December 12, 2014-China Academy of Telecommunication Research of MIIT has announced its analysis report of domestic mobile phone market of November 2014. In November 2014, the overall shipments of mobile phones reach...December 12, 2014-China Academy of Telecommunication Research of MIIT has announced its analysis report of domestic mobile phone market of November 2014. In November 2014, the overall shipments of mobile phones reached 44.543 million units in China. Among which 2G mobile phone shipments was of 5.742 million, 3G mobile phone was of 7.2 million and 31.601 million for 4G ones. 4G mobile phone shipments continued to increase rapidly, which was more than 4 times of 3G mobile phone shipments.展开更多
The in-orbit commissioning of ZY-1 02C satellite is proceeding smoothly. According to the relevant experts in this field, the imagery quality of the satellite has reached or nearly reached the level of international s...The in-orbit commissioning of ZY-1 02C satellite is proceeding smoothly. According to the relevant experts in this field, the imagery quality of the satellite has reached or nearly reached the level of international satellites of the same kind. ZY-1 02C satellite and ZY-3 satellite were successfully launched on December 22, 2011 and January 9, 2012 respectively. China Centre for Resources Satellite Data andApplication (CRSDA) was responsible for the building of a ground展开更多
On June 19,2020 the project“Development and application of package technology for manufacture of 5 kt/a of hydrogenation catalysts”,in the implementation of which the Resarch Institute of Petroleum Processing(RIPP)h...On June 19,2020 the project“Development and application of package technology for manufacture of 5 kt/a of hydrogenation catalysts”,in the implementation of which the Resarch Institute of Petroleum Processing(RIPP)has been taking part,had passed the apparaisal organized by the SINOPEC Science and Technology Division.This project has realized the integration,scale-up,and automation of hydrogenation catalyst production unit,while achieving low energy consumption and cleanness of hydrogenation catalyst production process,with its technology reaching an internationally advanced level.展开更多
[Objective]Implementation of the Ten-Year Fishing Ban policy may alter fish diversity and niche characteristics of dominant species in spawning grounds within the National Nature Reserve for Rare and Endemic Fish in t...[Objective]Implementation of the Ten-Year Fishing Ban policy may alter fish diversity and niche characteristics of dominant species in spawning grounds within the National Nature Reserve for Rare and Endemic Fish in the Upper Yangtze River.This study initiated continuous monitoring of natural spawning habitats from February 2022 to assess these ecological changes.[Methods]Environmental DNA(eDNA)metabarcoding was employed to analyze fish species composition,biodiversity patterns,and niche parameters of dominant species.Water sampling followed the CEN/TS 19461 standard across five monitoring transects(ZT1-ZT5).[Results]The eDNA analysis detected 45 species of fish belonging to 38 genera,13 families,and 3 orders were detected through environmental DNA(eDNA)in this survey,including 10 species endemic to the upper reaches of the Yangtze River,such as Procypris rabaudi and Myxocyprinus asiaticus.The fish community was mainly composed of bottom-dwelling,settling ovum-producing,omnivorous fish.The variation ranges of the Chao1 index,ACE index,Shannon index,and Simpson index are 736~996,719~965,1.58~3.23,and 0.83~0.99,respectively,indicating that fish species in spawning sites are abundant and community distribution uniformity is high.All indexes are highest at ZT1 monitoring points.Cluster analysis showed that,at a certain similarity level,fish community types in spawning sites could be basically divided into two groups:ZT1,ZT3,and ZT5 clustered together,and ZT2 and ZT4 clustered together,indicating similar fish community habitats.There are 9 dominant fish species in typical deep pool habitats in the reserve,with niche widths(Bi)ranging from 1.13 to 3.87.The dominant fish species are broad and medium niche fish,such as Cyprinus carpio and Hemiculter tchangi,with the niche overlap index(Oik)of some dominant fish species reaching more than 0.95.This indicates fierce competition for resources among the fish in this spawning ground.[Conclusion]The Zhutuo spawning ground demonstrates high species richness with homogeneous community structure and intense resource competition.This study establishes an eDNA-based monitoring framework that enhances conventional survey method,providing critical baseline data for adaptive management under the fishing moratorium regime.展开更多
