Volume 20,Issue 4,2022 Table of Contents
2022, 20(4):625-630.
Abstract:
Yangtze River is not only the largest river in China, but also the most important water source in China. Protecting the Yangtze River is the basis for the high-quality development of the Yangtze River economic belt. Starting from the analysis of the ecological and environmental problems of Yangtze River, the achievements made in the implementation of the great protection of Yangtze River in the past six years are summarized, the deep-seated problems existing in the ecological environment, scientific solutions and management countermeasures are discussed，and comprehensive countermeasures and suggestions for the protec- tion of Yangtze River in the future are put forward. The analysis shows that the river water quality of Yangtze River has im- proved significantly, but the recovery of lake water quality and ecosystem is slow. The restoration of rare and endemic species, the restoration of water ecosystem integrity and the control of watershed non-point source pollution are long-term and complex tasks. Under the dual influence of climate change and human activities，the evolution mechanism and restoration technology of Yangtze River ecosystem? the joint regulation method of hydraulic engineering groups with full consideration of ecological needs, the development of comprehensive monitoring and digital twin technology of the river basin,and the improvement of vari- ous mechanisms of Yangtze River protection are the focus of future scientific research and river basin protection. Only through comprehensive observation, systematic scientific research and adaptive management measures?the goal for both high-quality de- velopment o￡ Yangtze River economic belt and beautiful China can be achieved.
Yangtze River is not only the largest river in China, but also the most important water source in China. Protecting the Yangtze River is the basis for the high-quality development of the Yangtze River economic belt. Starting from the analysis of the ecological and environmental problems of Yangtze River, the achievements made in the implementation of the great protection of Yangtze River in the past six years are summarized, the deep-seated problems existing in the ecological environment, scientific solutions and management countermeasures are discussed，and comprehensive countermeasures and suggestions for the protec- tion of Yangtze River in the future are put forward. The analysis shows that the river water quality of Yangtze River has im- proved significantly, but the recovery of lake water quality and ecosystem is slow. The restoration of rare and endemic species, the restoration of water ecosystem integrity and the control of watershed non-point source pollution are long-term and complex tasks. Under the dual influence of climate change and human activities，the evolution mechanism and restoration technology of Yangtze River ecosystem? the joint regulation method of hydraulic engineering groups with full consideration of ecological needs, the development of comprehensive monitoring and digital twin technology of the river basin,and the improvement of vari- ous mechanisms of Yangtze River protection are the focus of future scientific research and river basin protection. Only through comprehensive observation, systematic scientific research and adaptive management measures?the goal for both high-quality de- velopment o￡ Yangtze River economic belt and beautiful China can be achieved.
2022, 20(4):631-642.
Abstract:
Current three-level water resources carrying capacity analysis method is not accurate enough to calculate the comprehensive water use efficiency,which is greatly affected by agriculture due to its high-proportion of water use and low water use efficiency.It is difficult to truly reflect the water use efficiency changes of other high-efficiency industries.Under such mode of analysis,It is highly possible that water for agriculture is occupied by other industries,which is not in line with the principle of " water dominates land " and relevant policies for food safety.Therefore,in order to guarantee agricultural water demand and more accurately describe the water use efficiency changes in light of the characteristics of regional industries,agricultural water demand is analyzed separately,thus the bearable economic scale is figured out by water consumption per unit added value of secondary and tertiary industries and the available water resources with deduction of agricultural water demand.Further derivation of the calculation formula simplifies the calculation process,eliminates the need for checking and iterative calculation,and improves the accuracy of results.Through the formula and adjustment of parameters,the influence of regional industrial characteristics on carrying capacity can be reflected more accurately. In the case study of Ningxia Hui Autonomous Region,which has a high proportion of agricultural water consumption,the water use efficiency and industrial proportion were confirmed for calculation of water carrying capacity by two carrying levels of comprehensive well-off society and basic modernization.The population and economic scale that regional water resources can support in different carrying levels were calculated by the original method and improved method respectively.The results showed that the bearable population decreased by the improved method,while basically remained unchanged by the original method.The reason was that the agricultural water demand did not change in the calculation of the improved method,while the original method reduced the agricultural water consumption with the improvement of comprehensive efficiency,transferred it to other industries with higher added value,and improved the carrying economic scale and population.However,it brought about the problem of whether the agricultural water could be effectively guaranteed.The results showed that the agricultural water use efficiency changed with the overall economic levels and lacked of mechanism of decision-making conditions in the original three-level analysis method.The improved method could take the impact of the change of agricultural water use into account,adapt to the analysis and calculation under the rigid constraints of water resources and the principle of "water dominates development ".It proved that the impact of agricultural water on bearing capacity was more accurate and the result was more reasonable,through the comparison of different boundary of agricultural water demand. The formula for directly solving the regional bearable population was deduced to avoid the iteration calculation.Effect of the major factors on water carrying capacity of this method was figured out by adjusting the three variables of agricultural water consumption,GDP per capita and industrial water efficiency.When the agricultural water withholding was gradually reduced,the carrying population and GDP showed a straight increasing trend.When GDP per capita increased gradually,the regional carrying population decreased,while the carrying GDP increased.When the comprehensive water efficiency of the secondary and tertiary industries was gradually improved,the regional carrying population and GDP showed an exponential upward trend.The analysis shows that in order to achieve the planned population target and living standard,it is necessary to reduce agricultural water consumption and improve the water efficiency of secondary and tertiary industries under the condition of rapid growth of per capita GDP.If agricultural water consumption and water efficiency of secondary and tertiary industries are limited,economic development speed should be limited.
Current three-level water resources carrying capacity analysis method is not accurate enough to calculate the comprehensive water use efficiency,which is greatly affected by agriculture due to its high-proportion of water use and low water use efficiency.It is difficult to truly reflect the water use efficiency changes of other high-efficiency industries.Under such mode of analysis,It is highly possible that water for agriculture is occupied by other industries,which is not in line with the principle of " water dominates land " and relevant policies for food safety.Therefore,in order to guarantee agricultural water demand and more accurately describe the water use efficiency changes in light of the characteristics of regional industries,agricultural water demand is analyzed separately,thus the bearable economic scale is figured out by water consumption per unit added value of secondary and tertiary industries and the available water resources with deduction of agricultural water demand.Further derivation of the calculation formula simplifies the calculation process,eliminates the need for checking and iterative calculation,and improves the accuracy of results.Through the formula and adjustment of parameters,the influence of regional industrial characteristics on carrying capacity can be reflected more accurately. In the case study of Ningxia Hui Autonomous Region,which has a high proportion of agricultural water consumption,the water use efficiency and industrial proportion were confirmed for calculation of water carrying capacity by two carrying levels of comprehensive well-off society and basic modernization.The population and economic scale that regional water resources can support in different carrying levels were calculated by the original method and improved method respectively.The results showed that the bearable population decreased by the improved method,while basically remained unchanged by the original method.The reason was that the agricultural water demand did not change in the calculation of the improved method,while the original method reduced the agricultural water consumption with the improvement of comprehensive efficiency,transferred it to other industries with higher added value,and improved the carrying economic scale and population.However,it brought about the problem of whether the agricultural water could be effectively guaranteed.The results showed that the agricultural water use efficiency changed with the overall economic levels and lacked of mechanism of decision-making conditions in the original three-level analysis method.The improved method could take the impact of the change of agricultural water use into account,adapt to the analysis and calculation under the rigid constraints of water resources and the principle of "water dominates development ".It proved that the impact of agricultural water on bearing capacity was more accurate and the result was more reasonable,through the comparison of different boundary of agricultural water demand. The formula for directly solving the regional bearable population was deduced to avoid the iteration calculation.Effect of the major factors on water carrying capacity of this method was figured out by adjusting the three variables of agricultural water consumption,GDP per capita and industrial water efficiency.When the agricultural water withholding was gradually reduced,the carrying population and GDP showed a straight increasing trend.When GDP per capita increased gradually,the regional carrying population decreased,while the carrying GDP increased.When the comprehensive water efficiency of the secondary and tertiary industries was gradually improved,the regional carrying population and GDP showed an exponential upward trend.The analysis shows that in order to achieve the planned population target and living standard,it is necessary to reduce agricultural water consumption and improve the water efficiency of secondary and tertiary industries under the condition of rapid growth of per capita GDP.If agricultural water consumption and water efficiency of secondary and tertiary industries are limited,economic development speed should be limited.
3 Variation characteristics and influencing factors of open-water evaporation in Danjiangkou Reservoir
2022, 20(4):643-649,723.
Abstract:
The Middle Route of the South-to-North Water Transfer Project is the longest cross-basin water transfer project in the world,which undertakes the task of providing water for nearly 80 million people in north China.The Danjiangkou Reservoir,located in the middle reach of the Hanjiang River,is the water source area of the water transfer project.At present,it remains unclear how much water is evaporated from the reservoir each year.To fill this gap,the Penman method and the remote sensing reservoir surface area were used to estimate the evaporation loss of the Danjiangkou Reservoir from 2000 to 2020.An equilibrium temperature method was used to account for the effect of heat storage change on water evaporation estimation.Water evaporation estimates from the Penman model were validated at the site and whole-reservoir scales.At the two scales,pan evaporation observations were used as benchmark data.The contribution of different meteorological variables (temperature,net radiation,relative humidity,and wind speed) to the trend in annual evaporation was quantified based on a detrending experiment.The difference in the annual evaporation trend calculated by the original and detrended specific meteorological variables can be attributed to the effect of the change in this meteorological variable.The results showed that temperature,net radiation,and wind speed in the reservoir showed a significant (p<0.05) upward trend during the study period,while the relative humidity showed an insignificant (p>0.05) downward trend.Changes in these meteorological variables are all conducive to the increase of water evaporation.The remote sensing reservoir area also showed a significant (p<0.05) increasing trend,and the increasing trend was more pronounced after 2015 due to the heightening of the dam.Also,the intra-annual fluctuation of the reservoir surface area during the period 2015-2020 is remarkably smaller than that during the period 2000-2014 because of the implementation of the water transfer project.The evaporation validation results confirmed that the Penman model can be used as a reliable tool to simulate water evaporation loss of the reservoir.It can well reproduce the temporal variability of the reference evaporation at both the site and whole reservoir scales.Annual evaporative loss of the reservoir simulated by the Penman model showed a significant (p<0.05) increasing trend from 2000 to 2020,with a trend value of 3.4×10-3km3/a.The mean annual evaporation loss of the reservoir was 0.26 km3/a,accounting for 2.7% of the planned annual water transfer (9.5 km3).However,actual annual water transfer was far lower than the planned annual water transfer (it was 6.3 km3/a during the first seven years of operation of the water transfer project).Annual evaporation loss during this period accounts for 4.8% of the actual water transfer.In the future,the amount of evaporation loss from the reservoir is likely to further increase with climate warming.Among the four meteorological variables,the net radiation change contributed the most to the trend of the reservoir′s annual evaporation (72.0%),followed by the changes in temperature (23.6%),relative humidity (2.7%),and wind speed (1.7%).The findings of this study can provide references for the water resources management and planning of the middle route of the South-to-North Water Transfer Project.
