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Urban sprawl poses substantial challenges to sustainable urban development, particularly within the context of rapid urbanization as observed in China. Leveraging China’s “Urban Development Boundaries Pilot Projects” from 2003 to 2020 as a quasi-natural experiment, this study employs a difference-in-difference approach to investigate the causal impact of urban growth boundary (UGB) policies on controlling urban sprawl. The findings indicate a restraining effect of UGB on urban sprawl. The urban sprawl index of pilot cities diminished by 0.0447 units relative to non-pilot cities, equating to an approximately 9.18% decline from the pre-policy mean of 0.4862. Heterogeneity analysis reveals that the reduction effect of UGB is more pronounced in southern and eastern cities, as well as cities with a moderate level of market integration. This restraining impact amplifies as the administrative level of the city escalate. We find that the inhibitory effect exhibits a U-shaped trend as population density increases. This paper broadens the analytical lens on urban sprawl and furnishes both theoretical underpinning and empirical substantiation for the appraisal of UGB policy implications. [ABSTRACT FROM AUTHOR]

The implementation of an urban growth boundary (UGB) can effectively control urban sprawl and promote efficient land use, which is crucial for future urban development. However, most of existing studies overlook the reuse of existing idle and inefficient land within the city in the delineation of UGBs. With China's urban construction shifting from incremental development to stock development, this study focuses on Wuhan and presents a set of technical approaches for delineating UGBs with a stock development orientation. First, a built-up area composite index (POI&ISA) is constructed based on point of interest (POI) kernel density analysis and impervious surface index extraction to evaluate constructive levels in 2010 and 2020 and identify the urban vitality zone. Then, we combine the current land use status and control policies to divide the urban spatial development potential into five categories: urban vitality land, urban non-vitality land, other vitality land, other non-vitality land, and restricted development land. Finally, the PLUS model is applied in the analysis of the driving forces of land use change in Wuhan, simulating the UGBs in three stages of incremental development (2020–2030), incremental and stock development (2030–2040), and stock development (2040–2050). Finally, the PLUS model simulation projects the UGB areas to be 436.436 km2, 474.617 km2, and 520.396 km2 for the years 2030, 2040, and 2050, respectively. The predicted timespan of urban development extends up to 30 years, serving as a reliable reference for Wuhan's long-term and near-term planning. [ABSTRACT FROM AUTHOR]

China's unprecedented rapid urbanization has encroached upon ecologically sensitive areas. Since 2013, Wuhan, a central urban hub in China, has adopted Ecological Control Line Planning (ECLP) to regulate urban growth and preserve ecological integrity. This study evaluates how ECLP is implemented in the Wuhan Metropolitan Development Zone (WMDZ), a critical region for harmonizing urban expansion with ecological preservation. The assessment integrates two fundamental aspects—conformity and utilization—with evaluations across spatial and ecological dimensions. This methodology builds a technical framework for rapid identification and detailed analysis of planning effects through LULC statistics and landscape connectivity index monitoring. The findings reveal that the ECLP is spatially conformable and utilizable, successfully curbing urban expansion and channeling development towards the urban growth boundary (UGB) and ecological development area (EDA). However, ECLP has not significantly mitigated the decline in ecological connectivity. Details include the following: (1) The general spatial consistency of the ECLP was 88.53%, with the EDA and ecological baseline area (EBA) achieving 85.18% and 88.98%, respectively. (2) Most of the increase in impervious land within ecological lines originated from agricultural and water areas, with only 7.02 km2 of land transitioning to non-agricultural and non-ecological uses. (3) The integral index of connectivity (IIC) exhibited a more rapid deterioration post-ECLP implementation, suggesting the disruption or degradation of critical connectivity pathways or patches within the ecological network. (4) Core ecological patches experienced significant losses inside and outside the UGB, with losses within the UGB being 2.51 times greater. The findings underscore the importance of ecological connectivity in implementing ecological space protection planning and the need for the flexible governance of areas where protection and development conflicts arise. [ABSTRACT FROM AUTHOR]

