Urban detection, delimitation and morphology: comparative analysis of selective "megacities"

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Urban Sprawl and Warming: Research on the Evolution of the Urban Sprawl of Chinese Municipalities and its Relationship with Climate Warming in the Past Three Decades

China is experiencing the largest and fastest urbanization process in the world (Kneebone E., 2013). At the same time, its current rapid urbanization process is almost simultaneously accompanied by urban sprawl. Since the 1990s, the sprawl process of Chinese cities has begun to reach a climax (Shan Baoguo, 2018). As the largest developing country in the world, China is also one of the countries most vulnerable to the coercion of climate change. This research takes the four municipalities that are China's urban development orientation as typical representatives, and uses multiple indicators to measure urban sprawl and climate change in them. Finally, models are established to explore the impact of urban sprawl on climate warming. The results showed that all four cities experienced sprawl, but to varying degrees. Shanghai is very compact. Also, the climate warming is definitely, yet urban sprawl doesn't always contribute to its deterioration. The proportion of arable land had the least impact on global warming, but it was the only factor that could improve temperatures, albeit conditionally. Fragmented built-up land heating the climate is most critical.Peer ReviewedPostprint (published version

The urbanization impact in China: A prospective model (1992-2025)

The gradual spread of urbanization, the phenomenon known under the term urban sprawl, has become one of the paradigms that have characterized the urban development since the second half of the twentieth century and early twenty-first century. The arrival of electrification to nearly every corner of the planet is certainly the first and more meaningful indicator of artificialization of land. In this sense, the paper proposes a new methodology designed to identify the highly impacted landscapes in China based on the analysis of the satellite image of nighttime lights. The night-lights have been used widespread in scientific contributions, from building human development indices, identifying megalopolis or analyzing the phenomenon of urbanization and sprawl, but generally they have not been used to forecast the urbanization in the near future. This paper proposes to study the urbanization impact in China between 1992 and 2013, and models a hypothesis of future scenarios of urbanization (2013-2025). For this purpose, the paper uses DMSP-OLS Nighttime Lights (1992 – 2013). After obtaining a homogeneous series for the whole period 1992- 2013, we proceed to model the spatial dynamics of past urbanization process using thePeer ReviewedPostprint (published version

Les megaestrucutres urbanes del segle XXI: un assaig per la identificació i caracterització de les megalòpolis

El proceso de metropolitanización ha marcado el desarrollo urbano del siglo XX. Sin embargo, especialmente desde 1950, se ha venido produciendo un verdadero cambio de escala en dicho crecimiento: el crecimiento infinito de las periferias metropolitanas, alentado por el proceso de urban sprawl, la urbanización creciente de los entornos rurales en los intersticios existentes entre las ciudades, no sólo ha venido a enlazar espacialmente sistemas urbanos anteriormente aislados, sino que ha generado nuevos espacios urbanos caracterizados por una creciente complejidad, así como por la expansión ilimitada del fenómeno urbanizador. Las megalópolis, intuidas a principios del siglo XX por los pensadores precursores del urbanismo contemporáneo, se han hecho realidad. El objetivo de este trabajo consiste en realizar un ensayo para la identificación y caracterización preliminar de las megalópolis en los inicios del siglo XXI. La publicación reciente por la NASA de la imagen planetaria de las luces nocturnas da la oportunidad para proceder al desarrollo de metodologías de análisis de imagen susceptibles de identificar las mega-estructuras urbanas a escala planetaria.Metropolitanization process has marked the twentieth century urban development. However, since 1950, there has been a real change of scale in this growth: the endless growth of metropolitan suburbs encouraged by the urban sprawl and the increasing urbanization of rural environments in the interstices between cities. This has not only linked previously isolated urban systems, but has generated new urban spaces characterized by increasing complexity, as well as by the unlimited expansion of urbanizing phenomenon. The Megalopolis, intuited in the early twentieth century by the precursor thinkers of contemporary urbanism, have come true. The objective of the paper is to set up a methodology for the identification and preliminary characterization of megalopolis in the early twenty-first century. The recent publication of new global view of Earth's city lights by NASA gives the opportunity to develop methodologies of image analysis capable of identifying urban mega-structures on a planetary scale.El procés de metropolitanització ha marcat el desenvolupament del segle XX. No obstant, especialment des de 1950, s'ha produït un veritable canvi d'escala d'aquest creixement: el creixement infinit de les perifèries metropolitanes, animat pel procés d'urban sprawl, la urbanització creixent dels entorns rurals en els espais existents entre les ciutats, no només ha suposat enllaçar espacialment sistemes urbans anteriorment aïllats, sinó que ha generat nous espais urbans caracteritzats per una creixent complexitat, així com per l'expansió ilimitada de fenomen urbanitzador. Les megalòpolis, intuïdes a principis del segle XX pels pensadors precursors de l'urbanisme contemporani, s'han fet realitat. L'objectiu d'aquest treball consisteix en realitzar un assaig per la identificació i caracterització preliminar de les megalòpolis als inicis del segle XXI. La publicació recent de la NASA de la imatge planetària de llums nocturnes dóna l'oportunitat per procedir al desenvolupament de metodologies d'anàlisi d'imatge susceptible d'identificar les megaestructures urbanes a escala planetària.Peer Reviewe

