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正负地形可通过源汇过程对水、土资源进行再分配,影响山区的人口分布。获取正负地形数据,运用6个指标和多元逐步回归法,分析贵州高原山区正负地形特征及其对人口分布的影响。研究表明：①贵州高原山区的正负地形结构异质性明显。蚕食度、深切度、平均粗糙度比、形状指标、匀度指数、破碎度的平均值分别为1.07、371m、1.01、3.40、325和3.34,表明正地形被负地形蚕食明显、切入深度大,正、负地形的粗糙度基本相当,正负地形景观斑块呈现形状不规则、面积不均匀的破碎状态。6个正负地形指标中,匀度指数的变异性最大,变异系数为90.43%;平均粗糙度比的变异性最小,变异系数为1.06%;②贵州高原山区的人口分布不均匀性突出。人口累积达到40%时,累积面积百分比为14%;人口累积达到80%时,累积面积百分比约为50%;③6个正负地形指标中,蚕食度和深切度是影响人口分布的主要因素。蚕食度与人口密度呈正相关关系,深切度与人口密度呈负相关关系。研究成果为研究地形条件的人口影响提供补充,并为贵州高原山区人-地关系协调和土地可持续管理提供参考。 相似文献
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本文介绍了数字化射线照相技术对轻物质进行判断的方法。经实践证明，该方法是合理和有效的，可大大增强对轻物质的识别能力，是一种非常可行的识别技术。 相似文献
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基于事件数据的雅鲁藏布江-布拉马普特拉河国际河流安全分析 总被引：3，自引：0，他引：3
雅鲁藏布江-布拉马普特拉河是我国重要的国际河流,近年的水电开发活动,使其日益成为国内外国际河流研究关注的热点。本文基于国际关系研究中常用的事件分析方法,在构建事件数据库的基础上,从事件类型、涉及国别、事件频率、影响程度四方面进行分析,结果表明：水资源分配问题是雅江流域主要问题;中国在雅江国际河流问题上与下游国家的联系主要以与印度或孟加拉国的双边联系为主;随着时间的推移,雅江冲突与合作事件的频率都表现出增加的趋势;雅江围绕国际河流的国际关系局势大致可分为4个阶段：60年代的平稳阶段、70年代的紧张阶段、80年代的沉寂阶段、90年代后的持续关注阶段。 相似文献
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黄河中游多沙粗沙区流域坡面水保措施变化特征 总被引：1，自引：0，他引：1
选用Landsat TM、环境星CCD、SPOT4 和资源三号卫星影像等多源地学数据,通过人机交互式解译和修订土地利用与梯田数据,提出用相邻图幅递进回归分析法消除NDVI时相差异后反演植被盖度,构建起退耕还林还草面积比例、植被盖度均值变化量和有效梯田累计保存面积比例3 个坡面特征变化指示参数后,运用综合聚类分析和多要素贡献率模型研究黄河中游多沙粗沙区的流域坡面水保措施变化特征。结果表明：（1） 1998-2010 年间研究区内流域坡面水保措施变化显著,平均退耕还林还草面积比例为5.55%,平均林草植被盖度均值增加20.63%,平均有效梯田累计保存面积比例达6.25%;（2） 多要素水保措施变化共同作用下的流域坡面变化特征主要有7 种类型,即植被盖度变化主导型、植被—土地变化主导型、土地—植被变化主导型、植被—梯田变化主导型、梯田—植被变化主导型、梯田面积变化主导型和多要素变化共同主导型;（3） 不同类型的空间分布存在一定的地貌背景差异,后续研究应结合流域坡面变化特征及其地貌格局来优化配置水保措施,并合理估计水沙模型模拟的敏感性参数。 相似文献
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In areas with topographic heterogeneity, land use change is spatially variable and influenced by climate, soil properties, and topography. To better understand this variability in the high-sediment region of the Loess Plateau in which soil loss is most severe and sediment diameter is larger than in other regions of the plateau, this study builds some indicators to identify the characteristics of land use change and then analyze the spatial variability as it is affected by climate, soil property, and topography. We build two indicators, a land use change intensity index and a vegetation change index, to characterize the intensity of land use change, and the degree of vegetation restoration, respectively. Based on a subsection mean method, the two indicators are then used to assess the spatial variability of land use change affected by climatic, edaphic, and topographic elements. The results indicate that: 1) Land use changed significantly in the period 1998–2010. The total area experiencing land use change was 42,302 km2, accounting for 22.57%of the study area. High-coverage grassland, other woodland, and forest increased significantly, while low-coverage grassland and farmland decreased in 2010 compared with 1998. 