With rapid economic development, the size of urban land in China is expanding dramatically. The Urban Growth Boundary (UGB) is an expandable spatial boundary for urban construction in a certain period in order to control the urban sprawl. Reasonable delineation of UGB can inhibit the disorderly spread of urban space and guide the normal development of the city. It is of practical significance for the construction of green urban space. The study utilizes GIS technology to establish a land construction suitability evaluation system for Nankang city, which is experiencing rapid urban expansion, and outlines the preliminary UGB under the future land use simulation (FLUS) model. At the same time, considering the coupled coordination of "Production-Living-Ecological Space", and based on the suitability evaluation, we revised the preliminary UGB by combining the advantages of the patch-generating land use simulation (PLUS) model and the convex hull model to delineate the final UGB. The results show that: 1) the comprehensive score of the evaluation of the suitability of the construction of land from high to low shows the distribution of the center of the city to the surrounding circle type spread, the center of the city has the highest suitability score. The results of convex hull model show that the urban expansion type of Nankang is epitaxial. In the future, the urban expansion will mainly occur in the northern part of the city. The PLUS model predicts an increase of 3359.97 hm2 of construction land in Nankang by 2035, of which 2022.97 hm2 is urban construction land. 2) The FLUS model has a prediction accuracy of 86.3% and delineates a preliminary UGB area of 9215.07 hm2. 3) We used the results of the construction suitability evaluation, PLUS model simulation results, and convex hull model predictions to revise the originally delineated UGB. The final delineated UGB area is 8895.67 hm2 and it is capable of meeting the future development of the study area. The results of the delineation can promote sustainable urban development, and the delineation methodology can provide a reference basis for the preparation of territorial spatial planning. [ABSTRACT FROM AUTHOR]

The delineation of urban growth boundary (UGB) can reasonably guide the direction of urban development and effectively restrain urban sprawl. From the perspective of coordinated development, this paper combined the multi-objective land use suitability evaluation method and the PLUS model to define the rigid UGB of the great Nanchang metropolitan area and the elastic UGB under three scenarios of natural growth, policy constraints and coordinated development. It is found as follows. ➀ The spatial distribution of multi-objective land use suitability presents the characteristics of differences, overlaps and crosses. The overlapping area of the most suitable areas for coordinated development with the most suitable areas of agriculture and the most critical areas of ecological protection has decreased compared with the most suitable areas of urban construction. ➁ The area within rigid UGB is 35 391. 03 km², accounting for 76. 11% of the total area of the study area, which can effectively control the urban expansion of the great Nanchang metropolitan area without breaking through the red line of ecological protection and the bottom line of food security. ➂ The simulation results based on the PLUS model showed that arable land, forest land, grassland and unused land decreased, while water area and construction land increased. The expansion of construction land was the most significant, and urban expansion was effectively constrained under the coordinated development scenario, the elastic UGB under the coordinated development scenario can effectively slow down the occupation of the areas with the highest agricultural or ecological value by urban expansion, and can better optimize the urban landscape pattern. The results are helpful to guide and realize the sustainable development of the great Nanchang metropolitan area, and can also provide reference for the coordinated development of production-living-ecology space in other types of cities. [ABSTRACT FROM AUTHOR]

The implementation of an urban growth boundary (UGB) can effectively control urban sprawl and promote efficient land use, which is crucial for future urban development. However, most of existing studies overlook the reuse of existing idle and inefficient land within the city in the delineation of UGBs. With China’s urban construction shifting from incremental development to stock development, this study focuses on Wuhan and presents a set of technical approaches for delineating UGBs with a stock development orientation. First, a built-up area composite index (POI&ISA) is constructed based on point of interest (POI) kernel density analysis and impervious surface index extraction to evaluate constructive levels in 2010 and 2020 and identify the urban vitality zone. Then, we combine the current land use status and control policies to divide the urban spatial development potential into five categories: urban vitality land, urban non-vitality land, other vitality land, other non-vitality land, and restricted development land. Finally, the PLUS model is applied in the analysis of the driving forces of land use change in Wuhan, simulating the UGBs in three stages of incremental development (2020–2030), incremental and stock development (2030–2040), and stock development (2040–2050). Finally, the PLUS model simulation projects the UGB areas to be 436.436 km2, 474.617 km2, and 520.396 km2 for the years 2030, 2040, and 2050, respectively. The predicted timespan of urban development extends up to 30 years, serving as a reliable reference for Wuhan’s long-term and near-term planning.

