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Quantifying spatial variations and dynamics of the quality of urban human settlement in China 认领 引用
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作者 TONG Luyi ZHANG Xiaolong +2 位作者 CHEN Panyu LUO Su ZHANG Bin 《Journal of Geographical Sciences》 SCIE CSCD 2026年第6期1323-1342,共20页
Urbanization in China has rapidly reshaped the quality of human settlement;however,most studies have overlooked its continuous spatiotemporal evolutionary characteristics.This study develops a hierarchical framework i... Urbanization in China has rapidly reshaped the quality of human settlement;however,most studies have overlooked its continuous spatiotemporal evolutionary characteristics.This study develops a hierarchical framework integrating TOPSIS,spatial autocorrelation,Theil index decomposition,and time series analysis to quantify comprehensive and subsystem-level quality of urban human settlement(QUHS)for 264 Chinese cities from 2002 to 2021.This framework captures spatial heterogeneity,temporal trends,and variations across residential environments,public services,socioeconomic development,and the natural environment,offering a more nuanced understanding than conventional cross-sectional approaches.The results indicate a steady improvement in QUHS nationwide,with pronounced spatial clustering and belt-like regional patterns:cities in the eastern and southern regions advanced more rapidly,whereas those in the northwestern and northeastern regions lagged.Although regional disparities decreased overall,considerable intra-regional differences persisted,highlighting their role in shaping spatial inequality.Based on these findings,initiatives such as ecological civilization promotion,digital economic development,infrastructure upgrades,and regional integration could contribute to improving QUHS;however,persistent intercity differences emphasize the need for regionally tailored and locally adaptive policy measures.By revealing the dynamic evolution and spatial heterogeneity of QUHS,this study enhances understanding of urban sustainability and provides evidence-based insights for planning and policymaking in rapidly urbanizing contexts. 展开更多
关键词 quality of urban human settlement spatial variations dynamic trends time series analysis China
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Grain Size Characteristics and Spatial Variation of Sediments in Taklamakan Sand Sea,China 认领 引用
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作者 WANG Siqi ZHANG Zhengcai +3 位作者 DONG Zhibao PAN Kaijia ZHANG Yan LIU Ting 《Chinese Geographical Science》 SCIE CAS CSCD 2026年第5期772-784,共13页
Grain size in aeolian sediments is fundamental to studying geomorphic evolution,arising from interactions among fluvial deposits,sediment sources and aeolian airflow.Previous studies on grain size in the Taklamakan Sa... Grain size in aeolian sediments is fundamental to studying geomorphic evolution,arising from interactions among fluvial deposits,sediment sources and aeolian airflow.Previous studies on grain size in the Taklamakan Sand Sea of China have mainly focused on individual dunes,overlooking variations among different dune types.Although spatial patterns of grain size parameters are well-documented in other Chinese deserts,they remain poorly understood in the Taklamakan.To supplement this aspect,700 surface sediment samples were collected from the Taklamakan Sand Sea,including transverse dunes,linear dunes,pyramid dunes,reticulate dunes,vegetated dunes and interdune areas,to characterize grain size distribution across dune types and the sand sea.The Taklamakan Sand Sea is dominated by fine sand and very fine sand,with minimal proportions of coarse sand and larger fractions,suggesting that sand transport predominantly occurs through saltation.Grain size characteristics differ significantly among dune types,indicating that grain size characteristics may be a dune classification index in geomorphology.The significant correlation between the grain size characteristics of transverse dunes and linear dunes suggests a possible transformation relationship between these dune types in the Taklamakan Sand Sea.Spatial variations in grain size are controlled by dune type,local geomorphology,and wind regimes.Higher wind speed in the east caused the mean grain size of aeolian sands to decrease from east to west along the northeast wind.Sand sorting decreases from east to west and then increases,whereas skewness and kurtosis show no clear spatial trends.Overall,distinct grain size variations among dune types reveal previously unrecognized evolutionary connections between aeolian landforms.The spatial distribution of grain size parameters clarifies sediment provenance and transport processes in the Taklamakan Sand Sea. 展开更多
关键词 grain size aeolian sediments dune types spatial variation Taklamakan Sand Sea,China
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Analysis of Spatial Variation Characteristics of Soil Nutrients and Evaluation of Soil Fertility in Small-scale Mountain Tea Gardens 认领 引用
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作者 Xiangping LI Yu DING +3 位作者 Zhiming MU Xiang FANG Haiyan LIU Qinhong LIAO 《Asian Agricultural Research》 2025年第12期38-45,共8页