The global issue of climate change presents young entrepreneurs with opportunities to explore new business models.FACED with the severe challenges presented by global climate change,pursuing a green lifestyle is a way...The global issue of climate change presents young entrepreneurs with opportunities to explore new business models.FACED with the severe challenges presented by global climate change,pursuing a green lifestyle is a way to achieve sustainable development.Many countries are exploring ways to reach a balance between economic development and environmental protection.展开更多
Collaborative changes in the hydro-sediment regime and erosional base level are vital factors that influence the evolution of wandering rivers.In the wandering Xiaobeiganliu reach of the Middle Yellow River(MYR),the r...Collaborative changes in the hydro-sediment regime and erosional base level are vital factors that influence the evolution of wandering rivers.In the wandering Xiaobeiganliu reach of the Middle Yellow River(MYR),the rapidly decreasing sediment discharge and lowering base level,i.e.,the Tongguan elevation,have resulted in new features of thalweg migration in river morphology.In this work,on the basis of topographic measurements of the reach from 2003–2021,the thalweg migration distance and intensity were calculated at both the section scale and reach scale.The results revealed that the annual sediment discharge decreased by 72%from 1986–2002,and the reach exhibited sustained scouring from deposition,leading to the Tongguan elevation decreasing by 1.69 m compared with that in 2002.Accordingly,the distance and intensity of thalweg migration have been reduced to varying degrees in both section and reach scales.The maximum section-scale thalweg migration distance was reduced by 11%,whereas the average thalweg migration distance and intensity at the reach scale decreased by 14%and 43%,respectively.During this sustained scouring period,the fluvial erosion intensity at the reach scale increased as the sediment discharge decreased.However,because the base level remained high,riverbed undercutting was deeply limited,which exacerbated lateral erosion of the bank and floodplain,enhancing thalweg migration.Flow-sediment regulation and training can be coupled to increase undercutting efficiency in the main channel and to protect banks from lateral erosion in river reach management.展开更多
The backwater effect caused by tributary inflow can significantly elevate the water level profile upstream of a confluence point.However,the influence of mainstream and confluence discharges on the backwater effect in...The backwater effect caused by tributary inflow can significantly elevate the water level profile upstream of a confluence point.However,the influence of mainstream and confluence discharges on the backwater effect in a river reach remains unclear.In this study,various hydrological data collected from the Jingjiang Reach of the Yangtze River in China were statistically analyzed to determine the backwater degree and range with three representative mainstream discharges.The results indicated that the backwater degree increased with mainstream discharge,and a positive relationship was observed between the runoff ratio and backwater degree at specific representative mainstream discharges.Following the operation of the Three Gorges Project,the backwater effect in the Jingjiang Reach diminished.For instance,mean backwater degrees for low,moderate,and high mainstream discharges were recorded as 0.83 m,1.61 m,and 2.41 m during the period from 1990 to 2002,whereas these values decreased to 0.30 m,0.95 m,and 2.08 m from 2009 to 2020.The backwater range extended upstream as mainstream discharge increased from 7000 m3/s to 30000 m3/s.Moreover,a random forest-based machine learning model was used to quantify the backwater effect with varying mainstream and confluence discharges,accounting for the impacts of mainstream discharge,confluence discharge,and channel degradation in the Jingjiang Reach.At the Jianli Hydrological Station,a decrease in mainstream discharge during flood seasons resulted in a 7%–15%increase in monthly mean backwater degree,while an increase in mainstream discharge during dry seasons led to a 1%–15%decrease in monthly mean backwater degree.Furthermore,increasing confluence discharge from Dongting Lake during June to July and September to November resulted in an 11%–42%increase in monthly mean backwater degree.Continuous channel degradation in the Jingjiang Reach contributed to a 6%–19%decrease in monthly mean backwater degree.Under the influence of these factors,the monthly mean backwater degree in 2017 varied from a decrease of 53%to an increase of 37%compared to corresponding values in 1991.展开更多
