Research Note—A New Method for Mapping Population and Understanding the Spatial Dynamics of Disease in Urban Areas: Asthma in the Bronx,New York

Determining an accurate depiction of population distribution for urban areas in order to develop an improved "denominator" is important for the calculation of higher-precision rates in GIS analyses, particularly when exploring the spatial dynamics of disease. Rather than using data aggregated by arbitrary administrative boundaries such as census tracts, we developed the Cadastral-Based Expert Dasymetric System (CEDS), an interpolation method using ancillary information to delineate areas of homogeneous values. This method uses cadastral data, land-use filters, modeling by expert system routines, and validation against various census enumeration units and other data. The CEDS method is presented through a case study of asthma hospitalizations in the borough of the Bronx in New York City, in relation to proximity buffers constructed around major sources of air pollution. The analysis using CEDS shows that asthma hospitalization risk due to proximity to pollution sources is greater than previously calculated using traditional disaggregation methods.     

Identifying and assessing the residency effect in Pocatello,Idaho, using combined census and parcel data

Human residency is the spatial effect source on ecosystem and thus it should be studied and assessed. Supporting residency effect research, this study developed and applied procedures and a model to combine census and parcel data for the assessment. The case study is in Pocatello, Idaho, where revealing land service associated with flood control and locating/evaluating resident effect are needed. Methods include (1) data mining, (2) land service valuation, (3) data screening, (4) integration of census and parcel data, (5) data screening, and (5) analysis and modeling with R programing language and ArcMap. Results are, for land service assessment, land value per area unit in residence areas (LAND) along the concrete channel (for flood control) was less than that along the Portneuf River. Spatial responses under LAND to a source effect (either the concrete channel or the river) are the same. The applied methods helped locate and assess a variety of residency effects spatio-temporally. Results informed the human preferences under LAND and the effect distribution to support decision-making. Technically, using the parcels as a baseline provided comprehensive results with a fine resolution for the effect study, particularly as combined with the census data. This study suggests using a data screening and validation procedure besides the mining approach to minimize outcome uncertainty.     

Mapping fine-scale population distributions at the building level by integrating multisource geospatial big data

Fine-scale population distribution data at the building level play an essential role in numerous fields, for example urban planning and disaster prevention. The rapid technological development of remote sensing (RS) and geographical information system (GIS) in recent decades has benefited numerous population distribution mapping studies. However, most of these studies focused on global population and environmental changes; few considered fine-scale population mapping at the local scale, largely because of a lack of reliable data and models. As geospatial big data booms, Internet-collected volunteered geographic information (VGI) can now be used to solve this problem. This article establishes a novel framework to map urban population distributions at the building scale by integrating multisource geospatial big data, which is essential for the fine-scale mapping of population distributions. First, Baidu points-of-interest (POIs) and real-time Tencent user densities (RTUD) are analyzed by using a random forest algorithm to down-scale the street-level population distribution to the grid level. Then, we design an effective iterative building-population gravity model to map population distributions at the building level. Meanwhile, we introduce a densely inhabited index (DII), generated by the proposed gravity model, which can be used to estimate the degree of residential crowding. According to a comparison with official community-level census data and the results of previous population mapping methods, our method exhibits the best accuracy (Pearson R = .8615, RMSE = 663.3250, p < .0001). The produced fine-scale population map can offer a more thorough understanding of inner city population distributions, which can thus help policy makers optimize the allocation of resources.     

