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81.
Groundwater System Division and Description of Asia 总被引:1,自引:0,他引:1
Based on landform, climate, river system, geological structure and hydrogeological structure and from the perspective of systematology, the groundwater system of Asia can be divided into 36 secondary groundwater systems under 11 primary ones by the intercontinental scale. This forms part of the work of the groundwater series map of Asia, which is compiled according to groundwater system division and evaluation of the total amount and types of aquifer, reflecting the large-scale features of groundwater resources in Asia. Systematic profiling of groundwater in this way provides a scientific basis for groundwater exploitation planning and management in Asia, and avoiding disputes over groundwater resources and the environment among Asian countries. 相似文献
82.
To study the effect of uncertain factors on the temperature field of frozen soil, we propose a method to calculate the spatial average
variance from just the point variance based on the local average theory of random fields. We model the heat transfer coefficient
and specific heat capacity as spatially random fields instead of traditional random variables. An analysis for calculating the random
temperature field of seasonal frozen soil is suggested by the Neumann stochastic finite element method, and here we provide the
computational formulae of mathematical expectation, variance and variable coefficient. As shown in the calculation flow chart, the
stochastic finite element calculation program for solving the random temperature field, as compiled by Matrix Laboratory
(MATLAB) software, can directly output the statistical results of the temperature field of frozen soil. An example is presented to
demonstrate the random effects from random field parameters, and the feasibility of the proposed approach is proven by comparing
these results with the results derived when the random parameters are only modeled as random variables. The results show that
the Neumann stochastic finite element method can efficiently solve the problem of random temperature fields of frozen soil based
on random field theory, and it can reduce the variability of calculation results when the random parameters are modeled as spatially
random fields. 相似文献
83.
香山绝对点周围的局部地壳变形及其对重力测量结果的影响 总被引:1,自引:0,他引:1
为了监视北京地区的地壳稳定性,北京测绘院对10多个基岩点和北京市区进行了多次沉降观测,结果表明香山点近10多年来高程变化只有几毫米,其重力效应可略而不计,但测点东北和东南方有两个较大的下沉区。用线积分法计算了两个局部沉降的重力效应,在沉降区中心其影响可达0.38μms^-2,但对香山点的重力效应非常小,完全可以忽略。因此得出如下结论:香山点观测到的重力变化不是地壳变形引起的。 相似文献
84.
Pollen-based reconstructions of Holocene vegetation and climatic change of Tibetan Plateau 总被引:2,自引:0,他引:2
A synthesis of Holocene pollen records from the Tibetan Plateau shows the history of vegetation and climatic changes during the Holocene. Palynological evidences from 24 cores/sections have been compiled and show that the vegetation shifted from subalpine/alpine conifer forest to subalpine/alpine evergreen sclerophyllous forest in the southeastern part of the plateau; from alpine steppe to alpine desert in the central, western and northern part; and from alpine meadow to alpine steppe in the eastern and southern plateau regions during the Holocene. These records show that increases in precipitation began about 9 ka from the southeast, and a wide ranging level of increased humidity developed over the entire of the plateau around 8-7 ka, followed by aridity from 6 ka and a continuous drying over the plateau after 4-3 ka. The changes in Holocene climates of the plateau can be interpreted qualitatively as a response to orbital forcing and its secondary effects on the Indian Monsoon which expanded northwards 相似文献
85.
86.
A preliminary application GIS in glaciological research along the traverse route from Zhongshan Station to Dome A, Antarctica 总被引:1,自引:0,他引:1
1 IntroductionGeographicalinformationsystem (GIS)isanefficientwayandimportanttechniquetomanage,displayandanalyzeAntarcticspatialdata.GIScanbeusedtomakeandre newmapproductsquickly ,evaluateenvironment,supportlogisticmanagementandfieldoperation,providechancetoextractnewknowledge,andtopromoteinformationex changeamongnationsunderthedemandoftheMadridProtocol(AADC 2 0 0 1 ;MAGIC1 998;1 999) .WorkingGroupofGeodesyandGeographicInformation (WG GGI)ofScientificCommitteeonAntarcticResearch (… 相似文献
87.
Salix gordejevii, a species of dune-fixing pioneer shrub in the Hunshandak Sandland in China, plays a vital role in maintenance and improvement of the local ecological environment. Salix gordejevii has an r-type reproductive countermeasure, which means it produces large quantities of seeds that have a high germination rate but relatively low seedling viability. Our research on the seed regeneration and sprouting regeneration characteristics of Salix gordejevii shows that its sprouting regeneration process is more productive and efficient than its seed regeneration process. At the same time, growth of Salix gordejevii would decline when the drifting sand dune was fixed. To assess its sprouting regeneration process, we analyzed the number, length, and diameter of new shoots under different cutting treatments, and found significant differences based on various cutting heights and different cutting times (April vs. October). We conclude that cutting measures which take advantage of this species’ robust sprout tillering can increase the biomass of this shrub and also can improve its canopy density and its forage properties for livestock grazing, with the added benefits of improved sand-fixing and prevention of wind erosion. 相似文献
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