This paper introduces a novel chattering-free terminal sliding mode control(SMC)strategy to address chaotic behavior in permanent magnet synchronous generators(PMSG)for offshore wind turbine systems.By integrating an ...This paper introduces a novel chattering-free terminal sliding mode control(SMC)strategy to address chaotic behavior in permanent magnet synchronous generators(PMSG)for offshore wind turbine systems.By integrating an adaptive exponential reaching law with a continuous barrier function,the proposed approach eliminates chattering and ensures robust performance under model uncertainties.The methodology combines adaptive SMC with dynamic switching to estimate and compensates for unknown uncertainties,providing smooth and stable control.Finally,the performance and effectiveness of the proposed approach are compared with those of a previous study.展开更多
This paper selects sampling sections for the mainstream and tributaries of the middle and lower reaches of the Yellow River,collects river water and sediment samples during the flood season for pollen analysis,and use...This paper selects sampling sections for the mainstream and tributaries of the middle and lower reaches of the Yellow River,collects river water and sediment samples during the flood season for pollen analysis,and uses methods such as Geodetector to explore the distribution characteristics and influencing factors of pollen.The results show significant variations in vegetation composition across different watersheds,leading to notable differences in both the percentage and concentration of pollen types.Pollen concentration in river water is generally higher in the mainstream compared to tributaries,while sediment pollen percentage and concentration are typically lower in the mainstream than in tributaries.The concentration of suspended solids is the most significant factor affecting pollen concentration in the Yellow River,with this effect being particularly prominent outside the Shanxi-Shaanxi Gorge.Abundant coarse sand and rapid flow velocities are likely responsible for the high suspended solids concentration and lower pollen concentration observed in the mainstream of the Shanxi-Shaanxi Gorge.In sediments,clay content is the primary factor influencing pollen concentration,and its interaction with silt and flow velocity has a more prominent influence on pollen concentration.At the Yellow River section below the Shanxi-Shaanxi Gorge,sediment pollen and clay concentrations significantly increase.The changes in pollen concentration in the river water before and after the reservoir are consistent with the suspended solids concentration,while the changes in sediment pollen concentration are consistent with the clay content.Notably,pollen concentrations in sediments decrease more significantly after passing through a reservoir compared to changes observed in river water samples.Overall,there is a strong correlation between river pollen and topsoil pollen,which can provide a reliable reflection of the broader vegetation landscape of the watershed.The findings can provide support for paleoenvironmental reconstruction using pollen from alluvial sediments or lakes with river inflows.展开更多
Changes in river cross-section morphology have decisive influences on the flood discharge and sand transport capacity of rivers;thus,these changes strongly reflect the vitality of a river.In this paper,based on the ri...Changes in river cross-section morphology have decisive influences on the flood discharge and sand transport capacity of rivers;thus,these changes strongly reflect the vitality of a river.In this paper,based on the river cross-section and water and sediment data of two different periods(1974−1987 and 2007−2021),the trend analysis,change-point analysis and sediment rating curve method were used to analyze the change process of river cross-section morphology and its response to streamflow and sediment changes in the main river stream of the Yellow River at the Longmen hydrological station.From 1974 to 1987(except in 1977),the riverbed experi-enced siltation,and the riverbed elevation rose.Conversely,from 2007 to 2021,the riverbed experienced scouring,and the riverbed el-evation gradually decreased.The cross-section shape changed from rectangular to U-shaped(deeper on the right side)at the Longmen cross-section.The changes in streamflow and sediment processes significantly impacted the evolution of river cross-section.Stream-flow(P<0.05),sediment discharge(P<0.01),and the sediment load coefficients(P<0.01)decreased significantly.The relationship between the water depth and sediment load coefficients followed a power function.The decreasing trend in sediment discharge was sig-nificantly stronger than that in streamflow.Suspended sediment particles tended to become finer.The sediment rating curve indicates that the sediment supply from upstream decreased while the erosive power in the river channel increased,leading to a gradual decline in riverbed elevation at the Longmen cross-section from 2007 to 2021.These findings help us better understand the impacts of ecological restoration on changes in river streamflow and sediment during river evolution.展开更多
