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641.
河流水质评价中模糊数学评价法的应用与比较 总被引:8,自引:0,他引:8
选择2005年6个典型日(1月12日、3月10目、5月10日、7月13日、9月8日和11月10日)的水质,运用两种模糊数学评价法对浙江西苕溪流域港口断面的水质进行评价并作比较。第一种数学评价法采用较为简单的单因素模糊综合评价法,另一种采用多级模糊数学评价法。评价结果表明,1月12日、3月10日和11月10日的水质达到国家Ⅰ类水质标准;而5月10目的水质相对最差。比较两种评价方法,单因素模糊综合评价法对单个因素的影响敏感,特别是超标值对最后的相对隶属度贡献大;而多级模糊评价法综合各个因素来评价现状水质,因而反映出水质的综合情况。结合港口断面的特点分析水质变差的原因,结论是:流域农业劳作带来的面源污染物质进入港口断面使得该断面在农作高峰期水质较差;同时,断面的水资源短缺问题较为严重,导致水环境容量较小,污染物较难稀释扩散。 相似文献
642.
城市洪水是我国城市灾害中危害最大的一种灾害,文章侧重从自然地理条件与人为因素两个方面分析我国城市洪水灾害的成因,最后有针对性的提出了我国城市防洪的软、硬件工程措施。 相似文献
643.
JIN Lei 《中国减灾(英文版)》2001,(3)
1Introduction of urban industrial disastersAt the Ministers' Forum on Disaster Reduction and Economic Development in China held on1March2 0 0 0 ,Deputy Director-General YANG Fu of the State Commission of Economy and Tradeemphasized by saying:" Security is importantnotonly to individual life,butalso to social stabilityand economic development. Among the 1 1 8catastrophic accidents in China in 1 999,each ofwhich caused the death of more than ten people,over70 % were connected with urban… 相似文献
644.
在蓬勃发展的城市化进程中,一方面,城市交通需求迅速增长,交通运输供给能力不足成为制约区域经济快速发展的瓶颈;另一方面,在城市化进程中突出的景观标志--土地利用的变化包含着城市极其丰富的信息量,城市交通网络设计必然要求将城市土地利用与交通网络设计整合考虑.概述了土地利用与交通网络设计的关系,构建了一个基于GIS的城市土地利用与交通网络设计一体化模型 (LTGIS) ,同时对模型中的系统设计进行了论述,表明城市土地利用与交通网络设计是密切相关的.基于GIS的城市土地利用与交通网络设计一体化模型(LTGIS)的提出具有理论与实践的双重意义. 相似文献
645.
William O. Rasmussen Peter F. Ffolliott 《Journal of the American Water Resources Association》1981,17(6):1079-1082
ABSTRACT: Generally a difference exists between the horizontal planar area of a watershed as measured on a map and the actual surface area. A technique is presented, utilizing a topographic map, for computing the difference in the two areas as well as yielding a prediction of the actual surface area. Spatial variations in the magnitude of the difference in the two areas for small local sites over the watershed are displayed on computer generated maps. The technique is also used to adjust various inventory variables on maps, such as vegetation density, to reflect actual surface coverage. This allows estimates to be made of the difference in using corrected versus uncorrected area related parameters in mathematical functions describing processes occurring in the atmosphere-surface boundary layer. 相似文献
646.
Evaluating the characteristics of a set of sites as potential scientific research reserves is an example of land suitability
assessment. Suitability in this case is based upon multiple criteria, many of which can be linguistically imprecise and often
incompatible. Fuzzy logic is a useful method for characterizing imprecise suitability criteria and for combining criteria
into an overall suitability rating. The Ecosystem Management Decision Support software combined a fuzzy logic knowledge base
we developed to represent the assessment problem with a GIS database providing site-specific data for the assessment. Assessment
of sites as a potential natural reserve for the new University of California campus at Merced demonstrates the benefits of
fuzzy suitability assessment. The study was conducted in three stages of successively smaller assessment regions with increasingly
fine spatial resolution and specificity of criteria. Several sites were identified that best satisfy the suitability criteria
for a reserve to represent vernal pool habitat. 相似文献
647.
648.
山东半岛城市群中心城市城市化水平综合评价 总被引:1,自引:0,他引:1
城市化是一种复杂的社会经济现象,受到多方面的影响,单一的指标不能清楚地反映一个城市的综合发展水平,对城市化的评价应建立综合的评价体系。以山东半岛8个地级城市为例,建立指标系,运用数学模型对各城市的城市化进行了综合评价,客观地反映了各城市发展的优劣,最后提出了各城市在未来城市建设方面的建议。 相似文献
649.
五箱一体化活性污泥工艺采取交替运行方式,不需要污泥和混合液回流,良好的循环周期设置对系统至关重要,通过试验研究对不同循环周期设置时的处理效果进行了比较,对主体段进水池状态进行了跟踪试验,结果表明,在水力停留时间和泥龄分别为13 h、18 d的条件下,主体段按120 min设置时能形成良好的厌氧释磷条件,磷的释放率达到0.88 gP/kg MLSS·h,主体段、过渡段和沉淀段分别按120、60和60 min的周期设置时TP、TN的去除率达到90%以上. 相似文献
650.
We introduce climate impact response functions as a means for summarizing and visualizing the responses of climate-sensitive
sectors to changes in fundamental drivers of global climate change. In an inverse application, they allow the translation
of thresholds for climate change impacts (‘impact guard-rails’) into constraints for climate and atmospheric composition parameters
(‘climate windows’). It thus becomes feasible to specify long-term objectives for climate protection with respect to the impacts
of climate change instead of crude proxy variables, like the change in global mean temperature. We apply the method to assess
impacts on terrestrial ecosystems, using the threat to protected areas as the central impact indicator. Future climate states
are characterized by geographically and seasonally explicit climate change patterns for temperature, precipitation and cloud
cover, and by their atmospheric CO2 concentration. The patterns are based on the results of coupled general circulation models. We study the sensitivity of the
impact indicators and the corresponding climate windows to the spatial coverage of the analysis and to different climate change
projections. This enables us to identify the most sensitive biomes and regions, and to determine those factors which significantly
influence the results of the impact assessment. Based on the analysis, we conclude that climate impact response functions
are a valuable means for the representation of climate change impacts across a wide range of plausible futures. They are particularly
useful in integrated assessment models of climate change based on optimizing or inverse approaches where the on-line simulation
of climate impacts by sophisticated impact models is infeasible due to their high computational demand.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献