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Redevelopment of liftoff rates of saltating sand grains based on a simple optimization model

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Science china Earth Sciences 2010年第4期53卷 568-574页

作者： CHENG Hong & ZOU XueYong State key laboratory of Earth Surface Processes and Resource Ecology,beijing {3. university,beijing 1.0875,china MOE Engineering Center of Desertification and Blown-sand Control,beijing {3. university,beijing 1.0875,china key laboratory of environmental change and natural disaster of the Ministry of education of china,beijing {3. university,beijing 1.0875,china State key laboratory of Earth Surface Processes and Resource Ecology Beijing Normal University Beijing China MOE Engineering Center of Desertification and Blown-sand Control Beijing Normal University Beijing China key laboratory of {2. {3. and natural disaster of the Ministry of education of china Beijing Normal University Beijing China

This paper is a redevelopment result of liftoff rates of saltating sand grains based on our previous *** sand flow is a complex multi-phase flow because of a special two-phase gas-solid flow near ground *** extensive research on the movement of blowing sand,no model fully characterizes aeolian sand flow,and large differences often exist between simulations of aeolian sand movement and field *** key problem is a few of sufficient research on liftoff rates of saltating sand grains(also called the number of liftoff sand grains per unit time and per unit bed area).It is necessary to re-search in advance liftoff rates of saltating sand *** redeveloped liftoff rates of saltating sand grains by establishing an optimization model based on the flux of aeolian sand flow at different heights of the sampler in wind tunnel and the simulated capture of saltating sand grains by different heights of the sampler that are from different liftoff position(distance from the sampler) in order to revise previous inversion condition of liftoff rates of saltating sand *** rates increased rapidly with increasing wind *** frictional wind velocities of u=0.67,0.77,0.82.0.83.and 0.87 m s-1,liftoff rates were 3.40,954502.52.5114,5499407,and 76962.1 sand grain s-1 m-2.*** rates could be expressed as the square of the instantaneous frictional wind velocity and a constant(0.663. that differs from the critical(threshold) frictional wind velocity at which saltation *** our results require additional experimental validation and the simple optimization model must be improved,they nonetheless provide a strong basis for future research.

关键词： liftoff rates of saltating sand grains optimization model wind tunnel two-phase gas-solid flow

Edaphic factors determining variation of two ecotypes of Leymus chinensis in North china

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Progress in natural Science:Materials International 2006年第11期16卷 1150-1155页

作者： ZHOU Chan~1 and YANG Yunfei~2.*(1. MOE key laboratory of {2. change and natural disasters, College of Resources Science and Technology, beijing normal university, beijing 1.0875, china 2. key laboratory of Vegetation Ecology, Ministry of {13., Institute of Grassland Science, Northeast {12. university, Changchun 13.02., china) MOE key laboratory of {2. {3. and natural disasters College of Resources Science and Technology Beijing Normal University Beijing 100875 China key laboratory of Vegetation Ecology Ministry of Education Institute of Grassland Science Northeast Normal University Changchun 130024 China

To identify ecotypic variation of L. chinensis, the physiological characteristics and environmental factors were measured and assessed for grey-green and yellow-green ecotypes of L. chinensis grown in the salt-alkalized and aeolian sandy soils. Although both ecotypes presented a similar salt-alkaline tolerance under the experimental conditions, they differed in several aspects. The L. chinensis grown in the aeolian sandy soils had higher water potential and chlorophyll content and lower proline content in their leaves than those grown in the salt-alkalized habitat, and the grey-green ecotype of L. chinensis in both types of soils had higher water potential, chlorophyll and proline contents than the yellow-green ecotype. Besides, grey-green ecotypes had higher salt-alkaline tolerance than the yellow-green ecotype. The stepwise regression analysis showed that soil conductance and pH value were the main ecological factors affecting the physiology of L. chinensis. From the natural distribution of the two ecotypes, we considered that salt-alkaline in the soils is the leading factor in determining ecotypic variation of L. chinensis. The two ecotypes were first named grey-green and yellow-green ecotypes respectively.

关键词： L.chinensis ecotype adaptability variation ecological factor salt-alkaline in soil.

