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With the expansion of a city, the urban green space is occupied and the urban heat island effect is serious. Greening the roof surfaces of urban buildings is an effective way to increase the area of urban green space and improve the urban ecological environment. To provide effective data support for urban green space planning, this paper used high-resolution images to (1) obtain accurate building spots on the map of the study area through deep learning assisted manual correction; and (2) establish an evaluation index system of roof greening including the characteristics of the roof itself, the natural environment and the human society environment. The weight values of attributes not related to the roof itself were calculated by Analytic Hierarchy Process (AHP). The suitable green roof locations were evaluated by spatial join, weighted superposition and other spatial analysis methods. Taking the areas within the Chengdu city's third ring road as the study area, the results show that an accurate building pattern obtained by deep learning greatly improves the efficiency of the experiment. The roof surfaces unsuitable for greening can be effectively classified by the method of feature extraction, with an accuracy of 86.58%. The roofs suitable for greening account for 48.08%, among which, the high-suitability roofs, medium-suitability roofs and low-suitability roofs represent 45.32%, 38.95% and 15.73%. The high-suitability green buildings are mainly distributed in the first ring district and the western area outside the first ring district in Chengdu. This paper is useful for solving the current problem of the more saturated high-density urban area and allowing the expansion of the urban ecological environment. [ABSTRACT FROM AUTHOR]

The Yangtze River Economic Belt (YREB), an important industrial belt for food security for China, is facing the challenge of decreasing cultivated land in the process of rapid urbanization. In this case, how to improve the cultivated land use efficiency (CLUE) has become the top priority. Based on data from 108 cities of YREB from 2001 to 2019, we measured CLUE using a slack-based measure with undesirable output (SBM-Undesirable). The high-value area of CLUE shows a trend from multi-core agglomeration to two-core agglomeration, mainly concentrated in Chengdu-Chongqing urban agglomeration and the northern part of the YREB. Then the paper examines the spatial effect of urbanization on CLUE using the Spatial Error Model (SEM). The result shows that population urbanization has significantly promoted the improvement of CLUE in YREB during the sample period. With each percentage point increase in population urbanization, CLUE will increase by 2.99%. Land urbanization has a negative impact on CLUE, for each percent increase in the expansion of urban spatial scope, CLUE will decrease by 0.06%. The spatial heterogeneity analysis shows that population urbanization in the lower reaches has significantly promoted CLUE, with a coefficient of 1.053. The population urbanization level in the middle and lower reaches of the region has no obvious effect on CLUE. The coefficient of land urbanization in the downstream region is 0.35, which significantly promotes CLUE. The coefficient in the middle is −0.26, which implies the CLUE decreases by 0.26% for every one percentage point increase in land urbanization. Land urbanization in the upper has no significant impact on the CLUE. Policy implications include improving the quality of the three major urban clusters along the YREB, building an ecologic protective screen in the upper, encouraging a new agricultural management system and detailed regulations related to the cultivated land protection in YREB. [ABSTRACT FROM AUTHOR]

The development of urbanization has changed the original land cover and exacerbated the urban heat island effect, seriously affecting the sustainable development of the ecological environment. Research on urban heat island characteristics and land cover changes in five major urban agglomerations in China to provide a reference for preventing thermal environmental risks and urban agglomeration construction planning. This paper estimates the surface urban heat island intensity (SUHII) of the five major urban agglomerations in China from 2003 to 2019 based on Google Earth Engine (GEE) through the urban–rural dichotomy, analyzes their trends through the Sen + M–K trend analysis method, and combines the detrending rate matrix to analyze the impact of land cover type shift on urban heat island change. Research shows that (1) the land cover types of the five major urban agglomerations in China have changed considerably from 2003 to 2019, and all five major urban agglomerations in China experienced varying degrees of urban expansion. (2) The annual average value of SUHII decreases in Beijing-Tianjin-Hebei, Yangtze River Delta, and middle reaches of the urban agglomerations, while the annual average value of SUHII increases in Chengdu-Chongqing and Pearl River Delta urban agglomerations. (3) The spatial composition of land cover types in the five major urban agglomerations in China is highly spatially correlated with urban heat islands, with urban land and bare land urban heat islands being the most pronounced. (4) The land cover type shift has the most significant heat island impact on Beijing-Tianjin-Hebei, Yangtze River Delta, and Chengdu-Chongqing urban agglomerations. (5) The land cover change (LCC) with an increasing trend in SUHII is mainly bare land converted to arable land, and water bodies, grassland, forest land, and arable land converted to urban land. [ABSTRACT FROM AUTHOR]

Attaining optimal eco-efficiency is of paramount importance in promoting the sustainable and harmonious development of the economy and environment within urban agglomerations. Firstly, this paper utilizes the Super-SBM model with undesirable output to measure the eco-efficiency (EE) of 64 cities in the Beijing–Tianjin–Hebei metropolitan region (BTHMR), the Yangtze River Delta (YRD), the Pearl River Delta (PRD), and the Chengdu–Chongqing Economic Zone (CCEZ) from 2006 to 2019. Secondly, this study puts forth a novel and comprehensive index system aimed at evaluating the urbanization efficiency and sheds light on the spatiotemporal changes in EE and urbanization efficiency. Finally, the STIRPAT model is used to examine the influencing factors of EE and to investigate the correlation between EE and urbanization efficiency. The study found that the overall EE of the four typical urban agglomerations is high, but the trend varies with a decrease of about 12.9% from 2006 to 2019. The mean EE is in the order of CCEZ > PRD > BTHMR > YRD, with mean values of 0.941, 0.909, 0.842, and 0.732, respectively. The level of science and technology and the urbanization efficiency have a significant positive impact on EE, while population, industrial structure, FDI, and greening level have an inhibitory effect on urban eco-efficiency. Based on the results, policy suggestions such as paying attention to regional heterogeneity and giving full play to the government's macro-regulatory role in shaping the economic and industrial structure are proposed to serve as a guide for the coordinated development of urban agglomerations under the Dual Carbon Target. [ABSTRACT FROM AUTHOR]

