Volume 19,Issue 6,2021 Table of Contents
2021, 19(6):1041-1071.
Abstract:
Water conservation is closely related to ecosystem processes,production and life of human beings.In-depth research of water conservation is of guiding significance for promoting harmonious coexistence between humans and water and is vital to the health of ecosystems and the sustainable development of human society.With the deepening of the research and application of water conservation,its connotation is gradually enriched,and the evaluation methods become more diverse.However,the definition of water conservation in previous studies is vague,and the comprehensive comparative analysis of various evaluation methods is lacking.Therefore,it is urgent to define the connotation of water conservation and analyze the applicability of its various estimation methods.The history of water conservation research is reviewed by literature analysis,which can be divided into four stages:cognition and germination stage,theory development stage,quantitative calculation stage,and comprehensive model evaluation stage.On this basis,the connotation of water conservation is clearly defined from three aspects of definition,water quantity,and function.The existing estimation methods of water conservation are collected and sorted out,and systematic comparative analysis is carried out on the principles,time and space scales,the application scope,and advantages & disadvantages.The possible research direction on water conservation in the future was also put forward.
Water conservation is closely related to ecosystem processes,production and life of human beings.In-depth research of water conservation is of guiding significance for promoting harmonious coexistence between humans and water and is vital to the health of ecosystems and the sustainable development of human society.With the deepening of the research and application of water conservation,its connotation is gradually enriched,and the evaluation methods become more diverse.However,the definition of water conservation in previous studies is vague,and the comprehensive comparative analysis of various evaluation methods is lacking.Therefore,it is urgent to define the connotation of water conservation and analyze the applicability of its various estimation methods.The history of water conservation research is reviewed by literature analysis,which can be divided into four stages:cognition and germination stage,theory development stage,quantitative calculation stage,and comprehensive model evaluation stage.On this basis,the connotation of water conservation is clearly defined from three aspects of definition,water quantity,and function.The existing estimation methods of water conservation are collected and sorted out,and systematic comparative analysis is carried out on the principles,time and space scales,the application scope,and advantages & disadvantages.The possible research direction on water conservation in the future was also put forward.
2021, 19(6):1072-1082.
Abstract:
In arid and semi-arid regions,water scarcity poses prominent constraints to socio-economic development and threatens nature ecosystem conservation.Hydrological models represent integrated and systematic knowledge of catchment hydrology,which is essential to forecast floods and droughts,and decisions-makings on water resources management.However,the model performance in arid and semi-arid regions is far from satisfactory and the runoff generation mechanism is much more complex due to heterogeneous landscapes and complex hydrometeorological processes in humid regions.The topographic-driven HSC (HAND-based storage capacity curve) runoff generation model using the topographic information to derive the non-linear relationship between the relative soil moisture and the extent of saturated areas in catchment scale.Compared with HBV and TOPMODEL,HSC model performed better in hundreds of catchments in the United States,especially in the semi-arid catchment with gentle slopes,less forest coverage.However,the model performance in China′s arid and semiarid hilly catchments is still unknown. The HSC topography-driven runoff generation model uses the topographic index HAND (height above the nearest drainage) to establish the HAND-based storage capacity curve,which allows to estimate the spatial distribution of storage capacity without parameter calibration.Besides,through the mass curve technique (MCT) method,the parameter of root zone storage capacity (Sumax) can be derived from climate data.Coupling HSC with MCT,the HSC-MCT runoff generation model is established which does not require parameter calibration.To test HSC′s performance,three benchmark models:the HBV′s beta function,the Xin′anjiang model′s water storage capacity curve,and the infiltration excess model which is based on rainfall threshold were used for comparison.The Yebaishou watershed,a typical semiarid hilly region in Liaoning Province of China,was used as a study site.The Kling-Gupta efficiency (IKGE),the root mean square error (ERMS),and the coefficient of determination (R2) was used to evaluate model performance.The hydrological and meteorological data of the Yebaishou watershed from 1961 to 1970 was used to calibrate the extra free parameters,including routing module and three benchmark runoff generation modules,by the MOSCEMUA (multi-objective parameter optimization algorithm),and period from 1971 to 1980 was used for validation. Five models could reproduce the timing of the main peak flows very well.The HSC-MCT performed well in both calibration and validation for simulating the volume of peak flow,but the other four models overestimated peak flows.However,for the maximum peak flood simulation in 1962,the HSC-MCT and the infiltration excess model underestimated the peak flood,but the HSC,HBV,and Xin′anjiang could reproduce this event well.In terms of evaluation metrics,such as IKGE,ERMS,and R2,it was found that despite the other four models were of good results during calibration,the simulation results in validation significantly deteriorated.The calibrated parameters of these models were far beyond their range of physical reality,for example,the parameter of maximum interception capacity (Simax),and the parameter of root zone storage capacity (Sumax).The HSC-MCT model had the best performance in validation,and maintain robustness thoroughly. The extreme peak flow had a strong influence on model performance and parameter calibration.But the HSC-MCT model allows us to derive the root zone storage capacity (Sumax) by climate data and its spatial pattern by topography information,thus free of parameter calibration,and avoid parameter overfitting.In summary,the robustness and stability of HSC-MCT model to simulate hydrological processes is satisfactory in this semi-arid Yebaishou watershed.
In arid and semi-arid regions,water scarcity poses prominent constraints to socio-economic development and threatens nature ecosystem conservation.Hydrological models represent integrated and systematic knowledge of catchment hydrology,which is essential to forecast floods and droughts,and decisions-makings on water resources management.However,the model performance in arid and semi-arid regions is far from satisfactory and the runoff generation mechanism is much more complex due to heterogeneous landscapes and complex hydrometeorological processes in humid regions.The topographic-driven HSC (HAND-based storage capacity curve) runoff generation model using the topographic information to derive the non-linear relationship between the relative soil moisture and the extent of saturated areas in catchment scale.Compared with HBV and TOPMODEL,HSC model performed better in hundreds of catchments in the United States,especially in the semi-arid catchment with gentle slopes,less forest coverage.However,the model performance in China′s arid and semiarid hilly catchments is still unknown. The HSC topography-driven runoff generation model uses the topographic index HAND (height above the nearest drainage) to establish the HAND-based storage capacity curve,which allows to estimate the spatial distribution of storage capacity without parameter calibration.Besides,through the mass curve technique (MCT) method,the parameter of root zone storage capacity (Sumax) can be derived from climate data.Coupling HSC with MCT,the HSC-MCT runoff generation model is established which does not require parameter calibration.To test HSC′s performance,three benchmark models:the HBV′s beta function,the Xin′anjiang model′s water storage capacity curve,and the infiltration excess model which is based on rainfall threshold were used for comparison.The Yebaishou watershed,a typical semiarid hilly region in Liaoning Province of China,was used as a study site.The Kling-Gupta efficiency (IKGE),the root mean square error (ERMS),and the coefficient of determination (R2) was used to evaluate model performance.The hydrological and meteorological data of the Yebaishou watershed from 1961 to 1970 was used to calibrate the extra free parameters,including routing module and three benchmark runoff generation modules,by the MOSCEMUA (multi-objective parameter optimization algorithm),and period from 1971 to 1980 was used for validation. Five models could reproduce the timing of the main peak flows very well.The HSC-MCT performed well in both calibration and validation for simulating the volume of peak flow,but the other four models overestimated peak flows.However,for the maximum peak flood simulation in 1962,the HSC-MCT and the infiltration excess model underestimated the peak flood,but the HSC,HBV,and Xin′anjiang could reproduce this event well.In terms of evaluation metrics,such as IKGE,ERMS,and R2,it was found that despite the other four models were of good results during calibration,the simulation results in validation significantly deteriorated.The calibrated parameters of these models were far beyond their range of physical reality,for example,the parameter of maximum interception capacity (Simax),and the parameter of root zone storage capacity (Sumax).The HSC-MCT model had the best performance in validation,and maintain robustness thoroughly. The extreme peak flow had a strong influence on model performance and parameter calibration.But the HSC-MCT model allows us to derive the root zone storage capacity (Sumax) by climate data and its spatial pattern by topography information,thus free of parameter calibration,and avoid parameter overfitting.In summary,the robustness and stability of HSC-MCT model to simulate hydrological processes is satisfactory in this semi-arid Yebaishou watershed.
2021, 19(6):1083-1092.
Abstract:
The process of urbanization continue to intensify due to China′s rapid economic and social development,resulting in a series of urban water problems,such as the shortage of water resources,urban rainstorm waterlogging,water environmental pollution and water ecological damage.Urban waterlogging problem caused by short-term rainstorms is particularly significant,which causes great losses and has a wide range of impact,and has become the focus of social and scientific circles. Based on the advantages of the SWMM model and LISFLOOD-FP model,coupling one-dimensional pipe network and two-dimensional inundation model,calibration and verification was carried out using historical rainfall,flood flow extract data,and inundation data to analyze the distribution characteristics of overflow nodes,inundation depth and range under different rainstorm scenarios to provide some scientific and technological support for flood control and disaster reduction in Jinan City. Validation of coupling model showed good applicability in the study area;With the increase of precipitation return period,the number of flooding nodes and water depth range of inundation showed an increasing trend.The total inundation area increased from 8.18 km2 to 21.92 km2,and the inundation area with a water depth range of 0.1-1.0 m showed the largest proportion.The results can provide scientific and technological support for flood control and disaster reduction in the study area. The simulation results of the SWMM and LISFLOOD-FP coupling model show the location of waterlogging prone points in the strudy area.The submergence depth of most grids at the intersection of 2nd Ring West Road and Zhangzhuang Road is between 0.1 m and 1.0 m,and the maximum water depth monitored is 0.34 m,which indicates that the coupling model has good applicability.The model can be used to carry out relevant research work.With the increase of design precipitation return period,the overflow node and inundation range show a significant increasing trend.When the design precipitation return period increases from 1 year to 5 years,the overflow nodes increase the most,and the main streets are flooded to varying degrees.The 5-year return period design precipitation has caused serious waterlogging,which indicates that the drainage capacity of the study area lags.LISFLOOD-FP two-dimensional simulation results show that there is water accumulation in some low-lying areas such as rivers and lakes in the study area,which is different from the actual situation.The reason may be related to the accuracy of input DEM data.In this case,further fine processing of DEM data can better describe the actual surface flooding process.
The process of urbanization continue to intensify due to China′s rapid economic and social development,resulting in a series of urban water problems,such as the shortage of water resources,urban rainstorm waterlogging,water environmental pollution and water ecological damage.Urban waterlogging problem caused by short-term rainstorms is particularly significant,which causes great losses and has a wide range of impact,and has become the focus of social and scientific circles. Based on the advantages of the SWMM model and LISFLOOD-FP model,coupling one-dimensional pipe network and two-dimensional inundation model,calibration and verification was carried out using historical rainfall,flood flow extract data,and inundation data to analyze the distribution characteristics of overflow nodes,inundation depth and range under different rainstorm scenarios to provide some scientific and technological support for flood control and disaster reduction in Jinan City. Validation of coupling model showed good applicability in the study area;With the increase of precipitation return period,the number of flooding nodes and water depth range of inundation showed an increasing trend.The total inundation area increased from 8.18 km2 to 21.92 km2,and the inundation area with a water depth range of 0.1-1.0 m showed the largest proportion.The results can provide scientific and technological support for flood control and disaster reduction in the study area. The simulation results of the SWMM and LISFLOOD-FP coupling model show the location of waterlogging prone points in the strudy area.The submergence depth of most grids at the intersection of 2nd Ring West Road and Zhangzhuang Road is between 0.1 m and 1.0 m,and the maximum water depth monitored is 0.34 m,which indicates that the coupling model has good applicability.The model can be used to carry out relevant research work.With the increase of design precipitation return period,the overflow node and inundation range show a significant increasing trend.When the design precipitation return period increases from 1 year to 5 years,the overflow nodes increase the most,and the main streets are flooded to varying degrees.The 5-year return period design precipitation has caused serious waterlogging,which indicates that the drainage capacity of the study area lags.LISFLOOD-FP two-dimensional simulation results show that there is water accumulation in some low-lying areas such as rivers and lakes in the study area,which is different from the actual situation.The reason may be related to the accuracy of input DEM data.In this case,further fine processing of DEM data can better describe the actual surface flooding process.
2021, 19(6):1093-1103.
Abstract:
The Shihuiyao basin is located in the upper of the Nenjiang River,with basin area of 17,205 km2.Fewer rainfall stations within or near the basin lead to insufficient rainfall data.It is difficult to accurately predict the flooding process at the outlet section of the basin using existing rainfall data,which brings certain difficulties to the downstream river flood control and the Nierji Reservoir′s forecast flood control operations.Based on the characteristic of flood forecasting,the near real-time satellite remote sensing global precipitation products GSMaP_NRT and GSMaP_Gauge_NRT are selected to supplement the Shihuiyao basin,aiming to solve the problem of scarcely gauged precipitation. The two products accuracy on the rainfall stations grid is evaluated based on the precipitation within or near the basin.Three flood forecasting input schemes are designed:scheme I precipitation of rainfall stations within or near the basin by Tyson polygon weighted method),scheme Ⅱ(average precipitation of GSMaP_NRT in the basin),scheme Ⅲ (average precipitation of GSMaP_Gauge_NRT in the basin),and combined with the Xin′anjiang model for flood forecasting to verify their availability. On monthly and daily scales for flood season,GSMaP_NRT and GSMaP_Gauge_NRT show high accuracy,but both overestimate the rain gauge observation precipitation,and the accuracy of GSMaP_Gauge_NRT is generally better than that of GSMaP_NRT.The results of 8 flood forecasts during the training and validation stages show that the forecast effect of scheme Ⅲ is the best,and the runoff and confluence results both have higher accuracies. Results indicated that the GSMaP_Gauge_NRT has high availability in flood forecasting in the Shihuiyao basin,and the GSMaP_Gauge_NRT can be used as a source of rainfall data in ungauged basins.In future,more near real-time satellite remote sensing global precipitation products can be applied for flood forecasting to further improve flood forecasting accuracy.