[Objectives]To elucidate the spatial variation characteristics and fertility status of soil nutrients in small-scale mountain tea gardens and to inform precise fertilization and nutrient management practices in these ... [Objectives]To elucidate the spatial variation characteristics and fertility status of soil nutrients in small-scale mountain tea gardens and to inform precise fertilization and nutrient management practices in these tea gardens.[Methods]Based on soil nutrient data collected from 72 sampling points in the tea garden in 2021,which covers an area of approximately 2.4 km2,the spatial variation characteristics were analyzed using geostatistical methods.Spatial distribution maps of soil pH,total nitrogen,available phosphorus,and available potassium were generated employing the ordinary Kriging interpolation method in Surfer 23 software.Furthermore,a quantitative assessment of soil fertility was performed utilizing the fuzzy comprehensive evaluation method.[Results]The majority of the soil in the tea garden was acidic.The average values for pH,organic matter,total nitrogen,available phosphorus,and available potassium were 4.66,14.4 g/kg,0.9 g/kg,6.2 mg/kg,and 78.1 mg/kg,respectively.The pH exhibited the lowest coefficient of variation at 12.85%,indicating low variability.The coefficients of variation for organic matter,total nitrogen,and available potassium ranged from 31.94%to 49.88%,reflecting moderate variability.In contrast,the coefficient of variation for available phosphorus was 243.41%,indicating high variability.The distribution of soil pH and available phosphorus in the study area was relatively uniform.In contrast,total nitrogen content exhibited a spatial pattern characterized by higher concentrations in the western region and lower concentrations in the eastern region.Organic matter content displayed a spatial distribution pattern with lower values centrally and higher values along the periphery.The distribution of available potassium content was marked by several pronounced"elevations"and"depressions",with notably lower levels observed in the northeastern region of the garden.Total nitrogen and organic matter were the most significant contributors to the integrated fertility index(IIFI),each with a weight value of 0.29,whereas pH had the lowest weight value of 0.14.The proportions of tea garden soils categorized under IIFIgrades I to V were 0.26%,69.55%,25.89%,4.30%,and 0.0022%,respectively.[Conclusions]It is recommended that the application of phosphorus fertilizer should be reduced in the study area,whereas the use of potassium fertilizer should be increased in the northeastern region.Additionally,the incorporation of organic and nitrogen fertilizers is advised to improve the soil s capacity for water and nutrient retention. 展开更多
关键词 Tea garden Soil nutrient Spatial variation Fertility evaluation
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Temporal and Spatial Variations in the Concentration of Negative Ions and Its Influencing Factors in Xinfeng County 认领 引用
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作者 Yiping LIN Xuanying XIE +1 位作者 Liqing ZHOU Liwen YE 《Meteorological and Environmental Research》 2025年第1期41-43,48,共3页
Based on the data of meteorological elements and concentration of negative ions in the county town station,Luguhe station and Yunjishan station during 2020-2024,the temporal and spatial variations in the concentration... Based on the data of meteorological elements and concentration of negative ions in the county town station,Luguhe station and Yunjishan station during 2020-2024,the temporal and spatial variations in the concentration of negative ions and their influencing factors in Xinfeng County were analyzed.The results show that the concentration of negative ions was the highest in summer,followed by spring;it was lower in autumn and the lowest in winter.In terms of diurnal variations,it was higher in the early morning and night,and lower in the noon and afternoon,which was closely related to the diurnal variations of human activities and meteorological conditions.The factors that affect the concentration of negative ions in the air are more complex.Besides meteorological factors,vegetation,altitude,human activities and other factors should be considered. 展开更多
关键词 Concentration of negative ions Temporal and spatial variations Influencing factors Xinfeng County
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Slope spectrum critical area and its spatial variation in the Loess Plateau of China 认领 引用 被引量：28
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作者 TANG Guoan SONG Xiaodong +2 位作者 LI Fayuan ZHANG Yong XION-GLiyang 《Journal of Geographical Sciences》 SCIE CSCD 2015年第12期1452-1466,共15页
Slope spectrum has been proved to be a significant methodology in revealing geomorphological features in the study of Chinese loess terrain. The determination of critical areas in deriving slope spectra is an indispen... Slope spectrum has been proved to be a significant methodology in revealing geomorphological features in the study of Chinese loess terrain. The determination of critical areas in deriving slope spectra is an indispensable task. Along with the increase in the size of the study area, the derived spectra are becoming more and more alike, such that their dif- ferences can be ignored in favor of a standard. Subsequently, the test size is defined as the Slope Spectrum Critical Area （SSCA）. SSCA is not only the foundation of the slope spectrum calculation but also, to some extent, a reflection of geomorphological development of loess relief. High resolution DEMs are important in extracting the slope spectrum. A set of 48 DEMs with different landform areas of the Loess Plateau in northern Shaanxi province was selected for the experiment. The spatial distribution of SSCA is investigated with a geo-statistical analysis method, resulting in values ranging from 6.18 km^2 to 35.1 km^2. Primary experimental results show that the spatial distribution of SSCA is correlated with the spatial distribution of the soil erosion intensity, to a certain extent reflecting the terrain complexity. The critical area of the slope spectrum presents a spatial variation trend of weak-strong-weak from north to south. Four terrain parameters, gully density, slope skewness, terrain driving force （Td） and slope of slope （SOS）, were chosen