The rapid development of megacities has greatly impacted land use in the urban–rural fringe area. The Western Protected Area defined by Chengdu's Master Plan (2016–2035) to end the unrestrained urban sprawl, where locates the most superior agricultural and ecological resources, namely Mount Qingcheng and the Dujiangyan Essence Irrigation District, is facing great challenges when implementing protective strategies, related to huge land use competition caused by land multi-functionality. To better assess and understand land-use conflict and its influence, this paper constructs a comprehensive evaluation model with 'multi-functionality and landscape complexity' based on existing research, with a 1 km × 1 km spatial resolution, and analyzes its relationship with land-use and land-cover (LULC) change, based on 30 m land resolution data from 2000, 2010, and 2020, produced by the Institute of Resource and Environmental Science and the Data Center of the Chinese Academy of Sciences. Overall, two kinds of land-use conflict concerning function suitability and landscape pattern co-emerge spatially, but there also exist "high-low" combinations. The result shows that land consolidation or the adjustment of land use might take place more often when both the suitability conflict and the landscape conflict reach a certain threshold. The results provide enlightenment for further expanding the quantitative research on land-use conflict and confirm the potential of applying the land-use conflict index in delineating territorial spatial planning control areas. [ABSTRACT FROM AUTHOR]

Increases in the area of impervious surfaces have occurred with urbanization. Such surfaces are an important indicator of urban expansion and the natural environment. The automatic extraction of impervious surface data can provide useful information for urban and regional management and planning and can contribute to the realization of the United Nations Sustainable Development Goal 11—Sustainable Cities and Communities. This paper uses Google Earth Engine (GEE) high-resolution remote sensing images and OpenStreetMap (OSM) data for Chengdu, a typical city in China, to establish an impervious surface dataset for deep learning. To improve the extraction accuracy, the Small Attention Hybrid Unet (SAH-Unet) model is proposed. It is based on the Unet architecture but with attention modules and a multi-scale feature fusion mechanism. Finally, depthwise-separable convolutions are used to reduce the number of model parameters. The results show that, compared with other classical semantic segmentation networks, the SAH-Unet network has superior precision and accuracy. The final scores on the test set were as follows: Accuracy = 0.9159, MIOU = 0.8467, F-score = 0.9117, Recall = 0.9199, Precision = 0.9042. This study provides support for urban sustainable development by improving the extraction of impervious surface information from remote sensing images. [ABSTRACT FROM AUTHOR]

Urban parks have significant cooling effects, which can both mitigate the urban heat is-land effect and are crucial to the sustainable development of the human habitat. Although studies have been conducted to explore the influence of urban park morphology on the cooling effect of parks, they are not sufficiently in depth. Therefore, this paper took 117 urban parks in the central city of Chengdu as the research objects based on the perspective of the quantitative classification of urban park morphology. Then, remote sensing interpretation, spatial statistics, and regression analysis were used, and the four indicators of cooling intensity, cooling distance, cooling area, and cooling efficiency of urban parks were integrated to explore the cooling effect of the different morphological types of urban parks. The results show that (1) urban parks in Chengdu could be divided into five categories, among which the cooling effect of round parks was the best, and the cooling efficiency was 0.7. (2) In terms of park cooling area, urban parks' area and perimeter thresholds were 30 ha and 4000 m, respectively. (3) When the area and perimeter of urban parks reached 70 ha and 3000 m, respectively, the increase in the cooling distance slowed down. (4) The cooling efficiency of the park was best when the shape index (indicating the complexity of the park boundaries) of the urban park was 2.8. The results of the study provide theoretical support for the intensive use of urban park green space and help the construction and promotion of a beautiful and livable park city in Chengdu. [ABSTRACT FROM AUTHOR]

In China, traditional food is a significant element of culture that affects human behaviors. The point of interest (POI) of traditional food restaurants' location and their volatile organic compounds (VOCs) emissions affect the urban ecology. Rather than examine potential urban development patch (PUDP) based on land use data, the perspective of this paper is to examine the PUDP, air quality, and food culture in urban ecology in Chengdu, China. Methods: First, the research identifies three types of PUDP models (open PUDP, landscape PUDP, and conflict PUDP) with the weighted overlay of land use data, then uses machine learning to examine the relationship between PUDP, POI of traditional food restaurant, and VOCs. Results: The study generates three types of PUDP which are open PUDP, landscape PUDP, and conflict PUDP. VOCs and POI of traditional restaurant have a strong correlation, and both have a significant negative correlation with open PUDP. However, the landscape PUDP and conflict PUDP do not show an obvious relationship with food POI and VOCs. Conclusion: The results indicate that the future urban ecology should consider restaurant location, VOCs from restaurants, and their relationship to urban land use data as they have a strong relationship. [ABSTRACT FROM AUTHOR]

