With the large-scale deployment of satellite constellations such as Starlink and the rapid advancement of technologies including artificial intelligence (AI) and non-terrestrial networks (NTNs), the integration of hig...With the large-scale deployment of satellite constellations such as Starlink and the rapid advancement of technologies including artificial intelligence (AI) and non-terrestrial networks (NTNs), the integration of high, medium, and low Earth orbit satellite networks with terrestrial networks has become a critical direction for future communication technologies. The objective is to develop a space-terrestrial integrated 6G network that ensures ubiquitous connectivity and seamless services, facilitating intelligent interconnection and collaborative symbiosis among humans, machines, and objects. This integration has become a central focus of global technological innovation.展开更多
Branch angles are an important plant morphological trait affecting light interception within forest canopies.However,studies on branch angles have been limited due to the time-consuming nature of manual measurements u...Branch angles are an important plant morphological trait affecting light interception within forest canopies.However,studies on branch angles have been limited due to the time-consuming nature of manual measurements using a protractor.Terrestrial laser scanning(TLS),however,provides new opportunities to measure branch angles more efficiently.Despite this potential,studies validating branch angle measurements from TLS have been limited.Here,our aim is to evaluate both manual and automatic branch angle measurements of European beech from TLS data using traditional field-measurements with a protractor as a reference.We evaluated the accuracy of branch angle measurements based on four automated algorithms(aRchiQSM,TreeQSM,Laplacian,SemanticLaplacian)from TLS data.Additionally,we assessed different ways of manual branch angle measurements in the field.Our study was based on a dataset comprising 124 branch angles measured from six European beech in a European deciduous forest.Our results show that manual branch angle measurements from TLS data are in high agreement with the reference(root-mean-squared error,RMSE:[3.57°-4.18°],concordance correlation coefficient,CCC:[0.950.97])across different branch length positions.Automated algorithms also are in high agreement with the reference although RMSE is approximately twice as large compared to manual branch angle measurements from TLS(RMSE:[9.29°-10.55°],CCC:[0.830.86])with manual leaf points removal.When applying the automatic wood-leaf separation algorithm,the performance of the four methods declined significantly,with only approximately 20 branch angles successfully identified.Moreover,it is important to note that there is no influence of the measurement position(branch surface versus center)for branch angle measurements.However,for curved branches,the selection of branch measurement length significantly impacts the branch angle measurement.This study provides a comprehensive understanding of branch angle measurements in forests.We show that automated measurement methods based on TLS data of branch angles are a valuable tool to quantify branch angles at larger scales.展开更多
1.Introduction As a key development of the next-generation spatial information infrastructure,1the Satellite-Terrestrial Integrated Network(STIN)has become a strategic priority actively pursued by major spacefaring na...1.Introduction As a key development of the next-generation spatial information infrastructure,1the Satellite-Terrestrial Integrated Network(STIN)has become a strategic priority actively pursued by major spacefaring nations and regions,including the United States,Europe,China,and Russia.Specifically,Space X’s Starlink project has deployed over 6750 satellites,2while One Web has completed its initial phase of satellite constellation deployment with more than 600 satellites.展开更多
Climate change and anthropogenic activities have driven significant terrestrial water storage changes(TWSC)in the Three Rivers Source Region(TRSR),exerting profound impacts on freshwater availability across China and ...Climate change and anthropogenic activities have driven significant terrestrial water storage changes(TWSC)in the Three Rivers Source Region(TRSR),exerting profound impacts on freshwater availability across China and broader Asia.However,long-term TWSC characterization remains challenging due to limited observational data in this alpine region.Here,we integrate GRACE observations(2002-2020),ERA5-Land reanalysis,and GLDAS data to reconstruct TWSC using two methods:(1)the water balance method(PER)and(2)the component summation method(SS),applied to three input datasets(ERA5-Land,GLDAS,and their average,GLER).Comparative analysis reveals that the SS method applied to GL-ER yields the highest consistency with GRACE-derived TWSC.Using this optimal approach,we extend the analysis to 1951~2020,uncovering spatiotemporal TWSC patterns.Although annual TWSC trends appear negligible due to strong seasonality,we introduce the intra-year TWSC fluctuation(TWSCF)index to quantify cumulative variability.A significant(p<0.05)transition occurred in 1980,with TWSCF shifting from a declining trend(-0.39 mm/yr)to an increasing trend(0.56 mm/yr),primarily driven by soil moisture changes.However,Hurst exponent analysis suggests this upward trend may not persist.Drought and vegetation assessments indicate concurrent wetting and greening in the TRSR.TWSC correlates strongly with meteorological drought,acting as a reliable drought indicator while its linkage with vegetation dynamics suggests a potential contribution to greening.Our findings provide a robust framework for understanding long-term TWSC evolution and its hydrological-ecological interactions under climate change.展开更多
The rhenium-osmium(Re-Os)isotope system is a powerful tool for dating organic-rich sedimentary rocks,yet the mechanisms of Re and Os uptake and their fractionation in different types of organic matter remain poorly un...The rhenium-osmium(Re-Os)isotope system is a powerful tool for dating organic-rich sedimentary rocks,yet the mechanisms of Re and Os uptake and their fractionation in different types of organic matter remain poorly understood.Here,we investigate the role of terrestrial organic matter(e.g.,wood of the species Taxodium distichum and charcoal generated from the same species in the laboratory)in Re and Os enrichment and isotope fractionation through laboratory experiments.The results show that charcoal has a significantly higher capacity to uptake both Re(68-77 times greater)and Os(1.7-2.2 times higher)compared to wood,with charcoal preferentially accumulating Re over Os,leading to higher^(187)Re/^(188)Os ratios.These findings highlight the important contribution of terrestrial organic matter,particularly charcoal,to Re and Os concentrations and isotope fractionation in shales,and the importance of organic matter type for chelating Re and Os as previously discussed.Furthermore,we discuss the potential of using Re to track organic carbon weathering,noting that the coupled release of Re and organic carbon during weathering provides new insights into carbon cycling processes.展开更多
In this study,terrestrial laser scanning(TLS)is used to collect building data after the M_(s) 7.0 magnitude earthquake in Lushan,Sichuan,China in 2013 for analysis and research.The analysis focuses on extracting the t...In this study,terrestrial laser scanning(TLS)is used to collect building data after the M_(s) 7.0 magnitude earthquake in Lushan,Sichuan,China in 2013 for analysis and research.The analysis focuses on extracting the tilt and deformation of masonry buildings that are difficult to identify through visual inspection in basically intact,slightly damaged and moderately damaged masonry buildings,to solve the problem of ambiguous identification of damage.A quantitative analysis of the determination indexes of the degree of earthquake damage was carried out,and the numerical characteristics parameters such as the curvature of the wall point cloud proximity,angle,contour of the fitted plane of the point cloud,verticality(flatness)of the wall,standard deviation of the profile and angle of the profile were established to determine the degree of earthquake damage to buildings based on LiDAR data.The development of quantitative determination indexes for the degree of earthquake damage of buildings in this study has important application value for LiDAR data in the identification and extraction of earthquake damage information and damage level determination.展开更多