Drought is an important disaster factor disturbing the stability of the ecosystem in the middle reaches of the Yellow River(YRM).In this study,the spatiotemporal distribution of drought in the YRM from 2000 to 2021 wa...Drought is an important disaster factor disturbing the stability of the ecosystem in the middle reaches of the Yellow River(YRM).In this study,the spatiotemporal distribution of drought in the YRM from 2000 to 2021 was quantitatively investigated by constructing the TVPDI(Temperature-VegetationPrecipitation Dryness Index),and its driving mechanism was explored.The results show that:(1)a significant decreasing trend was observed in the regional annual TVPDI of the YRM,while the autumn TVPDI index showed an increasing trend during 2000-2021.(2)Plants are more susceptible to drought during the growing season.(3)Drought in YRM showed significant spatial heterogeneity,and the high gully area in the Loess Plateau and the earth-rocky mountain areas were less affected by drought than other regions.(4)The Structural Equation Model(SEM)indicated that regional soil moisture and vegetation coverage have a direct influence on regional TVPDI variation.This study has explored the regional differences of drought in different seasons and landforms in the YRM,providing a basis for carrying out targeted seasonal ecological management and refining regional environmental governance,as well as a reference for formulating differentiated ecological restoration and water resource allocation strategies according to local conditions.展开更多
Studying the causes of summer(June–July–August)precipitation anomalies in the middle and lower reaches of the Yangtze River(MLYR)and accurately predicting rainy season precipitation are important to society and the ...Studying the causes of summer(June–July–August)precipitation anomalies in the middle and lower reaches of the Yangtze River(MLYR)and accurately predicting rainy season precipitation are important to society and the economy.In recent years,the sea surface temperature(SST)trend factor has been used to construct regression models for summer precipitation.In this study,through correlation analysis,winter SST anomaly predictors and the winter Central Pacific SST trend predictor(CPT)are identified as closely related to the following MLYR summer precipitation(YRSP).CPT can influence YRSP by inducing anomalous circulations over the North Pacific,guiding warm and moist air northward,and inhibiting the development of the anomalous anticyclone over the Northwest Pacific.This has improved the predictive skill of the seasonal regression model for YRSP.After incorporating the CPT,the correlation coefficient of the YRSP regression model improved by 40%,increasing from 0.45 to 0.63,and the root mean squared error decreased by 22%,from 1.15 to 0.90.展开更多
The energy consumption of copper smelting in china reaches the lowest the world.According to information collected from China Nonferrous Metal Industry Association,in 2010,Dongying Fangyuan Non-ferrous Metals
文摘December 12, 2014-China Academy of Telecommunication Research of MIIT has announced its analysis report of domestic mobile phone market of November 2014. In November 2014, the overall shipments of mobile phones reached 44.543 million units in China. Among which 2G mobile phone shipments was of 5.742 million, 3G mobile phone was of 7.2 million and 31.601 million for 4G ones. 4G mobile phone shipments continued to increase rapidly, which was more than 4 times of 3G mobile phone shipments.
文摘The in-orbit commissioning of ZY-1 02C satellite is proceeding smoothly. According to the relevant experts in this field, the imagery quality of the satellite has reached or nearly reached the level of international satellites of the same kind. ZY-1 02C satellite and ZY-3 satellite were successfully launched on December 22, 2011 and January 9, 2012 respectively. China Centre for Resources Satellite Data andApplication (CRSDA) was responsible for the building of a ground
文摘On June 19,2020 the project“Development and application of package technology for manufacture of 5 kt/a of hydrogenation catalysts”,in the implementation of which the Resarch Institute of Petroleum Processing(RIPP)has been taking part,had passed the apparaisal organized by the SINOPEC Science and Technology Division.This project has realized the integration,scale-up,and automation of hydrogenation catalyst production unit,while achieving low energy consumption and cleanness of hydrogenation catalyst production process,with its technology reaching an internationally advanced level.
