of data.The improvement of the SCS model mainly includes the following three points.The revision of the SCS model mainly uses the previous impact rainfall Pa instead of the previous 5 d rainfall total in the original model to determine the degree of soil moisture in the previous period and increase the classification of the number of runoff CN.Combining the reestimated previous soil moisture degree,linear interpolation is used to increase the classification of the number of runoff curves,reduce the level of CN value,and then revise the CN value table;establish an empirical relationship with the CN value reflecting the topographical features.According to the small watershed data with measured rainfall and runoff data,the S value in the SCN model is calculated,and then the constant term in the SCN relationship is revised.using the rich observed rainfall data in small watershed,figure out the S value in the SCS model,and then revised the constant term of the SCS model. Taking 3 small watersheds in Jiangsu Province as the research area,the SCS runoff generation model was improved in terms of determining the degree of soil moisture in the early stage,increasing the CN value classification and revising the constant term.Finally,the constant term of the SCS runoff generation model was determined as 160.The revised SCS runoff model was combined with the Nash confluence model based on topographic and geomorphic parameters to construct the SCSNash hydrological model of the hilly small watersheds.The test results showed that the SCSNash model had good applicability in flood simulation and forecasting,and the calculation accuracy was slightly improved. The results showed that the SCSNash hydrological model had certain precision.Especially for the simulation and forecast of the peak discharge,the relative errors of 8 out of 9 floods are less than 20 %.Considering that the predicting accuracy of the peak discharge is more important,the SCSNash hydrological model have some applicability in the flood forecast of small watershed in the hilly areas of Jiangsu Province.Due to the lack of hydrological data in small watersheds in hilly areas,the study did not collect sufficient hydrological data.Although the research results have been used for reference in the flood forecast of small watersheds in Jiangsu Province,the conclusion is preliminary,and a more comprehensive conclusion needs further study.
2021, 19(2):255-262.
Abstract:
Water resources are basic natural resources and strategic economic resources.Water resources utilization efficiency reflects the development and utilization of water resources,and improving water resources utilization efficiency can promote the sustainable development of economy and the benign operation of economysocietyecological system.The evaluation of water resources utilization efficiency is the premise and foundation of the efficient and rational utilization of water resources.At present,the evaluation of water resources utilization efficiency lacks further deconstruction of efficiency value and systematic analysis from two angles of relative efficiency and absolute efficiency.Scientific and systematic evaluation of regional water resources utilization efficiency can deeply understand the situation and level of water consumption in the region,and formulate targeted measures for the utilizationof water resources. Henan Province was selected as the typical study area.The labor,fixed asset investment and water consumption of 18 cities in Henan Province from 2009 to 2018 were taken as input indexes,while GDP and sewage discharge were taken as output indexes,the inputoriented SBMDEA model was used to study the relative water resources utilization efficiency of cities in Henan Province,and Malmquist index was used to analyze the absolute water resources utilization efficiency in different cities from two aspects of improvements in efficiency and technological advances.On this basis,the DEA values of each city were taken as the dependent variable,and the per capita water use,per capita GDP,the proportion of primary industry,the proportion of secondary industry,agricultural water consumption and the proportion of agricultural water consumption were taken as independent variables,the crosssectional Tobit regression model was used to analyze the main factors affecting the water resources utilization efficiency. From the analysis of relative efficiency,the overall water resources utilization efficiency of Henan Province is not high,which shows a stable and slow downward trend overall;Zhengzhou is at the forefront of water resources utilization efficiency in Henan Province,and water resources utilization efficiency is the best due to the rapid economic and social development;The central area of Henan Province is close to the provincial capital Zhengzhou,which affects its production technology level;Because of the abundant water conservancy,water resourcesutilization efficiency of the western part of Henan Province is better than that in other areas;the gap of water resources utilization efficiency between regions is gradually decreasing with the passage of time.From the analysis of absolute efficiency,at present,the water resources allocation in Henan Province has been improved,but the application level of water resources technology needs to be strengthened;the technical efficiency index of Henan Province fluctuated steadily over the years,while the technical progress index fluctuated greatly,and the trend highly coincided with the Malmquist index;the average annual growth rate of water resources utilization efficiency in Henan Province is 2.7%,and the average annual growth rate of change index of technological progress is 3.1%;the improvement of technology level is the main factor for the increase of water resources utilization efficiency in Henan Province.The analysis results of the influencing factors of water consumption efficiency show that,the proportion of primary industry and agricultural water are the main factors affecting the water resources utilization efficiency in Henan Province.The increase of the proportion of primary industry will improve the water resources utilization efficiency,while the increase of the proportion of agricultural water will reduce the water resources utilization efficiency . In addition to Zhengzhou,which has fully achieved the DEA effectiveness,other cities still have the insufficiency of water resources utilization efficiency.The space imbalance requires us to take measures according to local conditions and take corresponding measures for different regions.Technological progress is the main factor affecting the growth of water resources utilization efficiency in Henan Province.In the future,the use of hightech products should be increased to improve water resources utilization efficiency.As a large agricultural province,agricultural water consumption is an important link of water consumption in Henan Province.In the future,it is necessary to continue to promote watersaving agricultural production,adjust industrial production structure,and introduce industrial watersaving technology to improve water resources utilization efficiency.
Water resources are basic natural resources and strategic economic resources.Water resources utilization efficiency reflects the development and utilization of water resources,and improving water resources utilization efficiency can promote the sustainable development of economy and the benign operation of economysocietyecological system.The evaluation of water resources utilization efficiency is the premise and foundation of the efficient and rational utilization of water resources.At present,the evaluation of water resources utilization efficiency lacks further deconstruction of efficiency value and systematic analysis from two angles of relative efficiency and absolute efficiency.Scientific and systematic evaluation of regional water resources utilization efficiency can deeply understand the situation and level of water consumption in the region,and formulate targeted measures for the utilizationof water resources. Henan Province was selected as the typical study area.The labor,fixed asset investment and water consumption of 18 cities in Henan Province from 2009 to 2018 were taken as input indexes,while GDP and sewage discharge were taken as output indexes,the inputoriented SBMDEA model was used to study the relative water resources utilization efficiency of cities in Henan Province,and Malmquist index was used to analyze the absolute water resources utilization efficiency in different cities from two aspects of improvements in efficiency and technological advances.On this basis,the DEA values of each city were taken as the dependent variable,and the per capita water use,per capita GDP,the proportion of primary industry,the proportion of secondary industry,agricultural water consumption and the proportion of agricultural water consumption were taken as independent variables,the crosssectional Tobit regression model was used to analyze the main factors affecting the water resources utilization efficiency. From the analysis of relative efficiency,the overall water resources utilization efficiency of Henan Province is not high,which shows a stable and slow downward trend overall;Zhengzhou is at the forefront of water resources utilization efficiency in Henan Province,and water resources utilization efficiency is the best due to the rapid economic and social development;The central area of Henan Province is close to the provincial capital Zhengzhou,which affects its production technology level;Because of the abundant water conservancy,water resourcesutilization efficiency of the western part of Henan Province is better than that in other areas;the gap of water resources utilization efficiency between regions is gradually decreasing with the passage of time.From the analysis of absolute efficiency,at present,the water resources allocation in Henan Province has been improved,but the application level of water resources technology needs to be strengthened;the technical efficiency index of Henan Province fluctuated steadily over the years,while the technical progress index fluctuated greatly,and the trend highly coincided with the Malmquist index;the average annual growth rate of water resources utilization efficiency in Henan Province is 2.7%,and the average annual growth rate of change index of technological progress is 3.1%;the improvement of technology level is the main factor for the increase of water resources utilization efficiency in Henan Province.The analysis results of the influencing factors of water consumption efficiency show that,the proportion of primary industry and agricultural water are the main factors affecting the water resources utilization efficiency in Henan Province.The increase of the proportion of primary industry will improve the water resources utilization efficiency,while the increase of the proportion of agricultural water will reduce the water resources utilization efficiency . In addition to Zhengzhou,which has fully achieved the DEA effectiveness,other cities still have the insufficiency of water resources utilization efficiency.The space imbalance requires us to take measures according to local conditions and take corresponding measures for different regions.Technological progress is the main factor affecting the growth of water resources utilization efficiency in Henan Province.In the future,the use of hightech products should be increased to improve water resources utilization efficiency.As a large agricultural province,agricultural water consumption is an important link of water consumption in Henan Province.In the future,it is necessary to continue to promote watersaving agricultural production,adjust industrial production structure,and introduce industrial watersaving technology to improve water resources utilization efficiency.
2021, 19(2):263-272.
Abstract:
With increasingly prominent global environmental problems,climate change research,including water surface evaporation,has become one of the current international scientific research hotspots and has received extensive attention from the international community.Northsouth transition zone is a sensitive area in response to global climate change,as well as the main water source for the midline of the SouthtoNorth Water Diversion and a key area for the western development.However,few researches focus on the water surface evaporation of the entire northsouth transition zone. The methods such as climate tendency rate,MannKendall (M-K) trend test and grey correlation analysis,as well as R/S analysis are mainly employed. The annual average water surface evaporation in China′s northsouth transition zone shows a significant upward trend,with a climate tendency rate of 19.3 mm/(10 a).There was an abrupt point in water surface evaporation around 1994.Before 1994,water surface evaporation showed a decreasing trend,with an annual average water surface evaporation of 807.5 mm.After that,water surface evaporation began to increase,showing an upward trend.From 1994 to 2017，the average water surface evaporation had increased by 50.0 mm compared with that from 1980 to 1993.Summer accounted for the highest water surface evaporation,followed by spring,autumn and winter.The climate tendency rates of each season were sorted by summer,spring,winter and autumn in terms of seasonal change trends,and the average water surface evaporation in summer showed a significant upward trend.The abrupt points occurred in each season were around 2004 in spring,around 1990 in summer,around 1985 in autumn,while there was no change in winter.Before the abrupt point,spring,summer and autumn all had a downward trend;after that,they all had an upward trend.There were obvious spatial differences in water surface evaporation in the northsouth transition zone,with the highest overall performance in the east,the second in the west and the lowest in the middle.The range of annual average water surface evaporation is 565.6 mm to 1 138.5 mm.Among them,the lowest annual average water surface evaporation was Dujiangyan,in the southwest of Sichuan Province,and the highest was Wudu in Gansu Province.The climate tendency rate of water surface evaporation was lower in the middle and northeast of the study area and was higher in the northwest,southwest and southeast.The lowest and highest values [JP2]were -54.0 mm/(10 a) at Sanmenxia Station and 66.1 mm/(10 a)[JP] at Songpan Station,respectively.The correlation between annual average water surface evaporation and various meteorological factors were analyzed.The order of correlation between each meteorological factor and water surface evaporation in the northsouth transition zone is sunshine hours,average temperature,average wind speed and relative humidity,respectively.Among them,the correlation between sunshine hour and water surface evaporation,and the correlation between average temperature and water surface evaporation are both greater than 0.8.However,the changing trend of sunshine hour in the northsouth transition zone was not prominent during the study period.Therefore,it can be concluded that the main reason for increasing water surface evaporation in the north-south transition zone is the increment of average temperature.The R/S analysis method was used to analyze the annual average water surface evaporation during the study period,and results showed that the water surface evaporation in the northsouth transition zone might continue the previous trend for a period of time.Therefore,it can be predicted that the water surface evaporation in the northsouth transition zone may continue to show an upward trend in the future. (1) From the perspective of temporal variation,the annual average water surface evaporation in the northsouth transition zone showed a significant upward trend,an abrupt point occurred around 1994,and the water surface evaporation increased significantly in summer.(2) From the perspective of spatial variation,the climatic tendency rate of water surface evaporation was lower in the middle and northeast of the study area,and higher in other areas.(3) The main reason for increasing water surface evaporation in the northsouth transition zone was the increase of average temperature.In the future,the water surface evaporation in the northsouth transition zone may continue to show an upward trend.
With increasingly prominent global environmental problems,climate change research,including water surface evaporation,has become one of the current international scientific research hotspots and has received extensive attention from the international community.Northsouth transition zone is a sensitive area in response to global climate change,as well as the main water source for the midline of the SouthtoNorth Water Diversion and a key area for the western development.However,few researches focus on the water surface evaporation of the entire northsouth transition zone. The methods such as climate tendency rate,MannKendall (M-K) trend test and grey correlation analysis,as well as R/S analysis are mainly employed. The annual average water surface evaporation in China′s northsouth transition zone shows a significant upward trend,with a climate tendency rate of 19.3 mm/(10 a).There was an abrupt point in water surface evaporation around 1994.Before 1994,water surface evaporation showed a decreasing trend,with an annual average water surface evaporation of 807.5 mm.After that,water surface evaporation began to increase,showing an upward trend.From 1994 to 2017，the average water surface evaporation had increased by 50.0 mm compared with that from 1980 to 1993.Summer accounted for the highest water surface evaporation,followed by spring,autumn and winter.The climate tendency rates of each season were sorted by summer,spring,winter and autumn in terms of seasonal change trends,and the average water surface evaporation in summer showed a significant upward trend.The abrupt points occurred in each season were around 2004 in spring,around 1990 in summer,around 1985 in autumn,while there was no change in winter.Before the abrupt point,spring,summer and autumn all had a downward trend;after that,they all had an upward trend.There were obvious spatial differences in water surface evaporation in the northsouth transition zone,with the highest overall performance in the east,the second in the west and the lowest in the middle.The range of annual average water surface evaporation is 565.6 mm to 1 138.5 mm.Among them,the lowest annual average water surface evaporation was Dujiangyan,in the southwest of Sichuan Province,and the highest was Wudu in Gansu Province.The climate tendency rate of water surface evaporation was lower in the middle and northeast of the study area and was higher in the northwest,southwest and southeast.The lowest and highest values [JP2]were -54.0 mm/(10 a) at Sanmenxia Station and 66.1 mm/(10 a)[JP] at Songpan Station,respectively.The correlation between annual average water surface evaporation and various meteorological factors were analyzed.The order of correlation between each meteorological factor and water surface evaporation in the northsouth transition zone is sunshine hours,average temperature,average wind speed and relative humidity,respectively.Among them,the correlation between sunshine hour and water surface evaporation,and the correlation between average temperature and water surface evaporation are both greater than 0.8.However,the changing trend of sunshine hour in the northsouth transition zone was not prominent during the study period.Therefore,it can be concluded that the main reason for increasing water surface evaporation in the north-south transition zone is the increment of average temperature.The R/S analysis method was used to analyze the annual average water surface evaporation during the study period,and results showed that the water surface evaporation in the northsouth transition zone might continue the previous trend for a period of time.Therefore,it can be predicted that the water surface evaporation in the northsouth transition zone may continue to show an upward trend in the future. (1) From the perspective of temporal variation,the annual average water surface evaporation in the northsouth transition zone showed a significant upward trend,an abrupt point occurred around 1994,and the water surface evaporation increased significantly in summer.(2) From the perspective of spatial variation,the climatic tendency rate of water surface evaporation was lower in the middle and northeast of the study area,and higher in other areas.(3) The main reason for increasing water surface evaporation in the northsouth transition zone was the increase of average temperature.In the future,the water surface evaporation in the northsouth transition zone may continue to show an upward trend.
