城乡边缘带时空离心推移的约束及其方法     

龚兆先  温春阳  周永章 《热带地理》2006,26(2):129-133

分析了城乡边缘带时空离心推移的驱动力,认为必须而且可以对离心推移进行适当约束,以促进城乡边缘带的可持续发展;分析了离心推移的约束机制及约束的基本方式,提出了约束的主要原则和主要方法。  相似文献   

国外都市农业发展经验对我国的启示   总被引：15，自引：0，他引：15  

刘长运 《世界地理研究》2006,15(2):74-79

国外都市农业发展较早,积累了相当多的经验,而我国都市农业仍属新生事物。笔者简要介绍了日本、德国、新加坡和荷兰发展都市农业的成功做法和经验,进一步分析了都市农业的基本功能,并结合我国国情提出了六个方面的措施与建议,即:科学规划,合理布局;加强政府对都市农业的支持力度;拓宽投资、融资渠道;提高都市农业的科技含量,扩大都市农业园区的规模;高度重视观光休闲农业的建设和发展;加强宣传,转变观念。  相似文献   

城市河岸土地利用对河流廊道功能影响初探——以上海苏州河为例   总被引：1，自引：0，他引：1  

陈婷  杨凯 《世界地理研究》2006,15(3):82-87

城市河岸土地利用往往改变河岸的自然地理条件,对城市河流功能产生影响。通过总结城市河岸廊道功能以及国内外城市河岸规划土地利用的实践,分析了河岸土地利用对城市河流廊道功能的影响,并以上海苏州河为例进行了实证分析。结果表明,苏州河河岸规划土地利用方式提高了河岸开放带宽度,改善了河岸舒适性,控制了河岸建筑高度,有利于保护和开发苏州河河流的景观、遗产和经济廊道的功能。干流河岸在自然廊道功能方面,仍存在一定缺陷,与支流的部分河段相比仍有差距。  相似文献   

Urban lightning climatology and GIS: An analytical framework from the case study of Atlanta, Georgia     

J. Anthony Stallins  Mace L. Bentley 《Applied geography (Sevenoaks, England)》2006,26(3-4):242-259

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Geomorphic effects of rural-to-urban land use conversion on three streams in the Central Redbed Plains of Oklahoma   总被引：2，自引：1，他引：2  

Ranbir S. Kang  Richard A. Marston   《Geomorphology》2006,79(3-4):488

This research evaluates the impact of rural-to-urban land use conversion on channel morphology and riparian vegetation for three streams in the Central Redbed Plains geomorphic province (central Great Plains ecoregion) of Oklahoma. The Deep Fork Creek watershed is largely urbanized; the Skeleton Creek watershed is largely rural; and the Stillwater Creek watershed is experiencing a rapid transition from rural to urban land cover. Each channel was divided into reaches based on tributary junctions, sinuosity, and slope. Field surveys were conducted at transects in a total of 90 reaches, including measurements of channel units, channel cross-section at bankfull stage, and riparian vegetation. Historical aerial photographs were available for only Stillwater Creek watershed, which were used to document land cover in this watershed, especially changes in the extent of urban areas (impervious cover).The three streams have very low gradients (< 0.001), width-to-depth ratios < 10, and cohesive channel banks, but have incised into red Permian shales and sandstone. The riparian vegetation is dominated by cottonwoods, ash, and elm trees that provide a dense root mat on stream banks where the riparian vegetation is intact. Channels increased in width and depth in the downstream direction as is normally expected, but the substrate materials and channel units remained unchanged. Statistical analyses demonstrated that urbanization did not explain spatial patterns of changes in any variables. These three channels in the central Redbed Plains are responding as flumes during peak flows, funneling runoff and the wash-load sediment downstream in major runoff events without any effect on channel dimensions. Therefore, local geological conditions (similar bedrock, cohesive substrates and similar riparian vegetation) are mitigating the effects of urbanization.  相似文献   

Comparison of magnetic parameters with vehicular Br levels in urban roadside soils     