With the development of the economy, developing high-technology industries and upgrading traditional industries have become a global focus. The relationship between the development of high-technology and traditional industries has also affected urban expansion. In this paper, a fractional derivative gray Lotka−Volterra model with time delay (FDGLV) is established by introducing fractional derivative and delay factor into the GLV model. The model is solved by using the fractional Adams−Bashforth−Moulton predictor−corrector algorithm. The gray correlation analysis is used to determine the time delay value of the model, and the parameters are optimized by using the whale algorithm. Then, the data of high-technology industry, traditional industry, and urban expansion in Chengdu, Changsha, and Chongqing are collected to verify the effectiveness of the model. Finally, the model is used to analyze the coopetition between industrial upgrading and urban expansion in Wuhan, and predict the development status in the next 5 years. [ABSTRACT FROM AUTHOR]

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Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, we look at differences in travel behavior and location characteristics across income in Chengdu, China at two points of time, 2005 and 2016, using household travel surveys. Specifically, we compare changes over time for different income groups for Chengdu in 2005 and 2016. We find that walking or biking remains the most common mode for all income groups but higher-income households appear to have more choices depending on the proximity of their neighborhood to downtown. We also find that both average local and average regional access have worsened since 2005. Furthermore, it appears that there is less economic diversity within neighborhoods in 2016 when compared to 2005, with more locations appearing to have 40% or more of low-, middle-, or high-income households than in the past. Finally, we find that low-income households and older trip makers are more likely to walk or bike and that high-income households are the most likely to own cars and use motorized modes. Built environment characteristics like mixed land use appear to significantly reduce travel time in 2016 but do not result in higher non-motorized transport mode share. We contribute to existing literature by evaluating changes in the relationship of built environment and travel behavior during a period of rapid urbanization and economic growth in a Chinese city. [ABSTRACT FROM AUTHOR]

Based on the cross-sectional data of 2000 and 2015, this paper quantitatively analyzes several indicators of the Chengdu-Chongqing Urban Agglomeration, including the permanent population, urban population, GDP, and total industrial output value, to explore the overall situation of the spatial development of urban agglomeration at this stage. The study finds that the permanent population and GDP maintain the trend of concentrating to higher-level cities, and the central cities of Chengdu and Chongqing have an obvious status of polarization. The main city of Chongqing is relatively dependent on industry, while the main city of Chengdu is driven by service economy and has a stronger capacity of urban population concentration. Different from the traditional understanding, Chongqing's regional central cities have realized rapid industry-driven growth, and their development is faster than that of Sichuan's prefecture-level cities. Despite of a large outflow of population, county-level units have achieved high growth rate of urban population, and the in-situ urbanization is obvious. The spatial pattern shows an "eastward inclination," in which the development of western Chongqing is the most outstanding, while that of Chengdu Plain and southern Sichuan region with a better basis has slowed down, and the originally backward areas, such as northeastern Chongqing, southeastern Chongqing, and eastern Sichuan, have a prominent development. [ABSTRACT FROM AUTHOR]

Copyright of Geography & Geographic Information Science is the property of Geography & Geo-Information Science Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Street quality plays a crucial role in promoting urban development. There is still no consensus on how to quantify human street quality perception on a large scale or explore the relationship between street quality and street composition elements. This study investigates a new approach for evaluating and comparing street quality perception and accessibility in Shanghai and Chengdu, two megacities with distinct geographic characteristics, using street-view images, deep learning, and space syntax. The result indicates significant differences in street quality perception between Shanghai and Chengdu. In Chengdu, there is a curvilinear distribution of the highest positive perceptions along the riverfront space and a radioactive spatial distribution of the highest negative perceptions along the ring road and main roads. Shanghai displays a fragmented cross-aggregation and polycentric distribution of the streets with the highest positive and negative perceptions. Thus, it is reasonable to hypothesize that street quality perception closely correlates with the urban planning and construction process of streets. Moreover, we used multiple linear regression to explain the relationship between street quality perception and street elements. The results show that buildings in Shanghai and trees, pavement, and grass in Chengdu were positively associated with positive perceptions. Walls in both Shanghai and Chengdu show a consistent positive correlation with negative perceptions and a consistent negative correlation with other positive perceptions, and are most likely to contribute to the perception of low street quality. Ceilings were positively associated with negative perceptions in Shanghai but are not the major street elements in Chengdu, while the grass is the opposite of the above results. Our research can provide a cost-effective and rapid solution for large-scale, highly detailed urban street quality perception assessments to inform human-scale urban planning. [ABSTRACT FROM AUTHOR]

the construction of high-speed railway improves the accessibility of cities along the route and plays a certain role in promoting the economic development of cities. The construction of Chengdu-Chongqing high-speed railway improves the timeliness and accessibility of Chengdu to Chongqing, and plays a certain role in promoting the development of cities along the Neijiang River.This paper mainly analyzes the influence of Chengdu-Chongqing high-speed railway on the economic development of Neijiang city after its completion, and puts forward some targeted suggestions for the development of Neijiang. [ABSTRACT FROM AUTHOR]