2021, 19(2):273-280.
Abstract:
The multi-regional LMDI (Logarithmic Mean Divisia Index) decomposition model is developed to analyze the driving effect of domestic water consumption changes caused by the demographic and urbanization process of 21 cities in Guangdong Province,according to the perspective of spatial and temporal changes. The LMDI method (LMDI-I) was used to perform additive decomposition on the changes of domestic water use.Based on the traditional method,factors such as population distribution and urbanrural structure were incorporated into the factor decomposition model to explore the driving mechanism of each factor on the change of total domestic water consumption. The results show that: (1) The total domestic water consumption in Guangdong increased steadily,and urban domestic water consumption has increased significantly with an average annual rate of 1.4%.Since the process of new urbanization,the domestic water consumption in rural households dropped and per capita domestic water consumption showed a obviously descending trend.(2) From a regional perspective,the proportion of urban water consumption to domestic water consumption continued to increase,especially in the northern Guangdong with the proportion of urban domestic water consumption increasing from 43.8% in 2009 to 52.8% in 2018.(3) The demographic change factor was the most important positive driving effect leading to the increase in the total domestic water consumption,followed by the population distribution factor and urbanization factor.The water intensity factor was a negative driving effect,delaying the increase in total domestic water consumption.Urbanization factor had a positive impact on the increase in domestic water consumption in the Pearl River Delta urban agglomeration,but had a negative impact on the total domestic water consumption in the other regions. In order to ensure the supply of domestic water during the new urbanization period,it is necessary to further strengthen the overall planning of urban and rural domestic water in various regions,comprehensively consider the differences in regional water scarcity,and innovate the regional water resources differential management mechanism.Meanwhile on the premise of satisfying the demand of the basic water consumption indicators of the region,areas with significant water performance will be allocated [JP2]with more water consumption indicators,which can help generate endogenous power for water saving in the region,and increase the overall carrying capacity of regional water resources to provide a guarantee for the sustainable development of new urbanization.
The multi-regional LMDI (Logarithmic Mean Divisia Index) decomposition model is developed to analyze the driving effect of domestic water consumption changes caused by the demographic and urbanization process of 21 cities in Guangdong Province,according to the perspective of spatial and temporal changes. The LMDI method (LMDI-I) was used to perform additive decomposition on the changes of domestic water use.Based on the traditional method,factors such as population distribution and urbanrural structure were incorporated into the factor decomposition model to explore the driving mechanism of each factor on the change of total domestic water consumption. The results show that: (1) The total domestic water consumption in Guangdong increased steadily,and urban domestic water consumption has increased significantly with an average annual rate of 1.4%.Since the process of new urbanization,the domestic water consumption in rural households dropped and per capita domestic water consumption showed a obviously descending trend.(2) From a regional perspective,the proportion of urban water consumption to domestic water consumption continued to increase,especially in the northern Guangdong with the proportion of urban domestic water consumption increasing from 43.8% in 2009 to 52.8% in 2018.(3) The demographic change factor was the most important positive driving effect leading to the increase in the total domestic water consumption,followed by the population distribution factor and urbanization factor.The water intensity factor was a negative driving effect,delaying the increase in total domestic water consumption.Urbanization factor had a positive impact on the increase in domestic water consumption in the Pearl River Delta urban agglomeration,but had a negative impact on the total domestic water consumption in the other regions. In order to ensure the supply of domestic water during the new urbanization period,it is necessary to further strengthen the overall planning of urban and rural domestic water in various regions,comprehensively consider the differences in regional water scarcity,and innovate the regional water resources differential management mechanism.Meanwhile on the premise of satisfying the demand of the basic water consumption indicators of the region,areas with significant water performance will be allocated [JP2]with more water consumption indicators,which can help generate endogenous power for water saving in the region,and increase the overall carrying capacity of regional water resources to provide a guarantee for the sustainable development of new urbanization.
2021, 19(2):281-292.
Abstract:
Due to climate and topography and there are few water level surface monitoring sites of rivers,lakes and reservoirs,poor continuity of monitoring data and high cost of monitoring,which brings great inconvenience to the scientific assessment of water reserves and the study of the impact of climate change.The development of multitemporal resolution remote sensing technology brings a new opportunity for longterm and rapid monitoring of water level in a large range.The satellite altimeters with low cost,high efficiency,and wide monitoring range allows for extracting the water level which is particularly important for areas where there are lack of in-situ observations. Comparing the methods of traditional radar,synthetic aperture radar(SAR),and other altimeters,this paper reviews advances in applying fullwaveform and wavelet retracking algorithm for various inland water extracting in order to study the merits and demerits of the existing water level extraction method and guide its future application in different scenes,as well puts forward the proposal of improved method for future of satellite altimeters. The results revealed that the subsequent launches of conventional radar altimeter has been gradually improved in spatial and temporal resolution,the measurement precision has been gradually improved,and the time series is longer than before,but it is difficult for the relatively large footprint to monitor small and mediumsized water bodies,and the operation task has basically ended.SAR altimeter is the main satellite altimeter currently in orbit and will be launched，which can enhance the accuracy，reduce the footprint,and make the echo characteristics of water body more obvious.But it has the short operation time and the low data temporal and spatial coverage.It can be combined with the traditional radar altimeter through precision correction to extend the water level time series.Laser altimeter has the absolute advantage of small footprint,high measuring accuracy,more water bodies that can be monitored than most satellite altimeter,and low time resolution.The design of the wide swath altimeter can improve spatial and temporal coverage of data significantly.It can make up for the deficiency of the existing satellite altimeter trajectory only linear monitoring after launch,and promote the application of satellite altimeter water level extraction data in production practice.And it is expected to become the mainstream satellite altimeter in the future.The narrow primary peak retracker and multiple waveform persistent peak retracker have become available for large and mediumsized rivers and lakes with flat terrain.The target waveform retracker based on waveform classification is suitable for large lakes.The bimodal correction algorithm is suitable for lakes with frozen period in cold regions of high latitude.The threshold retracker with multisubwave and multiweight is applicable for large and mediumsized rivers with complex terrain.The TIC algorithm is applicable to detect the level changes in narrow mountain rivers. At present,the water level extraction based on satellite altimeters have limitations in monitoring mountain rivers and,small and mediumsized water bodies due to the complex topographic conditions around the water body and the limitation of the width of the altimeter transit track in the water body.It will be the key development directions in the future to launch new satellite altimeters such as widesweep altimeter,build satellite constellations,improve the continuity and coverage of monitoring data,and develop the high-precision intelligent algorithms.
Due to climate and topography and there are few water level surface monitoring sites of rivers,lakes and reservoirs,poor continuity of monitoring data and high cost of monitoring,which brings great inconvenience to the scientific assessment of water reserves and the study of the impact of climate change.The development of multitemporal resolution remote sensing technology brings a new opportunity for longterm and rapid monitoring of water level in a large range.The satellite altimeters with low cost,high efficiency,and wide monitoring range allows for extracting the water level which is particularly important for areas where there are lack of in-situ observations. Comparing the methods of traditional radar,synthetic aperture radar(SAR),and other altimeters,this paper reviews advances in applying fullwaveform and wavelet retracking algorithm for various inland water extracting in order to study the merits and demerits of the existing water level extraction method and guide its future application in different scenes,as well puts forward the proposal of improved method for future of satellite altimeters. The results revealed that the subsequent launches of conventional radar altimeter has been gradually improved in spatial and temporal resolution,the measurement precision has been gradually improved,and the time series is longer than before,but it is difficult for the relatively large footprint to monitor small and mediumsized water bodies,and the operation task has basically ended.SAR altimeter is the main satellite altimeter currently in orbit and will be launched，which can enhance the accuracy，reduce the footprint,and make the echo characteristics of water body more obvious.But it has the short operation time and the low data temporal and spatial coverage.It can be combined with the traditional radar altimeter through precision correction to extend the water level time series.Laser altimeter has the absolute advantage of small footprint,high measuring accuracy,more water bodies that can be monitored than most satellite altimeter,and low time resolution.The design of the wide swath altimeter can improve spatial and temporal coverage of data significantly.It can make up for the deficiency of the existing satellite altimeter trajectory only linear monitoring after launch,and promote the application of satellite altimeter water level extraction data in production practice.And it is expected to become the mainstream satellite altimeter in the future.The narrow primary peak retracker and multiple waveform persistent peak retracker have become available for large and mediumsized rivers and lakes with flat terrain.The target waveform retracker based on waveform classification is suitable for large lakes.The bimodal correction algorithm is suitable for lakes with frozen period in cold regions of high latitude.The threshold retracker with multisubwave and multiweight is applicable for large and mediumsized rivers with complex terrain.The TIC algorithm is applicable to detect the level changes in narrow mountain rivers. At present,the water level extraction based on satellite altimeters have limitations in monitoring mountain rivers and,small and mediumsized water bodies due to the complex topographic conditions around the water body and the limitation of the width of the altimeter transit track in the water body.It will be the key development directions in the future to launch new satellite altimeters such as widesweep altimeter,build satellite constellations,improve the continuity and coverage of monitoring data,and develop the high-precision intelligent algorithms.
2021, 19(2):293-300.
Abstract:
Using the results of numerical rainfall forecast as the input of the hydrological model can effectively prolong the flood forecast period,and strive more time for flood control.The accuracy of rainfall numerical forecast results used in flood forecast largely determines the accuracy of the hydrological model forecast.Therefore,carrying out evaluation research on the accuracy of rainfall forecast results is of great significance to flood forecasting work.Scholars at home and abroad have carried out researches on the accuracy of rainfall forecasting.However,most of the existing researches focus on the total error of rainfall forecasted by river basins and stations and have not considered the spatial distribution and time history distribution errors of rainfall forecasts. An evaluation method of rainfall forecast accuracy is proposed,which integrates three dimensions of time history,space,and total amount.Because of the different horizontal resolutions of each numerical prediction model,the Kriging interpolation is used to get the grid rainfall value by time,and then the basin area rainfall forecast value is obtained.The measured data from rainfall stations are processed in the same way.Thus,the measured and predicted rainfall of each grid and the whole basin can be obtained.A dimensionless value is selected,and the relative error term is introduced.The relative error of cumulative total rainfall,maximum 1,3,6,12,24 h,and other characteristic periods is comprehensively considered as the order of magnitude evaluation index.To accurately describe the coincidence degree between the predicted rainfall and the measured rainfall spatial distribution,a spatial distribution evaluation method is proposed,which uses the concept of TS score for reference,extends the concept from the field number to the spatial distribution,introduces the concept of tolerance interval,formulates the decision rules of each grid,and obtains the flow domain spatial evaluation index.To evaluate the coincidence degree between the rainfall forecast process and the measured process,the commonly used index "certainty coefficient" of the hydrological forecast is introduced as the time history evaluation index.The comprehensive evaluation index of rainfall is obtained by weighting the above evaluation indexes of magnitude,spatial distribution,and time history distribution. Taking the rainfall data of Yongjiang River basin in Zhejiang Province of China in recent years as an example,the method proposed is used to evaluate a variety of numerical prediction models.The results show that the comprehensive evaluation method proposed can take into account important information such as time history distribution which can not be reflected by TS score and has certain advantages in evaluating the rainfall forecast accuracy of flood control scenarios.At the same time,the rationality of the results is analyzed:under the same level of rainfall,the forecast accuracy of the same numerical forecast model decreases with the extension of the forecast period,and the results conform to the laws of statistics and meteorology.Under the same forecast period,the forecast accuracy of the same numerical forecast model decreases with the increase of rainfall magnitude,and the results conform to the laws of statistics and meteorology.When forecasting light rain and moderate rain,the accuracy of each numerical model has little difference,and the GFS model has a slight advantage in forecasting accuracy.However,with the increase of rainfall magnitude,the rainfall forecasting ability of GFS drops sharply,and its forecasting accuracy is surpassed by GRAPES_MESO and SMSWARMS. The proposed method which integrates three dimensions of magnitude,spatial distribution,and time distribution,can excavate the elements of time distribution that traditional evaluation methods such as TS score do not pay enough attention to.Therefore,this method can better evaluate the accuracy of rainfall forecast based on the demand of flood control scenarios,and can also provide a basis for the fusion application of multiple forecasting models.
