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111.
Theoretical difficulties for mapping and for estimating river regime characteristics in a large-scale basin remain because of the nature of the variable under study: river flows are related to a specific area, i.e. the drainage basin, and are hierarchically organized in space through the river network with upstream-downstream dependencies. Another limitation is there are not enough gauge stations in developing countries. This presentation aims at de-veloping the hydro-stochastic approach for producing choropleth maps of average annual runoff and computing mean discharge along the main river network for a large-scale basin. The approach applied to mean annual runoff is based on geostatistical interpolation proce-dures coupled with water balance and data uncertainty analyses. It is proved by an applica-tion in the upstream at Bengbu in the Huaihe River Basin, a typical large-scale basin in China. Hydro-stochasitic approach in a first step interpolates to a regular grid net and in a second step the grid values are integrated along rivers. The interpolation scheme includes a con-straint to be able to account for the lateral water balance along the rivers. Grid runoff map with 10 km × 10 km resolution and the discharge map along the river with the 1 km basic length unit are the main results in this study. This kind of statistic approach can be widely used be-cause it avoids the complexity of hydrological models and does not depend on the meteoro-logical data. 相似文献
112.
In order to improve the engineering stability of saline soil of high chloride content in the Chaerhan salt lake region, six typical characteristics saline soil samples were selected, and tests on their... 相似文献
113.
黄河下游泥沙淤积的经验统计关系 总被引:4,自引:0,他引:4
以黄河下游历年实测水文泥沙资料为基础,运用多元回归分析方法,建立了下游河道淤积量与淤积强度的经验统计关系。揭示了不同粒径组泥沙的来量和它们在全沙中所占的比率对下游河道淤积特征的影响。同时,研究了高含沙洪水及清水基流对下游河道淤积的影响。 相似文献
114.
玉龙铜(钼)矿带的成因机制和动力学背景一直存在争议。本文选择目前研究程度较低的多霞松多岩体, 对该岩体含矿斑岩开展岩相学、年代学、岩石地球化学及锆石Hf同位素分析。研究表明, 多霞松多岩体主要由二长花岗斑岩和碱长花岗斑岩组成, 其中, 二长花岗斑岩的主要造岩矿物为钾长石、斜长石和石英, 碱长花岗斑岩的主要造岩矿物为钾长石和石英。两种岩石属于高钾钙碱性-钾玄质侵入岩, 具有富碱高钾的特征; 亏损Nb、Ti等高场强元素, 富集Rb、Th、U等大离子亲石元素和Pb; 稀土元素含量较高(ΣREE=145.04×10-6~290.91×10-6), 富集轻稀土(LREE/HREE=6~37)。铕表现为从二长花岗斑岩的弱负异常(Eu/Eu*=0.66~0.84)到碱长花岗斑岩的中等负异常(Eu/Eu*=0.35~0.39)。锆石U-Pb定年显示, 二长花岗斑岩的成岩年龄为38.3±0.6 Ma, 碱长花岗斑岩的成岩年龄为37.8±1.0 Ma, 两者形成时代基本一致, 均属于喜马拉雅期, 表明在多霞松多地区始新世存在一期重要的岩浆热液Cu-Mo成矿事件。多霞松多含矿斑岩的锆石εHf(t)范围在+1.3~+2.6之间。结合元素和同位素地球化学特征, 指示多霞松多含矿斑岩可能来源于亏损地幔分异的新生玄武质下地壳, 受控于印度板块与欧亚板块碰撞诱发的金沙江走滑断裂系统。
相似文献115.
基于空间杜宾模型的中国高学历人才时空分异研究 总被引:1,自引:0,他引:1
基于2001~2016年全国统计年鉴数据,采用集聚度分析和空间自相关分析等方法,描绘中国高学历人才的空间格局及变化,并采用空间杜宾模型,探究影响高学历人才空间分布的主要因素及空间溢出效应。结果表明:(1)中国人才分布表现出较大的非均衡性,集聚程度表现为东南高、西北低,且2000~2015年间,人才稀疏区面积下降而集聚区面积上升;(2)中国人才密度的全局莫兰指数为正,表明中国的高学历人才分布具有一定的空间集聚特征,而2000~2015年此指数有所下降,表明人才分布整体上有分散趋势。2000年热点区与次级热点区主要分布于京津冀和长三角地区,其中热点区为京、津、沪;而2015年,热点以及冷点区域均有所扩张,表明局部地区人才仍然有集中化的趋势;(3)工资水平、高校发展、公共服务水平是决定人才空间分布的主要因素,但没有证据表明生活支出比、失业率、房价有显著影响。人才分布具有明显的空间溢出效应,同时工资水平、高校发展、公共服务水平等影响因素也具有明显的空间溢出效应。 相似文献
116.
