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71.
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
72.
梅州城市空间形态演化及其成因分析 总被引:1,自引:0,他引:1
在把握梅州城市近千年的形成与发展历史的基础上,总结梅州城市空间形态的演化特征,剖析其空间形态演化的成因。受河流的阻碍与切割、行政建制的变迁与政府导向、城市规划的引导与控制、城市的职能转变与规模扩张等多因素的作用和影响,梅州城市空间形态呈"块状-星状-纺锤形-圈层状"演化。梅州城市空间形态的嬗变要满足历史文化名城保护的要求,分散组团状空间形态将是梅州城市空间形态的演化方向。 相似文献
73.
A Simple Single-Layer Urban Canopy Model For Atmospheric Models: Comparison With Multi-Layer And Slab Models 总被引:26,自引:7,他引:26
Hiroyuki Kusaka Hiroaki Kondo Yokihiro Kikegawa Fujio Kimura 《Boundary-Layer Meteorology》2001,101(3):329-358
We developed a simple, single-layer urban canopy model, and comparedit to both multi-layer and slab models. Our single-layer model has thefollowing features: (a) It is a column model of energy and momentumexchange between an urban surface and the atmosphere, (b) it includesthe influence of street canyons, which are parameterized to representthe urban geometry, (c) it includes shadowing from buildings andreflection of radiation, and (d) it estimates both the surfacetemperatures of, and heat fluxes from, three surface types: roof, wall,and road. In the simulation of the single-layer model, the roof washottest during the daytime, but coolest from midnight to early morning.This is consistent with output from the multi-layer model and fieldobservations at a residential area on a clear, summer day. The diurnalvariation of the energy budget from the single-layer model agrees wellwith that from the multi-layer model. Our single-layer model'sperformance is nearly that of a multi-layer model for studyingmesoscale heat islands. Nevertheless, it is simply parameterized,and thus easily included in larger-scale atmospheric models. The slabmodel has the largest nighttime cooling rate of the three models. Toovercome this, it needs more adjustments than for the canopy models. 相似文献
74.
景观生态学在城市规划和管理中的应用 总被引:53,自引:2,他引:53
城市是典型的人工景观,空间结构上属于紧密汇聚型,功能上表现为高能流、高容量和文化上的多样性。城市景观生态研究包括城市空间结构与生态过程,城市景观风貌与城市生态建设,城市景观规划是其最直接的应用。首先论述了城市景观质量与价值评价,包括景观美学评价与景观视觉容量。城市空间结构和景观规划原则是该文论述的主题,包括城市空间布局、城市空间扩展的廊道效应以及城市绿地系统的空间结构分析;以上海和广州市的绿地系统为例进行了重点介绍,最后对于城乡交错带的景观变化进行分析,用景观格局及其动态来描述城乡交错带的城市化过程特点,介绍了上海和沈阳的典型研究。 相似文献
75.
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
76.
城市边缘区景观变化与人为影响的空间分异研究 总被引:38,自引:5,他引:38
利用1988、1993、1998年的遥感影像,应用最大似然法和概率松弛法对马山景观组分进行了测量,在此基础上,对分类结果进行比较求得研究区景观变化的转移短也阵,分析了人为改造活动与景观组分之间的对应关系和空间变化过程,马山区已经从1988年的传统农业景观转化为1998年的城郊混合景观,人口、经济、产业结构均发生了巨大变化,借助人为影响指数,利用网格采样和地统计学分析,研究了马山1988-1998年间景观的人为开发利用活动,揭示人为活动的空间变异强度分布及景观转变过程的社会驱动力。 相似文献
77.
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
78.
79.
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
80.