Urbanization in China from the end of 1980s until 2010 – spatial dynamics and patterns of growth using EO-data

Urbanization in China has been experiencing a remarkable dynamism in the past 40 years.The most evident implication of urbanization is the physical growth of cities.We analyze urban land growth rates and changes in spatial urban forms from the end of the 1980s to 2010 based on the authoritative National Land Use/Cover Database of China.We present new spatial measures that describe‘urban land growth types’and‘fluctuations in urban land growth’within the monitoring time span with a temporal interval of five-year steps.We evaluate the correlations between urban land growth rates and socioeconomic data.Results show that(1)distinct characteristics exist on the spatiotemporal evolutions of urban land growth rates in terms of area and perimeter,e.g.coastal areas exhibit the most dramatic growth rates;(2)the spatial distribution characteristics of‘urban land growth types’and‘fluctuations in urban land growth’follow similar spatial patterns across China,e.g.significant differences exist between the eastern region and other regions;and(3)a moderate correlation exists between urban area growth rate and urban population growth rate at an R2 of 0.37.By contrast,we determine no significant correlation between urban area growth rate and tertiary industry value growth rate.

Urban spatial structure analysis:quantitative identification of urban social functions using building footprints

Analysis of urban spatial structures is an effective way to explain and solve increasingly serious urban problems.However,many of the existing methods are limited because of data quality and availability,and usually yield inaccurate results due to the unclear description of urban social functions.In this paper,we present an investigation on urban social function based spatial structure analysis using building footprint data.An improved turning function(TF)algorithm and a selforganizing clustering method are presented to generate the variable area units(VAUs)of high-homogeneity from building footprints as the basic research units.Based on the generated VAUs,five spatial metrics are then developed for measuring the morphological characteristics and the spatial distribution patterns of buildings in an urban block.Within these spatial metrics,three models are formulated for calculating the social function likelihoods of each urban block to describe mixed social functions in an urban block,quantitatively.Consequently,the urban structures can be clearly observed by an analysis of the spatial distribution patterns,the development trends,and the hierarchy of different social functions.The results of a case study conducted for Munich validate the effectiveness of the proposed method.

Scenario Prediction and Analysis of Urban Growth Using SLEUTH Model

Scenario prediction was introduced to better understand urban dynamics and to support urban planning. Taking the Dongguan central urban area of the Pearl River Delta, China as an example, three urban development scenarios, historical trend (HT) scenario, forest protection (FP) scenario, and growth restriction (GR) scenario, were designed and transplanted into the SLEUTH model through the parameter self-modification method. The quantitative analysis results showed that the urban area would expand continuously from 2003 to 2030 under the HT scenario. More land resources would be saved under the GR scenario than FP scenario. Furthermore, the urban growth under the HT and FP scenarios would come to a steady state by 2020, while this deadline of the GR scenario would be postponed to 2025. The spatial pattern analysis using five spatial metrics, class area, number of patches, largest patch index, edge density, and contagion index, showed that under all the scenarios, the urban patches would become bigger and the form would become more compact, and the urban form under the GR scenario would be the smallest and most heterogeneous. These demonstrated that the GR scenario was more effective in meeting the goal of land protection and sustainable development for the study area.

Assessment of Urban Climate Environment and Configuration of Ventilation Corridor:A Refined Study in Xi'an

Integrating urban spatial landscape(USL) parameters into refined climate environment assessment is important. By taking the central urban area(CUA) of Xi’an, China as an example, this study develops an evaluation method based on Urban Climatic Map(UCMap) technology. We define surface urban heat island intensity(SUHI) and surface ventilation potential coefficient(VPC), which can effectively reflect local urban climate. Based on SUHI and VPC,we analyze the influences of seven typical USL metrics including building height(BH), building density(BD), floor area ratio(FAR), sky view factor(SVF), frontal area index(FAI), surface roughness length(RL), and vegetation cover(VC). Then, we construct a comprehensive evaluation model and create an urban climate zoning map on a 100-m resolution. The climate optimization on the map is performed for configuration of possible ventilation corridors and identification of associated control indicators. The results show that the main factors affecting SUHI in the CUA of Xi’an are VC and BD, which explain 87.9% of the variation in SUHI, while VPC explains 50% of the variation in SUHI. The main factors affecting VPC are BH, FAR, FAI, and RL, all of which contribute to more than 95% of the variation in VPC. The evaluation model constructed by SUHI, VPC, and VC can divide the CUA into climate resource spaces, climate preservation spaces, climate sensitive spaces, and climate restoration spaces. On this basis, a ventilation corridor network of 3 level-1 corridors(each over 500 m wide), 6 level-2 corridors(each over 500 m wide) and 13 level-3 corridors(each over 50 m wide) is established. Meanwhile, the main quantitative control indicators selected from the USL metrics are proved to be capable of ensuring smooth implementation of the planned corridors at different levels.