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1.
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.  相似文献   

2.
Database of geo-hydrological disasters for civil protection purposes   总被引：6，自引：2，他引：4  
This paper presents the results of a research concerning available historical information about natural hazards (landslides and floods) and consequent disasters in the Consortium of Mountain Municipalities of Valtellina di Tirano, in Northern Italy. A geo-referenced database, collecting information till 2008, was designed with the aim of using available data of historical events for hazard estimation and the definition of risk scenarios as a basis for Civil Protection planning and emergency management purposes. This database and related statistics about landslides and floods are shown, and a brief overview of historical disasters caused by natural hazards in the study area is presented. A case study showing how useful the database can be to define a simple but realistic scenario is described. Information availability and reliability is discussed and possible uncertainties are underlined. The study shows that collecting and making use of historical information for the definition of hypothetical scenarios and the evaluation of territorial threats is a fundamental source of knowledge to deal with future emergencies.  相似文献   

3.
Adeniyi  P. O. 《GeoJournal》1981,5(3):209-223
Basic to the study of urban growth is information on population and land use changes. These basic data are generally lacking in Nigeria. This paper examines and assesses the growth of urban land use of Lagos (the Federal Capital of Nigeria) through a systematic utilization of sequential serial photographs (taken in 1962 at a scale of 1:40,000, and in 1974, at a scale of 1:20,000) and computer techniques. The land use data resulting are then used in evaluating the population growth of Lagos. The resulting population estimate is then compared with the available population data. The study concludes by recommending the use of remote sensing, especially aerial photography for the acquisition of basic urban data not only in Nigeria but also in other developing countries lacking in such data.  相似文献   

4.
Proper management of solid wastes is a key to environmental sanitation. In recent times the quality of life in most of the cities of the developing world is being deminished by uncontrolled and poorly managed solid wastes in the urban environment. Lagos urban is a typical example. It must be acknowledged that although wastes from homes, businesses and institutions make up a small part of the total load of solid wastes generated in any urban environment they are certainly the most offensive and most dangerous to health when they accumulate near residential points. The quality of life in urban Lagos, Nigeria, with respect to indiscriminate dumping of uncollected solid wastes approximates an aesthetic disaster. This study is therefore designed to examine the problems of solid wastes disposal in Lagos, Nigeria and to provide data base against which effective solid wastes disposal system in the Nigerian capital city might be monitored and tested.Acknowledgement: I wish to thank members of the Environmental Problems and Effects class (1978/9 Session) Geography Department, University of Calabar for their assistance in collecting data for this study.The Year of the last valid population census in Nigeria.  相似文献   

5.
Bohra DM 《GeoJournal》1992,28(4):417-426
Lesotho may be taken as a classic case of how African countries have attempted to cope with the demands of census operations. This paper discusses in respect of Lesotho the existing cartographic base for census mapping; census organization; methodology of census taking in Lesotho; geographical planning and specific strategies evolved in census mapping for the recent 1986 population census; some of the basic problems encountered in enumeration area mapping during the 1986 census; and also the use of census enumeration areas as a frame for national household survey capability programme and post-census cartographic activities.  相似文献   