In this paper,we propose a joint power and frequency allocation algorithm considering interference protection in the integrated satellite and terrestrial network(ISTN).We efficiently utilize spectrum resources by allo...In this paper,we propose a joint power and frequency allocation algorithm considering interference protection in the integrated satellite and terrestrial network(ISTN).We efficiently utilize spectrum resources by allowing user equipment(UE)of terrestrial networks to share frequencies with satellite networks.In order to protect the satellite terminal(ST),the base station(BS)needs to control the transmit power and frequency resources of the UE.The optimization problem involves maximizing the achievable throughput while satisfying the interference protection constraints of the ST and the quality of service(QoS)of the UE.However,this problem is highly nonconvex,and we decompose it into power allocation and frequency resource scheduling subproblems.In the power allocation subproblem,we propose a power allocation algorithm based on interference probability(PAIP)to address channel uncertainty.We obtain the suboptimal power allocation solution through iterative optimization.In the frequency resource scheduling subproblem,we develop a heuristic algorithm to handle the non-convexity of the problem.The simulation results show that the combination of power allocation and frequency resource scheduling algorithms can improve spectrum utilization.展开更多
The present study was conducted to examine the trophic transfer of potentially toxic elements(PTEs)in a closed arsenic mine.Eight PTEs in a soil-plant-leaf litter-earthworm-top predators(free-range local chicken and w...The present study was conducted to examine the trophic transfer of potentially toxic elements(PTEs)in a closed arsenic mine.Eight PTEs in a soil-plant-leaf litter-earthworm-top predators(free-range local chicken and wild passerine bird)system were analyzed for nitrogen and carbon stable isotopes,PTE concentrations,bioaccumulation factors(BAFs),and transfer factors(TFs).The PTE concentrations in soils from mining areas were generally higher than a adjacent controlled area,with As and Cd in soils showing the prominent compared to other six PTEs,as seen for the indices of geo-accumulation index(I_(geo)),pollution index(PI)and potential ecological risk index(RI).The relatively high BAF and TF values suggested a distinct biotransfer of PTEs along the soil-plant-leaf litter-earthworm system.BAFs were mostly<1 except in earthworms,indicating that earthworms had a strong capacity to take up these metals.The TFs varied both among PTEs and organism’s species,e.g.,the transfer capacities of As in Pteris vittata and Pteris cretica,Cd in Miscanthus sinensis,and Pb,Cr and Mn in moss were the highest.For local free-range chicken and wild passerine bird,the concentrations of PTEs were higher in gastric contents and feather than in internal tissue(stomach,liver and heart),with lower contents in muscle and egg.Bioaccumulation of PTEs generally decreased from decomposer earthworms,to primary producer plants,to top predator,indicating a potential bio-dilution tendency in higher trophic levels in the terrestrial food chain.展开更多
With the advent of the digital era,the field of communications is undergoing profound transformation.Among the most groundbreaking developments is the emergence of non-terrestrial networks(NTN),which represent not onl...With the advent of the digital era,the field of communications is undergoing profound transformation.Among the most groundbreaking developments is the emergence of non-terrestrial networks(NTN),which represent not only a technological leap forward but also a major trend shaping the future of global connectivity.As a layered heterogeneous network,NTN integrates multiple aerial platforms—including satellites,high-altitude platform systems(HAPS),and unmanned aerial systems(UAS)—to provide flexible and composable solutions aimed at achieving seamless worldwide communication coverage.展开更多
The transpiration-to-evapotranspiration ratio(T/ET)is a crucial indicator of the carbon-water cycle and energy balance.Despite the marked seasonality of warming and greening patterns,the differential responses of T/ET...The transpiration-to-evapotranspiration ratio(T/ET)is a crucial indicator of the carbon-water cycle and energy balance.Despite the marked seasonality of warming and greening patterns,the differential responses of T/ET to environmental changes across the seasons remain unclear.To address this,we employed a model-data fusion method,integrating the Priestley–Taylor Jet Propulsion Lab model with observational datasets,to analyze the seasonal trends of T/ET in China’s terrestrial ecosystems from 1981 to 2021.The results showed that T/ET significantly increased in spring,summer,and autumn,with growth rates of 0.0018 a^(–1)(p<0.01),0.0024 a^(–1)(p<0.01),and 0.0013 a^(–1)(p<0.01),respectively,whereas the winter trends remained statistically insignificant throughout the study period.Leaf area index dynamics were identified as the primary driver of the increase in T/ET during summer,accounting for 79%of the trend.By contrast,climate change was the main contributor to the rising T/ET trends in spring and autumn,accounting for 72%and 77%of the T/ET increase,respectively.Additionally,warming is pivotal for climate-driven changes in T/ET trends.This study elucidated seasonal variations in T/ET responses to environmental factors,offering critical insights for the sustainable management of ecosystems and accurate prediction of future environmental change impacts.展开更多
In response to the rise of the energy storage industries such as new energy vehicles and the wide application of lithium in various fields worldwide,the global demand for lithium resources has been in explosive growth...In response to the rise of the energy storage industries such as new energy vehicles and the wide application of lithium in various fields worldwide,the global demand for lithium resources has been in explosive growth.In order to further comprehensively understand the global supply and demand pattern,development and utilization status,genesis of ore deposits and other characteristics of lithium resources,based on the achievements of many researchers at home and abroad,this paper systematically summarized the lithium supply and demand situation,resource endowment,deposit classification and distribution,typical geological characteristics,metallogenic factors and metallogenic regularity of terrestrial brine-type lithium deposits which are the main types of development and utilization all over the world.The review shows that brine-type lithium resource and(or)reserves in the plateau salt lakes are huge and play an important role.In addition,the mineralization potential of the underground brine-type lithium deposit is broad worldwide.The potential resources of underground brines are enormous,and the geothermal spring water type is also worthy of attention.Brine lithium deposits are mainly controlled by the subduction and collision of regional plate tectonics,arid climate and provenance conditions.Strengthening of the scientific research on underground brines in the future is expected to provide another significant support for the global demand for lithium resources.展开更多
