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1.
《Urban geography》2013,34(2):263-300
Negative spatial autocorrelation (NSA), the tendency for dissimilar neighboring values to cluster on a map, may go undetected in statistical analyses of immature Anopheles gambiae s.l., a leading malaria mosquito vector in Sub-Saharan Africa. Unquantified NSA generated from an inverse variance-covariance matrix may generate misspecifications in an An. gambiae s.l. habitat model. In this research, we used an eigenfunction decomposition algorithm based on a modified geographic connectivity matrix to compute the Moran's I statistic, to uncover hidden NSA in a dataset of georeferenced An. gambiae s.l. habitat explanatory predictor variables spatiotemporally sampled in Malindi and Kisumu, Kenya. The Moran's I statistic was decomposed into orthogonal synthetic map patterns. Global tests revealed that |zMC|s generated were less than 1.11 for the presence of latent autocorrelation. The algorithm captured NSA in the An. gambiae s.l. habitat data by quantifying all non-normal random variables, space-time heterogeneity, and distributional properties of the spatial filters.  相似文献   

2.
The highly skewed sex ratio at birth (SRB) in China has stimulated numerous studies. However, the geographic distribution of SRB is seldom investigated, particularly at the county level. The need for an understanding at this level has increased since the Chinese government initiated its ‘Care for Girls’ campaign to improve the survival rate of females. This campaign has been initiated in a set of pilot counties. In this article we assess the effectiveness of the set of pilot counties in Shandong province and propose two alternate configurations. To do this, we first assess the spatial distribution of the SRB values by county in Shandong, expressed as a z-score (zSRB) after correcting for the biologically expected SRB value and population size of zero-aged children. A local Moran's Ii analysis of the zSRB values indicates a significant high–high cluster in the southwest of the province. The Ii , zSRB and female deficit (the difference of the observed from biologically expected number of zero-aged females) were then used to define two alternate configurations for the pilot counties. A comparison of the current and alternate configurations against a Monte Carlo randomisation analysis shows that the current configuration is significantly different from a random selection (p < 0.05) for the two criteria of maximising the aggregate female deficit and maximising the zSRB. Although this is a good result, both alternate configurations were more significant (p < 0.001), and therefore represent potentially better configurations for the campaign given the criteria used. The spatial analysis approach developed here could be used to improve the effectiveness of the Care-for-Girls campaign in Shandong province, and elsewhere in China.  相似文献   

3.
The Gulf of Mexico experiences significant changes in the distribution of daily precipitation totals that are linked to the El Niño–Southern Oscillation (ENSO). This research uses geospatial techniques to examine distribution patterns of ENSO-related precipitation. Kolmogorov–Smirnov test results comparing daily rainfall distributions for El Niño and La Niña are mapped at a 1° × 1° latitude/longitude resolution, and hotspot analysis using local Moran's I is performed to identify spatial clustering. Results indicate that ENSO-forced spatial and temporal variation in daily precipitation distributions influence large areas of the Gulf of Mexico region from August through January.  相似文献   

4.
Spatial data can be represented at different scales, and this leads to the issue of multi-scale spatial representation. Multi-scale spatial representation has been widely applied to online mapping products (e.g., Google Maps and Yahoo Maps). However, in most current products, multi-scale representation can only be achieved through a series of maps at fixed scales, resulting in a discontinuity (i.e., with jumps) in the transformation between scales and a mismatch between the available scales and users' desired scales. Therefore, it is very desirable to achieve smoothly continuous multi-scale spatial representations. This article describes an integrated approach to build a hierarchical structure of a road network for continuous multi-scale representation purposes, especially continuous selective omission of roads in a network. In this hierarchical structure, the linear and areal hierarchies are constructed, respectively, using two existing approaches for the linear and areal patterns in a road network. Continuous multi-scale representation of a road network can be achieved by searching in these hierarchies. This approach is validated by applying it to two study areas, and the results are evaluated by both quantitative analysis with two measures (i.e., similarity and average connectivity) and visual inspection. Experimental results show that this integrated approach performs better than existing approaches, especially in terms of preservation of connectivity and patterns of a road network. With this approach, efficient and continuous multi-scale selective omission of road networks becomes feasible.  相似文献   