6.
In the period between 1965 and 1976, when German geographers carried out their fieldwork for the Afrika-Kartenwerk under the sponsorship of the German Research Society, remarkable progress in urban development especially in Lagos could be observed. The cooperation with the Federal Survey Department of Nigeria gave the opportunity for collecting several series of aerial photographs which bring into focus some stages of the overwhelming urban expansion.The materials presented here have been selected to demonstrate some regional structures of the Nigerian capital. — In the geography of today the scientific evaluation of aerial photographs together with findings from local observation and historical as well as statistical data is still undervalued. Through this technique, the more classical and conservative method of geographical analysis, relying on subjective judgement, may regain some of its importance, which it once had in the age of exploration of new territories.Where data is scarce and written records of urban expansion are not available or difficult to extract, aerial photographs can give an impression of certain stages of urban growth. A functional analysis under geographical aspects has to be regarded by changes within spatial units in order to the factors of influence. Those factors are numerous, their influence will cause changes in a series of pushes arising from economic developments of the vast hinterland as well as from social conditions of certain groups of the population. In a metropolitan center, as Lagos, the highest ranking central place of Africa's most populous nation, heterogenous events and a confusing number of planning decisions must be taken into consideration. One consequence of nationwide regional interactions with the metropolis is migratory population dynamics. In pursuing lines of interaction, which originate from economic power, population density, and natural resources, one can hardly isolate a single element of influence because all factors are closely interrelated. For Lagos, there is only limited data available on the social and economic standard of the population, valid basic demographic figures of some value are not available.One still has to accept very rough estimates on population figures, number of industrial workers, the standards of housing and the social and economic hierarchy of the population. The present retrospective analysis of aerial photographs gives an interpretation of the regional structure of the town and indicate possible future development.  相似文献   

7.
The demands and needs of our presently increasing population require that the social decisions for land use must be based on the best and most reliable information that the decision-makers can obtain. Growing mass of natural resource information should be presented in a concise and practical form which the planners and public administrators can readily use without a need to learn about natural resources in detail. One of the means to present this information is a resource evaluation system which consists of four levels of maps: basic resource maps, single-factor maps, limiting-factor maps and final land suitability maps. The basic process used in the system is developing a series of individual maps showing specific kinds of information and superimposing them to identify a degree of suitability for a specific land use. The authors provide an overview of the use of land suitability maps in land use planning in the United States; show what natural resource data planners can require and put to use; outline the way in which earth scientists can evaluate and present the data needed; and finally demonstrate the land suitability analysis by case studies. Also briefly discussed is the need for information other than earth-science data. Land use planning and decision-making process is an intricate mixture of scientific, engineering, ecological, sociological, economic, cultural and political factors and forces. Obvious as it may seem this fact is nevertheless often ignored in practice resulting in misunderstandings and mutual disbelief of parties involved.  相似文献   

8.
Population and rangelands in Central Tibet: a GIS-Based Approach   总被引：1，自引：0，他引：1  
This study focuses on the meso-regional pattern of rangeland ecotypes in Central Tibet in relation to population density. Data on rangelands derive from a recent land-cover GIS database of China based on the 1:1,000,000 Land Use Map of China. Specific kinds of grassland and steppe are analyzed in relation to 466 township-level enumeration units selected from China's 1990 census in the Tibetan Autonomous Region. This methodology offers a finer geographic resolution than in all other available research reports, and results in a more detailed understanding of the kinds of rangeland resources available to Central Tibetan communities. Systemic land cover patterns are mapped, and reveal the importance of local interactions between population and rangeland ecotypes. Alpine meadow and alpine steppe predominate above the cultivation limit at approximately 4,200 m. In the densely settled valleys below this limit, dry steppe and scrub grassland predominate.  相似文献   

9.
With respect to the great wealth of information available online, the Internet can be viewed as a gigantic database with diverse resources. One of the pressing issues is to investigate the effectiveness and usefulness of the available information over the Internet. This research modeled the population change of Vietnamese-Americans (VA) in Texas from 2000 to 2009 by obtaining web demographic data from the Internet. The project objective is to pilot study a novel approach to conducting online “census” by using Web 2.0 technologies and to investigate the effectiveness of web data for GIS-based demographic application. The solicited VA demographics were geocoded at both county and census tract levels and compared with the Census 2000 demographics in the Geographic Information Systems. Spatial and statistical analyses were used to explore the spatial distribution of VA and to model their population change between 2000 and 2009. The findings of this study include: (1) in general, there are significant differences in the spatial distribution of the VA population between the web demographics and Census 2000 at both county and census tract levels, (2) the Hoover Indices of VA population in Texas at 2000 and 2009 revealed a trend of deconcentration which conforms to the general rural-urban-suburban migration among major metropolitan areas in Texas. This study sheds new insights to using web demographic data for population predictions and applications to plan services for ethnic groups.  相似文献   

