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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 {2. of {3. 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 1. 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 100101 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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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. sciences and Natural resources research,chinese academy of sciences,Beijing 100101,China 2.institute of Policy and Management,chinese academy of sciences,Beijing 100080,China 3.Taishan University,Taian 2.102.,China 4 Graduate University of chinese academy of sciences,Beijing 100049,China chinese Acad Sci Inst Geog Sci & Nat Resources Res Beijing 100101 Peoples R China chinese Acad Sci Inst Policy & Management Beijing 100080 Peoples R China Taishan Univ Tai An 271021 Shandong Peoples R China chinese Acad Sci Grad Univ Beijing 100049 Peoples R 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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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 {3. sciences and Natural resources research, chinese academy of sciences, Beijing 100101, China (e-mail: xujxin?***) 1. institute of geographical {2. and Natural {3. research Chinese Academy of Sciences 100101 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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COMPLICATED FILL-SCOURBEHAVIORS OF THE YELLOW RIVER ANDTHE CHANNEL-FORMING PROCESSES

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International Journal of Sediment research 1999年第2期14卷 259-266页

作者： xu jiongxin (1 {2. of Geography,{3., Beijing 100101, China)

Based on the data from 159 events at the Tongguan station on the Yellow River, we have found the rule to describe the complicated relationship between the fill-scour features and the event-maximum suspended concentration (C_max). The depth of scour is large if the C_max is low. and is small if C_max is high. However, if C_max increases to the ranges of hyperconcentrated flows, scour occurs again. Controlled by the foregoing complicated fill-scour behaviors, the channel adjustment of the Yellow River is also complicated. When the suspended concentration is low, channel scour occurs, and thereby the channel shape tends to be narrower and deeper, and the thalweg more sinuous. When the suspended concentration increases, channel fill occurs, leading to an increase in the channel width-depth ratio and a decrease in the channel sinuosity. However, when the suspended concentration further increases and exceeds a certain threshold, channel scour occurs again, and the adjustment of channel morphology turns to the opposite direction. The rules outlined in the paper for the channel adjustment of the lower Yellow River may provide a new thinking for the regulation of the channel morphology of the lower Yellow River after the closure of the Xiaolangdi Dam, through the regulation of the lower Yellow River’s water and sediment by choosing some specific operation modes of the reservoir Either by releasing clear water or by releasing man-made hyperconcentrated flows, the downstream channel may tend to be narrowed, deeper and more sinuous.

关键词： Channel adjustment Fill-scour behavior Hyperconcentrated flows Lower Yellow River

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Quantitative estimation of the shrub canopy LAI from atmosphere-corrected HJ-1 CCD data in Mu Us Sandland

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Science China Earth sciences 2010年第S1期53卷 26-33页

作者： CHEN Wei1,2.CAO ChunXiang1,HE QiSheng1,2.GUO HuaDong3.ZHANG Hao1,2.LI RenQiang4,ZHENG Sheng1,2.xu Min1,2.GAO Mengxu1,2.ZHAO Jian1,2.LI Sha1,NI XiLiang1,2.JIA HuiCong1,JI Wei1,TIAN Rong1,2.LIU Cheng1,2.ZHAO YuXing5 & LI JingLu6 1 State Key Laboratory of Remote Sensing Science,Jointly Sponsored by the {2. of Remote Sensing Applications of{13. and Beijing Normal University,Beijing 100101,China 2.Graduate University of{13.,Beijing 100049,China 3.Center for Earth Observation and Digital Earth,chinese academy of sciences,Beijing 100190,China 4 China Key Laboratory of Ecological Network Observation and Modeling,{2. of geographical sciences and Natural resources {12.,chinese academy of sciences,Beijing 100101,China 5 Ordos Forestry Sand Control Science {2.,Dongsheng 017000,China 6 Inner Mongolia Biomass Thermoelectricity Limited Company,Wushen 0173.0,China 1. State Key Laboratory of Remote Sensing Science Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University Beijing 100101 China 2. Graduate University of chinese academy of sciences Beijing 100049 China 3. Center for Earth Observation and Digital Earth Chinese Academy of Sciences Beijing 100190 China 4. China Key Laboratory of Ecological Network Observation and Modeling Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China 5. Ordos Forestry Sand Control Science institute Dongsheng 017000 China 6. Inner Mongolia Biomass Thermoelectricity Limited Company Wushen 017300 China

The leaf area index(LAI) is an important ecological parameter that characterizes the interface between vegetation canopy and the *** addition,it is used by most process-oriented ecosystem *** paper investigates the potential of HJ-1 CCD data combined with linear spectral unmixing and an inverted geometric-optical model for the retrieval of the shrub LAI in Wushen Banner of Inner Mongolia in the Mu Us ***(Moderate Resolution Atmospheric Radiance and Transmittance Model) was used for atmospheric *** was extracted using the threshold of the normalized difference vegetation index,with which water bodies and farmland were separated,in combination with a vegetation map of the People's Republic of China(1:1000000).Using the geometric-optical model,we derive the per-pixel reflectance as a simple linear combination of two components,namely sunlit background and *** fraction of sunlit background is related to the shrub *** the support of HJ-1 CCD data,we employ linear spectral unmixing to obtain the fraction of sunlit background in an atmospherically corrected HJ *** addition,we use the measured shrub canopy structural parameters for shrub communities to invert the geometric-optical model and retrieve the pixel-based shrub *** total,18 sample plots collected in Wushen Banner of Inner Mongolia are used for *** results of the shrub LAI show good agreement with R2.of 0.817 and a root-mean-squared error of 0.173.