Xue-Song Wang  Yong Qin 《Environmental Geology》2006,50(6):787-791

Chemical methods are generally chosen to monitor soil pollution but magnetic measurements proved to yield additional information at low cost and less time consumption. In this investigation, the novel use of rapid and non-destructive magnetic measurements to characterize Br levels in Xuzhou (China) urban roadside soils was reported. X-ray fluorescence spectrometry (XRF) was used to quantify Br in the soil samples. Data from 21 roadside soil samples confirm Br contamination, with a mean level of 4.36 mg kg⁻¹ and a range of 2.4–8.7 mg kg⁻¹. These values are higher than that of unpolluted soils in Xuzhou that averages 1.1 mg kg⁻¹. Hierarchical clustering analysis shows Br in Xuzhou roadside soils is mainly from road traffic. Clear correlations between Br levels and simple magnetic parameters [mass specific susceptibility (χ _LF), susceptibility of anhysteretic remanent magnetization (χ _ARM), saturation isothermal remanence (SIRM)] are observed. The present study shows that these three magnetic parameters can be used as a proxy for Br levels in Xuzhou urban roadside soils.  相似文献   

Groundwater and highways interaction: past and present experiences of highway construction in Slovenia     

Mihael Brencic 《Environmental Geology》2006,49(6):804-813

During the planning, designing, construction, operation and maintenance of highways, groundwater can be of important environmental and constructional constraint that can significantly influence the safety operation of traffic and of big influence on the operational costs of highways. To classify and conceptualize the relation between groundwater and highways, three important groups of problems can be determined: groundwater protection from highway influences, protection of highway from groundwater and economic use of groundwater for highway operation. In the present study, groundwater management strategies are represented during all life cycles of highways. Greater emphasis is given to groundwater protection and field hydrogeological investigations for proper groundwater management related to the highway. The approach adopted in Slovenia and the role of hydrogeology is given as an illustration.  相似文献   

论信息时代的城市发展     

金江军  潘懋  承继成 《国土资源信息化》2005,20(2):2-5,41

城市信息化是中国城市发展的新主题与新动力,是解决目前我国城市发展中诸多难题的重要途径。本文首先对比了数字城市和信息城市,然后指出了建设信息城市的迫切性和重要性,最后提出了城市信息科学的学科范畴。  相似文献   

基于GIS的城镇土地定级信息系统建模方法探讨   总被引：2，自引：0，他引：2  

刘艳中  汪新庆 《国土资源信息化》2005,19(3):37-40

基于GIS的城镇土地定级信息系统在建设过程中,定级方法确定、定级单元大小确定和定级因素/子权重值的生成是关键,且三者都具有不同的确定方法,因此选择什么样的方法决定了系统建立的优劣。本文着重归纳、总结了城镇土地定级信息系统定级方法,通过对比分析,探讨了最优定级方法、最优网格单元大小划分方法和最优因素/子权重值计算方法。  相似文献   

北京夏季城市热岛现状及楔形绿地规划对缓解城市热岛的作用   总被引：20，自引：2，他引：20       下载免费PDF全文

佟华  刘辉志李延明桑建国胡非 《应用气象学报》2005,16(3):357-366

通过遥感技术与地面测定相结合的方法，对北京城市热岛现状作观测研究，得到北京城市地面的温度分布特点。使用北京大学城市边界层模式从气象观点就“楔形绿地”规划对北京城市气候的影响进行研究和评价，模式通过对城市地表复杂性和多样性的特征进行细致描述，建立了一个细致模拟城市特点的城市边界层能量平衡模式，并用此能量平衡模式得到的地面温度作为下边界条件，中尺度气象模式MM5做初始场和侧边界条件，建立一个最小分辨率为500 m的城市边界层模式系统，来研究城市边界层在中尺度背景场作用下的精细结构。通过个例模拟，模式能够较准确地模拟城市边界层的风温场分布情况，可以用来对楔形绿地规划进行模拟试验。通过对规划后的气象场在特定的气象条件下进行模拟，结果显示，建造大型的楔形绿地后，绿地区域及绿地周围约1 km以内的地区温度有所降低，降低的程度由规划前后的地表类型改变的剧烈程度、风速大小及与绿地的距离决定，但是这种规划方案却会因城市的下风方向的风速减小而导致通风不畅。  相似文献