5.
The objective of this study is to provide an approach for assessing the short-term risk of mountain pine beetle Dendroctonus ponderosae Hopkins (Coleoptera: Scolytidae) attack over large forested areas based on the spatial-temporal behavior of beetle spread. This is accomplished by integrating GIS, aerial overview surveys, and local indicators of spatial association (LISA) in order to measure the spatial relationships of mountain pine beetle impacts from one year to the next. Specifically, we implement a LISA method called the bivariate local Moran's Ii to estimate the risk of mountain pine beetle attack across the pine distribution of British Columbia, Canada. The bivariate local Moran's Ii provides a means for classifying locations into separate qualitative risk categories that describe insect population dynamics from one year to the next, revealing where mountain pine beetle populations are most likely to increase, stay constant, or decline. The accuracy of the model's prediction of qualitative risk was higher in initial years and lower in later years of the study, ranging from 91% in 2002 to 72% in 2006. The risk rating can be continually updated by utilizing annual overview surveys, thus ensuring that risk prediction remains relatively high in the short-term. Such information can equip forest managers with the ability to allocate mitigation resources for responding to insect epidemics over very large areas.  相似文献   

6.
Calibration and validation of models predicting urban growth have been largely developed using internal variables. Further investigation is required to improve model’s calibration and validation mixing internal and external variables. To reach this objective, a spatial zoning approach simulating long-term expansion of Mashhad, the second largest city of Iran, was presented in this study. Spatial zoning approaches distinguish local-scale urban dynamics in districts with different socioeconomic characteristics. Thiessen polygons were used to identify districts with different morphology and functional attributes. Urban growth was subsequently simulated for each district using a Multi-Layer Perceptron (MLP) neural network and Markov chains (MC) analysis. MLP and MC algorithms were respectively used to derive transition maps from non-urban to urban use of land and to determine spatial evolution of built-up areas at the metropolitan scale. Results of simulations based on spatial zoning were compared with outcomes of traditional urban growth models. Spatial zoning improved significantly model’s accuracy in respect to more traditional simulation modes. The approach proposed here is appropriate when simulating land-use changes under discontinuous urban expansion.  相似文献   

7.
Potential death from traffic collisions is a common hazard faced by nearly everyone. This analysis uses geographical approaches to examine fatal collision risk in the state of Indiana from 2003 to 2011. The state averaged 757 fatal collisions annually. About 60 percent occurred in urban or suburban areas. Risk was highest in low-density exurban and rural areas and on highways, county roads, and interstates. County sheriffs and state police were more likely to face fatal collisions than municipal police. Significant black spots existed around the Illinois and Kentucky state lines. Fatal collisions were less clustered than nonfatal collisions. Fatal collisions exhibited positive spatial autocorrelation but the global Moran's I for counties was close to random. Approximately 10 percent of ninety-two counties had significant local spatial autocorrelation in fatal collision rates. Police and emergency response resource distributions should be considered in light of fatal collision black spots in the state.  相似文献   

8.
We present a geometric and graphic approach to studying spatial patterns of urban hierarchy in the US. The multiplicatively weighted Voronoi diagram is found to be effective for visualizing theoretical regions delineated by socio‐economic variables. The population landscape of the continental US demonstrates overall and stepwise patterns reflecting population, neighborhood and distance, with overwhelming influence from huge metropolitan areas. Stepwise exploration and cluster analysis of the spatial pattern reveal an urban hierarchy. Attributes and arrangement are the two important factors of urban hierarchy, with attribute having a stronger local influence and arrangement having a stronger global influence. The study also presents a variation of Zipf's law to visualize the rank‐size distribution from tabular and statistical space to map space.  相似文献   

