Assessing the visual quality of rural villages in China,compared to urban residential areas

Traditional villages in China show a pattern of ‘self-organization’. There is unplanned overall layout of space elements within the village landscape. Since the ‘Building a New Countryside’ policy, professionals have been active in design of the village landscape. The first step is to identify the distinguishing features of the traditional village landscape. This paper aims to identify the distinguishing features of village landscape compared with an urban residential area. The results indicate that abundant plants, shabby houses, monotonous colour, badly-maintained environment and closed space are the distinguishing features. A clean environment and high vegetation coverage are important.     

Surface stormwater hazard assessment in steep urban areas. Case of the city of Mendoza,Argentina

The current paper focusses on the hazard assessment associated with urban runoff on streets. A review of the existing criteria to evaluate such a hazard is made. Two new criteria based on theoretical analysis of the water's force acting on a static pedestrian are presented: no slipping criterion and stability to tilt criterion. According to these criteria, either a maximum depth, or a maximum velocity or some relation between depths and velocities should be fulfilled in order to guarantee the pedestrian's and driver's safety in the case of medium to large storms. A one-dimensional numerical model is used to solve the urban storm runoff within a street network. This model is applied to an urban watershed of the city of Mendoza (Argentina), obtaining the runoff values belonging to return periods of 5, 10 and 25 years. The results are evaluated bearing in mind four hazard criteria. In conclusion, the numerical model is shown to be a useful tool in relation to the application of the hazards criteria. It is also conclude that an effort should be made to determine specific hazard criteria based on experimental data.     

Spatial distribution of total Hg in urban soils from an Atlantic coastal city (Aveiro, Portugal)

The aim of this study was to investigate the levels and the spatial distribution of total Hg concentrations in soils from the urban area of Aveiro (Portugal) in order to assess the impact of industrial activities and identified Hg emission sources in these urban soils. For this purpose, soils were collected in 25 sampling points (at two depths) within the urban perimeter and in places considered representative of the main green areas of the city. A median concentration of 0.091 mg kg(-1) (dry weight) was obtained, regardless the depth. Aveiro was considered a low polluted city in terms of total Hg and no direct effects of emissions of Hg from industrial activities nearby could be detected in these urban soils. Despite of the low values obtained, high variability (range of approximately 0.5 mg kg(-1)) was observed in the results. Such was considered to be related to characteristic features of soils in urban settings and to the behaviour of Hg in the urban environment.     

Accumulation and wash-off characteristics of surface pollutant and identification of risk areas on urban land uses in a lakeside city,Wuxi, China

ABSTRACT

This paper selected administration and public services, residential areas, roads, green space, parking areas, industrial areas and commercial and business facilities in Wuxi city, China, to analyze the characteristics of pollution accumulation, wash-off and potential risk areas of pollutants over different urban land uses and pavement surface materials. Results showed that green space, residential areas and roads sequestrated higher pollutants than that of other land uses. Materials of masonry and cement pavement accumulated higher pollutant concentration than that on the marble and asphalt pavement. The potential risk areas of non-point source pollution were located in the old residential areas in the downtown region. The results of wash-off simulation showed that the first flushing effect was obvious during the initial period of rainfall. Eighty percent of the accumulative total nitrogen or total suspended solid could be washed-off during the first 25.6–50.2% period of the rainfall events.     

Influence of urban geometry on outdoor thermal comfort in a hot dry climate: A study in Fez,Morocco

There are few studies on the microclimate and human comfort of urban areas in hot dry climates. This study investigates the influence of urban geometry on outdoor thermal comfort by comparing an extremely deep and a shallow street canyon in Fez, Morocco. Continuous measurements during the hot summer and cool winter seasons show that, by day, the deep canyon was considerably cooler than the shallow one. In summer, the maximum difference was on average 6 K and as great as 10 K during the hottest days. Assessment of thermal comfort using the PET index suggests that, in summer, the deep canyon is fairly comfortable whereas the shallow is extremely uncomfortable. However, during winter, the shallow canyon is the more comfortable as solar access is possible. The results indicate that, in hot dry climates a compact urban design with very deep canyons is preferable. However, if there is a cold season as in Fez, the urban design should include some wider streets or open spaces or both to provide solar access.     

