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Impacts of permafrost changes on alpine ecosystem in Qinghai-Tibet Plateau

Science china Earth sciences 2006年第11期49卷 1156-1169页

作者： wang genxu1,3., li yuanshou2 ,{3.,{3., chengdu 610041, china 2. Cold and Arid Regions environmental and Engineering Research institute,{3., Lanzhou 73.000, china 3. Resource and environment School, Lanzhou University, Lanzhou 73.000, china institute of mountain hazards and {{3. Chinese Academy of Sciences Chengdu China Resource and environment School Lanzhou University Lanzhou China Cold and Arid Regions environmental and Engineering Research institute Chinese Academy of Sciences Lanzhou China

Alpine cold ecosystem with permafrost environment is quite sensitive to climatic changes and the changes in permafrost can significantly affect the alpine ecosystem. The vegetation coverage, grassland biomass and soil nutrient and texture are selected to indicate the regime of alpine cold ecosystems in the Qinghai-Tibet Plateau. The interactions between alpine ecosystem and permafrost were investigated with the depth of active layer, permafrost thickness and mean annual ground temperature (MAGTs). Based on the statistics model of GPTR for MAGTs and annual air temperatures, an analysis method was developed to analyze the impacts of permafrost changes on the alpine ecosystems. Under the climate change and human engineering activities, the permafrost change and its impacts on alpine ecosystems in the permafrost region between the Kunlun mountains and the Tanggula Range of Qinghai-Tibet Plateau are studied in this paper. The results showed that the per- mafrost changes have a different influence on different alpine ecosystems. With the increase in the thickness of active layer, the vegetation cover and biomass of the alpine cold meadow exhibit a significant conic reduction, the soil organic matter content of the alpine cold meadow ecosystem shows an exponential decrease, and the surface soil materials become coarse and gravelly. The alpine cold steppe ecosystem, however, seems to have a relatively weak relation to the permafrost environment. Those relationships resulted in the fact that the distribution area of alpine cold meadow decreased by 7.98% and alpine cold swamp decreased by 28.11% under the permafrost environment degradation during recent 15 years. In the future 50 years the alpine cold meadow ecosystems in different geomorphologic units may have different responses to the changes of the permafrost under different climate warming conditions, among them the alpine cold meadow and swamp ecosystem located in the low mountain and plateau area will have a relatively

关键词： permafrost environment, alpine cold ecosystem, statistics relationship, climate change, impacts, Qinghai-Tibet Plateau.

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Response of Biomass Spatial Pattern of Alpine Vegetation to Climate Change in Permafrost Region of the Qinghai-Tibet Plateau,china

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Journal of mountain Science 2010年第4期7卷 301-314页

作者： ZHANG Yu wang genxu wang {{3. College of Resources & environment Lanzhou UniversityLanzhou 730000China institute of mountain hazards and {{3. Chinese Academy of SciencesChengdu 610041China

Alpine ecosystems in permafrost region are extremely sensitive to climate *** determine spatial pattern variations in alpine meadow and alpine steppe biomass dynamics in the permafrost region of the Qinghai-Tibet Plateau,china,calibrated with historical datasets of above-ground biomass production within the permafrost region's two main ecosystems,an ecosystem-biomass model was developed by employing empirical spatialdistribution models of the study region's precipitation,air temperature and soil *** model was then successfully used to simulate the spatio-temporal variations in annual alpine ecosystem biomass production under climate *** a 0.44°C decade-1 rise in air temperature,the model predicted that the biomasses of alpine meadow and alpine steppe remained roughly the same if annual precipitation increased by 8 mm per decade-1,but the biomasses were decreased by 2.7% and 2.4%,respectively if precipitation was *** a 2.2°C decade-1 rise in air temperature coupled with a 12 mm decade-1 rise in precipitation,the model predicted that the biomass of alpine meadow was unchanged or slightly increased,while that of alpine steppe was increased by 5.2%.However,in the absence of any rise in precipitation,the model predicted 6.8% and 4.6% declines in alpine meadow and alpine steppe biomasses,*** response of alpine steppe biomass to the rising air temperatures and precipitation was significantly lesser and greater,respectively than that of alpine meadow biomass.A better understanding of the difference in alpine ecosystem biomass production under climate change is greatly significant with respect to the influence of climate change on the carbon and water cycles in the permafrost regions of the Qinghai-Tibet Plateau.