文摘[Objective]Implementation of the Ten-Year Fishing Ban policy may alter fish diversity and niche characteristics of dominant species in spawning grounds within the National Nature Reserve for Rare and Endemic Fish in the Upper Yangtze River.This study initiated continuous monitoring of natural spawning habitats from February 2022 to assess these ecological changes.[Methods]Environmental DNA(eDNA)metabarcoding was employed to analyze fish species composition,biodiversity patterns,and niche parameters of dominant species.Water sampling followed the CEN/TS 19461 standard across five monitoring transects(ZT1-ZT5).[Results]The eDNA analysis detected 45 species of fish belonging to 38 genera,13 families,and 3 orders were detected through environmental DNA(eDNA)in this survey,including 10 species endemic to the upper reaches of the Yangtze River,such as Procypris rabaudi and Myxocyprinus asiaticus.The fish community was mainly composed of bottom-dwelling,settling ovum-producing,omnivorous fish.The variation ranges of the Chao1 index,ACE index,Shannon index,and Simpson index are 736~996,719~965,1.58~3.23,and 0.83~0.99,respectively,indicating that fish species in spawning sites are abundant and community distribution uniformity is high.All indexes are highest at ZT1 monitoring points.Cluster analysis showed that,at a certain similarity level,fish community types in spawning sites could be basically divided into two groups:ZT1,ZT3,and ZT5 clustered together,and ZT2 and ZT4 clustered together,indicating similar fish community habitats.There are 9 dominant fish species in typical deep pool habitats in the reserve,with niche widths(Bi)ranging from 1.13 to 3.87.The dominant fish species are broad and medium niche fish,such as Cyprinus carpio and Hemiculter tchangi,with the niche overlap index(Oik)of some dominant fish species reaching more than 0.95.This indicates fierce competition for resources among the fish in this spawning ground.[Conclusion]The Zhutuo spawning ground demonstrates high species richness with homogeneous community structure and intense resource competition.This study establishes an eDNA-based monitoring framework that enhances conventional survey method,providing critical baseline data for adaptive management under the fishing moratorium regime.
文摘The global issue of climate change presents young entrepreneurs with opportunities to explore new business models.FACED with the severe challenges presented by global climate change,pursuing a green lifestyle is a way to achieve sustainable development.Many countries are exploring ways to reach a balance between economic development and environmental protection.
基金National Key R&D Program of China,No.2023YFC3206205National Natural Science Foundation of China,No.U22A20237Independent Research Project of Yellow River Engineering Consulting Co.,Ltd.,No.2025KY001。
文摘Collaborative changes in the hydro-sediment regime and erosional base level are vital factors that influence the evolution of wandering rivers.In the wandering Xiaobeiganliu reach of the Middle Yellow River(MYR),the rapidly decreasing sediment discharge and lowering base level,i.e.,the Tongguan elevation,have resulted in new features of thalweg migration in river morphology.In this work,on the basis of topographic measurements of the reach from 2003–2021,the thalweg migration distance and intensity were calculated at both the section scale and reach scale.The results revealed that the annual sediment discharge decreased by 72%from 1986–2002,and the reach exhibited sustained scouring from deposition,leading to the Tongguan elevation decreasing by 1.69 m compared with that in 2002.Accordingly,the distance and intensity of thalweg migration have been reduced to varying degrees in both section and reach scales.The maximum section-scale thalweg migration distance was reduced by 11%,whereas the average thalweg migration distance and intensity at the reach scale decreased by 14%and 43%,respectively.During this sustained scouring period,the fluvial erosion intensity at the reach scale increased as the sediment discharge decreased.However,because the base level remained high,riverbed undercutting was deeply limited,which exacerbated lateral erosion of the bank and floodplain,enhancing thalweg migration.Flow-sediment regulation and training can be coupled to increase undercutting efficiency in the main channel and to protect banks from lateral erosion in river reach management.
基金supported by the National Key Research and Development Program of China(Grant No.2023YFC3209504)the National Natural Science Foundation of China(Grants No.U2040215 and 52479075)the Natural Science Foundation of Hubei Province(Grant No.2021CFA029).