as indicators. There exists a good exponential function relationship between SSCA and gully density, terrain driving force （Td） and SOS and a loga- rithmic function relationship between SSCA and slope skewness. Slope skewness increases, and gully density, terrain driving force and SOS decrease with increasing SSCA. SSCA can be utilized as a discriminating factor to identify loess landforms, in that spatial distributions of SSCA and the evolution of loess landforms are correlative. Following the evolution of a loess landform from tableland to gully-hilly region, this also proves that SSCA can represent the development degree of local landforms. The critical stable regions of the Loess Plateau represent the degree of development of loess landforms. Its chief significance is that the per- ception of stable areas can be used to determine the minimal geographical unit. 展开更多
关键词 digital elevation model slope spectrum critical area spatial variation independent geomorphological unit Loess Plateau
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Quantifying the spatial variation in the potential productivity and yield gap of winter wheat in China 认领 引用 被引量：15
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作者 ZHANG Shi-yuan ZHANG Xiao-hu +4 位作者 QIU Xiao-lei TANG Liang ZHU Yan CAO Wei-xing LIU Lei-lei 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2017年第4期845-857,共13页
Despite the improvement in cultivar characters and management practices, large gaps between the attainable and potential yields still exist in winter wheat of China. Quantifying the crop potential yield is essential f... Despite the improvement in cultivar characters and management practices, large gaps between the attainable and potential yields still exist in winter wheat of China. Quantifying the crop potential yield is essential for estimating the food production capacity and improving agricultural policies to ensure food security. Gradually descending models and geographic infor- mation system （GIS） technology were employed to characterize the spatial variability of potential yields and yield gaps in winter wheat across the main production region of China. The results showed that during 2000-2010, the average potential yield limited by thermal resource （YGT） was 23.2 Mg ha-1, with larger value in the northern area relative to the southern area. The potential yield limited by the water supply （YGw） generally decreased from north to south, with an average value of 1.9 Mg ha-1 across the entire study region. The highest YGw in the north sub-region （NS） implied that the irrigation and drainage conditions in this sub-region must be improved. The averaged yield loss of winter wheat from nutrient deficiency （YGH） varied between 2.1 and 3.1 Mg ha-1 in the study area, which was greater than the yield loss caused by water limitation. The potential decrease in yield from photo-thermal-water-nutrient-limited production to actual yield （YGo） was over 6.0 Mg ha-1, ranging from 4.9 to 8.3 Mg ha^-1 across the entire study region, and it was more obvious in the southern area than in the northern area. These findings suggest that across the main winter wheat production region, the highest yield gap was induced by thermal resources, followed by other factors, such as the level of farming technology, social policy and economic feasibility. Furthermore, there are opportunities to narrow the yield gaps by making full use of climatic resources and developing a reasonable production plan for winter wheat crops. Thus, meeting the challenges of food security and sustainability in the coming decades is possible but will require considerable changes in water and nutrient management and socio-economic policies. 展开更多
关键词 spatial variation potential productivity yield gap winter wheat China
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Spatial variation in annual actual evapotranspiration of terrestrial ecosystems in China: Results from eddy covariance measurements 认领 引用 被引量：12
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作者 郑涵 于贵瑞 +11 位作者 王秋凤 朱先进 何洪林 王艳芬 张军辉 李英年 赵亮 赵风华 石培礼 王辉民 闫俊华 张一平 《Journal of Geographical Sciences》 SCIE CSCD 2016年第10期1391-1411,共21页
Understanding the spatial variation in annual actual evapotranspiration （AET） and its influencing factors is crucial for a better understanding of hydrological processes and water resources management. By synthesizi... Understanding the spatial variation in annual actual evapotranspiration （AET） and its influencing factors is crucial for a better understanding of hydrological processes and water resources management. By synthesizing ecosystem-level observations of eddy-covariance flux sites in China （a total of 61 sites）, we constructed the most complete AET dataset in China up to now. Based on this dataset, we quantified the statistic characteristics of AET and water budgets （defined as the ratio of AET to annual mean precipitation （MAP）, AET/MAP） of terrestrial ecosystems in China. Results showed that AET differed significantly among both different vegetation types and climate types in China, with overall mean AET of 534.7＋232.8 mm yr1. AET/MAP also differed significantly among different climate types, but there were no distinct differences in AET/MAP values across vegetation types, with mean AET/MAP of 0.82＋0.28 for non-irrigated ecosystems. We further investigated how the main climatic factors and vegetation attributes control the spatial variation in AET. Our findings revealed that the spatial variation of AET in China was closely correlated with the geographical patterns of climate and vegetation, in which the effects of total annual net radiation （Ro）, MAP and mean annual air temperature （MAT） were dominant. Thus, we proposed an empirical equation to describe the spatial patterns of AET in China, which could explain about 84% of the spatial variation in AET of terrestrial ecosystems in China. Based on the constructed dataset, we also evaluated the uncertainties of five published global evapotranspiration products in simulating site-specific AET in China. Results showed that large biases in site-specific AET values existed for all five global evapotranspiration products, which indicated that it is necessary to involve more observation data of China in their parameterization or validation, while our AET dataset would provide a data source for it. 展开更多
