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Hyperconcentrated flows as influenced by coupled wind-water processes

Science China Earth sciences 2005年第11期48卷 1990-2000页

作者： xu jiongxin institute of geographical sciences and natural resources research, Chinese Academy of sciences Key Laboratory of Water Cycle and Related Land Surface Processes, Chinese Academy of sciences, Beijing 100101, China Key Laboratory of Water Cycle and Related Land Surface Processes Chinese Academy of Sciences Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China

Using data from more than 40 rivers in the middle Yellow River basin, a study has been made of the influence of coupled wind-water processes on hyperconcentrated flows. A simple “vehicle” model has been proposed to describe hyperconcentrated flows. The liquid phase of two-phase flows is a “vehicle”, in which coarse sediment particles are carried as solid-phase. The formation and characteristics of hyperconcentrated flows are closely related with the forma-tion and characteristics of this liquid-phase and solid-phase. Surface materials and geomorphic agents of the middle Yellow River basin form some patterns of combination, which have deep influence on the formation and characteristics of liquid- and solid-phases of hyperconcentrated flows. The combination of high percentages of relatively coarse material with low percentages of fine material appears in the area predominated by the wind process, where the supply of rela-tively coarse sediment is sufficient, but the supply of relatively coarse sediment is not. The com-bination of low percentages of relatively coarse material with high percentages of fine material appears in the area predominated by the water process, where the supply of fine sediment is sufficient, but the supply of fine sediment is not. In the area predominated by coupled wind-water processes appears the combination of medium percentages of coarse and fine materials, and thus both coarse and fine sediments are in relatively sufficient supply. The manner in which the mean annual sediment concentrations of liquid- and solid-phases vary with total suspended sediment concentration is different. With the increased total suspended sediment concentration, mean annual sediment concentration of liquid-phase increased to a limit and then remained constant; however, mean annual sediment concentrations of solid-phase in-creased continuously. Thus, the magnitude of total suspended sediment concentration depends on the supply conditions of relatively coarse sedime

关键词： river sediment, hyperconcentrated flows, liquid-solid two-phase flows, wind process, fluvial process, Yellow River

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Modified conceptual model for predicting the tendency of alluvial channel adjustment induced by human activities

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Chinese Science Bulletin 2001年第S1期46卷 51-57页

作者： xu jiongxin{2. of {2. sciences and natural resources research, Chinese Academy of sciences, Beijing 100101, China (e-mail: xujxin?***) institute of geographical {2. and natural resources research Chinese Academy of Sciences Beijing China

After a discussion about some limitations of Schumm’s conceptual model for prediction of river metamorphosis, this study introduces the channel boundary material as an independent variable, and thereby establishes a conceptual model that can be used to predict the direction of channel adjustment induced by human activities. This model has been tested by data from natural rivers and a laboratory model river, and can be used to explain the complex behavior of channel adjustment after reservoir construction.

关键词： human influence on channels channel boundary condi- tions feedback in channel system prediction of channel adjustment.

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Optimization of mathematical models for thematic maps

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Science China(Technological sciences) 2010年第S1期53卷 15-24页

作者： QI QingWen1,ZHANG An1,JIANG LiLi1,ZOU XiuPing2.xu Li3 & CHENG Xi1,4 1 institute of {2. {2. and natural resources research,Chinese Academy of {2.,Beijing 100101,China 2.institute of Policy and Management,Chinese Academy of {2.,Beijing 100080,China 3 Taishan University,Taian 2.102.,China 4 Graduate University of Chinese Academy of {2.,Beijing 100049,China institute of geographical {2. and natural resources research Chinese Academy of Sciences Beijing China institute of Policy and Management Chinese Academy of Sciences Beijing China Taishan University Taian China Graduate University of Chinese Academy of sciences Beijing China

The thematic map is a major class of maps designed to demonstrate particular features or concepts,functioning as an indispensable tool in geographical *** process of thematic mapping is one into which geographical {2. goes deeply and *** key activity and course of thematic map production is the use of mathematical models to create thematic data ***,the selection and optimization of mathematical models is in the forefront of thematic map *** theoretical foundations,mechanisms and methods of mathematical model optimization are expounded in this paper,including two approaches,the phase by phase mode and the multi-aim scheme balance *** studies in eco-environment mapping and emergency mapping are described and analyzed,with a hierarchical analysis method being used in the model optimization for eco-environment fragility and sensitivity assessment mapping in Beibuwan (Guangxi) District,the dynamic system (DS) method being used in the model optimization for ecological security adjustment mapping in Xishuang Banna,Yunnan province,and the multi-phase mode being used in the models for forest fire and infectious diseases mapping.