关键词： Permafrost change Qinghai-TibetanPlateau Alpine ecosystem Grassland biomass Climate change Response model

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Study on the Rainfall and Aftershock Threshold for Debris Flow of Post-earthquake

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Journal of mountain Science 2011年第5期8卷 750-756页

作者： HE Siming li Dexin wu Yong LUO Yu Key laboratory of mountain hazards and Earth Surface Process Chinese Academy of Science Chengdu 610041 China institute of mountain hazards and {{3. Chinese Academy of Science Chengdu 610041 China

Due to the special condition of provenance and disaster environment after "5·12" Earthquake, the probability and conditions of the occurrence of gully debris flow change greatly after the event, which make it difficult to prevent disaster effectively. In this study the hydrological model of ground water table in loose sediment is established. According to infinite slope theory, the safety factor of deposits is defined as the ratio of resistance force to driving force. The starting condition of post-earthquake gully debris flow is clearly studied by analyzing the effects of rainfall intensity, seismic strength, slope gradient and mechanical properties on the balance of accumulation body. Then the formulas of rainfall and aftershock threshold for starting of gully debris flow are proposed, and an example is given to illustrate the effect of rainfall, aftershocks and their coupling action on a debris flow. The result shows the critical rainfall intensity decreases as the lateral seismic acceleration and channel gradient increases, while the critical intensity linearly increases as the friction angle increases.

关键词： Earthquake Hydrological model Debris flow Rainfall threshold

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Discrete Element Modeling of Debris Avalanche Impact on Retaining Walls

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Journal of mountain Science 2010年第3期7卷 276-281页

作者： li Xinpo HE Siming LUO Yu wu Yong Key laboratory of mountain hazards and Earth Surface Process CAS Chengdu 610041 China institute of mountain hazards and {{3. CAS Chengdu 610041 China

In china,gravity retaining walls are widely used as protection structures against rockfalls,debris flows and debris avalanches along the roads in mountainous *** this paper,the Discrete Element Method(DEM) has been used to investigate the impact of granular avalanches and debris flows on retaining *** debris is modeled as two dimensional circular disks that interact through frictional sliding *** basic equations that control the deformation and motion of the particles are introduced.A series of numerical experiments were conducted on an idealized debris slide impacting a retaining *** parametric study has been performed to examine the influences of slope geometry,travel distance of the sliding mass,wall position,and surface friction on the impact force exerted on the *** show that:1) the force achieves its maximum value when slope angle is equal to 60°,as it varies from 3.° to 75°;2) an approximate linear relationship between the impact force and the storage area length is determined.

关键词： Debris flow debris avalanche rockfallretaining wall Discrete Element Method

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Influences of the degradation of swamp and alpine meadows on CO_2 emission during growing season on the Qinghai-Tibet Plateau

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chinese Science Bulletin 2007年第18期52卷 2565-2574页

作者： wang JunFeng wang genxu wang yibo li yuanshou College of Earth and environment sciences Lanzhou University Lanzhou 730000 China institute of mountain hazards and {{3. Chinese Academy of Sciences Chengdu 610041 China Cold and Arid Regions environment and Engineering Research institute Chinese Academy of Sciences Lanzhou 730000 China

CO2 emission fluxes of two types of ecosystem, swamp meadow and alpine meadow, in the Fenghuo- shan region of the Qinghai-Tibet Plateau were studied by the static chamber-portable infrared chro- matographic method. The results showed that there was large difference in the CO2 emission fluxes between the two ecosystems and in the same ecosystem of different degradation degrees. CO2 emis- sion flux of the swamp meadow gradually decreased with increasing degradation degree, while that of the alpine meadow gradually increased with increasing degradation degree except in May. The CO2 emission flux of undegraded swamp meadow was 65.1%―80.3. higher than that of undegraded alpine meadow; and the CO2 emission flux of moderately degraded swamp meadow was 22.1%―67.5% higher than that of alpine meadow; but the CO2 emission flux of severely degraded alpine meadow was 14.3.―29.5% higher than that of swamp meadow. The soil moisture content and temperature in the upper 5 cm soil layer and above-ground biomass were significantly correlated with the CO2 emission fluxes and regarded as the main environment factors to control the CO2 emission.