Using the results of numerical rainfall forecast as the input of the hydrological model can effectively prolong the flood forecast period,and strive more time for flood control.The accuracy of rainfall numerical forecast results used in flood forecast largely determines the accuracy of the hydrological model forecast.Therefore,carrying out evaluation research on the accuracy of rainfall forecast results is of great significance to flood forecasting work.Scholars at home and abroad have carried out researches on the accuracy of rainfall forecasting.However,most of the existing researches focus on the total error of rainfall forecasted by river basins and stations and have not considered the spatial distribution and time history distribution errors of rainfall forecasts. An evaluation method of rainfall forecast accuracy is proposed,which integrates three dimensions of time history,space,and total amount.Because of the different horizontal resolutions of each numerical prediction model,the Kriging interpolation is used to get the grid rainfall value by time,and then the basin area rainfall forecast value is obtained.The measured data from rainfall stations are processed in the same way.Thus,the measured and predicted rainfall of each grid and the whole basin can be obtained.A dimensionless value is selected,and the relative error term is introduced.The relative error of cumulative total rainfall,maximum 1,3,6,12,24 h,and other characteristic periods is comprehensively considered as the order of magnitude evaluation index.To accurately describe the coincidence degree between the predicted rainfall and the measured rainfall spatial distribution,a spatial distribution evaluation method is proposed,which uses the concept of TS score for reference,extends the concept from the field number to the spatial distribution,introduces the concept of tolerance interval,formulates the decision rules of each grid,and obtains the flow domain spatial evaluation index.To evaluate the coincidence degree between the rainfall forecast process and the measured process,the commonly used index "certainty coefficient" of the hydrological forecast is introduced as the time history evaluation index.The comprehensive evaluation index of rainfall is obtained by weighting the above evaluation indexes of magnitude,spatial distribution,and time history distribution. Taking the rainfall data of Yongjiang River basin in Zhejiang Province of China in recent years as an example,the method proposed is used to evaluate a variety of numerical prediction models.The results show that the comprehensive evaluation method proposed can take into account important information such as time history distribution which can not be reflected by TS score and has certain advantages in evaluating the rainfall forecast accuracy of flood control scenarios.At the same time,the rationality of the results is analyzed:under the same level of rainfall,the forecast accuracy of the same numerical forecast model decreases with the extension of the forecast period,and the results conform to the laws of statistics and meteorology.Under the same forecast period,the forecast accuracy of the same numerical forecast model decreases with the increase of rainfall magnitude,and the results conform to the laws of statistics and meteorology.When forecasting light rain and moderate rain,the accuracy of each numerical model has little difference,and the GFS model has a slight advantage in forecasting accuracy.However,with the increase of rainfall magnitude,the rainfall forecasting ability of GFS drops sharply,and its forecasting accuracy is surpassed by GRAPES_MESO and SMSWARMS. The proposed method which integrates three dimensions of magnitude,spatial distribution,and time distribution,can excavate the elements of time distribution that traditional evaluation methods such as TS score do not pay enough attention to.Therefore,this method can better evaluate the accuracy of rainfall forecast based on the demand of flood control scenarios,and can also provide a basis for the fusion application of multiple forecasting models.
2021, 19(2):301-316,341.
Abstract:
To solve the problem of groundwater pollution along the rivers,a stereoscopic remediation demonstration project is built in a water system in Tongzhou of Beijing，China.The Modflow module and GMS software module RT3D are used to establish a coupling model for groundwater flow and solute transport to predict the effect of groundwater remediation under different conditions.The simulation results show that,the mass concentration of ammonia nitrogen in the groundwater along the river decreased from class V to class III,and locally to class II under the condition of 10,000 m3 of water volume per day.Likewise, the natural infiltration per day is only 2000 m3 under the condition of seepage reduction,which can not form the stereoscopic circulation of groundwater.Ten years later,the mass concentration of ammonia nitrogen in the groundwater along the river is class IV,and locally is class V.The results show that the excavation of the river bed does not use clay to reduce seepage,and the pumping and natural infiltration of polluted groundwater near the river can form a stereoscopic circulation,and the effect of water remediation is significant.
To solve the problem of groundwater pollution along the rivers,a stereoscopic remediation demonstration project is built in a water system in Tongzhou of Beijing，China.The Modflow module and GMS software module RT3D are used to establish a coupling model for groundwater flow and solute transport to predict the effect of groundwater remediation under different conditions.The simulation results show that,the mass concentration of ammonia nitrogen in the groundwater along the river decreased from class V to class III,and locally to class II under the condition of 10,000 m3 of water volume per day.Likewise, the natural infiltration per day is only 2000 m3 under the condition of seepage reduction,which can not form the stereoscopic circulation of groundwater.Ten years later,the mass concentration of ammonia nitrogen in the groundwater along the river is class IV,and locally is class V.The results show that the excavation of the river bed does not use clay to reduce seepage,and the pumping and natural infiltration of polluted groundwater near the river can form a stereoscopic circulation,and the effect of water remediation is significant.
2021, 19(2):317-324,399.
Abstract:
In recent years,with the rapid development of China′s economy and the gradual progress of urbanization,urban industrial and agricultural wastewater,waste liquids,and domestic sewage have been continuously discharged into rivers,which have made the problem of water pollution increasingly worse.A large number of river water bodies have been severely polluted due to eutrophication and water inactivation.The original ecological balance of the water bodies has been destroyed,the ecological environment quality of river water has declined sharply,and even major water pollution accidents that endanger human health have occurred.Quantitative or qualitative evaluation of river water quality elements can provide a scientific basis for subsequent river water pollution control and water environmental protection.Eight evaluation indicators are selected from 14 monitoring sections of the Daqing River from 2014 to 2016 and a combination of improved fuzzy mathematics method and singlefactor evaluation method is used to conduct comprehensive water environment quality evaluation. The traditional fuzzy mathematics method is to construct the fuzzy factor set which is not easy to determine the degree of pros and cons,then establish the evaluation set and the membership function according to the water quality evaluation standard,obtain the weight and the degree of membership to quantify.Finally,the two complex operations are performed to obtain the river [JP2]water quality level based on the principle of maximum membership.This operation is effective in evaluating the general river water environment,but it cannot evaluate the inferior Class V water quality,nor can it obtain water quality indicators that play a major[JP] role in river water quality.Therefore,this research first improves the fuzzy mathematics method and then combines the single-factor evaluation method to obtain the water environment quality evaluation and main pollution indicators of the Daqing River. The results show that in 2014 and 2015,the sections that did not meet the standards of Class V functional zone in the GB-3838[KG-*2]–[KG-*3]2002 Environmental quality standards for surface water were Xingaifang,Wangting,Matou,Jiaozhuang and Anzhou sections,accounting for 35.7% of the monitored sections of that year.In 2016,the sections that did not meet the standards were wharf sections,accounting for 7.14% of the monitored sections of that year.Among them,ammonia nitrogen and total phosphorus were the main pollution factors of the monitored sections.The ammonia nitrogen exceeded the standard by an average of 6.78 times,and the peak appeared at the Wangting section in 2014,which was as high as 10.9 times;the total phosphorus exceeded the standard by an average of 3.51 times,and the peak appeared at the Anzhou section in 2014,which was up to 4.53 times.In addition,in 2014,the chemical oxygen demand of Xingaifang,Matou,and Jiaozhuang sections all slightly exceeded the standard,but their exceeding multiples were all less than 1.2 times.The relative calculated values of dissolved oxygen,permanganate index,five day biochemical oxygen demand,total lead,and petroleum products did not exceed 1.0,all of which met the water environmental quality requirements of Class V functional zones.The water quality of the monitored sections from 2014 to 2015 showed a downward trend,but the water quality category did not change significantly,while the water quality improved significantly in 2016;ammonia nitrogen and total phosphorus were the main influencing factors.Water pollution in the study area is within a controllable range,and subsequent monitoring of pollution sources in key river basins needs to be strengthened to effectively protect the water environment in a timely manner;enterprises or farms that require sewage discharge must be strictly supervised in the river basin and the wastewater must be recycled in a harmless manner.The discharge of domestic sewage and disposal of domestic garbage should be strictly controlled,and direct discharge into rivers should be prohibited. The combination of improved fuzzy mathematics method and singlefactor evaluation method can better solve the problem of fuzzy water pollution that is difficult to quantify.It can not only avoid the influence of human factors and reflect the water environment quality under the joint influence of multiple factors,but also determine the main pollutant categories that affect the water environment quality evaluation results.
In recent years,with the rapid development of China′s economy and the gradual progress of urbanization,urban industrial and agricultural wastewater,waste liquids,and domestic sewage have been continuously discharged into rivers,which have made the problem of water pollution increasingly worse.A large number of river water bodies have been severely polluted due to eutrophication and water inactivation.The original ecological balance of the water bodies has been destroyed,the ecological environment quality of river water has declined sharply,and even major water pollution accidents that endanger human health have occurred.Quantitative or qualitative evaluation of river water quality elements can provide a scientific basis for subsequent river water pollution control and water environmental protection.Eight evaluation indicators are selected from 14 monitoring sections of the Daqing River from 2014 to 2016 and a combination of improved fuzzy mathematics method and singlefactor evaluation method is used to conduct comprehensive water environment quality evaluation. The traditional fuzzy mathematics method is to construct the fuzzy factor set which is not easy to determine the degree of pros and cons,then establish the evaluation set and the membership function according to the water quality evaluation standard,obtain the weight and the degree of membership to quantify.Finally,the two complex operations are performed to obtain the river [JP2]water quality level based on the principle of maximum membership.This operation is effective in evaluating the general river water environment,but it cannot evaluate the inferior Class V water quality,nor can it obtain water quality indicators that play a major[JP] role in river water quality.Therefore,this research first improves the fuzzy mathematics method and then combines the single-factor evaluation method to obtain the water environment quality evaluation and main pollution indicators of the Daqing River. The results show that in 2014 and 2015,the sections that did not meet the standards of Class V functional zone in the GB-3838[KG-*2]–[KG-*3]2002 Environmental quality standards for surface water were Xingaifang,Wangting,Matou,Jiaozhuang and Anzhou sections,accounting for 35.7% of the monitored sections of that year.In 2016,the sections that did not meet the standards were wharf sections,accounting for 7.14% of the monitored sections of that year.Among them,ammonia nitrogen and total phosphorus were the main pollution factors of the monitored sections.The ammonia nitrogen exceeded the standard by an average of 6.78 times,and the peak appeared at the Wangting section in 2014,which was as high as 10.9 times;the total phosphorus exceeded the standard by an average of 3.51 times,and the peak appeared at the Anzhou section in 2014,which was up to 4.53 times.In addition,in 2014,the chemical oxygen demand of Xingaifang,Matou,and Jiaozhuang sections all slightly exceeded the standard,but their exceeding multiples were all less than 1.2 times.The relative calculated values of dissolved oxygen,permanganate index,five day biochemical oxygen demand,total lead,and petroleum products did not exceed 1.0,all of which met the water environmental quality requirements of Class V functional zones.The water quality of the monitored sections from 2014 to 2015 showed a downward trend,but the water quality category did not change significantly,while the water quality improved significantly in 2016;ammonia nitrogen and total phosphorus were the main influencing factors.Water pollution in the study area is within a controllable range,and subsequent monitoring of pollution sources in key river basins needs to be strengthened to effectively protect the water environment in a timely manner;enterprises or farms that require sewage discharge must be strictly supervised in the river basin and the wastewater must be recycled in a harmless manner.The discharge of domestic sewage and disposal of domestic garbage should be strictly controlled,and direct discharge into rivers should be prohibited. The combination of improved fuzzy mathematics method and singlefactor evaluation method can better solve the problem of fuzzy water pollution that is difficult to quantify.It can not only avoid the influence of human factors and reflect the water environment quality under the joint influence of multiple factors,but also determine the main pollutant categories that affect the water environment quality evaluation results.
2021, 19(2):325-333.
Abstract:
The pollution prevention measures are developed based on the causal analysis to improve the water quality of the Winter Olympic Games,to ensure the inflow water quality into Guanting Reservoir (GTR),and to meet the water functional criterion.The water quality of rivers,lakes,and reservoirs is managed delicately. A 2dimensional model MIKE21 coupling with a "nutrients + vegetation" Ecolab module is used to compute the water quality in the downstream of Guishui River (GSR) from Dongdaqiao station to GTR,as well as the tribute of Sanli River (SLR).The pollution load of the main water quality factors on the water quality is analyzed,the phased measures are put forward,and the effect is evaluated. [JP2]The water quality responses by pollution sources,selfpurification ability,wetland vegetation effects,and flow rates change in flood and dry season are the main factors affecting the inflow of GTR.The monitoring data and simulation results in flood and dry periods show that the contribution rate of GSR inflow is large,and ammonia nitrogen,total phosphorus,and total nitrogen contribution rates from GSR inflow to GTR are 18.32%[KG-*5]–[KG-*6]45.76%,9.31%[KG-*5]–[KG-*6]31.17%,and 29.34%[KG-*5]–[KG-*6]67.56%,respectively.The reduction rates of ammonia nitrogen,total phosphorus,and total nitrogen are 44.85%[KG-*5]–[KG-*6]61.29%,51.40%[KG-*5]–[KG-*6]77.92%,and 8.40%[KG-*5]–[KG-*6]23.06%,respectively,in flood season including wetland vegetation action and dry season.Considering the serious water quality problems in the wet season,the construction of riparian wetland and the implementation of sewage interception measures are integrated.The simulation results show that dissolved oxygen,ammonia nitrogen,total phosphorus,and total nitrogen of Guishui River entering Guanting Reservoir are 7.23 mg/L,0.27 mg/L,0.03 mg/L,and 0.62 mg/L,respectively, which reach the class III water quality standard of surface water environment.The dissolved oxygen concentration increases by 2.99%,and the ammonia nitrogen,total phosphorus and total nitrogen concentrations decrease by 19.41%,31.31% and 24.94%,respectively.[JP] The key measures to improve the inflow water quality of GTR and keep good statutes stable are based on comprehensive management of river basin to ensure good water quality at control sections and shutting down the sewage inlet in urban river sections.Meanwhile,rehabilitation of riparian wetlands is helpful to water quality improvement.
