LandScan USA: a high-resolution geospatial and temporal modeling approach for population distribution and dynamics

High-resolution population distribution data are critical for successfully addressing important issues ranging from socio-environmental research to public health to homeland security, since scientific analyses, operational activities, and policy decisions are significantly influenced by the number of impacted people. Dasymetric modeling has been a well-recognized approach for spatial decomposition of census data to increase the spatial resolution of population distribution. However, enhancing the temporal resolution of population distribution poses a greater challenge. In this paper, we discuss the development of LandScan USA, a multi-dimensional dasymetric modeling approach, which has allowed the creation of a very high-resolution population distribution data both over space and time. At a spatial resolution of 3 arc seconds (～90 m), the initial LandScan USA database contains both a nighttime residential as well as a baseline daytime population distribution that incorporates movement of workers and students. Challenging research issues of disparate and misaligned spatial data and modeling to develop a database at a national scale, as well as model verification and validation approaches are illustrated and discussed. Initial analyses indicate a high degree of locational accuracy for LandScan USA distribution model and data. High-resolution population data such as LandScan USA, which describes both distribution and dynamics of human population, clearly has the potential to profoundly impact multiple domain applications of national and global priority.     

遥感与GIS技术支持下的机场选址与工程地质分析

研究将“3S”技术（RS、GIS、GPS）应用到机场地址勘察中,主要是采用现代化遥感技术,以最新遥感图像LANDSATETM（最高空间分辨率15m）,SPOT图像（2．5m）和QUICKBIRD图像（0．61m）等作为信息源,通过遥感图像数据融合、数字镶嵌和影像增强等数字处理,制作不同类型、不同波段和不同分辨率的正射遥感影像及正射影像地图,为机场工程地质勘察提供最佳图像资料。通过遥感图像增强处理、信息提取及GIS空间分析等,对研究区的地质构造,地质灾害等进行解译。并借助GPS进行野外现场调研,查明研究区地质构造的特征,尤其是隐伏断裂、活动性断裂的分布,以及岩溶漏斗、洼地等水文地质现象,为小哨机场工程地质勘察工作提供了基础资料。     

Exploring the structure of the U.S. intercity passenger air transportation network: a weighted complex network approach

The U.S. airline network is one of the most advanced transportation infrastructures in the world. It is a complex geospatial structure that sustains a variety of dynamics including commercial, public, and military operations and services. We study the U.S. domestic intercity passenger air transportation network using a weighted complex network methodology, in which vertices represent cities and edges represent intercity airline connections weighted by average daily passenger traffic, non-stop distance, and average one-way fares. We find that U.S. intercity passenger air transportation network is a small-world network accompanied by dissortative mixing patterns and rich-club phenomenon, implying that large degree cities (or hub cities) tend to form high traffic volume interconnections among each other and large degree cities tend to link to a large number of small degree cities. The interhub air connections tend to form interconnected triplets with high traffic volumes, long non-stop distances, and low average one-way fares. The structure of the U.S. airline network reflects the dynamic integration of pre-existing urban and national transportation infrastructure with the competitive business strategies of commercial airlines. In this paper we apply an emerging methodology to representing, analyzing, and modeling the complex interactions associated with the physical and human elements of the important U.S. national air transport and services infrastructure.     

A digitized global flood inventory (1998–2008): compilation and preliminary results

Floods have profound impacts on populations worldwide in terms of both loss of life and property. A global inventory of floods is an important tool for quantifying the spatial and temporal distribution of floods and for evaluating global flood prediction models. Several global hazard inventories currently exist; however, their utility for spatiotemporal analysis of global floods is limited. The existing flood catalogs either fail to record the geospatial area over which the flood impacted or restrict the types of flood events included in the database according to a set of criteria, limiting the scope of the inventory. To improve upon existing databases, and make it more comprehensive, we have compiled a digitized Global Flood Inventory (GFI) for the period 1998–2008 which also geo-references each flood event by latitude and longitude. This technical report presents the methodology used to compile the GFI and preliminary findings on the spatial and temporal distributions of the flooding events that are contained in the inventory.     

