urban dispersion
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2021 ◽  
Author(s):  
Angelo Leogrande ◽  
Alberto Costantiello ◽  
Laureti Lucio ◽  
Domenico Leogrande

Abstract We estimate the Landscape and Cultural Heritage among Italian regions in the period 2004-2019 using data from ISTAT-BES. We use Panel Data with Fixed Effects, Panel Data with Random Effects, Pooled OLS, WLS, Dynamic Panel. We found that the Landscape and Cultural Heritage is negatively associated with “Dissatisfaction with the landscape of the place of life”, “Illegal building”, “Density and relevance of the museum heritage”, “Internal material consumption”, “Erosion of the rural space due to abandonment”, “Availability of urban green”, and positively associated with “Pressure from mining activities”, “Erosion of the rural space by urban dispersion”, “Concern about the deterioration of the landscape”, “Diffusion of agritourism farms”, “Current expenditure of the Municipalities for culture”. Secondly, we have realized a cluster analysis with the k-Means algorithm optimized with the Silhouette Coefficient and we found two clusters in the sense of “Concern about the deterioration of the landscape”. Finally, we use eight different machine learning algorithms to predict the level of “Concern about the deterioration of the landscape” and we found that the Tree Ensemble Regression is the best predictor.


2021 ◽  
Author(s):  
Michael Weger ◽  
Bernd Heinold ◽  
Alfred Wiedensohler ◽  
Maik Merkel

Abstract. There is a gap between the need for city-wide air-quality simulations considering the intra-urban variability and mircoscale dispersion features and the computational capacities that conventional urban microscale models require. This gap can be bridged by targeting model applications on the gray zone situated between the mesoscale and large-eddy scale. The urban dispersion model CAIRDIO is a new contribution to the class of computational-fluid dynamics models operating in this scale range. It uses a diffuse-obstacle boundary method to represent buildings as physical obstacles at gray-zone resolutions in the order of tens of meters. The main objective of this approach is to find an acceptable compromise between computationally inexpensive grid sizes for spatially comprehensive applications and the required accuracy in the description of building and boundary-layer effects. For this purpose, CAIRDIO is applied in dispersion simulation of black carbon and particulate matter for an entire mid-size city using an uniform horizontal resolution of 40 m in this paper. For evaluation, the simulation results are compared with measurements from 5 operational air monitoring stations, which are representative for the urban background and high-traffic roads, respectively. Moreover, the comparison includes the mesoscale host simulation, which provides the boundary conditions. The temporal variability of the concentration measurements at the background sites was largely influenced only by the characteristics of the mixing layer. As a consequence, the model results were not significantly dependent on spatial resolution, so that the mesoscale simulation also performed reasonably well. At the traffic sites, however, concentrations were in addition markedly influenced by the proximity to road-traffic sources and the surrounding building environment. Here, the mesoscale simulation indiscriminately reproduced almost the same urban-background profiles, which resulted in a large positive model bias. On the other hand, the CAIRDIO simulation was able to respond to the significantly amplified diurnal variability with its pronounced rush-hour peaks. This resulted in a consistent improvement of the model deviation to mea- surements compared to the mesoscale simulation. Nevertheless, discrepancies to measurements remain in the 40 m-CAIRDIO simulation, e.g., an underestimation of peak concentrations at two traffic sites inside narrow street canyons. To further research resolution sensitivity, the horizontal grid spacing of locally nested CAIRDIO domains is refined down to 5 m. While for the street canyons the representation of peak concentrations can be improved using horizontal grid spacings of up to 10 m, no further improvements beyond this resolution can be observed. This suggests that the too low peak concentrations with the default grid spacing of 40 m result from an inadequate representation of the traffic emissions inside narrow street canyons. If the total gain in accuracy due to the grid refinements is put in relation to the remaining model error, the improvements are only modest. In conclusion, the proposed gray-scale modeling is a promising downscaling approach for urban air-quality applications. Nevertheless, the results also show that aspects other than the actual resolution of flow patterns and numerical effects can determine the simulations at the urban microscale.