中华人民共和国行政区划单元数据库的建立和应用

中华人民共和国行政区划单元数据库是将全国2300个以上的县和县以上的行政区划的编码和分布位置进行存储、管理并提供应用它的一组程序。本文对数据库的建立方法和应用作简要介绍。     

The regional types of China’s floating population: Identification methods and spatial patterns

With the rapid increase of the number and influence of floating population in China, it is urgently needed to understand the regional types of China’s floating population and their spatial characteristics. After reviewing the current methods for identifying regional types of floating population, this paper puts forward a new composite-index identification method and its modification version which is consisted of two indexes of the net migration rate and gross migration rate. Then, the traditional single-index and the new composite-index identification methods are empirically tested to explore their spatial patterns and characteristics by using China’s 2000 census data at county level. The results show: (1) The composite-index identification method is much better than traditional single-index method because it can measure the migration direction and scale of floating simultaneously, and in particular it can identify the unique regional types of floating population with large scale of immigration and emigration. (2) The modified composite-index identification method, by using the share of a region’s certain type of floating population to the total in China as weights, can effectively correct the over- or under-estimated errors due to the rather large or small total population of a region. (3) The spatial patterns of different regional types of China’s floating population are closely related to the regional differentiation of their natural environment, population density and socio- economic development level. The three active regional types of floating population are mainly located in the eastern part of China with lower elevation, more than 800 mm precipitation, rather higher population densities and economic development levels.     

Estimating ethnic change in London, 1981-91, using a variety of census data

"This paper provides estimates of ethnic minority populations in 1981 in Greater London so that spatial population change can be measured. The estimation method involves the application of conditional probabilities of ethnicity given the country of birth. Several different data sources from the census of population have been used to compute the conditional probabilities. Each of these sources has deficiencies; the new method proposed here employs data on 1981-91 survivors in the ONS Longitudinal Study (LS). The estimated ethnic minority populations for 1981 are smaller than those generated using 1991 Census data, and hence the estimate of change is larger. Careful pairwise comparisons are made between alternative estimates. A set of very different maps of change, based on the LS method, are presented and interpreted for the ethnic groups of London at the borough scale."     

The change in population density from 2000 to 2010 and its influencing factors in China at the county scale

Studying the change in population distribution and density can provide important basis for regional development and planning. The spatial patterns and driving factors of the change in population density in China were not clear yet. Therefore, using the population census data in 2000 and 2010, this study firstly analyzed the change of population density in China and divided the change in all 2353 counties into 4 types, consisting of rapid increase, slow increase, slow decrease and rapid decrease. Subsequently, based on the partial least square (PLS) regression method, we recognized the significant factors (among 11 natural and social-economic factors) impacting population density change for the whole country and counties with different types of population change. The results showed that: (1) compared to the population density in 2000, in 2010, the population density in most of the counties (over 60%) increased by 21 persons per km² on average, while the population density in other counties decreased by 13 persons per km². Of all the 2353 counties, 860 and 589 counties respectively showed rapid and slow increase in population density, while 458 and 446 counties showed slow and rapid decrease in population density, respectively. (2) Among the 11 factors, social-economic factors impacted population density change more significantly than natural factors. The higher economic development level, better medical condition and stronger communication capability were the main pull factors of population increase. The dense population density was the main push factor of population decrease. These conclusions clarified the spatial pattern of population change and its influencing factors in China over the past 10 years and could provide helpful reference for the future population planning.     

中国流动人口地域类型——划分方法及空间分布(英文)

With the rapid increase of the number and influence of floating population in China,it is urgently needed to understand the regional types of China’s floating population and their spatial characteristics. After reviewing the current methods for identifying regional types of floating population,this paper puts forward a new composite-index identification method and its modification version which is consisted of two indexes of the net migration rate and gross migration rate. Then,the traditional single-index and the new composite-index identification methods are empirically tested to explore their spatial patterns and characteristics by using China’s 2000 census data at county level. The results show:(1) The composite-index identification method is much better than traditional single-index method because it can measure the migration direction and scale of floating simultaneously,and in particular it can identify the unique regional types of floating population with large scale of immigration and emigration. (2) The modified composite-index identification method,by using the share of a region’s certain type of floating population to the total in China as weights,can effectively correct the over-or under-estimated errors due to the rather large or small total population of a region. (3) The spatial patterns of different regional types of China’s floating population are closely related to the regional differentiation of their natural environment,population density and socio-economic development level. The three active regional types of floating population are mainly located in the eastern part of China with lower elevation,more than 800 mm precipitation,rather higher population densities and economic development levels.     