The Shihuiyao basin is located in the upper of the Nenjiang River,with basin area of 17,205 km2.Fewer rainfall stations within or near the basin lead to insufficient rainfall data.It is difficult to accurately predict the flooding process at the outlet section of the basin using existing rainfall data,which brings certain difficulties to the downstream river flood control and the Nierji Reservoir′s forecast flood control operations.Based on the characteristic of flood forecasting,the near real-time satellite remote sensing global precipitation products GSMaP_NRT and GSMaP_Gauge_NRT are selected to supplement the Shihuiyao basin,aiming to solve the problem of scarcely gauged precipitation. The two products accuracy on the rainfall stations grid is evaluated based on the precipitation within or near the basin.Three flood forecasting input schemes are designed:scheme I precipitation of rainfall stations within or near the basin by Tyson polygon weighted method),scheme Ⅱ(average precipitation of GSMaP_NRT in the basin),scheme Ⅲ (average precipitation of GSMaP_Gauge_NRT in the basin),and combined with the Xin′anjiang model for flood forecasting to verify their availability. On monthly and daily scales for flood season,GSMaP_NRT and GSMaP_Gauge_NRT show high accuracy,but both overestimate the rain gauge observation precipitation,and the accuracy of GSMaP_Gauge_NRT is generally better than that of GSMaP_NRT.The results of 8 flood forecasts during the training and validation stages show that the forecast effect of scheme Ⅲ is the best,and the runoff and confluence results both have higher accuracies. Results indicated that the GSMaP_Gauge_NRT has high availability in flood forecasting in the Shihuiyao basin,and the GSMaP_Gauge_NRT can be used as a source of rainfall data in ungauged basins.In future,more near real-time satellite remote sensing global precipitation products can be applied for flood forecasting to further improve flood forecasting accuracy.
2021, 19(6):1104-1,113.
Abstract:
The North China Plain has become the most serious groundwater overexploitation area in China due to development and utilization of groundwater resources.Rainwater resources have gradually attracted people′s attention because of potential water resources.However,most of the current researches focuses on increasing the conversion rate of rain-flood resources and analyzing the fluctuation of groundwater level,lacking the concerns on the characteristics and amount of groundwater recharge under the influence of rain-storm flood events.Based on the systematic analysis of rain and flood events,the response characteristics of groundwater to rain-storm flood events is discussed,a groundwater recharge solution model based on ArcGIS software is proposed to quantitatively analyze the response of groundwater to the events. 7/19 heavy rain-storm flood event in Anyang City is taken as an example.Based on the long-term monitoring data of groundwater level and rainfall,the grey correlation coefficient between the elevation value of groundwater level and the precipitation in the corresponding period is calculated,and the correlation between the variation range of groundwater level and the precipitation is determined.The collected monitoring data of the 7/19 heavy rain from groundwater level monitoring wells and precipitation monitoring stations in the plain area of Anyang City are used to analyze the spatial distribution characteristics of rainfall.Groundwater recharge solution model is established through ArcGIS according to the temporal and spatial distribution characteristics of rainfall and the changing trend of groundwater level.The steps are as follows:the variation of groundwater level is calculated and the point data is filled into the whole study area by Kriging interpolation;use the surface analysis tools of ArcGIS to partition data such as water level variation and hydrogeological parameters to establish corresponding attribute thematic layers;perform overlay analysis on attribute thematic layers,define projection to calculate the recharge of groundwater. The correlation coefficient show that phreatic level and precipitation is greater than 0.85,which reflects the amount of groundwater resources is significantly affected by rainfall intensity.The 7/19 heavy rain formed two rainfall centers:One is located in the western part of Anyang County and the northeastern part of Linzhou,distributed in a north-south direction.Other one is located in the urban area of Anyang and central Anyang County,distributed in a southeast-northwest direction.The total process of flood discharge caused by heavy rain lasted 40 hours.The total amount of discharged floodwater reached 65.6 billion m3 based on estimation of the large cross-section measurement in Anyang Station.The model calculated total amount of groundwater recharged to the study area was 519 million m3,the flood conversion rate was 0.8%.Using the same model to analyze the storm flood events since 1980,the response degree of shallow groundwater to storm floods is directly proportional to the precipitation intensity. Compared with other studies,it is an efficient,intuitive,and feasible method to establish a solution model by using ArcGIS software to determine groundwater recharge which has relatively low data requirements.In addition to the 7/19 event,the analysis and calculation of three torrential rain and flood events in Anyang City exhibited good results.This model is suitable for the calculation of groundwater replenishment and quantitative analysis of rainwater resource utilization in areas with limited data.It also provides a certain reference value for rainwater resource utilization and groundwater response analysis.Under the influence of human activities,there are various correlations between the change of shallow groundwater level and precipitation in different regions.It is necessary to determine the correlation between the change of groundwater level and precipitation to exclude the influence of other factors on the change of groundwater level to ensure the accuracy of the model.
The North China Plain has become the most serious groundwater overexploitation area in China due to development and utilization of groundwater resources.Rainwater resources have gradually attracted people′s attention because of potential water resources.However,most of the current researches focuses on increasing the conversion rate of rain-flood resources and analyzing the fluctuation of groundwater level,lacking the concerns on the characteristics and amount of groundwater recharge under the influence of rain-storm flood events.Based on the systematic analysis of rain and flood events,the response characteristics of groundwater to rain-storm flood events is discussed,a groundwater recharge solution model based on ArcGIS software is proposed to quantitatively analyze the response of groundwater to the events. 7/19 heavy rain-storm flood event in Anyang City is taken as an example.Based on the long-term monitoring data of groundwater level and rainfall,the grey correlation coefficient between the elevation value of groundwater level and the precipitation in the corresponding period is calculated,and the correlation between the variation range of groundwater level and the precipitation is determined.The collected monitoring data of the 7/19 heavy rain from groundwater level monitoring wells and precipitation monitoring stations in the plain area of Anyang City are used to analyze the spatial distribution characteristics of rainfall.Groundwater recharge solution model is established through ArcGIS according to the temporal and spatial distribution characteristics of rainfall and the changing trend of groundwater level.The steps are as follows:the variation of groundwater level is calculated and the point data is filled into the whole study area by Kriging interpolation;use the surface analysis tools of ArcGIS to partition data such as water level variation and hydrogeological parameters to establish corresponding attribute thematic layers;perform overlay analysis on attribute thematic layers,define projection to calculate the recharge of groundwater. The correlation coefficient show that phreatic level and precipitation is greater than 0.85,which reflects the amount of groundwater resources is significantly affected by rainfall intensity.The 7/19 heavy rain formed two rainfall centers:One is located in the western part of Anyang County and the northeastern part of Linzhou,distributed in a north-south direction.Other one is located in the urban area of Anyang and central Anyang County,distributed in a southeast-northwest direction.The total process of flood discharge caused by heavy rain lasted 40 hours.The total amount of discharged floodwater reached 65.6 billion m3 based on estimation of the large cross-section measurement in Anyang Station.The model calculated total amount of groundwater recharged to the study area was 519 million m3,the flood conversion rate was 0.8%.Using the same model to analyze the storm flood events since 1980,the response degree of shallow groundwater to storm floods is directly proportional to the precipitation intensity. Compared with other studies,it is an efficient,intuitive,and feasible method to establish a solution model by using ArcGIS software to determine groundwater recharge which has relatively low data requirements.In addition to the 7/19 event,the analysis and calculation of three torrential rain and flood events in Anyang City exhibited good results.This model is suitable for the calculation of groundwater replenishment and quantitative analysis of rainwater resource utilization in areas with limited data.It also provides a certain reference value for rainwater resource utilization and groundwater response analysis.Under the influence of human activities,there are various correlations between the change of shallow groundwater level and precipitation in different regions.It is necessary to determine the correlation between the change of groundwater level and precipitation to exclude the influence of other factors on the change of groundwater level to ensure the accuracy of the model.
2021, 19(6):1114-1,124.
Abstract:
In recent decades,global climate change,especially anthropogenic activities such as land use change and reservoir construction have led to profound changes in hydrological processes in basins.Therefore,runoff change and attribution analysis under changing environment have become a hot research area among domestic and overseas scholars .The elastic coefficient method based on Budyko hypothesis is an effective method for the attribution analysis of runoff change,but its calculation results have some errors.Therefore,the Hanjiang River basin,which is sensitive to climate change and where human activities are intense is selected as the research object.The contribution rate of climate change and underlying surface change to runoff variability was quantitatively decomposed by the complementary relationship method of Budyko hypothesis,to provide a scientific basis for water resources management and sustainable utilization. The linear trend estimation and the moving average method were used to analyze the change trends of hydrometeorological elements at Baihe and Shayang stations in the Hanjiang River basin based on the hydrometeorological data such as temperature,precipitation and runoff from 1964 to 2015.Mann-Kendall test and Pettitt test were used to detect the abrupt change points in the annual runoff series at two stations.Based on Budyko′shydro-thermal coupling equilibrium theory,the elastic coefficients of runoff were calculated,and the complementary relationship method was used to quantitatively distinguish the contribution rate of each influencing factor to runoff change.Finally,the influence of climate and vegetation cover change on runoff change was discussed. From 1964 to 2015,the runoff of Baihe and Shayang stations showed a decreasing trend,with the change rate of -2.797 mm/a and -1.875 mm/a,respectively.The overall precipitation of Baihe station displayed an upward trend with a change rate of 0.080 mm/a,while that of Shayang station showed a downward trend with a change rate of -0.652 mm/a.The potential evapotranspiration exhibited a decreasing trend with the change rates of -1.403 mm/a and -1.793 mm/a,respectively. The abrupt change point of the annual runoff sequence at Baihe and Shayang stations was 1991,thus the period was divided into the base period (1964-1991) and the change period (1992-2015).Compared with the base period,the decreasing rates of rainfall and potential evapotranspiration in the change period of Baihe station was 4.72% and 1.11%,respectively,and those in Shayang station was 4.45% and 3.5%,respectively.The underlying surface parameters showed an upward trend compared with the base period,with an increased rate of 4167% and 2905%,respectively.The elastic coefficients of runoff to rainfall,potential evapotranspiration and underlying surface at Baihe station in the change period was 1.79,-0.79,-064,respectively,and those in Shayang station was 2.07,-1.07,-0.71,respectively,which indicated that the runoff at both stations is most sensitive to precipitation and least sensitive to an underlying surface. The underlying surface changes were the main factor of runoff change in the Hanjiang River basin,and its contribution rate to the runoff change at Baihe and Shayang stations was 74.67% and 76.37%,respectively;The contribution rate of precipitation to the runoff change at Baihe and Shayang stations took second place,and the contribution rate was 27.80% and 37.73%,respectively.Potential evapotranspiration had a negative contribution to runoff change at both stations,and the contribution rate was the lowest. The increasing annual precipitation at Baihe station,the hydrometeorological elements in the Hanjiang River basin generally showed a decreasing trend from 1964 to 2015.The underlying surface changes were the major controlling factor of runoff reduction in the Hanjiang River basin,and the normalized difference vegetation index in the change period was increased as a whole compared with the base period.The vegetation change was an important reason for the overall decrease of runoff in the Hanjiang River basin,and the influence of climate factors was relatively small. The complementary relationship method based on Budyko′s hydro-thermal coupling equilibrium equation is simple and practical,but the physical meaning and quantitative expression of the underlying surface parameter in this equation need to be further clarified.
