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Processes and modes of permafrost degradation on the Qinghai-Tibet Plateau

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Science china Earth sciences 2010年第11期53卷 150-158页

作者： WU JiChun,SHENG Yu,WU QingBai & WEN Zhi State Key Laboratory of Frozen Soil engineering,cold and {2. regions environmental and engineering research institute.chinese academy of sciences,lanzhou {12.china State Key Laboratory of Frozen Soil engineering Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou China

Climate warming must lead the mainly air temperature controlled permafrost to *** on the numerical simulation,the process of permafrost degradation can be divided into five stages,i.e.,starting stage,temperature rising stage,zero geothermal gradient stage,talic layers stage,and disappearing stage,according to the shape of ground temperature *** on the Qinghai-Tibet Plateau (QTP) is generally considered a relic from late Pleistocene,and has been degenerating as a whole during *** to spatial-temporal compensation,the present thermal state discrepancy of permafrost in different areas on the QTP may correspond with their degradation *** the QTP,permafrost in the high and middle mountains belongs to temperature rising stage,the permafrost thermal state is transiting from late rising temperature stage to zero geothermal gradient stage that is distributed in the *** that is in a zero gradient stage mainly appears in the high plateau and valley,whereas the transition from zero gradient stage to talic layers stage of permafrost is located in the vicinity of the lower limit of permafrost,and permafrost is disappearing from margin of perennially frozen *** are two modes of perennially frozen ground thawing,thawing from top to bottom and thawing from bottom to top *** the temperature rising stage,when the heat flux in the perennially frozen soil layer is less than that in the unfrozen soil underlying frozen soil layer,the geothermal flux is partly used to thaw the base of permafrost,and permafrost thaws from bottom to *** the decrease of thermal gradient in the perennially frozen ground,the heat that is used to thaw permafrost base increases,and geothermal heat will be entirely consumed to thaw the base of permafrost until the temperature gradient reaches zero thermal gradient *** the other hand,the disappearance of permafrost may be delayed by "thermal offset" and "seas

关键词： Qinghai-Tibet Plateau permafrost degradation process degradation stage degradation mode

Effect of climatic change on snowmelt runoffs in mountainous regions of inland rivers in Northwestern china

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Science china Earth sciences 2006年第8期49卷 881-888页

作者： WANG Jian1 & LI Shuo2.1. cold and arid {2. environmental and engineering research institute. chinese academy of sciences, lanzhou 730000. china 2. College of Geography, Nanjing Normal University, Nanjing 2.0097, china cold and arid {2. environmental and engineering research institute Chinese Academy of Sciences Lanzhou China College of Geography Nanjing Normal University Nanjing China

Climatic change has significant impacts on snow cover in mid-latitude mountainous re- gions, in the meantime, spatial and temporal changes of snow cover and snowmelt runoffs are con- sidered as sensitive indicators for climatic change. In this study, the upper Heihe Watershed in the Qilian Mountains was selected as a typical area affected by snow cover and snowmelt runoffs in northwestern china. The changes in air temperatures, precipitation, snowfall and spring snowmelt runoffs were analyzed for the period from 1956 to 2.01. The results indicate that climatic warming was apparent, particularly in January and February, but precipitation just fluctuated without a clear trend. The possible changes of snowmelt runoffs in the upper Heihe watershed in response to a warming of 4℃ were simulated using Snowmelt Runoff Model (SRM) based on the degree-day factor algorithm. The results of the simulation indicate that a forward shifting of snow melting season, an increase in water flows in earlier melting season, and a decline in flows in later melting season would occur under a 4℃ warming scenario.

关键词： climatic changes, snowmelt runoff, SRM model, upper Heihe Watershed, simulating.