关键词： shrub leaf area index inversion HJ-1 data geometric-optical model MODTRAN Mu Us Sandland

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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 {2. of {3. 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 1. institute of geographical {2. and Natural {3. 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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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. sciences and Natural resources research,t he chinese academy of sciences,Beijing 100101,P.R.China 2.Information Consultative Center,institute of Macro-economy,Natio nal Planning institute of geographical {2. and Natural {3. research， the chinese academy of sciences， 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 natural 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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Spatiotemporal variations of vegetation cover on the chinese Loess Plateau(1981―2.06):Impacts of climate changes and human activities

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Science China Earth sciences 2008年第1期51卷 67-78页

作者： XIN ZhongBao1,2. xu jiongxin1 & ZHENG Wei1, 2.1 {2. of Geographic sciences and Natural resources research, chinese academy of sciences, Beijing 100101, China 2.Graduate University of the chinese academy of sciences, Beijing 100049, China 1. institute of Geographic sciences and Natural {2. {3. Chinese Academy of Sciences Beijing 100101 China 2. Graduate University of the chinese academy of sciences Beijing 100049 China

Spatiotemporal variations of chinese Loess Plateau vegetation cover during 1981-2.06 have been investigated using GIMMS and SPOT VGT NDVI data and the cause of vegetation cover changes has been analyzed, considering the climate changes and human activities. Vegetation cover changes on the Loess Plateau have experienced four stages as follows: (1) vegetation cover showed a continued increasing phase during 1981―1989; (2. vegetation cover changes came into a relative steady phase with small fluctuations during 1990―1998; (3. vegetation cover declined rapidly during 1999―2.01; and (4) vegetation cover increased rapidly during 2.02.2.06. The vegetation cover changes of the Loess Plateau show a notable spatial difference. The vegetation cover has obviously increased in the Inner Mongolia and Ningxia plain along the Yellow River and the ecological rehabilitated region of Ordos Plateau, however the vegetation cover evidently decreased in the hilly and gully areas of Loess Plateau, Liupan Mountains region and the northern hillside of Qinling Mountains. The response of NDVI to climate changes varied with different vegetation types. NDVI of sandy land vegetation, grassland and cultivated land show a significant increasing trend, but forest shows a decreasing trend. The results obtained in this study show that the spatiotemporal variations of vegetation cover are the outcome of climate changes and human activities. Temperature is a control factor of the seasonal change of vegetation growth. The increased temperature makes soil drier and unfavors vegetation growth in summer, but it favors vegetation growth in spring and autumn because of a longer growing period. There is a significant correlation between vegetation cover and precipitation and thus, the change in precipitation is an important factor for vegetation variation. The improved agricultural production has resulted in an increase of NDVI in the farmland, and the implementation of large-scale vegetation construction has

关键词： Loess Plateau vegetation cover climate changes human activities GIMMS

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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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ZONAL CHARACTERISTICS OF SEDIMENT YIELD OF RIVER BASINS CHINA

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International Journal of Sediment research 1995年第2期 35-45页

作者： xu jiongxin( {2. of Geography,{3., Beijing 100101, China)

ＺＯＮＡＬＣＨＡＲＡＣＴＥＲＩＳＴＩＣＳＯＦＳＥＤＩＭＥＮＴＹＩＥＬＤＯＦＲＩＶＥＲＢＡＳＩＮＳＣＨＩＮＡＸＵＪｉｏｎｇｘｉｎ（Ｐｒｏｆｅｓｓｏｒ，ＩｎｓｔｉｔｕｔｅｏｆＧｅｏｇｒａｐｈｙ，ＣｈｉｎｅｓｅＡｃａｄｅｍ...

ＺＯＮＡＬＣＨＡＲＡＣＴＥＲＩＳＴＩＣＳＯＦＳＥＤＩＭＥＮＴＹＩＥＬＤＯＦＲＩＶＥＲＢＡＳＩＮＳＣＨＩＮＡＸＵＪｉｏｎｇｘｉｎ（Ｐｒｏｆｅｓｓｏｒ，ＩｎｓｔｉｔｕｔｅｏｆＧｅｏｇｒａｐｈｙ，ＣｈｉｎｅｓｅＡｃａｄｅｍｙｏｆＳｃｉｅｎｃｅｓ，Ｂｅｉｊｉ...

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