In recent decades,global climate change,especially anthropogenic activities such as land use change and reservoir construction have led to profound changes in hydrological processes in basins.Therefore,runoff change and attribution analysis under changing environment have become a hot research area among domestic and overseas scholars .The elastic coefficient method based on Budyko hypothesis is an effective method for the attribution analysis of runoff change,but its calculation results have some errors.Therefore,the Hanjiang River basin,which is sensitive to climate change and where human activities are intense is selected as the research object.The contribution rate of climate change and underlying surface change to runoff variability was quantitatively decomposed by the complementary relationship method of Budyko hypothesis,to provide a scientific basis for water resources management and sustainable utilization. The linear trend estimation and the moving average method were used to analyze the change trends of hydrometeorological elements at Baihe and Shayang stations in the Hanjiang River basin based on the hydrometeorological data such as temperature,precipitation and runoff from 1964 to 2015.Mann-Kendall test and Pettitt test were used to detect the abrupt change points in the annual runoff series at two stations.Based on Budyko′shydro-thermal coupling equilibrium theory,the elastic coefficients of runoff were calculated,and the complementary relationship method was used to quantitatively distinguish the contribution rate of each influencing factor to runoff change.Finally,the influence of climate and vegetation cover change on runoff change was discussed. From 1964 to 2015,the runoff of Baihe and Shayang stations showed a decreasing trend,with the change rate of -2.797 mm/a and -1.875 mm/a,respectively.The overall precipitation of Baihe station displayed an upward trend with a change rate of 0.080 mm/a,while that of Shayang station showed a downward trend with a change rate of -0.652 mm/a.The potential evapotranspiration exhibited a decreasing trend with the change rates of -1.403 mm/a and -1.793 mm/a,respectively. The abrupt change point of the annual runoff sequence at Baihe and Shayang stations was 1991,thus the period was divided into the base period (1964-1991) and the change period (1992-2015).Compared with the base period,the decreasing rates of rainfall and potential evapotranspiration in the change period of Baihe station was 4.72% and 1.11%,respectively,and those in Shayang station was 4.45% and 3.5%,respectively.The underlying surface parameters showed an upward trend compared with the base period,with an increased rate of 4167% and 2905%,respectively.The elastic coefficients of runoff to rainfall,potential evapotranspiration and underlying surface at Baihe station in the change period was 1.79,-0.79,-064,respectively,and those in Shayang station was 2.07,-1.07,-0.71,respectively,which indicated that the runoff at both stations is most sensitive to precipitation and least sensitive to an underlying surface. The underlying surface changes were the main factor of runoff change in the Hanjiang River basin,and its contribution rate to the runoff change at Baihe and Shayang stations was 74.67% and 76.37%,respectively;The contribution rate of precipitation to the runoff change at Baihe and Shayang stations took second place,and the contribution rate was 27.80% and 37.73%,respectively.Potential evapotranspiration had a negative contribution to runoff change at both stations,and the contribution rate was the lowest. The increasing annual precipitation at Baihe station,the hydrometeorological elements in the Hanjiang River basin generally showed a decreasing trend from 1964 to 2015.The underlying surface changes were the major controlling factor of runoff reduction in the Hanjiang River basin,and the normalized difference vegetation index in the change period was increased as a whole compared with the base period.The vegetation change was an important reason for the overall decrease of runoff in the Hanjiang River basin,and the influence of climate factors was relatively small. The complementary relationship method based on Budyko′s hydro-thermal coupling equilibrium equation is simple and practical,but the physical meaning and quantitative expression of the underlying surface parameter in this equation need to be further clarified.
2021, 19(6):1125-1,135.
Abstract:
Under the increasingly severe contradiction between supply and demand of water resources,pressure of water resources shortage has become an urgent problem in China. Hu Line was taken as as the dividing line for the spatial heterogeneity of influencing factors of reclaimed water development and utilization in east and west regions.The structural equation model (SEM) was used to construct the mechanism framework of the driving-constrained non-recursive structure,to describe the conduction path of the influencing factors,and to quantify the contribution degree of the influencing factors. The factor load of reclaimed water development and utilization on the east side of Hu Line was 0.79,which indicated that the interpretation level of the latent variable of driving factor on reclaimed water development and utilization could reach 62.4%.A load of a latent variable factor of constraint factor was 0.36,which indicated that its interpretation level was about 13.0%.The variance interpretation of the remaining 24.6% reclaimed water development was an estimation error that could not be fully explained.The latent variables of constraint factors were more affected by engineering conditions,economic conditions,and technical level.The load of factors was above 0.85,and the latent variables of constraint factors were less affected by the latent variables of the water resources environment.By analyzing the structural model between the latent variable of driving factor and the latent variable of supply-side,the demand side,and comparing the correlation intensity between latent variables,it was found that the latent variable of supply-side had a strong on the latent variable of a driving factor,and the interpretation level reached to 70.6%.At the same time,through the directional correlation analysis between the demand-side and the supply-side latent variable,it was found that the demand-side latent variable had a negative on the supply-side latent variable,which indicated that the demand-side latent variable had less influence on the supply-side latent variable.The latent variable factor load of driving factors in the west side of Hu Line was 0.61,which indicated that the interpretation level of reclaimed water development and utilization was 37.2%.;A load of a latent variable factor of constraint factor was 0.71,which indicated that its interpretation level was about 50.4%.The remaining 12.4% of reclaimed water development uses variance interpretation as the estimated residual which could not be fully explained.The factor load coefficient of the latent variable of the constraint factor on the latent variable of class II,and found that the latent variable of the constraint factor was greatly affected by the engineering condition,the economic condition,and the water resources environment constraint,and the latent variable of the technical level had a weak influence on the latent variable of the constraint factor. The development and utilization of reclaimed water in the east side of Hu Line was greater than the restriction and had high-level development potential.The contribution rate of supply-side latent variables to the development and utilization of reclaimed water was 63.6%,and the contribution rate of demand-side latent variables was only 6.2%,which objectively reflected that a strong supply capacity of reclaimed water in the eastern region,but the demand for reclaimed water was not strong.The imperfection of the engineering conditions such as the supporting pipe network of reclaimed water was the leading constraint factor in the eastern region,and the contribution rate of its influence degree was 11.8%.The regional economic conditions and the level of sewage treatment technology were the secondary constraints,and their contribution rate was less than 10%. The restriction of reclaimed water development and utilization in the west side of Hu Line was higher than that of driving propulsion,and the ability of development and utilization was insufficient.The supply-side latent variable had the greatest influence on the development and utilization of reclaimed water in the west area with contribution rate 36.4%.On the contrary,the influence degree of demand-side latent variable was only 6.1%.The overall driving effect was insufficient.Environmental stress of regional water resources,imperfect construction of reclaimed water engineering facilities,and low level of regional economic development had a great influence on the development and utilization of reclaimed water,which were the leading factor,and the contribution rates of the influence degree were between 15.9% and 18.1%.The technical level of sewage treatment was a secondary constraint factor,and the contribution rate was 7.2%.
Under the increasingly severe contradiction between supply and demand of water resources,pressure of water resources shortage has become an urgent problem in China. Hu Line was taken as as the dividing line for the spatial heterogeneity of influencing factors of reclaimed water development and utilization in east and west regions.The structural equation model (SEM) was used to construct the mechanism framework of the driving-constrained non-recursive structure,to describe the conduction path of the influencing factors,and to quantify the contribution degree of the influencing factors. The factor load of reclaimed water development and utilization on the east side of Hu Line was 0.79,which indicated that the interpretation level of the latent variable of driving factor on reclaimed water development and utilization could reach 62.4%.A load of a latent variable factor of constraint factor was 0.36,which indicated that its interpretation level was about 13.0%.The variance interpretation of the remaining 24.6% reclaimed water development was an estimation error that could not be fully explained.The latent variables of constraint factors were more affected by engineering conditions,economic conditions,and technical level.The load of factors was above 0.85,and the latent variables of constraint factors were less affected by the latent variables of the water resources environment.By analyzing the structural model between the latent variable of driving factor and the latent variable of supply-side,the demand side,and comparing the correlation intensity between latent variables,it was found that the latent variable of supply-side had a strong on the latent variable of a driving factor,and the interpretation level reached to 70.6%.At the same time,through the directional correlation analysis between the demand-side and the supply-side latent variable,it was found that the demand-side latent variable had a negative on the supply-side latent variable,which indicated that the demand-side latent variable had less influence on the supply-side latent variable.The latent variable factor load of driving factors in the west side of Hu Line was 0.61,which indicated that the interpretation level of reclaimed water development and utilization was 37.2%.;A load of a latent variable factor of constraint factor was 0.71,which indicated that its interpretation level was about 50.4%.The remaining 12.4% of reclaimed water development uses variance interpretation as the estimated residual which could not be fully explained.The factor load coefficient of the latent variable of the constraint factor on the latent variable of class II,and found that the latent variable of the constraint factor was greatly affected by the engineering condition,the economic condition,and the water resources environment constraint,and the latent variable of the technical level had a weak influence on the latent variable of the constraint factor. The development and utilization of reclaimed water in the east side of Hu Line was greater than the restriction and had high-level development potential.The contribution rate of supply-side latent variables to the development and utilization of reclaimed water was 63.6%,and the contribution rate of demand-side latent variables was only 6.2%,which objectively reflected that a strong supply capacity of reclaimed water in the eastern region,but the demand for reclaimed water was not strong.The imperfection of the engineering conditions such as the supporting pipe network of reclaimed water was the leading constraint factor in the eastern region,and the contribution rate of its influence degree was 11.8%.The regional economic conditions and the level of sewage treatment technology were the secondary constraints,and their contribution rate was less than 10%. The restriction of reclaimed water development and utilization in the west side of Hu Line was higher than that of driving propulsion,and the ability of development and utilization was insufficient.The supply-side latent variable had the greatest influence on the development and utilization of reclaimed water in the west area with contribution rate 36.4%.On the contrary,the influence degree of demand-side latent variable was only 6.1%.The overall driving effect was insufficient.Environmental stress of regional water resources,imperfect construction of reclaimed water engineering facilities,and low level of regional economic development had a great influence on the development and utilization of reclaimed water,which were the leading factor,and the contribution rates of the influence degree were between 15.9% and 18.1%.The technical level of sewage treatment was a secondary constraint factor,and the contribution rate was 7.2%.
2021, 19(6):1136-1146.
Abstract:
The East Route of South-to-North Water Transfer Project diverts water from the Yangtze River through Jiangdu Water Conservancy Project.Accurate and timely water-level forecast of the diversion project plays a key role in the scientific operation of water conservancy project and reasonable allocation of water resources.The Sanjiangying tide station near the diversion project was selected as a representative.Due to the Sanjiangying tide station locating in the tidal limit,the water level was affected by a combination of astronomical tide and upstream inflow.The interval precipitation should be taken into consideration in the tidal level forecast since the precipitation was unevenly distributed throughout the year because of the unique subtropical monsoon climate.Due to the numerous influencing factors,the tidal level forecast of Sanjiangying can be more complicated. Tidal harmonic analysis method was used to forecast astronomical tide.The average daily tidal level and the hourly tidal level can be obtained by the tidal harmonic analysis method.Four methods,including secondary correction method,multiple linear regression method,support vector machine method and random forest method were applied to forecast the average daily tidal level of Sanjiangying station.The hourly tidal level forecast was based on the forecast of the average daily tidal level of the above four methods and the tidal harmonic analysis method.The precision index,including qualified rate,absolute error and root mean square error were used to compare the accuracy of four methods for average daily tidal level and hourly tidal level.Moreover,a linearly dependent coefficient was used to compare the degree of fitting between simulated tidal level and measured tidal level.Finally,the optimum forecasting scheme was recognized. The qualified rate of a simulated tidal level using tidal harmonic analysis method was too low to meet the actual engineering requirement and therefore other methods are needed to improve the forecast precision.The results of simulated average daily tidal level and simulated hourly tidal level showed that the accuracy of the simulated average daily tidal level determined the accuracy of simulated hourly tidal level.Better average daily tidal level forecast was followed by a better hourly tidal level forecast.In addition,the accuracy of the model training period was higher than the verification period,which was consistent with the assumption of the general case.The prediction accuracy of the average daily tidal level by four methods can reach class B or above in both the training period and verification period.Moreover,the precision index showed that secondary correction method owed the highest accuracy and stability with prediction accuracy reaching class A,followed by the support vector machine method,and the multiple linear regression method and random forest method had the relatively worst performance.The order was kept when forecasting the hourly tidal level,with secondary correction method also reaching class A.The result was also verified by linearly dependent coefficient;secondary correction method had the highest linearly dependent coefficient in the forecast of average daily tidal level and hourly tidal level,which means the simulated tidal level forecasted by secondary correction method was closer to the measured tidal level.Thus,it can be seen that secondary correction method was the best method to forecast tidal level in the four methods on account of its highest prediction accuracy and stability. Out of comprehensive consideration,secondary correction method is suitable for applying in the fine scheduling of the water conservancy project in contrast to support vector machine,multiple linear regression and random forests,which are more appropriately used for tidal level warning owing to longer prediction period.