Review of several problems on the study of eco-hydrological processes in arid zones

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chinese Science Bulletin 2002年第5期47卷 353-360页

作者： ZHAO Wenzhi & CHENG Guodongcold and arid {2. environmental and engineering research institute. chinese academy of sciences, lanzhou 730000. china State Key Laboratory of Frozen Soil engineering, chinese academy of sciences, lanzhou 730000. china cold and arid {2. environmental and engineering research institute Chinese Academy of Sciences Lanzhou China State Key Laboratory of Frozen Soil engineering Chinese Academy of Sciences Lanzhou China

Ecosystem degradation is a common and cardinal environmental problem in arid zones. The change in the eco-hydrological processes is the basic cause responsible for such a problem. The study on the eco-hydrological processes in arid zones has become a forefront and focus of the eco-environmental research. Recent studies on eco-hydrological processes in arid zones show that the primary vegetation pattern and its eco-hydrological effect are of the most stable state of the ecosystem in arid zones. Special water absorption ways of plants in arid zones and the hydraulic lift and reverse hydraulic lift functions of some plants are the key mechanisms to maintain the stability of the ecosystem in arid zones. In the case of water shortage, ensuring ecological water requirement and maintaining proper ecological ground- water table are the prerequisite to keep healthful operation of the ecosystem in arid zones. The paper reviews some advances in the study of eco-hydrological processes in arid zones. It puts

关键词： arid zone vegetation pattern eco-hydrological effect hydraulic lift plant water source ecological water requirement.

Dynamic calculation model and seismic response for frame supporting structure with prestressed anchors

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Science china(Technological sciences) 2010年第7期53卷 1957-1966页

作者： DONG JianHua1’2. ZHU YanPeng1, ZHOU Yong1 & MA Wei2.1 College of Civil engineering, lanzhou University of Technology, lanzhou 730050, china 2.State Key Laboratory of Frozen Soil engineering, cold and arid regions environmental and engineering research institute. {12. academy of sciences, lanzhou 730000. china College of Civil engineering Lanzhou University of Technology Lanzhou China State Key Laboratory of Frozen Soil engineering Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou China

A dynamic calculation model of frame supporting structures with prestressed anchors for the slope stability is proposed. The frame and soil are closely contacted in the role of prestressed anchors and they cannot be separated along the whole slope. The lateral displacement of frame and soil is nearly in phase. The movement characteristic satisfies the theory of elastic foundation beam. The frame is treated with elastic foundation beam in this model. The influence of prestressed anchors is simplified as linear spring and damped system related with velocity. Under the condition of horizontal earthquake excitation, the equation of vibration response is established by using the model of dynamic Winkler beam and the analytical solutions are obtained for simple harmonic vibration. This method is applied to a case record for illustration of its capability, in order to verify the method, 3D nonlinear FEM (ADINA) is used to analyze the seismic performance of this case, the comparative results show that the design and the analysis are safe and credible by using the proposed method. The calculation model provides a new way for earthquake analysis and seismic design of slope stability supported by frame structure with prestressed anchors.

关键词： frame supporting structure with prestressed anchor slope dynamic calculation model seismic performance seismic design

research progress of desert science in china

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chinese Science Bulletin 2000年第24期45卷 2209-2213页

作者： XIA Xuncheng & FAN ShengyueXinjiang institute.of Ecology and Geography, chinese {2. of sciences, Urumqi 830011, china cold and arid Region Environment and engineering research institute. chinese {2. of sciences, lanzhou 730000. china Xinjiang institute.of Ecology and Geography Chinese Academy of Sciences Urumqi China cold and arid Region Environment and {2. research Instiute Chinese Academy of Sciences Lanzhou China

research of desert science in china began in the 1930s, when Chen Zongqi et al. first made apreliminary investigation in several deserts. Shortly after the founding of the People’s Republic ofchina a few studies were carried out to meet the demand for the establishment of windbreak andsandbreak forests, for example, the studies of moving sand dunes in Yulin. Jingbian and Dingbianregions of Shaanxi Province. However, the comprehensive study of desert science in china