10.
The main objective of this study is to devise a method by which one can estimate the number of building units available for use, the purpose of using them and the percentage of vacant units in the city of Riyadh. The raw data for this research were obtained from the Saudi Consolidated Electric Company after being modified by the authorr for the purposes of this work. The analysis of the acquired data shows that Riyadh has witnessed a booming growth in the number of building units. As a result of this tremendous expansion in building and construction, the supply of building units exceeded that of the demand so that some 14% of the building units are left vacant. In the absence of a more recent population census the writer believes that this method may be used to study both land use and population growth and density not only in the city of Riyadh but also in other cities in the Kingdom of Saudi Arabia.  相似文献   

11.
There is no single method available for estimating the seismic risk in a given area, and as a result most studies are based on some statistical model. If we denote by Z the random variable that measures the maximum magnitude of earthquakes per unit time, the seismic risk of a value m is the probability that this value will be exceeded in the next time units, that is, R(m)=P(Z>m). Several approximations can be made by adjusting different theoretical distributions to the function R, assuming different distributions for the magnitude of earthquakes. A related method used to treat this problem is to consider the difference between the times of occurrence of consecutive earthquakes, or inter-event times. The hazard function, or failure rate function, of this variable measures the instantaneous risk of occurrence of a new earthquake, supposing that the last earthquake happened at time 0. In this paper, we will consider the estimation of the variable that measures the inter-event time and apply nonparametric techniques; that is, we do not consider any theoretical distribution. Moreover, because the stochastic process associated with this variable can sometimes be non-stationary, we condition each time by the previous ones. We then work with a multidimensional estimation, and consider each multidimensional variable as a functional datum. Functional data analysis deals with data consisting of curves or multidimensional variables. Nonparametric estimation can be applied to functional data, to describe the behavior of seismic zones and their associated instantaneous risk. The applications of estimation techniques are shown by applying them to two different regions and data catalogues: California and southern Spain.  相似文献   

12.
In this paper, the extent to which the potentially transit-dependent portion of the population is vulnerable to the effects of a hurricane is estimated. The vulnerability of an area is defined as a composite measure of the proportion of disadvantaged persons, distance to transit, and flooding potential of people within an area. Unlike past studies which have focused on the vulnerability of the population in relatively large geographic areas, this study estimates the vulnerability of the population in 30 m × 30 m areas as defined in the National Land Cover Database. Population estimates from the national census at block level are disaggregated to the 30 m × 30 m units using a modified dasymetric mapping method in ArcGIS. The modified mapping method assigns population to each small areal unit using weights estimated by regressing the area of each land use in a census block against the population in that block. The coefficients in the regression analysis are “weights” associating population with each land use, and are used to distribute the population in each census block to the small geographic units based on their land use. In a case study of New Orleans, the results show that some areas are not well served by the existing transit pickup locations, as evidenced by their high vulnerability scores. Reassignment of pickup point locations to cover higher vulnerability score areas was investigated using integer linear programming. The results show that the optimally located pickup points serve areas with a larger average vulnerability score than the current pickup points in the study area. The method appears to be helpful in identifying vulnerable areas that, subsequently, could receive improved hurricane evacuation service in the future.  相似文献   