The pollution prevention measures are developed based on the causal analysis to improve the water quality of the Winter Olympic Games,to ensure the inflow water quality into Guanting Reservoir (GTR),and to meet the water functional criterion.The water quality of rivers,lakes,and reservoirs is managed delicately. A 2dimensional model MIKE21 coupling with a "nutrients + vegetation" Ecolab module is used to compute the water quality in the downstream of Guishui River (GSR) from Dongdaqiao station to GTR,as well as the tribute of Sanli River (SLR).The pollution load of the main water quality factors on the water quality is analyzed,the phased measures are put forward,and the effect is evaluated. [JP2]The water quality responses by pollution sources,selfpurification ability,wetland vegetation effects,and flow rates change in flood and dry season are the main factors affecting the inflow of GTR.The monitoring data and simulation results in flood and dry periods show that the contribution rate of GSR inflow is large,and ammonia nitrogen,total phosphorus,and total nitrogen contribution rates from GSR inflow to GTR are 18.32%[KG-*5]–[KG-*6]45.76%,9.31%[KG-*5]–[KG-*6]31.17%,and 29.34%[KG-*5]–[KG-*6]67.56%,respectively.The reduction rates of ammonia nitrogen,total phosphorus,and total nitrogen are 44.85%[KG-*5]–[KG-*6]61.29%,51.40%[KG-*5]–[KG-*6]77.92%,and 8.40%[KG-*5]–[KG-*6]23.06%,respectively,in flood season including wetland vegetation action and dry season.Considering the serious water quality problems in the wet season,the construction of riparian wetland and the implementation of sewage interception measures are integrated.The simulation results show that dissolved oxygen,ammonia nitrogen,total phosphorus,and total nitrogen of Guishui River entering Guanting Reservoir are 7.23 mg/L,0.27 mg/L,0.03 mg/L,and 0.62 mg/L,respectively, which reach the class III water quality standard of surface water environment.The dissolved oxygen concentration increases by 2.99%,and the ammonia nitrogen,total phosphorus and total nitrogen concentrations decrease by 19.41%,31.31% and 24.94%,respectively.[JP] The key measures to improve the inflow water quality of GTR and keep good statutes stable are based on comprehensive management of river basin to ensure good water quality at control sections and shutting down the sewage inlet in urban river sections.Meanwhile,rehabilitation of riparian wetlands is helpful to water quality improvement.
2021, 19(2):334-341.
Abstract:
The Qiantang River (Hangzhou Part) is located in the lower reaches of the Yangtze River Economic Belt.It is not only an important source of drinking water,but also related to ecological safety of Hangzhou City and Zhejiang Province.In recent years,due to the rapid social and economic development in the Qiantang River basin,impact of human activities on the water environment has further deepened,and pressure on environmental governance and ecological protection of Qiantang River has significantly increased.Residents in the river basin have further increased their expectations for better water environment,which put forward higher requirements for the water environment management of the Qiantang River (Hangzhou part). To explore the seasonal dynamics of planktonic algae in the Qiantang River (Hangzhou section) and their relationships with environmental factors,and to provide technical support for water environment protection,phytoplankton and environmental factors were monthly monitored in Qiantang River (Hangzhou part) in 2018,including four main sites.Environmental factors mainly include water temperature (T),water pH,turbidity,conductivity,dissolved oxygen (DO),permanganate index (CODMn),ammonia nitrogen mass concentration (NH3-N),total nitrogen mass concentration (TN),and total phosphorus mass concentration (TP). The monthly mass concentration of total chlorophyll of phytoplankton was ranged from 1.74 to 22.86 μg/L,and the monthly chlorophyll mass concentration of cyanobacteria was ranged from 0.02 to 10.82 μg/L.The composition of planktonic algae throughout the year was dominated by cyanobacteria and diatom.The site with highest total chlorophyll mass concentration was Yanlingwu in the four seasons of spring,summer,autumn and winter.The site with the highest mass concentration of cyanobacteria in spring was Jiangjunyan,while the highest mass concentration site in summer,autumn and winter was all Yanlingwu.For all monitoring sites,the highest mass concentration of planktonic algae chlorophyll always occurred in summer.The total chlorophyll mass concentration and the cyanophyll chlorophyll mass concentration showed almost the same seasonal variation trend at Jiangjunyan,indicating that the cyanobacteria had an absolute advantage in composition.It was worth noting that from spring to summer,the chlorophyll mass concentration of cyanobacteria both had increased from the lowest value to the highest value throughout the year at Yanlingwu and Yinzhu.Environmental factors had obvious impacts on the mass concentration of chlorophyll of phytoplankton.There was a significant positive correlation between the annual mass concentration of total chlorophyll of phytoplankton and water temperature.There was a significant positive correlation between the annual mass concentration of cyanobacteria chlorophyll and water temperature.There was a significant negative correlation between the seasonal mass concentration of diatom chlorophyll and total phosphorus. Therefore,the chlorophyll mass concentration of planktonic algae was greatly affected by the physical and chemical factors in Qiantang River (Hangzhou part).Water temperature and total phosphorus were the main environmental factors that affected the seasonal dynamics of planktonic algae.Monitoring and management of different sites all need to focus on different emphasis.It was necessary to implement classified management,linkage monitoring and comparative monitoring of major environmental factors and important points.Preventing and controlling environmental risks as much as possible can help realize the early warning function of monitoring and analysis of plankton algae environment.
The Qiantang River (Hangzhou Part) is located in the lower reaches of the Yangtze River Economic Belt.It is not only an important source of drinking water,but also related to ecological safety of Hangzhou City and Zhejiang Province.In recent years,due to the rapid social and economic development in the Qiantang River basin,impact of human activities on the water environment has further deepened,and pressure on environmental governance and ecological protection of Qiantang River has significantly increased.Residents in the river basin have further increased their expectations for better water environment,which put forward higher requirements for the water environment management of the Qiantang River (Hangzhou part). To explore the seasonal dynamics of planktonic algae in the Qiantang River (Hangzhou section) and their relationships with environmental factors,and to provide technical support for water environment protection,phytoplankton and environmental factors were monthly monitored in Qiantang River (Hangzhou part) in 2018,including four main sites.Environmental factors mainly include water temperature (T),water pH,turbidity,conductivity,dissolved oxygen (DO),permanganate index (CODMn),ammonia nitrogen mass concentration (NH3-N),total nitrogen mass concentration (TN),and total phosphorus mass concentration (TP). The monthly mass concentration of total chlorophyll of phytoplankton was ranged from 1.74 to 22.86 μg/L,and the monthly chlorophyll mass concentration of cyanobacteria was ranged from 0.02 to 10.82 μg/L.The composition of planktonic algae throughout the year was dominated by cyanobacteria and diatom.The site with highest total chlorophyll mass concentration was Yanlingwu in the four seasons of spring,summer,autumn and winter.The site with the highest mass concentration of cyanobacteria in spring was Jiangjunyan,while the highest mass concentration site in summer,autumn and winter was all Yanlingwu.For all monitoring sites,the highest mass concentration of planktonic algae chlorophyll always occurred in summer.The total chlorophyll mass concentration and the cyanophyll chlorophyll mass concentration showed almost the same seasonal variation trend at Jiangjunyan,indicating that the cyanobacteria had an absolute advantage in composition.It was worth noting that from spring to summer,the chlorophyll mass concentration of cyanobacteria both had increased from the lowest value to the highest value throughout the year at Yanlingwu and Yinzhu.Environmental factors had obvious impacts on the mass concentration of chlorophyll of phytoplankton.There was a significant positive correlation between the annual mass concentration of total chlorophyll of phytoplankton and water temperature.There was a significant positive correlation between the annual mass concentration of cyanobacteria chlorophyll and water temperature.There was a significant negative correlation between the seasonal mass concentration of diatom chlorophyll and total phosphorus. Therefore,the chlorophyll mass concentration of planktonic algae was greatly affected by the physical and chemical factors in Qiantang River (Hangzhou part).Water temperature and total phosphorus were the main environmental factors that affected the seasonal dynamics of planktonic algae.Monitoring and management of different sites all need to focus on different emphasis.It was necessary to implement classified management,linkage monitoring and comparative monitoring of major environmental factors and important points.Preventing and controlling environmental risks as much as possible can help realize the early warning function of monitoring and analysis of plankton algae environment.
2021, 19(2):342-351.
Abstract:
Water resources are the basic guarantee of economic development.In the utilization of water resources,industrial water use is more closely related to the economy,and they influence and feedback each other.To reveal their development relationship,the environmental Kuznets curve (EKC) is used for fitting prediction.In the past,researches on the environmental Kuznets curve only focused on the relationship between pollutants and the economy,and there was little pieces of research on water use.However,researches on the industrial water EKC just focus on the discussion of its shape and qualitative analysis and lack quantitative research.Given the shortcomings of the research,Ningxia is selected as the research area,which is deficient in water resources,and has problems such as unreasonable supply and demand structure of industrial water,imperfect management system,low reuse rate,and low utilization rate of unconventional water resources. The Kuznets curve of the industrial water environment is determined by adopting parameters and moving average regression fitting.The central and central Kuznets curve formation mechanism of the industrial water environment in Ningxia is analyzed quantitatively by the Logarithmic Mean Divisia Index (LMDI) to decompose the industrial water use effect into the water use efficiency effect,the industrial structure effect,and the economic scale effect.Finally,the grey prediction model is used to quantitatively predict the development of industrial water EKC in Ningxia in the future,and explore its possible evolution trend in the future. （1）The industrial water consumption in Ningxia increased continuously from 1980 to 1997,with an average annual growth rate of 57%.Water consumption continued to decrease from 1997 to 2004,with an average annual reduction rate of 3.9%.The fluctuation increased from the late period to 2013.It is found that the fitting result of the cubic model is more reasonable than that of a quadratic model,and the fitting degree is higher.From the moving average,it can also be seen that the curve presents a positive N-type.In conclusion,the Kuznets curve of the industrial water environment in Ningxia presents a positive Ntype in the interval from 1980 to 2013.（2）Using LMDI,the influencing factors of industrial water use in Ningxia were decomposed into water use efficiency effect,industrial structure effect,and economic scale effect.Among them,from the perspective of industry,each effect value of the heavy industry is greater than that of the light industry,indicating that heavy industry occupies the dominant position in Ningxia.From the perspective of effect,the effect of water use efficiency has a restraining effect on the increase of water consumption,the effect of economic scale has a promoting effect on the increase of water consumption,but the effect of industrial structure is different.When the sum of the three effects is negative,the water consumption will be saved.Otherwise,the water consumption will increase.It can be concluded that water consumption increased from 1990 to 1997 and from 2004 to 2007,but decreased from 1997 to 2004,showing N-type.Simultaneously,it is found that the change of industrial water consumption in Ningxia is in line with the policies and measures of industrial reform and opening up.（3）According to the prediction results of the grey model and relevant policy guidance,the logarithm of industrial water consumption in Ningxia has a decreasing trend,while the logarithm of per capita industrial GDP has an increasing trend.According to the two predictions,the EKC of industrial water consumption in Ningxia will develop downward in the future. From the above research,it is found that there is a certain relationship between social and economic development and industrial water use.It is reasonable to use the environmental Kuznets curve to fit.Together,it can be seen that the EKC shape of industrial water use is different,which needs to be discussed according to different regions.According to the reason analysis of EKC of industrial water use in Ningxia,the efficiency of industrial water use in Ningxia continues to be flat,so it should be kept continuing to improve the level of industrial water saving,enhance the technical strength,strengthen the ability of water resources monitoring,and promote the development of industrial structure in the direction of optimization and rationality,to further improve the effectiveness of watersaving.It is predicted that the EKC of industrial water use in Ningxia may appear M-type in the future,which indicates whether the curve has periodicity with the change of social economy,that is,double inverted U-type,which has certain reference significance for the development of subsequent environmental Kuznets curve.The analysis of the EKC curve of industrial water use in Ningxia reveals its formation reason and development trend,which is also of great significance for efficient and rational utilization of water resources in Ningxia and industrial watersaving in the future.