9.
黄河下游沿岸地市CO2排放的时空分异   总被引：1，自引：0，他引：1  
张金萍  秦耀辰  张丽君  路超君 《地理研究》2012,31(12):2229-2239
地市级尺度的碳排放结构演变与区域差异分析对通过技术学习与知识流动短期内抑制 碳排放的快速增长具有重要意义。以地市级行政区作为基本空间单元, 对黄河下游沿岸区、 两大子区及21地市化石能源与水泥工业生产过程排放的CO2 进行科学核算, 发现CO2 排放量 变化于2000年的364.12～4426.95万t至2009年的1238.98～10411.91万t,呈现出典型的 “S型”增长特征, 但不同尺度区域排放结构的时空差异显着。2006年以来, 工业化进程较快 的区域水泥排碳比例有显着增长, 产业结构优化策略促使少数地市水泥排碳比例有所下降。 CO2 排放强度与人均排放量的变动符合碳排放EKC曲线关系, 但时空分异特征并不一致。排 放强度的全区总体差异较为合理, 而人均排放量的区域差异偏大, 从而为涓滴效应的加速作 用创造了空间。地区内差异分别为两指标全区总体差异变动的主导因素, 整体上, 中原区内 地市间差异对两指标全区差异变动的贡献更大。  相似文献   

10.
Scientific interpretation of the relationships between agricultural landscape patterns and urbanization is important for ecological planning and management. Ordinary least squares (OLS) regression is the primary statistical method in previous studies. However, this global regression lacks the ability to uncover some local-specific relationships and spatial autocorrelation in model residuals. This study employed geographically weighted regression (GWR) to examine the spatially varying relationships between several urbanization indicators (urbanization intensity index, distance to urban centers and distance to road) and changes in metrics describing agricultural landscape patterns (total area, patch density, perimeter area ratio distribution and aggregation index) at two block scales (5 km and 10 km). Results denoted that GWR was more powerful than OLS in interpreting relationships between agricultural landscape patterns and urbanization, since GWR was characterized by higher adjust R2, lower Akaike Information Criterion values and reduced spatial autocorrelations in model residuals. Character and strength of the relationships identified by GWR varied spatially. In addition, GWR results were scale-dependent and scale effects were particularly significant in three aspects: kernel bandwidth of weight determination, block scale of pattern analysis, and window size of local variance analysis. Homogeneity and heterogeneity in the relationships between agricultural landscape patterns and urbanization were subject to the coupled influences of the three scale effects. We argue that the spatially varying relationships between agricultural landscape patterns and urbanization are not accidental but nearly universal. This study demonstrated that GWR has the potential to provide references for ecological planners and managers to address agricultural landscapes issues at all scales.  相似文献   

11.
洞庭湖区生态承载力时空演化特征   总被引：4，自引：0，他引：4  
熊建新  彭保发  陈端吕 《地理研究》2013,32(11):2031-2040
利用探索性空间数据分析以及百分位数和变异系数,基于Arc GIS 和Geo DA软件支撑,对洞庭湖区生态承载力的空间格局特征、空间关联特征和相对差异演变特征进行分析。结果表明：① 空间格局上,洞庭湖区生态承载力从西南向东北大体上呈现“W”型（较高—低—高—低—较高）空间格局,倒“U”型的县域差异特征显著。② 空间关联上,洞庭湖区生态承载力的分布呈正的全局空间自相关,出现相似县域之间的空间集聚,全局Moran’s Ⅰ值相差不大,空间聚集程度比较稳定,趋于围绕某一偏低集聚度出现小范围内波动;局部空间自相关的LISA 集聚类型出现HH型、HL型和LH型3 种类型,依次集中分布在洞庭湖区的中部、西南部和东北部,局部空间格局保持相对稳定,但是聚类特征显现出稍微变化的迹象。③ 相对差异演变上,2001-2010 年洞庭湖区生态承载力相对差异演变整体上呈现一定的差异性。2001-2003 年相对差异较小,趋于稳定;2005 年前后相对差异较大;相比2001-2003 年,2005 年以来相对差异明显扩大且这种较大的空间相对差异随着时间的推移呈现小幅波动趋势。  相似文献   

12.
This paper investigates regional inequality and development in China's Guangdong province by employing the multi-scale and multi-mechanism framework. The study further examines the relationship between space, scale, and regional inequality by applying a spatial filtering method that eliminates spatial dependence of the data and quantifies the extent to which spatial effects have contributed to regional inequality at multiple scales. The results suggest that over 90% of the divide between the core of the Pearl River Delta (PRD) and the periphery areas of Guangdong province can be explained by the effect of strengthening spatial dependence. By incorporating spatial filters in space-time models, we also reveal the space-time and core-periphery heterogeneities of development mechanisms. Our study confirms that the integration of a multi-scale and multi-mechanism framework and rigorous spatial analysis methods, such as spatial filtering and space-time modeling, helps better understand the complexity of regional development in China.  相似文献   