The Middle Route of the South-to-North Water Transfer Project is the longest cross-basin water transfer project in the world,which undertakes the task of providing water for nearly 80 million people in north China.The Danjiangkou Reservoir,located in the middle reach of the Hanjiang River,is the water source area of the water transfer project.At present,it remains unclear how much water is evaporated from the reservoir each year.To fill this gap,the Penman method and the remote sensing reservoir surface area were used to estimate the evaporation loss of the Danjiangkou Reservoir from 2000 to 2020.An equilibrium temperature method was used to account for the effect of heat storage change on water evaporation estimation.Water evaporation estimates from the Penman model were validated at the site and whole-reservoir scales.At the two scales,pan evaporation observations were used as benchmark data.The contribution of different meteorological variables (temperature,net radiation,relative humidity,and wind speed) to the trend in annual evaporation was quantified based on a detrending experiment.The difference in the annual evaporation trend calculated by the original and detrended specific meteorological variables can be attributed to the effect of the change in this meteorological variable.The results showed that temperature,net radiation,and wind speed in the reservoir showed a significant (p<0.05) upward trend during the study period,while the relative humidity showed an insignificant (p>0.05) downward trend.Changes in these meteorological variables are all conducive to the increase of water evaporation.The remote sensing reservoir area also showed a significant (p<0.05) increasing trend,and the increasing trend was more pronounced after 2015 due to the heightening of the dam.Also,the intra-annual fluctuation of the reservoir surface area during the period 2015-2020 is remarkably smaller than that during the period 2000-2014 because of the implementation of the water transfer project.The evaporation validation results confirmed that the Penman model can be used as a reliable tool to simulate water evaporation loss of the reservoir.It can well reproduce the temporal variability of the reference evaporation at both the site and whole reservoir scales.Annual evaporative loss of the reservoir simulated by the Penman model showed a significant (p<0.05) increasing trend from 2000 to 2020,with a trend value of 3.4×10-3km3/a.The mean annual evaporation loss of the reservoir was 0.26 km3/a,accounting for 2.7% of the planned annual water transfer (9.5 km3).However,actual annual water transfer was far lower than the planned annual water transfer (it was 6.3 km3/a during the first seven years of operation of the water transfer project).Annual evaporation loss during this period accounts for 4.8% of the actual water transfer.In the future,the amount of evaporation loss from the reservoir is likely to further increase with climate warming.Among the four meteorological variables,the net radiation change contributed the most to the trend of the reservoir′s annual evaporation (72.0%),followed by the changes in temperature (23.6%),relative humidity (2.7%),and wind speed (1.7%).The findings of this study can provide references for the water resources management and planning of the middle route of the South-to-North Water Transfer Project.
2022, 20(4):650-659.
Abstract:
Data hydrology,led by the data-intensive research paradigm,is becoming an important research direction of hydrology.Deep learning,which performs well in extracting information from big data,has contributed significantly to the advancement of data-driven hydrological forecasting in recent years.It is continuously integrated with hydrology and becomes an indispensable tool in data hydrology.From a transdisciplinary view,the principle and structure of deep learning models commonly used in hydrology and the general workflow when applying them in hydrological forecasting are introduced.In addition,several approaches for integrating deep learning with domain knowledge in hydrology are described.A useful reference for researchers who are interested in exploring deep learning on hydrological forecasting provided.
Data hydrology,led by the data-intensive research paradigm,is becoming an important research direction of hydrology.Deep learning,which performs well in extracting information from big data,has contributed significantly to the advancement of data-driven hydrological forecasting in recent years.It is continuously integrated with hydrology and becomes an indispensable tool in data hydrology.From a transdisciplinary view,the principle and structure of deep learning models commonly used in hydrology and the general workflow when applying them in hydrological forecasting are introduced.In addition,several approaches for integrating deep learning with domain knowledge in hydrology are described.A useful reference for researchers who are interested in exploring deep learning on hydrological forecasting provided.
2022, 20(4):660-669,747.
Abstract:
The problem of unbalanced and inadequate development among resource,ecology and economic systems in the Yellow River basin is becoming more and more prominent.Quantitative evaluation of the harmonious development level and analysis of the coupling and coordination relationship among them are of great significance to the high-quality development of the Yellow River basin.The 15 prefecture-level administrative regions in the Henan section of the Yellow River are taken as the research area and an evaluation indicator system from the three aspects of resources,ecology and economy is constructs based on the panel data of each region from 2008 to 2019.The combined weight model of AHP-entropy based on least square method is adopted to determine the weight of each indicator.It uses "SMI-P" evaluation method to evaluate the harmonious development level of resource-ecology-economy system.The "SMI-P" method is further combined with the coupling coordination model to comprehensively appraise the coupling coordination relation of resource-ecology-economy system in the study area.The results show that between 2008 and 2019：The harmonious development level of the fifteen prefecture-level administrative regions shows a trend of fluctuating growth on the whole,but none of them reached the "harmony" stage,and among them,Zhengzhou is the best (0.68),and Puyang is the worst (0.51);The coupling coordination relation of the fifteen prefecture-level administrative regions is gradually gathering to the stage of high-quality coordination,but most of them are still in the intermediate and good coordination stage,and the coordinated development speed of Puyang is relatively backward among them.
The problem of unbalanced and inadequate development among resource,ecology and economic systems in the Yellow River basin is becoming more and more prominent.Quantitative evaluation of the harmonious development level and analysis of the coupling and coordination relationship among them are of great significance to the high-quality development of the Yellow River basin.The 15 prefecture-level administrative regions in the Henan section of the Yellow River are taken as the research area and an evaluation indicator system from the three aspects of resources,ecology and economy is constructs based on the panel data of each region from 2008 to 2019.The combined weight model of AHP-entropy based on least square method is adopted to determine the weight of each indicator.It uses "SMI-P" evaluation method to evaluate the harmonious development level of resource-ecology-economy system.The "SMI-P" method is further combined with the coupling coordination model to comprehensively appraise the coupling coordination relation of resource-ecology-economy system in the study area.The results show that between 2008 and 2019：The harmonious development level of the fifteen prefecture-level administrative regions shows a trend of fluctuating growth on the whole,but none of them reached the "harmony" stage,and among them,Zhengzhou is the best (0.68),and Puyang is the worst (0.51);The coupling coordination relation of the fifteen prefecture-level administrative regions is gradually gathering to the stage of high-quality coordination,but most of them are still in the intermediate and good coordination stage,and the coordinated development speed of Puyang is relatively backward among them.
6 Risk assessment of river-type water source areas based on an improved fuzzy comprehensive evaluation
2022, 20(4):670-681.
Abstract:
River-type water source area is an important ecological environment foundation that can provide abundant and clean water sources for the normal work and operation of cities,which simultaneously is threatened by various risk sources with the advancement of urbanization and the continuous development of society.Therefore,all possible influencing factors should be considered when evaluating the risk of river-type water source areas. A risk assessment index system of river-type water source areas was constructed including twenty-two indicators from the four aspects of water pollution,water shortage,ecological environment,and management protection with the aid of the Pressure-State-Response model based on principles of comprehensiveness,practicability,maneuverability,and identifying potential risk sources,understanding the connotation of risks of water source areas and risk identification methods to scientifically assess the risk level of river-type water source areas and effectively ensure the safety of river-type water source areas.Further,the corresponding index risk threshold was analyzed and determined to achieve quantitative or qualitative expression.The weight of indicators was assigned and calculated by the combination weighting method of entropy weight and the analytic hierarchy process.Based on the fuzzy comprehensive evaluation theory,the traditional fuzzy comprehensive evaluation model was improved according to the validity degree principle and weighted average principle,and an improved fuzzy comprehensive evaluation model of rivertype water source areas was established,which fully considered the role of all index membership,reduced the error,and enhanced the scientificity and objectivity of evaluating risk levels. Taking the Zihuizhou water source area of the Yangtze River in Nanjing as an example,the improved fuzzy comprehensive evaluation method was used to quantitatively evaluate the risk status of land and water area in the 20 km buffer zone outside the quasi-protection area of Zihuizhou water source area in 2019.The calculated results showed that the comprehensive risk assessment result of Zihuizhou water source area was 0.216 7,which belonged to the lower risk level.Specifically,the risk of water pollution was at the lower risk level,the risk of water shortage was at the lowrisk level,the risk of ecological environment was at the lower risk level,and the risk of management and protection was at the lowrisk level.Among these four aspects,the risk to the ecological environment was the most obvious,and the investment in environmental protection should be continuously increased to provide a practical guarantee for the ecological environment around the water source area.Overall,the construction and management of the Zihuizhou water source area of the Yangtze River were good,and the calculated results were consistent with the actual situation,which had high reliability. The risk assessment index system can comprehensively evaluate the risk of rivertype water source areas from four aspects:water pollution,water shortage,ecological environment and management and protection.The validity degree principle and the weighted average principle were used to improve the traditional fuzzy comprehensive evaluation model for assessing the risk of river-type water source areas.The risk assessment results in Zihuizhou water source area of the Yangtze River were determined to be at the lower risk level,and the overall management was good.It can be concluded that the existing hidden dangers were mainly the risk factors such as the close distribution of dock enterprises and low vegetation coverage in Zihuizhou water source area,and there was a great space for progress in ecological environment risk control.The risk level of Zihuizhou water source can be descended through risk control measures such as the construction of industrial and domestic sewage treatment projects,timely investigation of sudden water pollution accidents,and construction of ecological environment protection projects.
River-type water source area is an important ecological environment foundation that can provide abundant and clean water sources for the normal work and operation of cities,which simultaneously is threatened by various risk sources with the advancement of urbanization and the continuous development of society.Therefore,all possible influencing factors should be considered when evaluating the risk of river-type water source areas. A risk assessment index system of river-type water source areas was constructed including twenty-two indicators from the four aspects of water pollution,water shortage,ecological environment,and management protection with the aid of the Pressure-State-Response model based on principles of comprehensiveness,practicability,maneuverability,and identifying potential risk sources,understanding the connotation of risks of water source areas and risk identification methods to scientifically assess the risk level of river-type water source areas and effectively ensure the safety of river-type water source areas.Further,the corresponding index risk threshold was analyzed and determined to achieve quantitative or qualitative expression.The weight of indicators was assigned and calculated by the combination weighting method of entropy weight and the analytic hierarchy process.Based on the fuzzy comprehensive evaluation theory,the traditional fuzzy comprehensive evaluation model was improved according to the validity degree principle and weighted average principle,and an improved fuzzy comprehensive evaluation model of rivertype water source areas was established,which fully considered the role of all index membership,reduced the error,and enhanced the scientificity and objectivity of evaluating risk levels. Taking the Zihuizhou water source area of the Yangtze River in Nanjing as an example,the improved fuzzy comprehensive evaluation method was used to quantitatively evaluate the risk status of land and water area in the 20 km buffer zone outside the quasi-protection area of Zihuizhou water source area in 2019.The calculated results showed that the comprehensive risk assessment result of Zihuizhou water source area was 0.216 7,which belonged to the lower risk level.Specifically,the risk of water pollution was at the lower risk level,the risk of water shortage was at the lowrisk level,the risk of ecological environment was at the lower risk level,and the risk of management and protection was at the lowrisk level.Among these four aspects,the risk to the ecological environment was the most obvious,and the investment in environmental protection should be continuously increased to provide a practical guarantee for the ecological environment around the water source area.Overall,the construction and management of the Zihuizhou water source area of the Yangtze River were good,and the calculated results were consistent with the actual situation,which had high reliability. The risk assessment index system can comprehensively evaluate the risk of rivertype water source areas from four aspects:water pollution,water shortage,ecological environment and management and protection.The validity degree principle and the weighted average principle were used to improve the traditional fuzzy comprehensive evaluation model for assessing the risk of river-type water source areas.The risk assessment results in Zihuizhou water source area of the Yangtze River were determined to be at the lower risk level,and the overall management was good.It can be concluded that the existing hidden dangers were mainly the risk factors such as the close distribution of dock enterprises and low vegetation coverage in Zihuizhou water source area,and there was a great space for progress in ecological environment risk control.The risk level of Zihuizhou water source can be descended through risk control measures such as the construction of industrial and domestic sewage treatment projects,timely investigation of sudden water pollution accidents,and construction of ecological environment protection projects.
