Decades of urban growth and development on the Asian megadeltas

The current and ongoing expansion of urban areas worldwide represents the largest mass migration in human history. It is well known that the world's coastal zones are associated with large and growing concentrations of population, urban development and economic activity. Among coastal environments, deltas have long been recognized for both benefits and hazards. This is particularly true on the Asian megadeltas, where the majority of the world's deltaic populations reside. Current trends in urban migration, combined with demographic momentum suggest that the already large populations on the Asian megadeltas will continue to grow. In this study, we combine recently released gridded population density (circa 2010) with a newly developed night light change product (1992 to 2012) and a digital elevation model to quantify the spatial distribution of population and development on the nine Asian megadeltas. Bivariate distributions of population as functions of elevation and coastal proximity quantify potential exposure of deltaic populations to flood and coastal hazards. Comparison of these distributions for the Asian megadeltas show very different patterns of habitation with peak population elevations ranging from 2 to 11 m above sea level over a wide range of coastal proximities. Over all nine megadeltas, over 174 million people reside below a peak population elevation of 7 m. Changes in the spatial extent of anthropogenic night light from 1992 to 2012 show widely varying extents and changes of lighted urban development. All of the deltas except the Indus show the greatest increases in night light brightness occurring at elevations < 10 m. At global and continental scales, growth of settlements of all sizes takes the form of evolving spatial networks of development. Spatial networks of lighted urban development in Asia show power law scaling properties consistent with other continents, but much higher rates of growth. The three largest networks of development in China all occur on deltas and adjacent lowlands, and are growing faster than the rest of the urban network in China. Since 2000, the Huanghe Delta + North China Plain urban network has surpassed the Japanese urban network in size and may soon connect with the Changjiang Delta + Yangtze River urban network to form the largest conurbation in Asia

Towards a sustainable urban expansion: a case study of cities in Bangladesh

The economic growth of Bangladesh over the last several decades has subsequently been followed by the rapid expansion of urban areas. Unfortunately, this expansion of the urban footprint has mostly occurred in an unplanned and chaotic manner through the conversion of natural areas to urban landscape due to the lack of regulation and policies guiding the country’s urban planning. This has raised concerns about the sustainability and livability of these cities and urged the need for a robust planning framework targeted at promoting sustainable urban expansion. A well-x and enhancing the quality of life for everyone while minimizing environmental degradation and other potential adverse impacts of a growing number of city dwellers. This dissertation examines the extent of unevenness in urban growth patterns in Bangladesh and explores the application of Urban Growth Boundaries (UGB) as a mechanism to control and direct the growth of built-up urban areas to promote sustainable urban expansion of these cities. The first part of the dissertation examines the unevenness in the urban expansion in Bangladesh by comparing the urban footprint of the cities and municipalities in Bangladesh extracted using Google Earth Engine (GEE) and census population data for these areas. While a greater proportion of the population has been increasingly concentrated in the smaller and mid-sized cities over the last three decades, built-up urban areas, on the other hand, have been mostly clustered in the two largest cities— Dhaka and Chattogram—accounting for nearly 60 percent of the total built-up urban areas. These results shed light on the magnitude of continued spatial inequalities in urban development amongst cities and municipalities in Bangladesh despite there being an overall increase of evenness in the distribution of population over time. The second part of the dissertation explores the application of UGB delineation using Support Vector Machine (SVM) supervised machine learning algorithm as an urban growth restriction mechanism for the city of Chattogram, one of the world's largest port cities and the second-largest metropolitan areas in Bangladesh, as a case study. The application of the Support Vector Machine (SVM) supervised machine learning algorithm is a novel approach to the delineation of UGB and this model was used to simulate future built-up urban areas up to 2040 for Chattogram and to determine the UGB for the city. Although the delineation of the UGB is a crucial step for the adoption and implementation process of UGB for Chattogram, the overall success of the UGB policy is dependent on external factors that directly or indirectly impact the policy. The third part of the dissertation, thus, investigates the key considerations essential for the successful adoption and implementation of UGB for Chattogram. Through a systematic review of literature on UGB and planning policies on Chattogram, along with a web-based survey and unstructured interview with city officials, it examines the stakeholders’ perceptions on current growth patterns, the potential application of UGB as an urban growth containment strategy, and concerns and support regarding the application of UGB. While there has been an overall positive response regarding a potential adoption of UGB for Chattogram, this paper identifies five key concerns that would need to be addressed for the successful adoption and implementation of UGB for the city of Chattogram. These key challenges are namely: policy and regulatory consideration, civic engagement and stakeholder input, bureaucratic consensus and coordination, institutional capacity, and external influences. While distinct, these concerns are highly interrelated and can be expected to have a substantial influence on one another and need to be addressed for the successful adoption of UGB. These key challenges including policy and regulatory consideration, civic engagement and stakeholder input, bureaucratic consensus and coordination, institutional capacity, and external influences. While parts III and IV of this dissertation specifically focuses on the city of Chattogram as a testbed for the application of UGB, a similar methodological approach could potentially be implemented for other cities in Bangladesh with the goal to promote sustainable urban expansion

