Spatiotemporal analysis of rural–urban land conversion     

Bo Huang  Li Zhang  Bo Wu 《International journal of geographical information science》2013,27(3):379-398

Understanding the complexity of urban expansion requires an analysis of the factors influencing the spatial and temporal processes of rural–urban land conversion. This study aims at building a statistical land conversion model to assist in understanding land use change patterns. Specifically, GIS coupled with a logistic regression model and exponential smoothing techniques is used for exploring the effects of various factors on land use change. These factors include population density, slope, proximity to roads, and surrounding land use, and their influence on land use change is studied for generating a predictive model. Methods to reduce spatial autocorrelation in a logistic regression framework are also discussed. Primarily, an optimal sampling scheme that can eliminate spatial autocorrelation while maintaining adequate samples to allow the model to achieve the comparable accuracy as the spatial autoregressive model is developed. Since many of the previous studies on modeling the spatial complexity of urban growth ignored temporal complexity, a modified exponential smoothing technique is employed to produce a smoothed model from a series of bi‐temporal models obtained from different time periods. The proposed model is validated using the multi‐temporal land use data in New Castle County, DE, USA. It is demonstrated that our approach provides an effective option for multi‐temporal land use change modeling and the modeling results help interpret the land use change patterns.  相似文献   

Geographical Detectors‐Based Health Risk Assessment and its Application in the Neural Tube Defects Study of the Heshun Region,China     

Jin‐Feng Wang  Xin‐Hu Li  George Christakos  Yi‐Lan Liao  Tin Zhang  Xue Gu 《International journal of geographical information science》2013,27(1):107-127

Physical environment, man‐made pollution, nutrition and their mutual interactions can be major causes of human diseases. These disease determinants have distinct spatial distributions across geographical units, so that their adequate study involves the investigation of the associated geographical strata. We propose four geographical detectors based on spatial variation analysis of the geographical strata to assess the environmental risks of health: the risk detector indicates where the risk areas are; the factor detector identifies factors that are responsible for the risk; the ecological detector discloses relative importance between the factors; and the interaction detector reveals whether the risk factors interact or lead to disease independently. In a real‐world study, the primary physical environment (watershed, lithozone and soil) was found to strongly control the neural tube defects (NTD) occurrences in the Heshun region (China). Basic nutrition (food) was found to be more important than man‐made pollution (chemical fertilizer) in the control of the spatial NTD pattern. Ancient materials released from geological faults and subsequently spread along slopes dramatically increase the NTD risk. These findings constitute valuable input to disease intervention strategies in the region of interest.  相似文献   

Morphometric characterisation of landform from DEMs     

Daming Wang  Shawn W. Laffan  Yu Liu  Lun Wu 《International journal of geographical information science》2013,27(2):305-326

We describe a method of morphometric characterisation of landform from digital elevation models (DEMs). The method is implemented first by classifying every location into morphometric classes based on the mathematical shape of a locally fitted quadratic surface and its positional relationship with the analysis window. Single‐scale fuzzy terrain indices of peakness, pitness, passness, ridgeness, and valleyness are then calculated based on the distance of the analysis location from the ideal cases. These can then be combined into multi‐scale terrain indices to summarise terrain information across different operational scales. The algorithm has four characteristics: (1) the ideal cases of different geomorphometric features are simply and clearly defined; (2) the output is spatially continuous to reflect the inherent fuzziness of geomorphometric features; (3) the output is easily combined into a multi‐scale index across a range of operational scales; and (4) the standard general morphometric parameters are quantified as the first and second order derivatives of the quadratic surface. An additional benefit of the quadratic surface is the derivation of the R ² goodness of fit statistic, which allows an assessment of both the reliability of the results and the complexity of the terrain. An application of the method using a test DEM indicates that the single‐ and multi‐scale terrain indices perform well when characterising the different geomorphometric features.  相似文献   