2022, 20(4):682-690.
Abstract:
Suzhou is a typical economically developed city in southern Jiangsu.With the rapid economic development,the consumption of water resources is also very large,and the resulting discharge of a large number of industrial and domestic sewage leads to a serious water shortage.Strengthening the utilization of reclaimed water plays a very important role in alleviating the contradiction between supply and demand of urban water resources and improving water pollution,which is conducive to realizing the sustainable utilization of water resources. In order to further improve the utilization rate of reclaimed water in Suzhou,form an advanced and suitable model of reclaimed water utilization and promote the development of reclaimed water enterprise,the present situation of sewage treatment is analyzed and water utilization capacity is reclaimed in Suzhou.Selected 25 factors affecting the amount of reclaimed water resources,and based on the relevant statistical data from 2008 to 2020,a BP neural network model was constructed to obtain the weight matrix between input value and output value.It replaced the direct correlation matrix obtained by questionnaire survey or expert scoring in the traditional DEMATEL model.The key driving factors and characteristic factors which affect the development of reclaimed water utilization in Suzhou were identified.On this basis, the GM (1,N) grey prediction model is established,and the historical data of identified key factors and their extended data were taken as the data of relevant factors to predict the potential of reclaimed water utilization in Suzhou. The results show that:investment in sewage treatment and drainage facilities,water consumption of households,total annual water resources and water consumption of 10 thousand RMB GDP were the key driving factors,which were the main factors affecting the development of reclaimed water utilization in Suzhou;sewage discharge,the amount and capacity of sewage treatment,and urban water consumption population were the key characteristic factors,which had a direct impact on the development of reclaimed water utilization in Suzhou.Therefore,in order to promote the development of Suzhou city reclaimed water utilization,it is needed to increase investment for sewage treatment,promote the treatment scale and technology level,on the other hand to increase drainage facilities investment,improve the urban sewage collection pipe network,increase the rate of sewerage,perfect supporting facilities,improve reclaimed water pipe network coverage.To make renewable water resources have more reasonable allocation，GM (1,N) prediction model basically met all kinds of tests and could be used for medium and long term prediction of reclaimed water consumption.The average relative error was 0.22%,and the maximum error was 6.55%.By 2025,the utilization potential of reclaimed water in Suzhou can reach 596.305 2 million m3,which had a huge space for improvement compared with the current utilization level.
Suzhou is a typical economically developed city in southern Jiangsu.With the rapid economic development,the consumption of water resources is also very large,and the resulting discharge of a large number of industrial and domestic sewage leads to a serious water shortage.Strengthening the utilization of reclaimed water plays a very important role in alleviating the contradiction between supply and demand of urban water resources and improving water pollution,which is conducive to realizing the sustainable utilization of water resources. In order to further improve the utilization rate of reclaimed water in Suzhou,form an advanced and suitable model of reclaimed water utilization and promote the development of reclaimed water enterprise,the present situation of sewage treatment is analyzed and water utilization capacity is reclaimed in Suzhou.Selected 25 factors affecting the amount of reclaimed water resources,and based on the relevant statistical data from 2008 to 2020,a BP neural network model was constructed to obtain the weight matrix between input value and output value.It replaced the direct correlation matrix obtained by questionnaire survey or expert scoring in the traditional DEMATEL model.The key driving factors and characteristic factors which affect the development of reclaimed water utilization in Suzhou were identified.On this basis, the GM (1,N) grey prediction model is established,and the historical data of identified key factors and their extended data were taken as the data of relevant factors to predict the potential of reclaimed water utilization in Suzhou. The results show that:investment in sewage treatment and drainage facilities,water consumption of households,total annual water resources and water consumption of 10 thousand RMB GDP were the key driving factors,which were the main factors affecting the development of reclaimed water utilization in Suzhou;sewage discharge,the amount and capacity of sewage treatment,and urban water consumption population were the key characteristic factors,which had a direct impact on the development of reclaimed water utilization in Suzhou.Therefore,in order to promote the development of Suzhou city reclaimed water utilization,it is needed to increase investment for sewage treatment,promote the treatment scale and technology level,on the other hand to increase drainage facilities investment,improve the urban sewage collection pipe network,increase the rate of sewerage,perfect supporting facilities,improve reclaimed water pipe network coverage.To make renewable water resources have more reasonable allocation，GM (1,N) prediction model basically met all kinds of tests and could be used for medium and long term prediction of reclaimed water consumption.The average relative error was 0.22%,and the maximum error was 6.55%.By 2025,the utilization potential of reclaimed water in Suzhou can reach 596.305 2 million m3,which had a huge space for improvement compared with the current utilization level.
2022, 20(4):691-702.
Abstract:
In order to give guidelines for the execution of countermeasures in response to extreme precipitation events.the tempo-spatial variation characteristics of extreme precipitationare are analyzed by 11 extreme precipitation indexes during the past 60 years (1955-2015) in Shijiazhuang City.The results showed that the extreme precipitation of Shijiazhuang City generally showed a downward trend in the past 60 years,and the wet day precipitation (PRCPTOT) exhibited the most obvious downward trend.There were significant spatial differences in the trend of extreme precipitation indexes.According to the spatial superposition of the historical trend of extreme precipitation index and Hurst index,the extreme precipitation intensity indexes in most areas of Shijiazhuang city will continue to decline in the future,and the extreme precipitation intensity indexes in some central areas will continue to rise.
In order to give guidelines for the execution of countermeasures in response to extreme precipitation events.the tempo-spatial variation characteristics of extreme precipitationare are analyzed by 11 extreme precipitation indexes during the past 60 years (1955-2015) in Shijiazhuang City.The results showed that the extreme precipitation of Shijiazhuang City generally showed a downward trend in the past 60 years,and the wet day precipitation (PRCPTOT) exhibited the most obvious downward trend.There were significant spatial differences in the trend of extreme precipitation indexes.According to the spatial superposition of the historical trend of extreme precipitation index and Hurst index,the extreme precipitation intensity indexes in most areas of Shijiazhuang city will continue to decline in the future,and the extreme precipitation intensity indexes in some central areas will continue to rise.
2022, 20(4):703-713.
Abstract:
With the intensification of global climate change,the contradiction between supply and demand of water resources was becoming increasingly tense.The water resources of Hotan Oasis located inland mainly came from the upstream mountainous areas,the change of mountain runoff will directly affected social and economic activities.This area was mainly prospered by Hotan River,the change of Hotan River runoff was very important for the stable development of the oasis,and will also had an important impact on the water supply and ecological environment of Tarim River below the basin.Therefore,it was of great practical significance to study the runoff change of Hotan River under changing environment.Based on the analysis of the impact of climate change on the runoff of Hotan River,the Soil and Water Assessment Tool（SWAT） model was used to simulate the runoff in the upper reaches of Hotan River basin,and simulated the runoff in the future scenario.The trend of temperature and precipitation were increased,and the variation rates of annual temperature and precipitation were 0.31 C/10 a and 16.5 mm/10 a,respectively.The runoff was also increased over the period of 1980-2015.The annual runoff of Hotan River generally showed an upward trend from 1980 to 2015.Especially since the beginning of the 21st century,with the increase of temperature,the acceleration of glacier snow melting and the increase of precipitation led to the increase of runoff of Hotan River.In particular,the annual average temperature had increased significantly since 2002 and the average annual precipitation had not increased significantly since 2004,which exacerbated the increasing trend of runoff.The SWAT model was used to simulate the runoff in the upper reaches of Hotan River.The results showed that it has good applicability in the upper reaches of Hotan River.Taking 2009-2011 as the base period,if the precipitation in the upper reaches of Hotan River increased by 12.5%,10% and decreased by 10% respectively,the runoff will increased by 8.19%,6.45% and decreased by 6.23% respectively;If the temperature of Hotan upstream watershed increased by 0.3 ℃,1 ℃ and 2 ℃ respectively,the runoff of Hotan River will increased by 1.96%,7.74% and 12.99% respectively.The runoff was generally predicted to increase in all six scenarios,with the lowest runoff (5.125 billion m3/a) in HADG_RCP 8.5 scenario in 2021-2030 and the lowest runoff (5.306 billion m3/a) in BCC_RCP 4.5 scenario in 2031-2040.The results could provide decision-making basis for water resources allocation and management in Hotan Oasis in the future.
With the intensification of global climate change,the contradiction between supply and demand of water resources was becoming increasingly tense.The water resources of Hotan Oasis located inland mainly came from the upstream mountainous areas,the change of mountain runoff will directly affected social and economic activities.This area was mainly prospered by Hotan River,the change of Hotan River runoff was very important for the stable development of the oasis,and will also had an important impact on the water supply and ecological environment of Tarim River below the basin.Therefore,it was of great practical significance to study the runoff change of Hotan River under changing environment.Based on the analysis of the impact of climate change on the runoff of Hotan River,the Soil and Water Assessment Tool（SWAT） model was used to simulate the runoff in the upper reaches of Hotan River basin,and simulated the runoff in the future scenario.The trend of temperature and precipitation were increased,and the variation rates of annual temperature and precipitation were 0.31 C/10 a and 16.5 mm/10 a,respectively.The runoff was also increased over the period of 1980-2015.The annual runoff of Hotan River generally showed an upward trend from 1980 to 2015.Especially since the beginning of the 21st century,with the increase of temperature,the acceleration of glacier snow melting and the increase of precipitation led to the increase of runoff of Hotan River.In particular,the annual average temperature had increased significantly since 2002 and the average annual precipitation had not increased significantly since 2004,which exacerbated the increasing trend of runoff.The SWAT model was used to simulate the runoff in the upper reaches of Hotan River.The results showed that it has good applicability in the upper reaches of Hotan River.Taking 2009-2011 as the base period,if the precipitation in the upper reaches of Hotan River increased by 12.5%,10% and decreased by 10% respectively,the runoff will increased by 8.19%,6.45% and decreased by 6.23% respectively;If the temperature of Hotan upstream watershed increased by 0.3 ℃,1 ℃ and 2 ℃ respectively,the runoff of Hotan River will increased by 1.96%,7.74% and 12.99% respectively.The runoff was generally predicted to increase in all six scenarios,with the lowest runoff (5.125 billion m3/a) in HADG_RCP 8.5 scenario in 2021-2030 and the lowest runoff (5.306 billion m3/a) in BCC_RCP 4.5 scenario in 2031-2040.The results could provide decision-making basis for water resources allocation and management in Hotan Oasis in the future.
10 Spatial-temporal variation of water environment carrying capacity in the Yangtze River Economic Belt
2022, 20(4):714-723.