China’s unprecedented rapid urbanization has encroached upon ecologically sensitive areas. Since 2013, Wuhan, a central urban hub in China, has adopted Ecological Control Line Planning (ECLP) to regulate urban growth and preserve ecological integrity. This study evaluates how ECLP is implemented in the Wuhan Metropolitan Development Zone (WMDZ), a critical region for harmonizing urban expansion with ecological preservation. The assessment integrates two fundamental aspects—conformity and utilization—with evaluations across spatial and ecological dimensions. This methodology builds a technical framework for rapid identification and detailed analysis of planning effects through LULC statistics and landscape connectivity index monitoring. The findings reveal that the ECLP is spatially conformable and utilizable, successfully curbing urban expansion and channeling development towards the urban growth boundary (UGB) and ecological development area (EDA). However, ECLP has not significantly mitigated the decline in ecological connectivity. Details include the following: (1) The general spatial consistency of the ECLP was 88.53%, with the EDA and ecological baseline area (EBA) achieving 85.18% and 88.98%, respectively. (2) Most of the increase in impervious land within ecological lines originated from agricultural and water areas, with only 7.02 km2 of land transitioning to non-agricultural and non-ecological uses. (3) The integral index of connectivity (IIC) exhibited a more rapid deterioration post-ECLP implementation, suggesting the disruption or degradation of critical connectivity pathways or patches within the ecological network. (4) Core ecological patches experienced significant losses inside and outside the UGB, with losses within the UGB being 2.51 times greater. The findings underscore the importance of ecological connectivity in implementing ecological space protection planning and the need for the flexible governance of areas where protection and development conflicts arise.

The delineation of Urban Growth Boundaries (UGBs) has been effective in curbing urban sprawl and facilitating sustainable urban development. This research employs an interdisciplinary framework that combines landscape architecture, landscape ecology, and GIS, focusing on Harbin—a typical cold-region city. The results are as follows: (1) The land use simulation demonstrated high reliability, achieving an average accuracy of 0.955 and Kappa coefficients exceeding 0.8, validating the projected urban growth boundaries for Harbin’s central urban area by 2035. (2) Distinct urban growth boundaries were evident under different development scenarios. (3) Evaluations showed that development scenarios prioritizing living and production spaces had better landscape integration. (4) All development scenarios were proximate to the existing built-up areas of the central urban region. This study not only confirms the utility of the FLUS model in accurately simulating urban land use changes but also provides actionable insights for urban expansion strategies in Northeast China’s cold-region cities.

The rapid and unprecedented urban growth in Khulna, Bangladesh is making it difficult to implement measures to limit further expansion and define clear administrative boundaries, which is posing a significant threat to the environment and ecological sustainability. Using an Artificial Neural Network (ANN) based urban growth simulation model and landscape metrics, this study aims to evaluate the spatial extent and direction of urban growth and demarcate an Urban Growth Boundary (UGB) by examining the future contiguous expansion of the city for implementing effective land use provision. Utilizing data on biophysical, proximity, neighborhood, and market factors over the past twenty years, the neural network with Markov chain model allocates the land demand for buildup area by 2020 and 2030, concerning twelve explanatory variables. The simulated map of the urban area is further used by landscape metrics to quantify local-level urban patch information viz. landscape pattern, size, aggregation, etc. The compact patch characteristics are mostly found under the Kotwali thana, while, fragmented and unstructured patches are prevailing between urban–rural interfaces. Finally, there has around 95 km2 gap between the existing service provided by KCC and the future demand of Khulna city, creating an imbalance between the supply and demand of urban services. Hence, restricted urban growth would make government investment in service facilities cost-effective and enable planners and decision-makers to intend a feasible trade-off between future land demand and the protection of natural resources.