玉树地震滑坡分布调查及其特征与形成机制   总被引：2，自引：2，他引：0  

许冲  徐锡伟  于贵华 《中国地震研究》2013,27(1):1-22

On April 14, 2010 at 07:49 (Beijing time), a catastrophic earthquake with MS7.1 occurred at the central Qinghai-Tibetan Plateau. The epicenter was located at Yushu county, Qinghai Province, China. A total of 2036 landslides were determined from visual interpretation of aerial photographs and high resolution remote sensing images, and verified by selected field investigations. These landslides covered a total area of about 1.194km2. Characteristics and failure mechanisms of these landslides are listed in this paper, including the fact that the spatial distribution of these landslides is controlled by co-seismic main surface fault ruptures. Most of the landslides were small scale, causing rather less hazards, and often occurring close to each other. The landslides were of various types, including mainly disrupted landslides and rock falls in shallows and also deep-seated landslides, liquefaction induced landslides, and compound landslides. In addition to strong ground shaking, which is the direct landslide triggering factor, geological, topographical, and human activity also have impact on the occurrence of earthquake triggered landslides. In this paper, five types of failure mechanisms related to the landslides are presented, namely, the excavated toes of slopes accompanied by strong ground shaking; surface water infiltration accompanied by strong ground shaking; co-seismic fault slipping accompanied by strong ground shaking; only strong ground shaking; and delayed occurrence of landslides due to snow melt or rainfall infiltration at sites where slopes were weakened by co-seismic ground shaking. Besides the main co-seismic surface ruptures, slope fissures were also delineated from visual interpretation of aerial photographs in high resolution. A total of 4814 slope fissures, with a total length up to 77.1km, were finally mapped. These slope fissures are mainly distributed on the slopes located at the southeastern end of the main co-seismic surface rupture zone, an area subject to strong compression during the earthquake.  相似文献   

考虑地震构造背景的地震活动性参数光滑方法在地震危险性概率评价中的应用     

张力方  吕悦军  彭艳菊  马晓玲  崔满丰 《中国地震研究》2013,27(1):121-132

In this study, the North China seismic region was selected as the study area, and evaluation of seismic hazard using the spatial smoothing seismicity model was performed. Firstly, the study area is divided into grids, and some parameters (e.g. b-value, M0, Mu, azimuth and M-L relationship) for each seismotectonic model were assigned. Secondly, using elliptical smoothing based on a seismotectonic background model, the statistical earthquake incidence rate in each grid is successively calculated. Lastly, the relevant ground motion attenuation relationship is chosen to assess seismic hazard of general sites. The maps for the distribution of horizontal peak ground acceleration with 10% probability of exceedance in 50 years were obtained by using the seismic hazard analysis method based on grid source. This seismicity model simplifies the methodology of probabilistic seismic hazard analysis, especially appropriate for those places where seismic tectonics is not yet clearly known. This method can provide valuable references for seismic zonation and seismic safety assessment for significant engineering projects.  相似文献   

Vertical distribution of HTO and 125I− transport parameters in Boom Clay in the Essen-1 borehole (Mol,Belgium)     

《Physics and Chemistry of the Earth》2013

In the frame of the R&D activities performed on the Boom Clay for assessing the suitability of deep clayey formations for radioactive waste disposal, the transferability of the scientific results obtained on the Boom Clay in Mol to the whole Campine Basin is investigated. Boreholes were drilled at different locations (e.g. Mol, Doel, Essen) and cores were sampled over the entire thickness of the Boom Clay formation on which the migration parameters for iodide and tritiated water (HTO) are determined.At Essen, the transport parameters in the Boom Clay can be considered as homogeneous in the range from 159 m to 241 m Below Drilling Table. The average hydraulic conductivity is (5.4 ± 1.7) × 10⁻¹² m/s. The average ηR value for iodide is 0.25 ± 0.03 and 0.42 ± 0.05 for HTO. For HTO, this high value is mainly due to a higher value in the Putte Member (0.46 ± 0.03) compared to the other members (0.39 ± 0.02). The apparent diffusion coefficient is (1.3 ± 0.1) × 10⁻¹⁰ m²/s for HTO and (1.1 ± 0.2) × 10⁻¹⁰ m²/s for iodide. The expected effect of ionic strength (increasing with depth) on the ηR value of iodide is of the same size as the measurement error, what might explain why it was not observed.On a lateral (horizontal) level, the hydraulic conductivity at the Essen-1 borehole (5.4 × 10⁻¹² m/s) lies between that of Boom Clay in Mol-1 (2.5 × 10⁻¹² m/s) and that of Boom Clay in Doel-2b (1.4 × 10⁻¹¹ m/s). For iodide, the higher ηR value in Essen-1 and Doel-2b (ηR ≈ 0.25) than in Mol-1 (ηR ≈ 0.16) can partly be explained by a higher ionic strength of the pore water. Apart from the Putte Member at Essen-1, the HTO porosities of the Terhagen Member and the Transition zone in Essen are in the range of the average porosities observed in Mol and Doel (ηR ≈ 0.37–0.39). For both iodide and HTO, the value of the apparent diffusion coefficient D_app is similar in Mol-1 and in Doel-2b, with a clearly higher value for HTO than for iodide. In Essen-1, the apparent diffusion coefficients for iodide and HTO are nearly equal, and slightly smaller than the iodide value in Mol-1/Doel-2b. Accordingly, the HTO apparent diffusion coefficient is considerably smaller in Essen-1 than in Mol-1/Doel-2b.  相似文献   