Water resources are the basic guarantee of economic development.In the utilization of water resources,industrial water use is more closely related to the economy,and they influence and feedback each other.To reveal their development relationship,the environmental Kuznets curve (EKC) is used for fitting prediction.In the past,researches on the environmental Kuznets curve only focused on the relationship between pollutants and the economy,and there was little pieces of research on water use.However,researches on the industrial water EKC just focus on the discussion of its shape and qualitative analysis and lack quantitative research.Given the shortcomings of the research,Ningxia is selected as the research area,which is deficient in water resources,and has problems such as unreasonable supply and demand structure of industrial water,imperfect management system,low reuse rate,and low utilization rate of unconventional water resources. The Kuznets curve of the industrial water environment is determined by adopting parameters and moving average regression fitting.The central and central Kuznets curve formation mechanism of the industrial water environment in Ningxia is analyzed quantitatively by the Logarithmic Mean Divisia Index (LMDI) to decompose the industrial water use effect into the water use efficiency effect,the industrial structure effect,and the economic scale effect.Finally,the grey prediction model is used to quantitatively predict the development of industrial water EKC in Ningxia in the future,and explore its possible evolution trend in the future. （1）The industrial water consumption in Ningxia increased continuously from 1980 to 1997,with an average annual growth rate of 57%.Water consumption continued to decrease from 1997 to 2004,with an average annual reduction rate of 3.9%.The fluctuation increased from the late period to 2013.It is found that the fitting result of the cubic model is more reasonable than that of a quadratic model,and the fitting degree is higher.From the moving average,it can also be seen that the curve presents a positive N-type.In conclusion,the Kuznets curve of the industrial water environment in Ningxia presents a positive Ntype in the interval from 1980 to 2013.（2）Using LMDI,the influencing factors of industrial water use in Ningxia were decomposed into water use efficiency effect,industrial structure effect,and economic scale effect.Among them,from the perspective of industry,each effect value of the heavy industry is greater than that of the light industry,indicating that heavy industry occupies the dominant position in Ningxia.From the perspective of effect,the effect of water use efficiency has a restraining effect on the increase of water consumption,the effect of economic scale has a promoting effect on the increase of water consumption,but the effect of industrial structure is different.When the sum of the three effects is negative,the water consumption will be saved.Otherwise,the water consumption will increase.It can be concluded that water consumption increased from 1990 to 1997 and from 2004 to 2007,but decreased from 1997 to 2004,showing N-type.Simultaneously,it is found that the change of industrial water consumption in Ningxia is in line with the policies and measures of industrial reform and opening up.（3）According to the prediction results of the grey model and relevant policy guidance,the logarithm of industrial water consumption in Ningxia has a decreasing trend,while the logarithm of per capita industrial GDP has an increasing trend.According to the two predictions,the EKC of industrial water consumption in Ningxia will develop downward in the future. From the above research,it is found that there is a certain relationship between social and economic development and industrial water use.It is reasonable to use the environmental Kuznets curve to fit.Together,it can be seen that the EKC shape of industrial water use is different,which needs to be discussed according to different regions.According to the reason analysis of EKC of industrial water use in Ningxia,the efficiency of industrial water use in Ningxia continues to be flat,so it should be kept continuing to improve the level of industrial water saving,enhance the technical strength,strengthen the ability of water resources monitoring,and promote the development of industrial structure in the direction of optimization and rationality,to further improve the effectiveness of watersaving.It is predicted that the EKC of industrial water use in Ningxia may appear M-type in the future,which indicates whether the curve has periodicity with the change of social economy,that is,double inverted U-type,which has certain reference significance for the development of subsequent environmental Kuznets curve.The analysis of the EKC curve of industrial water use in Ningxia reveals its formation reason and development trend,which is also of great significance for efficient and rational utilization of water resources in Ningxia and industrial watersaving in the future.
2021, 19(2):352-357.
Abstract:
Lingzhuangzi waterworks in water processing adopts drug concentration of water body method to monitor and to determine the reasonable dosage.The method first dosing and monitoring of drug concentrations,after initial dosage judging by experience,which wastes manpower and cannot guarantee the result accurately.The determined dosage must first clear streamflow,reservoir a submerged inlet for the nonstandard rectangle thinwall weir,therefore,unable to use the existing flow formula calculation flow of traffic.At the entrance of the weir,there are both free outflow and submerged outflow. To obtain a more accurate flow rate,the physical model test method was adopted,and the model with a geometric scale of 1∶5 was made according to the gravity similarity criterion for experimental research.The experiment is carried out to analyze the flow change process of the weir.The appropriate position of the weir before and after the weir at the inlet of the water plant reservoir is set up,and the corresponding physical model is made. The actual flow capacity of a rectangular thinwalled weir is reduced due to the influence of the weir plate groove.The empirical value of the flow coefficient was Cd1=0.056 9h/p+0.597,and the measured value was Cd2=0.828h/p+ 0.543 8,respectively.The free flow formula was calculated by Cd2without considering the influence of surface tension.Submerged discharge conditions can be used to scale according to different valve opening and close the valve opening as a group,the outlet valve opening corresponding to the actual engineering of the middle and lower reaches of reservoir level can be carried out on the downstream water level "sectional processing",namely the designated several water level range,as a set of each water level range,according to the flood discharge formula in the calculation,flow coefficient,different groups of corresponding parameters a and bvalues. Through the model test,the flow variation law of free flow and submerged flow of the weir in Lingzhuangzi waterworks are studied,the test results show that it is feasible to preliminarily calculate the overflow by the water level in front of the weir and behind the weir,and the calculation ideas of the flow are given respectively. Compared with the standard rectangular thinwalled weir,the weir plate groove of the water conservation weir in the waterworks reduces the free flow capacity,and the measured flow coefficient is Cd2=0.828 h/p+0.543 8.The free outflow can be calculated directly by formula using flow coefficient Cd2.When the outlet valve has a certain opening,the submerged water depth increases with the increase of the incoming flow;when the flow rate is constant,the submerged depth decreases with the increase of the opening of the outlet valve;and when the downstream valve opening is certain,the submergence coefficient Cf has a mathematical relationship with h/p,and the submergence coefficient Cf of several similar valve openings applies to the same value of a and b.Outlet valve opening corresponding to the actual engineering of the middle and lower reaches of reservoir level,according to different groups,the downstream water level giving to the flood discharge formula,refer to historical traffic data,the relationship between the primary parameter values constantly in the process of practical application to modify parameters,the accurate calculation formula can be obtained,and then the automatic control of dosage can be realized.
Lingzhuangzi waterworks in water processing adopts drug concentration of water body method to monitor and to determine the reasonable dosage.The method first dosing and monitoring of drug concentrations,after initial dosage judging by experience,which wastes manpower and cannot guarantee the result accurately.The determined dosage must first clear streamflow,reservoir a submerged inlet for the nonstandard rectangle thinwall weir,therefore,unable to use the existing flow formula calculation flow of traffic.At the entrance of the weir,there are both free outflow and submerged outflow. To obtain a more accurate flow rate,the physical model test method was adopted,and the model with a geometric scale of 1∶5 was made according to the gravity similarity criterion for experimental research.The experiment is carried out to analyze the flow change process of the weir.The appropriate position of the weir before and after the weir at the inlet of the water plant reservoir is set up,and the corresponding physical model is made. The actual flow capacity of a rectangular thinwalled weir is reduced due to the influence of the weir plate groove.The empirical value of the flow coefficient was Cd1=0.056 9h/p+0.597,and the measured value was Cd2=0.828h/p+ 0.543 8,respectively.The free flow formula was calculated by Cd2without considering the influence of surface tension.Submerged discharge conditions can be used to scale according to different valve opening and close the valve opening as a group,the outlet valve opening corresponding to the actual engineering of the middle and lower reaches of reservoir level can be carried out on the downstream water level "sectional processing",namely the designated several water level range,as a set of each water level range,according to the flood discharge formula in the calculation,flow coefficient,different groups of corresponding parameters a and bvalues. Through the model test,the flow variation law of free flow and submerged flow of the weir in Lingzhuangzi waterworks are studied,the test results show that it is feasible to preliminarily calculate the overflow by the water level in front of the weir and behind the weir,and the calculation ideas of the flow are given respectively. Compared with the standard rectangular thinwalled weir,the weir plate groove of the water conservation weir in the waterworks reduces the free flow capacity,and the measured flow coefficient is Cd2=0.828 h/p+0.543 8.The free outflow can be calculated directly by formula using flow coefficient Cd2.When the outlet valve has a certain opening,the submerged water depth increases with the increase of the incoming flow;when the flow rate is constant,the submerged depth decreases with the increase of the opening of the outlet valve;and when the downstream valve opening is certain,the submergence coefficient Cf has a mathematical relationship with h/p,and the submergence coefficient Cf of several similar valve openings applies to the same value of a and b.Outlet valve opening corresponding to the actual engineering of the middle and lower reaches of reservoir level,according to different groups,the downstream water level giving to the flood discharge formula,refer to historical traffic data,the relationship between the primary parameter values constantly in the process of practical application to modify parameters,the accurate calculation formula can be obtained,and then the automatic control of dosage can be realized.
2021, 19(2):358-364,377.
Abstract:
In the pressurized water supply project,the power failure accident will lead to the rapid decrease of the flow after the pump and the sudden change of the flow velocity in the pipeline,which will form the pumpstopping water hammer.Its specific characteristics are reflected in the significant decrease and increase of water pressure in the pipeline,which seriously endangers the safety of water supply projects.The water conveyance project with siphon breaking structure at the end of the pipeline is replacing the regulating valve in the conventional water conveyance project with siphon structure.When the pump is powered off,the siphon structure can quickly isolate the water flow between the pipeline and the downstream outlet pool,and suppress the water flow backward to the pipeline.Simultaneously,this structure can avoid large valveclosure water hammer,and the control of pipeline negative water hammer is mainly considered in water hammer protection. Based on the method of onedimensional characteristics,the mathematical models of vacuum breaking valve,air valve,and oneway surge tank were established and applied to the water conveyance project with siphon breaking structure at the end of the pipeline.Given the problem of water hammer protection in pipeline systems,three protection schemes were proposed:single vacuum breaking valve scheme,vacuum breaking valveair valve scheme and vacuum breaking valveoneway surge tank scheme.Combined with the control requirements of pipe pressure,when pumps are in power outage accident at dangerous conditions,three protection schemes were assessed in terms of the influence of the hydraulic transition process of pipeline systems. In the protection scheme of a single vacuum breaking valve,theoretically,the minimum pressure of the pipeline can reach -25 m,which is far lower than the water vaporization pressure of -10 m and may cause the water column bridging phenomenon,which seriously endangers the project safety.Under the combined protection scheme of vacuum breaking valveair valve,the minimum pressure of the pipeline is -994 m.Although the water vaporization pressure is not reached,it can not meet the requirements of minimum pressure control standard of -5 m under air valve protection.In the combined protection scheme of vacuum breaking valveoneway surge tank,the pressure at each point of the pipeline can meet the requirements of water hammer protection,which can effectively ensure project safety.In summary,the combined protection scheme of vacuum breaking valve and other water hammer protection measures can often achieve a better water hammer protection effect.For the water conveyance system with a large flow rate and gentle terrain,the protection method of a one-way surge tank by water supplement is better than that of an air valve by the gas supplement.Besides,when water hammer protection is carried out in the pipeline system with a large flow rate and fast flow rate,it is necessary to avoid gas being mixed into water pipelines. Given the water hammer protection problem in water conveyance project with siphon breaking structure at the end of the pipeline,the pipeline characteristics are analyzed,and different water hammer protection schemes are proposed.The protection schemes are analyzed and compared,and the following main conclusions are obtained: (1) The vacuum breaking valve has a good effect on the stable operation and water hammer protection of the siphon structure,but the water hammer protection of the whole pipeline system should be combined with other water hammer protection measures.(2) For the water conveyance project with a large flow rate,flat terrain and siphon breaking structure at the end of the pipeline,the water hammer protection measures combined with the air valve and vacuum breaking valve will cause a large amount of gas intake in the pipeline.After the valve is closed after the pump,a large number of water will impact the air valve,resulting in the acceleration of the exhaust speed of the air valve,making the gas column bridging pressure larger,and adversely affecting the positive and negative water hammer protection of the pipeline.(3) The water hammer protection measures combined with a one-way surge tank and vacuum breaking valve are adopted.The water and gas are separated by the siphon breaking structure through the way of water supplement by one-way surge tank and gas supplement by vacuum breaking valve,which prevents the mixing of gas in the pipeline water body,avoids the generation of gas column bridging phenomenon,and effectively ensures the safety of the pipeline.
In the pressurized water supply project,the power failure accident will lead to the rapid decrease of the flow after the pump and the sudden change of the flow velocity in the pipeline,which will form the pumpstopping water hammer.Its specific characteristics are reflected in the significant decrease and increase of water pressure in the pipeline,which seriously endangers the safety of water supply projects.The water conveyance project with siphon breaking structure at the end of the pipeline is replacing the regulating valve in the conventional water conveyance project with siphon structure.When the pump is powered off,the siphon structure can quickly isolate the water flow between the pipeline and the downstream outlet pool,and suppress the water flow backward to the pipeline.Simultaneously,this structure can avoid large valveclosure water hammer,and the control of pipeline negative water hammer is mainly considered in water hammer protection. Based on the method of onedimensional characteristics,the mathematical models of vacuum breaking valve,air valve,and oneway surge tank were established and applied to the water conveyance project with siphon breaking structure at the end of the pipeline.Given the problem of water hammer protection in pipeline systems,three protection schemes were proposed:single vacuum breaking valve scheme,vacuum breaking valveair valve scheme and vacuum breaking valveoneway surge tank scheme.Combined with the control requirements of pipe pressure,when pumps are in power outage accident at dangerous conditions,three protection schemes were assessed in terms of the influence of the hydraulic transition process of pipeline systems. In the protection scheme of a single vacuum breaking valve,theoretically,the minimum pressure of the pipeline can reach -25 m,which is far lower than the water vaporization pressure of -10 m and may cause the water column bridging phenomenon,which seriously endangers the project safety.Under the combined protection scheme of vacuum breaking valveair valve,the minimum pressure of the pipeline is -994 m.Although the water vaporization pressure is not reached,it can not meet the requirements of minimum pressure control standard of -5 m under air valve protection.In the combined protection scheme of vacuum breaking valveoneway surge tank,the pressure at each point of the pipeline can meet the requirements of water hammer protection,which can effectively ensure project safety.In summary,the combined protection scheme of vacuum breaking valve and other water hammer protection measures can often achieve a better water hammer protection effect.For the water conveyance system with a large flow rate and gentle terrain,the protection method of a one-way surge tank by water supplement is better than that of an air valve by the gas supplement.Besides,when water hammer protection is carried out in the pipeline system with a large flow rate and fast flow rate,it is necessary to avoid gas being mixed into water pipelines. Given the water hammer protection problem in water conveyance project with siphon breaking structure at the end of the pipeline,the pipeline characteristics are analyzed,and different water hammer protection schemes are proposed.The protection schemes are analyzed and compared,and the following main conclusions are obtained: (1) The vacuum breaking valve has a good effect on the stable operation and water hammer protection of the siphon structure,but the water hammer protection of the whole pipeline system should be combined with other water hammer protection measures.(2) For the water conveyance project with a large flow rate,flat terrain and siphon breaking structure at the end of the pipeline,the water hammer protection measures combined with the air valve and vacuum breaking valve will cause a large amount of gas intake in the pipeline.After the valve is closed after the pump,a large number of water will impact the air valve,resulting in the acceleration of the exhaust speed of the air valve,making the gas column bridging pressure larger,and adversely affecting the positive and negative water hammer protection of the pipeline.(3) The water hammer protection measures combined with a one-way surge tank and vacuum breaking valve are adopted.The water and gas are separated by the siphon breaking structure through the way of water supplement by one-way surge tank and gas supplement by vacuum breaking valve,which prevents the mixing of gas in the pipeline water body,avoids the generation of gas column bridging phenomenon,and effectively ensures the safety of the pipeline.
