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81.
常规人口估算方法耗时、费力、财物消耗大且周期长,况且,仅靠少数年份的人口统计资料也是难以准确揭示人口状况的。尽管应用遥感方法估算人口的历史并不长,精度也还不高,但已显示了其优越性。遥感估算人口的主要原理如下。 (1)美国国防卫星及NOAA卫星的热红外通道图像说明,人口分布及其数量与城市耗能量(人工热源)相关,而耗能量又与图像灰度相关;(2)城市人口的膨胀与城市面积的扩展相关;(3)像片上进行住宅计数,用人口普查资料或抽样调查方法确定每户平均人数则可进行人口估算;4)人口密度大小也反映在人工结构物及自然物体的波谱反射率差异上,据此可建立人口数量与反射率的回归方程。 相似文献
82.
Selection of regional historical rainfall time series as input to urban drainage simulations at ungauged locations 总被引:1,自引:0,他引:1
P.S. Mikkelsen H. Madsen K. Arnbjerg-Nielsen D. Rosbjerg P. Harremoës 《Atmospheric Research》2005,77(1-4):4
It has become established practice during the past 20 years to use high-resolution historical rainfall time series as input to hydrological model packages for detailed simulation of urban drainage systems. However, sufficiently long rain series are rarely available from the exact catchment in question and simulations are hence often based on available rain series from other locations. Extreme rainfall properties of importance to the performance of urban storm drainage systems vary significantly even in regions with only minor physiographic differences. Part of this variation can be explained by regional variations of the mean annual rainfall and the remaining statistical residue can be interpreted as statistical uncertainty.In Denmark, more than 75 high-resolution rain gauges are installed across a total area of 43,000 m. About 40 gauges had sufficiently long records to be included in a comprehensive national investigation where newly developed statistical regionalisation procedures were used to model the regional variation of extreme rainfalls. On this basis, a spreadsheet model was made available for estimation of extreme design rainfalls and the associated uncertainty at any location in the country. Statistics were furthermore computed to classify historical rainfall time series according to the developed regional model, and this makes it possible to assess the uncertainty related with using different historical rain series for simulations at ungauged locations.This research indicates that use of historical point rainfall data at ungauged locations introduces a significant uncertainty that is largely overlooked in today's practice. The engineering recommendation is to select historical rain series based on an evaluation of the local physiographic characteristics (e.g., the mean annual rainfall) and a (pre-defined) desired safety level of the simulations. 相似文献
83.
Vulnerability of groundwater in Quaternary aquifers to organic contaminants: a case study in Wuhan City,China 总被引:5,自引:0,他引:5
Yanxin Wang Broder J. Merkel Yilian Li Hui Ye Surong Fu Dana Ihm 《Environmental Geology》2007,53(3):479-484
More than 30 organic contaminants were detected in shallow groundwaters at Wuhan, the largest city in central China. Seriously
contaminated groundwaters were from densely populated, industrial and commercial areas. Abnormal concentrations were found
in groundwater from Hankou, downtown Wuhan: trimethylbenzene up to 29 μg/L, tetramethylbenzene up to 866 μg/L, and trichloroethene
up to 9.5 μg/L. Benzene, Toluene, Ethylene and Xylene (BTEX) contamination of groundwater is serious and widespread at Wuhan,
ranging between 0.14 and 25.0 μg/L. Considering the hydrogeological conditions of most Chinese cities, DRAMIC, a modified
version of the widely used DRASTIC model, was proposed by the authors for assessing vulnerability of groundwater to contamination.
The factors D, R, A and I in DRAMIC model are the same as in DRASTIC. The factor topography is ignored. The factor soil media is substituted by a new factor aquifer thickness (M) and the factor hydraulic conductivity of the aquifer by a new factor impact of contaminant (C). The equation for determining the DRAMIC Index is: DRAMIC = 5D
R + 3R
R + 4A
R + 2M
R + 5I
R + 1C
R. The calculated DRAMIC Index can be used to identify areas that are more likely to be susceptible to groundwater contamination
relative to each other. The higher the DRAMIC Index is, the greater the groundwater pollution potential. Applying DRAMIC,
a GIS-based vulnerability map for Wuhan city was prepared. Interestingly, places such as downtown Hankou, where enhanced concentrations
of BTEX have been detected, correspond quite well with those with higher DRAMIC ratings. 相似文献
84.