The East Route of South-to-North Water Transfer Project diverts water from the Yangtze River through Jiangdu Water Conservancy Project.Accurate and timely water-level forecast of the diversion project plays a key role in the scientific operation of water conservancy project and reasonable allocation of water resources.The Sanjiangying tide station near the diversion project was selected as a representative.Due to the Sanjiangying tide station locating in the tidal limit,the water level was affected by a combination of astronomical tide and upstream inflow.The interval precipitation should be taken into consideration in the tidal level forecast since the precipitation was unevenly distributed throughout the year because of the unique subtropical monsoon climate.Due to the numerous influencing factors,the tidal level forecast of Sanjiangying can be more complicated. Tidal harmonic analysis method was used to forecast astronomical tide.The average daily tidal level and the hourly tidal level can be obtained by the tidal harmonic analysis method.Four methods,including secondary correction method,multiple linear regression method,support vector machine method and random forest method were applied to forecast the average daily tidal level of Sanjiangying station.The hourly tidal level forecast was based on the forecast of the average daily tidal level of the above four methods and the tidal harmonic analysis method.The precision index,including qualified rate,absolute error and root mean square error were used to compare the accuracy of four methods for average daily tidal level and hourly tidal level.Moreover,a linearly dependent coefficient was used to compare the degree of fitting between simulated tidal level and measured tidal level.Finally,the optimum forecasting scheme was recognized. The qualified rate of a simulated tidal level using tidal harmonic analysis method was too low to meet the actual engineering requirement and therefore other methods are needed to improve the forecast precision.The results of simulated average daily tidal level and simulated hourly tidal level showed that the accuracy of the simulated average daily tidal level determined the accuracy of simulated hourly tidal level.Better average daily tidal level forecast was followed by a better hourly tidal level forecast.In addition,the accuracy of the model training period was higher than the verification period,which was consistent with the assumption of the general case.The prediction accuracy of the average daily tidal level by four methods can reach class B or above in both the training period and verification period.Moreover,the precision index showed that secondary correction method owed the highest accuracy and stability with prediction accuracy reaching class A,followed by the support vector machine method,and the multiple linear regression method and random forest method had the relatively worst performance.The order was kept when forecasting the hourly tidal level,with secondary correction method also reaching class A.The result was also verified by linearly dependent coefficient;secondary correction method had the highest linearly dependent coefficient in the forecast of average daily tidal level and hourly tidal level,which means the simulated tidal level forecasted by secondary correction method was closer to the measured tidal level.Thus,it can be seen that secondary correction method was the best method to forecast tidal level in the four methods on account of its highest prediction accuracy and stability. Out of comprehensive consideration,secondary correction method is suitable for applying in the fine scheduling of the water conservancy project in contrast to support vector machine,multiple linear regression and random forests,which are more appropriately used for tidal level warning owing to longer prediction period.
2021, 19(6):1147-1156.
Abstract:
Multi-disciplinary and comprehensive water resources carrying capacity risk is a theoretical basis of water resources carrying risk identification,monitoring and early warning.It is not only a major scientific problem that must be solved for risk based water resources carrying management,but also prerequisite for fact management to risk management for water resources management. Water resources carrying capacity risk refers to the probability of water resources overload under various uncertain circumstances.Water resources carrying capacity risk monitoring and early warning need the support of water resources carrying capacity evaluation index system and methods.It needs to be reported according to the framework of risk evaluation.The constituent elements of risk are disaster-causing body and disaster-bearing body.The risk of water resources carrying is social and economic system.The vulnerability of water resources carrying risk mainly comes from the water resources system itself,including four dimensions of "quantity,quality,domain and flow",which refer to the amount of water resources allowed for economic and social consumption,the amount of pollutants allowed to be discharged into rivers and lakes,the surface water volume and groundwater level to maintain a certain water space,and the river ecological flow to maintain specific ecological functions.Water resources carrying risk monitoring and early warning is a threshold of water resources carrying risk category and level based on the evaluation results of water resources carrying capacity and state and the purpose is to build a multi-level early warning system from single index factor risk early warning to regional water resources carrying risk early warning,taking preventive measures and control the water resources pressure of economic and social development within the range of water resources system. A theoretical model coupling water resources carrying capacity state and risk monitoring and early warning level to point out the focus of water resources carrying risk monitoring and early warning and to determine the thresholds of different early warning degrees of four disaster causing factors in the theoretical model in combination with the process of regional socio-economic development.The indicator early warning method is used to design the alarm criteria and build a monitoring and early warning system framework composed of monitoring layer,early warning layer,decision-making layer and feedback regulation layer.The core task of the monitoring layer is to develop comprehensive,accurate and real-time water resources carrying information acquisition and processing technology,including information monitoring,data review and database construction.The early warning layer includes three levels:early warning method,early warning content and information release.To build a reasonable and effective early warning method for water resources carrying risk monitoring,including early warning model and alarm criteria.Both the decision-making layer and the feedback layer refer to the response of the water administrative department to the early warning information,and the decision-making layer focuses on the decision-making process of the water administrative department,which includes five levels:information exchange,expert evaluation,departmental consultation,decision-making and decision-making.The feedback layer focuses on the specific control of water resources carrying risk by the water administrative department,mainly including control measures and effect evaluation. Through the monitoring and warning system,information can be timely sent out,providing the regulation basis for decision-makers to reduce the risk of water resources carrying capacity and control social-economic water resources pressure within the acceptable range.Water resources carrying capacity risk is a new field of water resources carrying capacity.There are some differences in the connotation and characterization of water resources carrying capacity.So,there must be many scientific problems to be clarified in the monitoring and early warning of water resources carrying capacity risk.
Multi-disciplinary and comprehensive water resources carrying capacity risk is a theoretical basis of water resources carrying risk identification,monitoring and early warning.It is not only a major scientific problem that must be solved for risk based water resources carrying management,but also prerequisite for fact management to risk management for water resources management. Water resources carrying capacity risk refers to the probability of water resources overload under various uncertain circumstances.Water resources carrying capacity risk monitoring and early warning need the support of water resources carrying capacity evaluation index system and methods.It needs to be reported according to the framework of risk evaluation.The constituent elements of risk are disaster-causing body and disaster-bearing body.The risk of water resources carrying is social and economic system.The vulnerability of water resources carrying risk mainly comes from the water resources system itself,including four dimensions of "quantity,quality,domain and flow",which refer to the amount of water resources allowed for economic and social consumption,the amount of pollutants allowed to be discharged into rivers and lakes,the surface water volume and groundwater level to maintain a certain water space,and the river ecological flow to maintain specific ecological functions.Water resources carrying risk monitoring and early warning is a threshold of water resources carrying risk category and level based on the evaluation results of water resources carrying capacity and state and the purpose is to build a multi-level early warning system from single index factor risk early warning to regional water resources carrying risk early warning,taking preventive measures and control the water resources pressure of economic and social development within the range of water resources system. A theoretical model coupling water resources carrying capacity state and risk monitoring and early warning level to point out the focus of water resources carrying risk monitoring and early warning and to determine the thresholds of different early warning degrees of four disaster causing factors in the theoretical model in combination with the process of regional socio-economic development.The indicator early warning method is used to design the alarm criteria and build a monitoring and early warning system framework composed of monitoring layer,early warning layer,decision-making layer and feedback regulation layer.The core task of the monitoring layer is to develop comprehensive,accurate and real-time water resources carrying information acquisition and processing technology,including information monitoring,data review and database construction.The early warning layer includes three levels:early warning method,early warning content and information release.To build a reasonable and effective early warning method for water resources carrying risk monitoring,including early warning model and alarm criteria.Both the decision-making layer and the feedback layer refer to the response of the water administrative department to the early warning information,and the decision-making layer focuses on the decision-making process of the water administrative department,which includes five levels:information exchange,expert evaluation,departmental consultation,decision-making and decision-making.The feedback layer focuses on the specific control of water resources carrying risk by the water administrative department,mainly including control measures and effect evaluation. Through the monitoring and warning system,information can be timely sent out,providing the regulation basis for decision-makers to reduce the risk of water resources carrying capacity and control social-economic water resources pressure within the acceptable range.Water resources carrying capacity risk is a new field of water resources carrying capacity.There are some differences in the connotation and characterization of water resources carrying capacity.So,there must be many scientific problems to be clarified in the monitoring and early warning of water resources carrying capacity risk.
2021, 19(6):1157-1166.
Abstract:
Haihe River basin located in the north China plain,having serious threat of water shortage.To improve the current groundwater environment,the underground reservoir storage function should be fully utilized to use the groundwater funnel formed for many years by implementing the artificial and natural regulation and storage.In the central part of north China plain,soil properties are unfavorable to groundwater storage and surface water infiltration.A surface water infiltration test was carried out in the river belt to obtain the maximum underground storage space and provide a good strategy for the rational utilization of water resources. The infiltration test was carried out at Fanlu River,and the capacity of groundwater reservoir regulation and storage and the variation characteristics of groundwater level were studied by volume method and surface water infiltration test,which may provide a basis for water resource reserve planning in the Paleo-river area of north China plain.The experimental area of surface water infiltration was selected in the Nangong Gulu River,and monitoring data was obtained by artificial water diversion for 1.5 months,and the variation characteristics of groundwater level and water quantity and infiltration amount were studied. The results showed that the infiltration rate of the dry river reached 80.54%.The vertical seepage velocity of Ⅰ-Ⅰ′ and Ⅱ-Ⅱ′river section in the upper and lower reaches of the Suolu river was 10.81 m/d and 10.72 m/d,and the horizontal diffusion velocity was 1.69 m/h and 2.38 m/h.The vertical seepage velocity of Ⅰ-Ⅰ′ section was greater than that of Ⅱ-Ⅱ′section,and the horizontal diffusion velocity was less than that of Ⅱ-Ⅱ′,the water dome formed by Ⅰ-Ⅰ′section was more obvious than that of Ⅱ-Ⅱ′section,and it was not easy to dissipate.The calculation results showed that the storage capacity of the test area was 1.87×10.8 m3. Based on the analysis of groundwater level and water volume variation characteristics in the infiltration test of the Fanlu River,the following conclusions are drawn:(1)During the test,the penetration ratio was 80.54%.(2) Vertical permeation velocities at sections Ⅰ-Ⅰ′ and Ⅱ-Ⅱ′of the Fanlu River are 10.81 m/d and 10.72 m/d,which is related to the ratio of silt and silty clay in the aeration zone.The horizontal diffusion velocity of infiltrated water is 1.69 m/h and 2.38 m/h,which is related to the lithology of water level variation zone.(3)As the vertical penetration velocity of section Ⅰ-Ⅰ′ is greater than that of section Ⅱ-Ⅱ′and the horizontal diffusion velocity is lower than that of section Ⅱ-Ⅱ′,the formation of water dunes in section Ⅰ-Ⅰ′ is more obvious than that of section Ⅱ-Ⅱ′ and it is not easy to dissipate.(4) The change of water level in the monitoring hole is affected by both daily infiltration water volume and hydraulic gradient.The closer the monitoring hole to the infiltration field,the greater the influence of daily infiltration and hydraulic slope.(5) Groundwater reservoir total reservoir capacity is 3.21×10.8 m3,the storage capacity is 1.87×10.8 m3,and the empty storage capacity is 0.77×10.8 m3,respectively,which provides enough space for regional water resource storage.This study has a guiding significance for the selection of seepage site of Nangong groundwater reservoir and regional water resource regulation and storage and has certain reference significance for regional water resource regulation and storage through groundwater reservoir in north China.The deficiency of the research lies in the limitation of practical conditions,and the lack of monitoring holes of groundwater level has affected the integrity of groundwater dunes.It is suggested that the number of monitoring holes should be increased when conditions permit,to obtain more scientific test results.
Haihe River basin located in the north China plain,having serious threat of water shortage.To improve the current groundwater environment,the underground reservoir storage function should be fully utilized to use the groundwater funnel formed for many years by implementing the artificial and natural regulation and storage.In the central part of north China plain,soil properties are unfavorable to groundwater storage and surface water infiltration.A surface water infiltration test was carried out in the river belt to obtain the maximum underground storage space and provide a good strategy for the rational utilization of water resources. The infiltration test was carried out at Fanlu River,and the capacity of groundwater reservoir regulation and storage and the variation characteristics of groundwater level were studied by volume method and surface water infiltration test,which may provide a basis for water resource reserve planning in the Paleo-river area of north China plain.The experimental area of surface water infiltration was selected in the Nangong Gulu River,and monitoring data was obtained by artificial water diversion for 1.5 months,and the variation characteristics of groundwater level and water quantity and infiltration amount were studied. The results showed that the infiltration rate of the dry river reached 80.54%.The vertical seepage velocity of Ⅰ-Ⅰ′ and Ⅱ-Ⅱ′river section in the upper and lower reaches of the Suolu river was 10.81 m/d and 10.72 m/d,and the horizontal diffusion velocity was 1.69 m/h and 2.38 m/h.The vertical seepage velocity of Ⅰ-Ⅰ′ section was greater than that of Ⅱ-Ⅱ′section,and the horizontal diffusion velocity was less than that of Ⅱ-Ⅱ′,the water dome formed by Ⅰ-Ⅰ′section was more obvious than that of Ⅱ-Ⅱ′section,and it was not easy to dissipate.The calculation results showed that the storage capacity of the test area was 1.87×10.8 m3. Based on the analysis of groundwater level and water volume variation characteristics in the infiltration test of the Fanlu River,the following conclusions are drawn:(1)During the test,the penetration ratio was 80.54%.(2) Vertical permeation velocities at sections Ⅰ-Ⅰ′ and Ⅱ-Ⅱ′of the Fanlu River are 10.81 m/d and 10.72 m/d,which is related to the ratio of silt and silty clay in the aeration zone.The horizontal diffusion velocity of infiltrated water is 1.69 m/h and 2.38 m/h,which is related to the lithology of water level variation zone.(3)As the vertical penetration velocity of section Ⅰ-Ⅰ′ is greater than that of section Ⅱ-Ⅱ′and the horizontal diffusion velocity is lower than that of section Ⅱ-Ⅱ′,the formation of water dunes in section Ⅰ-Ⅰ′ is more obvious than that of section Ⅱ-Ⅱ′ and it is not easy to dissipate.(4) The change of water level in the monitoring hole is affected by both daily infiltration water volume and hydraulic gradient.The closer the monitoring hole to the infiltration field,the greater the influence of daily infiltration and hydraulic slope.(5) Groundwater reservoir total reservoir capacity is 3.21×10.8 m3,the storage capacity is 1.87×10.8 m3,and the empty storage capacity is 0.77×10.8 m3,respectively,which provides enough space for regional water resource storage.This study has a guiding significance for the selection of seepage site of Nangong groundwater reservoir and regional water resource regulation and storage and has certain reference significance for regional water resource regulation and storage through groundwater reservoir in north China.The deficiency of the research lies in the limitation of practical conditions,and the lack of monitoring holes of groundwater level has affected the integrity of groundwater dunes.It is suggested that the number of monitoring holes should be increased when conditions permit,to obtain more scientific test results.