Study on Water Consumption Coefficient of People's Living and Its Regional Disparity in the North of china

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Chinese Journal of Population,Resources and Environment 2005年第2期3卷 20-26页

作者： Wang Jing’ai 1-3. Mao Rui 3.4, Yang Mingchuan 3.4 & Zhou Junju 11 College of Geography & Remote Sensing 2.key laboratory of Regional Geography of{2. 3.key laboratory of environmental change and natural disaster of Ministry of education of china 4 College of Resources Science & Technology,{2.,{12., china College of Geography and Remote Sensing Beijing 100048 China key laboratory of {2. {3. and natural disaster of Ministry of education of china Beijing 100048 China College of Resources Science and Technology Beijing Normal University Beijing 100875 China

By employing the information-reshufflingmethod that integrates census data, precipitation dataand inquiry data of water consumption, this paperdiscusses 5 (water consumption coefficient of people’sliving) in allusion to different precipitation zones anddifferent periods of time. The study shows that 5-(water consumption coefficient of urban people’sliving), 5. (water consumption coefficient of ruralpeople’s living) and increase with time passing, andthe increasing extent of 5 is 1.84, 2.62. 2.84 and 2.68times respectively from the west to the east, whichresults from the total quantity of water resources andthe speed of urbanization. 5- and 5. of eachprecipitation zone increased with 5- increasing morequickly than 5., and the difference between the twoalso increased when time passed. In the past fifty years(1950-2.00), the increasing extent of 5- was 1.71,2.96, 2.41 and 2.3. times respectively from the westto the east, in which 2.0-400mm precipitation zoneincreased more than others. Meanwhile the increasingextent of 5. is 1.55, 1.60, 1.53.and 1.64 timesrespectively from the west to the east with eachprecipitation zone increasing similarly. The change of5-is due to the speed of urbanization and the stabilityof water resources. This study provides basis forcalculating the water demand of people’s living andrevealing the impact of water demand of people’s livingon ecological drought in different zones.

关键词： The north of china precipitation zone water consumption coefficient of people’s living

Developing land use scenario dynamics model by the integration of system dynamics model and cellular automata model

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Science china Earth Sciences 2005年第11期48卷 1979-1989页

作者： HE Chunyang, SHI Peijun, CHEN Jin, Li Xiaobing, PAN Yaozhong, LI Jing, LI Yuechen & LI Jinggang key laboratory of {2. {3. and natural disaster, Ministry of education of china, beijing normal university College of Resources Science & Technology, beijing normal university, beijing 1.0875, china key laboratory of {2. {3. and natural disaster Ministry of Education of China Beijing Normal University China College of Resources Science & Technology Beijing Normal University Beijing China

Modeling land use scenario changes and its potential impacts on the structure and function of the ecosystem in the typical regions are helpful to understanding the interactive mechanism between land use system and ecological system. A Land Use Scenario Dynamics (LUSD) model by the integration of System Dynamics (SD) model and Cellular Automata (CA) model is developed with land use scenario changes in northern{2. in the next 2. years simulated in this paper. The basic idea of LUSD model is to simulate the land use scenario de-mands by using SD model at first, then allocate the land use scenario patterns at the local scale with the considerations of land use suitability, inheritance ability and neighborhood effect by using CA model to satisfy the balance between land use scenario demands and supply. The application of LUSD model in northern{2. suggests that the model has the ability to reflect the complex behavior of land use system at different scales to some extent and is a useful tool for assessing the potential impacts of land use system on ecological system. In addition, the simulated results also indicate that obvious land use changes will take place in the farming-pastoral zone of northern{2. in the next 2. years with cultivated land and urban land being the most active land use types.

关键词： system dynamics, cellular automata, scenario, land use, model

Test of magnetic susceptibility and grain-size age models of loess

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Progress in natural Science:Materials International 2007年第11期17卷 1312-1317页

作者： Chen Yimeng1,2.3. Feng Zhaodong4 and Gong Huili1,2.1. MOE and key {3. of Resources Environment and GIS of {2., {2. 10003., china 2. key {3. of 3. information Acquisition and Application, The Capital normal university, {2. 10003., china 3. Department of Economics & Management of Huizhou university, Huizhou 516007, china 4. key {3. of Western china’s environmental Systems, Ministry of education, Lanzhou university, Lanzhou 73.000, china) key laboratory of Resources Environment and GIS of {2. Beijing 100037 China key laboratory of 3. information Acquisition and Application Capital Normal University Beijing 100037 China Department of Economics and Management Huizhou University Huizhou 516007 China key laboratory of Western{2.'s {3. Systems Lanzhou University Lanzhou 730000 China