W. C. Zhu C. H. Wei J. Liu T. Xu D. Elsworth 《Rock Mechanics and Rock Engineering》2013,46(6):1353-1366
It has been widely reported that coal permeability can change from reduction to enhancement due to gas adsorption even under the constant effective stress condition, which is apparently inconsistent with the classic theoretical solutions. This study addresses this inconsistency through explicit simulations of the dynamic interactions between coal matrix swelling/shrinking induced damage and fracture aperture alteration, and translations of these interactions to permeability evolution under the constant effective stress condition. We develop a coupled coal–gas interaction model that incorporates the material heterogeneity and damage evolution of coal, which allows us to couple the progressive development of damage zone with gas adsorption processes within the coal matrix. For the case of constant effective stress, coal permeability changes from reduction to enhancement while the damage zone within the coal matrix develops from the fracture wall to further inside the matrix. As the peak Langmuir strain is approached, the decrease of permeability halts and permeability increases with pressure. The transition of permeability reduction to permeability enhancement during gas adsorption, which may be closely related to the damage zone development in coal matrix, is controlled by coal heterogeneity, external boundary condition, and adsorption-induced swelling. 相似文献
117.
Dust sediments collected from 1995 to 1998 in Beijing, Dunhuang, Inner Mongolia, Kashi, the Kunlun Mountains, Lanzhou, Ningxia, the Taklimakan Desert, and Xi‘an, China, were characterized in terms of their physical, chemical, and mineralogical properties. Most aerosols and dust analysed ranged in texture from silty clay to clay loam. Their median particle diameters (Mds) generally ranged between 5 to 63μm,coinciding with those of loess from central China and the finest sand from northwestern China. The dust sediments were characterized by a predominance of SiO2 and Al2O3, followed by K2O. Their SiO2/Al2O3and K2O/SiO2 molar ratios ranged from 5.17 to 8.43 and from 0.009 to 0.0368, respectively. The mass concentration spectrum during a dust storm showed a single peak, rather than the triple peak generally observed under clear sky conditions. The dominant minerals were chlorite, illite, calcite, and dolomite.These physical, chemical, and mineralogical properties were consistent with those of aeolian soils and loess in western and central China. The results suggest that aerosols and fine-gained fractions of dust sediments collected in northern China are mainly composed of soil material transported from the arid and semiarid regions of China and Mongolia by prevailing winds. The rate of deposition and properties of dust falling on eastern China were strongly influenced by meteorological conditions, season, latitude, longitude, and altitude of the sampling sites. 相似文献
118.
Debasish Chakraborty Gautam Kumar Sen Sugata Hazra 《Journal of Earth System Science》2009,118(5):609-617
Texture in high-resolution satellite images requires substantial amendment in the conventional segmentation algorithms. A measure is proposed to compute the Hölder exponent (HE) to assess the roughness or smoothness around each pixel of the image. The localized singularity information is incorporated in computing the HE. An optimum window size is evaluated so that HE reacts to localized singularity. A two-step iterative procedure for clustering the transformed HE image is adapted to identify the range of HE, densely occupied in the kernel and to partition Hölder exponents into a cluster that matches with the range. Hölder exponent values (noise or not associated with the other cluster) are clubbed to a nearest possible cluster using the local maximum likelihood analysis. 相似文献
119.
广州城市居民地方依恋测度与机理 总被引:3,自引:0,他引:3
“地方依恋”问题涉及地理学、心理学、社会学、城市学等多个学科,已经成为中国快速城市化时期亟待解决的重要问题。伴随大城市内部空间的剧烈重构,城市居民对其居住空间的地方依恋也在不断变化,需要进行深入研究。本文选取广州23个典型社区,通过量表测度居民的地方依恋,并采用结构方程模型等计量方法,探索社区信任、社区满意度等要素对居民地方依恋的作用机理。同时,系统对比了居民对于不同空间尺度的地方依恋,如社区尺度和城市尺度,并对本地居民和外来移民两组人群的地方依恋及其差异进行了系统研究。研究发现:① 城市居民的社区依恋程度高于城市依恋程度;② 本地居民的社区依恋和城市依恋程度均明显高于外来移民;③ 城市居民的社区依恋同时受到社区信任和社区满意度的直接影响,但两者需通过社区依恋的中介效应间接影响居民的城市依恋;④ 社区信任与社区满意度对外来移民的社区依恋和城市依恋均具有显著作用,但对本地居民的城市依恋作用较弱。基于实证结果,本文认为,相同因素对于不同尺度的地方依恋作用机理存在差异,不同人群的地方依恋机理亦有不同,地方依恋同时具有尺度差异性和群体差异性。 相似文献
120.
Tamarix nabkha is one of the most widespread nabkhas,distributing in the arid region of China.Based on the observations outdoors and the simulation experiments in laboratories,analysis in this paper refers to the biological geomorphologic features and growth process of Tamarix nabkhas in the middle and lower reaches of the Hotan River,Xin- jiang.And the results indicate that the ecological type of Tamarix in the study area is a kind of Tugaic soil habitat based on the deep soil of the Populus Diversifolia f... 相似文献