El urban sprawl : un modelo de urbanización insostenible

Tesi en modalitat de compendi de publicacions, amb diferents articles retallats per drets de l'editor.(English) he present thesis consists in a PhD thesis by compendium of publications. The general objective of the thesis is the analysis of the phenomenon of the Urban Sprawl, on a planetary scale, starting from the hypothesis that it is an unsustainable process. For the development, specific objectives were set that include the evolution of the research through a selection of 20 papers. The objectives are: a) Analyzing the Urban Sprawl urbanization model, by reviewing the specialized literature; b) Studying the genesis and evolution c) Quantify the Urban Sprawl from databases of local, regional and global, raising the question: is the Sprawl a phenomenon of planetary scope? d) Verify the hypothesis that in Europe, despite having a relatively dense metropolitan structure, there is a pronounced process of Urban Sprawl in the peripheries of large cities e) Define the “city” in the Sprawl era, defining urban and metropolitan systems based on morphological, economic and functional criteria f) Develop a methodology for the analysis of the internal structure of metropolises, capable of contrasting the degree of monocentrism and polycentrism of urban and metropolitan systems and verify the hypothesis that a higher degree of polycentrism reduces the degree of Sprawl (+ Polycentrism =-Sprawl) g) Apply this methodology to the analysis of specific cases, such as the Spanish urban system h) Apply the above methodology to analyze the efficiency in land consumption of the metropolitan systems of Madrid and Barcelona, Los Angeles and Chicago i) Analyze the process of urbanization through the land impacted by urbanization on a global scale, through images of night lights, delimiting metropolitan and megalopolitan areas and defining the different landscapes of human settlements j) Assess suitability of nighttime images to identify urban areas (in relation to rural settlements), and especially the Urban Sprawl, as well as, quantify the retrospective (and prospective) dynamics of the urbanization process (with special attention to China) k) Evaluate the climatic behavior of dispersed and low-density fabrics in comparison to the rest of urban and rural fabrics and uses; l) Study the daytime and nighttime Urban Heat Island (UHI), its spatial distribution and climatic performance of the different types of land covers; m) Study the urban factors that increase the adaptation of cities to global warming, specifically, urban parks as islands of cold in the context of the UHI n) Analyze the effects of heat waves on health, as well as the effect of urban greenery. The thesis, on the one hand, confirms the hypothesis of the unsustainability of the Urban Sprawl, since it implies a high consumption of land, in addition to generating unsustainable mobility. In the same way, it implies a fragmented and dispersed urbanization model, higher energy consumption and promotes social segregation. On the other hand, from the perspective of adaptation to climate change, the Urban Sprawl undoubtedly has a better performance, mainly due to the quality and quantity of green areas present in this type of urban fabric (absent in the central and dense city) and its proximity to those rural or forest areas, which are spaces that produce fresh air. The great challenge of spatial and urban planning is to stop this process of urban expansion without compromising the quality of life, comfort and human health. In this sense, it is necessary to proceed with a radical regeneration of the inherited urban fabrics. The compact city model cannot simply be considered the paradigm of sustainability. It must learn from the green spaces per inhabitant present in the Sprawl. Therefore, it can be concluded that green compactness is the new paradigm of 21st century cities.(Español) La tesis consiste en una tesis por compendio de publicaciones y el objetivo central es el análisis del fenómeno de la dispersión de la urbanización llamado Urban Sprawl a escala planetaria, partiendo de la hipótesis de que se trata de un proceso insostenible. Para el desarrollo de la misma se plantearon objetivos específicos que han sido desarrollados a través de artículos. Estos objetivos son: a) analizar el modelo del Urban Sprawl, mediante la revisión de la literatura especializada b) estudiar su génesis y evolución c) cuantificar el Urban Sprawl a partir de bases de datos de alcance local, regional y mundial, planteando la interrogante ¿es el Sprawl un fenómeno de alcance planetario? d) verificar la hipótesis de que en