The carbon cycle of terrestrial ecosystems is influenced by global climate change and human activities.Using remote sensing data and land cover products,the spatio-temporal variation characteristics and trends of NEP ...The carbon cycle of terrestrial ecosystems is influenced by global climate change and human activities.Using remote sensing data and land cover products,the spatio-temporal variation characteristics and trends of NEP in the Yangtze River Delta from 2000 to 2020 were analyzed based on the soil respiration model.The driving influences of ecosystem structure evolution,temperature,rainfall,and human activities on NEP were studied.The results show that the NEP shows an overall distribution pattern of high in the southeast and low in the northwest.The area of carbon sinks is larger than that of the carbon sources.NEP spatial heterogeneity is significant.NEP change trend is basically unchanged or significantly better.The future change trend in most areas will be continuous decrease.Compared with temperature,NEP are more sensitive to precipitation.The positive influence of human activities on NEP is mainly observed in north-central Anhui and northern Jiangsu coastal areas,while the negative influence is mainly found in highly urbanized areas.In the process of ecosystem structure,the contribution of unchanged areas to NEP change is greater than that of changed areas.展开更多
Changes in water resource storage are inevitable due to climate change and human activities,thus understanding alterations in water storage within a specific region is imperative for the planning and management of wat...Changes in water resource storage are inevitable due to climate change and human activities,thus understanding alterations in water storage within a specific region is imperative for the planning and management of water resources.Data from the Gravity Recovery and Climate Experiment(GRACE)satellite mission are extensively employed to analyze large-scale total terrestrial water storage anomalies(TWSA).In this study,we derived a more reliable TWSA using different types of GRACE gravity models,which served as the basis for evaluating spatial and temporal variations in total terrestrial water storage and its hydrological components(soil moisture and groundwater)across the Loess Plateau.Additionally,we analyzed the impact of natural and anthropogenic influences on water storage in the Loess Plateau,categorizing them into primary and secondary influences,utilizing data on climate and human activities.The findings revealed a declining trend in the overall TWSA of the Loess Plateau,with a rate of decrease at-0.65±0.05 cm/yr from 2003 to 2020(P<0.01).As the direct factors affecting TWSA,soil moisture dominated the change of TWSA before 2009,and groundwater dominated the change of TWSA after 2009.Spatially,there was variability in the changes of TWSA in the Loess Plateau.More in-depth studies showed that soil moisture changes in the study area were primarily driven by evapotranspiration and temperature,with precipitation and vegetation cover status playing a secondary role.Human activities had a secondary effect on soil moisture in some sub-regions.Population change and agricultural development were major factors in altering groundwater storage in the study area.Other than that,groundwater was influenced by natural factors to a limited extent.These findings provided valuable insights for local governments to implement proactive water management policies.展开更多
The construction of dams for intercepting and storing water has altered surface water distributions, landsea water exchanges, and the load response of the solid Earth. The lack of accurate estimation of reservoir prop...The construction of dams for intercepting and storing water has altered surface water distributions, landsea water exchanges, and the load response of the solid Earth. The lack of accurate estimation of reservoir properties through the land surface and hydrological models can lead to water storage simulation and extraction errors. This impact is particularly evident in many artificial reservoirs in China. The study aims to comprehensively assess the spatiotemporal distribution and trends of water storage in medium and large reservoirs(MLRs) in Chinese mainland during 1950-2016, and to investigate the gravity,displacement, and strain effects induced by the reservoir mass concentration using the load elasticity theory. In addition, the impoundment contributions of MLRs to the relative sea level changes were assessed using a sea-level equation. The results show impoundment increases in the MLRs during1950-2016, particularly in the Yangtze River(Changjiang) and southern basins, causing significant elastic load effects in the surrounding areas of the reservoirs and increasing the relative sea level in China's offshore. However, long-term groundwater estimation trends are overestimated and underestimated in the Yangtze River and southwestern basins, respectively, due to the neglect of the MLRs impacts or the uncertainty of the hydrological model's output(e.g., soil moisture, etc.). The construction of MLRs may reduce the water mass input from land to the ocean, thus slowing global sea level rise. The results of the impact of human activities on the regional water cycle provide important references and data support for improving the integration of hydrological models, evaluating Earth's viscoelastic responses under longterm reservoir storage, enhancing in-situ and satellite geodetic measurements, and identifying the main factors driving sea level changes.展开更多
Non-contact remote sensing techniques,such as terrestrial laser scanning(TLS)and unmanned aerial vehicle(UAV)photogrammetry,have been globally applied for landslide monitoring in high and steep mountainous areas.These...Non-contact remote sensing techniques,such as terrestrial laser scanning(TLS)and unmanned aerial vehicle(UAV)photogrammetry,have been globally applied for landslide monitoring in high and steep mountainous areas.These techniques acquire terrain data and enable ground deformation monitoring.However,practical application of these technologies still faces many difficulties due to complex terrain,limited access and dense vegetation.For instance,monitoring high and steep slopes can obstruct the TLS sightline,and the accuracy of the UAV model may be compromised by absence of ground control points(GCPs).This paper proposes a TLS-and UAV-based method for monitoring landslide deformation in high mountain valleys using traditional real-time kinematics(RTK)-based control points(RCPs),low-precision TLS-based control points(TCPs)and assumed control points(ACPs)to achieve high-precision surface deformation analysis under obstructed vision and impassable conditions.The effects of GCP accuracy,GCP quantity and automatic tie point(ATP)quantity on the accuracy of UAV modeling and surface deformation analysis were comprehensively analyzed.The results show that,the proposed method allows for the monitoring accuracy of landslides to exceed the accuracy of the GCPs themselves by adding additional low-accuracy GCPs.The proposed method was implemented for monitoring the Xinhua landslide in Baoxing County,China,and was validated against data from multiple sources.展开更多
As the demands of massive connections and vast coverage rapidly grow in the next wireless communication networks, rate splitting multiple access(RSMA) is considered to be the new promising access scheme since it can p...As the demands of massive connections and vast coverage rapidly grow in the next wireless communication networks, rate splitting multiple access(RSMA) is considered to be the new promising access scheme since it can provide higher efficiency with limited spectrum resources. In this paper, combining spectrum splitting with rate splitting, we propose to allocate resources with traffic offloading in hybrid satellite terrestrial networks. A novel deep reinforcement learning method is adopted to solve this challenging non-convex problem. However, the neverending learning process could prohibit its practical implementation. Therefore, we introduce the switch mechanism to avoid unnecessary learning. Additionally, the QoS constraint in the scheme can rule out unsuccessful transmission. The simulation results validates the energy efficiency performance and the convergence speed of the proposed algorithm.展开更多