Urban growth boundaries (UGBs) established by urban planning, are common containment strategies to prevent urban sprawl. We analyze the effectiveness of the UGB strategy in the case of the Metropolitan Region of Santiago de Chile, established by the land use plan in 1994. We describe and quantify the annual growth rate and the development of new built-up areas inside and outside the boundary using GIS. The results show that the expansion of built-up areas is greater outside than inside the UGB (75% vs. 49%), and with a higher annual growth rate outside the UGB (14.6% vs. 2.8%). To achieve greater effectiveness in the strategy, it is necessary to overcome those regulatory mechanisms that allow urbanization beyond the boundary, identified as a factor that promotes expansion, contradicting the objective of the plan. [ABSTRACT FROM AUTHOR]

One of the primary aims of China's territory spatial planning is to control the urban sprawl of local municipals and prevent regional competition and the negative consequences on the environment—which emphasizes the top-down spatial regulation. Indeed, the traditional cellular automaton (CA) model still has limitations when applied to the whole administration area since it may ignore the differences among cities and towns. Thus, this paper proposed a CM-CA (clustering, multi-level logit regression, integrated with cellular automaton) framework to simulate urban growth boundaries for cities and towns simultaneously. The significant novelty of this framework is to integrate several urban growth modes for all cities and towns. We applied our approach to the city of Xi'an, China, and the results showed satisfactory simulation accuracy of a CM-CA model for multiple cities and towns, and the clusters' effects contributed 74% of the land change variance. Our study provides technical support for urban growth boundary delineation in China's spatial planning. [ABSTRACT FROM AUTHOR]

ABSTRACTUrban growth boundaries (UGBs) established by urban planning, are common containment strategies to prevent urban sprawl. We analyze the effectiveness of the UGB strategy in the case of the Metropolitan Region of Santiago de Chile, established by the land use plan in 1994. We describe and quantify the annual growth rate and the development of new built-up areas inside and outside the boundary using GIS. The results show that the expansion of built-up areas is greater outside than inside the UGB (75% vs. 49%), and with a higher annual growth rate outside the UGB (14.6% vs. 2.8%). To achieve greater effectiveness in the strategy, it is necessary to overcome those regulatory mechanisms that allow urbanization beyond the boundary, identified as a factor that promotes expansion, contradicting the objective of the plan.

The Chengdu Metropolitan Area, located on the eastern edge of the world's highest plateau, has experienced a period of integrating urban and rural area development for decades. With rapid urbanization and population growth, the vulnerability and security of the ecological environment have become critical aspects to consider in sustainability. Moreover, the presence of different levels of vitality in the study area has a crucial impact on land-use change. Hence, we propose a growth boundary study based on the theory of urban vitality and ecological networks. We focus on identifying the inefficient urban land and urban development potential land, explore their expansion probabilities to conduct spatial simulations for the next 15 years, and combine the ecological network to form a reasonable spatial pattern. Results showed that the proposed model could simulate the urban growth state more accurately within a certain space scale and integrate different limits and influences to simulate different growth strategies under multiple planning periods. Thus, the proposed model can be an effective decision support tool for the government. [ABSTRACT FROM AUTHOR]

Using the panel data on 93 prefecture-level cities in China from 2005 to 2018, this paper takes the UGB implementation in pilot cities as a quasi-natural experiment and uses the difference in difference model to empirically test the impact and mechanism of urban growth boundary (UGB) on urban industrial air pollution. The results show that the UGB policy has a significant role in reducing urban industrial air pollution. This conclusion remains valid after a series of robustness tests. Furthermore, we found that UGB reduces industrial air pollution through governance effects rather than spillover effects, and the negative impact is dynamic and sustainable. Hence, UGB contributes to the sustainable development of land urbanization in terms of reducing industrial air pollution. This research provides empirical evidence for the sustainable development of land urbanization and green development in China. [ABSTRACT FROM AUTHOR]