2021, 19(2):365-377.
Abstract:
The Middle Route of South-to-North Water Transfer Project is a great longdistance water transfer project that solves the problem of the uneven spatial distribution of water resources in China.It crosses three climatic zones.The ice conditions are complex and changeable in the winter.If the operation method is inappropriate,it is easy to cause ice damage,which may even block the main channel and cause water supply interruption.Ice clogging is the main ice damage in the Middle Route of SouthtoNorth Water Transfers Project during transferring water in the winter.The occurrence and development of ice clogging are related to hydraulic,thermal,and frozen factors.Therefore,the control of influencing factors to ice clogging,such as water depth and flow velocity,is vital to reduce the occurrence probability of ice clogging disaster and guarantee the water supply security for the project transferring water in the winter. The channel between Fenzhuang River Regulator and Nanjuma River Regulator was taken as a case study,since it has a greater risk of ice damage in the Middle Route of South-to-North Water Transfers Project.Firstly,based on the theories of hydrodynamics,thermodynamics,and ice hydraulics,a loosely coupled thermodynamic-hydraulic-ice mechanics ice evolution numerical model is established.The model is calibrated and verified with the observational data of the winter ice thickness from 2010 to 2011 and the measured water level and water temperature data in the winter of from 2014 to 2019.Secondly,the forming conditions and influencing factors of ice clogging were comprehensively considered,and different combinations of water depth,flow velocity,and temperature were setup according to the actual operation of the canal after the formal operation and historical temperature changes and ice conditions changes.Thirdly,based on the above research,the changes in ice conditions were quantitatively analyzed under different combination of scenarios,and ice clogging were found out under different water depths,flow rates,and water temperature changes.The indexes of flow velocity control and air temperature early warning were determined,and a scheduling strategy was proposed to ensure the safety of water transfer in the study canal in the winter.Finally,the combined scenarios of water depth,flow velocity,and temperature that were most likely to occur in ice clogging were used to verify the scheduling strategy. The results show that:the ice evolution numerical model meets the accuracy requirements for the simulation results of the ice condition related factors such as water level,water temperature,and ice cover thickness in the study canal,and can more accurately reflect the ice condition changes in the study canal in the winter and can be used in analyzing and researching on the characteristics of ice clogging changes and scheduling strategy in the winter.The ice clogging shows different variation characteristics under different hydraulic and thermal conditions.For example:when the water depth is less than 4.0 m,the high flow rate is prone to ice clogging and the thickness of ice clogging is small;when the water depth is equal or greater than 4.0 m,the low flow rate is prone to ice clogging and the thickness of ice clogging is large;when the negative accumulated temperature is equal or less than -150 ℃,the risk probability of ice clogging is high.The velocity control index and air temperature early warning index of water transfer in the winter is determined,and based on this,the scheduling strategy to ensure the safety of water supply in the winter of the Middle Route of South-to-North Water Transfer Project is put forward,which is normal water transfer when the negative accumulated temperature is greater than -150 ℃,the flow rate is maintained at 0.2 m/s when the negative accumulated temperature is less than -150 ℃ and the water depth is less than 4.0 m,and the flow rate is maintained at 0.6 m/s when the negative accumulated temperature is less than -150 ℃ and the water depth is equal and greater than 4.0 m;after the implementation of the winter scheduling strategy,the risk probability of ice clogging in the combination scenario most likely to occur decreased from 4.054% and 2.225% to 0.001%,respectively,which significantly reduced the probability of ice clogging and effectively guaranteed the water supply security in the ice period. Based on the construction of the ice evolution numerical model,the different combined working conditions are set up,the influence of hydraulic and thermal factors on ice condition changes are quantitatively analyzed,and a set of scheduling strategies that can significantly reduce the risk of ice jams are farmulated.The results provide certain references for the actual dispatch of the Middle Route of South-to-North Water Transfer Project in the winter,which is of great significance for ensuring the water supply security in the winter.
The Middle Route of South-to-North Water Transfer Project is a great longdistance water transfer project that solves the problem of the uneven spatial distribution of water resources in China.It crosses three climatic zones.The ice conditions are complex and changeable in the winter.If the operation method is inappropriate,it is easy to cause ice damage,which may even block the main channel and cause water supply interruption.Ice clogging is the main ice damage in the Middle Route of SouthtoNorth Water Transfers Project during transferring water in the winter.The occurrence and development of ice clogging are related to hydraulic,thermal,and frozen factors.Therefore,the control of influencing factors to ice clogging,such as water depth and flow velocity,is vital to reduce the occurrence probability of ice clogging disaster and guarantee the water supply security for the project transferring water in the winter. The channel between Fenzhuang River Regulator and Nanjuma River Regulator was taken as a case study,since it has a greater risk of ice damage in the Middle Route of South-to-North Water Transfers Project.Firstly,based on the theories of hydrodynamics,thermodynamics,and ice hydraulics,a loosely coupled thermodynamic-hydraulic-ice mechanics ice evolution numerical model is established.The model is calibrated and verified with the observational data of the winter ice thickness from 2010 to 2011 and the measured water level and water temperature data in the winter of from 2014 to 2019.Secondly,the forming conditions and influencing factors of ice clogging were comprehensively considered,and different combinations of water depth,flow velocity,and temperature were setup according to the actual operation of the canal after the formal operation and historical temperature changes and ice conditions changes.Thirdly,based on the above research,the changes in ice conditions were quantitatively analyzed under different combination of scenarios,and ice clogging were found out under different water depths,flow rates,and water temperature changes.The indexes of flow velocity control and air temperature early warning were determined,and a scheduling strategy was proposed to ensure the safety of water transfer in the study canal in the winter.Finally,the combined scenarios of water depth,flow velocity,and temperature that were most likely to occur in ice clogging were used to verify the scheduling strategy. The results show that:the ice evolution numerical model meets the accuracy requirements for the simulation results of the ice condition related factors such as water level,water temperature,and ice cover thickness in the study canal,and can more accurately reflect the ice condition changes in the study canal in the winter and can be used in analyzing and researching on the characteristics of ice clogging changes and scheduling strategy in the winter.The ice clogging shows different variation characteristics under different hydraulic and thermal conditions.For example:when the water depth is less than 4.0 m,the high flow rate is prone to ice clogging and the thickness of ice clogging is small;when the water depth is equal or greater than 4.0 m,the low flow rate is prone to ice clogging and the thickness of ice clogging is large;when the negative accumulated temperature is equal or less than -150 ℃,the risk probability of ice clogging is high.The velocity control index and air temperature early warning index of water transfer in the winter is determined,and based on this,the scheduling strategy to ensure the safety of water supply in the winter of the Middle Route of South-to-North Water Transfer Project is put forward,which is normal water transfer when the negative accumulated temperature is greater than -150 ℃,the flow rate is maintained at 0.2 m/s when the negative accumulated temperature is less than -150 ℃ and the water depth is less than 4.0 m,and the flow rate is maintained at 0.6 m/s when the negative accumulated temperature is less than -150 ℃ and the water depth is equal and greater than 4.0 m;after the implementation of the winter scheduling strategy,the risk probability of ice clogging in the combination scenario most likely to occur decreased from 4.054% and 2.225% to 0.001%,respectively,which significantly reduced the probability of ice clogging and effectively guaranteed the water supply security in the ice period. Based on the construction of the ice evolution numerical model,the different combined working conditions are set up,the influence of hydraulic and thermal factors on ice condition changes are quantitatively analyzed,and a set of scheduling strategies that can significantly reduce the risk of ice jams are farmulated.The results provide certain references for the actual dispatch of the Middle Route of South-to-North Water Transfer Project in the winter,which is of great significance for ensuring the water supply security in the winter.
2021, 19(2):378-384.
Abstract:
Hydraulic jump is a hydraulic phenomenon in open channel flow.In hydraulic conservancy projects,the severe scouring and erosion of the downstream riverbed are primarily induced by the violent turbulence of the downstream flow,thus establishing a corrugated bed in the stilling basin to develop hydraulic jump can improve the energy dissipation effect and reduce the damage to the buildings.At present,the research on the corrugated bed is mainly based on the experimental results and grid method of triangular corrugated bed.However,there are few systematic studies on the hydraulic jump characteristics of the triangular corrugated bed using WCSPH(Weakly Compressible Smoothed Particle Hydrodynamics) method.Exploring the hydraulic jump characteristics of the triangular corrugated bed has certain significance for the construction of the stilling basin. The open source code SPHYSICS_2D is used to perform numerical calculations.A push plate is used to provide stable flow and the upstream water depth is used to control the flow.Numerical simulations (the particle distance dx=0.005 m) were carried out on 20 groups cases with the ratio of wavelength to wave height (S/t) of 1,2,3,4,and 5 and Fr of 1.68,2.47,4.45,and 6.08,then the hydraulic jump characteristics,such as flow pattern,velocity distribution,conjugate depth and energy dissipation rate on the triangular corrugated bed,are analyzed in details. The comparison between the simulation and experimental results shows that the numerical simulation results is in accordance with the experimental results.A downstream flow is developed at the gate and the surface of the water flow,a part of the flow back is formed at the bottom of the triangular corrugated bed due to the obstruction of the main flow area.The flow makes a violent whirl motion on the surface rolling zone and the triangular corrugated bed increases the boundary layer and roughness contributing to the formation of a vortex.Compared with the experimental results,the errors of the simulated and experimental values of the conjugate depth of the five waveforms are 1.50%,1.96%,2.68%,067% and 0.08%,respectively.Compared with the smooth bed,the energy dissipation rates of the five waveforms are increased by 47.53%,44.33%,48.52%,41.18% and 37.41%,respectively.Among them,the energy dissipation effect of the waveform S/t=3 is better than that of other corrugated bed,and the energy dissipation rate is the largest with the same Fr,that is,the energy dissipation effect is the best.On the best triangular corrugated bed (S/t=3) with Fr=1.68,2.47,4.45,6.08,the conjugate depth is reduced by 10.55%,14.12%,15.81% and 16.09%,respectively,while the energy dissipation rate is increased by 84.91%,48.58%,35.42% and 32.20%,respectively,compared with the one on the smoothed bed. The WCSPH method can better simulate the hydraulic jump characteristics of the triangular corrugated bed.Compared with the smooth bed,the hydraulic jump length and conjugate depth of the triangular corrugated bed have been reduced,and the energy dissipation effect is better than that of the smooth bed.The surface on the triangular corrugated bed will exhibit a clockwise vortex,and the size of the vortex will gradually decrease with the direction of the water flow.In the hydraulic jump section,the middle velocity is higher and the surface velocity is smaller;in the open channel section,the bottom velocity is smaller and the surface velocity is larger.Therefore,the triangular corrugated bed can increase energy dissipation and improve energy dissipation rate.Meanwhile,with an analysis of the hydraulic jump characteristics of different cases indicates that the best triangular corrugated bed is S/t=3,and its conjugate depth is 14.15% less than the average of the smooth bed,and increases with the increase of Fr;the energy rate is 48.52% higher than that of the smooth bed,and decreases with the increase of Fr.