High-resolution monitoring of complex coastal morphology changes: cross-efficiency of SfM and TLS-based survey (Vaches-Noires cliffs,Normandy, France)

High-resolution digital elevation models (HRDEMs) on coastal areas, particularly cliffs, are an important asset for analyzing and quantifying the processes affecting their morphology. The Vaches-Noires coastal cliffs, located at the north-western part of the Pays-d’Auge region (Normandy, France), are an ideal site for the study of subaerial and marine erosion processes. Indeed, the coastline evolves through the accumulation of deposits resulting from rotational landslides and/or mudflows at the base of the cliff which are then undermined by the sea. The 3D modeling of a representative sector of the cliffs appears a suitable solution to monitor and quantify this evolution using HRDEMs. This paper presents the whole of a monitoring protocol, with high spatial resolution and high temporal resolution, on an original location characterized by reliefs of Badlands in coastal environments. The first results of these investigations are described with an evaluation of two methods for the creation of 3D models: a “heavy” method by Terrestrial Laser Scanning (TLS) monitoring, and a “light” method using “Structure from Motion” (SfM) terrestrial photogrammetry. The small investment of time in the field and money is an important asset of the SfM method. The textured rendering quality of the SfM model makes it a powerful tool for geomorphological analysis. According to a recurrent monitoring protocol involving both measurements, it was possible to compare the accuracy of the SfM and TLS models. The results show a high accuracy of the SfM models with an overall average error of 0.05 m. The representations of the zones of accumulation and erosion as well as their spatial succession allow to investigate the dynamics of the involved processes with both methods. Preliminary volume calculation results are conclusive for TLS models.     

Fractally Invariant Distributions and an Application in Geochemical Exploration

Fractal modelling has been applied extensively as a means of characterizing the spatial distribution of geological phenomena that display self-similarity at differing scales of measurement. A fractal distribution exists where the number of objects exhibiting values larger than a specified magnitude displays a power-law dependence on that magnitude, and where this relationship is scale-invariant. This paper shows that a number of distributions, including power-function, Pareto, log-normal and Zipf, display fractal properties under certain conditions and that this may be used as the mathematical basis for developing fractal models for data exhibiting such distributions. Population limits, derived from fractal modelling using a summation method, are compared with those derived from more conventional probability plot modelling of stream sediment geochemical data from north-eastern New South Wales. Despite some degree of subjectivity in determining the number of populations to use in the models, both the fractal and probability plot modelling have assisted in isolating anomalous observations in the geochemical data related to the occurrence of mineralisation or lithological differences between sub-catchments. Thresholds for the main background populations determined by the fractal model are similar to those established using probability plot modelling, however the summation method displays less capacity to separate out anomalous populations, especially where such populations display extensive overlap. This suggests, in the geochemical data example provided, that subtle differences in the population parameters may not significantly alter the fractal dimension.     

The Heat Airspace Cloud Map in Terminal Airspace of Airports Based on Air Passenger Flow and a Case Study in Beijing International Airport

The calculation of air passenger flow density and the recognition of heat airspace in terminal areas of large hub airports is a new challenging research in the intelligent era, that is, using big data can automatically generate air passenger flow and basic rules. Aimed for the air passenger flow density in airport and its relationship between occupation and airspace, based on the establishment of the Beijing International Airport 1 h flight, which consists of basic parameters-latitude, longitude and height, additional parameters-dogleg and speed of trajectories, time parameters, a spatio-temporal data set by clustering trajectories and calculation of aircraft trajectories points was made up. Then, heat cloud map of flight trajectories under 4D conditions was generated. Cell was used to identify the basic parameters and time parameter of heat airspace; grid graphs of flight trajectories were used to identify additional parameters and explain the influence on heat airspace; probability fitting graphs were used to verify the accuracy of 4D results. The conclusion is as follows: there are two areas of Beijing International Airport, which have the high density and at two different heights there also exist hot peaks; flight trajectories and speed of trajectories also affect the heat airspace. The variation of heat airspace caused by different flight occupancy time in 4D recognition was revealed. The method realized the 4D heat cloud map of flight trajectories, which is better for detailed and accurate information construction, expression of spatial changes, and more the parameters of density and visualization of temporal and spatial range, which can assist the automatic dynamic airspace sectorization and decision making on airspace allocation, and also have a definite reference meaning in alleviating the contradiction between the current air traffic demand and limited airspace.     