Ages of the stratigraphic boundary MIS1/2.and MIS3.4 of the Yuanbu loess section in Linxia are used as the basis of the nodal control age. The age of MIS1/2.and MIS3.4 are obtained from the latest international research result—the climatic events recorded in the stalagmite in the Hulu Cave in Nanjing, that MIS1/2.is 11.5 kaB.P. and MIS3.4 is 59.8 kaB.P.. The ages of the two climatic events contain three nodal age control models (Model 1: 0 kaB.P.—59.8 kaB.P.; Model 2. 0 kaB.P.—11.5 kaB.P. and 11.5 kaB.P.—59.8 kaB.P.; Model 3. 11.5 kaB.P.—59.8 kaB.P.), which are used as the nodal control age separately. The deposition times of various stratigraphic horizons are calculated by using the magnetic susceptibility age model and grain-size age model, and then compared with each other. In addition, the AMS14C age, OSL age and the ages of YD and H events are compared with the ages of the corresponding horizons calculated by the three models of nodal control ages. From the analyses of lithologic characters and climatic stages it has been found that both the magnetic susceptibility age model and the grain-size age model have some defects. Because the accurate control ages are selected as the nodal points of the glacial period or interglacial period, the stratigraphic deposition times determined by the high resolution of magnetic susceptibility age model and grain-size age model approximate to the actual ages. As for the relative accuracy of the two age models, the magnetic susceptibility age model is more accurate than the grain-size age model.

关键词： loess nodal control age magnetic susceptibility age model grain-size age model test

Preliminary results of the study on wind erosion in the Qinghai-Tibetan Plateau using 13.Cs technique

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Chinese Science Bulletin 2000年第11期45卷 1019-1025页

作者： YAN Ping, DONG Guangrong, ZHANG Xinbao & ZHANG Yiyun1. key laboratory of {2. {3. and natural disaster, the Ministry of education of china, beijing normal university, beijing 1.0875, china 2. Institute of Desert Research, Chinese Academy of Sciences, Lanzhou 73.000, china 3. Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, china 4. Department of Physics, Sichuan Union university, Chengdu 610041, china key laboratory of {2. {3. and natural disaster the Ministry of Education of China Beijing Normal University Beijing China Institute of Desert Research Chinese Academy of Sciences Lanzhou China Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu China Department of Physics Sichuan Union University Chengdu China

The worldwide fallout of caesium-13. (13.Cs) associated with the nuclear weapon tests during the 1950s and 1960s has provided a valuable man-made tracer for studies of soil erosion and sediment delivery. But relatively few researchers have used it to estimate wind erosion. In this note, the 13.Cs technique is introduced into the studies of wind erosion and its modern processes inthe Qinghai-Tibetan Plateau. Two 13.Cs reference inventories of 982.11 and 2.3.6.04 Bq · m-2.wereestablished preminarily, distributed in the south and middle-north parts of the studied arearespectively. By analyzing the patterns of 13.Cs depth profiles from sampling sites, the aeolianprocesses of erosion and deposition in nearly 40 years have been revealed, i.e. the shrub coppicedunes (S1) and semi-fixed dunefields (S3. experienced the alternation of erosion and deposition,while the grasslands (S4, S6 and S7) and dry farmlands (S5) suffered erosion only. By using 13.Csmodel, the average wind erosion rates for shrub coppice

关键词： 13.Cs technique Qinghai-Tibetan Plateau wind erosion.

Flooding 1990s along the Yangtze River, has it concern of global warming?

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Journal of Geographical Sciences 2001年第1期11卷 43-52页

作者： GONG Dao-yi1, ZHU Jin-hong2. WANG Shao-wu2.(1. key {3. of {2. change and natural disaster, Institute of Resources Science, beijing normal university, beijing 1.0875, china 2. Department of Geophysics, Peking university, {13. 100871, key laboratory of {2. {3. and natural disaster Institute of Resources Science Beijing Normal University Beijing China Department of Geophysics Peking University Beijing China