文摘The backwater effect caused by tributary inflow can significantly elevate the water level profile upstream of a confluence point.However,the influence of mainstream and confluence discharges on the backwater effect in a river reach remains unclear.In this study,various hydrological data collected from the Jingjiang Reach of the Yangtze River in China were statistically analyzed to determine the backwater degree and range with three representative mainstream discharges.The results indicated that the backwater degree increased with mainstream discharge,and a positive relationship was observed between the runoff ratio and backwater degree at specific representative mainstream discharges.Following the operation of the Three Gorges Project,the backwater effect in the Jingjiang Reach diminished.For instance,mean backwater degrees for low,moderate,and high mainstream discharges were recorded as 0.83 m,1.61 m,and 2.41 m during the period from 1990 to 2002,whereas these values decreased to 0.30 m,0.95 m,and 2.08 m from 2009 to 2020.The backwater range extended upstream as mainstream discharge increased from 7000 m3/s to 30000 m3/s.Moreover,a random forest-based machine learning model was used to quantify the backwater effect with varying mainstream and confluence discharges,accounting for the impacts of mainstream discharge,confluence discharge,and channel degradation in the Jingjiang Reach.At the Jianli Hydrological Station,a decrease in mainstream discharge during flood seasons resulted in a 7%–15%increase in monthly mean backwater degree,while an increase in mainstream discharge during dry seasons led to a 1%–15%decrease in monthly mean backwater degree.Furthermore,increasing confluence discharge from Dongting Lake during June to July and September to November resulted in an 11%–42%increase in monthly mean backwater degree.Continuous channel degradation in the Jingjiang Reach contributed to a 6%–19%decrease in monthly mean backwater degree.Under the influence of these factors,the monthly mean backwater degree in 2017 varied from a decrease of 53%to an increase of 37%compared to corresponding values in 1991.
文摘This paper introduces a novel chattering-free terminal sliding mode control(SMC)strategy to address chaotic behavior in permanent magnet synchronous generators(PMSG)for offshore wind turbine systems.By integrating an adaptive exponential reaching law with a continuous barrier function,the proposed approach eliminates chattering and ensures robust performance under model uncertainties.The methodology combines adaptive SMC with dynamic switching to estimate and compensates for unknown uncertainties,providing smooth and stable control.Finally,the performance and effectiveness of the proposed approach are compared with those of a previous study.
基金National Natural Science Foundation of China,No.41907382China Postdoctoral Science Foundation,No.2019M652520Henan Postdoctoral Science Foundation,No.201902025。
文摘This paper selects sampling sections for the mainstream and tributaries of the middle and lower reaches of the Yellow River,collects river water and sediment samples during the flood season for pollen analysis,and uses methods such as Geodetector to explore the distribution characteristics and influencing factors of pollen.The results show significant variations in vegetation composition across different watersheds,leading to notable differences in both the percentage and concentration of pollen types.Pollen concentration in river water is generally higher in the mainstream compared to tributaries,while sediment pollen percentage and concentration are typically lower in the mainstream than in tributaries.The concentration of suspended solids is the most significant factor affecting pollen concentration in the Yellow River,with this effect being particularly prominent outside the Shanxi-Shaanxi Gorge.Abundant coarse sand and rapid flow velocities are likely responsible for the high suspended solids concentration and lower pollen concentration observed in the mainstream of the Shanxi-Shaanxi Gorge.In sediments,clay content is the primary factor influencing pollen concentration,and its interaction with silt and flow velocity has a more prominent influence on pollen concentration.At the Yellow River section below the Shanxi-Shaanxi Gorge,sediment pollen and clay concentrations significantly increase.The changes in pollen concentration in the river water before and after the reservoir are consistent with the suspended solids concentration,while the changes in sediment pollen concentration are consistent with the clay content.Notably,pollen concentrations in sediments decrease more significantly after passing through a reservoir compared to changes observed in river water samples.Overall,there is a strong correlation between river pollen and topsoil pollen,which can provide a reliable reflection of the broader vegetation landscape of the watershed.The findings can provide support for paleoenvironmental reconstruction using pollen from alluvial sediments or lakes with river inflows.