2) Land use change occurred primarily west of the Yellow River, between 35 and 38 degrees north latitude. The four transformation types, including(a) low-coverage grassland to medium-coverage grassland,(b) medium-coverage grassland to high-coverage grassland,(c) farmland to other woodland, and(d) farmland to medium-coverage grassland, were the primary types of land use change, together constituting 60% of the area experiencing land use change. 3) The spatial variability of land use change was significantly affected by properties of dryness/wetness, soil conditions and slope gradient. In general, land use changed dramatically in semi-arid regions, remained relativelystable in arid regions, changed significantly in clay-rich soil, remained relatively stable in clay-poor soil, changed dramatically in steeper slopes, and remained relatively stable in tablelands and low-lying regions. The increase in vegetation coincided with increasing changes in land use for each physical element. These findings allow for an evaluation of the effect of the Grain to Green Program, and are applicable to the design of soil and water conservation projects on the Loess Plateau of China. 相似文献
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The objective of this study is to quantitatively evaluate Tropical Rainfall Measuring Mission(TRMM) data with rain gauge data and further to use this TRMM data to drive a Distributed Time-Variant Gain Model(DTVGM) to perform hydrological simulations in the semi-humid Weihe River catchment in China.Before the simulations,a comparison with a10-year(2001-2010)daily rain gauge data set reveals that,at daily time step,TRMM rainfall data are better at capturing rain occurrence and mean values than rainfall extremes.On a monthly time scale,good linear relationships between TRMM and rain gauge rainfall data are found,with determination coefficients R~2 varying between 0.78 and 0.89 for the individual stations.Subsequent simulation results of seven years(2001-2007)of data on daily hydrological processes confirm that the DTVGM when calibrated by rain gauge data performs better than when calibrated by TRMM data,but the performance of the simulation driven by TRMM data is better than that driven by gauge data on a monthly time scale.The results thus suggest that TRMM rainfall data are more suitable for monthly streamflow simulation in the study area,and that,when the effects of recalibration and the results for water balance components are also taken into account,the TRMM 3B42-V7 product has the potential to perform well in similar basins. 相似文献
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基于循环经济的黑龙江省耕地利用集约度时空差异 总被引：8，自引：0，他引：8
为准确把握耕地集约利用水平及时空变化特征,基于循环经济"减量化、再利用、资源化"的基本原则,从投入强度、重复利用、综合效益和持续状态入手构建耕地集约利用评价指标体系,采用熵值法和变异系数法对1986-2008年黑龙江省耕地利用集约度进行评价,并通过秩相关系数模型和聚类分析法分析黑龙江省各地耕地集约利用空间差异特征。结果表明:1研究期间黑龙江省耕地集约利用水平明显提高,但1994-1998年呈波动下降趋势;2除持续状态呈下降趋势外,其余准则层均表现为上升态势,耕地利用协调度处于高度协调状态;3黑龙江省东北部地区耕地利用集约度明显下降,其余地区耕地利用集约度的上升或下降幅度均不明显;4黑龙江省各地耕地利用集约度差异比较显著。 相似文献
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射线透射成像中重物质遮挡下的轻物质检测技术研究 总被引：2，自引：2，他引：0
本文研究了不同厚度轻重物质在射线透射成像中的图像灰度关系，根据提取轻物质轮廓线的要求，找出了在不同厚度重物质遮挡下的可检测出轻物质的最小厚度曲线。 相似文献
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