Terrestrial water storage(TWs)variations are associated with water mass movements,which may cause the deformation displacements of the Global Navigation Satellite System(GNSS)stations.This study investigates the spati...Terrestrial water storage(TWs)variations are associated with water mass movements,which may cause the deformation displacements of the Global Navigation Satellite System(GNSS)stations.This study investigates the spatio-temporal Tws variations and addresses the relationship between deformation variations observed in the Huang-Huai-Hai River Basin(HHHRB)and local hydrological features.Results indicate that the vertical velocities at the GNSS stations induced by TWS changes are relatively small,and the impacts of the terrestrial water storage changes are mainly reflected in the changes of seasonal characteristics.Although there is a downward TWS trend from 2011 to 2022 in most HHHRB areas,velocities from the vertical displacements of both Gravity Recovery and Climate Experiment(GRACE)and GRACE Follow-On(GFO)and the GNSS reflect that the HHHRB is undergoing an uplift process,while the magnitude of the GRACE/GFO derived velocities is much smaller than that of the GNSS solutions.Common hydrological deformations estimated from GRACE/GFO and GNSS measurements reveal that the TWS-derived displacements can explain 54.5%of the GNSS seasonal variations,with the phases of terrestrial water storage advancing by about one month relative to GNss common signal phases.Moreover,the decrease of the groundwater storage in the HHHRB has been accelerating since 2008.After reaching its lowest level around mid-2020,it began to rise rapidly,which might be closely related to the implementation of the South-North Water Transfer Central Project.展开更多
Vertical forest structure is closely linked to multiple ecosystem characteristics,such as biodiversity,habitat,and productivity.Mixing tree species in planted forests has the potential to create diverse vertical fores...Vertical forest structure is closely linked to multiple ecosystem characteristics,such as biodiversity,habitat,and productivity.Mixing tree species in planted forests has the potential to create diverse vertical forest structures due to the different physiological and morphological traits of the composing tree species.However,the relative importance of species richness,species identity and species interactions for the variation in vertical forest structure remains unclear,mainly because traditional forest inventories do not observe vertical stand structure in detail.Terrestrial laser scanning(TLS),however,allows to study vertical forest structure in an unprecedented way.Therefore,we used TLS single scan data from 126 plots across three experimental planted forests of a largescale tree diversity experiment in Belgium to study the drivers of vertical forest structure.These plots were 9–11years old young pure and mixed forests,characterized by four levels of tree species richness ranging from monocultures to four-species mixtures,across twenty composition levels.We generated vertical plant profiles from the TLS data and derived six stand structural variables.Linear mixed models were used to test the effect of species richness on structural variables.Employing a hierarchical diversity interaction modelling framework,we further assessed species identity effect and various species interaction effects on the six stand structural variables.Our results showed that species richness did not significantly influence most of the stand structure variables,except for canopy height and foliage height diversity.Species identity on the other hand exhibited a significant impact on vertical forest structure across all sites.Species interaction effects were observed to be site-dependent due to varying site conditions and species pools,and rapidly growing tree species tend to dominate these interactions.Overall,our results highlighted the importance of considering both species identity and interaction effects in choosing suitable species combinations for forest management practices aimed at enhancing vertical forest structure.展开更多
Hydrological models are crucial for characterizing large-scale water quantity variations and correcting GNSS reference station vertical displacements.We evaluated the robustness of multiple models,such as the Global L...Hydrological models are crucial for characterizing large-scale water quantity variations and correcting GNSS reference station vertical displacements.We evaluated the robustness of multiple models,such as the Global Land Data Assimilation System (GLDAS),the Famine Early Warning System Network Land Data Assimilation System (FLDAS),the National Centers for Environmental Prediction (NCEP),and the WaterGAP Global Hydrology Model (WGHM).Inter-model and outer comparisons with Global Positioning System (GPS) coordinate time series,satellite gravity field Mascon solutions,and Global Precipitation Climatology Centre (GPCC) guide our assessment.Results confirm WGHM's 26% greater effectiveness in correcting nonlinear variations in GPS height time series compared to NCEP.In the Amazon River Basin,a 5-month lag between FLDAS,GLDAS,and satellite gravity results is observed.In eastern Asia and Australia,NCEP's Terrestrial Water Storage Changes (TWSC)-derived surface displacements correlate differently with precipitation compared to other models.Three combined hydrological models (H-VCE,H-EWM,and H-CVM) utilizing Variance Component Estimation (VCE),Entropy Weight Method (EWM),and Coefficient of Variation Method (CVM) are formulated.Correcting nonlinear variations with combined models enhances global GPS height scatter by 15%-17%.Correlation with precipitation increases by 25%-30%,and with satellite gravity,rises from 0.2 to 0.8 at maximum.The combined model eliminates time lag in the Amazon Basin TWSC analysis,exhibiting a four times higher signal-to-noise ratio than single models.H-VCE demonstrates the highest accuracy.In summary,the combined hydrological model minimizes discrepancies among individual models,significantly improving accuracy for monitoring large-scale TWSC.展开更多
The increasing temperature in the Yellow River Basin has led to a rapid rise in the melting level height,at a rate of 5.98 m yr^(-1)during the cold season,which further contributes to the transition from snowfall to r...The increasing temperature in the Yellow River Basin has led to a rapid rise in the melting level height,at a rate of 5.98 m yr^(-1)during the cold season,which further contributes to the transition from snowfall to rainfall patterns.Between 1979 and 2020,there has been a decrease in snowfall in the Yellow River Basin at a rate of-3.03 mm dec^(-1),while rainfall has been increasing at a rate of 1.00 mm dec^(-1).Consequently,the snowfall-to-rainfall ratio(SRR)has decreased.Snowfall directly replenishes terrestrial water storage(TWS)in solid form until it melts,while rainfall is rapidly lost through runoff and evaporation,in addition to infiltrating underground or remaining on the surface.Therefore,the decreasing SRR accelerates the depletion of water resources.According to the surface water balance equation,the reduction in precipitation and runoff,along with an increase in evaporation,results in a decrease in TWS during the cold season within the Yellow River Basin.In addition to climate change,human activities,considering the region's dense population and extensive agricultural land,also accelerate the decline of TWS.Notably,irrigation accounts for the largest proportion of water withdrawals in the Yellow River Basin(71.8%)and primarily occurs during the warm season(especially from June to August).The impact of human activities and climate change on the water cycle requires further in-depth research.展开更多
文摘With the large-scale deployment of satellite constellations such as Starlink and the rapid advancement of technologies including artificial intelligence (AI) and non-terrestrial networks (NTNs), the integration of high, medium, and low Earth orbit satellite networks with terrestrial networks has become a critical direction for future communication technologies. The objective is to develop a space-terrestrial integrated 6G network that ensures ubiquitous connectivity and seamless services, facilitating intelligent interconnection and collaborative symbiosis among humans, machines, and objects. This integration has become a central focus of global technological innovation.