Living in the big city: Effects of urban land-use on bird community structure, diversity, and composition

Cities represent an important threat to biodiversity at different scales. Nevertheless, little is known on the processes underlying such effects. In this paper we describe bird diversity, structure, and composition patterns in different urban land-use categories. For this, we surveyed resident bird communities in four representative land-use categories of southwestern Mexico City. Our results show that bird communities vary greatly along the different studied urban land-uses, which represent an urbanization development gradient. Bird communities were highly dominated by few generalist species in areas with commercial components, while showed to have higher evenness values in green areas. Bird species richness decreased and bird abundances increased with urbanization intensity. Also, our results indicate that bird species richness and abundance values are sensible to site-specific habitat characteristics. Although we did not find a clear pattern of taxonomic homogenization related to urbanization, our results show that urbanization development entails the functional homogenization of bird communities. Thus, based on our results, we suggest three urban planning and management activities: (1) regulate land-use change related to urbanization; (2) increase the number of green areas within the city; (3) establish bird monitoring programs to identify focal areas that need management and assist with ecological data for urban planning.     

Application of exceedance probability based on wind kinetic energy to evaluate the pedestrian level wind in dense urban areas

In the present study, assessment of wind environment within the pedestrian level domains of highly populated areas is carried out. Three typical models of a dense urban area are considered and numerically simulated in order to examine the effects of the geometry of such models on wind flow characteristics within the pedestrian domain of a street canyon located within this area. The calculated flow fields are employed to estimate the exceedance probabilities within the study domain using a new approach: average wind kinetic energy. The study is applied to Tokyo, Japan; based on its mean wind velocity data. The results demonstrate that the exceedance probability analysis of the pedestrian wind environment could be a valuable tool for assessing urban areas. Also, the calculated probabilities demonstrate substantial dependence on both the geometry of building arrays and the wind conditions of the considered domain.     

The effects of changes to the post-socialist urban planning framework on public open spaces in multi-story housing areas: A view from Nis,Serbia

This study considers how changes to the post-socialist urban planning framework have affected the treatment of public open space in the transformation of existing mass-housing areas and newly developed multi-story housing areas for the city of Nis, Serbia. The study focuses on quantitative and qualitative changes as well as the physical characteristics of public open spaces, evaluating environmental comfort, safety, accessibility, privacy and intensity of social interactions. The investigation is based on a comparative analysis of three case studies in Nis, which are representative of different developmental, institutional and planning periods. The research indicates a regressive approach in the planning for and treatment of public open space. It also suggests that within the limited economic capacity of local authorities, investors and buyers, the market-oriented post-socialist urban planning framework can lead to spatial and functional fragmentation in housing areas and the degradation or disappearance of not only the public spaces but of open spaces in general.     

Investigation and consideration on landslide zoning of multiple slope failures and debris flows of 2014 disaster in Hiroshima,Japan

This study was intended to examine the mechanism of multiple slope failures and debris flows that occurred in the outskirts of Hiroshima on 20th August 2014. A field survey of the mountain stream where large-scale damage was incurred was carried out and the characteristics of debris flows which made serious damages were investigated. There were five findings of this study. (1) The initiation of debris flows was not limited to thin and planar shallow failures, but also showed V or U shapes, where the eroded sediments seemed to be pushed out by artesian water, and the eroded depth exceeded several meters at many locations. (2) There were areas with high permeability, such as faults, fracture zones, and joints in Mt. Abusan. It is inferred that the constantly present groundwater in these areas became artesian water because of a large amount of rainfall in upstream locations. This quickly destabilized the slopes on a large scale. (3) There were at least three estimated debris flows at the mountain stream above Midorigaoka prefectural apartments in Yagi 3-Chome, where the worst damage occurred. The mountain stream near Abu-no-Sato housing complex also had multiple debris flows. Here, the secondary debris flow changed its flow path because of the presence of sediments from an earlier debris flow. (4) The actual volumes of flowed mass were much larger than that predicted at 11 of the 18 mountain streams in Midori-i and Yagi districts. The volume of the mass of five of these mountain streams was more than twice the estimated volume. It is necessary to modify the method of calculating the volume of unstable sediments in the mountain stream. (5) It was found that the devastating damage of buildings and human lives took place in the areas well beyond the special restricted zones. The present method to designate the special restricted zone must be revised considering such problems as the underestimation of the volume of unstable sediments, the assumptions of a single debris flow and on the direction of debris flow, and the effect of the difference on rock and soil types.     