Hydraulic jump is a hydraulic phenomenon in open channel flow.In hydraulic conservancy projects,the severe scouring and erosion of the downstream riverbed are primarily induced by the violent turbulence of the downstream flow,thus establishing a corrugated bed in the stilling basin to develop hydraulic jump can improve the energy dissipation effect and reduce the damage to the buildings.At present,the research on the corrugated bed is mainly based on the experimental results and grid method of triangular corrugated bed.However,there are few systematic studies on the hydraulic jump characteristics of the triangular corrugated bed using WCSPH(Weakly Compressible Smoothed Particle Hydrodynamics) method.Exploring the hydraulic jump characteristics of the triangular corrugated bed has certain significance for the construction of the stilling basin. The open source code SPHYSICS_2D is used to perform numerical calculations.A push plate is used to provide stable flow and the upstream water depth is used to control the flow.Numerical simulations (the particle distance dx=0.005 m) were carried out on 20 groups cases with the ratio of wavelength to wave height (S/t) of 1,2,3,4,and 5 and Fr of 1.68,2.47,4.45,and 6.08,then the hydraulic jump characteristics,such as flow pattern,velocity distribution,conjugate depth and energy dissipation rate on the triangular corrugated bed,are analyzed in details. The comparison between the simulation and experimental results shows that the numerical simulation results is in accordance with the experimental results.A downstream flow is developed at the gate and the surface of the water flow,a part of the flow back is formed at the bottom of the triangular corrugated bed due to the obstruction of the main flow area.The flow makes a violent whirl motion on the surface rolling zone and the triangular corrugated bed increases the boundary layer and roughness contributing to the formation of a vortex.Compared with the experimental results,the errors of the simulated and experimental values of the conjugate depth of the five waveforms are 1.50%,1.96%,2.68%,067% and 0.08%,respectively.Compared with the smooth bed,the energy dissipation rates of the five waveforms are increased by 47.53%,44.33%,48.52%,41.18% and 37.41%,respectively.Among them,the energy dissipation effect of the waveform S/t=3 is better than that of other corrugated bed,and the energy dissipation rate is the largest with the same Fr,that is,the energy dissipation effect is the best.On the best triangular corrugated bed (S/t=3) with Fr=1.68,2.47,4.45,6.08,the conjugate depth is reduced by 10.55%,14.12%,15.81% and 16.09%,respectively,while the energy dissipation rate is increased by 84.91%,48.58%,35.42% and 32.20%,respectively,compared with the one on the smoothed bed. The WCSPH method can better simulate the hydraulic jump characteristics of the triangular corrugated bed.Compared with the smooth bed,the hydraulic jump length and conjugate depth of the triangular corrugated bed have been reduced,and the energy dissipation effect is better than that of the smooth bed.The surface on the triangular corrugated bed will exhibit a clockwise vortex,and the size of the vortex will gradually decrease with the direction of the water flow.In the hydraulic jump section,the middle velocity is higher and the surface velocity is smaller;in the open channel section,the bottom velocity is smaller and the surface velocity is larger.Therefore,the triangular corrugated bed can increase energy dissipation and improve energy dissipation rate.Meanwhile,with an analysis of the hydraulic jump characteristics of different cases indicates that the best triangular corrugated bed is S/t=3,and its conjugate depth is 14.15% less than the average of the smooth bed,and increases with the increase of Fr;the energy rate is 48.52% higher than that of the smooth bed,and decreases with the increase of Fr.
2021, 19(2):385-392.
Abstract:
Southwest drainage tunnel of Hangzhou City is a comprehensive water conservancy project to solve the problem of flood control and drainage in west Hangzhou.The exit of the project is to be located near the Yanshanhe sluice in Jiuxi section of Qiantang River.The Jiuxi section is located at the end of the estuary of the Qiantang River .Due to interaction of runoff and tide,the riverbed erosion and deposition of the section are relatively complex.However,after long-term regulation,the width of the narrowest section of the section has been stabilized at about 1 km.This section of the river is relatively open,the north side of the flood embankment line can be appropriately optimized,combined with the implemented Hangzhou southwest drainage channel project,outlet drainage pumping station can get a comprehensive benefit. The two dimensional mathematical model of tidal current and sediment is used to calculate the influence of density pressure caused by sediment concentration on the flow movement.The flow control equations include the continuity equation and the momentum equation.Only suspended sediment is considered in the sediment field,and the governing equation is the convection-diffusion equation.The flow control equations are solved by the finite volume-KFVS scheme,and the sediment transport equations are solved by the finite volumeaccurate Riemann method.In addition to the requirements of fast convergence,good stability,and high accuracy of the discrete scheme,the establishment of the mathematical model mainly involves the rational determination of some important parameters,which can meet the verification requirements of the measured data under the conditions of large and small tides,flood and dry discharge and so on.To fully reflect the dynamic characteristics of the combined action of tidal flow and runoff in the engineering reach,the upper boundary of the numerical simulation study area is arranged at the Fuchunjiang power station,the lower boundary is arranged at the Ganpu section,and the grid of the Jiuxi reach is partially densified,the minimum grid size is about 2 m,and the tributaries are considered by side inflow.The tidal level of the model is verified by the Hydrologic Survey data in the engineering reach during the spring tide period in June 2018,and the flood level is verified by the flood data in June 2011.After verification,the model simulates the two schemes of the levee moving out and compares the backwater height and velocity variation of the levee in Qiantang River before and after the implementation of the project. The model results show that the backwater height in front of the levee is more obvious when the levee meets the high tide in Qiantang River once in a century,the maximum is 0.05 m,but the backwater height on the opposite bank is less than 0.01 m,the velocity of the opposite bank increases about 2%,but the velocity of the water in front of the bank does not change much.When encountering Qiantang River′s flood,the local water level of the project reach rises by 0.01 m,the velocity of flow in front of the embankment increases by 1% to 2%,and the velocity of flow along the bank of the irrigation and drainage station increases by 2% to 3%,the influence of flow velocity in front of the embankment of Shanhusha Reservoir is small. The moving of the levee line is not only beneficial to the layout of the pump and sluice project,but also to the release of a large enough water area for pressure regulation before the pump,a partially narrowed trumpetshaped body of water was reconstructed to reproduce the tidal bore.On the whole,the optimization of the embankment of Jiuxi Bank has little influence on flood control and tide resistance of Qiantang River and does not influence the water-related projects such as metro line 6,Qiantang River Bridge in the region.
Southwest drainage tunnel of Hangzhou City is a comprehensive water conservancy project to solve the problem of flood control and drainage in west Hangzhou.The exit of the project is to be located near the Yanshanhe sluice in Jiuxi section of Qiantang River.The Jiuxi section is located at the end of the estuary of the Qiantang River .Due to interaction of runoff and tide,the riverbed erosion and deposition of the section are relatively complex.However,after long-term regulation,the width of the narrowest section of the section has been stabilized at about 1 km.This section of the river is relatively open,the north side of the flood embankment line can be appropriately optimized,combined with the implemented Hangzhou southwest drainage channel project,outlet drainage pumping station can get a comprehensive benefit. The two dimensional mathematical model of tidal current and sediment is used to calculate the influence of density pressure caused by sediment concentration on the flow movement.The flow control equations include the continuity equation and the momentum equation.Only suspended sediment is considered in the sediment field,and the governing equation is the convection-diffusion equation.The flow control equations are solved by the finite volume-KFVS scheme,and the sediment transport equations are solved by the finite volumeaccurate Riemann method.In addition to the requirements of fast convergence,good stability,and high accuracy of the discrete scheme,the establishment of the mathematical model mainly involves the rational determination of some important parameters,which can meet the verification requirements of the measured data under the conditions of large and small tides,flood and dry discharge and so on.To fully reflect the dynamic characteristics of the combined action of tidal flow and runoff in the engineering reach,the upper boundary of the numerical simulation study area is arranged at the Fuchunjiang power station,the lower boundary is arranged at the Ganpu section,and the grid of the Jiuxi reach is partially densified,the minimum grid size is about 2 m,and the tributaries are considered by side inflow.The tidal level of the model is verified by the Hydrologic Survey data in the engineering reach during the spring tide period in June 2018,and the flood level is verified by the flood data in June 2011.After verification,the model simulates the two schemes of the levee moving out and compares the backwater height and velocity variation of the levee in Qiantang River before and after the implementation of the project. The model results show that the backwater height in front of the levee is more obvious when the levee meets the high tide in Qiantang River once in a century,the maximum is 0.05 m,but the backwater height on the opposite bank is less than 0.01 m,the velocity of the opposite bank increases about 2%,but the velocity of the water in front of the bank does not change much.When encountering Qiantang River′s flood,the local water level of the project reach rises by 0.01 m,the velocity of flow in front of the embankment increases by 1% to 2%,and the velocity of flow along the bank of the irrigation and drainage station increases by 2% to 3%,the influence of flow velocity in front of the embankment of Shanhusha Reservoir is small. The moving of the levee line is not only beneficial to the layout of the pump and sluice project,but also to the release of a large enough water area for pressure regulation before the pump,a partially narrowed trumpetshaped body of water was reconstructed to reproduce the tidal bore.On the whole,the optimization of the embankment of Jiuxi Bank has little influence on flood control and tide resistance of Qiantang River and does not influence the water-related projects such as metro line 6,Qiantang River Bridge in the region.
2021, 19(2):393-399.
Abstract:
The cemented sand-gravel dam is a new type of dam between the granular dam and the rigid dam.The two main aspects of controlling the quality of the cemented sand-gravel are compressive strength and density.In terms of strength,the maximum particle size of the cemented sand gravel material aggregate is 150 mm.According to the existing concrete test regulations,the full-graded test piece of this material should be a cube with a side length of 450 mm,but the production of the test piece is laborious and time-consuming,the cost is high;in terms of density control,the traditional irrigation method test takes a long time and affects the progress of the project,so it is necessary to find a simpler alternative method to simplify the test and reduce various cost inputs. Strength:150 mm cube specimens with a side length of 150 mm (eliminate particles above 40 mm) and 450 mm cube specimens with a side length of 450 mm (fullgraded test specimens) were prepared.The 150 mm cube specimens were cured for 14 days and 28 days,with a side length of 450 mm.The compressive strength test was carried out after reaching the corresponding prescribed age of cured cubes for 180 days.For the obtained compressive strength test data,linear fitting was performed by the least square method,and the linear relationship between the 14-day age of the 150 mm cube specimen and the 180day age of the 450 mm cube specimen was obtained.In terms of density,the rolling test site for the density test is arranged on the left bank platform between the upstream of the dam and the downstream of the cofferdam,with an area of 2,400 m2 (40 m×60 m).Twenty-eight measuring points were evenly distributed in the test site.First,the density was checked by a nuclear densitometer,and then a pit was dug at the same location for density parallel inspection by irrigation method.The diameter of the test pit was 450 mm and the depth was 450 mm.Similarly,the least square method is used to linearly fit the measured data,and the linear relationship fitting formula of the density result is obtained.To further verify the effectiveness of the nuclear densitometer test method,a verification analysis was performed at the initial stage of the dam filling in 2015,and the number of samples was increased to 30,and the linear formula fitted by the two methods was also obtained. The fitting result of the 14-day small specimens and the 180-day large specimen shows that the fitting curve is R180=1.542 7R14-4.951 93,and the correlation coefficient r=0.97.The fitting result of the 28 day small specimens and the 180 day large specimen shows that the fitting curve is R180=1.607 8R28-8.758 7,and the correlation coefficient r=0.95.The fitting curve of the density measured by the nuclear density meter and the density data measured by the irrigation method is γi=0.822 6γn+427.046 27,and the correlation coefficient r=0.90;the fitting curve obtained from the initial verification test of dam filling is γi=0.829 68γn+417.720 57,the correlation coefficient r=0.90. The fitting correlation coefficients obtained by the two test methods are both greater than 0.80,which meets the requirements of the project.The above test methods used have been verified and applied during the construction of the project,and also have been tested in parallel.It shows that the testing methods for the compressive strength and density of cemented sand and gravel described are effective and feasible,which may solve many existing problems in conventional testing methods,and may also provide a good reference for similar projects in the future.
The cemented sand-gravel dam is a new type of dam between the granular dam and the rigid dam.The two main aspects of controlling the quality of the cemented sand-gravel are compressive strength and density.In terms of strength,the maximum particle size of the cemented sand gravel material aggregate is 150 mm.According to the existing concrete test regulations,the full-graded test piece of this material should be a cube with a side length of 450 mm,but the production of the test piece is laborious and time-consuming,the cost is high;in terms of density control,the traditional irrigation method test takes a long time and affects the progress of the project,so it is necessary to find a simpler alternative method to simplify the test and reduce various cost inputs. Strength:150 mm cube specimens with a side length of 150 mm (eliminate particles above 40 mm) and 450 mm cube specimens with a side length of 450 mm (fullgraded test specimens) were prepared.The 150 mm cube specimens were cured for 14 days and 28 days,with a side length of 450 mm.The compressive strength test was carried out after reaching the corresponding prescribed age of cured cubes for 180 days.For the obtained compressive strength test data,linear fitting was performed by the least square method,and the linear relationship between the 14-day age of the 150 mm cube specimen and the 180day age of the 450 mm cube specimen was obtained.In terms of density,the rolling test site for the density test is arranged on the left bank platform between the upstream of the dam and the downstream of the cofferdam,with an area of 2,400 m2 (40 m×60 m).Twenty-eight measuring points were evenly distributed in the test site.First,the density was checked by a nuclear densitometer,and then a pit was dug at the same location for density parallel inspection by irrigation method.The diameter of the test pit was 450 mm and the depth was 450 mm.Similarly,the least square method is used to linearly fit the measured data,and the linear relationship fitting formula of the density result is obtained.To further verify the effectiveness of the nuclear densitometer test method,a verification analysis was performed at the initial stage of the dam filling in 2015,and the number of samples was increased to 30,and the linear formula fitted by the two methods was also obtained. The fitting result of the 14-day small specimens and the 180-day large specimen shows that the fitting curve is R180=1.542 7R14-4.951 93,and the correlation coefficient r=0.97.The fitting result of the 28 day small specimens and the 180 day large specimen shows that the fitting curve is R180=1.607 8R28-8.758 7,and the correlation coefficient r=0.95.The fitting curve of the density measured by the nuclear density meter and the density data measured by the irrigation method is γi=0.822 6γn+427.046 27,and the correlation coefficient r=0.90;the fitting curve obtained from the initial verification test of dam filling is γi=0.829 68γn+417.720 57,the correlation coefficient r=0.90. The fitting correlation coefficients obtained by the two test methods are both greater than 0.80,which meets the requirements of the project.The above test methods used have been verified and applied during the construction of the project,and also have been tested in parallel.It shows that the testing methods for the compressive strength and density of cemented sand and gravel described are effective and feasible,which may solve many existing problems in conventional testing methods,and may also provide a good reference for similar projects in the future.