In the process of urbanization, various urban problems have become increasingly prominent, and the heat island effect is one of them. The expansion of urban land, the increase in construction intensity and the increase in population make the urban heat island effect even worse. The construction of park cities improves the ecological environment of the city and is considered to have a positive effect on alleviating the heat island effect, but it is not clear whether it has such an effect or not. This article explores whether the construction of Park City can help to improve the urban thermal environment effectively, and also, seek solutions for how to improve the construction of park cities so that the heat island effect can be better mitigated. Landsat8 remote sensing images in 2014 and 2019 were used to estimate the fractional vegetation cover (FVC) and land surface temperature (LST) in the Third Ring Road of Chengdu. Land use data were also introduced into the study to analyze LST changes in different surfaces and FVC.The results indicate that: (1) the area of the heat island zone in the Third Ring Road of Chengdu decreased by 0.91% from 2014 to 2019, and the area of the cold island zone increased by 17.89%; (2) the urban blue-green space is conductive to mitigating the urban heat island effect, in which the water provides the best mitigation, while impervious surface and bare land may aggravate the urban heat island effect; (3) the FVC in the area of the Third Ring Road in Chengdu is on the rise as a whole, and there is a significant negative correlation between FVC and LST (p < 0.01). Based on the above results, this paper shows that Park City construction is beneficial to alleviate the urban heat island effect, and more attention should be paid to blue-green space layout and quality, along with urban ventilation and FVC control. Our results provide useful input for green space planning and the construction of Park City in the future. [ABSTRACT FROM AUTHOR]

In investigating the spatiotemporal patterns and spatial attributes of carbon storage across terrestrial ecosystems, there is a significant focus on improving regional carbon sequestration capabilities. Such endeavors are crucial for balancing land development with ecological preservation and promoting sustainable, low-carbon urban growth. This study employs the integrated InVEST-PLUS model to assess and predict changes in ecosystem carbon storage under various land use scenarios within the Chengdu urban cluster, a vital region in Central and Western China, by 2050. The results indicate the following. (1) A linkage between land use dynamics and ecosystem carbon storage changes: over two decades, a 7.5% decrease in arable land was observed alongside a 12.3% increase in urban areas, leading to an 8.2% net reduction in ecosystem carbon storage, equating to a loss of 1.6 million tons of carbon. (2) Carbon storage variations under four scenarios—natural development (NDS), urban development (UDS), farmland protection (FPS), and ecological protection (EPS)—highlight the impact of differing developmental and conservation policies on Chengdu's carbon reserves. Projections until 2050 suggest a further 5% reduction in carbon storage under NDS without intervention, while EPS could potentially decrease carbon storage loss by 3%, emphasizing the importance of strategic land use planning and policy. This research provides a solid theoretical foundation for exploring the relationship between land use and carbon storage dynamics further. In summary, the findings highlight the necessity of incorporating ecological considerations into urban planning strategies. The InVEST-PLUS model not only sheds light on current challenges but also presents a method for forecasting and mitigating urbanization effects on ecosystem services, thus supporting sustainable development goals. [ABSTRACT FROM AUTHOR]

Although urban growth boundaries (UGBs) have been employed as a planning tool in certain Western cities for decades, they have recently been adopted in Chinese cities to address urban sprawl. However, the effectiveness of UGBs in different types of Chinese cities, particularly those on flatlands versus mountains, has not been studied. This study aimed to compare the efficacy of UGBs in a city on flatlands (Chengdu, China) and a mountainous city (Chongqing, China). We used a deep learning architecture (U-Net) to project urban expansions in 2035 with the presence/absence of UGBs and landscape metrics to evaluate UGBs' effectiveness in mitigating urban sprawl. We found significant differences in historical urban expansion between Chengdu and Chongqing from 1992 to 2019. Chengdu experienced spillover sprawl under a monocentric-dominated urban form, while Chongqing witnessed leapfrog and piece-mall sprawl under a polycentric form. Despite the differences in UGBs designation, the simulations demonstrated that UGBs could mitigate urban sprawl in both cities in 2035, with Chengdu exhibiting more pronounced effectiveness. Notably, UGBs were more effective in controlling spillover sprawl in Chengdu, whereas they could effectively reduce leapfrog sprawl in Chongqing. However, UGBs were constrained by strict top-down land quotas, limiting their potential. These findings suggested that implementing UGBs should adopt differentiated goals and strategies for different types of cities. [ABSTRACT FROM AUTHOR]

To measure and present urban size urban spatial forms, in solving problems in the rapid urbanization of China, urban territorial scope identification is essential. Although current commonly used methods can quantitatively identify urban territorial scopes to a certain extent, the results are displayed using a continuous and closed curve with medium- and low-resolution images. This makes the acquisition and interpretation of data challenging. In this paper, by extracting discretely distributed urban settlements, road intersections in OpenStreetMap (OSM), electronic maps, and urban expansion curve based on fractal thoughts have been used to present urban territorial scope and spatial form. Guangzhou, Chengdu, Nanjing, and Shijiazhuang cities were chosen as the identification targets. The results showed that the distance threshold corresponding to the principal curvature point of the urban expansion curve plays a vital role in the extraction of urban settlements. Moreover, from the analysis, the optimal distance thresholds of urban settlements in Guangzhou, Chengdu, Nanjing, and Shijiazhuang were 132 m, 204 m, 157 m, and 124 m, respectively, and the corresponding areas of urban territorial scopes were 1099.36 km2, 1076.78 km2, 803.07 km2, and 353.62 km2, respectively. These metrics are consistent with those for the built-up areas. [ABSTRACT FROM AUTHOR]