基金supported by the Chinese Scholarship Council under Grant 202106910006.
文摘Branch angles are an important plant morphological trait affecting light interception within forest canopies.However,studies on branch angles have been limited due to the time-consuming nature of manual measurements using a protractor.Terrestrial laser scanning(TLS),however,provides new opportunities to measure branch angles more efficiently.Despite this potential,studies validating branch angle measurements from TLS have been limited.Here,our aim is to evaluate both manual and automatic branch angle measurements of European beech from TLS data using traditional field-measurements with a protractor as a reference.We evaluated the accuracy of branch angle measurements based on four automated algorithms(aRchiQSM,TreeQSM,Laplacian,SemanticLaplacian)from TLS data.Additionally,we assessed different ways of manual branch angle measurements in the field.Our study was based on a dataset comprising 124 branch angles measured from six European beech in a European deciduous forest.Our results show that manual branch angle measurements from TLS data are in high agreement with the reference(root-mean-squared error,RMSE:[3.57°-4.18°],concordance correlation coefficient,CCC:[0.950.97])across different branch length positions.Automated algorithms also are in high agreement with the reference although RMSE is approximately twice as large compared to manual branch angle measurements from TLS(RMSE:[9.29°-10.55°],CCC:[0.830.86])with manual leaf points removal.When applying the automatic wood-leaf separation algorithm,the performance of the four methods declined significantly,with only approximately 20 branch angles successfully identified.Moreover,it is important to note that there is no influence of the measurement position(branch surface versus center)for branch angle measurements.However,for curved branches,the selection of branch measurement length significantly impacts the branch angle measurement.This study provides a comprehensive understanding of branch angle measurements in forests.We show that automated measurement methods based on TLS data of branch angles are a valuable tool to quantify branch angles at larger scales.
基金co-supported by the National Natural Science Foundation of China(Nos.62225103,U2441227,U24A20211)the Fundamental Research Funds for the Central Universities of China(No.FRF-TP-22-002C2)。
文摘1.Introduction As a key development of the next-generation spatial information infrastructure,1the Satellite-Terrestrial Integrated Network(STIN)has become a strategic priority actively pursued by major spacefaring nations and regions,including the United States,Europe,China,and Russia.Specifically,Space X’s Starlink project has deployed over 6750 satellites,2while One Web has completed its initial phase of satellite constellation deployment with more than 600 satellites.
基金funded by the Postdoctoral Research Startup Foundation of University of Jinan(Grant No.100389917).
文摘Climate change and anthropogenic activities have driven significant terrestrial water storage changes(TWSC)in the Three Rivers Source Region(TRSR),exerting profound impacts on freshwater availability across China and broader Asia.However,long-term TWSC characterization remains challenging due to limited observational data in this alpine region.Here,we integrate GRACE observations(2002-2020),ERA5-Land reanalysis,and GLDAS data to reconstruct TWSC using two methods:(1)the water balance method(PER)and(2)the component summation method(SS),applied to three input datasets(ERA5-Land,GLDAS,and their average,GLER).Comparative analysis reveals that the SS method applied to GL-ER yields the highest consistency with GRACE-derived TWSC.Using this optimal approach,we extend the analysis to 1951~2020,uncovering spatiotemporal TWSC patterns.Although annual TWSC trends appear negligible due to strong seasonality,we introduce the intra-year TWSC fluctuation(TWSCF)index to quantify cumulative variability.A significant(p<0.05)transition occurred in 1980,with TWSCF shifting from a declining trend(-0.39 mm/yr)to an increasing trend(0.56 mm/yr),primarily driven by soil moisture changes.However,Hurst exponent analysis suggests this upward trend may not persist.Drought and vegetation assessments indicate concurrent wetting and greening in the TRSR.TWSC correlates strongly with meteorological drought,acting as a reliable drought indicator while its linkage with vegetation dynamics suggests a potential contribution to greening.Our findings provide a robust framework for understanding long-term TWSC evolution and its hydrological-ecological interactions under climate change.
基金the funding of the National Natural Science Foundation of China(Nos.42222209,42303056)。
文摘The rhenium-osmium(Re-Os)isotope system is a powerful tool for dating organic-rich sedimentary rocks,yet the mechanisms of Re and Os uptake and their fractionation in different types of organic matter remain poorly understood.Here,we investigate the role of terrestrial organic matter(e.g.,wood of the species Taxodium distichum and charcoal generated from the same species in the laboratory)in Re and Os enrichment and isotope fractionation through laboratory experiments.The results show that charcoal has a significantly higher capacity to uptake both Re(68-77 times greater)and Os(1.7-2.2 times higher)compared to wood,with charcoal preferentially accumulating Re over Os,leading to higher^(187)Re/^(188)Os ratios.These findings highlight the important contribution of terrestrial organic matter,particularly charcoal,to Re and Os concentrations and isotope fractionation in shales,and the importance of organic matter type for chelating Re and Os as previously discussed.Furthermore,we discuss the potential of using Re to track organic carbon weathering,noting that the coupled release of Re and organic carbon during weathering provides new insights into carbon cycling processes.
基金Earthquake Science and Technology Program of Hebei Province under Grant Nos.DZ2021120300001,DZ2024083000001,DZ2024112400016 and DZ2025092800001。
文摘In this study,terrestrial laser scanning(TLS)is used to collect building data after the M_(s) 7.0 magnitude earthquake in Lushan,Sichuan,China in 2013 for analysis and research.The analysis focuses on extracting the tilt and deformation of masonry buildings that are difficult to identify through visual inspection in basically intact,slightly damaged and moderately damaged masonry buildings,to solve the problem of ambiguous identification of damage.A quantitative analysis of the determination indexes of the degree of earthquake damage was carried out,and the numerical characteristics parameters such as the curvature of the wall point cloud proximity,angle,contour of the fitted plane of the point cloud,verticality(flatness)of the wall,standard deviation of the profile and angle of the profile were established to determine the degree of earthquake damage to buildings based on LiDAR data.The development of quantitative determination indexes for the degree of earthquake damage of buildings in this study has important application value for LiDAR data in the identification and extraction of earthquake damage information and damage level determination.