关键词 evapotranspiration water budget spatial variation eddy covariance terrestrial ecosystem China-FLUX
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Temporal and spatial variations of δ^18O in precipitation of the Yarlung Zangbo River Basin 认领 引用 被引量：9
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作者 LIU Zhongfang TIAN Lide +3 位作者 YAO Tandong GONG Tongliang YIN Changliang YU Wusheng 《Journal of Geographical Sciences》 SCIE 2007年第3期317-326,共10页
This paper reveals the temporal and spatial variations of stable isotope in precipitation of the Yarlung Zangbo River Basin based on the variations of δ^18O in precipitation at four stations （Lhaze, Nugesha, Yangcun... This paper reveals the temporal and spatial variations of stable isotope in precipitation of the Yarlung Zangbo River Basin based on the variations of δ^18O in precipitation at four stations （Lhaze, Nugesha, Yangcun and Nuxia） in 2005. The results show that δ^18O of precipitation has distinct seasonal changes in the Yarlung Zangbo River Basin. The higher value of δ^18O occurs in spring prior to monsoon precipitation, and the lower value occurs during monsoon precipitation. From the spatial variations, with the altitude-effect and rainout process during moisture transport along the Yarlung Zangbo River Valley, δ^18O of precipitation is gradually depleted. Thus, δ^18O of precipitation decreases gradually from the downstream to the upstream, and the lapse rate of δ^18O in precipitation is approximately 0.34‰/100m and 0.7%J‰/100km for the two reasons. During monsoon precipitation, spatial variation of δ^18O in precipitation is dominated by the amount effect in the large scale synoptic condition. 展开更多
关键词 Yarlung Zangbo River Basin δ^18O precipitation temporal and spatial variations
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Chemometric study of spatial variations of environmental and ecological characteristics in the Zhujiang River (Pearl River) Estuary and adjacent waters 认领 引用 被引量：6
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作者 SONG Xingyu HUANG Liangmin +4 位作者 ZHANG Jianlin YIN Kedong LIU Sheng TAN Yehui YIN Jianqiang 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2011年第4期60-74,共15页
Chemometric approach based on principal component analysis（PCA） was utilized to examine the spatial variances of environmental and ecological characteristics in the Zhujiang River（Pearl River） Estuary and adjacent... Chemometric approach based on principal component analysis（PCA） was utilized to examine the spatial variances of environmental and ecological characteristics in the Zhujiang River（Pearl River） Estuary and adjacent waters（ZREAW） in the South China Sea. The PCA result shows that the ZREAW can be divided into different zones according to the principal components and geographical locations of the study stations,and indicates that there are distinct regional variances on environmental features and the corresponding phytoplankton biomass and community structures among different areas. The spatial distribution of ecological features was implied to be influenced by various degrees of the different water resources,such as the Pearl River discharges,the coastal current and the oceanic water from the South China Sea. The variation of the biomass maximum zone and the complex impacts on the spatial distributions of phytoplankton biomass and production were also evaluated. 展开更多
关键词 principal component analysis spatial variations environmental conditions ecological distribution phytoplankton Zhujiang River （Pearl River） Estuary
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Spatial variation and driving mechanism of soil organic carbon components in the alluvial/sedimentary zone of the Yellow River 认领 引用 被引量：5
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作者 LI Guodong ZHANG Junhua +3 位作者 ZHU Lianqi TIAN Huiwen SHI Jiaqi REN Xiaojuan 《Journal of Geographical Sciences》 SCIE CSCD 2021年第4期535-550,共16页
Alluviation and sedimentation of the Yellow River are important factors influencing the surface soil structure and organic carbon content in its lower reaches.Selecting Kaifeng and Zhoukou as typical cases of the Yell... Alluviation and sedimentation of the Yellow River are important factors influencing the surface soil structure and organic carbon content in its lower reaches.Selecting Kaifeng and Zhoukou as typical cases of the Yellow River flooding area,the field survey,soil sample collection,laboratory experiment and Geographic Information System(GIS)spatial analysis methods were applied to study the spatial distribution characteristics and change mechanism of organic carbon components at different soil depths.The results revealed that the soil total organic carbon(TOC),active organic carbon(AOC)and nonactive organic carbon(NOC)contents ranged from 0.05–30.03 g/kg,0.01–8.86 g/kg and 0.02–23.36 g/kg,respectively.The TOC,AOC and NOC contents in the surface soil layer were obviously higher than those in the lower soil layer,and the sequence of the content and change range within a single layer was TOC>NOC>AOC.Geostatistical analysis indicated that the TOC,AOC and NOC contents were commonly influenced by structural and random factors,and the influence magnitudes of these two factors were similar.The overall spatial trends of TOC,AOC and NOC remained relatively consistent from the 0–20 cm layer to the 20–100 cm layer,and the transition between high-and low-value areas was obvious,while the spatial variance was high.The AOC and NOC contents and spatial distribution better reflected TOC spatial variation and carbon accumulation areas.The distribution and depth of the sediment,agricultural land-use type,cropping system,fertilization method,tillage process and cultivation history were the main factors impacting the spatial variation in the soil organic carbon(SOC)components.Therefore,increasing the organic matter content,straw return,applying organic manure,adding exogenous particulate matter and conservation tillage are effective measures to improve the soil quality and attain sustainable agricultural development in the alluvial/sedimentary zone of the Yellow River. 