Sustainable urban renewal is an important approach to achieving high-quality urban development. The elements of megacities are diverse, and their structures are complex. It is critical to carry out the scientific classification of grassroots governance units based on the concept and needs of urban renewal to promote targeted sustainability evaluation and achieve the precise application of renewal design and planning. This study takes the jurisdiction of Chengdu City as an example and constructs a hierarchical dimension composite classification. For this classification, 128 grassroots governance units are divided into nine types, according to their obvious spatial differences. Based on the properties of these types, suggestions for evaluating and implementing urban renewal are proposed: (1) high-density central areas generally face the dilemma of complex and rigid needs and administrative weaknesses, so the development of public participatory governance is an urgent issue; (2) in transitional suburban zones, areas on and between the development axes are significantly different, indicating that extra attention should be paid to the fairness of the renewal of semi-urbanized areas; (3) outer areas are generally marginalized in urban renewal processes and destructive redevelopment behaviors should be avoided. [ABSTRACT FROM AUTHOR]

• From the "Production-Living-Ecological" perspective, the Tapio decoupling model is used to measure decoupling relationship between EG and WC. • The causal chain of EG and WC is decomposed to explore internal causes. • The decoupling performance in Chongqing and Chengdu has been improving for the period of 2003 - 2019. • Population growth has a greater impact on the decoupling index of EG and WC. • Policy suggestions to achieve sustainable urban economic development and water consumption are recommended. Decoupling economic growth (EG) from water consumption (WC) is essential for the development of sustainable urban areas. To study the relationship between EG and WC of Cheng-Yu Dual-City Economic Circle from a "production-living-ecological" perspective, this paper measures the decoupling relationship between WC and GDP of Chongqing and Chengdu from 2003 to 2019 based on the Tapio decoupling model. By introducing population and industrial growth, the causal-chain decomposition model is then used to decompose the decoupling index into three factors. We found that the relationship between EG and WC in Chongqing and Chengdu decoupled weakly and strongly, which means that there is a trend of healthy and sustainable development. The decoupling relationship of production water is similar to that of the total water consumption, while the production water and the ecological water use are quite different from the total water consumption. For its driving influencing factors, population growth has a greater impact on the decoupling index of EG and WC. Drawing on the above findings of present paper, corresponding development suggestions are proposed to facilitate the health and sustainable development of the Cheng-Yu Dual-City Economic Circle. [ABSTRACT FROM AUTHOR]

The majority of studies on Chinese urbanization have been focused on coastal areas, with little attention given to urban centers in the west. Western provinces, however, will unquestionably undergo significant urban change in the future as a result of the 'Go West' policy initiated in the 1990s. In this paper the authors examine the relationship between drivers of urban growth and land- use outcomes in Chengdu, capital of the western province of Sichuan, China. In the first part of this research, remotely sensed data are used to map changes in land cover in the greater Chengdu area and to investigate the spatial distribution of development with use of landscape metrics along seven urban-to-rural transects identified as key corridors of growth. Results indicate that the urbanized area increased by more than 350% between 1978 and 2002 in three distinct spatial trends: (a) near the urban fringe in all directions prior to 1990, (b) along transportation corridors, ring roads, and near satellite cities after 1990, and, finally, (c) infilling in southern and western areas (connecting satellite cities to the urban core) in the late 1990s. In the second part of this paper the authors connect patterns of growth with economic, land, and housing market reforms, which are explored in the context of urban planning initiatives. The results reveal that, physically, Chengdu is following trends witnessed in coastal cities of China, although the importance of various land-use drivers differs from that in the east (for example, in the low level of foreign direct investment to date). The information provided by the land-use analysis ultimately helped tailor policies and plans for better land management and reduced fragmentation of new development in the municipality. [ABSTRACT FROM AUTHOR]

Rapid urbanization has brought along with it many environmental and social problems such as ecosystem damage and traffic congestion. Therefore, forecasting the trend of urban expansion and providing a reasonable urban planning basis for government departments have become the focus of researchers. An artificial neural network (ANN) can be used to consider spatial nonstationarity when obtaining the changing characteristics of urban land types. Therefore, in this study, we use cellular automata (CA) based on ANN (ANN-CA) to simulate and forecast urban expansion and discuss the parameter sensitivity of the model in detail. In addition, we propose a new Urban Expansion Early Warning Indicator system to warn about the deterioration of future land distribution patterns. Chengdu is selected as the study area, and the study period is from 2000 to 2020. The results showed the following: (1) The best accuracy was achieved when the neighborhood size is 7 × 7 and the number of model iterations is 250, and overall accuracy (OA), Kappa coefficient, and figure of merit (FOM) are 91.47%, 0.855, and 0.354, respectively; (2) ANN-CA is more suitable for predicting the urban expansion of Chengdu than CA based on logistic regression (LR-CA) and CA based on decision tree (DT-CA). Compared with the worst performance model, the score of OA increased by 6.23%, that of kappa increased by 0.062, and that of FOM increased by 0.056. (3) According to the current development trend, artificial built-up areas will increase substantially. The comprehensive evaluation results of the morphology effect, ecological effect, and intensity effect of urban expansion predict severe early warning for Jinniu District, Qingyang District, and Wuhou District by 2030. [ABSTRACT FROM AUTHOR]