中国暴雨洪涝灾情时空格局及影响因素

暴雨洪涝灾害给中国造成了巨大人口和经济损失.本文通过对中国气象灾情普查数据的分析,结合小时降水数据、统计年鉴等资料,研究了 1984-2007年间中国极端降水和暴雨洪涝灾情时空分异特征.在此基础上,采用地理探测器研究了中国暴雨洪涝灾情时空格局的影响因素.结果表明,研究时段内全国极端降雨指标没有一致的变化趋势.长江、珠江...     

GIS-based flood hazard mapping at different administrative scales: A case study in Gangetic West Bengal, India

This paper addresses the need for an efficient and cost-effective methodology for preparing flood hazard maps in data poor countries, particularly those under a monsoon regime where floods pose a recurrent danger. Taking Gangetic West Bengal, India, as an example and using available historical data from government agencies, the study compiled a regional map indicating hazard prone subregional areas for further detailed investigation, thereby isolating actual high risk localities. Using a GIS (Geographical Information System), a composite hazard index was devised incorporating variables of flood frequency, population density, transportation networks, access to potable water, and availability of high ground and maximum risk zones were mapped accordingly. A digital elevation model derived from high resolution imagery available in the public domain was used to calculate elevated areas suitable for temporary shelter during a flood. Selecting administrative units of analysis at the lowest possible scales – rural development blocks (regional) and revenue villages (subregional) – also ensures that hazard mapping is prepared in line with the existing rural planning and administrative authorities responsible for remedial intervention.     

人口密度空间化的一种方法

人口密度空间化是地理学中一个重要的研究课题,但是传统方法直接生成的人口密度分布图具有不同区域间突变的缺点。该文中基于面积权重内插法与邻域平均法原理,以MapInfo为软件平台,在缺乏地形图、RS图片等资料的情况下,提出人口密度空间化的一种方法——网格单元面积权重内插法,并以丰县为研究区域进行例证。结果表明：该方法有效缓和了传统方法直接生成的人口密度图中的突变线,制作的人口密度Grid专题地图能够很好地反映人口密度的平均性,生成的人口密度三维可视化地图符合人口密度的空间分布特点。     

And Did the Walls Come Tumbling Down? Ethnic Residential Segregation in Four U.S. Metropolitan Areas 1980-2000

The initial releases of data from the 2000 U.S. Census allow exploration of the extent of change, if any, in residential segregation in four major cities, where substantial population growth has continued to generate increased ethnic diversity. Using a recently established method of classifying residential areas according to their ethnic composition which facilitates comparative study over time and space, this paper examines segregation trends in Chicago, Los Angeles, New York, and Miami over the period 1980-2000 in the context of recent discussions of the nature of residential patterns there. It finds that though there has been some reduction in the extent of extreme segregation areas that are predominantly either White or African American with consequent greater ethnic mixing at the census tract level, nevertheless cores of extreme segregation remain, and these are being extended with greater segregation of the Hispanic population. Ethnic residential segregation in United States' metropolitan areas attracted much research throughout the 20th century, with each census providing new impetus for mapping and analysis. The 2000 census will be no exception, providing data with which the extent of change can be assessed after a further decade in which discrimination on the grounds of race and color was illegal. This paper provides an initial exploration for four metropolitan areas that have experienced substantial recent multi-ethnic in-migration. Using a method for classifying residential areas designed to facilitate comparative studies over space and time, it explores the extent of desegregation during the previous 20 years for each of the four main census ethnic groups.     