Author(s):  
Carlos F. Amábile-Cuevas ◽  
Daniel Romero-Romero

Aims: Flies are known to spread antibiotic resistant bacteria (ARB), especially from farms to cities; but they may also play a role in the intra-urban dispersion of ARB, in conjunction with poor sanitary conditions. Here, we characterized gram-negative ARB isolated from urban flies (Lucilia and Sarcophaga spp.), and the co-relation with the periodic installation of two open-air markets in Mexico City. Methodology: Forty-two flies were individually captured, and 116 gram-negatives (68 of them Escherichia coli) were isolated from them. Resistance prevalence, and the presence of class 1 integrons was assessed. Results: The isolates were resistant to an average of 2.26 antibiotics (2.6 for E. coli), and 33% of E. coli isolates carried the intI1 gene. Thirteen percent of E. coli isolates produced extended-spectrum beta-lactamases (ESBL), all of them CTX-M, alone or, mostly, along TEM enzymes. Comparing data from market-free days vs. days when open-air markets were installed, the average number of resistance phenotypes per E. coli isolate went from 2.14 to 3.09; the number of resistance phenotypes per fly from 4.62 to 8.88; the average number of resistances per isolate per fly from 1.25 to 2.43; and the ESBL-producing carriage rate per fly from 0.08 to 0.38, respectively (P <.05). Other resistance parameters, were consistently higher among flies captured on market days, but differences were not significant. Conclusion: Urban flies in Mexico City carry a high number of gram-negative ARB; the presence of open-air markets significantly increase the risk of fly-mediated ARB spreading to the neighboring areas.


2020 ◽  
Vol 13 (9) ◽  
pp. 4323-4353
Author(s):  
Paul D. Hamer ◽  
Sam-Erik Walker ◽  
Gabriela Sousa-Santos ◽  
Matthias Vogt ◽  
Dam Vo-Thanh ◽  
...  

Abstract. This paper describes the Eulerian urban dispersion model EPISODE. EPISODE was developed to address a need for an urban air quality model in support of policy, planning, and air quality management in the Nordic, specifically Norwegian, setting. It can be used for the calculation of a variety of airborne pollutant concentrations, but we focus here on the implementation and application of the model for NO2 pollution. EPISODE consists of an Eulerian 3D grid model with embedded sub-grid dispersion models (e.g. a Gaussian plume model) for dispersion of pollution from line (i.e. roads) and point sources (e.g. chimney stacks). It considers the atmospheric processes advection, diffusion, and an NO2 photochemistry represented using the photostationary steady-state approximation for NO2. EPISODE calculates hourly air concentrations representative of the grids and at receptor points. The latter allow EPISODE to estimate concentrations representative of the levels experienced by the population and to estimate their exposure. This methodological framework makes it suitable for simulating NO2 concentrations at fine-scale resolution (<100 m) in Nordic environments. The model can be run in an offline nested mode using output concentrations from a global or regional chemical transport model and forced by meteorology from an external numerical weather prediction model; it also can be driven by meteorological observations. We give a full description of the overall model function and its individual components. We then present a case study for six Norwegian cities whereby we simulate NO2 pollution for the entire year of 2015. The model is evaluated against in situ observations for the entire year and for specific episodes of enhanced pollution during winter. We evaluate the model performance using the FAIRMODE DELTA Tool that utilises traditional statistical metrics, e.g. root mean square error (RMSE), Pearson correlation R, and bias, along with some specialised tests for air quality model evaluation. We find that EPISODE attains the DELTA Tool model quality objective in all of the stations we evaluate against. Further, the other statistical evaluations show adequate model performance but that the model scores greatly improved correlations during winter and autumn compared to the summer. We attribute this to the use of the photostationary steady-state scheme for NO2, which should perform best in the absence of local ozone photochemical production. Oslo does not comply with the NO2 annual limit set in the 2008/50/EC directive (AQD). NO2 pollution episodes with the highest NO2 concentrations, which lead to the occurrence of exceedances of the AQD hourly limit for NO2, occur primarily in the winter and autumn in Oslo, so this strongly supports the use of EPISODE for application to these wintertime events. Overall, we conclude that the model is suitable for an assessment of annual mean NO2 concentrations and also for the study of hourly NO2 concentrations in the Nordic winter and autumn environment. Further, in this work we conclude that it is suitable for a range of policy applications specific to NO2 that include pollution episode analysis, evaluation of seasonal statistics, policy and planning support, and air quality management. Lastly, we identify a series of model developments specifically designed to address the limitations of the current model assumptions. Part 2 of this two-part paper discusses the CityChem extension to EPISODE, which includes a number of implementations such as a more comprehensive photochemical scheme suitable for describing more chemical species and a more diverse range of photochemical environments, as well as a more advanced treatment of the sub-grid dispersion.