Abstract:
Yangtze River Economic Belt (YEB) is one of the important strategic development regions in China which has created more than 2/5 of China′s GDP,but it faces the conflicts between economic development and water environment protection.With the rapid development of economic-society,human activities have more and more impacts on the water environment,therefore it is of great significance to study the water environment carrying capacity (WECC) of this area,in which the spatial-temporal variation of WECC are an important content. In most previous related studies,some method are usually used to determine the grade of WECC.In fact,WECC is a fuzzy concept,and the boundary between two adjacent grades is not clear.Therefore,it is necessary to consider the law of unity of opposites between adjacent grades in the evaluation of WECC.Variable set method is an important uncertainty mathematical theory in the field of water resources system analysis.The variable set method is used to calculate the relative membership degree,and the index based on grade eigenvalue is used to characterize the state of WECC.Focusing on the dual effects of natural background and human activities,the evaluation index system of WECC is constructed from the three subsystems of water resources,ecological environment and economy and society,and a water environment carrying capacity index (WECCI) model is established based on variable set method,and the temporal and spatial variation characteristics of WECC in YEB are discussed. The results show that the WECCI of YEB increased from 4.20 to 6.08,showing a basic trend of increasing year by year;The WECCI in the upper,middle and lower reaches is becoming more and more balanced,the variance decreased by 57.27% from 0.14 to 0.06,but increased slightly in 2018;The constraints have spatial differentiation characteristics;The ecological environment subsystem of upper reaches is relatively weak,but the gap is narrowing year by year;The restriction of water resources subsystem in the middle reaches is becoming more and more prominent;The economic-society subsystem of lower reaches maintains significant advantages all year round,while the water resources subsystem lags behind seriously;In 2018,except Zhejiang,the WECC showed that the upper reaches were better than the middle reaches,and the middle reaches were better than the lower reaches.According to the provinces(manicipalities),Zhejiang,Sichuan,Chongqing,Yunnan,Guizhou,Hunan,Jiangxi,Hubei,Jiangsu,Shanghai and Anhui were ranked from high to low. The WECC of YEB has improved year by year from 2009 to 2018,and has an obvious spatial distribution law;The water resources subsystem has a significant restrictive effect on the improvement of WECC of the current YEB and become one of the main contradictions that need to be paid attention to in the process of improving the WECC of YEB.Analyzing the temporal-spatial variation and main interference factors of WECC of YEB and its region can provide reference for the formulation of sustainable and high-quality development policies of YEB.
Yangtze River Economic Belt (YEB) is one of the important strategic development regions in China which has created more than 2/5 of China′s GDP,but it faces the conflicts between economic development and water environment protection.With the rapid development of economic-society,human activities have more and more impacts on the water environment,therefore it is of great significance to study the water environment carrying capacity (WECC) of this area,in which the spatial-temporal variation of WECC are an important content. In most previous related studies,some method are usually used to determine the grade of WECC.In fact,WECC is a fuzzy concept,and the boundary between two adjacent grades is not clear.Therefore,it is necessary to consider the law of unity of opposites between adjacent grades in the evaluation of WECC.Variable set method is an important uncertainty mathematical theory in the field of water resources system analysis.The variable set method is used to calculate the relative membership degree,and the index based on grade eigenvalue is used to characterize the state of WECC.Focusing on the dual effects of natural background and human activities,the evaluation index system of WECC is constructed from the three subsystems of water resources,ecological environment and economy and society,and a water environment carrying capacity index (WECCI) model is established based on variable set method,and the temporal and spatial variation characteristics of WECC in YEB are discussed. The results show that the WECCI of YEB increased from 4.20 to 6.08,showing a basic trend of increasing year by year;The WECCI in the upper,middle and lower reaches is becoming more and more balanced,the variance decreased by 57.27% from 0.14 to 0.06,but increased slightly in 2018;The constraints have spatial differentiation characteristics;The ecological environment subsystem of upper reaches is relatively weak,but the gap is narrowing year by year;The restriction of water resources subsystem in the middle reaches is becoming more and more prominent;The economic-society subsystem of lower reaches maintains significant advantages all year round,while the water resources subsystem lags behind seriously;In 2018,except Zhejiang,the WECC showed that the upper reaches were better than the middle reaches,and the middle reaches were better than the lower reaches.According to the provinces(manicipalities),Zhejiang,Sichuan,Chongqing,Yunnan,Guizhou,Hunan,Jiangxi,Hubei,Jiangsu,Shanghai and Anhui were ranked from high to low. The WECC of YEB has improved year by year from 2009 to 2018,and has an obvious spatial distribution law;The water resources subsystem has a significant restrictive effect on the improvement of WECC of the current YEB and become one of the main contradictions that need to be paid attention to in the process of improving the WECC of YEB.Analyzing the temporal-spatial variation and main interference factors of WECC of YEB and its region can provide reference for the formulation of sustainable and high-quality development policies of YEB.
2022, 20(4):724-736.
Abstract:
The quantity and spatial distribution of precipitation are changed by the interception of vegetation canopy,and then affect the water cycle of ecosystem.Evaluated canopy interception and its temporal and spatial dynamic changes accurately is of great significance for exploring the process of eco-hydrological cycle and revealing the impact of climate change. Abundant literature analysis is used to deepen the understanding of the interception mechanism.Precipitation characteristics,vegetation physiological characteristics,and meteorological factors affect the canopy interception process.With the continuous precipitation,the canopy interception rate first increased and then decreased.The continuous expansion of vegetation leaf area is conducive to precipitation interception.Wind speed,air temperature,canopy dryness,and other factors can increase additional interception.Precipitation is intercepted variously among different vegetation types.The canopy interception rate of trees is about 30% and that of crops is only about 15%.Precipitation variability is increasing,and the phenological effect of vegetation and land use are also changing,which will deeply affect all links of the water cycle,and then affect the interception of the vegetation canopy.Artificial simulation and indirect observation are used to determine the interception water volume.The artificial simulation method is used to determine the interception water of a few low herbs,shrubs,and crops,and the measurement results are often greater than the actual direct observation.The estimation of interception through the water balance equation is called the indirect observation method,which can well obtain the dynamic change of precipitation interception.The canopy interception model combined with the results of indirect observation can simulate a wider range of canopy interception water.Three canopy interception models have been studied in China.Canopy interception mechanism is one of the emphases of theoretical models,and it requires higher mathematical computing power for researchers.The semi-empirical semi-theoretical model is widely applied because of its fewer parameters and relatively clear physical meaning. Based on the above contents,the research on canopy interception is discussed and prospected:(1) Herbaceous plants play an important role in ecological maintenance and green city construction in arid and plateau areas,so they should be paid more attention;Different canopy interception measurement methods and problems existing in the operation process will lead to great uncertainty in the measured results,and the measurement method can be improved in combination with global scale remote sensing data;The canopy interception model can be coupled with the global environmental change model to enhance the applicability of the model.
The quantity and spatial distribution of precipitation are changed by the interception of vegetation canopy,and then affect the water cycle of ecosystem.Evaluated canopy interception and its temporal and spatial dynamic changes accurately is of great significance for exploring the process of eco-hydrological cycle and revealing the impact of climate change. Abundant literature analysis is used to deepen the understanding of the interception mechanism.Precipitation characteristics,vegetation physiological characteristics,and meteorological factors affect the canopy interception process.With the continuous precipitation,the canopy interception rate first increased and then decreased.The continuous expansion of vegetation leaf area is conducive to precipitation interception.Wind speed,air temperature,canopy dryness,and other factors can increase additional interception.Precipitation is intercepted variously among different vegetation types.The canopy interception rate of trees is about 30% and that of crops is only about 15%.Precipitation variability is increasing,and the phenological effect of vegetation and land use are also changing,which will deeply affect all links of the water cycle,and then affect the interception of the vegetation canopy.Artificial simulation and indirect observation are used to determine the interception water volume.The artificial simulation method is used to determine the interception water of a few low herbs,shrubs,and crops,and the measurement results are often greater than the actual direct observation.The estimation of interception through the water balance equation is called the indirect observation method,which can well obtain the dynamic change of precipitation interception.The canopy interception model combined with the results of indirect observation can simulate a wider range of canopy interception water.Three canopy interception models have been studied in China.Canopy interception mechanism is one of the emphases of theoretical models,and it requires higher mathematical computing power for researchers.The semi-empirical semi-theoretical model is widely applied because of its fewer parameters and relatively clear physical meaning. Based on the above contents,the research on canopy interception is discussed and prospected:(1) Herbaceous plants play an important role in ecological maintenance and green city construction in arid and plateau areas,so they should be paid more attention;Different canopy interception measurement methods and problems existing in the operation process will lead to great uncertainty in the measured results,and the measurement method can be improved in combination with global scale remote sensing data;The canopy interception model can be coupled with the global environmental change model to enhance the applicability of the model.
2022, 20(4):737-747.
Abstract:
In order to explore the characteristics of cover change in Heilongjiang Province under global warming.The spatiotemporal changes and future trends of vegetation cover in Heilongjiang Province in recent 34 years were analyzed based on GIMMS NDVI3G data from 1982 to 2015.At the same time,the correlation between vegetation cover and temperature,precipitation and evapotranspiration were analyzed based on the data of 34 meteorological stations in the province.Research results can provide theoretical support for the study of land-use/cover change in cold regions under the background of climate change. Research methods were trend analysis,Hurst index method and correlation analysis method.Trend analysis method used linear regression analysis to calculate the time-varying variables to determine the significance of the interannual changes in variables,and then used slope to reflect its changing trend.Hurst index method was based on current trends and the range of H value to analyze whether future trends of NDVI was consistent with the current,so as to predict the future trends of NDVI.Correlation analysis method was based on Pearson correlation coefficient to analyze correlations of NDVI with precipitation,mean temperature and evapotranspiration,to study climatic factors influence on NDVI. The results showed that:During 34 years,the three types of planting coverage in Heilongjiang Province all showed a slow upward trend.The growth rate of NDVI in woodland and grassland was 0.004/10 a,and that in farmland was 0.002/10 a.The overall change of vegetation cover increased first and then decreased,with the maximum value appearing in 2014 and the minimum value appearing in 1984.The vegetation cover in Heilongjiang Province is high in the east and low in the west.Taking "Daxing′an mountains-Yichun-Hegang-Jiamusi-Shuangyashan" as the boundary,the vegetation coverage is relatively rich in the southwest,while less in the northeast.The same feature of vegetation change in Heilongjiang Province is stronger than the opposite feature,and areas showed persistence and anti-persistence accounted for 97.65% and 2.35% of total area,respectively.In Heilongjiang Province,the correlation between vegetation cover change and air temperature is higher than that of precipitation,and the correlation between evapotranspiration and vegetation index is significantly different in annual and growing seasons.The average temperature is the main meteorological factor affecting vegetation cover change in the growing season. The overall vegetation cover change in Heilongjiang Province showed a slow increasing trend from 1982 to 2015.The rising trend of NDVI in growing season was more obvious than that in annual average,and there was a good consistency in fluctuation of NDVI between annual average and growing season.The spatial heterogeneity of vegetation cover change was obvious,and most NDVI changes were within ±0.1.Vegetation coverage in Daxing′an mountains increased to a high degree;Vegetation cover change is not obvious in high altitude areas;Reduction of NDVI in the southeast of Sanjiang Plain and some areas of Xiaoxing′anmountains is obvious.In different land use types,woodland in mountainous areas is higher than that in plain farmland and urban areas.During the growing season,NDVI in cropland and grassland showed a significant increasing trend,while NDVI in woodland showed a slight decreasing trend.According to the prediction of the future trend of NDVI change,there were many areas where the future change trend of vegetation cover index showed a good trend,and there were also many areas where the future change was uncertain,and vegetation cover index showed a degeneration phenomenon in the southern region.Regions of uncertain about NDVI future changes were mainly distributed in Songnen Plain,central Region and southern Sanjiang Plain of Heilongjiang Province.In different periods,NDVI future variation trend was obviously different,and the spatial variability was obvious.NDVI future variation trend showed continuous degradation and continuous improvement mainly due to changes in geographic location and climate factors.The positive correlation between NDVI and temperature was weak,and the negative correlation between NDVI and precipitation was weaker,so NDVI response to air temperature is more pronounced.Compared with forest land,cities had weaker self-regulation ability,so NDVI located in cities was more responsive to climate factors.NDVI changes were significantly consistent with changes in air temperature and precipitation in the southwestern urban areas of Heilongjiang Province.About NDVI response to temperature and precipitation,spatial heterogeneity was obvious.Especially in the vegetation growing season,its growth was mostly influenced by precipitation.However,in the Suihua area of Songnen Plain,there was no obvious difference in vegetation cover change affected by temperature and precipitation.
