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301.
Christopher J. Woltemade Timothy W. Hawkins Claire Jantz Scott Drzyzga 《Journal of the American Water Resources Association》2020,56(3):507-527
Changing climate and land cover are expected to impact flood hydrology in the Delaware River Basin over the 21st Century. HEC‐HMS models (U.S. Army Corps of Engineers Hydrologic Engineering Center‐Hydrologic Modeling System) were developed for five case study watersheds selected to represent a range of scale, soil types, climate, and land cover. Model results indicate that climate change alone could affect peak flood discharges by ?6% to +58% a wide range that reflects regional variation in projected rainfall and snowmelt and local watershed conditions. Land cover changes could increase peak flood discharges up to 10% in four of the five watersheds. In those watersheds, the combination of climate and land cover change increase modeled peak flood discharges by up to 66% and runoff volumes by up to 44%. Precipitation projections are a key source of uncertainty, but there is a high likelihood of greater precipitation falling on a more urbanized landscape that produces larger floods. The influence of climate and land cover changes on flood hydrology for the modeled watersheds varies according to future time period, climate scenario, watershed land cover and soil conditions, and flood frequency. The impacts of climate change alone are typically greater than land cover change but there is substantial geographic variation, with urbanization the greater influence on some small, developing watersheds. 相似文献
302.
Urban rail network safety is a critical sector of urban public safety. However, there is no uniform standard for the safety evaluation of the urban rail network. This paper presents a novel methodology by integrating a multilevel decision tree with a fuzzy analytical approach to enhance urban rail network safety. The proposed methodology overcomes serious limitations such as subjectivity in the data and independence of the variables in decision-making processes. The proposed methodology is applied to the risk evaluation of the selected Chongqing rail transit lines and the Expo Line. The risk analysis is considered using the field data collected from these transit lines. The applied case studies confirm the general applicability of the methodology and the multilevel decision tree network. The main risk factors identified for the Chongqing rail traffic system are the terrorist threat, emergency management, and aging infrastructure which need to be investigated as a priority to mitigate risk associated with these infrastructures. 相似文献
303.
The relationship between light and perceived safety at night is intuitively strong, yet theoretically and empirically its workings are largely unknown. Intelligent dynamic road lighting, which continuously adapts to the presence and behavior of users, can light the street only when and where it is needed. As such, it offers a solution to the energy waste and luminous pollution associated with conventional road lighting. With this innovation, however, new questions emerge about the effect of lighting on perceived safety. We need to consider not only how much lighting pedestrians need to feel safe, but also which parts of the street should be lit. In two experiments, we investigated the effect of different light distributions on perceived safety, and explored mediation by people's appraisal of three safety-related cues suggested in the literature: prospect (having an overview), escape (perceived escape possibilities), and refuge/concealment (perceived hiding places for offenders). Both experiments, one with stationary and one with walking participants, demonstrated that people prefer having light in their own immediate surroundings rather than on the road that lies ahead. This could be explained, partially, by changes in prospect, escape, and concealment. Against expectations, prospect was higher with lighting distributions in which participants' immediate surroundings, but not the more distant parts of the road, were most strongly lit. 相似文献
304.
305.
基于RS/GIS的武汉市九峰城市森林保护区景观结构特征及规划对策 总被引:2,自引:0,他引:2
大型的城市森林绿地是城市生态框架的重要组成部分,其景观结构的优化有助于城市生态系统结构与功能稳定。九峰城市森林保护区是武汉近郊最大的森林绿地。应用快鸟遥感影像并结合实地调查,在RS和GIS的支持下对九峰城市森林保护区的景观结构进行了分析,并探讨了森林景观的规划对策。结果表明:九峰城市森林保护区景观分为林地、农耕地、苗圃地、水域、建设用地、墓地、荒地、草地和裸岩9个景观类型,263个斑块,其中林地最多,占总面积的36.56%,占斑块总数的8.75%,为景观基质,但对景观过程的控制作用不强。建设用地和农耕地斑块形状最为复杂,易造成人类活动干扰的扩散。林地成片分布,破碎化程度较低,连通性较高,有利于其资源保护。九峰城市森林保护区表现出整体结构简单,局部结构复杂的特征。针对这些景观结构特征,提出了大幅提高林地比例,压缩建设用地和其他人类活动明显的景观类型面积,构建聚集间有离析的空间优化格局,加强荒地和裸岩的植被恢复,设置“踏脚石”斑块和建立保护性廊道的景观优化对策,以期为九峰城市森林保护区的规划与管理提供依据。 相似文献
306.