Incorporating spatial association into statistical classifiers: local pattern-based prior tuning     

Hexiang Bai  Feng Cao  M. Peter Atkinson  Qian Chen  Jinfeng Wang 《International journal of geographical information science》2020,34(10):2077-2114

ABSTRACT

This paper proposes a new classification method for spatial data by adjusting prior class probabilities according to local spatial patterns. First, the proposed method uses a classical statistical classifier to model training data. Second, the prior class probabilities are estimated according to the local spatial pattern and the classifier for each unseen object is adapted using the estimated prior probability. Finally, each unseen object is classified using its adapted classifier. Because the new method can be coupled with both generative and discriminant statistical classifiers, it performs generally more accurately than other methods for a variety of different spatial datasets. Experimental results show that this method has a lower prediction error than statistical classifiers that take no spatial information into account. Moreover, in the experiments, the new method also outperforms spatial auto-logistic regression and Markov random field-based methods when an appropriate estimate of local prior class distribution is used.  相似文献   

闽粤赣三角地带典型客家民居及其旅游地的空间竞争   总被引：1，自引：0，他引：1  

罗迎新 《热带地理》2010,30(3)

实证应用分析研究表明,根在中原的客家人因客居地区不同,其民居建筑因地而异;地处闽粤赣三角地带的客家民居,以永定的土楼、梅州的围龙屋和赣南的围屋,并称客家三大典型代表性民居,其造型规模和建筑艺术渊源来自北方中原的建筑造型艺术和夯土技术,建筑形态以方形、圆形为主,强调中轴对称位置,土楼、围屋的防卫功能突出,围龙屋的开放功能显著。应用旅游地空间竞争理论分析了影响闽粤赣三角地带典型客家民居旅游地空间竞争的因素,认为客家民居旅游地的空间竞争是同类型非替代性竞争。同时,提出了客家民居旅游开发要以保护为前提、加强区域合作与规划、资源互补与联动发展的开发策略。  相似文献   

滇西北区域旅游竞争视角下的怒江州旅游产品创新设计研究   总被引：2，自引：0，他引：2  

董培海  李伟 《云南地理环境研究》2010,22(1):100-104,110

通过评述滇西北旅游业发展的总体概况,重新剖析了怒江州旅游资源特征。对该区域几大旅游目的地旅游景观、旅游产品以及旅游市场进行比较,认为滇西北旅游业发展呈替代性竞争的态势。最终将落脚点放到怒江这个滇西北各旅游目的地中的"后起之秀"上,提出旅游产品创新是怒江旅游业发展的关键。并从"高起点、大手笔打造观光型旅游产品;全方位、多角度开拓主题园区型旅游产品;深层次、宽领域挖掘民族文化体验型旅游产品"这3个方面具体对怒江旅游产品类型进行构思与设计。  相似文献   

浑善达克沙地天然沙地榆种内竞争研究     

昭日格  李钢铁  岳永杰  邹受益 《中国沙漠》2011,31(2):451-455

采用逐步扩大范围的方法确定影响沙地榆对象木的最佳竞争范围,利用Hegyi提出的单木竞争指数模型,对浑善达克沙地天然沙地榆种内竞争强度进行定量分析。结果表明,在沙地榆群落中,对象木的最佳竞争距离为8 m,沙地榆种内竞争强度随着植株径级的增大而逐渐减小。竞争强度与对象木胸径服从幂函数关系,从模型预测结果可知,当沙地榆胸径在30 cm以内时,竞争强度变化显著;当沙地榆胸径达30 cm 以上时,竞争强度变化很小。采用逐步扩大范围的方法能有效地确定竞争木范围,较好地反应浑善达克沙地天然沙地榆种内竞争关系。应在沙地榆胸径达30 cm前采取适当的人工疏伐措施来促进植株生长和增强生态系统的稳定性。  相似文献