2021, 19(6):1167-1,174.
Abstract:
Ice and water regime changed drastically due to frozen thaws in the break-up period in Inner Mongolia reach of the Yellow River,so it is difficult to forecast the flood and the accuracy is low.There are relatively few researches on ice flood forecasting methods,and most of the existing research methods focus on the flooding process under open flow condition.Due to the limitation of the measured data during the ice period,the research on ice floods is far from enough.The Muskingum method and its derivation method are suitable for the discharge routing under open flow conditions,but how to reflect the characteristics of discharge routing in ice flood season needs to be studied.Given the characteristics of the channel with unbalanced storage in the upstream and downstream channels,there is still no better solution in the derivative method of the Muskingum method. Based on the prototype observation of Inner Mongolia reach of the Yellow River and the measured discharge data during the ice period,the transformation process of ice and water during the freezing and thawing periods is analyzed,and the ice flood type is identified by the ice flood characteristics to predict the downstream discharge in advance.The discharge process of Inner Mongolia reach during the break-up period is calculated.The modified Muskingum method is used to calculate the flood routing by analogy with the river channel with tributaries.Considering the propagation time of discharge,channel-storage increment during the freezing period is added into the calculation to calculate the ice peak discharge during the break-up period. Compared with the flood in flood season,the ice flood occurred during the break-up period,the flood peak spread to the downstream not only did not flatten but also had a sudden change in the short term.When the temperature changes violently during the break-up period,the channel-storage increment is released in a short time.Channel-storage increment during the freezing period is considered,which can solve the problem of the increase of the channel storage in the prediction of discharge during the break-up period.Root mean square error,average absolute percentage error is used as the evaluation indexes of the prediction results.Compared with the measured discharge,root mean square error and average absolute percentage error of the calculated discharge reach the ideal accuracy,and the average absolute percentage error is less than 10.29%.The ice flood during the break-up period is mainly composed of ice dam flood and ice melting flood.According to the transformation process of ice and water and the characteristics of ice flood,it is found that the sudden change of discharge in ice flood season is mainly caused by ice dam flood.When ice dam flood occurs,the ice peak discharge increases along the way,with fast-rising rate,large amplitude,and large peak value.When ice melting flood occurs,the water potential is stable,and the discharge difference between upstream and downstream is small,and the ice peak discharge is small. During the break-up period,the increasing ice peak discharge from the upstream to the downstream can easily cause flood disasters along the river.The application of the modified Muskingum method can predict the sudden change of the downstream discharge,which has a good prediction effect on the discharge routing in ice flood season during the break-up period and greatly reduces the influence of ice regime and other uncertain factors on the prediction of ice flood process.The research results can provide a reference for the discharge forecast during the break-up period and the work of preventing and reducing disasters.In future,the influence of temperature and other factors on the discharge routing in ice flood season can be considered,and the relationship between temperature,channel-storage increment,and discharge can be further studied.
Ice and water regime changed drastically due to frozen thaws in the break-up period in Inner Mongolia reach of the Yellow River,so it is difficult to forecast the flood and the accuracy is low.There are relatively few researches on ice flood forecasting methods,and most of the existing research methods focus on the flooding process under open flow condition.Due to the limitation of the measured data during the ice period,the research on ice floods is far from enough.The Muskingum method and its derivation method are suitable for the discharge routing under open flow conditions,but how to reflect the characteristics of discharge routing in ice flood season needs to be studied.Given the characteristics of the channel with unbalanced storage in the upstream and downstream channels,there is still no better solution in the derivative method of the Muskingum method. Based on the prototype observation of Inner Mongolia reach of the Yellow River and the measured discharge data during the ice period,the transformation process of ice and water during the freezing and thawing periods is analyzed,and the ice flood type is identified by the ice flood characteristics to predict the downstream discharge in advance.The discharge process of Inner Mongolia reach during the break-up period is calculated.The modified Muskingum method is used to calculate the flood routing by analogy with the river channel with tributaries.Considering the propagation time of discharge,channel-storage increment during the freezing period is added into the calculation to calculate the ice peak discharge during the break-up period. Compared with the flood in flood season,the ice flood occurred during the break-up period,the flood peak spread to the downstream not only did not flatten but also had a sudden change in the short term.When the temperature changes violently during the break-up period,the channel-storage increment is released in a short time.Channel-storage increment during the freezing period is considered,which can solve the problem of the increase of the channel storage in the prediction of discharge during the break-up period.Root mean square error,average absolute percentage error is used as the evaluation indexes of the prediction results.Compared with the measured discharge,root mean square error and average absolute percentage error of the calculated discharge reach the ideal accuracy,and the average absolute percentage error is less than 10.29%.The ice flood during the break-up period is mainly composed of ice dam flood and ice melting flood.According to the transformation process of ice and water and the characteristics of ice flood,it is found that the sudden change of discharge in ice flood season is mainly caused by ice dam flood.When ice dam flood occurs,the ice peak discharge increases along the way,with fast-rising rate,large amplitude,and large peak value.When ice melting flood occurs,the water potential is stable,and the discharge difference between upstream and downstream is small,and the ice peak discharge is small. During the break-up period,the increasing ice peak discharge from the upstream to the downstream can easily cause flood disasters along the river.The application of the modified Muskingum method can predict the sudden change of the downstream discharge,which has a good prediction effect on the discharge routing in ice flood season during the break-up period and greatly reduces the influence of ice regime and other uncertain factors on the prediction of ice flood process.The research results can provide a reference for the discharge forecast during the break-up period and the work of preventing and reducing disasters.In future,the influence of temperature and other factors on the discharge routing in ice flood season can be considered,and the relationship between temperature,channel-storage increment,and discharge can be further studied.
2021, 19(6):1175-1,183.
Abstract:
Da′an City is located in the northwestern part of Jilin Province,an important grain-producing and also a water-scarce area.50% of the land surface in Da′an City is covered by arable land,and relies on groundwater irrigation.Under water supply and demand contradiction ,Da′an City urgently needs a convenient and reliable method to quickly grasp the distribution of local groundwater sustainability and guidelines for future groundwater management.Considering the complexity of numerical simulation methods a new method is needed to take the advantage of sufficient available groundwater level data which can be competent for smallscale groundwater sustainability. An artificial mining response-based groundwater sustainability index (AGSI) was proposed to highlights the impact of human mining activities on groundwater dynamics.The entropy TOPSIS method is used to determine the artificial mining degree of groundwater according to the data of groundwater exploitation in the study area.To achieve a spatial difference,it is necessary to decompose the pressure exerted by artificial mining on groundwater sustainability in each monitoring well through the decomposition coefficient,that could be correlated with the groundwater response state.Inverse distance weight interpolation method is used in ArcGIS to complete the conversion of AGSI value from point to surface. The average AGSI value of the whole aquifer,the Quaternary phreatic water and confined water,and the sustainability level subzones of each aquifer were obtained.Confined water was the main exploitation water source in the study area,and the analysis showed that the changing trend of the average AGSI value was the same as that of the exploited volume,indicating that the sustainability of confined water was significantly affected by it.The average AGSI value of phreatic water was similar to the trend of precipitation and was slightly affected by the amount of exploitation.Confined water′s average AGSI value was higher than that of phreatic water until 2015,and it continued to fall below phreatic water subsequent years due to unreasonable exploitation.The value of phreatic water increased with a trend of 0.01/a and the confined water decreased with a trend of 0.04/aindicate that the risk of damage to groundwater sustainability was shifting from phreatic water to confined water.This trend was not significant at 95% confidence level.The coverage rate of "Low" sustainability subzone of phreatic water reached its maximum value of 45.2% in 2010,because dry climate promoted evaporation that year,while the coverage rate of "Low" sustainability subzone of confined water reached its maximum value of 32.5% in 2017,which was related to the increasing mining volume in recent years. The average AGSI value obtained by the AGSI method can better quantify the overall state of a certain type of water body sustainability.The process of groundwater sustainability changing with time,helps to detect sudden increases and decreases of sustainability in time,and guides managers to implement correct plans to encourage or restrict extraction.This also reflects the multi-year trend and change rate of sustainability to identify the management objects that should be focused on to improve groundwater sustainability.The sustainability level subzones drawn by the AGSI method indicate that the development potential areas and mining protection areas of different types of groundwater consistent with the multi-year dynamic situation of groundwater level.The groundwater sustainability evaluated by this method pays more attention to the effect of human exploitation,and the evaluation results are more suitable for guiding exploitation activities.
Da′an City is located in the northwestern part of Jilin Province,an important grain-producing and also a water-scarce area.50% of the land surface in Da′an City is covered by arable land,and relies on groundwater irrigation.Under water supply and demand contradiction ,Da′an City urgently needs a convenient and reliable method to quickly grasp the distribution of local groundwater sustainability and guidelines for future groundwater management.Considering the complexity of numerical simulation methods a new method is needed to take the advantage of sufficient available groundwater level data which can be competent for smallscale groundwater sustainability. An artificial mining response-based groundwater sustainability index (AGSI) was proposed to highlights the impact of human mining activities on groundwater dynamics.The entropy TOPSIS method is used to determine the artificial mining degree of groundwater according to the data of groundwater exploitation in the study area.To achieve a spatial difference,it is necessary to decompose the pressure exerted by artificial mining on groundwater sustainability in each monitoring well through the decomposition coefficient,that could be correlated with the groundwater response state.Inverse distance weight interpolation method is used in ArcGIS to complete the conversion of AGSI value from point to surface. The average AGSI value of the whole aquifer,the Quaternary phreatic water and confined water,and the sustainability level subzones of each aquifer were obtained.Confined water was the main exploitation water source in the study area,and the analysis showed that the changing trend of the average AGSI value was the same as that of the exploited volume,indicating that the sustainability of confined water was significantly affected by it.The average AGSI value of phreatic water was similar to the trend of precipitation and was slightly affected by the amount of exploitation.Confined water′s average AGSI value was higher than that of phreatic water until 2015,and it continued to fall below phreatic water subsequent years due to unreasonable exploitation.The value of phreatic water increased with a trend of 0.01/a and the confined water decreased with a trend of 0.04/aindicate that the risk of damage to groundwater sustainability was shifting from phreatic water to confined water.This trend was not significant at 95% confidence level.The coverage rate of "Low" sustainability subzone of phreatic water reached its maximum value of 45.2% in 2010,because dry climate promoted evaporation that year,while the coverage rate of "Low" sustainability subzone of confined water reached its maximum value of 32.5% in 2017,which was related to the increasing mining volume in recent years. The average AGSI value obtained by the AGSI method can better quantify the overall state of a certain type of water body sustainability.The process of groundwater sustainability changing with time,helps to detect sudden increases and decreases of sustainability in time,and guides managers to implement correct plans to encourage or restrict extraction.This also reflects the multi-year trend and change rate of sustainability to identify the management objects that should be focused on to improve groundwater sustainability.The sustainability level subzones drawn by the AGSI method indicate that the development potential areas and mining protection areas of different types of groundwater consistent with the multi-year dynamic situation of groundwater level.The groundwater sustainability evaluated by this method pays more attention to the effect of human exploitation,and the evaluation results are more suitable for guiding exploitation activities.
2021, 19(6):1184-1,193.