Space,Place, Population and Census Analysis in Australia

The Australian Census of Population and Housing is a census of people not places. However, where people live and work can be of major relevance in our search for explaining and understanding their behaviour. This paper argues that the place dimension in the Australian census has not been exploited very effectively in this respect. Three dimensions of the issue are addressed. Firstly, the spatial units commonly used for analysis of census data often are not appropriate to the problem being investigated. The spatial units in the Australian Standard Geographical Classification (ASGC) used for census data rarely represent meaningful social, economic and environmental regions. Secondly, the use of a simple urban/rural dichotomy is criticised as being a very blunt instrument to differentiate settlement types. Thirdly, the relationship between people and place in the census is discussed. While for the most part the census relates people to a single location—their place of usual residence—this is only one of the places with which people regularly interact. It is suggested that there is a need to adopt practices in the census which allow a range of population geographies to be defined. In conclusion it is argued that innovation in the Australian census, especially with the introduction of meshblocks and contemporary methodology and technology in Geographical Information Systems, makes it possible to analyse spatially referenced data in ways that can address these three issues.     

A LiDAR-based flood modelling approach for mapping rice cultivation areas in Apalit,Pampanga

Majority of rice cultivation areas in the Philippines are susceptible to excessive flooding owing to intense rainfall events. The study introduces the use of fine scale flood inundation modelling to map cultivation areas in Apalit, a rice-producing municipality located in the province of Pampanga in the Philippines. The study used a LiDAR-based digital elevation model (DEM), river discharge and rainfall data to generate flood inundation maps using LISFLOOD-FP. By applying spatial analysis, rice cultivation zone maps were derived and four cultivation zones are proposed. In areas where both depth and duration exceed threshold values set in this study, varieties tolerant to stagnant flooding and submergence are highly recommended in Zone 1, where flood conditions are least favorable for any existing traditional lowland irrigation varieties. The study emphasizes that a decline in yield is likely as increasing flood extents and longer submergence periods may cause cultivation areas for traditional irrigated lowland varieties to decrease over time. This decrease in yield may be prevented by using varieties most suitable to the flooding conditions as prescribed in the rice zone classification. The method introduced in this study could facilitate appropriate rice cultivation in flood-prone areas.     

Remote sensing of temporal and spatial variations in pool size, suspended sediment, turbidity, and Secchi depth in Tuttle Creek Reservoir, Kansas: 1993

Four dates of Landsat Thematic Mapper data from 1993, April 9, July 30, August 15, and September 16, were used to assess temporal and spatial patterns of lake area and dimensions of suspended sediment concentration in Tuttle Creek Reservoir, Kansas. In 1993, excessive precipitation in the Big Blue River Basin, and throughout much of the Upper Middle West, led to widespread flooding. Rains produced substantial erosion, sediment movement down the stream network, and a runoff volume that filled Tuttle Creek Reservoir, a U.S. Army Corps of Engineers flood control structure. The April 9 data are from before the flood, the July 30 data are from the time of maximum pool size and use of the emergency spillway, and the August and September data document the declining pool sizes. Three separate analyses were performed on each of the four dates of Thematic Mapper data. One set of analyses involved applying an existing physical model that uses at-satellite reflectance for TM Band 3 to estimate variations in suspended sediment, turbidity, and Secchi depth throughout the reservoir. Maps of estimated parameters of water quality for the four individual dates were compared and analyzed to document spatial and temporal changes. The second research method involved unsupervised classification (ERDAS ISODATA algorithm) of the data from the Tuttle Creek Reservoir. Water areas were grouped into coherent classes for further spatial analysis using a two-step or layered classification procedure for each date. The third analysis used a GIS overlay technique to compare the area of the water surface for each of the four dates with the flood pool as marked on U.S.G.S. 7-1/2 minute quadrangles. Comparisons document the major change in lake area between April and July, the high levels of suspended sediment in mid-summer, and the decline in pool size and concentrations of suspended sediment by mid-September. The study illustrates the advantages of using remote sensing to assist in documenting a relatively short-term environmental hazard. This study also demonstrates the value of Landsat Thematic Mapper data for use in mapping geographic variations in water area and quality in conjunction with a major flood event.     

