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Norbert Simon Michael Crozier Mairead de Roiste Abdul Ghani Rafek Rodeano Roslee 《Singapore journal of tropical geography》2015,36(1):98-111
This study assesses the influence of development on landslide occurrences in a rapidly developing area, Kota Kinabalu in Sabah Malaysia, across three assessment years (1978, 1994 and 2010). Two development indicators, land use and road density, were used to measure the influence of development on landslide occurrence. Land use was classified into four categories (barren, forest, developed and other), and road density was classified into low (< 50 m/40 000 m2), moderate (50–150 m/40 000 m2) and high (> 150 m/40 000 m2). Landslide density analysis was used to calculate the concentration of landslide for the different land use and road density categories. The number of landslides in developed areas increased from 19 landslides/100 km2 in 1978, to 29 landslides/100 km2 in 1994 and to 50 landslides/100 km2 in 2010, mirroring an increase in land use for development purposes from 8 per cent in 1978 to 27 per cent in 2010. Landslide density also gradually increased in the high road density class from 10 landslides/100 km2 in 1978, to 30 landslides/100 km2 in 1994 and 62 landslides/100 km2 in 2010. These results show that road construction activities influence landslide occurrences. 相似文献
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人口空间分布的规律及变动趋势对城市空间结构产生重要影响,是城市规划及政策制定的重要依据。在密度函数的基础上,构建新的计量模型,刻画了北京都市区人口增长的空间特征及趋势,并探讨了背后的机理。研究发现,2000-2010年北京都市区人口以集聚为主,北郊和远郊的人口先后呈现快速增长的格局。在中心区人口虽然实现了增长,但密度峰值不断降低,表现出均衡化的发展态势。1984-2010年模型拟合结果显示,随着到中心区距离的增加,人口发展速度呈现出先增后降的倒"U"型。与1984-2005年拟合结果比较发现,2005年以来远郊区人口整体发展速度大幅上升,近郊区平均增长速度也有小幅提升,而中心区人口整体增长速度进一步放缓,倒"U"型格局向线性递增格局演变,显示远郊逐步成为北京人口承载的主体空间。北京市人口增长的空间规律既体现了首都经济快速发展产生的人口集聚作用,也与西北部山区的生态环境建设、中心区旧城保护以及功能疏解等政策密切相关。政策启示是进一步提升远郊服务配套水平,增加就业岗位,建设功能混合、居住—就业—消费平衡的新城,增强人口吸引力。 相似文献
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基于Google earth的城市人口密度研究——以广东清远为例 总被引：1，自引：1，他引：0
引入Google Earth软件,讨论了一种快速、免费、便捷的研究城市人口密度的方法,该思路与方法在缺乏基础资料(如城市地形图、研究区域人口等数据)时能够作为一种有效的分析手段。文中通过获取各类地物信息,将土地利用、道路、建筑物等因素与人口密度建立起对应关系,绘制出研究区域的人口密度分布图,并对人口密度进行分析。此外,根据城市人口分布现状,提出人口引导控制区概念,为城市规划建设、环境保护等提供参考。 相似文献
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提出一种基于FCD数据的城市有效路网密度的评价方法,主要是从城市路网的静态布局结构和动态交通流量两个方面对城市路网数据以及FCD数据进行核密度估计分析,得到城市有效路网密度等级的分布特征,继而通过理论与实际道路网密度等级差异对比分析,发现路网中差异区域,为城市路网规划提供可靠的依据。以广州市中心城区越秀、荔湾内的主要路网数据以及2010年五一期间中心城区内出租车的FCD数据为例,利用上述评价方法进行分析得出以下结论:区域内人民中路、人民南路、白云路、中山六路和中山七路路段的理论与实际密度等级差异性明显,表现为路段上密度核的数量与核影响范围差异大,其中尤为突出的是人民中路和人民南路,从理论有效路网密度的分析角度,两个路段都是高密度区域,与实际交通流量存在较大的密度分异。 相似文献
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This paper demonstrates the plausibility of inferring the spatial variability of geology from topographically derived landscape dissection patterns. This enables surveying large regions for spatial variability in geology, for which direct remote sensing is not feasible, by studying variability in dissection pattern, a feature extracted straight off from digital elevation model data. Dissection pattern is obtained automatically by a novel algorithm, especially designed to delineate the valleys with high accuracy in order to reflect spatial variability in dissection density. The dissection pattern is encapsulated by a continuous map of drainage density, a raster variable best suited for showing spatial variability of dissection. Such a map, constructed for the study area in the Cascade Range, Oregon, USA, shows a sharp discontinuity in the dissection pattern, indicating change in underlying geology. Possible factors controlling the dissection pattern such as climate, local and regional slopes, vegetation, and geology are examined, and geology has been found to be the dominant controlling factor. The dissection contrast coincides with the boundary between the Western and High Cascades, two geologic provinces with different rock ages and types. The older and less permeable Western Cascades are associated with denser dissection pattern, whereas the younger and more permeable High Cascades correspond to less dissected pattern. This new mapping method can be applied to locations where topography is the only readily available data, and the generated map could be used to extract previously unknown geologic or environmental information. 相似文献