Abstract:
A serious degradation and significant decrease in wetlands areas in Sanjiang Plain of China have been reported.Water shortage is the key cause of wetland degradation.The natural inflow can not meet the actual water demand of wetland.Thus,it is imperative to replenishment the ecological water of the wetland.There may be conflicts between ecological and agricultural water use in the region,and water resources are preferentially used for agriculture in the region.Therefore,it is necessary to select the appropriate location and timing of water replenishment to make a planned water replenishment,to limit the ecological water resources that can be used to the maximum extent and the wetland can achieve better water replenishment effect.It requires the study of ecological water replenishment schemes based on water replenishment effect analysis. The characteristics of regional water demand and the surrounding hydraulic connection were analyzed,and the reasonable water replenishment period and location were selected to design the water replenishment scheme.Three water replenishment schemes were determined;one-time water replenishment in April (scheme 1),monthly water replenishment on demand from April to October (scheme 2),and staged water replenishment in April and July (scheme 3).MIKE 21 water flow evolution model was constructed through grid division,terrain interpolation,roughness selection,boundary setting,model verification,and other processes to realize the water flow evolution simulation of ecological water replenishment process in Sanhuanpao wetland,and to show the dynamic change process of water replenishment area and water depth.The GIS platform was used for numerical statistics and analysis of the wetland water replenishment effect. In schemes 1 and 3,the water replenishment flow was large and the spread was fast due to the relatively concentrated water replenishment.The flow had flowed to most wetland swamps areas containing the core areas I and II of the wetland before the period of large water demand from May to July.In scheme 2,due to the small amount of water supply on demand each month,the diffusion of small flow could not supply the wetland in time due to a certain lag.Before July,the water area and water depth are small,and the water demand process and water supply process are not synchronized due to the delay of water supply spread.In scheme 1,the water depth in the low-lying area was large in a short time,and a large amount of water supply caused the inundation of some central and northeastern cultivated land,while schemes 2 and 3 did not cause the inundation.The water area of the wetland increased significantly after water replenishment under the three schemes.The water replenishment areas of schemes 1 and 3 exceeded 20 000 hm2 in May,and it could be considered that the water flow had flowed into the whole protected area.Subsequently,the water area of scheme 1 decreased gradually due to evaporation,and the water area of scheme 3 was larger as a whole after water replenishment again.However,the water flow spread in scheme 2 was lagging,the water area increased gradually after water replenishment,and the water area was small in the early stage.Until July,the water area reached a large range,which is about 16 000 hm2.In terms of water depth,scheme 1 had a larger water depth in many areas,and the water depth in most areas of the eastern and western core areas of the reserve was more than 0.4 m.The water depth in different areas was quite different.After concentrated replenishment in April,the water depths of core areas I and II increased rapidly from April to July,reaching 0.62 m and 0.46 m,respectively,which may cause damage to some animal and plant habitats.In scheme 2,the water depth of the wetland increased slowly after monthly replenishment.Before July,the water depth of the two core areas was basically below 0.20 m,which was not enough to meet the water requirements of major birds and vegetation.In the later stage of replenishment,the water depth of more areas was distributed in 0.1-0.2 m,and the distribution of different water depths was gradually uniform.In scheme 3,the water depth increased from April to mid-May,and the water depths in the core areas I and II increased to 0.35 m and 0.28 m,respectively.The water depths in the two areas decreased from the end of the first replenishment to August,and the water depths increased to 0.44 m and 0.30 m,respectively,after the second replenishment.The water depth decreased again due to evaporation consumption.The process could meet the requirements of the suitable water depth for the rare waterfowl and dominant vegetation in the Sanhuanpao wetland. The staged water replenishment scheme in April and July has the best simulation effect.Under three schemes,the average water area of scheme 3 is the largest,which is closer to the recovery target,followed by scheme 1 and scheme 2.In scheme 2,the ondemand replenishment flow has a long spread time,and the process of water demand and replenishment is not synchronized.schemes 1 and 3 can replenishment the water demand of wetland to the water demand area in time,which can overcome the problem of flow hysteresis.However,one-time replenishment of scheme 1 will cause inundation of surrounding irrigation areas,and there are more areas with lower and higher water depths,and the spatial and temporal distribution of different water depths is uneven.The M-type characteristics of water demand process are more consistent under the staged replenishment scheme in April and July.By analyzing the suitable water depth range of rare waterfowl and dominant vegetation in the core area,the change process of water depth after water replenishment in this scheme can better meet the suitable living conditions of organisms in the region and create a suitable habitat environment.
A serious degradation and significant decrease in wetlands areas in Sanjiang Plain of China have been reported.Water shortage is the key cause of wetland degradation.The natural inflow can not meet the actual water demand of wetland.Thus,it is imperative to replenishment the ecological water of the wetland.There may be conflicts between ecological and agricultural water use in the region,and water resources are preferentially used for agriculture in the region.Therefore,it is necessary to select the appropriate location and timing of water replenishment to make a planned water replenishment,to limit the ecological water resources that can be used to the maximum extent and the wetland can achieve better water replenishment effect.It requires the study of ecological water replenishment schemes based on water replenishment effect analysis. The characteristics of regional water demand and the surrounding hydraulic connection were analyzed,and the reasonable water replenishment period and location were selected to design the water replenishment scheme.Three water replenishment schemes were determined;one-time water replenishment in April (scheme 1),monthly water replenishment on demand from April to October (scheme 2),and staged water replenishment in April and July (scheme 3).MIKE 21 water flow evolution model was constructed through grid division,terrain interpolation,roughness selection,boundary setting,model verification,and other processes to realize the water flow evolution simulation of ecological water replenishment process in Sanhuanpao wetland,and to show the dynamic change process of water replenishment area and water depth.The GIS platform was used for numerical statistics and analysis of the wetland water replenishment effect. In schemes 1 and 3,the water replenishment flow was large and the spread was fast due to the relatively concentrated water replenishment.The flow had flowed to most wetland swamps areas containing the core areas I and II of the wetland before the period of large water demand from May to July.In scheme 2,due to the small amount of water supply on demand each month,the diffusion of small flow could not supply the wetland in time due to a certain lag.Before July,the water area and water depth are small,and the water demand process and water supply process are not synchronized due to the delay of water supply spread.In scheme 1,the water depth in the low-lying area was large in a short time,and a large amount of water supply caused the inundation of some central and northeastern cultivated land,while schemes 2 and 3 did not cause the inundation.The water area of the wetland increased significantly after water replenishment under the three schemes.The water replenishment areas of schemes 1 and 3 exceeded 20 000 hm2 in May,and it could be considered that the water flow had flowed into the whole protected area.Subsequently,the water area of scheme 1 decreased gradually due to evaporation,and the water area of scheme 3 was larger as a whole after water replenishment again.However,the water flow spread in scheme 2 was lagging,the water area increased gradually after water replenishment,and the water area was small in the early stage.Until July,the water area reached a large range,which is about 16 000 hm2.In terms of water depth,scheme 1 had a larger water depth in many areas,and the water depth in most areas of the eastern and western core areas of the reserve was more than 0.4 m.The water depth in different areas was quite different.After concentrated replenishment in April,the water depths of core areas I and II increased rapidly from April to July,reaching 0.62 m and 0.46 m,respectively,which may cause damage to some animal and plant habitats.In scheme 2,the water depth of the wetland increased slowly after monthly replenishment.Before July,the water depth of the two core areas was basically below 0.20 m,which was not enough to meet the water requirements of major birds and vegetation.In the later stage of replenishment,the water depth of more areas was distributed in 0.1-0.2 m,and the distribution of different water depths was gradually uniform.In scheme 3,the water depth increased from April to mid-May,and the water depths in the core areas I and II increased to 0.35 m and 0.28 m,respectively.The water depths in the two areas decreased from the end of the first replenishment to August,and the water depths increased to 0.44 m and 0.30 m,respectively,after the second replenishment.The water depth decreased again due to evaporation consumption.The process could meet the requirements of the suitable water depth for the rare waterfowl and dominant vegetation in the Sanhuanpao wetland. The staged water replenishment scheme in April and July has the best simulation effect.Under three schemes,the average water area of scheme 3 is the largest,which is closer to the recovery target,followed by scheme 1 and scheme 2.In scheme 2,the ondemand replenishment flow has a long spread time,and the process of water demand and replenishment is not synchronized.schemes 1 and 3 can replenishment the water demand of wetland to the water demand area in time,which can overcome the problem of flow hysteresis.However,one-time replenishment of scheme 1 will cause inundation of surrounding irrigation areas,and there are more areas with lower and higher water depths,and the spatial and temporal distribution of different water depths is uneven.The M-type characteristics of water demand process are more consistent under the staged replenishment scheme in April and July.By analyzing the suitable water depth range of rare waterfowl and dominant vegetation in the core area,the change process of water depth after water replenishment in this scheme can better meet the suitable living conditions of organisms in the region and create a suitable habitat environment.
2021, 19(6):1194-1,207.
Abstract:
The Shandong Peninsula has become one of the most serious nitrate pollution region in China.Excess fertilization in the surface is a main reason of groundwater nitrate pollution.Because of the complex transportation and transformation processes of nitrogen in the unsaturated zone and saturated zone,numerical models can be served as useful tool to understand the influences of fertilization on groundwater pollution.The studies of fully coupled unsaturatedsaturated model with reactions is lacked at present. A three-dimensional fully coupled unsaturated-saturated numerical model of groundwater dynamic and solute transport was established.The reaction processes of nitrogen mineralization,nitrification and denitrification were added in the model,and COMSOL was used to solve the model.The model was applied to the Xiaogu River area of Shandong Peninsula,and verified by the monitoring data of groundwater level and nitrogen concentrations.Several scenarios of different pumping irrigation amounts,fertilizing amounts and crop types were simulated to analyze their influences on distribution of nitrogen in groundwater.The long-term enrichment process of nitrogen in groundwater was also predicted by the model. The results showed that the fully coupled unsaturated-saturated model could accurately simulate the groundwater dynamics and solute transportationtransformation process.Under normal irrigation and fertilization conditions,the water level changes were closely related to seasonal changes and agriculture activities,and the concentrations of nitrate and DON in groundwater were closely related to the fertilization time.When the pumping irrigation amount decreased 10% and 20%,the water level increased 0.04 m and 0.06 m on average,and the nitrate mass concentration decreased 2.17 mg/L and 2.98 mg/L,and the ammonia nitrogen mass concentration decreased 0.02 mg/L and 0.03 mg/L,respectively.When the fertilization increased 25% and decreased 25%,nitrate mass concentration in groundwater increased 2.60 mg/L and decreased 3.16 mg/L,and the ammonia nitrogen mass concentration increased 0.02 mg/L and decreased 0.02 mg/L,respectively.There was no linear relationship between the increase of nitrate mass concentration and the increase of the fertilization.When the summer cornwinter wheat rotation farmland was changed to vegetable farmland,the nitrate mass concentration increased 23.93 mg/L,and the ammonia nitrogen mass concentration increased 0.29 mg/L and a large amount of DON remained in the soil layer.Under long term normal fertilization conditions,the nitrate mass concentration gradually increased,the average increase in 5 years was 13.64 mg/L.On the contrary,under long term no fertilization conditions,the nitrate mass concentration decreased 33.48 mg/L in 5 years.Without the input of agricultural pollution sources,the nitrate mass concentrations of each region were lower than that of normal fertilization scenarios,especially in the southeast region. It was showed that the pumping irrigation and fertilization influence the groundwater nitrate pollution,which choud provide valuable scientific reference for groundwater resource managements and water pollution control.In future studies,the model can be applied to different regions and more farmland management measures can be simulated to show their influences on groundwater nitrogen pollution.
The Shandong Peninsula has become one of the most serious nitrate pollution region in China.Excess fertilization in the surface is a main reason of groundwater nitrate pollution.Because of the complex transportation and transformation processes of nitrogen in the unsaturated zone and saturated zone,numerical models can be served as useful tool to understand the influences of fertilization on groundwater pollution.The studies of fully coupled unsaturatedsaturated model with reactions is lacked at present. A three-dimensional fully coupled unsaturated-saturated numerical model of groundwater dynamic and solute transport was established.The reaction processes of nitrogen mineralization,nitrification and denitrification were added in the model,and COMSOL was used to solve the model.The model was applied to the Xiaogu River area of Shandong Peninsula,and verified by the monitoring data of groundwater level and nitrogen concentrations.Several scenarios of different pumping irrigation amounts,fertilizing amounts and crop types were simulated to analyze their influences on distribution of nitrogen in groundwater.The long-term enrichment process of nitrogen in groundwater was also predicted by the model. The results showed that the fully coupled unsaturated-saturated model could accurately simulate the groundwater dynamics and solute transportationtransformation process.Under normal irrigation and fertilization conditions,the water level changes were closely related to seasonal changes and agriculture activities,and the concentrations of nitrate and DON in groundwater were closely related to the fertilization time.When the pumping irrigation amount decreased 10% and 20%,the water level increased 0.04 m and 0.06 m on average,and the nitrate mass concentration decreased 2.17 mg/L and 2.98 mg/L,and the ammonia nitrogen mass concentration decreased 0.02 mg/L and 0.03 mg/L,respectively.When the fertilization increased 25% and decreased 25%,nitrate mass concentration in groundwater increased 2.60 mg/L and decreased 3.16 mg/L,and the ammonia nitrogen mass concentration increased 0.02 mg/L and decreased 0.02 mg/L,respectively.There was no linear relationship between the increase of nitrate mass concentration and the increase of the fertilization.When the summer cornwinter wheat rotation farmland was changed to vegetable farmland,the nitrate mass concentration increased 23.93 mg/L,and the ammonia nitrogen mass concentration increased 0.29 mg/L and a large amount of DON remained in the soil layer.Under long term normal fertilization conditions,the nitrate mass concentration gradually increased,the average increase in 5 years was 13.64 mg/L.On the contrary,under long term no fertilization conditions,the nitrate mass concentration decreased 33.48 mg/L in 5 years.Without the input of agricultural pollution sources,the nitrate mass concentrations of each region were lower than that of normal fertilization scenarios,especially in the southeast region. It was showed that the pumping irrigation and fertilization influence the groundwater nitrate pollution,which choud provide valuable scientific reference for groundwater resource managements and water pollution control.In future studies,the model can be applied to different regions and more farmland management measures can be simulated to show their influences on groundwater nitrogen pollution.
2021, 19(6):1208-1,216.