The urban sprawl: a planetary growth process?: an overview of USA, Mexico and Spain

It is a fact that the urban sprawl, known as the process of gradual spread out of urbanization has become a worldwide phenomenon. The growing consumption of land, as a result of the extension of highway networks, open up vast space of territory, which seems to have become an unstoppable cancer, and affects virtually all the contemporary metropolis. The expansion of the cities had its origin in the model of suburban life, which began with the generalized use of the automobile. A lifestyle based on the "american dream‖, one single family-home, one (or more) car (s)." But it has been since late 70’s of the last century, when it has had a more dramatic development, as a consequence of the crisis of metropolitan areas linked to what, it is called Post-Fordism economy and some authors have characterized as counter-urbanization (Berry) desurbanization (Berg), edge-cities (Garreau) metapolis (Asher) or diffuse city (Indovina). Despite the diversity of urban development, the increasing consumption of land, the excessive use of land as a scarce resource, it is a constant in the urbanization process in the early twenty-first century. The object of our contribution is to make an overwiew about urban sprawl in USA, Mexico and Spain. The use of technologies related to satellite imagery (remote sensing) allow the characterization of the phenomenon of consumption, pathological or not, of land. And this analysis suggests some hypothesis about the plurality of the contemporary urbanization processes. Roughly two models stand out: On one hand, urban development based on low densities, where the unsustainable consumption of land is presented as a paradigm of economic development and, on the other hand, an urban development with a compact city model, where recycling land, and not just increasing the consumption of land, is one of the key objectives of urban policies. The work presented here, suggests that in the second model seems to appear a change in the paradigm towards a more efficient and sustainable use of the territory.Peer Reviewe