基于山区水文地质条件下燃煤电厂贮灰场地下水生态环境影响预测

基于我国以煤炭为主的能源结构,火力发电厂仍然在发电领域占有绝对的统治地位。但与此同时,火力发电的副产品粉煤灰堆放问题日益成为社会性问题。由于京津冀地区空气和地下水污染防控的巨大压力,环保问题成为困扰电厂灰场的一大问题。通过对石家庄井陉某大型火力发电厂灰场(灰渣体积31×10~4m^3)的地下水资料收集、现场调查、水质检测、数据分析预测,对井陉地区水文地质条件进行模型概化,用数值模拟的方法预测灰场特征污染物氟化物和六价铬的污染运移情况,探讨分析了灰场污染物泄漏进入地下水环境的迁移范围和影响程度,认为该灰场地下水对周边环境影响很小,从而对灰场的地下水生态环境保护提供指导作用。     

浦东新区建设与地下空间开发相结合的探讨

本文通过对上海浦东区主要灾情的分析和防灾设施上存在的主要问题论述了浦东新区建设,实行防灾、防冬与地下空间三结合的必要性和从城市总体布局、结合城市交通发展、通过合理安排城市生命线工程以及结合民用建筑的修建进行三结合的可能性.同时,提出了浦东新区建设实行三结合必须加强的几项工作.     

Comprehensive concept planning of urban greening based on ecological principles: a case study in Beijing, China

Greenspace is an important part of complex urban ecosystems and provides significant ecosystem services. It benefits urban communities environmentally, esthetically, recreationally and economically. Beijing Province is in north of China, and has a total area of 16,807.8 km² and a population of about 13.8 million. This paper aims to develop a comprehensive conceptual framework for urban greening of Beijing Province based on landscape ecological principles. It attempts to answer how to establish an urban greening plan at the regional, city and neighborhood levels to achieve long-term sustainability. At the regional level, a big natural and semi-natural forest area in the northwest and an ecological buffer belt in the southeast are planned to protect the environmental quality of Beijing and provide habitats for wildlife. At the city level, a green network system of green wedges, parks and green corridors has been proposed. This green network helps to limit future urban expansion, improve urban environmental quality and serve as habitats and migration routes for wildlife. At the neighborhood level, green extensions and connections of riverside greenway, road greenway, parks and vertical greening permeate into the built-up areas. They provide open space close to residential areas and offer places for recreation. This three-level green system constitutes an integrated ecological network for urban sustainable development of Beijing. For future development of Beijing, urban parks, forestry, agriculture, water and infrastructure should be planned and designed in an integrated way. After this greenspace plan is legislated and completely realized, Beijing will develop an interconnected and integrated network of urban greenspaces. It has the prospect of achieving the aim of “Green Olympic City 2008” and the long-term goal of developing Beijing towards an “Eco-City”.     

Lidar observations of the diurnal variations in the depth of urban mixing layer: a case study on the air quality deterioration in Taipei, Taiwan

An aerosol light detection and ranging (LIDAR) system was used to measure the depth of the atmospheric mixing layer over Taipei, Taiwan in the spring of 2005. This paper presents the variations of the mixing height and the mixing ratios of air pollutants during an episode of air quality deterioration (March 7-10, 2005), when Taipei was under an anti-cyclonic outflow of a traveling high-pressure system. It was found that, during those days, the urban mixing height reached its daily maximum of 1.0-1.5 km around noon and declined to 0.3-0.5 km around 18:00 (LST). In terms of hourly averages, the mixing height increased with the ambient temperature linearly by a slope of 166 m/degrees C in daytime. The consistency between the changes in the mixing height and in the ambient temperature implied that the mixing layer dynamics were dominated by solar thermal forcing. As the cap of the mixing layer descended substantially in the afternoon, reduced dispersion in the shallow mixing layer caused the concentrations of primary air pollutants to increase sharply. Consequently, the pollutant concentration exhibited an anti-correlation with the mixing height. While attentions are usually focused on the pollution problems occurring in a morning inversion layer, the results of this study indicate that the air pollution and its health impacts could be even more severe as the mixing layer is getting shallow in the afternoon.     