Martina Artmann 《Ambio》2014,43(4):530-541
Soil sealing has negative impacts on ecosystem services since urban green and soil get lost. Although there is political commitment to stop further sealing, no reversal of this trend can be observed in Europe. This paper raises the questions (1) which strategies can be regarded as being efficient toward ecologically sustainable management of urban soil sealing and (2) who has competences and should take responsibility to steer soil sealing? The analyses are conducted in Germany. The assessment of strategies is carried out using indicators as part of a content analysis. Legal-planning, informal-planning, economic-fiscal, co-operative, and informational strategies are analyzed. Results show that there is a sufficient basis of strategies to secure urban ecosystem services by protecting urban green and reducing urban gray where microclimate regulation is a main target. However, soil sealing management lacks a spatial strategically overview as well as the consideration of services provided by fertile soils. 相似文献
307.
308.
2000年全球气象灾害评价 总被引:3,自引:0,他引:3
2000年,全球气候持续较常年偏暖。赤道中,东太平洋地区强拉尼娜事件在1月再次达到峰值后,迅速减弱,强拉尼娜事件对全球,特别是对热带地区产生了较大的影响,北半球许多地区冬季出现严寒天气,夏季又遭热浪袭击,严重的高温、干旱、森林大火困扰全球。而亚洲南部、西欧、南部非洲、南美北部的许多地区暴雨频繁。估计气象自然灾害造成全球经济损失达上千亿美元。数亿人口受灾。 相似文献
309.
The air temperature distributions in August (summer) and December (winter) were measured in an approximately 15 × 15-km urban
area in Hyogo Prefecture, Japan, in order to study the spatial distribution of the air temperature and to propose effective
measures against the heat island phenomenon. The air temperature was measured mainly by using thermometer shelters installed
in an elementary school and a junior high school. The characteristic air temperature distribution depended on the season.
The air temperature was higher inland than in the coastal region in August but was higher in the coastal region in December.
The air temperature index indicated that the area where higher air temperatures would most likely appear was 5 to 10 km inland
from the coast in August and around the coast in December. The seasonal air temperature distribution was presumably due to
the strength of solar radiation and anthropogenic exhaust heat. 相似文献
310.
Yannopoulos PC 《Environmental monitoring and assessment》2007,135(1-3):163-180
An economic and quick methodology for performing a preliminary spatial assessment of a city air quality with the purpose to
identify locations and zones susceptible to high pollution levels is proposed. A Patras case-study is selected, regarding
the air pollutants of sulfur dioxide (SO2) and oxides of nitrogen (NOx). A total number of 451 samples of short duration, of which 225 were randomly picked in morning rush hours and 226 within
evening rush hours, were collected from 50 locations of the major Patras area during a year period, when peaks of primary
air pollutants usually occur. Concentration measurements at prescribed locations used to statistically calculate spatial average
concentrations approximating 1-h mean values with mean probable errors less than 25.9% for SO2, NO and NOx and less than 15.5% for NO2. Then iso-concentration contour diagrams plotted indicate high pollution zones and possibly appropriate locations for continuous
or random monitoring according to the European Community (EC) Directives. The 1-h mean concentrations were in good correlation
to the corresponding traffic rates and useful relationships are given (0.54 ≤ r ≤ 0.63). In addition, comparisons with data available for other cities, as well as with the limit and guide values provided
by the EC and the World Health Organization (WHO) were given. The present data could be useful for the design and optimization
of a city network of stations for monitoring air quality, for environmental impact assessments, future reference and comparisons
due to city development needs, as well as for validating dispersion models. 相似文献