展开更多
关键词 soil organic carbon Yellow River sediment spatial variation driving mechanism cultivation history
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Spatial variation law of vertical derivative zero points for potential field data 认领 引用 被引量：18
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作者 王万银 张功成 梁建设 《Applied Geophysics》 SCIE 2010年第3期197-209,292,共13页
In this paper we deduce the analytic solutions of the first- and second-order vertical derivative zero points for gravity anomalies in simple regular models with single, double, and multiple edges and analyze their sp... In this paper we deduce the analytic solutions of the first- and second-order vertical derivative zero points for gravity anomalies in simple regular models with single, double, and multiple edges and analyze their spatial variation. For another simple regular models where it is difficult to obtain the analytic expression of the zero point, we try to use the profile zero points to analyze the spatial variation. The test results show that the spatial variation laws of both first- and second-order vertical derivative zero points are almost the same but the second-order derivative zero point position is closer to the top surface edge of the geological bodies than the first-order vertical derivative and has a relatively high resolution. Moreover, with an increase in buried depth, for a single boundary model, the vertical derivative zero point location tends to move from the top surface edge to the outside of the buried body but finally converges to a fixed value. For a double boundary model, the vertical derivative zero point location tends to migrate from the top surface edge to the outside of the buried body. For multiple boundary models, the vertical derivative zero point location converges from the top surface edge to the outside of the buried body where some zero points coincide and finally vanish. Finally, the effectiveness and reliability of the proposed method is verified using real field data. 展开更多
关键词 vertical derivative zero point spatial variation law edge location
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Spatial variation and prediction of forest biomass in a heterogeneous landscape 认领 引用 被引量：6
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作者 S. Lamsal D. M. Rizzo R. K. Meentemeyer 《Journal of Forestry Research》 CAS CSCD 2012年第1期13-22,共10页
Large areas assessments of forest bioinass distribution are a challenge in heterogeneous landscapes, where variations in tree growth and species composition occur over short distances. In this study, we use statistica... Large areas assessments of forest bioinass distribution are a challenge in heterogeneous landscapes, where variations in tree growth and species composition occur over short distances. In this study, we use statistical and geospatial modeling on densely sample.d forest biomass data to analyze the relative importance of ecological and physiographic variables as determinants of spatial variation of forest biomass in the environmentally heterogeneous region of the Big Sur, California. We estimated biomass in 280 forest Plots （one plot per 2.85 km2） and meas- ured an array of ecological （vegetation community type, distance to edge, amount of surrounding non-forest vegetation, soil properties, fire history） and physiographic drivers （elevation, potential soil moisture and solar radiation, proximity to the coast） of tree growth at each plot location. Our geostatistical analyses revealed that biomass distribution is spatially structured and autocorrelated up to 3.1 kin. Regression tree （RT） models showed that both physiographic and ecological factors influenced bio- mass distribution. Across randomly selected sample densities （sample size 112 to 280）, ecological effects of vegetation community type and distance to forest edge, and physiographic effects of elevation, potential soil moisture and solar radiation were the most consistent predictors of biomass. Topographic moisture index and potential solar radiation had apositive effect on biomass, indicating the importance of topographically- mediated energy and moisture on plant growth and biomass accumula- tion. RT model explained 35% of the variation in biomass and spatially autocorrelated variation were retained in regession residuals. Regression kriging model, developed from RT combined with kriging of regression residuals, was used to map biomass across the Big Sur. This study dem- onstrates how statistical and geospatial modeling can be used to dis- criminate the relative importance of physiographic and ecologic effects on forest biomass and develop spatial models to predict and map biomass distribution across a heterogeneous landscape. 展开更多
关键词 forest biomass landscape heterogeneity spatial variation semivariogram regression tree regression kriging Big Sur California
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Effects of spatial variation in cohesion over the concrete-rock interface on dam sliding stability 认领 引用 被引量：6