A fieldwork study on the diurnal changes of urban microclimate in four types of ground cover and urban heat island of Nanjing,China

Records of the past years showed that the climate of built-up regions differs significantly from rural regions and one of the most obvious and important modifying effects of urbanization on local climate is the urban heat island (UHI). In this paper, four types of land cover, namely urban bare concrete cover, urban woods or the shade of trees, urban water areas and urban lawn, were selected to study their microclimate, and the UHI was also analyzed using air temperature data measured at four fixed observation spots in Nanjing, China, during hot weather from July to September, 2005. Dry and wet bulb temperature data were obtained by whirling psychrometers, and wind speed data by cup anemometers. Our observed data focused on the detailed statistical analysis of the microclimate variation in the four types of land cover during the whole day. The results showed that: (1) the microclimate of these four types of land cover had significant differences among different observation sites. In general, the air temperature of these four types of land cover complied with the order during daytime: bare concrete cover>lawn>water areas>woods or the shade of trees, with reversed order during nighttime when the air temperature of the lawn became the lowest. Compared with the bare concrete cover, the other three types of land cover showed the effect of dropping air temperature ranging between 0.2 and 2.9 °C. There were some instant dynamic characteristics in detailed temporal series among these four types of cover in the different observation sites. (2) The UHI effect could be detected obviously by the air temperature difference between the urban center area and the rural area. The average UHI intensity during the monitoring period was between 0.5 and 3.5 °C; however, there were also significant day-to-day variations. A strong UHI effect usually occurred around midnight; while about 2–3 h after sunrise the UHI began to decrease till midday time; and during 13:00–15:00, the UHI effect had a sudden increase and then decreased again; after sunset, a peak UHI effect was frequently observed during 18:00–21:00. (3) Finally, by means of the standard deviation (SD), this paper provides a concise and comprehensive understanding for the temporal and spatial microclimatic dynamics of these four kinds of urban cover in the four observation sites. Air temperature at the height of 1.5 m in Nanjing showed that the nocturnally horizontal temperature gradient was somewhat different from that reported in other large cities, and a marked heterogeneity in a smaller ground cover scale could be detected from the microclimatic spatial pattern. There is no doubt that the analysis of these four types of land cover presents the insight into possible countermeasures to decrease the high air temperature in hot summers, and is relevant to the urban planning redevelopment.     

Impact of urban upgrading on perceptions of safety in informal settlements: Case study of Bouakal,Batna

This paper explores how modifications of urban space in informal settlements influence residents′ quality of life and perceptions of safety. This is a case study of Bouakal, the oldest informal district in Batna, a middle city in Algeria. This paper examines the effects of urban improvement practices in Bouakal by exploring two questions: In what ways did interventions in this informal settlement affect the quality of life for the residents? How do these effects correlate with changes in the perception of safety in this area? The survey involved 141 residents from Bouakal, and local residents were selected to collect the levels of perceived safety. This paper concludes that urban upgrading has improved the quality of life and has a positive effect on the perception of safety in the settlement.     

Impact of urban geometry on outdoor thermal comfort and air quality from field measurements in Curitiba,Brazil

Urban climate can have severe impacts on people who use outdoor spaces within a city. In its essence, urban climate is directly linked to the configuration of street axes, building heights and their attributes. Thus, the role of urban planners can be crucial for guaranteeing outdoor thermal comfort and air quality in open spaces. This paper presents observed and estimated relations between urban morphology and changes in microclimate and air quality within a city center. Two approaches are presented, showing results of field measurements and urban climate simulations using the ENVI-met software suite. From measured microclimatic data and comfort surveys, carried out in downtown Curitiba, Brazil, the impact of street geometry on ambient temperatures and on daytime pedestrian comfort levels was evaluated, using the sky-view factor (SVF) as indicator of the complexity of the urban geometry. The impact of street orientation relative to prevailing winds and the resulting effects of ventilation (air speed and spatial distribution) on the dispersion of traffic-generated air pollutants were additionally analyzed by means of computer simulations. Results show the impact of urban geometry on human thermal comfort in pedestrian streets and on the outcomes of pollutant dispersion scenarios.     

The Riverside and Berwyn experience: Contrasts in landscape structure, perceptions of the urban landscape, and their effects on people