Assessing the use of global land cover data for guiding large area population distribution modelling

Gridded population distribution data are finding increasing use in a wide range of fields, including resource allocation, disease burden estimation and climate change impact assessment. Land cover information can be used in combination with detailed settlement extents to redistribute aggregated census counts to improve the accuracy of national-scale gridded population data. In East Africa, such analyses have been done using regional land cover data, thus restricting application of the approach to this region. If gridded population data are to be improved across Africa, an alternative, consistent and comparable source of land cover data is required. Here these analyses were repeated for Kenya using four continent-wide land cover datasets combined with detailed settlement extents and accuracies were assessed against detailed census data. The aim was to identify the large area land cover dataset that, combined with detailed settlement extents, produce the most accurate population distribution data. The effectiveness of the population distribution modelling procedures in the absence of high resolution census data was evaluated, as was the extrapolation ability of population densities between different regions. Results showed that the use of the GlobCover dataset refined with detailed settlement extents provided significantly more accurate gridded population data compared to the use of refined AVHRR-derived, MODIS-derived and GLC2000 land cover datasets. This study supports the hypothesis that land cover information is important for improving population distribution model accuracies, particularly in countries where only coarse resolution census data are available. Obtaining high resolution census data must however remain the priority. With its higher spatial resolution and its more recent data acquisition, the GlobCover dataset was found as the most valuable resource to use in combination with detailed settlement extents for the production of gridded population datasets across large areas.     

热质输运-反应体系的石英溶解与沉淀的模拟研究

介质中热质输运-反应体系对于热质成矿、污物迁移等十分重要。这里利用热质流体输运动力学模型与石英溶解与沉淀的化学动力学模型,以及多孔介质的本构关系,建立了一个热质输运、反应动力学藕合模型。并使用此模型研究了局部的温度变化和颗粒半径不均一分布对研究区域内温度场和浓度场的变化情况,其结论是它们之间的耦合可能打破系统的平衡,驱使系统长时间持续进行流体输运-反应动力学过程。     

秦沈客运专线软弱地基沉降控制措施与研究技术

要保证客运专线和高速铁路正常运行 ,路基沉降必须得到有效控制。本文结合秦沈客运专线软弱地基段土质特性 ,提出了地基沉降控制的加固措施、计算方法和试验研究方案 ,对进一步开展这项工作有一定指导意义     

Reservoirs as sentinels of catchments: the Rappbode Reservoir Observatory (Harz Mountains, Germany)

Reservoirs can be viewed as sentinels of their catchments and a detailed monitoring of reservoir systems informs about biogeochemical and hydrological processes at the catchment scale. We developed a comprehensive online monitoring system at Rappbode reservoir, the largest drinking water reservoir in Germany, and its inflows. The Rappbode Reservoir Observatory comprises of a set of online-sensors for the measurement of physical, chemical, and biological variables and is complemented by a biweekly limnological sampling schedule. Measurement stations are deployed at the four major inflows into the system, at the outlets of all pre-reservoirs, as well as in the main reservoir. The newly installed monitoring system serves both scientific monitoring and process studies, as well as reservoir management. Particular emphasis is paid to the monitoring of short-term dynamics and many variables are measured at high temporal resolution. As an example, we quantitatively documented a flood event which mobilised high loads of dissolved organic carbon and changed the characteristics of the receiving reservoir from eutrophic to dystrophic within a few days. This event could have been completely missed by conventional biweekly sampling programs, but is relevant for biogeochemical fluxes at the catchment scale. We also show that the high frequency data provide a deeper insight into ecosystem dynamics and lake metabolism. The Rappbode Reservoir Observatory; moreover, offers a unique study site to apply, validate, and develop state of the art lake models to improve their predictive capabilities.     

Fish population responses to chronic and acute pollution: The influence of life history strategies

We have developed a simulation model to estimate pollution effects on economically important estuarine-dependent fish populations. Traditionally, pollution studies have focused upon impacts on individual organisms; however, wise management of marine resources depends upon an understanding of dynamics at the population level. As a required first step toward conducting relevant pollution studies, we have compiled available life history data on eight species (14 spatial-temporal stocks), concentrating on age-specific rates of growth, survival, and fecundity. Leslie matrix models of species population dynamics were used to predict pollutant impacts—mediate through changes in 1st-year survival. On average, and without compensation, these modelled stocks respond to a one-time-50% reduction in first-year survival by taking ten years to equilibrate at 88% of their preimpact abundance. Our synthesis of the data included a search for derived (standardized) population parameters to evaluate differences in susceptibility among and within fish populations to pollutant stresses. We demonstrated that knowledge of a species’ age-specific fecundity pattern provides additional predictive power of its response to pollution perturbation.     