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作者 Alexandra Krounis Fredrik Johansson Stefan Larsson 《Journal of Rock Mechanics and Geotechnical Engineering》 CSCD 2015年第6期659-667,共9页
The limit equilibrium method （LEM） is widely used for sliding stability evaluation of concrete gravitydams. Failure is then commonly assumed to occur along the entire sliding surface simultaneously.However, the brit... The limit equilibrium method （LEM） is widely used for sliding stability evaluation of concrete gravitydams. Failure is then commonly assumed to occur along the entire sliding surface simultaneously.However, the brittle behaviour of bonded concrete-rock contacts, in combination with the varying stressover the interface, implies that the failure of bonded dam-foundation interfaces occurs progressively. Inaddition, the spatial variation in cohesion may introduce weak spots where failure can be initiated.Nonetheless, the combined effect of brittle failure and spatial variation in cohesion on the overall shearstrength of the interface has not been studied previously. In this paper, numerical analyses are used toinvestigate the effect of brittle failure in combination with spatial variation in cohesion that is taken intoaccount by random fields with different correlation lengths. The study concludes that a possible existenceof weak spots along the interface has to be considered since it significantly reduces the overallshear strength of the interface, and implications for doing so are discussed. 展开更多
关键词 Concrete gravity dam Sliding stability Cohesion Brittle failure Spatial variation
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Spatial variation of reference crop evapotranspiration on Tibetan Plateau 认领 引用 被引量：5
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作者 Yong-hong YANG Zhan-yu ZHANG Xin-yi XIANG 《Water Science and Engineering》 CAS 2009年第1期112-120,共9页
This study is based on meteorological observation data collected at 38 weather stations on the Tibetan Plateau over several decades. Daily reference crop evapotranspiration （ETo） was calculated with the FAO-56 stand... This study is based on meteorological observation data collected at 38 weather stations on the Tibetan Plateau over several decades. Daily reference crop evapotranspiration （ETo） was calculated with the FAO-56 standard Penman-Monteith formula. A test of normality was performed with Statistica 6.0 software, isotropic and anisotropic semi-variogram analysis was conducted with the GS＋ （geostatistics for the environmental sciences） system for Windows 7.0, and the characteristics of spatial variation of daily ETo were obtained. The following results can be obtained Daily ETo for different periods on the Tibetan Plateau are distributed normally; Except for daily ETo in the E-W （east-west） direction in the summer, which showed a slight negative correlation with distance change, the Moran＇s indexes of daily ETo for different periods in all directions on the Tibetan Plateau within a 100-km distance were positive, demonstrating a positive correlation with distance change; Variograms of daily ETo in June, the dry season, the wet season, as well as annual average daily ETo fit well with the Gaussian model; A variogram of daily ETo in December fit well with the exponential model; Variograms of daily ETo for the four seasons fit well with the linear With sill model. 展开更多
关键词 reference crop evapotranspiration Penman-Monteith formula semi-variogram spatial variation tibetan Plateau
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Influence of groundwater level change on vegetation coverage and their spatial variation in arid regions 认领 引用 被引量：16
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作者 苏里坦 宋郁东 玛丽娜 《Journal of Geographical Sciences》 2004年第3期323-329,共7页
Sampling and testing are conducted on groundwater depth and vegetation coverage in the 670 km2 of the Sangong River Basin and semi-variance function analysis is made afterwards on the data obtained by the application ... Sampling and testing are conducted on groundwater depth and vegetation coverage in the 670 km2 of the Sangong River Basin and semi-variance function analysis is made afterwards on the data obtained by the application of geo-statistics. Results showed that the variance curve of the groundwater depth and vegetation coverage displays an exponential model. Analysis of sampling data in 2003 indicates that the groundwater depth and vegetation coverage change similarly in space in this area. The Sangong River Basin is composed of upper oasis, middle ecotone and lower sand dune. In oasis and ecotone, influenced by irrigation of the adjoining oasis, groundwater level has been raised and soil water content also increased compared with sand dune nearby, vegetation developed well. But in the lower reaches of the Sangong River Basin, because of descending of groundwater level, soil water content decreased and vegetation degenerated. From oasis to abandoned land and desert grassland, vegetation coverage and groundwater level changed greatly with significant difference respectively in spatial variation. Distinct but similar spatial variability exists among the groundwater depth and vegetation coverage in the study area, namely, the vegetation coverage decreasing (increasing) as the groundwater depth increases (decreases). This illustrates the great dependence of vegetation coverage on groundwater depth in arid regions and further implies that among the great number of factors affecting vegetation coverage in arid regions, groundwater depth turns out to be the most determinant one. 展开更多
关键词 geo-statistics groundwater level groundwater depth arid regions vegetation coverage semi-variance function spatial variation kriging