Comparison of flood hazard assessments on desert piedmonts and playas: A case study in Ivanpah Valley, Nevada

Accurate and realistic characterizations of flood hazards on desert piedmonts and playas are increasingly important given the rapid urbanization of arid regions. Flood behavior in arid fluvial systems differs greatly from that of the perennial rivers upon which most conventional flood hazard assessment methods are based. Additionally, hazard assessments may vary widely between studies or even contradict other maps. This study's chief objective was to compare and evaluate landscape interpretation and hazard assessment between types of maps depicting assessments of flood risk in Ivanpah Valley, NV, as a case study. As a secondary goal, we explain likely causes of discrepancy between data sets to ameliorate confusion for map users. Four maps, including three different flood hazard assessments of Ivanpah Valley, NV, were compared: (i) a regulatory map prepared by FEMA, (ii) a soil survey map prepared by NRCS, (iii) a surficial geologic map, and (iv) a flood hazard map derived from the surficial geologic map, both of which were prepared by NBMG. GIS comparisons revealed that only 3.4% (33.9 km²) of Ivanpah Valley was found to lie within a FEMA floodplain, while the geologic flood hazard map indicated that ~ 44% of Ivanpah Valley runs some risk of flooding (Fig. 2D). Due to differences in mapping methodology and scale, NRCS data could not be quantitatively compared, and other comparisons were complicated by differences in flood hazard class criteria and terminology between maps. Owing to its scale and scope of attribute data, the surficial geologic map provides the most useful information on flood hazards for land-use planning. This research has implications for future soil geomorphic mapping and flood risk mitigation on desert piedmonts and playas. The Ivanpah Valley study area also includes the location of a planned new international airport, thus this study has immediate implications for urban development and land-use planning near Las Vegas, NV.     

A GIS Analysis to Evaluate Areas Suitable for Crushed Stone Aggregate Quarries in New England,USA

Aggregate is a low unit-value mineral commodity. Costs to move aggregate from the mine site to the point of use is a large fraction of the resource cost to users. Production sites for aggregate occur where suitable source materials exist and where transportation and market conditions are favorable. The increasing demand for aggregate and the difficulty of developing and permitting new sites and of renewal of permits on existing sites of aggregate production indicates that aggregate will be supplied from sources yet to be developed or delineated in many areas. Site development and permitting for aggregate production is difficult because many land management plans and zoning actions fail to anticipate prospective source areas for aggregate in a way that is consistent with both the source rock quality and the transportation and socioeconomic factors that define the economic viability of the industry. Spatial analysis provides a method to integrate both geology and economic (transportation and marketplace) parameters in a regional model. Weights of evidence (WofE) analysis has been used to measure the spatial correlation of geologic map, transportation network, and population data with current production sites for crushed stone aggregate in the New England region of the northeastern United States. Weighted logistic regression (WLR) is used with the WofE results to rank areas in terms of their relative suitability for production of crushed stone. Spatial analysis indicates that 85% of the 106 crushed stone aggregate quarries in New England are sited within 1.6 km (1 mile) of either a principal highway or rail line in the region. Seventy-eight percent of crushed stone aggregate quarries are sited in census tracts with population densities exceeding 100 people/mile². These relations illustrate the importance of proximity to both transportation corridors and developing areas where aggregate is predominately used. Only one active crushed stone quarry is located in a census tract with a population density less than 15 people/mile², reflecting the lack of sufficient market demand in many rural areas to develop an operation there. However, since 1990, almost all new quarries have been developed in census tracts with population densities less than 200 people/mile², indicating the difficulty of permitting new quarry sites in highly populated areas. Crushed stone aggregate is produced predominately from three hard rock types that are distributed widely in New England; 28% of sites use granitic rock, 25% use carbonate rocks, and 25% use mafic rock types that are categorized as trap rock by the aggregate industry. The other crushed stone aggregate sources include a variety of fine-grained metamorphic rock types. Carbonate rocks and Jurassic basalt (the primary trap rock source) are the most prevalent source rocks on an area-weighted basis. Spatial analysis can be used on a regional scale to rank areas by their relative suitabilityfor crushed stone aggregate production based on geology, transportation, and population parameters. The results of this regional analysis can identify areas for more detailed evaluation. As transportation or population features change, the model can be revised easily to reflect these changes.     