In order to explore the characteristics of cover change in Heilongjiang Province under global warming.The spatiotemporal changes and future trends of vegetation cover in Heilongjiang Province in recent 34 years were analyzed based on GIMMS NDVI3G data from 1982 to 2015.At the same time,the correlation between vegetation cover and temperature,precipitation and evapotranspiration were analyzed based on the data of 34 meteorological stations in the province.Research results can provide theoretical support for the study of land-use/cover change in cold regions under the background of climate change. Research methods were trend analysis,Hurst index method and correlation analysis method.Trend analysis method used linear regression analysis to calculate the time-varying variables to determine the significance of the interannual changes in variables,and then used slope to reflect its changing trend.Hurst index method was based on current trends and the range of H value to analyze whether future trends of NDVI was consistent with the current,so as to predict the future trends of NDVI.Correlation analysis method was based on Pearson correlation coefficient to analyze correlations of NDVI with precipitation,mean temperature and evapotranspiration,to study climatic factors influence on NDVI. The results showed that:During 34 years,the three types of planting coverage in Heilongjiang Province all showed a slow upward trend.The growth rate of NDVI in woodland and grassland was 0.004/10 a,and that in farmland was 0.002/10 a.The overall change of vegetation cover increased first and then decreased,with the maximum value appearing in 2014 and the minimum value appearing in 1984.The vegetation cover in Heilongjiang Province is high in the east and low in the west.Taking "Daxing′an mountains-Yichun-Hegang-Jiamusi-Shuangyashan" as the boundary,the vegetation coverage is relatively rich in the southwest,while less in the northeast.The same feature of vegetation change in Heilongjiang Province is stronger than the opposite feature,and areas showed persistence and anti-persistence accounted for 97.65% and 2.35% of total area,respectively.In Heilongjiang Province,the correlation between vegetation cover change and air temperature is higher than that of precipitation,and the correlation between evapotranspiration and vegetation index is significantly different in annual and growing seasons.The average temperature is the main meteorological factor affecting vegetation cover change in the growing season. The overall vegetation cover change in Heilongjiang Province showed a slow increasing trend from 1982 to 2015.The rising trend of NDVI in growing season was more obvious than that in annual average,and there was a good consistency in fluctuation of NDVI between annual average and growing season.The spatial heterogeneity of vegetation cover change was obvious,and most NDVI changes were within ±0.1.Vegetation coverage in Daxing′an mountains increased to a high degree;Vegetation cover change is not obvious in high altitude areas;Reduction of NDVI in the southeast of Sanjiang Plain and some areas of Xiaoxing′anmountains is obvious.In different land use types,woodland in mountainous areas is higher than that in plain farmland and urban areas.During the growing season,NDVI in cropland and grassland showed a significant increasing trend,while NDVI in woodland showed a slight decreasing trend.According to the prediction of the future trend of NDVI change,there were many areas where the future change trend of vegetation cover index showed a good trend,and there were also many areas where the future change was uncertain,and vegetation cover index showed a degeneration phenomenon in the southern region.Regions of uncertain about NDVI future changes were mainly distributed in Songnen Plain,central Region and southern Sanjiang Plain of Heilongjiang Province.In different periods,NDVI future variation trend was obviously different,and the spatial variability was obvious.NDVI future variation trend showed continuous degradation and continuous improvement mainly due to changes in geographic location and climate factors.The positive correlation between NDVI and temperature was weak,and the negative correlation between NDVI and precipitation was weaker,so NDVI response to air temperature is more pronounced.Compared with forest land,cities had weaker self-regulation ability,so NDVI located in cities was more responsive to climate factors.NDVI changes were significantly consistent with changes in air temperature and precipitation in the southwestern urban areas of Heilongjiang Province.About NDVI response to temperature and precipitation,spatial heterogeneity was obvious.Especially in the vegetation growing season,its growth was mostly influenced by precipitation.However,in the Suihua area of Songnen Plain,there was no obvious difference in vegetation cover change affected by temperature and precipitation.
2022, 20(4):748-756.
Abstract:
The ecological base flow is very important for coordinating the ecological protection and development of rivers.However,the threshold system that can effectively guide the determination of China′s ecological base flow is still lacking.In previous studies,it is generally required that the proportion of river ecological base flow to its multi-year average natural flow (referred to as “ecological base flow proportion”) should not be less than 10%.Considering the different hydrological and ecological conditions in different regions of China,it is difficult to effectively meet the macromanagement needs of China′s ecological flow by adopting a unified threshold standard. Through the analysis of natural and measured hydrological data of 439 sections,a threshold system is proposed for the ecological base flow proportion of rivers distributed in 10 Class I water resources zones and different catchment areas of China (excluding Hong Kong,Macao and Taiwan).The proportion thresholds of ecological base flow are composed of the upper limit,lower limit and recommended values. The results show that:When there is no controlled engineering control,the ecological base flow proportion shows an upward trend with the increase of catchment area.The average recommended values in small,medium and large sections are 4.4%,6.6% and 9.2% respectively in dry season and,9.4%,11.6% and 16.2% respectively in wet season.In terms of large sections with a catchment area of more than 10,000 km2,the recommended value in the dry season in the water resources zones is 9.2% on average.Among them,the highest in the Yellow River,southwestern rivers and northwestern rivers regions,reaching 16%,while the lowest is only 1% ~ 3% in Songliao and Huaihe regions.the average recommended value in the dry season in the water resources zones is 15% under the regulation of water conservancy projects. The proposed threshold values can provide support for the determination of ecological base flow considering different regions,section types,and periods.
The ecological base flow is very important for coordinating the ecological protection and development of rivers.However,the threshold system that can effectively guide the determination of China′s ecological base flow is still lacking.In previous studies,it is generally required that the proportion of river ecological base flow to its multi-year average natural flow (referred to as “ecological base flow proportion”) should not be less than 10%.Considering the different hydrological and ecological conditions in different regions of China,it is difficult to effectively meet the macromanagement needs of China′s ecological flow by adopting a unified threshold standard. Through the analysis of natural and measured hydrological data of 439 sections,a threshold system is proposed for the ecological base flow proportion of rivers distributed in 10 Class I water resources zones and different catchment areas of China (excluding Hong Kong,Macao and Taiwan).The proportion thresholds of ecological base flow are composed of the upper limit,lower limit and recommended values. The results show that:When there is no controlled engineering control,the ecological base flow proportion shows an upward trend with the increase of catchment area.The average recommended values in small,medium and large sections are 4.4%,6.6% and 9.2% respectively in dry season and,9.4%,11.6% and 16.2% respectively in wet season.In terms of large sections with a catchment area of more than 10,000 km2,the recommended value in the dry season in the water resources zones is 9.2% on average.Among them,the highest in the Yellow River,southwestern rivers and northwestern rivers regions,reaching 16%,while the lowest is only 1% ~ 3% in Songliao and Huaihe regions.the average recommended value in the dry season in the water resources zones is 15% under the regulation of water conservancy projects. The proposed threshold values can provide support for the determination of ecological base flow considering different regions,section types,and periods.
2022, 20(4):757-764.
Abstract:
With the rapid development of economics and society,especially with the implementation of “reform and opening up” to the outside world,the industry and urbanization developed very quickly in China.The rapid development of industry resulted in the considerable need for water resources,and the great changes of water cycle among supply,uses,assumption and drainage.It further resulted in the great challenge on water supply,as well as the exacerbation of water quality and deterioration of aquatic ecosystems.On the other hand,rapid urbanization affected the relationship between rivers and lakes,and resulted in fragmentation of rivers and shrinkage even disappearance of lakes.In order to improve the water security,it is quite necessary to construct the national water networks with the capability of adjustment between abundant and dry periods,as well as complementary between western and eastern China.Considering the strategic needs of national water security,the overall layout of national water network was investigated,and the strategic needs of river-lake system connectivity were analyzed.Possible effects of river-lake system connectivity on water resources,flood control,ecological system,environment,society and economics were comprehensively analyzed through multidisciplinary ways.The function and roles of South-North Water Transfer Project in the construction of national water network were also identified.Great efforts have been made to comprehensively analyze the key issues and difficulties in river-lake system connectivity through multidisciplinary and systematic research,so as to provide reference and scientific support for the construction of national water network. From the analysis on the connectivity of river-lake system,it was found that the connection of river-lake system and the construction of national water networks are the most important national strategy to improve water security in China.Major functions and roles of the national water networks mainly focused on the improvement of water resources allocation and water supply,improvement of water quality and aquatic ecosystem,as well as the improvement of capability to mitigate floods and droughts.The objective of connection for rivers and lakes should respect the law of naturalized hydrological cycle and evolution of rivers and lakes,and consider the functions of water resources,environment,and ecology.Through the construction of reservoirs,dams/weirs,pumping stations and channels,national water networks will be constructed at the national,regional and urban scales.The water networks will be characterized with reasonable layout,different functions,storage and drainage,regulation and control,adjustment between abundant and dry periods,mutually supplement among different sources,flows clearly,and excellent environment.
With the rapid development of economics and society,especially with the implementation of “reform and opening up” to the outside world,the industry and urbanization developed very quickly in China.The rapid development of industry resulted in the considerable need for water resources,and the great changes of water cycle among supply,uses,assumption and drainage.It further resulted in the great challenge on water supply,as well as the exacerbation of water quality and deterioration of aquatic ecosystems.On the other hand,rapid urbanization affected the relationship between rivers and lakes,and resulted in fragmentation of rivers and shrinkage even disappearance of lakes.In order to improve the water security,it is quite necessary to construct the national water networks with the capability of adjustment between abundant and dry periods,as well as complementary between western and eastern China.Considering the strategic needs of national water security,the overall layout of national water network was investigated,and the strategic needs of river-lake system connectivity were analyzed.Possible effects of river-lake system connectivity on water resources,flood control,ecological system,environment,society and economics were comprehensively analyzed through multidisciplinary ways.The function and roles of South-North Water Transfer Project in the construction of national water network were also identified.Great efforts have been made to comprehensively analyze the key issues and difficulties in river-lake system connectivity through multidisciplinary and systematic research,so as to provide reference and scientific support for the construction of national water network. From the analysis on the connectivity of river-lake system,it was found that the connection of river-lake system and the construction of national water networks are the most important national strategy to improve water security in China.Major functions and roles of the national water networks mainly focused on the improvement of water resources allocation and water supply,improvement of water quality and aquatic ecosystem,as well as the improvement of capability to mitigate floods and droughts.The objective of connection for rivers and lakes should respect the law of naturalized hydrological cycle and evolution of rivers and lakes,and consider the functions of water resources,environment,and ecology.Through the construction of reservoirs,dams/weirs,pumping stations and channels,national water networks will be constructed at the national,regional and urban scales.The water networks will be characterized with reasonable layout,different functions,storage and drainage,regulation and control,adjustment between abundant and dry periods,mutually supplement among different sources,flows clearly,and excellent environment.
2022, 20(4):765-772.