基金Under the auspices of the National Natural Science Foundation of China(No.42277354,U2243211)Fundamental Research Funds for the Hebei University of Water Resources and Electric Engineering(No.SYKY2113)Science Research Project of Hebei Education Department(No.QN2025293)。
文摘Changes in river cross-section morphology have decisive influences on the flood discharge and sand transport capacity of rivers;thus,these changes strongly reflect the vitality of a river.In this paper,based on the river cross-section and water and sediment data of two different periods(1974−1987 and 2007−2021),the trend analysis,change-point analysis and sediment rating curve method were used to analyze the change process of river cross-section morphology and its response to streamflow and sediment changes in the main river stream of the Yellow River at the Longmen hydrological station.From 1974 to 1987(except in 1977),the riverbed experi-enced siltation,and the riverbed elevation rose.Conversely,from 2007 to 2021,the riverbed experienced scouring,and the riverbed el-evation gradually decreased.The cross-section shape changed from rectangular to U-shaped(deeper on the right side)at the Longmen cross-section.The changes in streamflow and sediment processes significantly impacted the evolution of river cross-section.Stream-flow(P<0.05),sediment discharge(P<0.01),and the sediment load coefficients(P<0.01)decreased significantly.The relationship between the water depth and sediment load coefficients followed a power function.The decreasing trend in sediment discharge was sig-nificantly stronger than that in streamflow.Suspended sediment particles tended to become finer.The sediment rating curve indicates that the sediment supply from upstream decreased while the erosive power in the river channel increased,leading to a gradual decline in riverbed elevation at the Longmen cross-section from 2007 to 2021.These findings help us better understand the impacts of ecological restoration on changes in river streamflow and sediment during river evolution.
基金supported by the National Natural Science Foundation of China(Grant No.41601317)"14th Five Year Plan"For Education Sciences Planning of Shanxi Province(Grant No.SZH-230067)Ideological and Political Courses at Shanxi Normal University(2023KCSZ-15)。
文摘Drought is an important disaster factor disturbing the stability of the ecosystem in the middle reaches of the Yellow River(YRM).In this study,the spatiotemporal distribution of drought in the YRM from 2000 to 2021 was quantitatively investigated by constructing the TVPDI(Temperature-VegetationPrecipitation Dryness Index),and its driving mechanism was explored.The results show that:(1)a significant decreasing trend was observed in the regional annual TVPDI of the YRM,while the autumn TVPDI index showed an increasing trend during 2000-2021.(2)Plants are more susceptible to drought during the growing season.(3)Drought in YRM showed significant spatial heterogeneity,and the high gully area in the Loess Plateau and the earth-rocky mountain areas were less affected by drought than other regions.(4)The Structural Equation Model(SEM)indicated that regional soil moisture and vegetation coverage have a direct influence on regional TVPDI variation.This study has explored the regional differences of drought in different seasons and landforms in the YRM,providing a basis for carrying out targeted seasonal ecological management and refining regional environmental governance,as well as a reference for formulating differentiated ecological restoration and water resource allocation strategies according to local conditions.
基金Guangdong Major Project of Basic and Applied Basic Research(2020B0301030004)National Natural Science Foundation of China(42175061)。
文摘Studying the causes of summer(June–July–August)precipitation anomalies in the middle and lower reaches of the Yangtze River(MLYR)and accurately predicting rainy season precipitation are important to society and the economy.In recent years,the sea surface temperature(SST)trend factor has been used to construct regression models for summer precipitation.In this study,through correlation analysis,winter SST anomaly predictors and the winter Central Pacific SST trend predictor(CPT)are identified as closely related to the following MLYR summer precipitation(YRSP).CPT can influence YRSP by inducing anomalous circulations over the North Pacific,guiding warm and moist air northward,and inhibiting the development of the anomalous anticyclone over the Northwest Pacific.This has improved the predictive skill of the seasonal regression model for YRSP.After incorporating the CPT,the correlation coefficient of the YRSP regression model improved by 40%,increasing from 0.45 to 0.63,and the root mean squared error decreased by 22%,from 1.15 to 0.90.
文摘The energy consumption of copper smelting in china reaches the lowest the world.According to information collected from China Nonferrous Metal Industry Association,in 2010,Dongying Fangyuan Non-ferrous Metals