13.
Spatial aggregations of raster data based on the majority rule have been typically used in landscape ecological studies. It is generally acknowledged that (1) dominant classes increase in abundance while minor classes decrease in abundance or even disappear through aggregation processes; and (2) spatial patterns also change with aggregations. In this paper, we examined an alternative, random rule-based aggregation and its effects on cover type abundance and landscape patterns, in comparison with the majority rule-based aggregation. We aggregated a classified TM imagery (about 1.5 million ha) from 30m (4231 × 3717 pixels) incrementally to 990m resolution (132 pixels × 116 pixels). Cover type proportion, mean patch size ratio, aggregation index (AI), and fractal dimension (FD) were used to assess the effects of aggregation. To compare landscapes under different resolutions, we assumed that the landscapes were least distorted if (1) the cover type proportions and mean patch size ratios among classes were maintained, and (2) all cover types responded in the same way for a given index as aggregation levels increased. For example, distortion is introduced by aggregation if some cover types increase their AI values with increasing aggregation levels while other cover types decrease. Our study indicated that the two spatial aggregation techniques led to different results in cover type proportions and they altered spatial pattern in opposite ways. The majority rule-based aggregations caused distortions of cover type proportions and spatial patterns. Generally, the majority rule-based aggregation filtered out minor classes and produced clumped landscapes. Such landscape representations are relatively easy for interpreting and, therefore, are suitable for land managers to conceptualize spatial patterns of a study region. By contrast, the random rule-based aggregations maintained cover type proportions accurately, but tended to make spatial patterns change toward disaggregation. Overall, the measurements of landscape indices used in this study indicated that  相似文献   

14.
功能分区视角下的西安市发展空间分异   总被引：2，自引：0，他引：2  
吴文恒  徐泽伟  杨新军 《地理研究》2012,31(12):2173-2184
有效的功能分区是城市系统健康有序发展的保障。本文构建评价指标体系, 采用系统 聚类分析方法, 在功能分区视角下将西安市九个辖区分为核心区、雁塔区、未央区、长安区、 灞桥区及临潼-阎良区六个功能区域。中心商务区主导下核心区商贸流通业发达, 高新技术 产业开发区与曲江文化产业示范区主导下雁塔区技术经济与文化产业特色鲜明, 经济技术开 发区主导下未央区工业经济特征明显, 郭杜教育科技产业开发区与国家民用航天产业基地强 化长安区科教文化发展方向, 浐灞生态区彰显灞桥区生态经济发展特色, 生态农业区、阎良 飞机城加快临潼、阎良两区传统农业发展转型。功能分区及发展空间分异是城市化与经济发 展、历史基础与路径依赖、规模经济与集聚效应、本底化与特色化等基础因子以及新经济与 开发区建设、宏观调控与政策导向等新型因子综合驱动的结果, 基础因子起缓慢影响与逐渐 推进的辅助作用, 新型因子起突变影响与直接推动的主导作用。研究有助于科学认识城市, 合理组织城市, 提供实践参考。  相似文献   

15.

An interest in culture developed in human geography from its beginning. It was rooted in a conception of 'geography as a science of places, not of men' (Vidal de la Blache), and focused on the study of man/milieu relationships through the analysis of landscapes or genres de vie , the origin and dispersal of agriculture, and the regional diversity of the earth. A neo-Weberian orientation appeared in the 1960s, but the main shift occurred in the 1970s, with the adoption of phenomenological or critical perspectives. The new cultural approach modernises the traditional orientations in the field, explores the meaning that people give to their spatial experience, and introduces new questions about the epistemological foundations of geography as a scientific discipline. In order to understand how society is produced and reproduced and how significance is given to the world, the new approach stresses the role of communication in cultural processes and spatial organisation.  相似文献   