中国农村转型与耕地保护机制 总被引:122,自引:10,他引:122
我国农村和城市的发展都处在转型时期,对土地的需求将进一步扩展,而开发边际土地的余地已经有限,未来耕地食物安全的形势将更趋势严峻,因而保护耕地成为我国的基本国策,但实际上由于缺乏保护机制,耕地仍在继续向效益更高的其它土地用途转移,因此,保护耕地的根本大计在于建立机制,保护耕地的经济机制是提高农业的比较经济效益,耕地生态服务功能的价值实现至关重要,在政策管理机制方面,要强化政府在耕地保护中的作用,规范土地管理行为,明确独立于市场的政府土地管理目标,并以法律形式固定的规划作为实现目标的手段,城市发展要加强内涵集约度。 相似文献
85.
Ecological conflicts in Poland 总被引:1,自引:0,他引:1
Transformation of the political system, observed in Poland for 10 years in connection with economic restructuring and basic
socio-economic reforms to harmonise with European Union structures, is also evident in terms of environmental management.
Pollution has been reduced in many ways but the rise in living standards, linked with the rapid growth of cars and other forms
of consumption, has had a negative effect and environmental conditions have deteriorated in the central areas of large cities.
The growth of waste water and refuse is a considerable problem. More areas are now officially protected and the three levels
of local government established at the beginning of January 1999 (voivodeship, district and community) all have certain defined
environmental protection responsibilities which are cumulatively greater than before. Meanwhile there is a greater awareness
in society of environmental issues, although it does not yet lead to a high level of participation in protection work. However,
there are strongly-expressed opinions on the ecological acceptability of certain economic developments and conflicts are frequently
arising within communities and local governments and also between investors on the one side and ecological organisations and
environmental protection institutions on the other. Most controversial are new roads, power stations (like the Zarnowiec nuclear
project) and reservoirs like the one on the Dunajec river at Czorsztyn. Local communities frequently resist plans for waste
dumps, incinerating plants and other developments which are seen as injurious to health or the quality of life. The planned
reprivatisation of the state-owned forests is also criticised by foresters and ecological movements. Conflicts are likely
to grow as economic development accelerates but better information and greater public understanding of the need for sustainability
should make for consensus.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
86.
A. F. Howland 《Engineering Geology》2001,60(1-4):117-125
A process of urban regeneration of the former industrial dock area of east London by the London Docklands Development Corporation (LDDC) recognised the importance of geotechnical and geoenvironmental information. A systematic programme of data collection was implemented and stored in a series of bespoke computer database systems and cartographic registers. These allowed retrieval and manipulation of the data to provide rapid site assessments. The understanding of the natural setting of the area was enhanced as a consequence of the collation exercise. The data stored included geotechnical and environmental information on soil and groundwater. The hydrogeological regime was modelled by computer to determine the consequences of development on groundwater movement. In addition, a cartographic register of historic land use was developed. This gave instant detail on the potential for contamination of a site and became a fundamental tool in the UK planning process of the area. The information from the separate systems was finally combined into a geographic information system. 相似文献
87.
88.
广州信息密集服务业的空间发展及其对城市地域结构的影响 总被引:27,自引:0,他引:27
采用第三产业普查资料,深入分析了改革开放以来广州信息密集服务业的发展水平,空间发展特征和原因及其对城市地域结构的影响,揭示了信息密集服务业发展与城市地域运动的关系。 相似文献
89.
90.
Hung Tran Daisuke Uchihama Shiro Ochi Yoshifumi Yasuoka 《International Journal of Applied Earth Observation and Geoinformation》2006
This study focuses on using remote sensing for comparative assessment of surface urban heat island (UHI) in 18 mega cities in both temperate and tropical climate regions. Least-clouded day- and night-scenes of TERRA/MODIS acquired between 2001 and 2003 were selected to generate land-surface temperature (LST) maps. Spatial patterns of UHIs for each city were examined over its diurnal cycle and seasonal variations. A Gaussian approximation was applied in order to quantify spatial extents and magnitude of individual UHIs for inter-city comparison. To reveal relationship of UHIs with surface properties, UHI patterns were analyzed in association with urban vegetation covers and surface energy fluxes derived from high-resolution Landsat ETM+ data. This study provides a generalized picture on the UHI phenomena in the Asian region and the findings can be used to guide further study integrating satellite high-resolution thermal data with land-surface modeling and meso-scale climatic modeling in order to understand impacts of urbanization on local climate in Asia. 相似文献