Identifying urban heat island: the Barcelona case

There is a large consensus that cities have a special role in the process of climate change. Cities are responsible for 75% of global energy consumption and 80% of GHG emissions, both due to "lifestyle" generated in the last 150 years and changes associated with urbanization process in the era of globalization and urban sprawl. The specialized literature has devoted many efforts to analyze the contribution of urban systems to climate change, occupying the Urban Heat Island (UHI) an important place in studies on urban climate. In this sense, the use of remote sensing technology has allowed detailed mapping of (daytime) land surface temperature (LST) for urban and metropolitan systems. These studies have demonstrated the key role played by vegetation, impervious soil and land uses to explain differences in the spatial distribution of LST. However, the information provided by satellites has important limitations: especially the low resolution of the thermal band of night images. MODIS, for example, provides valuable information on the night LST; however, the spatial resolution of the thermal band is about one km², scale clearly insufficient to identify accurately the spatial structure of the UHI. In the opposite site, Landsat offers a more accepTabla spatial resolution (30 m² / pixel for the visible bands of the electromagnetic spectrum as well as 60 to 100 m² / pixel in the thermal bands), but does not provide information about night soil temperature. In addition, it is at night when the urban heat island becomes more evident. Therefore, to determine the night LST in an appropriate scale (as offered by Landsat) remains a significant challenge in studies aimed at identifying the spatial structure of the UHI. In Metropolitan Area of Barcelona (AMB, 3,200 km² and 4.8 million inhabitants), the (day) highest temperatures are not in the CBD but in areas that are more peripheral specialized in economic activity such as industrial parks, producing a "donut" in the spatial distribution of the LST. Bare soil also shows a (day) high surface temperature. In contrast, sprawled areas have a less pronounced LST. The spatial structure of the LST, however, changed significantly during the night: compact and sprawl areas maintain high levels of heat, facing the agricultural soil, which cools more sharply as also happens in the industrial land. UHI appears therefore overnight. This paper aims to show the spatial patterns of Urban Heat Island in the Metropolitan Area of Barcelona at medium scale (30 m² / pixel). It develops a new methodology aimed at modeling the night temperature at one km² resolution (MODIS) and then extrapolating this methodology to a most accurate scale of 30 m² / pixel (Landsat). The study allows identifying differences in (night) LST according to the distribution of land use, quantity and quality of the vegetation, intensity of urban sprawl, spatial distribution of economic activity and type of urban morphology (continuous vs. scattered urbanization)

Algunas reflexiones sobre el proceso de sprawl en España y México

El objeto de nuestra contribución es realizar algunas reflexiones acerca del proceso de sprawl en España y México. El desarrollo de las tecnologías vinculadas a la imagen satelital (remote sensing) permiten la caracterización del fenómeno de consumo, patológico o no, de suelo. Y de ese análisis surgen hipótesis acerca de la pluralidad de los procesos de urbanización contemporáneos. A grandes rasgos sobresalen dos grandes modelos: por una parte los desarrollos urbanos basados en bajas densidades, en el que el consumo insostenible de suelo se presenta como paradigma del desarrollo económico. Por otra los desarrollos que apuestan por modelos más compactos de urbanización, en los que el reciclaje, y no sólo el consumo creciente de suelo, se presenta como uno de los objetivos centrales de la política urbana. El trabajo que aquí se presenta sugiere que en estos últimos años parece apuntarse un cambio de paradigma hacia un sistema más eficiente y sustentable de utilización del territorio.*** ENG: This paper pretends to make some reflections about the urban sprawl process in the metropolitan areas in Spain and Mexico. The use of technologies related to satellite imagery (remote sensing) allows the characterization of the phenomenon of consumption, pathological or not, of land. And this analysissuggests some hypothesis about the plurality of contemporary of urbanization processes. Roughly two models stand out: one based urban development at low densities, where the unsustainable consumption of land is presented as a paradigm of economic development and, another hand, an urban development with a compact city model, where recycling land, and not just increasing the consumption of land, is one of the key objectives of urban policy. The work presented here, suggests that in recent years appears a change in the paradigm towards a more efficient and sustainable use of the territory.Peer Reviewe

Can urban design mitigate the UHI effect?