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Spatial Variation of Dissolved Organic Carbon in Soils of Riparian Wetlands and Responses to Hydro-geomorphologic Changes in Sanjiang Plain, China 认领 引用 被引量：7
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作者 XI Min KONG Fanlong +2 位作者 LYU Xianguo JIANG Ming LI Yue 《Chinese Geographical Science》 SCIE CSCD 2015年第2期174-183,共10页
Spatial variation of dissolved organic carbon(DOC) in soils of riparian wetlands and responses to hydro-geomorphologic changes in the Sanjiang Plain were analyzed through in situ collecting soil samples in the Naoli R... Spatial variation of dissolved organic carbon(DOC) in soils of riparian wetlands and responses to hydro-geomorphologic changes in the Sanjiang Plain were analyzed through in situ collecting soil samples in the Naoli River and the Bielahong River. The results showed that the average contents of DOC for soil layer of 0–100 cm were 730.6 mg/kg, 250.9 mg/kg, 423.0 mg/kg and 333.1 mg/kg respectively from riverbed to river terrace along the transverse directions of the Naoli watershed. The content of the soil DOC was the highest in the riverbed, lower in the high floodplain and much lower in the river terrace, and it was the lowest in the low floodplain. The difference in the content and vertical distribution of DOC between the riverbed and the three riparian wetlands was significant, while it was not significant among the low floodplain, the high floodplain and the river terrace. The variability of soil DOC was related to the hydrological connectivity between different landscape position of the riparian wetlands and the adjacent stream. Extremely significant correlations were observed between DOC and total organic carbon(TOC), total iron(TFe), ferrous iron(Fe(II)) whose correlation coefficients were 0.819, –0.544 and –0.709 in riparian wetlands of the Naoli River. With the increase of wetland destruction, soil p H increased and soil DOC content changed. The correlation coefficients between soil DOC and TOC, TFe, Fe(II) also changed into 0.759, –0.686 and –0.575 respectively in the Bielahong River. Under the impact of drainage ditches, the correlations between soil DOC and TFe, Fe(II) were not obvious, while the soil p H was weakly alkaline and was negatively correlated with soil DOC in the previous high floodplain. It indicates that riparian hydro-geomorphology is the main factor that could well explain this spatial variability of soil DOC, and the agricultural environmental hydraulic works like ditching also must be considered. 展开更多
关键词 dissolved organic carbon（DOC） riparian wetlands spatial variation hydro-geomorphologic changes Sanjiang Plain
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Spatial variation of technical efficiency of cereal production in China at the farm level 认领 引用 被引量：1
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作者 ZHOU Wen-bin WANG Huai-yu +1 位作者 HU Xi DUAN Feng-ying 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2021年第2期470-481,共12页
Rice, wheat and maize are the main staple food crops to ensure the food security in China with diversified climate condition, cropping system and environmental and socio-economic factors across provinces. Spatial vari... Rice, wheat and maize are the main staple food crops to ensure the food security in China with diversified climate condition, cropping system and environmental and socio-economic factors across provinces. Spatial variation of technical efficiency in farmers' field is helpful to understand the potential to improve farmers' yield given the inputs level and reduce the yield gap. The study is based on a large-scale farm household survey which covered 1 218 rice farmers, 3 566 wheat farmers and 2 111 maize farmers in the main producing areas. The results indicate that rice farmers are with very high technical efficiency level, nearly 0.9 on average, with little room to improve the efficiency of agricultural inputs. Similar results have been found in wheat and maize farmers' fields, although the technical efficiency levels are lower than that of rice farmers while still at a high level with obvious variation across regions. Farmers with higher yield level also achieve better technical efficiency in most locations. Both local environmental and socio-economic factors significantly affect farmers' technical efficiency. In the context of urbanization and economic development, improved and new agricultural technologies need to be prioritized and facilitated to improve cereal yield at farm level. 展开更多
关键词 technical efficiency spatial variation rice wheat maize
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Temporal and spatial variations of the Huanghe River mouth bars 认领 引用 被引量：1
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作者 YANGZuosheng ZHANGYong +2 位作者 LIUZhan WEIHelong HEShufeng 《Acta Oceanologica Sinica》 SCIE CAS 2005年第2期43-56,共14页
On the basis of the bathymetric records of 371 survey sections in the present Huanghe mouth area from 1996 to 2001, the temporal and spatial variations of the Huanghe mouth bars were studied by using GIS technology. T... On the basis of the bathymetric records of 371 survey sections in the present Huanghe mouth area from 1996 to 2001, the temporal and spatial variations of the Huanghe mouth bars were studied by using GIS technology. The variation of the mouth bars is closely related to the water and sediment discharges from the Huanghe River to the sea that has been decreasing drastically in recent years, and to coastal hydrodynamic regimes. The characteristics of the mouth bars are unique in contrast with those of other estuaries in the world. (1) The mouth bars of the Huanghe River consist of many small sandbars. Usually the sandbars are of ellipse-shape with the long axis of about 1~6 km, and short axis of