关键词： thematic map mathematic model optimization

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Process and mechanism of arable land change in Hebei Province during the past 50 years

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Journal of geographical sciences 2001年第4期11卷 47-52页

作者： xu Yue-qing (institute of {2. {2. and natural resources research, CAS, Beijing 100101, China College of Resource and Environment Science, Hebei Normal University, Shijiazhuang 050016, China )

Hebei Province is one of the regions with most densely population, fastest economic growth and most intensive land use in China. The contradiction of land shortage sharpened by high-speed economic development with population growth has become a serious problem, which has restricted regional sustainable *** paper revealed the basic process, regional differences of change and the gravity center of arable land area according to the long-series statistical data of arable land during the past 50 years. On the basis of the above mentioned, the major driving forces that influence the changes of the arable land are discussed. The research results indicate that there is a trend of obvious fluctuating decrease in arable land area during the last 50 years. The changes of arable land area undergo the process from increase to sharp decrease to gently decrease. The regional disparity of change in arable land area is very notable and the gravity center of arable land area moves to the northeast 49.2. km. Regarding the decrease in arable land, the direct driving forces include adjustments of agricultural structure and reclamation, and indirect driving forces include advance in technology, economic interest and population growth etc.

关键词： decrease in arable land area changing process mechanism Hebei Province

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ANALYSIS ON LAND-USE CHANGE AND SOCIO-ECONOMIC DRIVING FACTORS IN H AINAN ISLAND DURING 50YEARS FROM 1950TO 1999

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Chinese geographical Science 2002年第3期 2-7页

作者： xu Xin-liang 1 ,ZENG Lan 2. ,ZHUANG Da-fang 1 (1.institute of {2. {2. and natural resources research,t he Chinese Academy of {2.,Beijing 100101,P.R.China 2.Information Consultative Center,institute of Macro-economy,Natio nal Planning institute of geographical {2. and natural resources research， the Chinese Academy of {2.， Beijing 100101， P.R. China Information Consultative Center， institute of Macro-economy， National Planning Committee， Beijing 10082.， P. R. China

Land-use change is an important part of global change research(IGBP,1990-1992..But the majority of researches focus on the {2. dr iving force of land use *** thi s paper,the authors studied the rela tionship be-tween socio-economic driving facto rs and land-use change with time series in Hainan *** on the stud y for the evolution of administrative system and policies in Hainan Island and the comprehensive analysis on the socia l economy da-ta and changes of social policies,th e socio-economic policies,human activities and land use of Hainan can be divided into three periods with different ch aracters:period from1950to 1978ch aracterized by the planning economi c system,peri-od from 1978to 1988characterized by the transfer of economic system and a doption of open policy,new stage fro m 1988to 1998with high growing *** th e other hand the authors describe the character of the periods and land-use change process affected by socio-economic *** paper provides an important method for evaluating the development and changes of Hainan social economy dur ing the 50years from 1950to 1999and f orecasting the development of Hainan so-cial economy in future.

关键词： socio-economic development land-use change planning economy refo rmand open-up economic sys-tem

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A study of scale effect on specific sediment yield in the Loess Plateau,China

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Science China Earth sciences 2007年第1期50卷 102-112页

作者： YAN YunXia & xu jiongxin institute of geographical sciences and natural resources research, Chinese Academy of sciences Key Laboratory of Water Cycle and Related Land Surface Processes, Chinese Academy of sciences, Beijing 100101, China institute of geographical {2. and natural resources research Chinese Academy of Sciences Key Laboratory of Water Cycle and Related Land Surface Processes Chinese Academy of Sciences Beijing 100101 China