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Ground snow observation data from 1999 to 2008 were used to analyze the temporal and spatial distribution of snow density in
China. The monthly maximum density shifted from north to south during the period from October to the following January, and
then moved back from south to north during the period from January to April. The maximum snow density occurred at the border
between Hunan and Jiangxi provinces in January, where snow cover duration was short and varied remarkably. Snow density in
Northeast China and the Xinjiang Uygur Autonomous Region were also high and showed less variation when the snow cover duration
was long. Ground observation data from nine weather stations were selected to study changes of snow density in Northeast
and Northwest China. A phase of stable snow density occurred from the middle ten days of November to the following February;
non-stationary density phases were observed from October to the first ten days of November and from March to April. To further
investigate the effects of climatic factors on snow density, correlations between snow density and precipitation, air temperature,
snow depth and wind velocity for Northeast and Northwest China were analyzed. Correlation analysis showed that snow depth was
the primary influence on snow density. 相似文献
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流域地貌演化的不同阶段沟壑密度与切割深度关系研究 总被引：9，自引：3，他引：6
主要探讨了在流域地貌演化的不同阶段,沟壑密度与切割深度的复杂关系,建立了沟壑密度随切割深度变化的理论极值模型及相应阶段的函数,补充了各演化阶段地貌形态要素的定量、定性描述;反之,可用沟壑密度与切割深度的关系推断流域地貌的演化阶段。 相似文献
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Jay Lee Junfang Gong 《International journal of geographical information science》2017,31(6):1154-1177
We examined three different ways to integrate spatial and temporal data in kernel density estimation methods (KDE) to identify space–time clusters of geographic events. Spatial data and time data are typically measured in different units along respective dimensions. Therefore, spatial KDE methods require special extensions when incorporating temporal data to detect spatiotemporal clusters of geographical event. In addition to a real-world data set, we applied the proposed methods to simulated data that were generated through random and normal processes to compare results of different kernel functions. The comparison is based on hit rates and values of a compactness index with considerations of both spatial and temporal attributes of the data. The results show that the spatiotemporal KDE (STKDE) can reach higher hit rates while keeping identified hotspots compact. The implementation of these STKDE methods is tested using the 2012 crime event data in Akron, Ohio, as an example. The results show that STKDE methods reveal new perspectives from the data that go beyond what can be extracted by using the conventional spatial KDE. 相似文献
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Jordi Julià 《Geophysical Journal International》2007,171(1):286-301