Vestnik MGSU ◽  
2020 ◽  
pp. 1239-1248
Author(s):  
Ahad S. Mesrizade

Introduction. Growing urbanization entails the construction of secondary and tertiary highways, buildings, development and protection of the infrastructure, aimed at improving the performance of cities; these actions are closely related to power consumption. The experience has proven that the functional planning of urban areas influences urban transportation. Therefore, the link between urban dispersion and types of transportation has turned into one of arguable points. Uncontrollable and spontaneous urban growth, irrational nation-wide traffic and area planning boost the daily use of cars in the cities. Therefore, the study of the factors that influence suburban sprawl can influence the reduction in the number of urban cars. On the whole, suburban sprawl in Iran increases the distance between home and workplace, shopping malls and entertainment centres, and influences the use of personal vehicles and motorcycles. And it can pollute urban air and generate urban heat islands. Materials and methods. The co-authors have taken advantage of the official statistics, examination findings, geographical maps, draft master plans for cities, integrated transportation plans, plans of engineering and communication infrastructures. Results. Any spontaneous expansion of cities, irrational power consumption cause inefficient use of resources and negative economic and social results. Problems of urban dispersion is a feature of the Anthropocene epoch. Conclusions. The co-authors employed document analysis (printed books, articles, and digital libraries). Rational energy consumption, harmonious urban development and gardening are only feasible if reliance on cars is eliminated. Also, given the development of information and communication technologies, withdrawal of cars from designs and plans of new cities in Iran may be of vital importance for the elimination of economic, social, and numerous other problems.


Atmosphere ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 721 ◽  
Author(s):  
Matteo Bo ◽  
Pietro Salizzoni ◽  
Federica Pognant ◽  
Roberto Mezzalama ◽  
Marina Clerico

The #CHEARIATIRA citizen science campaign was developed in February 2019 in Torino (western part of the Po Valley megacity region). The aim of the campaign was public engagement with measuring NO2 concentrations in an urban area that often exceeds air quality standards. NO2 diffusion tubes were employed by citizens under our supervision. In this paper, we present the main outcomes of a combined approach between the #CHEARIATIRA campaign and the urban dispersion model SIRANE. The results were validated against the available public Air Quality Monitoring Stations (AQMS). The citizens’ passive samplers and the modelled data show a good response in central districts both during the campaign interval and by annual projection. Traffic hotspots and sensitive receptors (schools, hospital) have high concentrations of NO2. Most of the study area (83% of the tubes) is subject to an increased risk of premature death according to epidemiological literature.


Land ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 200
Author(s):  
Rosanna Salvia ◽  
Rares Halbac-Cotoara-Zamfir ◽  
Sirio Cividino ◽  
Luca Salvati ◽  
Giovanni Quaranta

Considering settlement characteristics and population dynamics together over multiple spatio-temporal scales, the present study analyzes the spatial distribution of sparse settlements and population surrounding a large city in Southern Europe (Athens, Greece), in relation with long-term metropolitan growth and recent economic downturns. Results of the analysis identify regional-scale processes of urban compaction during economic expansion (2000s) with incorporation of scattered settlements in a high-density urban fabric, and moderate urban dispersion affecting low-density, peripheral areas in the subsequent period of recession (2010s). However, more heterogeneous dynamics were observed at the local scale. With economic expansion, a slight increase in the number of settlements was observed in local districts experiencing intense sprawl in earlier decades. With recession, a slight decrease in the number of settlements was, in turn, recorded in some rural districts surrounding compact urban centers, likely acting as local hotspots of urban re-densification. Given the multiplicity of socioeconomic factors involved, our findings highlight how urban development follows sequential phases of compaction and dispersion, based on locally differentiated spatial regimes characterizing settlement expansion and population growth. Sustainable urban management should face more actively with increasingly fragmented settlement dynamics at the fringe, prefiguring an appropriate spatial balance between urban centers and sparse settlements in light of recent demographic trends.


2020 ◽  
Vol 12 (10) ◽  
pp. 4097 ◽  
Author(s):  
Ahmed Mustafa ◽  
Jacques Teller

Urban sprawl is widely acknowledged as an environmental and socio-economic challenge worldwide. This study examines urban sprawl in Belgium over six decades from 1950 to 2010. We assume that sprawl is a self-reinforcing process, i.e., sprawl is fueling further sprawl over time. The main objective of this study is to examine this assumption. We measure urban sprawl at four different levels in this study: country, regions, municipalities, and 1-km2 cells. Three sprawl indices are employed: the degree of urban dispersion, degree of urban permeation of the landscape, and built-up land uptake per capita. These three indices consider both the growth of built-up areas and population density to measure the magnitude of sprawl. The drivers of urban sprawl have been analyzed at a 1-km2 level. The examined drivers are previous urban dispersion patterns, distance to urban cores, elevation, and slope degree by means of linear regression. Urban sprawl significantly increased between 1950 and 1980, whereas its increase was more moderate between 1980 and 2010. Urban dispersion and permeation strongly affect the Brussels and Flanders regions. The results show that the increase in the degree of dispersion is locally driven by previous values of dispersion; i.e., it provides an adequate milieu for further dispersion. Therefore, our conclusion is that urban sprawl in Belgium tends to be a self-reinforcing process.


2020 ◽  
pp. 103130
Author(s):  
Alexander L. Brown ◽  
Michael D. Clemenson ◽  
Michael Benson ◽  
Christopher Elkins ◽  
Samuel T. Jones

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