The urbanization of China is changing from incremental growth to urban intensification, and urban compactness is a significant attribute for measuring the intensified degree of regional space and societal frameworks. We carefully outline the inadequacies of compactness measuring methodologies and associated research, and argue that compact cities and metro systems contribute to urban sustainable development in tandem. Thereby, this paper investigated 27 strategic region of metro stations on Chengdu Metro Line 1 and proposed a novel urban compactness model in three-dimensions. The result demonstrates that the old urban area before the development of the metro system and the new town thereafter have extreme compactness outcomes, resulting in significant contrasts in morphology and intensification indices. This study investigates the correlation and interaction processes among compactness, morphology, and intensive multiple variables in order to give theoretical and practical support for the intensification design of these two regions in Chengdu. [ABSTRACT FROM AUTHOR]

The two prerequisites for monitoring SDG11.A "support positive economic, social and environmental links between urban, peri-urban and rural areas by strengthening national and regional development planning" are the classification of the urban–rural continuum and the extraction of spatial links. However, the complexity and diversity of urban patch distribution make it difficult to achieve a global rapid assessment. Based on the self-developed high-resolution global impervious surface area 2021 (Hi-GISA 2021) product, this study combined the complex network with remote sensing technology to propose a new method to delineate and evaluate the pattern and inner spatial links of the urban–rural continuum for five typical urban agglomerations in China, including the Beijing–Tianjin–Hebei urban agglomeration (BTHUA), the Yangtze River Delta urban agglomeration (YRDUA), the Greater Bay Area (GBAUA), the Chengdu–Chongqing urban agglomeration (CYUA), and the Middle Reaches of Yangtze River urban agglomeration (MRYRUA). The research results are in good agreement with Chinese government documents. First, the five urban agglomerations are all small-world networks with a low degree of overall polycentricity, and the urbanization degrees of GBAUA and YRDUA are higher than BTHUA, CYUA, and MRYRUA. Second, the imbalanced development of YRDUA is higher than the other regions, and the siphon effects of BTHUA and MRYRUA are more significant than YRDUA, CYUA, and GBAUA. Third, some multi-centers show significant siphon effects. The urbanization degree is highly correlated with the urbanization potential but not positively correlated with the degree of balanced development. The results can provide data, methods, and technical support for monitoring and evaluating SDG11.A. [ABSTRACT FROM AUTHOR]

Urbanization affects air pollutants via urban expansion and emission growth, thereby inevitably changing the health risks involved with air pollutants. However, the health risks related to urbanization are rarely estimated, especially for cities with complex terrain. In this study, a highly urbanized city with severe air pollution and complex terrain (Chengdu) is selected to explore this issue. The effects of urban expansion are further compared with emission growth because air quality management is usually achieved by regulating anthropogenic emissions. Air pollution in Chengdu was mainly caused by PM 2.5 and O 3 from 2015 to 2021. PM 2.5 pollution tended to appear in cold months (November to February) owing to the blocking of air and the stable atmospheric layer, whereas O 3 pollution was likely to occur in warm months (April to August) that experience high-temperature and strong-sunlight conditions and are dominated by high-pressure systems. From 2015 to 2021, the 7-year annual average of premature mortality from all non-accidental causes (ANACs) due to PM 2.5 and O 3 was 9386 (95 % confidence interval (CI) of 6542–11 726) and 8506 (95 % CI of 4817–11 882), respectively. Based on the characteristics of PM 2.5 and O 3 , six numerical experiments were conducted to investigate the impacts of urban expansion and emission growth on the health risks related to air pollutants. The results show that urban land use led to an increase in the air temperature and boundary layer height compared with cropland, which was conducive to the diffusion of PM 2.5. Thus, the monthly average surface PM 2.5 concentrations decreased by 10.8 µ g m -3 (7.6 %) in January. However, the monthly average daily maximum 8 h average (MDA8) O 3 concentrations increased by 10.6 µ g m -3 (6.0 %) in July owing to the stronger photochemical production and better vertical mixing during daytime. In this case, premature mortality from ANACs due to PM 2.5 decreased by 171 (95 % CI of 129–200, or about 6.9 %) in January, and that due to O 3 increased by 203 (95 % CI of 122–268, or about 9.5 %) in July. As for the effects of emission growth, the monthly average PM 2.5 and MDA8 O 3 concentrations increased by 23.9 (16.8 %) and 4.8 µ g m -3 (2.7 %), respectively, when anthropogenic emissions were taken into account. Premature mortality from ANACs due to PM 2.5 and O 3 then increased by 388 (95 % CI of 291–456, or about 15.7 %) and 87 (95 % CI of 54–112, or about 4.1 %), respectively. From a health risk perspective, the effects of urban land use on the health risks related to PM 2.5 are about half that of anthropogenic emissions, whereas the effects of urban land use on the health risks related to O 3 can be 2 times that of anthropogenic emissions. This emphasizes that, in addition to regulating anthropogenic emissions, urban planning is also important for urban air quality, especially for secondary pollutants like O 3. [ABSTRACT FROM AUTHOR]