The Land Surface Temperature (LST) plays a key role in the generation of the Urban Heat Island (UHI), representing a determining factor of the radiation of the surface and the exchange of energy and control the distribution of heat between the surface and the atmosphere. The composition of the land covers is one of the main factors that influence the LST. The literature have highlighted that the different types of land cover materials, their albedo and roughness, degree of impervious as well as the quality and quantity of vegetation, can have a significant impact on the generation of the UHI. The overall objective of the paper is to investigate if urban design, on a detail scale, can mitigate the Urban Heat Island. The question is if the morphology of public space, especially the form and zoning of green areas and open spaces, influence surface (LST) and air (LSAT) temperatures and therefore in the UHI. The working hypothesis is that the morphology of public space plays a key role to control UHI. Thus, an adequate design of open spaces can help to increase the resilience of cities to Climate Change (CC). To prove the hypothesis, two case studies were chosen. The case studies are two urban expansion areas of city of Sant Cugat del Vallès (in the metropolitan area of Barcelona), the first one, called Parc Central and the second one, Coll Favà. Both have similar characteristics, but with a clearly differentiated public space design; while in Parc Central built-up area is structured around the open space, in Coll Favà, the vast majority of open spaces are located peripherally, surrounding the built-up areas. The research methodology consisted in: a) studying the urban and climatic parameters of selected areas; b) analyzing the spatial distribution of the LST using remote sensing technologies (Landsat 8); c) obtaining LST and LSAT through field work, during day and night time; and d) constructing a model of surface and air temperatures as a function of the different types of land cover, combining Remote Sensed data and in situ measurements, for each of the areas of analysis.Peer ReviewedPostprint (author's final draft

Plusvalías y regeneración urbana: el caso de estudio del Centro Histórico de Guadalajara

A windfall is any increase in the value of real estate, other than that caused by the owner or by general inflation, more particularly, is any increase in the value of land arising from a planning decision. The specialized literature (Hagman & Misczynsk, 1978) has discussed if windfalls can be recaptured, offering ways to get it, such as land value taxes, taxes on gains in property value, special assessments, zoning and so on. The purpose of this paper is to analyse different strategies for returning to the community the windfalls resulting from changes in urban planning at the historic downtown of Guadalajara, Mexico. The methodology consists in a review of the existing databases, laws and changes in urban plans and to elaborate a 3D Model and a Geographic Information System to represent and identify the "Urban Potential" derived from urban planning and makes an approach of how the land windfalls can be another way of municipal revenue through several proposals of value capture instruments. As a result, the study proposes the exploitation of this potential and estimates the land windfalls for the study area. The change in the land use from single family home to multi-family buildings, and the restructuring of services and shops into office buildings and creative activities, as well as the densification of the area is the aim of this urban regeneration to make a Sustainable and Holistic Urban Development. The research is original and outstanding because there is no tradition in Mexico to use the value capture from urban planning as municipal revenue. Until now, the city government uses only the value capture from public works as special assessments. The study was prepared at the request of the municipality of Guadalajara through the City Planning Commission.Peer Reviewe

Urban Sprawl en Europa: las periferias de las metrópolis, principal escenario de la dispersión de la urbanización

El discurso político territorial europeo ha denunciado el creciente consumo de suelo artificializado que generan los actuales procesos de dispersión urbana. La demanda creciente de suelo, por encima del crecimiento demográfico y económico, ha devenido uno de los paradigmas del "desarrollo" territorial del "primer mundo". Así, el consumo de suelo por habitante alcanzaba en las aglomeraciones de más de 500.000 habitantes, hacia principios de la década pasada, unos 350 m2 de suelo por habitante tanto en Europa como en el mundo más desarrollado, frente a tan sólo unos 125 m2 en el resto del planeta. La tendencia progresiva hacia el consumo masivo de suelo es especialmente preocupante en las grandes metrópolis, allá donde la presión de la urbanización alcanza niveles más acusados: por poner un solo ejemplo, mientras un 4,7% del territorio europeo se encontraba urbanizado en el año 2000, esa proporción alcanzaba un 15,6% en los entornos de las principales regiones urbanas europeas. La presente ponencia busca evaluar el grado de urban sprawl así como contrastar las características de los diferentes modelos de ocupación de suelo en las principales áreas metropolitanas europeas. En este contexto, el trabajo que aquí se presenta parte de la hipótesis de que es en las periferias metropolitanas europeas donde las patologías del sprawl se hacen más acusadas. A tal efecto se desarrollan metodologías innovadoras, basadas en criterios multidimensionales, dirigidas a la delimitación no sólo de los propios "artefactos" a analizar (las grandes metrópolis europeas), sino también a diferenciar sus centros y periferiasPeer Reviewe