13.
梁友嘉  徐中民 《冰川冻土》2012,34(4):999-1006
尽管近年来统计数据的生成技术有了很大提高, 但可用的详细人口数据始终难以得到满足.在一些自然-人文要素耦合的建模研究中, 如生态经济集成建模、 环境和健康分析等都需要基于区域尺度的栅格人口分布建模方法.随着GIS和RS技术的发展, 上述建模方法已有较大进步.利用GIS技术, 基于夜间灯光辐射数据和LUCC在象元栅格水平上构建张掖市甘州区人口空间分布. 首先对DMSP夜间灯光辐射数据进行重采样, 通过普通克里金插值获得灯光数据; 然后与LUCC叠加分析, 利用回归分析的方法获取研究区土地利用、 灯光辐射指标和人口统计数据之间的定量关系, 完成空间化.并在乡镇尺度上进行模型检验, 模型总体的调整R2为0.88, 标准误差为400, 为下一步开展时空变化分析提供支持.  相似文献   

14.
Geoelectrical resistivity techniques are increasingly being applied in addressing a wide range of hydrological, environmental, and geotechnical problems. This is due to their effectiveness in near-surface characterization. In the present study, a suite of vertical electrical soundings (VESs) was integrated with 2D geoelectrical resistivity and time-domain induced polarization (IP) imaging to characterize the near-surface and delineate the underlying aquifer in a sedimentary terrain. The geophysical survey was conducted as part of preliminary studies to evaluate the potential of groundwater resource in Iyana-Iyesi and Canaan Land area of Ota, southwestern Nigeria. A high-yield confined sandy aquifer overlain by a low-yield aquitard was delineated; overlying the aquitard is a very resistive and thick layer that is predominantly composed of kaolinitic swelling clay intercalated with phosphate mineral.  相似文献   

15.
During the last 20 years earth-scientists have energetically explained the relevance of environmental geology to, and provided advice for, planning and development. Even so, numerous instances of sterilisation of earth-resources and of development on unstable land with insufficient precautions taken still occur. The reasons for this include: (a) limited training in the earth-sciences for many planners and developers; (b) failure to appreciate the benefits of having sound, easily available background information for decision making; and (c) presentation of results in ways that are not readily understood by potential users or do not fit easily into the administrative processes for land-use planning and development control.

Addressing these issues is at least as important as developing techniques and undertaking new studies, since full and proper utilisation of results and appreciation of the need to commission such research depend on their resolution.  相似文献   


16.
Laser ablation multi-collector mass spectrometry (LA-MC-ICP-MS) has emerged as the technique of choice for in situ measurements of Sr isotopes in geological minerals. However, the method poses analytical challenges and there is no widely adopted standardised approach to collecting these data or correcting the numerous potential isobaric inferences. Here, we outline practical analytical procedures and data reduction strategies to help establish a consistent framework for collecting and correcting Sr isotope measurements in geological materials by LA-MC-ICP-MS. We characterise a new set of plagioclase reference materials, which are available for distribution to the community, and present a new data reduction scheme for the Iolite software package to correct isobaric interferences for different materials and analytical conditions. Our tests show that a combination of Kr-baseline subtraction, Rb-peak-stripping using βRb derived from a bracketing glass reference material, and a CaCa or CaAr correction for plagioclase and CaCa or CaAr + REE2+ correction for rock glasses, yields the most accurate and precise 87Sr/86Sr measurements for these materials. Using the analytical and correction procedures outlined herein, spot analyses using a beam diameter of 100 μm or rastering with a 50–65 μm diameter beam can readily achieve < 100 ppm 2SE repeatability ("internal") precision for 87Sr/86Sr measurements for materials with < 1000 μg g-1 Sr.  相似文献   