Abstract:
A pump is a device that can convert mechanical energy into liquid kinetic energy and achieve directional liquid transportation,and has been widely used in many fields.The tubular pump is widely used in low-lift pumping stations due to its high efficiency,good hydraulic performance,and compact structure.Compared with the axial flow pump and the mixed flow pump unit,under the same excavation conditions,the tubular pump unit can reduce the amount of plant excavation and the amount of concrete used,which greatly reduces the overall cost of the pumping station.Because the unit is horizontally arranged,the flow conditions are good,and the hydraulic loss is small.Compared with the vertical unit,the tubular pump plant has a simple structure and does not need to use a complex multi-layer structure,which reduces the overall cost.It is widely used in plain areas.In recent years,many scholars at home and abroad have conducted researches on the internal flow of tubular pumps.With the development of computer technology,the computational fluid dynamics (CFD) and computational solid mechanics (CSM) combined fluid-solid coupling calculation method has the advantages of short time-consuming,low cost,and easy access to flow data and solid data in the flow field.It is mostly used to calculate the interaction between fluid and solid inside fluid machinery. To obtain the stress,strain,and vibration characteristics of the fixed guide vane of the tubular pump,based on the unidirectional fluid-structure coupling method,the stress,strain,and wet modal analysis of the fixed guide vane of the rear bulb tubular pump under multi-flow conditions were carried out. The results show that with the increase in flow,the maximum equivalent stress and strain on the surface of the guide vane tend to decrease as a whole.The distribution of equivalent stress and strain on the surface of the guide vane is similar under low flow and design flow conditions.Under large flow conditions,the equivalent stress is distributed along the root of the guide vane of the water pump,accounting for 90% of the entire suction surface,and the larger strain appears in the middle and upper part of the outer edge of the guide vane,and the deformation area accounts for about 60% of the entire guide vane.The natural frequency of the guide vane has little relevance to the flow conditions,and its value increases with the increase of the order of the mode shape.The influence of flow factors can be ignored in the resonance risk analysis. (1) As the flow rate increases,the equivalent stress and strain on the surface of the guide vane tend to decrease.(2) The equivalent stress distribution area of the pressure surface of the guide vane under the design flow and the small flow condition is the same.It is located at the root and the middle of the outer edge of the inlet and outlet of the guide vane.Its size accounts for about 40% of the guide vane.The situation is quite different,from the inlet and outlet roots of the guide vane to the middle,and its size accounts for about 90% of the guide vane.It is recommended to pay attention to the equivalent stress at the root of the guide vane when designing the guide vane of the tubular pump.(3) Under different flow conditions,the strain distribution between the guide vanes is significantly different.The large strain area of each blade is mainly concentrated on the outer edge of the guide vane,and there is no obvious strain at the root of the guide vane.It is suggested that when designing the guide vane of the tubular pump,the strain change of the outer edge of the guide vane should be paid attention .(4) By analyzing the calculation results of the first ten wet modes of the guide vane,it is found that the vibration frequency of each order of the guide vane is not highly correlated with the flow factor.The value of the vibration frequency of the guide vane will increase with the increase of the order,but the increase is not large.Therefore,the resonance risk analysis can ignore the influence of flow changes on its vibration frequency.
A pump is a device that can convert mechanical energy into liquid kinetic energy and achieve directional liquid transportation,and has been widely used in many fields.The tubular pump is widely used in low-lift pumping stations due to its high efficiency,good hydraulic performance,and compact structure.Compared with the axial flow pump and the mixed flow pump unit,under the same excavation conditions,the tubular pump unit can reduce the amount of plant excavation and the amount of concrete used,which greatly reduces the overall cost of the pumping station.Because the unit is horizontally arranged,the flow conditions are good,and the hydraulic loss is small.Compared with the vertical unit,the tubular pump plant has a simple structure and does not need to use a complex multi-layer structure,which reduces the overall cost.It is widely used in plain areas.In recent years,many scholars at home and abroad have conducted researches on the internal flow of tubular pumps.With the development of computer technology,the computational fluid dynamics (CFD) and computational solid mechanics (CSM) combined fluid-solid coupling calculation method has the advantages of short time-consuming,low cost,and easy access to flow data and solid data in the flow field.It is mostly used to calculate the interaction between fluid and solid inside fluid machinery. To obtain the stress,strain,and vibration characteristics of the fixed guide vane of the tubular pump,based on the unidirectional fluid-structure coupling method,the stress,strain,and wet modal analysis of the fixed guide vane of the rear bulb tubular pump under multi-flow conditions were carried out. The results show that with the increase in flow,the maximum equivalent stress and strain on the surface of the guide vane tend to decrease as a whole.The distribution of equivalent stress and strain on the surface of the guide vane is similar under low flow and design flow conditions.Under large flow conditions,the equivalent stress is distributed along the root of the guide vane of the water pump,accounting for 90% of the entire suction surface,and the larger strain appears in the middle and upper part of the outer edge of the guide vane,and the deformation area accounts for about 60% of the entire guide vane.The natural frequency of the guide vane has little relevance to the flow conditions,and its value increases with the increase of the order of the mode shape.The influence of flow factors can be ignored in the resonance risk analysis. (1) As the flow rate increases,the equivalent stress and strain on the surface of the guide vane tend to decrease.(2) The equivalent stress distribution area of the pressure surface of the guide vane under the design flow and the small flow condition is the same.It is located at the root and the middle of the outer edge of the inlet and outlet of the guide vane.Its size accounts for about 40% of the guide vane.The situation is quite different,from the inlet and outlet roots of the guide vane to the middle,and its size accounts for about 90% of the guide vane.It is recommended to pay attention to the equivalent stress at the root of the guide vane when designing the guide vane of the tubular pump.(3) Under different flow conditions,the strain distribution between the guide vanes is significantly different.The large strain area of each blade is mainly concentrated on the outer edge of the guide vane,and there is no obvious strain at the root of the guide vane.It is suggested that when designing the guide vane of the tubular pump,the strain change of the outer edge of the guide vane should be paid attention .(4) By analyzing the calculation results of the first ten wet modes of the guide vane,it is found that the vibration frequency of each order of the guide vane is not highly correlated with the flow factor.The value of the vibration frequency of the guide vane will increase with the increase of the order,but the increase is not large.Therefore,the resonance risk analysis can ignore the influence of flow changes on its vibration frequency.
2022, 20(4):773-781.
Abstract:
The uneven distribution of water resources is a long-term and trend problem faced by many countries.The water transfer project is the main way to solve this problem.When long-distance water conveyance dispatching is carried out,hydraulic structures such as pumping stations are often set in the channels to remove the influence of topographic conditions on water conveyance restrictions.During operation,it is required to keep the water level balance among pumping stations as much as possible to avoid problems caused by sharp rises or falls in water levels.If the water level changes sharply with time,it may not only cause water abandonment among pumping stations,but also cause water supply damage or hydraulic oscillation of the whole system.Therefore,processing the water level information and establishing an appropriate water level prediction model of the pumping station,especially the water level prediction model in front of the pumping station,are of great significance to the management of the pumping station,water transfer,building safety and so on.However,up to now,it is still difficult to accurately predict the water level of the pumping station due to the interaction of various hydraulic structures. A lot of studies have reported the research progress of water level prediction based on physical mechanism and machine learning.The water level simulation based on physical mechanism mainly uses the hydrodynamic model with Saint Venant equation as the control equation to simulate one-dimensional channel flow.It requires complete information in the study area,but usually some data is missing.Therefore,this method has certain limitations.Machine learning methods include vector machine RVM model,grey system GM (1,1) model,multiple linear regression model,neural network model,etc.The advantages of vector machine RVM model,grey system GM(1,1) model and multiple linear regression model are suitable for complex prediction tasks,but the disadvantages are that the prediction accuracy of these methods need to be improved.In recent years,with the development of artificial intelligence,neural network has got plentiful results in water level prediction.NARX neural network is a nonlinear dynamic network structure.Based on linear regression model,it has the functions of input delay and feedback memories,and can better approximate and simulate complex multi input and multi output systems. In order to further improve the accuracy of water level prediction,a water level prediction model based on GRA-NARX neural network was proposed,which included grey relational analysis (GRA) and NARX neural network.At present,when using NARX neural network to predict time series,Levenberg Marquardt (LM) algorithms is the most commonly used training algorithm,while the other two algorithms are rarely evaluated.Taking Tundian pumping station of Miyun reservoir storage project as a research case,firstly,the water level information was cleaned by boxplot method,and then interpolated by mean filling method;secondly,the main factors were screened out by grey correlation analysis;thirdly,the water level prediction model of NARX neural network based on grey correlation analysis was constructed;finally,an analysis was performed in order to assess the impact on the water level prediction of different training algorithms and time delays,and compared with GRA-BP neural network. The results show that the Bayesian Regularization (BR) algorithm leads to prediction model with better forecasting accuracy of the highest correlation coefficient and the smallest mean square error among the three different training algorithms.In GRA-NARX-BR model,with the increase of time delay,the correlation coefficient is basically the same,the mean square error is smaller and smaller,and the training time is longer and longer.Compared with the prediction results of GRA-BP model,it is found that among the three training algorithms,GRA-NARX model can comprehensively consider the influencing factors in water level prediction,has better network prediction accuracy,and GRA-NARX-BR model has the highest prediction accuracy,which reflects the superiority of GRA-NARX model structure and strong network generalization ability,and can be used as an effective water level prediction method.
The uneven distribution of water resources is a long-term and trend problem faced by many countries.The water transfer project is the main way to solve this problem.When long-distance water conveyance dispatching is carried out,hydraulic structures such as pumping stations are often set in the channels to remove the influence of topographic conditions on water conveyance restrictions.During operation,it is required to keep the water level balance among pumping stations as much as possible to avoid problems caused by sharp rises or falls in water levels.If the water level changes sharply with time,it may not only cause water abandonment among pumping stations,but also cause water supply damage or hydraulic oscillation of the whole system.Therefore,processing the water level information and establishing an appropriate water level prediction model of the pumping station,especially the water level prediction model in front of the pumping station,are of great significance to the management of the pumping station,water transfer,building safety and so on.However,up to now,it is still difficult to accurately predict the water level of the pumping station due to the interaction of various hydraulic structures. A lot of studies have reported the research progress of water level prediction based on physical mechanism and machine learning.The water level simulation based on physical mechanism mainly uses the hydrodynamic model with Saint Venant equation as the control equation to simulate one-dimensional channel flow.It requires complete information in the study area,but usually some data is missing.Therefore,this method has certain limitations.Machine learning methods include vector machine RVM model,grey system GM (1,1) model,multiple linear regression model,neural network model,etc.The advantages of vector machine RVM model,grey system GM(1,1) model and multiple linear regression model are suitable for complex prediction tasks,but the disadvantages are that the prediction accuracy of these methods need to be improved.In recent years,with the development of artificial intelligence,neural network has got plentiful results in water level prediction.NARX neural network is a nonlinear dynamic network structure.Based on linear regression model,it has the functions of input delay and feedback memories,and can better approximate and simulate complex multi input and multi output systems. In order to further improve the accuracy of water level prediction,a water level prediction model based on GRA-NARX neural network was proposed,which included grey relational analysis (GRA) and NARX neural network.At present,when using NARX neural network to predict time series,Levenberg Marquardt (LM) algorithms is the most commonly used training algorithm,while the other two algorithms are rarely evaluated.Taking Tundian pumping station of Miyun reservoir storage project as a research case,firstly,the water level information was cleaned by boxplot method,and then interpolated by mean filling method;secondly,the main factors were screened out by grey correlation analysis;thirdly,the water level prediction model of NARX neural network based on grey correlation analysis was constructed;finally,an analysis was performed in order to assess the impact on the water level prediction of different training algorithms and time delays,and compared with GRA-BP neural network. The results show that the Bayesian Regularization (BR) algorithm leads to prediction model with better forecasting accuracy of the highest correlation coefficient and the smallest mean square error among the three different training algorithms.In GRA-NARX-BR model,with the increase of time delay,the correlation coefficient is basically the same,the mean square error is smaller and smaller,and the training time is longer and longer.Compared with the prediction results of GRA-BP model,it is found that among the three training algorithms,GRA-NARX model can comprehensively consider the influencing factors in water level prediction,has better network prediction accuracy,and GRA-NARX-BR model has the highest prediction accuracy,which reflects the superiority of GRA-NARX model structure and strong network generalization ability,and can be used as an effective water level prediction method.