Abstract:
Yongding River is one of the seven major water systems in the Haihe River basin.The canyon section refers to the section from the dam of Guanting reservoir to the Sanjiadian barrage.Affected by the reduction of rainfall and the impoundment of the upstream Guanting reservoir,the runoff of Yongding River is reduced and the flow below Sanjiadian is cut off.To restore the ecological environment of Yongding River basin,the state and local governments have taken a series of measures such as ecological water replenishment.The ecological water replenishment has been carried out three times in 2019 and 2020 inYongding River .The leakage characteristics of the canyon section of Yongding River are analyzed and summarized under the specific mode of the three ecological water replenishment,to provide preliminary basic support for optimizing the allocation of water resources and formulating a scientific and reasonable water replenishment scheme. According to the different flow paths of ecological water replenishment and the discharge flow of the upstream section,the process of three ecological water replenishment is divided into different stages,and then the canyon section is further divided into three small sections based on collected flow of hydrological observation stations.Using the flow balance method,the leakage loss rate and leakage loss flow of each small section in each stage are calculated,and the proportion of leakage in each small section in the canyon section is obtained to analyze the causes of the leakage characteristics. [JP+3]Under the influence of different flow duration and discharge flow,the leakage loss flow and loss rate are different.The leakage loss rates of three water replenishments are 29.99%,24.67% and 20.62% respectively,showing a gradually decreasing trend.There is no obvious correlation between the leakage loss flow of the channel in the gorge section and the discharge flow of the Guanting reservoir.The length from Guanting reservoir (under the dam) to Luopoling reservoir is about 70% of the canyon section and the leakage loss flow accounts for about 30%.The length from the Loupoling reservoir to the Sanjiadian barrage is about 30% of the canyon section and the leakage accounts for about 70%.The length of the section from Loupoling reservoir to Xiaweidian hydropower station is about 14% of the canyon section and the leakage accounts for about 60%.The length from Xiaweidian hydropower station to the Sanjiadian barrage is about 16% of the canyon section and the leakage accounts for about 10%. The leakage loss rate of the three ecological recharges gradually decreases,ranging from 20% to 30%,i.e.the water recovery rate of the Sanjiadian barrage is 70%~80%.The section from Luopoling reservoir to Xiaweidian hydropower station is the main leakage section of the current canyon section of Yongding River,and its leakage loss flow accounts for about 60% of the canyon section.This section is located in the Cambrian Ordovician limestone stratum.Affected by the cutting of Jiulong Mountain-Xiangyu Daliang syncline and Yongding River fault,the karst caves and fissures in the bedrock are strongly developed,and there may be a "skylight" area in direct contact with the Quaternary groundwater,resulting in strong river permeability and large leakage loss flow,which constitute the internal cause of the hydrogeological conditions of the leakage characteristics.The external cause of the leakage characteristics is the river channel from Xiaweidian hydropower station to Sanjiadian barrage.
Yongding River is one of the seven major water systems in the Haihe River basin.The canyon section refers to the section from the dam of Guanting reservoir to the Sanjiadian barrage.Affected by the reduction of rainfall and the impoundment of the upstream Guanting reservoir,the runoff of Yongding River is reduced and the flow below Sanjiadian is cut off.To restore the ecological environment of Yongding River basin,the state and local governments have taken a series of measures such as ecological water replenishment.The ecological water replenishment has been carried out three times in 2019 and 2020 inYongding River .The leakage characteristics of the canyon section of Yongding River are analyzed and summarized under the specific mode of the three ecological water replenishment,to provide preliminary basic support for optimizing the allocation of water resources and formulating a scientific and reasonable water replenishment scheme. According to the different flow paths of ecological water replenishment and the discharge flow of the upstream section,the process of three ecological water replenishment is divided into different stages,and then the canyon section is further divided into three small sections based on collected flow of hydrological observation stations.Using the flow balance method,the leakage loss rate and leakage loss flow of each small section in each stage are calculated,and the proportion of leakage in each small section in the canyon section is obtained to analyze the causes of the leakage characteristics. [JP+3]Under the influence of different flow duration and discharge flow,the leakage loss flow and loss rate are different.The leakage loss rates of three water replenishments are 29.99%,24.67% and 20.62% respectively,showing a gradually decreasing trend.There is no obvious correlation between the leakage loss flow of the channel in the gorge section and the discharge flow of the Guanting reservoir.The length from Guanting reservoir (under the dam) to Luopoling reservoir is about 70% of the canyon section and the leakage loss flow accounts for about 30%.The length from the Loupoling reservoir to the Sanjiadian barrage is about 30% of the canyon section and the leakage accounts for about 70%.The length of the section from Loupoling reservoir to Xiaweidian hydropower station is about 14% of the canyon section and the leakage accounts for about 60%.The length from Xiaweidian hydropower station to the Sanjiadian barrage is about 16% of the canyon section and the leakage accounts for about 10%. The leakage loss rate of the three ecological recharges gradually decreases,ranging from 20% to 30%,i.e.the water recovery rate of the Sanjiadian barrage is 70%~80%.The section from Luopoling reservoir to Xiaweidian hydropower station is the main leakage section of the current canyon section of Yongding River,and its leakage loss flow accounts for about 60% of the canyon section.This section is located in the Cambrian Ordovician limestone stratum.Affected by the cutting of Jiulong Mountain-Xiangyu Daliang syncline and Yongding River fault,the karst caves and fissures in the bedrock are strongly developed,and there may be a "skylight" area in direct contact with the Quaternary groundwater,resulting in strong river permeability and large leakage loss flow,which constitute the internal cause of the hydrogeological conditions of the leakage characteristics.The external cause of the leakage characteristics is the river channel from Xiaweidian hydropower station to Sanjiadian barrage.
2021, 19(6):1217-1,226.
Abstract:
The water retaining structures built along rivers,canals,lakes,and coasts are called dikes,the earliest and widely used important flood control projects in the world.China has built more than 300,000 km of dikes above grade 5,which has played an important role in preventing floods and protecting people′s personal and property safety.Due to the problems of the low construction standard,poor quality and unstable foundation of some dikes,serious dangerous situations such as piping,landslide,bank collapse,and overflowing may even lead to dike breakin operation.Therefore,it is of great significance to evaluate the safety of the dike regularly and grasp the safety situation of the dike in time,to strengthen the management of the dike.Thus,dike safety evaluation was still mainly qualitative evaluation,lack of quantitative evaluation,so it is necessary to conduct more indepth research. Some studies only considered the influence of a single factor or much dependent on subjective experience of experts,which was not comprehensive and systematic,and there were few fuzzy and probabilistic studies considering the influencing factors of dike safety.Because dike safety is a multi-level,uncertain,and nonlinear dynamic system affected by many factors.The research on its evaluation method has always been a very complex problem.General numerical simulation,traditional standard evaluation and other methods were difficult to fully reflect the actual safety of dikes.The theory of cloud model evaluation method can comprehensively consider the fuzziness and probability characteristics of the evaluated object,and this theory has been widely used in all kinds of complex comprehensive evaluation research.Therefore,the cloud model theory was introduced into the dike safety evaluation.Based on the current relevant norms of dike safety evaluation,a hierarchical index system was constructed,which was composed of 5 first-level evaluation indexes,22 second-level evaluation indexes and 11 third-level evaluation indexes.Concerning the rating standards of the existing dike safety evaluation standards,based on the results of on-site quality inspection and safety review,the factors affecting dike safety were comprehensively considered through expert group decision-making.Each expert was given weight through the similarity of order relation to reflect the difference of different experts′ knowledge and experience.The traditional G1 method was improved,and the subjective weight of the index was calculated.The weight of the expert was calculated by entropy weight method to make the weight distribution of each index more scientific and reasonable.The corresponding three safety categories of dike safety were assigned to the corresponding scale interval and transformed into the corresponding safety cloud comments,and then the cloud comments of the third level evaluation index were determined by integrating expert opinions,and the floating cloud or integrated cloud computing model was used to fuse the cloud comments of different experts step by step.The total target cloud parameters of the dike safety state were obtained,and the corresponding cloud map was made,and the real safety state distribution of the dike was intuitively obtained.Based on this,the safety category was determined,and the development trend of the dike safety state was analyzed. Taking a dike on the left side of the Pearl River Channel as an example,the cloud evaluation of the third-level evaluation index was calculated using floating cloud,and the cloud parameters of the first-level index were obtained.The operation and management was rated as "unsafe" because of the great deficiency in the daily management and maintenance and safety monitoring of the dike,and the flood control capacity was rated as "unsafe" because the elevation of the dike was lower than the requirements of the design standards..Although the project quality was "basic safety",but the score is low,some "cloud droplets" fall into the "unsafe" scope.The main reason was that the dike took a long time to be completed and the construction standard was low.After many years of operation,the cross-section of the dike body,the clay content of the dike soil,the hidden danger of the dike body and the quality of slope protection have the problems of reduced safety,and the index value was on the low side.According to the cloud parameters of the first-level index and its corresponding combination optimization weight and overall goal of comprehensive cloud computing,the security state cloud map falls into the "basic security" range and was identified as the second-class dike,which was consistent with the conclusion of the traditional method of dike identification. The weight distribution of each index was optimized based on the scientific index system construction and combination weighting method,and the fuzziness and randomness of the influencing factors of dike safety were better combined by introducing cloud model theory.It is not only given a more accurate judgment of each state but also transforms the grade evaluation of dike safety into fuzzy and random comprehensive evaluation,compared with the traditional evaluation method.It can reflect the actual safety state of the dike more comprehensively,and provide a more scientific and reasonable basis for dike safety evaluation and strengthening management.
The water retaining structures built along rivers,canals,lakes,and coasts are called dikes,the earliest and widely used important flood control projects in the world.China has built more than 300,000 km of dikes above grade 5,which has played an important role in preventing floods and protecting people′s personal and property safety.Due to the problems of the low construction standard,poor quality and unstable foundation of some dikes,serious dangerous situations such as piping,landslide,bank collapse,and overflowing may even lead to dike breakin operation.Therefore,it is of great significance to evaluate the safety of the dike regularly and grasp the safety situation of the dike in time,to strengthen the management of the dike.Thus,dike safety evaluation was still mainly qualitative evaluation,lack of quantitative evaluation,so it is necessary to conduct more indepth research. Some studies only considered the influence of a single factor or much dependent on subjective experience of experts,which was not comprehensive and systematic,and there were few fuzzy and probabilistic studies considering the influencing factors of dike safety.Because dike safety is a multi-level,uncertain,and nonlinear dynamic system affected by many factors.The research on its evaluation method has always been a very complex problem.General numerical simulation,traditional standard evaluation and other methods were difficult to fully reflect the actual safety of dikes.The theory of cloud model evaluation method can comprehensively consider the fuzziness and probability characteristics of the evaluated object,and this theory has been widely used in all kinds of complex comprehensive evaluation research.Therefore,the cloud model theory was introduced into the dike safety evaluation.Based on the current relevant norms of dike safety evaluation,a hierarchical index system was constructed,which was composed of 5 first-level evaluation indexes,22 second-level evaluation indexes and 11 third-level evaluation indexes.Concerning the rating standards of the existing dike safety evaluation standards,based on the results of on-site quality inspection and safety review,the factors affecting dike safety were comprehensively considered through expert group decision-making.Each expert was given weight through the similarity of order relation to reflect the difference of different experts′ knowledge and experience.The traditional G1 method was improved,and the subjective weight of the index was calculated.The weight of the expert was calculated by entropy weight method to make the weight distribution of each index more scientific and reasonable.The corresponding three safety categories of dike safety were assigned to the corresponding scale interval and transformed into the corresponding safety cloud comments,and then the cloud comments of the third level evaluation index were determined by integrating expert opinions,and the floating cloud or integrated cloud computing model was used to fuse the cloud comments of different experts step by step.The total target cloud parameters of the dike safety state were obtained,and the corresponding cloud map was made,and the real safety state distribution of the dike was intuitively obtained.Based on this,the safety category was determined,and the development trend of the dike safety state was analyzed. Taking a dike on the left side of the Pearl River Channel as an example,the cloud evaluation of the third-level evaluation index was calculated using floating cloud,and the cloud parameters of the first-level index were obtained.The operation and management was rated as "unsafe" because of the great deficiency in the daily management and maintenance and safety monitoring of the dike,and the flood control capacity was rated as "unsafe" because the elevation of the dike was lower than the requirements of the design standards..Although the project quality was "basic safety",but the score is low,some "cloud droplets" fall into the "unsafe" scope.The main reason was that the dike took a long time to be completed and the construction standard was low.After many years of operation,the cross-section of the dike body,the clay content of the dike soil,the hidden danger of the dike body and the quality of slope protection have the problems of reduced safety,and the index value was on the low side.According to the cloud parameters of the first-level index and its corresponding combination optimization weight and overall goal of comprehensive cloud computing,the security state cloud map falls into the "basic security" range and was identified as the second-class dike,which was consistent with the conclusion of the traditional method of dike identification. The weight distribution of each index was optimized based on the scientific index system construction and combination weighting method,and the fuzziness and randomness of the influencing factors of dike safety were better combined by introducing cloud model theory.It is not only given a more accurate judgment of each state but also transforms the grade evaluation of dike safety into fuzzy and random comprehensive evaluation,compared with the traditional evaluation method.It can reflect the actual safety state of the dike more comprehensively,and provide a more scientific and reasonable basis for dike safety evaluation and strengthening management.
2021, 19(6):1227-1237.