关键词： research progress of desert science in china

Indian monsoon influences altitude effect of δ^(18)O in precipitation/river water on the Tibetan Plateau

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chinese Science Bulletin 2009年第15期54卷 2724-2731页

作者： YAO TanDong1,2. ZHOU Hang1,3 & YANG XiaoXin1,3 1 Key Laboratory of Tibetan Environment Changes and Land Surface Processes, institute.of Tibetan Plateau research, {2. academy of sciences, Beijing 100085, china 2.State Key Laboratory of Cryosphere sciences, cold and arid regions environmental and engineering research institute. {2. academy of sciences, lanzhou 730000. china 3 Graduate University of {2. academy of sciences, Beijing 100049, china Key Laboratory of Tibetan Environment Changes and Land Surface Processes Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China State Key Laboratory of Cryosphere sciences Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou China Graduate University of chinese academy of {2. Beijing China

The δ 18O variation in precipitation acquired from 2. stations within the network of Tibetan Observation and research Platform(TORP)is studied, with the focus on the altitude effect of δ 18O in river water during monsoon precipitation in an effort to understand the monsoon influence on isotopic composition in annual river water. It is found that δ 18O in precipitation on the Plateau is influenced by different moisture sources, with significant Indian monsoon influence on δ 18O composition in plateau precipitation and river water. The δ 18O of water bodies in the monsoon domain is generally more depleted than that in the westerly domain, suggesting gradual rainout of southwesterly borne marine moisture in the course of long-distance transportation and lifting over the Himalayas. The lapse rate of δ 18O in river water with altitude is the largest during monsoon precipitation, due to the increased temperature vertical gradient over the southern Plateau region controlled by monsoon circulation. The combination of δ 18O in river water in monsoon (wet) and non-monsoon (dry) seasons shows a larger lapse rate than that in non-monsoon (dry) season alone. As the altitude effect of δ 18O in precipitation and river water on the Tibetan Plateau results from the combined effect of monsoon moisture supply and westerly moisture supply, the δ 18O composition and its altitude effect on the Plateau during monsoon seasons should be considered in the reconstruction of paleoelevation of the Tibetan Plateau.

关键词：印度季风青藏高原降水

Effects of sunspot cycle length and CO_2.on air temperature along Qinghai-Xizang railway and air temperature's trend prediction

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Science china Earth sciences 2004年第Z1期47卷 131-141页

作者： LI Dongliang, QUO Hui, WANG Wen & WEI Licold & arid {2. environmental and engineering research institute. chinese academy of Science, lanzhou 730000. china Department of Atmospheric sciences, lanzhou University, lanzhou 730000. china cold & arid {2. environmental and engineering research institute Chinese Academy of Science Lanzhou China Department of Atmospheric sciences Lanzhou University Lanzhou China

There are well coherences between annual averaged air temperatures at every meteorological station along the Qinghai-Xizang railway, and its 10-year moving average correlation coefficient is 0.92. Thus, the regional averaged annual mean temperature series along the Qinghai-Xizang railway (Trw) from 1935 to 2.00 are constructed. The investigation is suggested that: Trw had significant responses to the 5-year lagged sunspot cycle length (SCL) and 15-year lagged concentration of atmospheric carbon dioxide (CO2., and the correlation coefficients between them are -0.76 (SCL) and 0.88 (CO2., respectively. The future SCL is predicted by the model of average generated function constructed with its main cycles of 76a, 93a, 108a, 2.5a and 2.5a. The result shows that the SCL would be becoming longer in the first half of the 2.st century, and then it could be becoming shorter in the second half of the 2.st century. Based on the natural change of SCL and the effect of double CO2.concentration, Trw in the 2.st century is forecasted. It could warm up about 0.50℃ in the first half of the 2.st century compared with the last decade of last century. The mean maximum air temperature could be likely about 0.2.℃ in July and from 0.40℃ to 1.10℃ in January. The annual air temperature difference would likely reduce 0.3-1.00℃. The probability of above predictions ranges from 0.64 to 0.73.