Vulnerability of population and transportation infrastructure at the east bank of Delaware Bay due to coastal flooding in sea-level rise conditions

Catastrophic flooding associated with sea-level rise and change of hurricane patterns has put the northeastern coastal regions of the United States at a greater risk. In this paper, we predict coastal flooding at the east bank of Delaware Bay and analyze the resulting impact on residents and transportation infrastructure. The three-dimensional coastal ocean model FVCOM coupled with a two-dimensional shallow water model is used to simulate hydrodynamic flooding from coastal ocean water with fine-resolution meshes, and a topography-based hydrologic method is applied to estimate inland flooding due to precipitation. The entire flooded areas with a range of storm intensity (i.e., no storm, 10-, and 50-year storm) and sea-level rise (i.e., current, 10-, and 50-year sea level) are thus determined. The populations in the study region in 10 and 50 years are predicted using an economic-demographic model. With the aid of ArcGIS, detailed analysis of affected population and transportation systems including highway networks, railroads, and bridges is presented for all of the flood scenarios. It is concluded that sea-level rise will lead to a substantial increase in vulnerability of residents and transportation infrastructure to storm floods, and such a flood tends to affect more population in Cape May County but more transportation facilities in Cumberland County, New Jersey.     

Development of an urban landslide cellular automata model: a case study of North Vancouver, Canada

Many GIS-based landslide models require detailed datasets that are ideally collected from field measurements, which can incur high costs for carrying out surveys. Even when the data is on hand, implementing physics-based slope stability techniques can be difficult. Common research practice uses differential equations to characterize the dynamic flow of a landslide, but it is often laborious without making substantial simplifications. A possible solution is to implement a cellular automata modeling approach, which represents both spatial and temporal components, to simulate the dynamics of the landslide propagation process. In this study, a simplified cellular automata model is developed for the effective prediction of landslide runouts, where the data requirement is a high resolution digital elevation model (DEM). Parameters, such as slope and slope curvature features, are derived from the DEM and coupled with logistic regression. The developed model is implemented on the Patrick and Dawson-Chu Slide in North Vancouver, Canada. The results from this study site were favorable, given almost 90% agreement between simulated landslides and data obtained for real landslides. In addition, sensitivity analysis was performed on the initiation sites to test the model logic and outputs of the landslide flow.     

Design and Long-Term Monitoring of Tokyo International Airport Extension Project Constructed on Super-Soft Ground

To meet the increasing demand for air transportation, Ministry of Land, Infrastructure and Transport had carried out the offshore extension project at Tokyo International Airport (Haneda Airport). The airport should be constructed to be perfectly level, but the ground conditions with very thick layers of super soft dredged soils and need for reclamation made the task very difficult. Because of large amount of consolidation settlement, ground improvement by combined vertical drain method was applied to decrease residual and differential settlement after opening of new airport. This paper is aimed to introduce the design concept and method of ground improvement for this project. In addition the result of ground improvement is keeping satisfactory performance for operating airport confirmed by long-term monitoring for airport facilities.     

Alpine timberline population dynamics under climate change: a comparison between Qilian juniper and Qinghai spruce tree species in the middle Qilian Mountains of northeast Tibetan Plateau

Alpine forest population dynamics are sensitive to climate change. Response patterns are complex, and it is still unclear as to whether or not population dynamics are species‐dependent. In this study, population dynamic patterns for alpine timberline Qilian juniper and Qinghai spruce tree species in the mid Qilian Mountains were determined from approximately 1500 C.E. by applying dendrochronological methods. The results showed that these tree species have different forest population dynamics. The Qinghai spruce recruitment rate was clearly higher than that of Qilian juniper. Furthermore, the temporal population dynamic patterns of Qinghai spruce samples taken at different sites were consistent whereas those of the Qilian juniper samples were not. Qinghai spruce population dynamics were primarily affected by temperature, with positive correlations between temperature and recruitment. By contrast, with the exception of a positive to negative shift in the relationship between temperature and Qilian juniper population dynamics, Qilian juniper recruitment significantly decreased when its density reached a relatively high level. Moreover, a shift in the temperature‐recruitment relationship and a decrease in recruitment occurred simultaneously, indicating that Qilian juniper population dynamics were affected by both temperature and density. Species to species differences were also observed when compared with previous studies within the mid Qilian Mountains, confirming the existence of species‐dependent population dynamic patterns. Forest recruitment dynamic patterns and tree recruitment‐climate relationships may help to provide clues for future studies on forest management, conservation and utilization.     