关键词：青藏高原沼泽草甸高山草甸生长季节二氧化碳释放量降解

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Failure mechanism of retaining wall in earthquake and its seismic design measure

Failure mechanism of retaining wall in earthquake and its se...

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The 4th International Conference on environmental and Engineering Geophysics

作者： Yong wu~(1 2) Siming He~(1 2) Xinpo li~(1 2) 1.Key laboratory of mountain hazards and Surface Process CAS chengdu {{3. china. 2.institute of mountain hazards and environment CAS chengdu {{3. china.

＜正＞The failure of retaining wall in earthquake is the main factor that aggravates the harm of mountain ***,the mechanism such as structure response to seismic is not clear and can’t resolute the interaction mechanism between retaining system and seismic force,thus no effective seismic measures can be used in project at ***,based on energy theory, taken the upper bound theorem as measure,the safety of retaining system is defined,and then the mechanism of input and dissipation of seismic energy is ***,by analyzing the wave characters of destructive earthquake,and according to the flexible retaining theory,a seismic design of retaining wall is *** last,an example is given and shows the seismic behavior of common rigid retaining wall is poor and the structure fails quickly under big seismic force with specific *** the contrary,the new system with EPS damping layer can attenuate seismic energy well.

关键词： Seismic wave failure of retaining wall upper bound theorem energy dissipation flexible protection

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Slope Reinforcement for Housing in Three Gorges Reservoir Area

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Journal of mountain Science 2011年第2期8卷 314-320页

作者： wu Faquan LUO Yuanhua CHANG Zhonghua institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China Office of Three Gorges Project Construction Committee the State Council of China Beijing 100038 China

The Three Gorges Project of the Yangtze River is the largest hydropower-complex project under construction in the world. Under the largescale relocation projects, 2874 engineered slopes are formed along with the construction of new towns. In this paper, the cutting slopes are mainly soil slopes and rock slopes. Soil slopes include residual soil slopes, colluvial accumulation slopes, swelling soil slopes, and artificial earth fill slopes, etc. Rock slopes include blocky structure rock slopes, layer structure rock slopes, and clastic structure rock slopes, etc. Varied protection measures have been used for slope protection in the reservoir area including shotcrete concrete-anchor bars, frame beams, retaining walls, slope stabilizing piles, sheet-pile walls, anchorage anti-shear tunnels, flexible protection grids, and drainage, etc. Besides, slope deformation monitoring systems have been set up to monitor deformation failure and the stability state of slopes. The protection measures have guaranteed slope safety and maintained a harmony with the urban environment and surrounding landscape.

关键词： Slope reinforcement Housing for resettlement Three Gorges Reservoir

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长江三峡库区云阳-巫山段斜坡坡度对滑坡的贡献率

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山地学报 2007年第2期25卷 207-211页

作者：乔建平吴彩燕田宏岭中国科学院水利部成都山地灾害与环境研究所中国科学院水利部成都山地灾害与环境研究所四川成都610041

三峡库区滑坡发育与多种因素相关,在它的内部因子中除了地层、斜坡高差和坡向等重要因素外,斜坡的坡度是一个非常重要的条件。为了研究坡度与滑坡发育的关系,借助于GIS技术,利用贡献率法重点研究了三峡库区斜坡坡度对滑坡发育的影响,并... 详细信息