17.
Risk management in urban planning is of increasing importance to mitigate the growing amount of damage and the increasing number of casualties caused by natural disasters. Risk assessment to support management requires knowledge about present and future hazards, elements at risk and different types of vulnerability. This article deals with the assessment of social vulnerability (SV). In the past this has frequently been neglected due to lack of data and assessment difficulties. Existing approaches for SV assessment, primarily based on community-based methods or on census data, have limited efficiency and transferability. In this article a new method based on contextual analysis of image and GIS data is presented. An approach based on proxy variables that were derived from high-resolution optical and laser scanning data was applied, in combination with elevation information and existing hazard data. Object-oriented image analysis was applied for the definition and estimation of those variables, focusing on SV indicators with physical characteristics. A reference Social Vulnerability Index (SVI) was created from census data available for the study area on a neighbourhood level and tested for parts of Tegucigalpa, Honduras. For the evaluation of the proxy-variables, a stepwise regression model to select the best explanatory variables for changes in the SVI was applied. Eight out of 47 variables explained almost 60% of the variance, whereby the slope position and the proportion of built-up area in a neighbourhood were found to be the most valuable proxies. This work shows that contextual segmentation-based analysis of geospatial data can substantially aid in SV assessment and, when combined with field-based information, leads to optimization in terms of assessment frequency and cost.  相似文献   

18.
Accurate prediction of the shape, location, size and properties of the solid rock materials to be extracted during mining is essential for reliable technical and financial planning. This is achieved through geological modelling of the three-dimensional (3D) shape and properties of the materials present in mineral deposits, and the presentation of results in a form which is accessible to mine planning engineers. In recent years the application of interactive graphics software, offering 3D database handling, modelling and visualisation, has greatly enhanced the options available for predicting the subsurface limits and characteristics of mineral deposits. A review of conventional 3D geological interpretation methods, and the model struc- tures and modelling methods used in reserve estimation and mine planning software packages, illustrates the importance of such approaches in the modern mining industry. Despite the widespread introduction and acceptance of computer hardware and software in mining applications, in recent years, there has been little fundamental change in the way in which geology is used in orebody modelling for predictive purposes. Selected areas of current research, aimed at tackling issues such as the use of orientation data, quantification of morphological differences, incorporation of geological age relationships, multi-resolution models and the application of virtual reality hardware and software, are discussed.  相似文献   

19.
Prioritization of disaster risk was carried out for a community in Toronto, Canada. Geographic information systems (GIS) were used for spatial analysis, including spatial overlays and clipping for extracting spatial and attribute information related to people’s vulnerability, critical infrastructure and landuse. In order to determine disaster risk, the overall community vulnerability was evaluated by combining social, economic, physical and environmental vulnerabilities. This paper uses the propane explosion incident as the case in point to demonstrate the methodology and procedure used to evaluate risk using GIS techniques. City of Toronto spatial data have been integrated with the study area to gather landuse information, identify risk zones based on the propane storage facility location and evaluate risks. Statistics Canada 2006 census data have been used for area demographics and people’s social and economic status. Vulnerability indicators were determined based on the GIS-derived spatial and attribute data for the hazard and evacuation zones followed by a quantitative spatial risk estimation and ranking. The methodology of this study, based on the risk evaluation and prioritization conducted, can be applied to future decision making in effective landuse planning and the development of risk management strategies.  相似文献   

20.
The uniaxial compressive strength (UCS) of intact rock, which can be estimated using relatively straightforward and cost-effective techniques, is one of the most practical rock properties used in rock engineering. Thus, constitutive laws to represent the strength and behavior of (intact) rock frequently use it, along with additional intrinsic rock properties. Although triaxial tests can be employed to obtain best-fit failure criterion parameters that provide best strength predictions, they are more expensive and require time-consuming procedures; as a consequence, they are often not readily available at early stages of a project. Based on the analysis of an extensive triaxial test database for intact rocks, we propose a simplified empirical failure criterion in which rock strength at failure is expressed in terms of confining stress and UCS, with a new parameter which can be directly estimated from the UCS for a specified rock type in the absence of triaxial test data. Performance of the proposed failure criterion is then tested for validation against experimental data for eight rock types. The results show that strengths of intact rock estimated by the proposed failure criterion are in good agreement with experimental test data, with small discrepancies between estimated and measurements strengths. Therefore, the proposed criterion can be useful for preliminary (triaxial) strength estimation of intact rocks when triaxial tests data are not available.  相似文献   

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