Based on data from 148 hydrometric stations in the Yellow River Basin, an analysis of regional scale relationship, or the relationship between specific sediment yield and drainage basin area, has been undertaken in the study area of the Loess Plateau. For different regions, scale relationship in log-log ordinate can be fitted by two types of lines: straight and parabola, and for each line, a function was fitted using regression analysis. The different scale relationships have been explained in terms of the difference in surface material distribution and landforms. To offset the scale-induced influence, calcu-lation has been done based on the fitted functions, in order to adjust the data of specific sediment yield to a common standard area. Based on the scaled data, a map of specific sediment yield was con-structed using Kriging interpolation. For comparison, a map based on the un-scaled data of specific sediment yield was also constructed using the same method. The two maps show that the basic pattern of specific sediment yield was basically the same. The severely eroded areas (Ys >10000 t km-2.-1) were at the same locations from Hekouzhen to Longmen in the middle Yellow River Basin. However, after the adjustment to a common standard area, the very severely eroded area (Ys >2.000 t km-2.-1) became much enlarged because after the adjustment, all the values of Ys in the lower river basin in those regions became much larger than before.

关键词： Loess Plateau erosion scale effect specific sediment yield.

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GIS and ANN model for landslide susceptibility mapping

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Journal of geographical sciences 2001年第3期11卷 374-381页

作者： xu Zeng-wang (State Key Laboratory of resources and Environment Information System, {2. of Geographic {2. and natural resources research, CAS, Beijing 100101, China) State Key Laboratory of resources and Environment Information System Institute of Geographic Sciences and Natural Resources Research CAS

Landslide hazard is as the probability of occurrence of a potentially damaging landslide phenomenon within specified period of time and within a given area. The susceptibility map provides the relative spatial probability of landslides occurrence. A study is presented of the application of GIS and artificial neural network model to landslide susceptibility mapping, with particular reference to landslides on natural terrain in this paper. The method has been applied to Lantau Island, the largest outlying island within the territory of Hong Kong. A three-level neural network model was constructed and trained by the back-propagate algorithm in the geographical database of the study area. The data in the database includes digital elevation modal and its derivatives, landslides distribution and their attributes, superficial geological maps, vegetation cover, the raingauges distribution and their 14 years 5-minute observation. Based on field inspection and analysis of correlation between terrain variables and landslides frequency, lithology, vegetation cover, slope gradient, slope aspect, slope curvature, elevation, the characteristic value, the rainstorms corresponding to the landslide, and distance to drainage Une are considered to be related to landslide susceptibility in this study. The artificial neural network is then coupled with the ArcView3.2.GIS software to produce the landslide susceptibility map, which classifies the susceptibility into three levels: low, moderate, and high. The results from this study indicate that GIS coupled with artificial neural network model is a flexible and powerful approach to identify the spatial probability of hazards.

关键词： GIS artificial neural network model landslide susceptibility mapping

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长江上游干支流近期水沙变化及其与水库修建的关系

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山地学报 2009年第4期27卷 385-393页

作者：许炯心中国科学院地理科学与资源研究所中国科学院水循环与地表过程重点实验室

基于水文站实测的长系列水沙资料,运用统计方法研究了长江上游干支流的近期水沙变化。屏山站年输沙量的变化自1999年以后开始减小,扭转了1980～1998年的增加趋势。高场站年输沙量由1990～2.00年的减小趋势,变化为2.00～2.07年的增大趋... 详细信息

基于水文站实测的长系列水沙资料,运用统计方法研究了长江上游干支流的近期水沙变化。屏山站年输沙量的变化自1999年以后开始减小,扭转了1980～1998年的增加趋势。高场站年输沙量由1990～2.00年的减小趋势,变化为2.00～2.07年的增大趋势。北碚站的年输沙量呈进一步减少的趋势。武隆站年输沙量改变了1990～2.00年的增加趋势,2.00～2.07年显著减小。宜昌站的年输沙量延续了从2.世纪80年代中期以来的减少趋势,2.02.2.07年急剧减小。采用输沙量-径流量双累积曲线方法进行了分析,发现各站双累积曲线上最近一次转折点的出现,均与水库的修建有关。基于双累积曲线估算了近期各站的减沙量(或增沙量)。研究还发现,近期屏山、北碚、武隆、宜昌4站含沙量均呈现减小趋势,与水库的拦沙作用密切相关。但是,岷江近期水电梯级开发的大规模展开,巨量弃土、弃渣进入河道,导致了2.02.2.07年间含沙量的增大。建立了宜昌站年输沙量与长江上游流域内累计水库库容量及宜昌站年径流量之间的回归方程,估算出它们对于长江上游产沙量变化的贡献率分别为71.4%和2..6%。这表明,水库拦沙是导致长江上游产沙量减小的主要原因。