三峡库区滑坡发育与多种因素相关,在它的内部因子中除了地层、斜坡高差和坡向等重要因素外,斜坡的坡度是一个非常重要的条件。为了研究坡度与滑坡发育的关系,借助于GIS技术,利用贡献率法重点研究了三峡库区斜坡坡度对滑坡发育的影响,并且定量地给出了二者的相关关系,即坡度对滑坡发育的贡献。该方法是将坡度划分为若干区间,分析每一区间对滑坡发育所起到的贡献作用,并定量评价了其贡献率的大小。所得研究结果与实际情况较吻合,为库区的滑坡防治规划提供了依据。

关键词：三峡库区坡度滑坡贡献率

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川中丘陵区人工桤柏混交林的研究进展

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水土保持研究 2005年第6期12卷 4-7,45页

作者：吴鹏飞朱波中国科学院成都山地灾害与环境研究所

川中丘陵区人多地少,农业开发历史悠久,垦殖指数高.森林覆盖率低,水土流失严重,给农业和生态环境造成了严重的危害。20世纪70年代,四川省盐亭县林山乡率先把桤木(A luns crem astogyne)和柏木(Cup ressusfunebris)混交成功,到80年代末,... 详细信息

川中丘陵区人多地少,农业开发历史悠久,垦殖指数高.森林覆盖率低,水土流失严重,给农业和生态环境造成了严重的危害。20世纪70年代,四川省盐亭县林山乡率先把桤木(A luns crem astogyne)和柏木(Cup ressusfunebris)混交成功,到80年代末,川中丘陵区营造了大面积的桤柏混交林作为长江上游地区的水土保持林。在过去的3.多年里,有关桤柏混交林生态系统的研究较多,主要集中在混交林的机理和模式、群落结构、生态系统的生物量、生产力和物质循环,以及混交林的生态效应。通过对前人的研究的总结,作者剖析了目前桤柏混交林生态系统存在的问题,并指出今后桤柏混交林的研究应该围绕:(1)混交林生态系统的演替规律与演替趋势;(2)生态系统的稳定性;(3.结构和模式的优化改造三个重点。

关键词：川中丘陵区桤柏混交林生态系统的结构生态系统的功能生态效应

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Study on the impact of vegetation degeneration to hydrology characteristic of the Alpine soil

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Research in Cold and Arid Regions 2011年第3期3卷 233-242页

作者： yibo wang qingbai wu FuJun Niu {{3. wang HuiYan Cheng Laboratory of Frozen Soils CoM and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou Gansu 730000 China College of Earth and environment Science Lanzhou University Lanzhou Gansu 730000 China institute of mountain hazards and {{3. Chinese Academy of Sciences Chengdu Sichuan 610041 China Lanzhou University of Technology Lanzhou Gansu 730000 China

Alpine soil infiltration process is an important part of the hydrological characteristics of alpine soil in permafrost. This research is carried out in the source region of the Yellow River where the permafrost is severely degraded, using various methods for choosing typical sample areas, and to experiment, study and simulate the soil water curve, soil saturated hydraulic conductivity, soil infiltration and soil moisture under different characteristics of degraded vegetation. The results indicate that the empirical equation θ=AS-B, proposed by Gradner and Visser, is very reliable in simulating the soil moisture curve; soil saturated hydraulic conductivity and soil infiltration are significantly different under different vegetation coverage： in the soil surface within 0-10 cm, the saturated hydraulic conductivity and infiltration intensity of Black Beach are the strongest; respectively, in soil layers below 3. cm, vegetation has almost no impacts on the saturated hydraulic conductivity, infiltration intensity and soil moisture content. Significant reduction of soil moisture occurs in soil surfaces with degraded vegetation. The more serious the degradation, the more water loss, and it can be up to 3..6% in the worst situation. Soil moisture of developed vegetation root systems in depths within 10-20 cm has the greatest impact on the soil environment, and the loss of moisture induces difficulty in the restoration of degraded meadows. Through a comparative study, the Kostiakov infiltration equationf（t） = at-b is more applicable for studies on the process of soil moisture infiltration of the alpine meadow in the source region of the Yellow River.

关键词： vegetation degradation alpine soil foil infiltration

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