基金funded by State Key Laboratory of Micro-Spacecraft Rapid Design and Intelligent Cluster under Grant MS01240103the National Natural Science Foundation of China under Grant 62071146National 2011 Collaborative Innovation Center of Wireless Communication Technologies under Grant 2242022k60006.
文摘In this paper,we propose a joint power and frequency allocation algorithm considering interference protection in the integrated satellite and terrestrial network(ISTN).We efficiently utilize spectrum resources by allowing user equipment(UE)of terrestrial networks to share frequencies with satellite networks.In order to protect the satellite terminal(ST),the base station(BS)needs to control the transmit power and frequency resources of the UE.The optimization problem involves maximizing the achievable throughput while satisfying the interference protection constraints of the ST and the quality of service(QoS)of the UE.However,this problem is highly nonconvex,and we decompose it into power allocation and frequency resource scheduling subproblems.In the power allocation subproblem,we propose a power allocation algorithm based on interference probability(PAIP)to address channel uncertainty.We obtain the suboptimal power allocation solution through iterative optimization.In the frequency resource scheduling subproblem,we develop a heuristic algorithm to handle the non-convexity of the problem.The simulation results show that the combination of power allocation and frequency resource scheduling algorithms can improve spectrum utilization.
基金supported by the National Natural Science Foundation of China(Nos.41907325 and 41571470).
文摘The present study was conducted to examine the trophic transfer of potentially toxic elements(PTEs)in a closed arsenic mine.Eight PTEs in a soil-plant-leaf litter-earthworm-top predators(free-range local chicken and wild passerine bird)system were analyzed for nitrogen and carbon stable isotopes,PTE concentrations,bioaccumulation factors(BAFs),and transfer factors(TFs).The PTE concentrations in soils from mining areas were generally higher than a adjacent controlled area,with As and Cd in soils showing the prominent compared to other six PTEs,as seen for the indices of geo-accumulation index(I_(geo)),pollution index(PI)and potential ecological risk index(RI).The relatively high BAF and TF values suggested a distinct biotransfer of PTEs along the soil-plant-leaf litter-earthworm system.BAFs were mostly<1 except in earthworms,indicating that earthworms had a strong capacity to take up these metals.The TFs varied both among PTEs and organism’s species,e.g.,the transfer capacities of As in Pteris vittata and Pteris cretica,Cd in Miscanthus sinensis,and Pb,Cr and Mn in moss were the highest.For local free-range chicken and wild passerine bird,the concentrations of PTEs were higher in gastric contents and feather than in internal tissue(stomach,liver and heart),with lower contents in muscle and egg.Bioaccumulation of PTEs generally decreased from decomposer earthworms,to primary producer plants,to top predator,indicating a potential bio-dilution tendency in higher trophic levels in the terrestrial food chain.
文摘With the advent of the digital era,the field of communications is undergoing profound transformation.Among the most groundbreaking developments is the emergence of non-terrestrial networks(NTN),which represent not only a technological leap forward but also a major trend shaping the future of global connectivity.As a layered heterogeneous network,NTN integrates multiple aerial platforms—including satellites,high-altitude platform systems(HAPS),and unmanned aerial systems(UAS)—to provide flexible and composable solutions aimed at achieving seamless worldwide communication coverage.
基金National Natural Science Foundation of China,No.42201312,No.42301538Natural Science Foundation of Shandong Province,No.ZR2022QD118。
文摘The transpiration-to-evapotranspiration ratio(T/ET)is a crucial indicator of the carbon-water cycle and energy balance.Despite the marked seasonality of warming and greening patterns,the differential responses of T/ET to environmental changes across the seasons remain unclear.To address this,we employed a model-data fusion method,integrating the Priestley–Taylor Jet Propulsion Lab model with observational datasets,to analyze the seasonal trends of T/ET in China’s terrestrial ecosystems from 1981 to 2021.The results showed that T/ET significantly increased in spring,summer,and autumn,with growth rates of 0.0018 a^(–1)(p<0.01),0.0024 a^(–1)(p<0.01),and 0.0013 a^(–1)(p<0.01),respectively,whereas the winter trends remained statistically insignificant throughout the study period.Leaf area index dynamics were identified as the primary driver of the increase in T/ET during summer,accounting for 79%of the trend.By contrast,climate change was the main contributor to the rising T/ET trends in spring and autumn,accounting for 72%and 77%of the T/ET increase,respectively.Additionally,warming is pivotal for climate-driven changes in T/ET trends.This study elucidated seasonal variations in T/ET responses to environmental factors,offering critical insights for the sustainable management of ecosystems and accurate prediction of future environmental change impacts.
基金This study was jointly supported by Central Welfare Basic Scientific Research Business Expenses(KK2005,YYWF201607)the project of the industrial leading talant of Wuhan municipality of Hubei Province,the Editor of China Geology,Rui-qin Li,and many thanks for a nice review by anonymous reviewers.
文摘In response to the rise of the energy storage industries such as new energy vehicles and the wide application of lithium in various fields worldwide,the global demand for lithium resources has been in explosive growth.In order to further comprehensively understand the global supply and demand pattern,development and utilization status,genesis of ore deposits and other characteristics of lithium resources,based on the achievements of many researchers at home and abroad,this paper systematically summarized the lithium supply and demand situation,resource endowment,deposit classification and distribution,typical geological characteristics,metallogenic factors and metallogenic regularity of terrestrial brine-type lithium deposits which are the main types of development and utilization all over the world.The review shows that brine-type lithium resource and(or)reserves in the plateau salt lakes are huge and play an important role.In addition,the mineralization potential of the underground brine-type lithium deposit is broad worldwide.The potential resources of underground brines are enormous,and the geothermal spring water type is also worthy of attention.Brine lithium deposits are mainly controlled by the subduction and collision of regional plate tectonics,arid climate and provenance conditions.Strengthening of the scientific research on underground brines in the future is expected to provide another significant support for the global demand for lithium resources.