Europa, a pesar de tener una estructura metropolitana relativamente densa, existe un acusado proceso de Urban Sprawl en las periferias de las grandes ciudades e) delimitar la “ciudad” en la era del Sprawl, definiendo los sistemas urbanos y metropolitanos a partir de criterios morfológicos, económicos y funcionales f) desarrollar una metodología para el análisis de la estructura interna de las metrópolis, capaz de contrastar el grado de monocentrismo y policentrismo de los sistemas urbanos y metropolitanos y verificar la hipótesis de que un mayor grado de policentrismo atenúa el grado de Sprawl (+ Policentrismo = - Sprawl) g) aplicar dicha metodología al análisis de casos concretos, como es el sistema urbano español h) aplicar la anterior metodología para analizar la eficiencia en el consumo de suelo de los sistemas metropolitanos de Madrid y Barcelona, Los Ángeles y Chicago i) Analizar el proceso de urbanización a través del suelo impactado por la urbanización a escala mundial, por medio de imágenes de luces nocturnas, delimitando áreas metropolitanas y megalopolitanas a escala mundial y definiendo en las mismas los diferentes paisajes de los asentamientos humanos j) evaluar la capacidad de las luces nocturnas para identificar las áreas urbanas y muy especialmente el Urban Sprawl, así como cuantificar la dinámica retrospectiva (y prospectiva) del proceso de urbanización (con especial atención a China); k) evaluar el comportamiento climático de los tejidos dispersos y de baja densidad en comparación al resto de tejidos y usos urbanos y rurales; l) Estudiar la Isla de Calor Urbana (UHI) diurna y nocturna, su distribución espacial y comportamiento climático de los diferentes tipos de cubiertas de suelo; m) estudiar los factores urbanísticos que incrementan la adaptación de las ciudades al calentamiento global, específicamente, los parques urbanos como islas de frío en el contexto de la UHI; y n) analizar los efectos que tienen las olas de calor en la salud, así como el efecto del verde urbano. La tesis, por un lado, confirma la hipótesis de la insostenibilidad del Urban Sprawl, dado que implica un alto consumo de suelo, además de generar una movilidad insostenible. Del mismo modo, implica un modelo de urbanización fragmentado y disperso, un mayor consumo energético y promueve la segregación social. Por otro lado, desde la perspectiva de la adaptación al cambio climático, el Urban Sprawl tiene sin duda un mejor comportamiento, principalmente por la calidad y cantidad de espacio verde presente en este tipo de tejido urbano (ausente en la ciudad central y densa) y su proximidad a aquellas zonas rurales o forestales, que son espacios que producen aire fresco. El gran desafío de la planificación territorial y urbana es detener este proceso de expansión urbana sin comprometer la calidad de vida, el confort y la salud humana. En este sentido, es necesario proceder a una reforma radical de los tejidos urbanos heredados. El modelo de ciudad compacta no puede ser considerado simplemente el paradigma de la sostenibilidad. Debe aprender de la mayor cantidad de espacios verdes por habitante presente en el Sprawl. Por tanto, concluir que la compacidad verde es el nuevo paradigma de las ciudades del siglo XXI.Postprint (published version

Fire Type Classification in the Brazilian Tropical Moist Forest Biome

The Brazilian Tropical Moist Forest Biome (BTMFB) is “Earth’s greatest biological treasure and a major component of the earth system” and forest degradation and deforestation by fire is a serious issue in this region. Fires in the BTMFB can be broadly classified as maintenance, deforestation and forest fire types. Spatially and temporally explicit information on the incidences of fire types are important as they have widely varying atmospheric emissions and ecological impacts. Satellite based remote sensing is a practical means of monitoring the BTMFB that spans almost 4 million km2. However, there has been no way to reliably classify satellite active fire type to date. In this work, methods to characterize MODIS active fire detections are developed using physically based and geographic context/proximity approaches. The research methodology is developed by addressing four hypotheses concerning differences among active fire type characteristics including factors that drive and mediate fire in the BTMFB. Differences in the active fire characteristics among different fire types are presented and discussed. The spatio-temporal distribution of fire types over 8 year (2003-2010) period is documented, analyzed and presented. This dissertation has, to date, resulted in one published, one in press, and one submitted paper