Abstract:
Creep-type landslides generally have three stages from deformation to failure such as initial deformation,uniform deformation and accelerated deformation.According to the characteristics of deformation stages,a variety of landslide warning methods,based on thresholds such as cumulative displacement,deformation rate,and acceleration being proposed.In recent years,data mining technique has been applied to landslide warning.However,related researches have neglected the mining of the spatial deformation characteristics of multiple measuring points and the evolution laws of multivariable for landslides.Therefore,the data mining technique was applied to propose a landslide warning method based on the threshold of local outlier factors of multivariate monitoring time series.The proposed method can provide a reference for the judgment of the creep-type slope stages and the early warning of landslides. The dynamic time warping method (DTW) was used to calculate the distances among the deformation time series of multiple measuring points of the slope,and the Huygens theorem-based ward standard was employed to determine the clusters of the deformation measuring points.The similarities of the deformation laws of multiple measuring points were identified,and the spatiotemporal deformation evolution law of the slope was analyzed.Considering the multi-variables such as the main influencing factors and the multiple deformation measuring points,the local outlier factors (LOF) of the multivariable time series were calculated,and the abnormality existing in the multivariable change processes was analyzed.Based on the statistical methods,the early warning thresholds of LOFs under different confidence levels were determined,to divide the initial,uniform,and accelerated deformation stages of the landslide.Examples of Wolongsi and Xintan landslides were used to verify the effectiveness of the proposed method,and then applied to the creep-type landslide early warning of a canal slope. Two days before the landslide is the critical point of the accelerated deformation stage of the Wolongsi landslide.The LOF values of the cumulative displacement and the deformation rate of the deformation of the measuring points exceeded the thresholds at 95% and 99% confidence levels before two days and one day of landslide.The Xintan landslide experienced four stages:initial deformation,uniform deformation,acceleration deformation,and sharp acceleration deformation.The landslide entered the accelerated deformation stage in July 1982 and occurred on June 12,1985.The time series of the two measuring points A3 and B3 have high similarities.During the uniform deformation stage,the LOF values of the cumulative displacement in each rainy season had a corresponding increase process.In May 1982,the LOF values of the cumulative displacement exceeded the 95% confidence threshold.The LOF values continued to increase,approached the threshold of 99% confidence in August,and the LOF values of the deformation rate began to be at a higher value.In July 1984,the LOF values of the deformation rate exceeded the 95% confidence threshold many times,and in May 1985,it rose sharply and exceeded the 99% confidence threshold.The LOF values can identify the accelerated deformation stage earlier.The canal section X+740～X+860 of a water transfer project had a deep excavation slope.Three variables such as the rainfall and the cumulative displacements of the two measuring points 805-3-m and 835-3-m were considered.The LOF values of multivariate fluctuate slightly during the initial deformation stage.After entering the stable development stage,the multivariate LOF values fluctuate slightly,much less than the threshold when the confidence level is 95%.This canal slope was in a relatively stable development stage. The DTW based similarity measurement method can better reflect the correlation between the displacement time series of slope deformation measurement points.The clustering of the time series of the deformation measuring points can reasonably divide the measuring points into clusters.These can reflect the spatial similarity and heterogeneity of the change laws of the slope deformation measurement points,and facilitate the identification of the shear characteristics of the slope deformation.The LOF values of the deformation process have significant abrupt changes in the initial and the accelerated deformation stages.The LOF threshold based statistical methods for early warning of landslide is determined to divide the deformation stage and its evolution process can overcome the limitation of human estimation.The LOF value is more sensitive to time than human judgment estimation.The proposed early warning method based on the multivariable LOF is highly reliable and can gain more time for taking-emergency measures.The multivariable LOF values among multi-measuring points and external factors have the higher self-adjustment ability and better robustness.The landslide warning based on the multivariable LOF value thresholds can avoid the misjudgment of the landslide caused by the fluctuation of the measured value of accidental factors.
Creep-type landslides generally have three stages from deformation to failure such as initial deformation,uniform deformation and accelerated deformation.According to the characteristics of deformation stages,a variety of landslide warning methods,based on thresholds such as cumulative displacement,deformation rate,and acceleration being proposed.In recent years,data mining technique has been applied to landslide warning.However,related researches have neglected the mining of the spatial deformation characteristics of multiple measuring points and the evolution laws of multivariable for landslides.Therefore,the data mining technique was applied to propose a landslide warning method based on the threshold of local outlier factors of multivariate monitoring time series.The proposed method can provide a reference for the judgment of the creep-type slope stages and the early warning of landslides. The dynamic time warping method (DTW) was used to calculate the distances among the deformation time series of multiple measuring points of the slope,and the Huygens theorem-based ward standard was employed to determine the clusters of the deformation measuring points.The similarities of the deformation laws of multiple measuring points were identified,and the spatiotemporal deformation evolution law of the slope was analyzed.Considering the multi-variables such as the main influencing factors and the multiple deformation measuring points,the local outlier factors (LOF) of the multivariable time series were calculated,and the abnormality existing in the multivariable change processes was analyzed.Based on the statistical methods,the early warning thresholds of LOFs under different confidence levels were determined,to divide the initial,uniform,and accelerated deformation stages of the landslide.Examples of Wolongsi and Xintan landslides were used to verify the effectiveness of the proposed method,and then applied to the creep-type landslide early warning of a canal slope. Two days before the landslide is the critical point of the accelerated deformation stage of the Wolongsi landslide.The LOF values of the cumulative displacement and the deformation rate of the deformation of the measuring points exceeded the thresholds at 95% and 99% confidence levels before two days and one day of landslide.The Xintan landslide experienced four stages:initial deformation,uniform deformation,acceleration deformation,and sharp acceleration deformation.The landslide entered the accelerated deformation stage in July 1982 and occurred on June 12,1985.The time series of the two measuring points A3 and B3 have high similarities.During the uniform deformation stage,the LOF values of the cumulative displacement in each rainy season had a corresponding increase process.In May 1982,the LOF values of the cumulative displacement exceeded the 95% confidence threshold.The LOF values continued to increase,approached the threshold of 99% confidence in August,and the LOF values of the deformation rate began to be at a higher value.In July 1984,the LOF values of the deformation rate exceeded the 95% confidence threshold many times,and in May 1985,it rose sharply and exceeded the 99% confidence threshold.The LOF values can identify the accelerated deformation stage earlier.The canal section X+740～X+860 of a water transfer project had a deep excavation slope.Three variables such as the rainfall and the cumulative displacements of the two measuring points 805-3-m and 835-3-m were considered.The LOF values of multivariate fluctuate slightly during the initial deformation stage.After entering the stable development stage,the multivariate LOF values fluctuate slightly,much less than the threshold when the confidence level is 95%.This canal slope was in a relatively stable development stage. The DTW based similarity measurement method can better reflect the correlation between the displacement time series of slope deformation measurement points.The clustering of the time series of the deformation measuring points can reasonably divide the measuring points into clusters.These can reflect the spatial similarity and heterogeneity of the change laws of the slope deformation measurement points,and facilitate the identification of the shear characteristics of the slope deformation.The LOF values of the deformation process have significant abrupt changes in the initial and the accelerated deformation stages.The LOF threshold based statistical methods for early warning of landslide is determined to divide the deformation stage and its evolution process can overcome the limitation of human estimation.The LOF value is more sensitive to time than human judgment estimation.The proposed early warning method based on the multivariable LOF is highly reliable and can gain more time for taking-emergency measures.The multivariable LOF values among multi-measuring points and external factors have the higher self-adjustment ability and better robustness.The landslide warning based on the multivariable LOF value thresholds can avoid the misjudgment of the landslide caused by the fluctuation of the measured value of accidental factors.
2021, 19(6):1238-1248.
Abstract:
Uneven distribution of water quantity in regional water network results in cut-off and difficulty in satisfying ecological water demand.Therefore,it is necessary to scientifically formulate a scheme to regulate regional water network.Regulating water quantity by operating gate dams is a critical way,but the selection of different numbers and scales of gate dams will have different effects on the efficiency and effect of regulation results.How to select the key dams ? that may have a greater influence on the regional water network under different objective conditions and realize the efficient regulation of the water quantity.[JP] A gate dam evaluation index system is established which includes 10 indices from the aspect of water quantity,water quality,water ecology,and gate dam management.Taking the regional water network of Fenghe-Yongding River in Langfang as the research object,the AHP-entropy weight method is used to determine the index weight.To select the key gate dams under multi-objective water quantity regulation,the influence ability of each gate dam on the regional water network quantity regulation is evaluated.Considering the gate dams need to adjust the opening to achieve the water regulation target,a hydrodynamic mathematical model is built,and the opening of each key gate dam is set at five grades of 0%,25%,50%,75%,and 100%,and combined into 25 groups of simulation working conditions.Based on the simulation calculation of each working condition,the opening degree of each key dam and the range of water level is determined under the objective of satisfying the regional ecological water demand and flood control safety,and the judgment of the priority of the dam operation by the gate dam evaluation index system is verified. The composite key index of Yongfeng and Dongzhangwu are the highest,and they are the key gate dams in the regional multi-objective water quantity regulation.The differences between the single key and the composite key index are obvious for some gate dams.In practical application,the operating dam can be selected according to the regulation target.The composite key index can play a good reference role in water quantity regulation under the condition of multi-objective.For operating requirements,the gate and dam whose objective corresponds to a higher key index can be selected more accurately,and the composite key index can be considered at the same time.The opening of two key gate dams is set and combined into 25 working conditions to calculate the hydrodynamic model.Only four of the 25 working conditions meet the requirements of regional water network ecological water demand and flood control safety,and the index of hydraulic connectivity capacity under these four working conditions is relatively high,which is between 0.837 and 0.839. In conclusion,Yongfeng and Dongzhangwu gate dams are the keys in the target area,and their critical water quantity and composite indices are the highest in the gate dam evaluation index system.When the opening degree of Yongfeng gate dam is 50% to 75%,the opening degree of Dongzhangwu gate dam is 75% to 100%,and the corresponding water level range is 11.30 to 11.95 m and 10.55 to 11.65 m,respectively.It can ensure that each river reach and wetland in the target area and may meet the demand of ecological water level and give consideration to flood control safety.The evaluation index system has a directivity effect on operating gate dams under multi-objective regulation of water.It can reflect the influence degree of gate dams in a single aspect or comprehensive aspect.This method is used to determine the scheduling priority of gate dams.It is of significance reference to reasonably reduce the number of gate dams and improve the efficiency of water regulation.
Uneven distribution of water quantity in regional water network results in cut-off and difficulty in satisfying ecological water demand.Therefore,it is necessary to scientifically formulate a scheme to regulate regional water network.Regulating water quantity by operating gate dams is a critical way,but the selection of different numbers and scales of gate dams will have different effects on the efficiency and effect of regulation results.How to select the key dams ? that may have a greater influence on the regional water network under different objective conditions and realize the efficient regulation of the water quantity.[JP] A gate dam evaluation index system is established which includes 10 indices from the aspect of water quantity,water quality,water ecology,and gate dam management.Taking the regional water network of Fenghe-Yongding River in Langfang as the research object,the AHP-entropy weight method is used to determine the index weight.To select the key gate dams under multi-objective water quantity regulation,the influence ability of each gate dam on the regional water network quantity regulation is evaluated.Considering the gate dams need to adjust the opening to achieve the water regulation target,a hydrodynamic mathematical model is built,and the opening of each key gate dam is set at five grades of 0%,25%,50%,75%,and 100%,and combined into 25 groups of simulation working conditions.Based on the simulation calculation of each working condition,the opening degree of each key dam and the range of water level is determined under the objective of satisfying the regional ecological water demand and flood control safety,and the judgment of the priority of the dam operation by the gate dam evaluation index system is verified. The composite key index of Yongfeng and Dongzhangwu are the highest,and they are the key gate dams in the regional multi-objective water quantity regulation.The differences between the single key and the composite key index are obvious for some gate dams.In practical application,the operating dam can be selected according to the regulation target.The composite key index can play a good reference role in water quantity regulation under the condition of multi-objective.For operating requirements,the gate and dam whose objective corresponds to a higher key index can be selected more accurately,and the composite key index can be considered at the same time.The opening of two key gate dams is set and combined into 25 working conditions to calculate the hydrodynamic model.Only four of the 25 working conditions meet the requirements of regional water network ecological water demand and flood control safety,and the index of hydraulic connectivity capacity under these four working conditions is relatively high,which is between 0.837 and 0.839. In conclusion,Yongfeng and Dongzhangwu gate dams are the keys in the target area,and their critical water quantity and composite indices are the highest in the gate dam evaluation index system.When the opening degree of Yongfeng gate dam is 50% to 75%,the opening degree of Dongzhangwu gate dam is 75% to 100%,and the corresponding water level range is 11.30 to 11.95 m and 10.55 to 11.65 m,respectively.It can ensure that each river reach and wetland in the target area and may meet the demand of ecological water level and give consideration to flood control safety.The evaluation index system has a directivity effect on operating gate dams under multi-objective regulation of water.It can reflect the influence degree of gate dams in a single aspect or comprehensive aspect.This method is used to determine the scheduling priority of gate dams.It is of significance reference to reasonably reduce the number of gate dams and improve the efficiency of water regulation.
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