关键词：水沙变化水库双累积曲线长江上游

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Sediment transferring function of the lower reaches of the Yellow River influenced by drainage basin factors and human activities

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Science China Earth sciences 2005年第12期48卷 2194-2202页

作者： xu jiongxin institute of geographical {2. and natural resources research ChineseAcademy of Sciences Beijing 100101 China

Sediment transferring function (Fs) of rivers is defined and indexed in this study, based on the concept of sediment budget at river reach scales. Then, study is made on the Fs of the lower reaches of the Yellow River in relation to natural and human factors in the drainage basin, such as the annual precipitation in different water and sediment source areas, proportion of >0.05 mm sediment of the total sediment load to the lower reaches of Yellow River, the regu-lated degree of the “clear” baseflow from the drainage area above Lanzhou, frequency of hy-perconcentrated flows, area of soil and water conservation measures in the drainage basin. As a result, a multiple regression equation has been established between Fs and 7 influencing factors, with multiple correlation coefficient r = 0.90. The reduction in annual precipitation in different water and sediment source areas has different effects on Fs. The reduction in annual precipitation in the area above Hekou Town and the area between Longmen and Sanmenxia results in a reduction in Fs, but the reduction in annual pre-cipitation in the area between Hekou Town and Longmen results in an increase in Fs. The grain size composition of sediment load strongly affects the Fs; the larger the proportion of >0.05 mm sediment in the suspended sediment load entering the lower reaches of the Yellow River is, the lower the Fs will be. Thus, if the Xiaolangdi Reservoir traps coarse sediment and releases fine sediment, Fs will be enhanced. This study also shows that the lower the proportion of high-flow season river flow to the annual total river flow at Lanzhou Station is, the lower the Fs will be. Therefore, the interception of large quantities of clear water by the reservoirs on the upper reaches of Yellow River is one of the major causes for the decrease in Fs in the lower reaches of the Yellow River.

关键词： river sediment, channel sedimentation, drainage basin factors, human activities, Yellow River.

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Evaluation of suitability,adaptability,and reserve potential of construction land on the Qinghai-Tibet Plateau

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Journal of geographical sciences 2024年第1期34卷 41-61页

作者： YANG Hua xu Yong ZHOU Kan WANG Lijia xu Lin Key Laboratory of Regional Sustainable Development Modeling Institute of Geographic Sciences and Natural Resources ResearchCASBeijing 100101China University of Chinese Academy of sciences Beijing 100049China

Construction land is the leading carrier of human activities such as production and *** the construction land suitability(CLS)on the Qinghai-Tibet Plateau(QTP)holds significant implications for harmonizing the relationship between ecological protection and human activity and promoting population and industry layout ***,no relevant studies provide a complete CLS assessment of the *** this study,we developed a model-based CLS evaluation framework coupling of pattern and process to calculate the global CLS on the QTP based on a previously developed CLS evaluation ***,using the land-use data of 1990,2.00,2.10,and 2.2.,we examined the adaptability of existing construction land(ECL)to the CLS assessment result through the adaptability index and vertical gradient index and further analyzed the limitations of maladaptive construction ***,we calculated the potential area of reserve suitable construction *** article includes four conclusions:(1)The highly suitable,suitable,moderately suitable,marginally suitable,and unsuitable CLS classes cover areas of 0.33×10^(4)km^(2.,10.42.10^(4)km^(2.,18.06×10^(4)km^(2.,2..12.10^(4)km^(2.,and 2.5.2.×10^(4)km^(2.,*** approximately 11%of the study area on the QTP is suitable for large-scale permanent construction land,and approximately 79.50%of the area is unsuitable under current economic and technological conditions.(2.The ECL adaptability index is 85.16%,85.93%,85.18%,and 78.01%during 1990–2.2.,respectively,with an average adaptability index exceeding 80%on the *** ECL distribution generally conforms to construction land suitable space characteristics but with a significant spatial difference.(3)From 1990 to 2.2.,the maladaptive ECL was dominated by rural settlement land,transport land,and special land,with a rapidly increasing proportion of urban and other construction *** maladaptive ECL is constrained by both elevation and slope in the southern Qinghai Pla

关键词： land resource construction land suitability existing construction land adaptability human activity Qinghai-Tibet Plateau

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