关键词： Qinghai-Xizang railway, annual mean air temperature, sunspot cycle length (SCL), atmospheric carbon dioxide concentration (CO2., prediction.

Respondence and feedback of modern sand deserts to climate change ——A case study in Gurbantunggut Desert

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chinese Science Bulletin 2000年第12期45卷 1137-1142页

作者： WEI WenshouXinjiang institute.of Ecology and Geography, chinese {2. of sciences, Urumqi 830011, china Open Laboratory of Ice-Core, cold and arid regions environmental and engineering research institute. chinese {2. ofsciences, lanzhou 730000. china Xinjiang institute.of Ecology and Geography Chinese Academy of Sciences Urumqi 830011 China Open Laboratory of Ice-Core Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China

The research on the respondence and feedback of modern sand deserts to the climate change is an important component part in the studies on the global climate change. Deserts respond to the climate change, meanwhile, they affect the climate with their feedback of peculiar environment during the respondence. Many researches on desert climate have been carried out at home and abroad. However, there is little research on the respondence and feedback of modern fixed, semi-fixed and mobile deserts in arid areas to the climate change, in which the factor analysis as well as the parameter changing effects is especially the difficult problem all along. In this note, the parameters of the respondence and feedback of Gurbantunggut Desert to the climate change are measured and analyzed, some variable parameters of water-heat exchange are obtained, and a numerical model of desertification is developed according to a series of climate change of about 40 years and the variable relations of meteorological and physical

关键词： Gurbantunggut Desert climate change respondence and feedback numerical model.

Impact of land-use change on hydrological processes in the Maying River basin, china

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Science china Earth sciences 2006年第10期49卷 1098-1110页

作者： WANG Genxu1,3, ZHANG Yu2. LIU Guimin2.& CHEN Lin3 1. institute.of Mountain Hazards and Environment, chinese {2. of sciences, Chengdu 610041, china 2. cold and arid regions environmental and engineering research institute. chinese academy of sciences, lanzhou 730000. china 3. Resource and Environment School, lanzhou University, lanzhou 730000. china institute.of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu China Resource and Environment School Lanzhou University Lanzhou China cold and arid {2. environmental and engineering research institute Chinese Academy of Sciences Lanzhou China

Since the 1960s, dramatic changes have taken place in land-use patterns characterized by the persistent expansion of cultivated land and a continuous decrease in natural woodland and grassland in the arid inland river basins of china. It is very important to assess the effects of such land-use changes on the hydrological processes so vital for water resource management and sustainable development on the catchment scale. The Maying River catchment, a typical arid inland watershed located in the middle of the Hexi Corridor in northwest china, was the site chosen to investigate the hydrological responses to land-use changes. The annual runoff, base flow, maximum peak flow, and typical seasonal runoff in both spring and autumn flood periods were selected as the variables in the hydrological processes. Statistical-trend analysis and curvilinear regression were utilized to detect the trends in hydrological variables while eliminating the climatic influence. The relationship between cultivated land-use and hydrological variables was analyzed based on four periods of land-use variation data collected since 1965. A runoff model was established composed of two factors, i.e., cultivated land use and precipitation. The impact of land use changes, especially in the large ar- eas of upstream woodland and grassland turned into cultivated lands since 1967, has resulted in a mean annual runoff decrease of 2..12., a base flow decline of 35.32., a drop in the maximum peak discharge of 35.77%, and mean discharge decreases in spring and autumn of 36.05% and 2..87% respectively, of which the contribution of cultivated land expansion to the influence of annual runoff amounts to 77%-80%, with the contribution to the influence of spring discharge being 73%-81%, and that to the influence of base flow reaching 62.-65%. Thus, a rational regulation policy of land use patterns is vitally important to the sustainable use of water resources and the proper development of the entire catchment.

关键词： land-use change, arid inland river catchment, hydrological process, impact, Maying River.