DAI Changlei
,
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YU Miao
,
,
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SONG Chengjie
,
,
NADEZHDA Pavlova
,
WEI Yiru
,
,
LI Mengling
,
2022, 20(4):782-801.
Abstract:
Frozen soil hydrogeology mainly studies the spatial and temporal distribution and movement of water elements in frozen soil areas and their interaction with frozen soil.Microscopically,the unique hydrothermal parameters of frozen soil,such as freezing temperature,unfrozen water content and pore water pressure,determine the structure and physical and mechanical properties of frozen soil,and affect the freezing and thawing process of frozen soil.Macroscopically,the existence of permafrost has changed the conventional surface runoff and water system model,and the process of groundwater recharge,runoff and discharge has changed fundamentally due to the seasonal freezing and thawing of permafrost,which forms a special hydrogeological environment in permafrost region.The research progress of frozen soil hydrogeology at home and abroad from microscopic and macroscopic perspectives systematically summarized,and the technical methods including geophysical technology,hydrochemistry and frozen soil hydrological model are analyzes.The research results of groundwater overflow ice,snowmelt infiltration and frozen soil moisture conservation in alpine region are analyzed.The development trend of permafrost hydrology should further explore the mechanism of runoff generation and confluence on the basis of accumulating research data and technical methods,and establish a more perfect hydrological physical model of permafrost to quantitatively analyze the interaction between permafrost and water resources.
Frozen soil hydrogeology mainly studies the spatial and temporal distribution and movement of water elements in frozen soil areas and their interaction with frozen soil.Microscopically,the unique hydrothermal parameters of frozen soil,such as freezing temperature,unfrozen water content and pore water pressure,determine the structure and physical and mechanical properties of frozen soil,and affect the freezing and thawing process of frozen soil.Macroscopically,the existence of permafrost has changed the conventional surface runoff and water system model,and the process of groundwater recharge,runoff and discharge has changed fundamentally due to the seasonal freezing and thawing of permafrost,which forms a special hydrogeological environment in permafrost region.The research progress of frozen soil hydrogeology at home and abroad from microscopic and macroscopic perspectives systematically summarized,and the technical methods including geophysical technology,hydrochemistry and frozen soil hydrological model are analyzes.The research results of groundwater overflow ice,snowmelt infiltration and frozen soil moisture conservation in alpine region are analyzed.The development trend of permafrost hydrology should further explore the mechanism of runoff generation and confluence on the basis of accumulating research data and technical methods,and establish a more perfect hydrological physical model of permafrost to quantitatively analyze the interaction between permafrost and water resources.
2022, 20(4):802-813.
Abstract:
The traditional method of calculating an aquifer′s hydraulic characteristic parameters can not deduce the real-time continuous change of the hydraulic characteristic,which makes it difficult to analyze the change of aquifer permeability under external load.The response model of the aquifer′s head to the periodic high-frequency natural force provides a new idea for research.In recent years,it has been shown that the external stress loads may cause changes of the aquifer′s hydraulic characteristic parameters and the corresponding changes in groundwater flow movement.At present,the research mainly focuses on qualitative inference and explanation,and there were relatively few conclusions from quantitative calculation. Based on the systematic analysis and summary of the theoretical relationship between the tidal response of the well water level and the aquifer′s hydraulic characteristics,taking wells Dazu and Beibei in Huayingshan fault zone as examples,the specific storativity of the observation aquifer was deduced by the amplitude of tidal response,and the movement state of groundwater flow near the well hole was analyzed based by the phase shift of tidal analysis.Using the radial flow model and leaky aquifer system model,the permeability and the coefficient of leaky in the aquifer near the well bore were calculated.Taking the Wenchuan earthquake as an example,the changes in well water level and the aquifer′s hydraulic parameters during the earthquake were analyzed,the influence of seismic stress on the hydraulic characteristics and groundwater flow movement was discussed,and its change mechanism was proposed. The phase shift of the water level in well Dazu response to the M2 wave was negative,indicating that the groundwater movement in the aquifer near well Dazu is dominated by the radial flow.It was assumed that the specific storativity in the observation section of well Dazu is 1.55×10-6 m-1,and the horizontal permeability is 0.041 9 m/d,which was consistent with the results of the previous pumping test (0.053 4 m/d),indicating that it is feasible to calculate the hydraulic parameters of the aquifer by the tidal response of the well water level.Moreover,the locally developed fractures in the aquifer near well Beibei resulted in the coexistence of vertical and horizontal flows near the well.The specific storativity of the aquifer was estimated to be 1.41×10-6 m-1and the coefficient of leakage ranged from 1.5×10-8 to 2.5×10-8s-1.After the Wenchuan earthquake,the water levels of wells Beibei and Dazu changed step by step,and the vertical flow of groundwater in the aquifer increased. Combined with the regional hydrogeological conditions,it was proposed that the reasons for the water level changes in wells Beibei and Dazu caused by the Wenchuan earthquake were as follows:The Jurassic sandstone aquifer in this region has a unified hydraulic connection over a large range,and local fractures with large dip angle are developed.The occurrence of earthquake led to expansion deformation and fracture dredging of aquifers,under the action of gravity,groundwater flowed along the fracture channel,resulting in the decline of water level in wells Beibei and Dazu,and the enhancement of vertical water exchange near the well bores in the runoff area.The research results are helpful to improve the understanding of the interaction between aquifer stress and deformation and seepage,and further deepen the research on the response mechanism of borehole aquifer systems to seismicity.
The traditional method of calculating an aquifer′s hydraulic characteristic parameters can not deduce the real-time continuous change of the hydraulic characteristic,which makes it difficult to analyze the change of aquifer permeability under external load.The response model of the aquifer′s head to the periodic high-frequency natural force provides a new idea for research.In recent years,it has been shown that the external stress loads may cause changes of the aquifer′s hydraulic characteristic parameters and the corresponding changes in groundwater flow movement.At present,the research mainly focuses on qualitative inference and explanation,and there were relatively few conclusions from quantitative calculation. Based on the systematic analysis and summary of the theoretical relationship between the tidal response of the well water level and the aquifer′s hydraulic characteristics,taking wells Dazu and Beibei in Huayingshan fault zone as examples,the specific storativity of the observation aquifer was deduced by the amplitude of tidal response,and the movement state of groundwater flow near the well hole was analyzed based by the phase shift of tidal analysis.Using the radial flow model and leaky aquifer system model,the permeability and the coefficient of leaky in the aquifer near the well bore were calculated.Taking the Wenchuan earthquake as an example,the changes in well water level and the aquifer′s hydraulic parameters during the earthquake were analyzed,the influence of seismic stress on the hydraulic characteristics and groundwater flow movement was discussed,and its change mechanism was proposed. The phase shift of the water level in well Dazu response to the M2 wave was negative,indicating that the groundwater movement in the aquifer near well Dazu is dominated by the radial flow.It was assumed that the specific storativity in the observation section of well Dazu is 1.55×10-6 m-1,and the horizontal permeability is 0.041 9 m/d,which was consistent with the results of the previous pumping test (0.053 4 m/d),indicating that it is feasible to calculate the hydraulic parameters of the aquifer by the tidal response of the well water level.Moreover,the locally developed fractures in the aquifer near well Beibei resulted in the coexistence of vertical and horizontal flows near the well.The specific storativity of the aquifer was estimated to be 1.41×10-6 m-1and the coefficient of leakage ranged from 1.5×10-8 to 2.5×10-8s-1.After the Wenchuan earthquake,the water levels of wells Beibei and Dazu changed step by step,and the vertical flow of groundwater in the aquifer increased. Combined with the regional hydrogeological conditions,it was proposed that the reasons for the water level changes in wells Beibei and Dazu caused by the Wenchuan earthquake were as follows:The Jurassic sandstone aquifer in this region has a unified hydraulic connection over a large range,and local fractures with large dip angle are developed.The occurrence of earthquake led to expansion deformation and fracture dredging of aquifers,under the action of gravity,groundwater flowed along the fracture channel,resulting in the decline of water level in wells Beibei and Dazu,and the enhancement of vertical water exchange near the well bores in the runoff area.The research results are helpful to improve the understanding of the interaction between aquifer stress and deformation and seepage,and further deepen the research on the response mechanism of borehole aquifer systems to seismicity.
2022, 20(4):814-824.
Abstract:
The spatio-temporal characteristic of evapotranspiration can not only quantify the water loss caused by evaporation,but also reflect the relationship between land use,water resource allocation and utilization.It was also an indispensable basic data for calculating the balance of agricultural water and soil resources,and planning,design and management of irrigation projects.With the increasing contradiction between water resources supply and demand and the refined requirements of modern irrigation and agricultural water management,it was necessary to illustrate evapotranspiration evolution rules on different spatial and temporal scales. To illuminate the changing laws of evapotranspiration in different growth stages of winter wheat,Yongnian District of Handan city was selected as the study area,and the validated regional SEBAL model through Penman-Monteith model was applied for simulating evapotranspiration.The mean square root of variance was 0.65 which shows that SEBAL model accuracy was higher,and the model can provide relatively accurate ET value for the study area.Based on this,SEBAL model was applied to simulate the evapotranspiration of wheat at different growth stages from October 2019 to June 2020,and the spatio-temporal evolution law of evapotranspiration in different growth periods of regional winter wheat was analyzed respectively. The maximum daily evapotranspiration during the whole growth stage of winter [JP2]wheat is from 0.97 mm/d to 13.66 mm/d,[JP]and the average one ranges from 0.52 mm/d to 8.06 mm/d;the evapotranspiration was low in the west and high in the east,which was consistent with the irrigation difference caused by terrain and hydrgeological characteristics in the study area. (1) The regional daily evapotranspiration rose with fluctuations during the whole growth stage of winter wheat;the evapotranspiration was relatively low from seedling stage to regreening stage,with the regional evapotranspiration ranging from 0.52 mm/d to 1.49 mm/d;from double ridge stage to booting stage,the evapotranspiration ranged from 3.18 mm/d to 4.47 mm/d;from jointing stage to mature period (the critical growth stage),regional evapotranspiration increased rapidly,ranging from 4.47 mm/d to 8.06 mm/d.Overall,the evapotranspiration was the largest in summer,followed by spring,and the evapotranspiration was the smallest in autumn and winter.(2) The evapotranspiration in Yongnian District had a certain degree of temporal and spatial differences.The peak of regional evapotranspiration was spatially shifted between the seedling stage and regreening stage.In terms of the different growing stages,regional evapotranspiration from flowering stage to mature period was higher than from double ridge stage to booting stage,and regional evapotranspiration from double ridge stage to booting stage was higher than from seedling stage to regreening stage.The evapotranspiration in the central and northern regions of Yongnian District was the largest,followed by the southeast region,and the evapotranspiration in the western region was lower.(3) In the selected whole growth period,the daily evapotranspiration of winter wheat had a significant power relation with the average value of LAI,and the R2 was as high as 0.88,which revealed the quantitative relationship that the evapotranspiration increases positively with the change of LAI in Yongnian District.When the root quantity was low,the fluctuation of evapotranspiration was also low;with the rapid growth of crops,the root quantity showed an increasing trend and the evapotranspiration also showed a curved increasing trend in fluctuations.