about 1~4 km. The long axis is parallel to the principal direction of tidal current, and the short axis is variable, depending on the local dynamics. The crest of the sandbars is only about 0.4 m below the water surface at low tide. They are distributed within an area of 20 km2, not far from the river mouth area. The present mouth bars are in small-medium size, quite different from the large one formed during the 1970s and 1980s, when the river sediment discharge was several times larger than that after 1996. (2) The scale of a river mouth bar is related to the river discharge of that year. In 1997 sediment discharge from the Huanghe River was 42 Mt, and the mouth bar consisted of several small scattered sandbars. In 1998 the size of mouth bars was much larger than that in 1997, as the sediment discharge from the Huanghe River increased to 363 Mt. Variation of the mouth bars largely depends on the sediment discharge with a correlation coefficient of 0.78. The calculation of the volume of the mouth bar area shows that about 30%~40% of the river's into-sea sediment is deposited in the mouth bar area. (3) Compared with other large estuaries in the world, the Huanghe mouth bars have three unique features in responding to its high sediment concentration: small size, steep slope gradient and shallow crest depth. 展开更多
关键词 Huanghe mouth bars temporal and spatial variations mechanism of formation
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Temporal and Spatial Variation Characteristics of Precipitation during Crop Growing Season in Northeast China 认领 引用 被引量：2
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作者 李秀芬 李帅 +2 位作者 纪瑞鹏 郭春明 姜丽霞 《Agricultural Science & Technology》 CAS 2010年第6期137-140,168,共4页
[Objective] The aims were to understand variation characteristics of water resources and provide theoretical guidance for the formulation of agricultural irrigation methods.[Method] Taking the precipitation records du... [Objective] The aims were to understand variation characteristics of water resources and provide theoretical guidance for the formulation of agricultural irrigation methods.[Method] Taking the precipitation records during crop growing season（from April to September）observed by 177 weather stations from 1971 to 2008 in the three provinces of Northeast China（Heilongjiang,Jilin and Liaoning）as research data,annual change and spatial distribution characteristics of precipitation during crop growing season were analyzed by means of small grid interpolation and climatic trend rate.[Result] The precipitation during crop growing season general exhibited the decreasing trend and the precipitation trend rate was-8.6 mm/10a in Northeast China.In addition,there was lack of rain from 1971 to 1980 and relatively abundant of rain during 1981 and 1990 respectively.Moreover,the precipitation obviously exhibited decreasing trend from 1991 to 2008.But the decreasing trend was inconsistent in spatial distributions,that was,the precipitation slightly increased in relatively rainless areas and obviously decreased in relatively rainy areas.[Conclusion] The areas with obvious decreasing trend of precipitation during crop growing season are the main grain producing zones in Northeast China,so the problem of food production security caused by the precipitation changes should be paid enough attention. 展开更多
关键词 Regions in the Northeast China Precipitation during crop growing season Temporal and spatial Variations
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Analysis on temporal and spatial variations of groundwater hydrochemical characteristics in the past decade in southern plain of Beijing, China 认领 引用 被引量：1
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作者 JIANG Ti-sheng QU Ci-xiao +3 位作者 WANG Ming-yu SUN Yan-wei HU Bo CHU Jun-yao 《Journal of Groundwater Science and Engineering》 2017年第3期235-248,共14页
Groundwater utilization and protection are crucial for sustainable urban development. This is especially true for Beijing, where groundwater is an important source for urban water supply. In this study, statistical me... Groundwater utilization and protection are crucial for sustainable urban development. This is especially true for Beijing, where groundwater is an important source for urban water supply. In this study, statistical methods, including descriptive statistics, correlation analysis, principal component analysis, and Piper-Tri-linear diagram, were used in analyzing the temporal and spatial variations of the hydrochemical characteristics of groundwater based on monitored data from the southern plain of Beijing, China. Results indicated consistent changes of groundwater's hydrochemical characteristics in different aquifers in the study area. The percentage of HCO_3^-in total anion increased significantly in the groundwater, and hydrochemical water type evolved gradually from Ca-Mg-Cl-SO_4 based to Ca-Mg-HCO_3 based from period 2005-2007 to period 2013-2015. In shallow groundwater, the concentration of Na^+, Ca2+, SO_42-, HCO_3^-, and total dissolved solids(TDS) increased from period 2005-2007 to period 2013-2015, and the greatest change came from HCO_3^-, rising from 428.93 to 528.96 mgL-1. The changes of main ionic concentrations in the deep groundwater were consistent with those in the shallow groundwater for both periods. However, the variations in deep groundwater were less than those in shallow groundwater. The temporal and spatial variations of hydrochemical characteristics reflect the groundwater quality in the study area. This study could facilitate decision-making process on the protection of groundwater resources to ensure its sustainable utilization. 展开更多
关键词 Beijing Groundwater Hydrochemical characteristics Temporal and spatial variation Water quality
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