Humans not only structure the landscape through their activities, but their perceptions of nature are affected by the spatial and temporal arrangements (structure) in the landscape. Our understanding of these interactions, however, is limited. We explored the relationship between landscape structure and peoples’ perceptions of nature in the Chicago, IL, USA, suburbs of Riverside and Berwyn because they offer contrasting paradigms of an urban landscape. Designed in the 1800s by Frederick Law Olmsted, Riverside has several unique design elements (curvilinear streets, ample setbacks, parkways of variable width with mowed grass and naturalistic groupings of trees) that define the structure and composition of this landscape. The urban forest was the keystone of Olmsted's desire to create a harmonious community characterized by “refined sylvan beauty”. In contrast, the adjacent community of Berwyn has right-angled streets with small lots and narrow setbacks for houses. Differences in landscape structure between the two communities produced differences in the diversity, size, and composition of woody vegetation. As measured by patch-size distribution, Riverside had greater diversity in landscape structure than Berwyn, and in turn, Riverside had greater diversity in the composition and size of the woody vegetation compared to Berwyn. Riverside tended toward a “natural” appearance with vegetation, while yards in Berwyn tended to be trimmed and edged. Significant differences between the mean ratings of Riverside and Berwyn respondents were found for six of seven community attribute categories. Riverside participants reported receiving greater benefit from the visual and nature-related features of the urban forest than did Berwyn respondents. Berwyn residents ranked social atmosphere for the community and locomotion (wayfinding) highest among the seven community attribute categories. Despite differences between the two communities, residents valued the green residential environment provided by vegetation. However, the more diverse urban landscape as measured by built structures, woody vegetation, and lot size and shape proved to be more satisfying to the residents of these two communities. The design concepts developed and implemented by Olmsted more than century ago in Riverside are still relevant to city planners striving to develop living environments that are satisfying to urban and suburban residents.     

Influence of traffic force on pollutant dispersion of CO,NO and particle matter (PM2.5) measured in an urban tunnel in Changsha,China

Environmental safety issues and ventilation problems caused by the construction of urban tunnel have increasingly been attracting people’s attention. Previous studies in China have mainly focused on vehicle emissions and ventilation control technologies in road tunnels, resulting in a research gap on urban tunnel ventilation engineering design. Therefore, a detailed monitoring investigation was conducted from May 22 to June 2, 2013 in Changsha Yingpan Road Tunnel, China. The study aim was to measure the traffic characteristics, air velocity and the carbon monoxide (CO), nitrogen oxides (NO_x) and fine particulate matter (PM_2.5) concentrations in this tunnel, which has two lanes per bore and multiple ramps. Measurement results show that during the workday morning peak, the maximum traffic flow was 1560 passenger-car-unit/h per lane with vehicle speed around 33.6 km/h in the eastbound tunnel, the average air velocity was 3.07 m/s, and the proportion of the light-duty vehicles (LDV) was 97.3%. Under the traffic force (not open fan), the CO and NO average concentrations at the main tunnel outlet were 20.3 ppm and 1.65 ppm, respectively. The gas pollutant concentrations are effectively controlled within the multiple-ramps tunnel and the design air volume flow is noticeably reduced. The traffic air flow was found to provide 32.5% of the required air volume to dilute NO_x in blocked traffic condition (vehicle speed of 10 km/h). In addition, the PM_2.5 concentration is mainly affected by the value of background outside the tunnel. The result can provide a quantitative assessment method to support pollutant concentration control and contribution of requested air volume by traffic flow in urban complex structure tunnel.     

Determination of anthropogenic and biogenic compounds on atmospheric aerosol collected in urban, biomass burning and forest areas in São Paulo, Brazil

This study was conducted at three sites of different characteristics in São Paulo State: São Paulo (SPA), Piracicaba (PRB) and Mata Atlântica Forest (MAT). PM₁₀, n-alkanes, pristane and phytane, PAHs, water-soluble ions and biomass burning tracers like levoglucosan and retene, were determined in quartz fiber filters. Samplings occurred on May 8th to August 8th, 2007 at the MAT site; on August 15th to 29th in 2007 and November 10th to 29th in 2008 at the PRB site and, March 13th to April 4th in 2007 and August 7th to 29th in 2008 at the SPA site.Aliphatic compounds emitted biogenically were less abundant at the urban sites than at the forest site, and its distribution showed the influence of tropical vascular plants. Air mass transport from biomass burning regions is likely to impact the sites with specific molecular markers.The concentrations of all species were variable and dependent of seasonal changes. In the most dry and polluted seasons, n-alkane and cation total concentrations were similar between the megacity and the biomass burning site. PAHs and inorganic ion abundances were higher at São Paulo than Piracicaba, yet, the site influenced by biomass burning seems to be the most impacted by the organic anion abundance in the atmosphere. Pristane and phytane confirm the contamination by petroleum residues at urban sites; at the MAT site, biological activity and long range transport of pollutants might influence the levels of pristane.