Natural hazards and urbanization put enormous pressure on cities and affect their sustainable development. Against the backdrop of the increasingly prominent urban disease, a comprehensive urban vulnerability assessment has a positive effect on improving the quality of urbanization. In this study, prefecture-level cities in Southwest China were taken as the study area, and their vulnerability was studied dynamically from 2010 to 2019. The four major systems were integrated, and a comprehensive vulnerability evaluation index system was constructed. Game theory and TOPSIS were combined to minimize the impact of subjective factors on the results. The results indicate that the overall vulnerability of Southwest China shows an irregular downward trend and strong spatial heterogeneity. There are 5 cities with very high vulnerability and 1 with very low vulnerability in 2010, accounting for 15.15% and 3.03% of the total number of cities, respectively. In contrast, the results for 2019 are the opposite, with 1 city with very high vulnerability and 5 cities with very low vulnerability. The better the economic situation, the lower the urban vulnerability. And there is a non-strictly negative correlation between urban vulnerability and urban size. When the difference in size between two cities is large enough, the vulnerability of the larger city is significantly lower. Leading development cities such as Chengdu and Chongqing have low vulnerability, while high vulnerability is mainly distributed in cities with poor infrastructure. On the basis of results, the research can be regarded as reference for urban management and coordinated development. [ABSTRACT FROM AUTHOR]

Mega sports events play an important role in the development of the host city. This study examined the relationship between event prestige, city image, place attachment, and event involvement intention of the host community. Data were obtained using questionnaires distributed to college students in Chengdu, China 2022, when it was the host of the World University Games. The results show that the event's prestige as perceived by college students had a significant positive impact on the intention to participate in the event, and the event's prestige had a significant positive impact on the image of the city but had no effect on the place attachment of college students. City image and place attachment has a chain mediating effect between the event prestige and the participation intention. Moreover, hosting an event can form a positive image of the host city, thus further enhancing the place attachment of college students, and providing talent protection for urban development. The implications of these findings for the event's organization strategies as well as future research directions are discussed. [ABSTRACT FROM AUTHOR]

Cultivated land is the principal land source for urban expansion. Recent large-scale urban expansion through the occupation of cultivated land has influenced regional food security and the realization of sustainable development goals. Based on data regarding the cultivated land occupied for urban construction in the Chengdu metropolitan area from 2000 to 2018, the spatio-temporal evolution of cultivated land occupied by urban expansion was analysed using the contribution index. Based on a model comparison, the geographically weighted regression (GWR) model was used to explore the spatio-temporal pattern and evolution path of significant driving factors. The results demonstrate that (1) the total area of cultivated land occupied by urban expansion from 2000 to 2018 was 470.528 km2 and mainly concentrated in the main urban area of Chengdu City and its surrounding districts and counties. The K value continued to decline from 93.23 to 37.48, indicating that the contribution of cultivated land in urban expansion is decreasing. (2) The GWR model, with a better fitting effect, demonstrates that the significant factors that influence the cultivated land occupied by urban expansion in the study area gradually shift from population aggregation factors to food safety and the proportion of non-farming population. (3) The evolution type of the driving force is mainly dominated by continuous change, and there is significant spatial heterogeneity in the evolution path. The population density → proportion of non-farm population → grain yield → comprehensive and proportion of cultivated land → per capita fixed asset investment → comprehensive → proportion of non-farm population were typical pathways. (4) Realizing the coordination between urban system structural optimization and cultivated land protection policies in the Chengdu metropolitan area is an important way to guarantee regional food and ecological security and promote the green and high-quality development of the metropolitan area. This study can promote coordination between urban expansion and cultivated land protection in metropolitan areas and provide a reference basis for sustainable economic and social development. [ABSTRACT FROM AUTHOR]

This study investigates the impact and transmission mechanism of foreign direct investment (FDI) inflows on the economic growth of city clusters. Via theoretical analysis, a spatial Durbin model (SDM) and mediating effect model are applied based on panel data of the three major city clusters in the Yangtze River Economic Belt (YREB) from 1997 to 2018. The results reveal the following: (1) FDI inflows promote the economic growth of city clusters in the YREB, but the degrees of impacts on the three city clusters are different; (2) the spatial effects of FDI inflows differ across city clusters; the effects are negative in city clusters of the Yangtze River Delta and the Yangtze River Middle Reaches, and positive in the Chengdu-Chongqing city cluster; (3) urbanization and industrial structure upgrading are two important mechanisms by which FDI inflows promote the economic growth of city clusters. However, there are differences among the three major city clusters; the intermediary effect of urbanization is more significant in city clusters of Chengdu-Chongqing and the Yangtze River Middle Reaches, while the intermediary effect of industrial structure upgrading is more significant in the Yangtze River Delta and Chengdu-Chongqing city clusters. Policy implications are proposed accordingly. [ABSTRACT FROM AUTHOR]

Chengdu, located at the western edge of the Sichuan Basin, is the provincial capital of Sichuan Province. The fertile and well-watered basin has given the city a long and splendid history, which has left significant and lasting imprints on its urban form, landscape and cultural life. In the planned economy period, Chengdu serviced as the economic, cultural, logistical and technological center for southwest China, and built a competitive and broad industrial base which now helps the city maintain its leading position in the region. In 2007, Chengdu was assigned as one of two pioneer cities in coordinating urban–rural development. This paper introduces the urban development of Chengdu as a historical city, summarizes the city’s economic growth, urban spatial transformation and infrastructure construction as a major city in western China, and discusses its recent efforts in coordinating urban–rural development as a pioneering city in China. [ABSTRACT FROM AUTHOR]