The spatio-temporal characteristic of evapotranspiration can not only quantify the water loss caused by evaporation,but also reflect the relationship between land use,water resource allocation and utilization.It was also an indispensable basic data for calculating the balance of agricultural water and soil resources,and planning,design and management of irrigation projects.With the increasing contradiction between water resources supply and demand and the refined requirements of modern irrigation and agricultural water management,it was necessary to illustrate evapotranspiration evolution rules on different spatial and temporal scales. To illuminate the changing laws of evapotranspiration in different growth stages of winter wheat,Yongnian District of Handan city was selected as the study area,and the validated regional SEBAL model through Penman-Monteith model was applied for simulating evapotranspiration.The mean square root of variance was 0.65 which shows that SEBAL model accuracy was higher,and the model can provide relatively accurate ET value for the study area.Based on this,SEBAL model was applied to simulate the evapotranspiration of wheat at different growth stages from October 2019 to June 2020,and the spatio-temporal evolution law of evapotranspiration in different growth periods of regional winter wheat was analyzed respectively. The maximum daily evapotranspiration during the whole growth stage of winter [JP2]wheat is from 0.97 mm/d to 13.66 mm/d,[JP]and the average one ranges from 0.52 mm/d to 8.06 mm/d;the evapotranspiration was low in the west and high in the east,which was consistent with the irrigation difference caused by terrain and hydrgeological characteristics in the study area. (1) The regional daily evapotranspiration rose with fluctuations during the whole growth stage of winter wheat;the evapotranspiration was relatively low from seedling stage to regreening stage,with the regional evapotranspiration ranging from 0.52 mm/d to 1.49 mm/d;from double ridge stage to booting stage,the evapotranspiration ranged from 3.18 mm/d to 4.47 mm/d;from jointing stage to mature period (the critical growth stage),regional evapotranspiration increased rapidly,ranging from 4.47 mm/d to 8.06 mm/d.Overall,the evapotranspiration was the largest in summer,followed by spring,and the evapotranspiration was the smallest in autumn and winter.(2) The evapotranspiration in Yongnian District had a certain degree of temporal and spatial differences.The peak of regional evapotranspiration was spatially shifted between the seedling stage and regreening stage.In terms of the different growing stages,regional evapotranspiration from flowering stage to mature period was higher than from double ridge stage to booting stage,and regional evapotranspiration from double ridge stage to booting stage was higher than from seedling stage to regreening stage.The evapotranspiration in the central and northern regions of Yongnian District was the largest,followed by the southeast region,and the evapotranspiration in the western region was lower.(3) In the selected whole growth period,the daily evapotranspiration of winter wheat had a significant power relation with the average value of LAI,and the R2 was as high as 0.88,which revealed the quantitative relationship that the evapotranspiration increases positively with the change of LAI in Yongnian District.When the root quantity was low,the fluctuation of evapotranspiration was also low;with the rapid growth of crops,the root quantity showed an increasing trend and the evapotranspiration also showed a curved increasing trend in fluctuations.
2022, 20(4):825-832.
Abstract:
Large-scale mining of river sand and gravel in Hebei Province had been going on for many years.At present,the total amount of controlled mining of some river channels with sand mining planning in Hebei Province had been nearly exhausted.However,with the accelerated pace of urban construction and infrastructure construction in Hebei Province,the demand for sand and stone continued to grow in the near and long term.Under the driving of high interests,various illegal sand mining activities were increasingly intensified,and the contradiction between supply and demand of sand and stone is increasingly prominent.Reasonably protecting,exploring,utilizing of river sand resources and promoting the institutionalization and standardization of river sand mining management were important links to realize the ecological environment protection and ecological restoration of rivers and lakes in Hebei Province. The data of sand excavation plan in Hebei Province were collated and analyzed,and by which,the current situation of rivers in each water system,the range and characteristics of sand extraction in Hebei were definited.The sand mining planning data approved by Hebei Province and various cities from 2012 to 2018 were used for statistics,the satellite remote sensing image was used for analyzing,and the field survey results were used for correction.By which,the remaining reserves of controlled mining amount of river (river section) with sand mining planning in different prefectures and cities in the province were estimated.Taking the mass ratio of cement to sand and gravel 1∶1.49 as the ratio,and using the statistical data of bulk cement consumption in various cities and prefectures of Hebei Province from 2014 to 2017,the supply of sand and gravel in Beijing and Tianjin and other uses of sand and gravel in Hebei Province were comprehensively considered to be corrected,the sand and gravel consumption and annual average demand in Hebei Province were estimated.According to the estimation results,the supply and demand relationship of river sand in Hebei Province was quantitatively analyzed. The results were as follows:The planned sand mining channels in Hebei Province were mainly distributed in mountainous areas and piedmont plain,the number of planned channels for sand mining in alluvial plain area was relatively small,and the areas with better sand quality are mostly located in the piedmont plain.The main mining method was dry-mining.The actual remaining reserves of controlled sand mining in Hebei Province is about 389 million cubic meters after deducting the remaining reserves in difficult-to exploit areas and a small amount of remaining reserves in Langfang City.There were significant differences in the distribution of sand and gravel residual reserves in different cities:Shijiazhuang,Baoding,Xingtai sand reserves are less;The amount of sand and gravel mining in Handan river was relatively small;In Tangshan,Qinhuangdao,Zhangjiakou river channel,the proportion of controlled sand and gravel mining surplus was large,while in Langfang,Cangzhou and Hengshui area,the remaining sand and gravel reserves were very small and difficult to use.In the future,the sand and gravel mining in Hebei Province will be mainly based on the planned residual reserves.The average annual sand and gravel demand in Hebei Province was estimated to be 117 million cubic meters.The average annual demand for sand in Shijiazhuang,Baoding,Xingtai and Handan was large,the available supply of sand and gravel was increasingly severe,and with the construction of Xiongan New Area,the supply gap of sand and gravel was huge in the future;The remaining reserves in Tangshan,Chengde and Zhangjiakou could meet the sand and gravel supply for more than 5 years;Cangzhou,Hengshui,Langfang and Qinhuangdao were relatively short of sand and stone resources,and they mainly used external sand and stone resources,which will produce sand and stone supply pressure on surrounding cities. On the contradiction analysis of the imbalance between supply and demand,the reasons were mainly concentrated in three points:after years of continuous sand mining,the river resources that could supply high-quality sand and gravel in Hebei Province were nearly exhausted,especially in the piedmont plain area;most of the river channels in the province had not compiled the channel sand mining and regulation planning and annual implementation plan,resulting in the channel sand could not be mined at present;some counties and cities had banned the mining of rivers under their jurisdiction,which lead to the ineffective use of sand and stone resources within their jurisdiction,and these cities need to purchase sand and stone. Given the contradiction between supply and demand,three advice was put forward,just as following:Accelerate the implementation of river regulation plan,strictly implement the river chief system and lake chief system,and ensure the implementation of the plan;Establish and perfect channel sand mining management system,accelerate the implementation of sand mining -unified management mode,through the unified management of sand mining,strengthen the supply of sand and reduce the external purchase of sand and gravel;replace river sand with machine-made sand and reduce demand for river sand by broadening supply sources.Some references were provided for controlling the irrational flow of river sand in Hebei Province and regulating the operation and management of sand mining.
Large-scale mining of river sand and gravel in Hebei Province had been going on for many years.At present,the total amount of controlled mining of some river channels with sand mining planning in Hebei Province had been nearly exhausted.However,with the accelerated pace of urban construction and infrastructure construction in Hebei Province,the demand for sand and stone continued to grow in the near and long term.Under the driving of high interests,various illegal sand mining activities were increasingly intensified,and the contradiction between supply and demand of sand and stone is increasingly prominent.Reasonably protecting,exploring,utilizing of river sand resources and promoting the institutionalization and standardization of river sand mining management were important links to realize the ecological environment protection and ecological restoration of rivers and lakes in Hebei Province. The data of sand excavation plan in Hebei Province were collated and analyzed,and by which,the current situation of rivers in each water system,the range and characteristics of sand extraction in Hebei were definited.The sand mining planning data approved by Hebei Province and various cities from 2012 to 2018 were used for statistics,the satellite remote sensing image was used for analyzing,and the field survey results were used for correction.By which,the remaining reserves of controlled mining amount of river (river section) with sand mining planning in different prefectures and cities in the province were estimated.Taking the mass ratio of cement to sand and gravel 1∶1.49 as the ratio,and using the statistical data of bulk cement consumption in various cities and prefectures of Hebei Province from 2014 to 2017,the supply of sand and gravel in Beijing and Tianjin and other uses of sand and gravel in Hebei Province were comprehensively considered to be corrected,the sand and gravel consumption and annual average demand in Hebei Province were estimated.According to the estimation results,the supply and demand relationship of river sand in Hebei Province was quantitatively analyzed. The results were as follows:The planned sand mining channels in Hebei Province were mainly distributed in mountainous areas and piedmont plain,the number of planned channels for sand mining in alluvial plain area was relatively small,and the areas with better sand quality are mostly located in the piedmont plain.The main mining method was dry-mining.The actual remaining reserves of controlled sand mining in Hebei Province is about 389 million cubic meters after deducting the remaining reserves in difficult-to exploit areas and a small amount of remaining reserves in Langfang City.There were significant differences in the distribution of sand and gravel residual reserves in different cities:Shijiazhuang,Baoding,Xingtai sand reserves are less;The amount of sand and gravel mining in Handan river was relatively small;In Tangshan,Qinhuangdao,Zhangjiakou river channel,the proportion of controlled sand and gravel mining surplus was large,while in Langfang,Cangzhou and Hengshui area,the remaining sand and gravel reserves were very small and difficult to use.In the future,the sand and gravel mining in Hebei Province will be mainly based on the planned residual reserves.The average annual sand and gravel demand in Hebei Province was estimated to be 117 million cubic meters.The average annual demand for sand in Shijiazhuang,Baoding,Xingtai and Handan was large,the available supply of sand and gravel was increasingly severe,and with the construction of Xiongan New Area,the supply gap of sand and gravel was huge in the future;The remaining reserves in Tangshan,Chengde and Zhangjiakou could meet the sand and gravel supply for more than 5 years;Cangzhou,Hengshui,Langfang and Qinhuangdao were relatively short of sand and stone resources,and they mainly used external sand and stone resources,which will produce sand and stone supply pressure on surrounding cities. On the contradiction analysis of the imbalance between supply and demand,the reasons were mainly concentrated in three points:after years of continuous sand mining,the river resources that could supply high-quality sand and gravel in Hebei Province were nearly exhausted,especially in the piedmont plain area;most of the river channels in the province had not compiled the channel sand mining and regulation planning and annual implementation plan,resulting in the channel sand could not be mined at present;some counties and cities had banned the mining of rivers under their jurisdiction,which lead to the ineffective use of sand and stone resources within their jurisdiction,and these cities need to purchase sand and stone. Given the contradiction between supply and demand,three advice was put forward,just as following:Accelerate the implementation of river regulation plan,strictly implement the river chief system and lake chief system,and ensure the implementation of the plan;Establish and perfect channel sand mining management system,accelerate the implementation of sand mining -unified management mode,through the unified management of sand mining,strengthen the supply of sand and reduce the external purchase of sand and gravel;replace river sand with machine-made sand and reduce demand for river sand by broadening supply sources.Some references were provided for controlling the irrational flow of river sand in Hebei Province and regulating the operation and management of sand mining.
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