2021, 19(2):400-408.
Abstract:
The curtain anti-seepage structure requires both good anti-seepage performance,as well as anti-shear and hydraulic splitting resistance under high osmotic pressure,which prevents the risk of hydraulic fracturing damage inside the anti-seepage layer.In the construction of traditional cementsoil mixing piles,the fibers are directly mixed with cement slurry.The fibers generally agglomerate and float on the surface of the slurry or settle down,so it is difficult to achieve uniform dispersion.Simultaneously,the biaxial or triaxial cementsoil mixing pile is mainly mixed horizontally inside a single soil layer,and the fibers will be concentrated in the local depth of the cementsoil cutoff wall,which makes it difficult to guarantee the overall quality of the cutoff wall.In the construction site,the direct mixing method to mix basalt fiber and cemen-soil can not meet the uniformity requirements.Basalt fiber concentration will occur at the bottom or part of the wall,which can easily block the slurry outlet of the TRD host. The basalt fiber was selected as a reinforcing material to improve the tensile strength of cement-soil,and the measurement was conducted on splitting and tensile properties of basalt fiber reinforced cutoff wall by TRD.Selection of an external admixture to make the fiber bundles became monofilaments and disperse in the cement slurry.Through the mixing dispersion test,the mixing effects of yellow sand,gypsum powder,plain fill,and sodium bentonite as dispersing mixing materials were studied respectively,and the results were obtained.The basalt fiber reinforced TRD antiseepage wall construction mixing dispersion material was based on the composition of mass parts,so the on-site mixing process was systematically studied to achieve uniform dispersion of basalt fiber in cement soil during TRD construction and proposes basalt fiber addition construction method of reinforced TRD cut-off wall.The basalt fiber reinforced TRD cut-off wall was drilled and sampled by the open thin-wall soil extractor,and the core sample preparation was carried out by the thin-walled bulldozing and ring knife sample method.The size of the prepared sample was 50 mm×100 mm.The split tensile strength test was carried out on the cored sample,and the obtained tensile strength was converted by applying the linear elastic theory.Then,the influence of cement and basalt fiber content,basalt fiber length,curing age,and other factors on the hydraulic fracturing characteristics of basalt fiber reinforced TRD cut-off wall were also discussed. The experimental results indicated that the composition of the construction mixing dispersion material in parts by mass was:P.O 42.5 grade ordinary Portland cement,with the mixing amount wass 25% and watercement-ratio of 1.3.The sodiumbased bentonite,with a mixing amount of 100 kg/m3 and watercement-ratio of 18.6,and basalt fiber,which mixing amount was 0.4%,respectively.When curing for 28 d,0.4% of basalt fiber added to the cement-soil sample can obtain a tensile strength growth rate of 50.0%.The tensile strength of reinforced cement-soil increased first and then decreased due to the increased basalt fiber content and length.The optimal basalt fiber was 12 mm long with the content of 0.4%. The proposed basalt fiber reinforcement technology can make the basalt fiber monofilament evenly distributed in the cement soil,and the final dispersion has a moderate consistency to facilitate mechanical mixing with the soil.Adding basalt fiber to cement-soil can effectively increase the tensile strength within a certain range,and can effectively improve the hydraulic splitting resistance of the cement-soil impervious wall.As the curing age increases,the tensile strength of the sample also increases.
The curtain anti-seepage structure requires both good anti-seepage performance,as well as anti-shear and hydraulic splitting resistance under high osmotic pressure,which prevents the risk of hydraulic fracturing damage inside the anti-seepage layer.In the construction of traditional cementsoil mixing piles,the fibers are directly mixed with cement slurry.The fibers generally agglomerate and float on the surface of the slurry or settle down,so it is difficult to achieve uniform dispersion.Simultaneously,the biaxial or triaxial cementsoil mixing pile is mainly mixed horizontally inside a single soil layer,and the fibers will be concentrated in the local depth of the cementsoil cutoff wall,which makes it difficult to guarantee the overall quality of the cutoff wall.In the construction site,the direct mixing method to mix basalt fiber and cemen-soil can not meet the uniformity requirements.Basalt fiber concentration will occur at the bottom or part of the wall,which can easily block the slurry outlet of the TRD host. The basalt fiber was selected as a reinforcing material to improve the tensile strength of cement-soil,and the measurement was conducted on splitting and tensile properties of basalt fiber reinforced cutoff wall by TRD.Selection of an external admixture to make the fiber bundles became monofilaments and disperse in the cement slurry.Through the mixing dispersion test,the mixing effects of yellow sand,gypsum powder,plain fill,and sodium bentonite as dispersing mixing materials were studied respectively,and the results were obtained.The basalt fiber reinforced TRD antiseepage wall construction mixing dispersion material was based on the composition of mass parts,so the on-site mixing process was systematically studied to achieve uniform dispersion of basalt fiber in cement soil during TRD construction and proposes basalt fiber addition construction method of reinforced TRD cut-off wall.The basalt fiber reinforced TRD cut-off wall was drilled and sampled by the open thin-wall soil extractor,and the core sample preparation was carried out by the thin-walled bulldozing and ring knife sample method.The size of the prepared sample was 50 mm×100 mm.The split tensile strength test was carried out on the cored sample,and the obtained tensile strength was converted by applying the linear elastic theory.Then,the influence of cement and basalt fiber content,basalt fiber length,curing age,and other factors on the hydraulic fracturing characteristics of basalt fiber reinforced TRD cut-off wall were also discussed. The experimental results indicated that the composition of the construction mixing dispersion material in parts by mass was:P.O 42.5 grade ordinary Portland cement,with the mixing amount wass 25% and watercement-ratio of 1.3.The sodiumbased bentonite,with a mixing amount of 100 kg/m3 and watercement-ratio of 18.6,and basalt fiber,which mixing amount was 0.4%,respectively.When curing for 28 d,0.4% of basalt fiber added to the cement-soil sample can obtain a tensile strength growth rate of 50.0%.The tensile strength of reinforced cement-soil increased first and then decreased due to the increased basalt fiber content and length.The optimal basalt fiber was 12 mm long with the content of 0.4%. The proposed basalt fiber reinforcement technology can make the basalt fiber monofilament evenly distributed in the cement soil,and the final dispersion has a moderate consistency to facilitate mechanical mixing with the soil.Adding basalt fiber to cement-soil can effectively increase the tensile strength within a certain range,and can effectively improve the hydraulic splitting resistance of the cement-soil impervious wall.As the curing age increases,the tensile strength of the sample also increases.
2021, 19(2):409-416.
Abstract:
To prevent accidents caused by the hidden danger of hydraulic steel gates and to avoid the waste of manpower and material resources in overhaul and maintenance process,it is necessary to evaluate the safety grade of the hydraulic steel gate.At present,there are many models for the safety grade evaluation of hydraulic steel gates at home and abroad,but most of them are only applicable to the traditional periodic inspection,while few models for online safety grade evaluation system .The hydraulic steel gate safety ratings can be abstracted as a pattern recognition problem,and the BP neural network is widely used in various fields of pattern recognition because of the strong learning ability,ability to adapt,and fault tolerance.Thus BP neural network can be constructed for the security level of hydraulic steel gate recognition model.Therefore,exploring the neural network for the safety of hydraulic steel gate online evaluation system is feasible.There are too many evaluation indexes of the traditional hydraulic steel gate safety grade,which leads to the redundancy of the input feature vector dimension.Moreover,if the initial value of the BP neural network is not good,it is easy to cause the training result to fall into the local optimal.So,the accuracy of BP neural network for the identification of the safety grade of hydraulic steel gates is not ideal. Since the information gain (IG) can achieve the quantification of the safety level of hydraulic steel gate and the correlation between each feature.The self-adaptive flower pollination algorithm (SFPA) has a strong global search ability and a local search ability and can realize the optimization of the initial value of BP neural network.Given this,an IG-SPAF-BP neural network model is proposed.According to the change of entropy,the information gain of each hydraulic steel gate safety grade feature is calculated,and the features carrying more information are selected as the input features of the neural network to reduce the training time of the neural network and improve the generalization ability of the neural network.By using the global and local pollination of the SFPA algorithm,the initial weight and initial threshold of the BP neural network are optimized to further improve the convergence speed of the BP neural network and the identification accuracy of the safety grade of the hydraulic steel gate. The repeated operation results of the IG-SFPA-BP network model,the standard BP network model,the IGBP network model,the IG-FPA-BP network model,the IG-GA-BP network model,and the IG-PSO-BP network model on the hydraulic steel gate sample set were compared.The experimental results show that in the above five kinds of models,the average recognition accuracy of the IG-SFPA-BP network model is the highest.However,the average running time of the IG-SFPA-BP network model is longer than that of the standard BP network model,IGBP network model,and IG-GA-BP network model,and compared with IG-GA-BP network model and IG-PSO-BP network running time is shorter.Besides,the mean square error of the IG-SFPA-BP network model is the smallest and the error curve is the most stable. The information gain theory reduces the dimension of the feature vector for the identification of the safety grade of hydraulic steel gate,shortening the running time of BP network and improving the classification ability of the network to a certain extent.SPFA algorithm can significantly improve the accuracy of the BP neural network in identifying the safety level of the hydraulic steel gate.IG-SFPA-BP model has good applicability for the identification of the safety grade of the hydraulic steel gate.According to the comparative test,its learning ability,generalization ability,and stability are better than those of standard BP,IG-BP,IG-FPA-BP,IG-GA-BP,and IG-PSO-BP network models.It can provide algorithm support for an online evaluation system of safety grade of hydraulic steel gate,and provide a reference for the followup maintenance of gate.Although the IG-SFPA-BP model has a good performance for the identification of the safety level of hydraulic steel gates,the number of samples collected is small,and some samples have vacancy characteristics.Therefore,the identification accuracy of the model has a large space for improvement,and the sample data set needs to be further improved. Further research is needed to determine the number of hidden layer neurons in the BP neural network.
To prevent accidents caused by the hidden danger of hydraulic steel gates and to avoid the waste of manpower and material resources in overhaul and maintenance process,it is necessary to evaluate the safety grade of the hydraulic steel gate.At present,there are many models for the safety grade evaluation of hydraulic steel gates at home and abroad,but most of them are only applicable to the traditional periodic inspection,while few models for online safety grade evaluation system .The hydraulic steel gate safety ratings can be abstracted as a pattern recognition problem,and the BP neural network is widely used in various fields of pattern recognition because of the strong learning ability,ability to adapt,and fault tolerance.Thus BP neural network can be constructed for the security level of hydraulic steel gate recognition model.Therefore,exploring the neural network for the safety of hydraulic steel gate online evaluation system is feasible.There are too many evaluation indexes of the traditional hydraulic steel gate safety grade,which leads to the redundancy of the input feature vector dimension.Moreover,if the initial value of the BP neural network is not good,it is easy to cause the training result to fall into the local optimal.So,the accuracy of BP neural network for the identification of the safety grade of hydraulic steel gates is not ideal. Since the information gain (IG) can achieve the quantification of the safety level of hydraulic steel gate and the correlation between each feature.The self-adaptive flower pollination algorithm (SFPA) has a strong global search ability and a local search ability and can realize the optimization of the initial value of BP neural network.Given this,an IG-SPAF-BP neural network model is proposed.According to the change of entropy,the information gain of each hydraulic steel gate safety grade feature is calculated,and the features carrying more information are selected as the input features of the neural network to reduce the training time of the neural network and improve the generalization ability of the neural network.By using the global and local pollination of the SFPA algorithm,the initial weight and initial threshold of the BP neural network are optimized to further improve the convergence speed of the BP neural network and the identification accuracy of the safety grade of the hydraulic steel gate. The repeated operation results of the IG-SFPA-BP network model,the standard BP network model,the IGBP network model,the IG-FPA-BP network model,the IG-GA-BP network model,and the IG-PSO-BP network model on the hydraulic steel gate sample set were compared.The experimental results show that in the above five kinds of models,the average recognition accuracy of the IG-SFPA-BP network model is the highest.However,the average running time of the IG-SFPA-BP network model is longer than that of the standard BP network model,IGBP network model,and IG-GA-BP network model,and compared with IG-GA-BP network model and IG-PSO-BP network running time is shorter.Besides,the mean square error of the IG-SFPA-BP network model is the smallest and the error curve is the most stable. The information gain theory reduces the dimension of the feature vector for the identification of the safety grade of hydraulic steel gate,shortening the running time of BP network and improving the classification ability of the network to a certain extent.SPFA algorithm can significantly improve the accuracy of the BP neural network in identifying the safety level of the hydraulic steel gate.IG-SFPA-BP model has good applicability for the identification of the safety grade of the hydraulic steel gate.According to the comparative test,its learning ability,generalization ability,and stability are better than those of standard BP,IG-BP,IG-FPA-BP,IG-GA-BP,and IG-PSO-BP network models.It can provide algorithm support for an online evaluation system of safety grade of hydraulic steel gate,and provide a reference for the followup maintenance of gate.Although the IG-SFPA-BP model has a good performance for the identification of the safety level of hydraulic steel gates,the number of samples collected is small,and some samples have vacancy characteristics.Therefore,the identification accuracy of the model has a large space for improvement,and the sample data set needs to be further improved. Further research is needed to determine the number of hidden layer neurons in the BP neural network.
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