16.
A regional ecological study is made of the structure of taiga landscapes as a natural background of Siberia's forest distribution. A lower forest-vegetation zoning is carried out using the landscape-ecological maps generated on a geomeric basis. The character of dynamical changes of taiga landscapes is considered, and their resistance assessed.  相似文献   

17.
旅游景区合理布局是实现黄河流域旅游业高质量发展的内在要求与根本保障,识别景区空间格局及其影响因素如何随尺度发生变化,对黄河流域的景区多层级统筹管理具有重要现实意义。基于地理因素的空间尺度效应,从县域、市域、集聚区3个尺度构建了分析框架,利用统计与GIS技术揭示黄河流域A级景区多尺度空间格局,运用地理探测器、空间叠加分析等揭示各尺度影响因素及其差异特征。结果表明:(1)黄河流域A级景区整体呈东部和南部密集、西部和北部稀疏的空间格局,流域南部形成一个中高密度弧形带。随着研究尺度增大,景区集聚范围逐渐扩大,集聚程度逐渐降低;(2)县域尺度上,全国重点文物保护单位密度对景区格局影响程度最大,其次是植被覆盖度、年降水量、到最近河流距离、国家湿地公园密度。人口密度是市域尺度影响程度最大的主导因素,非主导因素在与各主导因素交互后形成强烈的增强效应。集聚区尺度景区格局主要受年降水量、植被覆盖度等自然环境因素的刚性约束;(3)3个尺度的影响因素明显不同,不同尺度景区格局并不是主导因子简单组合或累积的结果,而是自然环境、旅游资源、社会经济及区位复杂交互后的产物。  相似文献   

18.
Moose–vehicle collisions (MVCs) pose a serious safety and environmental concern in many regions of Europe and North America. For example, in the state of Vermont, one‐third of all reported MVCs resulted in motorist injury or fatality while collisions have increased from two in 1982 to 164 in 2002. Our work used a MVC dataset from 1983 to 1999 in the Northeastern Highlands of Vermont (four major roads) to perform space, time and spatiotemporal analyses and guide future mitigation strategies. An adapted kernel density estimator was implemented for exploratory analyses to detect high density collision hotspots on roads. The kernel in space showed seven major density peaks which varied in magnitude and spread between roads. The kernel estimator in time for all roads showed an exponentially increasing trend with annual periodicity and a seasonal cyclic component, where the majority of collisions occurred from May to October. Spatiotemporal kernel estimation exhibited discontinuous density hotspots in time and space suggesting changing animal movement patterns across roads. We used an adapted Ripley's K‐function to test the hypothesis that MVCs clustering occurred at multiple scales in space, in time and in space–time combined. Statistically significant spatial clustering was evident on all roads at spatial scales from 2 to 10 km. A more consistent clustering in time occurred on all roads at a scale distance of 5 years. Similar to the kernel estimation, annual periodicity was also evident. Positive space–time clustering was present at small spatial (5 km) and temporal scales (2 years) indicating that where MVCs occur is also influenced by when they occur. In retrospect, using multiple road lengths, and the combined kernel estimation and Ripley's K‐function in time and space, provided a powerful methodology to study varying spatiotemporal patterns of wildlife collisions along roads. This can greatly assist transportation planners in identifying optimal mitigation strategies along specific roads, such as deciding on location and spatial length for permanent and expensive measures (e.g. crossing structures and associated fencing) versus less permanent and inexpensive structures (e.g. wildlife signage and reduced speed limits).  相似文献   

19.
都市圈是承载城市等级层次结构的重要空间集群,基于城市等级体系概念,为明确广东省城市等级结构以及在新型城镇化背景下优化都市圈建设,提出"城市发展综合度"指标体系,采用因子分析法,考察广东省21个地级市的综合发展程度。将这些地级市划分为核心城市、区域性中心城市、区域性次中心城市、地方性中心城市、地方性次中心城市和地方性一般城市6个等级层次。并且提出优化广东省都市圈发展的建议。  相似文献   

20.
Three samples of twenty drainage basins were analyzed to test the hypothesis that the generic terms “creeks,'’“runs,'’and “hollows'’connote streams of different size and velocity. Analysis of variance and Scheffé's test indicate the validity of a perceptual hierarchy among generics. It is suggested that other hierarchies may exist among geographically named features.  相似文献   

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