Social vulnerability assessment of natural hazards on county-scale using high spatial resolution satellite imagery: a case study in the Luogang district of Guangzhou,South China

Social vulnerability assessment of natural hazards aims to identify vulnerable populations and provide decision makers with scientific basis for their disaster prevention and mitigation decisions. A new method based on remote sensing is presented here to establish a model of social vulnerability for county-scale regions that lack of relative data. To calculate population density, which is the most important indicator in social vulnerability assessment, first, a statistical model is established to estimate the population on village level. Then a new concept defined as “population density based on land use” is created to replace the arithmetic population density. The former has taken the dynamic human distribution related to land use into account; thus, it can map the population distribution more realistically. The other two indicators are age structure and distance to hospital. The application of this method to the Luogang District of Guangzhou, South China demonstrated its capability of providing high spatial resolution and reasonable social vulnerability for social vulnerability assessment of natural hazards.     

环境模拟和GIS集成的初步研究

GIS与环境模拟在技术、研究内容、方法上的进一步集成,具有广泛的应用前景.以开展的流域土壤和水资源研究模型的集成和系统化及其应用项目的实际工作,说明了环境模拟和GIS技术集成的必然性;从GIS技术的发展,环境模拟模型的改进与完善,数据的初始化与管理等方面系统地论述了环境模拟模型和GIS集成的必要性.通过现有集成模式的分析,对二者集成的概念框架以及不同的集成方式进行了概念性的描述,结合研究项目给出了集成示例.     

扩散年代学：进展与展望

地质年代学为地球与行星科学研究提供时间坐标,以定量解析地质过程先后关系和时间尺度。历经百余年发展,定年技术在研究对象、测试效率、空间分辨率和时间分辨率等维度均得到大幅度提高,地质年代学研究已从仅提供时代约束过渡到更加强调对地质过程时间尺度与节律的研究,进而约束地质事件的驱动机制和互馈机理。然而,基于放射性同位素衰变的绝对定年技术精度存在物理极限,不能无限提高,且其时间分辨率一般随年龄增加而变差,难以满足深时地质研究的高时间分辨率需求,发展时间分辨率不受绝对年龄约束的相对定年技术是地质年代学的重要发展方向。本文围绕扩散年代学这一具有重要发展前景的相对定年技术,在系统回顾其理论模型和测量技术的基础上,重点对制约扩散年代学准确性和精确性的问题,如扩散系数的不确定性、扩散初始条件假设、浓度曲线的测试质量以及误差评估等进行了探讨。本文还对扩散年代学近年来在岩浆储存与运移、成矿时间尺度与节律和变质过程等领域取得的部分重要进展予以评述。精确的扩散系数是开展扩散年代学研究的前提,以石英中的Ti为例,不同实验给出的扩散系数差异超过3个数量级,据此计算的花岗岩岩浆在固相线上的储存时间从几十年变化到百万年尺度,显著影响我们对岩浆储存状态的理解。高质量的元素浓度剖面测量是扩散年代学的关键,因石英Ti含量的高空间分辨率精准测量较为困难,CL灰度常被作为Ti含量的替代指标,但这需要考虑Al等元素对CL灰度的影响,并严格评估Ti含量校正曲线和扩散剖面空间尺度不匹配对定年结果的影响。高温变质过程U Pb定年通常给出较为离散的表观年龄,并被解释为变质过程具有较长的持续时间,这一定程度上可以通过高温下同位素体系因扩散引起的不封闭予以解释。展望未来,进一步完善扩散年代学在高温体系中的研究,拓展在中低温条件下的应用,并与绝对定年深度结合,是扩散年代学的重要发展方向,也是实现深时地质研究高时间分辨率解析的必由之路。     

西昆仑成矿带高分辨率遥感调查主要进展与成果

遥感技术是地质矿产调查工作不可或缺的手段之一。以高空间分辨率(WorldView -2、QuickBird、IKO-NOS)和中等空间分辨率(ASTER、ETM+)卫星数据为遥感数据源,利用多元、多层次遥感技术,完成了西昆仑成矿带高分辨率遥感地质调查工作。制作了调查区1∶5万正射影像图,为遥感地质调查工作提供了既具有精确地理坐标,又能直观反映区域交通和地质灾害分布状况等信息的基础影像地图;通过遥感地质解译和遥感蚀变异常信息提取,结合野外验证,基本查明了调查区区域(含矿/成矿)地质体、(含矿/成矿)地质构造的展布特征和遥感矿化蚀变异常信息的分布情况;在典型矿床找矿模型、区域成矿分区、区域成矿/控矿要素分布特征等研究工作的基础上,开展了遥感找矿预测,并对部分遥感找矿预测区进行了野外验证和简易工程查证。本次调查共为调查区推荐3349处遥感蚀变异常区,圈定146个找矿预测区,推荐16个区调/矿调工作优先部署区和30个一般部署区,充分发挥了遥感技术在区域矿产地质调查工作中的先行作用。