There were a series of severe floods along the middle to lower reaches of the Yangtze River (Changjiang River) in china during the 1990s. The extensive summer (June, July and August) precipitation is mostly responsible for the flooding. The summer rainfall in the 1980s and the 1990s is much higher than that in the previous 3.decades. The means for 1990–1999 is +87.62.mm above normal, marked the 1990s the wettest decade since the 1950s. Six stations with a time span of 1880–1999 are selected to establish century-long rainfall series. This series also shows that the 1990s is the wettest decade during the last 12. years. In the wettest 12.years, four occurred in the 1990s (1991, 1996, 1998 and 1999). Both global and china’s temperature show there is a relative lower air temperature during the 1960–1970s, and a rapid warming in the 1980–1990s. Comparisons of rainfall between 1960–1979 and 1980–1999 show there are dramatic changes. In the cold period 1960–1979, the summer rainfall along the Yangtze River is 3.8 % to 4.7 % below the normal, during the warm period 1980–1999, over 8.4 % to 18.2.% of summer rainfall occurs. Over the whole eastern china, the summer rainfall shows opposite spatial patterns from the 1960–1970s to 1980–1990s. The consistent trend toward more rainfall with global warming is also presented by the greenhouse scenario modeling. A millennial Drought/flood Index for the middle to lower reaches of the Yangtze River showed that although the surplus summer rainfall in the 1990s is the severest during the past 150 years, it is not outstanding in the context of past millennium. Power spectra of the Drought/flood Index show significant interdecadal periods at 3..3.and 11.8 years. Thus, both the natural interdecadal variations and the global warming may play important roles in the frequent floods witnessed during the last two decades.

关键词： summer rainfall Yangtze River global warming interdecadal variation

^(13.)Cs tracing of lacustrine sediments in the Dalian Lake,Qinghai Province,china

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Chinese Science Bulletin 2001年第S1期46卷 83-87页

作者： VAN Ping, DONG Guangrong & DONG Zhibaochina Certer of Desert Research at beijing normal university, {2.{3., china:key laboratory of environmental change and natural disaster, the Ministry of education of china, beijing normal university, beijing 1.0875, china Cold and Arid Regions environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 73.000, china china Certer of Desert Research at beijing normal university Beijing China key laboratory of {2. {3. and natural disaster The Ministry of Education of China Beijing Normal University Beijing China Cold and Arid Regions environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou China

Based upon the analysis of Cs and grain-size parameters, the total amounts of 13.Cs deposition by wind and water in the Dalian Lake of Gonghe Basin, Qinghai Province are defined. The vertical profile of 13.Cs in the lacustrine sediments exhibits three 13.Cs activity maxima and one minimum. The major maximum corresponds to the global I3.Cs fallout in 1963. the two secondary maxima correspond to the leakage of the Chernobyl reactor in 1986 and complete desiccation of the lake in 1994, respectively. The minimum corresponds to aeolian deposition caused by extensive reclamation in the late 1980s and early 1990s. The 13.Cs data set was used to evaluate average sedimentation rate of the Dalian Lake since 1963. The deposition was stable in 1963.1986 and 1994-1998, and it was rapid during 1986?994. This preliminary study reveals that l3.Cs has the same potential to trace environmental changes introduce by human interference in arid/semiarid regions as in humid regions.

关键词： 13.Cs technique Dalian Lake sedimentation rate.

Estimation of regional evapotranspiration over Northwest china using remote sensing

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Journal of Geographical Sciences 2001年第2期11卷 140-148页

作者： CHEN Yun-hao, LI Xiao-bing, SHI Pei-jun (Institute of Resources Science, beijing normal university, key {2. of {3. change and natural disaster, Ministry of education of china, beijing 1.0875, china) Institute of Resources Science Beijing Normal University Key Laboratory of Environmental Change and Natural Disaster Ministry of Education of China

It is a very complicated problem to estimate evapotranspiration (ET) over a large area of land surface. In this paper, the evapotranspiration estimation models for dense vegetation and bare soil are presented, based on the information of parameters like vegetation cover-degree and surface albedo. Combined with vegetation cover-degree data, a model for regional evapotranspiration estimation over the heterogeneous landscape is derived. Through a case study using remote sensing data over Northwest china, the accuracy of the model for regional evapotranspiration estimation is checked. The result shows that the accuracy of the model is satisfactory. The features of evapotranspiration over Northwest china are also discussed with the application of the model.

关键词： evapotranspiration remote sensing vegetation cover-degree Northwest china