基金National Key R&D Program of China,No.2018YFD1100101。
文摘The carbon cycle of terrestrial ecosystems is influenced by global climate change and human activities.Using remote sensing data and land cover products,the spatio-temporal variation characteristics and trends of NEP in the Yangtze River Delta from 2000 to 2020 were analyzed based on the soil respiration model.The driving influences of ecosystem structure evolution,temperature,rainfall,and human activities on NEP were studied.The results show that the NEP shows an overall distribution pattern of high in the southeast and low in the northwest.The area of carbon sinks is larger than that of the carbon sources.NEP spatial heterogeneity is significant.NEP change trend is basically unchanged or significantly better.The future change trend in most areas will be continuous decrease.Compared with temperature,NEP are more sensitive to precipitation.The positive influence of human activities on NEP is mainly observed in north-central Anhui and northern Jiangsu coastal areas,while the negative influence is mainly found in highly urbanized areas.In the process of ecosystem structure,the contribution of unchanged areas to NEP change is greater than that of changed areas.
基金supported in part by the National Natural Science Foundation of China under Grant 42374037the State Key Laboratory of Geodesy and Earth’s Dynamics,Innovation Academy for Precision Measurement Science and Technology under Grant SKLGED2022-3-5in part by the Outstanding Youth Science Fund of Xi’an University of Science and Technology under Grant 2018YQ2-10。
文摘Changes in water resource storage are inevitable due to climate change and human activities,thus understanding alterations in water storage within a specific region is imperative for the planning and management of water resources.Data from the Gravity Recovery and Climate Experiment(GRACE)satellite mission are extensively employed to analyze large-scale total terrestrial water storage anomalies(TWSA).In this study,we derived a more reliable TWSA using different types of GRACE gravity models,which served as the basis for evaluating spatial and temporal variations in total terrestrial water storage and its hydrological components(soil moisture and groundwater)across the Loess Plateau.Additionally,we analyzed the impact of natural and anthropogenic influences on water storage in the Loess Plateau,categorizing them into primary and secondary influences,utilizing data on climate and human activities.The findings revealed a declining trend in the overall TWSA of the Loess Plateau,with a rate of decrease at-0.65±0.05 cm/yr from 2003 to 2020(P<0.01).As the direct factors affecting TWSA,soil moisture dominated the change of TWSA before 2009,and groundwater dominated the change of TWSA after 2009.Spatially,there was variability in the changes of TWSA in the Loess Plateau.More in-depth studies showed that soil moisture changes in the study area were primarily driven by evapotranspiration and temperature,with precipitation and vegetation cover status playing a secondary role.Human activities had a secondary effect on soil moisture in some sub-regions.Population change and agricultural development were major factors in altering groundwater storage in the study area.Other than that,groundwater was influenced by natural factors to a limited extent.These findings provided valuable insights for local governments to implement proactive water management policies.
基金supported by the National Natural Science Foundation of China (No.42274110 and 42374106)long-term monitoring project in the Three Gorges Reservoir area (the National Natural Science Foundation of China,No.41874090 and 41504065)。
文摘The construction of dams for intercepting and storing water has altered surface water distributions, landsea water exchanges, and the load response of the solid Earth. The lack of accurate estimation of reservoir properties through the land surface and hydrological models can lead to water storage simulation and extraction errors. This impact is particularly evident in many artificial reservoirs in China. The study aims to comprehensively assess the spatiotemporal distribution and trends of water storage in medium and large reservoirs(MLRs) in Chinese mainland during 1950-2016, and to investigate the gravity,displacement, and strain effects induced by the reservoir mass concentration using the load elasticity theory. In addition, the impoundment contributions of MLRs to the relative sea level changes were assessed using a sea-level equation. The results show impoundment increases in the MLRs during1950-2016, particularly in the Yangtze River(Changjiang) and southern basins, causing significant elastic load effects in the surrounding areas of the reservoirs and increasing the relative sea level in China's offshore. However, long-term groundwater estimation trends are overestimated and underestimated in the Yangtze River and southwestern basins, respectively, due to the neglect of the MLRs impacts or the uncertainty of the hydrological model's output(e.g., soil moisture, etc.). The construction of MLRs may reduce the water mass input from land to the ocean, thus slowing global sea level rise. The results of the impact of human activities on the regional water cycle provide important references and data support for improving the integration of hydrological models, evaluating Earth's viscoelastic responses under longterm reservoir storage, enhancing in-situ and satellite geodetic measurements, and identifying the main factors driving sea level changes.
基金support of the National Natural Science Foundation of China(Grant Nos.U2240221 and 41977229)the Sichuan Youth Science and Technology Innovation Research Team Project(Grant No.2020JDTD0006).
文摘Non-contact remote sensing techniques,such as terrestrial laser scanning(TLS)and unmanned aerial vehicle(UAV)photogrammetry,have been globally applied for landslide monitoring in high and steep mountainous areas.These techniques acquire terrain data and enable ground deformation monitoring.However,practical application of these technologies still faces many difficulties due to complex terrain,limited access and dense vegetation.For instance,monitoring high and steep slopes can obstruct the TLS sightline,and the accuracy of the UAV model may be compromised by absence of ground control points(GCPs).This paper proposes a TLS-and UAV-based method for monitoring landslide deformation in high mountain valleys using traditional real-time kinematics(RTK)-based control points(RCPs),low-precision TLS-based control points(TCPs)and assumed control points(ACPs)to achieve high-precision surface deformation analysis under obstructed vision and impassable conditions.The effects of GCP accuracy,GCP quantity and automatic tie point(ATP)quantity on the accuracy of UAV modeling and surface deformation analysis were comprehensively analyzed.The results show that,the proposed method allows for the monitoring accuracy of landslides to exceed the accuracy of the GCPs themselves by adding additional low-accuracy GCPs.The proposed method was implemented for monitoring the Xinhua landslide in Baoxing County,China,and was validated against data from multiple sources.
文摘As the demands of massive connections and vast coverage rapidly grow in the next wireless communication networks, rate splitting multiple access(RSMA) is considered to be the new promising access scheme since it can provide higher efficiency with limited spectrum resources. In this paper, combining spectrum splitting with rate splitting, we propose to allocate resources with traffic offloading in hybrid satellite terrestrial networks. A novel deep reinforcement learning method is adopted to solve this challenging non-convex problem. However, the neverending learning process could prohibit its practical implementation. Therefore, we introduce the switch mechanism to avoid unnecessary learning. Additionally, the QoS constraint in the scheme can rule out unsuccessful transmission. The simulation results validates the energy efficiency performance and the convergence speed of the proposed algorithm.