A population density grid for Spain

This article describes a high-resolution land cover data set for Spain and its application to dasymetric population mapping (at census tract level). Eventually, this vector layer is transformed into a grid format. The work parallels the effort of the Joint Research Centre (JRC) of the European Commission, in collaboration with Eurostat and the European Environment Agency (EEA), in building a population density grid for the whole of Europe, combining CORINE Land Cover with population data per commune. We solve many of the problems due to the low resolution of CORINE Land Cover, which are especially visible with Spanish data. An accuracy assessment is carried out from a simple aggregation of georeferenced point population data for the region of Madrid. The bottom-up grid constructed in this way is compared to our top-down grid. We show a great improvement over what has been reported from commune data and CORINE Land Cover, but the improvements seem to come entirely from the higher resolution data sets and not from the statistical modeling in the downscaling exercise. This highlights the importance of providing the research community with more detailed land cover data sets, as well as more detailed population data. The dasymetric grid is available free of charge from the authors upon request.     

Reconstructing the extraordinary palaeoflood events during 3200-2800 a BP in the upper reaches of Hanjiang River Valley,China

Palaeoflood hydrology study is a leading subject in global change study. Through field investigation in the upper reaches of Hanjiang River, palaeoflood slackwater deposits (SWD) were found in the bedrock gorges of the Yunxi reach. The results of field observation, laboratory analysis including particle-size distribution and magnetic susceptibility, and comparison with modern flood deposits, the SWD were identified as the most typical Holocene palaeoflood deposits of the Hanjiang River. By using stratigraphic correlation and OSL dating method, the palaeoflood event was dated to be 3200-2800 a BP at the turn from the middle to late Holocene. According to the palaeoflood peak stage and hydraulic parameters, the peak discharges of the palaeoflood were reconstructed as 48,830-51,710 m3/s by using the slope-area method. At same time, the flood peak discharges of 1983, 2005 and 2010 severe floods were reconstructed with the same method and hydraulic parameters in the same cross section. The error between the reconstructed and gauged discharges was 1.99%-4.21%. This showed that the reconstructed palaeoflood peak discharges were reliable. The flood peak discharge-frequency relationship at 10,000-year time scale was established by a combination of the gauged flood, historical flood and palaeoflood hydrological data. These results are very important for hydraulic engineering and flood mitigation on the Hanjiang River.     

基于地理大数据和多源信息融合的区域未来人口精细化空间分布模拟研究——以珠江三角洲为例

首先采用队列因素法和CA-Markov模型对区域未来人口规模和土地利用格局进行模拟预测,并结合POI地理大数据,利用多源信息融合法构建区域未来人口精细化空间分布模拟模型,以珠江三角洲城市群2030年各区县精细化的人口空间分布预测进行实证分析。结果表明：① 采用队列因素法进行珠江三角洲各区县人口规模预测的相对误差大部分在5%以下,基于CA-Markov模型土地利用模拟的Kappa系数达到0.97;② 珠江三角洲城市群精细化的人口空间分布模拟数据与实际人口数据的拟合趋势线R²达到了0.90,模拟效果优于Worldpop数据集,体现了POI地理大数据与多源信息融合在精细化人口空间分布模拟上的优势;③ 珠江三角洲未来人口呈现由中心向外围扩散和递减的空间分布格局,空间差异显著且较为稳定,70%的人口集中在广州、深圳、东莞和佛山等核心城市。