This paper investigates the ability of P -wave receiver functions to constrain both the velocity and density contrasts across the Moho. Expressions for receiver function amplitudes corresponding to a layer over a half-space are extended to media with depth-dependent properties by explicitly accounting for free-surface reflection coefficients. Forward numerical computations show that receiver function amplitudes become frequency-dependent for depth-dependent structures and that, for a given frequency, wavelengths associated to Ps converted phases are larger than wavelengths associated to multiply reverberated phases. When consistent measurements of the amplitudes of Ps phase and multiples can be obtained, the extended expressions suffice to account for the observed amplitudes. Receiver function amplitudes are sensitive to both velocity and density contrasts across the Moho, and a two-step grid-search procedure is proposed to recover the contrasts from their measurement. The near-surface velocity is recovered in the first step from the amplitude of the direct P wave and then used in the second step to work out the relative density and S -wave velocity contrast from the amplitude of the secondary phases. Examples from central Spain (PAB) and the Indian Shield (HYB) are discussed and demonstrate that receiver function amplitudes can constrain contrasts across the Moho accurately enough to be utilized in geological interpretation. 相似文献
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1990年以来东北地区铁路运输的空间极化 总被引：11，自引：0，他引：11
以运输区段为研究单元, 以区段客流密度、货流密度、区段长度为原始数据, 将1990 年、1994 年、1999 年、2000 年和2005 年的东北地区铁路运输区段划分加以统一。首先运用 GIS 技术分析铁路运输密度变化的空间特征; 然后通过计算基尼系数、泰尔指数、集中指数 和崔王指数, 分析各年度铁路客货流分布的空间差异和极化程度;最后比较哈大线、沈山线 和滨洲－滨绥线等铁路干线的客货运周转量及比重变化。研究表明： ① 20 世纪90 年代铁路客流的空间极化比较明显, 2000 年以后极化趋势变缓或有所逆转; ② 货流在上行方向(向中部哈大线方向、向南部关内方向) 有趋于极化的特征; ③ 不管客流分布的总体特征向极化或分散方向如何变化, 哈大线在东北铁路网中的地位都在持续加强, 哈大线以外地区客流分布 趋向均衡。1990 年以来东北铁路运输分布的变化支持这样的区域空间极化过程： 向哈大沿线 集聚; 东北地区地域系统的层级减少, 哈大轴带作为顶层结构对整个东北地区的控制范围和程度增加。东北地区铁路网的整体性和区域一体化程度加深。 相似文献
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极端干旱环境下的胡杨细根分布与土壤特征 总被引：5，自引：2，他引：3
以塔里木河下游的中龄胡杨为研究对象,采用开挖剖面分层取样法,对胡杨细根(D≤2 mm)的空间分布以及与土壤特征因子之间的关系进行了分析。结果表明:①在长期干旱胁迫下,胡杨细根(D≤2 mm)根长密度(RLD)、根表面积密度(SAD)从表层到地下100 cm土层内,呈逐渐增加趋势,100~140 cm土层内表现为减少的波动分布趋势;细根RLD、SAD集中分布在60~120 cm土层内,约占0~140 cm土层总细根RLD和SAD的74%以上;在水平方向上,距树干0.75～2.5 m范围内,呈逐渐减少趋势,而在3.5～5.5 m范围内呈波动的增加趋势。②胡杨细根(D≤2 mm)RLD和SAD与土壤总盐、土壤有效养分含量之间呈显著负相关关系,适合乘幂模型,与土壤含水率之间呈一定程度的正相关关系,适合三次曲线模型。 相似文献
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以木兰围场国有林场管理局实施间伐后6种保留密度下（540、650、1 084、1 104、1 408和1 860 株 / hm2）油松人工林为研究对象,研究各土层的土壤有机碳和N、P、K等养分元素含量及其相关关系。研究结果显示：(1) 土壤有机碳含量和碳密度垂直递减特征明显,均随土壤深度的增加而显著减小,当林分密度由540 株 / hm2增加到1 860 株 / hm2时,土壤有机碳含量及碳密度变化规律不尽一致,其分布区间分别为10.56~21.21 g / kg,与5.48~11.70 kg / m2;(2) 林分密度对土壤有机碳及碳密度有显著的影响,1 408 株 / hm2油松林下土壤有机碳含量及碳密度分别与650 株 / hm2和1 860 株 / hm2油松林下土壤有机碳含量及碳密度呈显著性差异,而其它林分密度间无显著差异。当林分密度为1 104 株 / hm2时,各土层土壤全N和P、K的有效量及全量均保持在一个相对较高的水平,在0~60 cm深度土壤全N、全P、全K、有效P和速效K含量均值均达到最高,分别为1.38 g/kg、0.34 g/kg、32.75 g/kg、33.10 mg/kg和118.85 mg/kg;(3) 不同林分密度、不同土层土壤有机碳含量、碳密度与土壤全N及P、K的全量和有效量的相关显著性有差异,对整个土壤剖面而言,土壤有机碳含量及碳密度与土壤全N、全P、速效K均呈显著或极显著正相关;(4) 在本研究林分密度范围内,从林地土壤固碳的角度,建议将油松人工林的林分密度控制在1 104 株 / hm2。 相似文献
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Relationships among conductivity, temperature, total dissolved solids (TDS), and density were determined for hypersaline brine (TDS, 83 g kg–) from Mono Lake. A theoretical estimate of density based on ionic composition and calculated partial molar volumes compared well with actual measurements (difference, 390 ppm). However, an empirically derived equation of state based on temperature and conductivity provides the most accurate density estimates (residual errors, 190 ppm) and can be used with data collected with CTD profilers. 相似文献
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Discontinuity20.
一种基于数学形态学的沟壑密度提取算法 总被引：5，自引：0，他引：5
沟壑密度是反映地表破碎程度的重要因子 ,在土壤侵蚀、地貌演变等研究中有重要作用。本文介绍基于数学形态学的沟壑密度提取算法 ,从TM影像中提取沟谷线信息 ,从而有效地解决了土壤侵蚀评价中下垫面表征因子提取问题。并以黄河流域某小流域沟壑密度的计算作了实例验证。 相似文献