基金funded by the National Natural Science Foundation of China (NO. 42104028, 42174030 and 42004017)the Project Supported by the Open Fund of Hubei Luojia Laboratory (Grant No. 220100048 and 230100021)Program for Hubei Provincial Science and Technology Innovation Talents (Grant No. 2022EJD010)
文摘Terrestrial water storage(TWs)variations are associated with water mass movements,which may cause the deformation displacements of the Global Navigation Satellite System(GNSS)stations.This study investigates the spatio-temporal Tws variations and addresses the relationship between deformation variations observed in the Huang-Huai-Hai River Basin(HHHRB)and local hydrological features.Results indicate that the vertical velocities at the GNSS stations induced by TWS changes are relatively small,and the impacts of the terrestrial water storage changes are mainly reflected in the changes of seasonal characteristics.Although there is a downward TWS trend from 2011 to 2022 in most HHHRB areas,velocities from the vertical displacements of both Gravity Recovery and Climate Experiment(GRACE)and GRACE Follow-On(GFO)and the GNSS reflect that the HHHRB is undergoing an uplift process,while the magnitude of the GRACE/GFO derived velocities is much smaller than that of the GNSS solutions.Common hydrological deformations estimated from GRACE/GFO and GNSS measurements reveal that the TWS-derived displacements can explain 54.5%of the GNSS seasonal variations,with the phases of terrestrial water storage advancing by about one month relative to GNss common signal phases.Moreover,the decrease of the groundwater storage in the HHHRB has been accelerating since 2008.After reaching its lowest level around mid-2020,it began to rise rapidly,which might be closely related to the implementation of the South-North Water Transfer Central Project.
基金Mengxi Wang holds a doctoral scholarship from the China scholarship council(CSC:202003270025)。
文摘Vertical forest structure is closely linked to multiple ecosystem characteristics,such as biodiversity,habitat,and productivity.Mixing tree species in planted forests has the potential to create diverse vertical forest structures due to the different physiological and morphological traits of the composing tree species.However,the relative importance of species richness,species identity and species interactions for the variation in vertical forest structure remains unclear,mainly because traditional forest inventories do not observe vertical stand structure in detail.Terrestrial laser scanning(TLS),however,allows to study vertical forest structure in an unprecedented way.Therefore,we used TLS single scan data from 126 plots across three experimental planted forests of a largescale tree diversity experiment in Belgium to study the drivers of vertical forest structure.These plots were 9–11years old young pure and mixed forests,characterized by four levels of tree species richness ranging from monocultures to four-species mixtures,across twenty composition levels.We generated vertical plant profiles from the TLS data and derived six stand structural variables.Linear mixed models were used to test the effect of species richness on structural variables.Employing a hierarchical diversity interaction modelling framework,we further assessed species identity effect and various species interaction effects on the six stand structural variables.Our results showed that species richness did not significantly influence most of the stand structure variables,except for canopy height and foliage height diversity.Species identity on the other hand exhibited a significant impact on vertical forest structure across all sites.Species interaction effects were observed to be site-dependent due to varying site conditions and species pools,and rapidly growing tree species tend to dominate these interactions.Overall,our results highlighted the importance of considering both species identity and interaction effects in choosing suitable species combinations for forest management practices aimed at enhancing vertical forest structure.
基金funded by the National Natural Science Foundation of China (42174030)Major Science and Technology Program for Hubei Province (Grant No.2022AAA002)+2 种基金Special fund of Hubei Luojia Loboratory (220100020)the National Natural Science Foundation of China under Grant 42304031the China Postdoctoral Science Foundation 2022M722441。
文摘Hydrological models are crucial for characterizing large-scale water quantity variations and correcting GNSS reference station vertical displacements.We evaluated the robustness of multiple models,such as the Global Land Data Assimilation System (GLDAS),the Famine Early Warning System Network Land Data Assimilation System (FLDAS),the National Centers for Environmental Prediction (NCEP),and the WaterGAP Global Hydrology Model (WGHM).Inter-model and outer comparisons with Global Positioning System (GPS) coordinate time series,satellite gravity field Mascon solutions,and Global Precipitation Climatology Centre (GPCC) guide our assessment.Results confirm WGHM's 26% greater effectiveness in correcting nonlinear variations in GPS height time series compared to NCEP.In the Amazon River Basin,a 5-month lag between FLDAS,GLDAS,and satellite gravity results is observed.In eastern Asia and Australia,NCEP's Terrestrial Water Storage Changes (TWSC)-derived surface displacements correlate differently with precipitation compared to other models.Three combined hydrological models (H-VCE,H-EWM,and H-CVM) utilizing Variance Component Estimation (VCE),Entropy Weight Method (EWM),and Coefficient of Variation Method (CVM) are formulated.Correcting nonlinear variations with combined models enhances global GPS height scatter by 15%-17%.Correlation with precipitation increases by 25%-30%,and with satellite gravity,rises from 0.2 to 0.8 at maximum.The combined model eliminates time lag in the Amazon Basin TWSC analysis,exhibiting a four times higher signal-to-noise ratio than single models.H-VCE demonstrates the highest accuracy.In summary,the combined hydrological model minimizes discrepancies among individual models,significantly improving accuracy for monitoring large-scale TWSC.
基金National Natural Science Foundation of China (42041004)。
文摘The increasing temperature in the Yellow River Basin has led to a rapid rise in the melting level height,at a rate of 5.98 m yr^(-1)during the cold season,which further contributes to the transition from snowfall to rainfall patterns.Between 1979 and 2020,there has been a decrease in snowfall in the Yellow River Basin at a rate of-3.03 mm dec^(-1),while rainfall has been increasing at a rate of 1.00 mm dec^(-1).Consequently,the snowfall-to-rainfall ratio(SRR)has decreased.Snowfall directly replenishes terrestrial water storage(TWS)in solid form until it melts,while rainfall is rapidly lost through runoff and evaporation,in addition to infiltrating underground or remaining on the surface.Therefore,the decreasing SRR accelerates the depletion of water resources.According to the surface water balance equation,the reduction in precipitation and runoff,along with an increase in evaporation,results in a decrease in TWS during the cold season within the Yellow River Basin.In addition to climate change,human activities,considering the region's dense population and extensive agricultural land,also accelerate the decline of TWS.Notably,irrigation accounts for the largest proportion of water withdrawals in the Yellow River Basin(71.8%)and primarily occurs during the warm season(especially from June to August).The impact of human activities and climate change on the water cycle requires further in-depth research.