The construction of urban rail transit (URT) guides and promotes urban development. Different URT line construction schedule, including construction sequence (priority order of line construction) and construction timing (when to build), will have different effects on urban traffic and development. Therefore, the planning of construction schedule is an important part of URT network planning. At present, the determination of construction schedule is mainly based on qualitative analysis methods (i.e., experience, comparisons with other cities, and expert opinion) in engineering practice. In this study, based on an analysis of the main factors affecting the construction sequence and the construction timing data of existing URT lines, a quantitative double-level model of a construction schedule is proposed. The model consists of construction sequence and construction timing sub-models. The construction sequence sub-model employs an improved Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) with Rough Set method; the construction timing sub-model takes the results of the construction sequence model and the factors associated with urban development characteristics into account and presents an improved Logistic-β method. The model is verified using the Chengdu rail transit network as the case study. The results of the study show that the double-level calculation model could provide quantitative theoretical support for the construction schedule planning of URT network. [ABSTRACT FROM AUTHOR]

In the context of uneven development studies of China, urban built-up area changes are the index of the impact of power, as the local government is the only party that is able to acquire agricultural land and convert it to construction urban land. Existing studies generally use statistical data to describe the built-up area changes and struggle to meet the requirement of an updated and inexpensive monitoring of uneven development, especially for western cities with tight budgets. Open access NPP-VIIRS (Suomi National Polar-orbiting Partnership Visible Infrared Imaging Radiometer Suite), NDVI (Normalized Difference Vegetation Index), and nighttime LST (Land Surface Temperature) data ranging from 2015 to 2019 were analyzed with a stratified SVM (Support Vector Machine) method in this study to track urban built-up area changes in Chengdu, one of the biggest cities in Western China. The SDE (Standard Deviation Ellipse) and Moran's I were then applied to evaluate the spatial variations of the built-up area changes. It was revealed that the spatial evolution of built-up area change in Chengdu over the period 2015–2019 demonstrated a "northwest-southeast" spatial expansion pattern, and the change distance in the center of gravity in 2018 and 2019 was greater than that from 2015 to 2017, which reflected the faster uneven development in 2018 and 2019 in Chengdu. The results were verified with finer resolution Landsat-8 OLI images; the high OA (all larger than 92%) and KAPPA (all larger than 0.6) values showed the accuracy of the method. The methodology proposed in this study offers a practical way for cities with tight budgets to monitor uneven development, and this study suggests a further adaption using higher-resolution remote sensing images and field experiments. [ABSTRACT FROM AUTHOR]

Located in the mountainous area of southwest China, the Chengdu–Chongqing urban agglomeration (CCUA) has been rapidly urbanized in the last 4 decades, which has led to a 3-fold urban area expansion, thereby affecting the weather and climate. To investigate the urbanization effects on the thermal environment in the CCUA under complex terrain, we conducted simulations using the advanced Weather Research and Forecasting (WRF V4.1.5) model together with combined land use scenarios and terrain conditions. We observed that the WRF model reproduces the general synoptic summer weather pattern, particularly for the thermal environment. It was shown that the expansion of the urban area changed the underlying surface's thermal properties, leading to the urban heat island effect, enhanced further by the complex terrain. The simulation with the future scenario shows that the implementation of idealized measures including returning farmland to forests and expanding rivers and lakes can reduce the urban heat island effect and regulate the urban ecosystem. Therefore, urban planning policy has the potential to provide feasible suggestions to best manage the thermal environment of the future city toward improving the livelihood of the people in the environment. [ABSTRACT FROM AUTHOR]

Urban vitality is a key indicator for measuring urban development. This topic has been trending in urban planning and sustainable development, and significant progress has been made in measuring single indicators of urban vitality based on parcel or block units. With the continuous development of smart sensing technology, multisource urban data are becoming increasingly abundant. The application of such data to measure the multidimensional urban vitality of street space, reflecting multiple functions of an urban space, can significantly improve the accuracy of urban vitality analyses and promote the construction of people-oriented healthy cities. In this study, streets were taken as the analysis unit, and multisource data such as the trajectories of taxies and shared bicycles, user reviews and cultural facility points of interest (POIs) in Chengdu, a city in southwestern China, were used to identify spatial patterns of urban vitality on streets across social, economic and cultural dimensions. The correlation between the built environment factors and the multidimensional urban vitality on the street was analyzed using a multiple regression model. The spatial distribution of the different dimensions of urban vitality of the street space in Chengdu varies to a certain extent. It is common for areas with high social vitality to have production and life centers nearby. High economic vitality centers are typically found along busy streets with a high concentration of businesses. Areas with high cultural vitality centers tend to be concentrated on the city's central streets. Land use, transportation, external environment, population and employment are all closely linked to urban vitality on streets. The crowd counting and POI density have the greatest impact on multidimensional urban vitality. The crowd and the level of service facilities profoundly affect social interaction, trade activities and cultural communication. The goodness of fit (R2) of the regression models for social, economic and cultural vitality are 0.590, 0.423 and 0.409, respectively. Using multisource urban data, our findings can help stakeholders better understand the spatial patterns and influencing factors of multidimensional urban vitality on streets and provide sustainable urban planning and development strategies for the future. [ABSTRACT FROM AUTHOR]