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The rapid expansion of cities in tropical regions has triggered a series of problems such as the destruction of rare natural resources and decreases in the environmental resource carrying capacity and ecological security, which seriously threaten the sustainable development of tropical cities. In this study, the city of Sanya, Hainan, China, is taken as an example. A bottom-line ecological security pattern is constructed based on the remote sensing ecological index (RSEI) and the patch-generating land use simulation (PLUS) for urban growth boundary (UGB) delineation. The results show that Sanya has a good ecological background, but the overall ecological quality decreased from 2014 to 2018 due to the expansion of construction in hot spot areas. Under the natural growth scenario, the urban built-up area in Sanya in 2030 will be 73.81% greater than in 2018, mainly occupying a large amount of agricultural and ecological space, and urban expansion will not be effectively suppressed. Delineation of the UGBs combined with the ecological constraints can effectively protect the regional ecological security and control the urban sprawl, which is relatively consistent with the current planning. The results of this study demonstrate that the RSEI-PLUS-based UGB delineation perspective has a high scientific and applicability, and they provide a reference for the coordinated ecological–economic sustainable development of ecologically fragile cities in tropical areas. [ABSTRACT FROM AUTHOR]

The British Green Belt policy effectively controls the growth of urban population and urban expansion, which is a relatively mature tool of territorial space use control. Through content analysis, this paper combs the current management situation, summarizes the development experience of the British green belt. On this basis, suggestions and advices to the urban development boundary in China are given, such as establishing and adjusting the reasonable target of delimiting urban development boundary, formulating relevant legislation and policy guidelines for the demarcation and implementation of urban development boundaries, exploring flexible operation space under rigid control, paying more attention to the ecological attribute of delimiting urban development boundary, and improving the utilization rate of land by conserving and intensive land. [ABSTRACT FROM AUTHOR]

Delimiting the urban growth boundary (UGB) is important for limiting urban sprawl and improving urban sustainability. However, the future UGB delimitation for the entire China is still lacking. Here, we delimited China's UGBs before 2100 under localized shared socioeconomic pathways and 11 urban expansion modes (i.e., spontaneous growth, organic growth, and nine modes integrating both) and evaluated the urban shrinkage pressure and the effects on other land use/cover types and ecosystem services. The results revealed that China's urban land demand was projected to increase first and then decrease under five scenarios before 2100. The extent of UGBs was projected to be 121,199–142,982 km2, 34.14–58.25% higher than the urban area in 2020. As a result of urban population decline, China's urban land demand in 2100 was projected to be 20.83–53.41% lower than the extent of UGBs, implying that China, especially the three provinces of Heilongjiang, Jilin, and Liaoning, will face remarkable urban shrinkage pressure. Future urban expansion in China will mainly occupy cropland, and lead to a simultaneous decline in habitat quality, food production and carbon sequestration. Spontaneous growth will cause greater losses of ecosystem services than organic growth at the national scale, while in some provinces, such a difference will be reversed. To address the urban shrinkage pressure, China needs to control urban area and optimize urban spatial patterns based on UGBs. In addition, the place‐based optimal urban expansion mode is also required to reduce the negative impacts of future urban expansion on ecosystem services and promote sustainable development. Plain Language Summary: Urban expansion has caused a series of ecological and social problems. Therefore, setting urban growth boundaries around cities to limit urban sprawl within such boundaries and reduce its negative impacts has been a critical way for sustainable development. This study delimited China's urban growth boundaries before 2100 under five scenarios of localized shared socioeconomic pathways and 11 urban expansion modes (i.e., spontaneous growth, organic growth, and nine modes integrating both) and evaluated the potential effects of future urban expansion on urban shrinkage pressure, other land use/cover types and ecosystem services. The results showed that China's urban land demand was projected to show an increasing trend followed by a decrease under five scenarios from 2021 to 2100, leading to a nationwide urban shrinkage pressure, and the effects of future urban expansion on ecosystem services varied with urban expansion modes. This study suggests that China, especially the three provinces of Heilongjiang, Jilin, and Liaoning, should take measures to optimize urban spatial patterns and address urban shrinkage pressure, and each province needs to take the place‐based optimal urban expansion mode based on the environmental, social, and economic characteristics to improve urban sustainability. Key Points: The extent of China's urban growth boundary was projected to be 34.14–58.25% higher than the urban area in 2020China's urban land demand in 2100 would be lower than the extent of UGBs, implying China will face remarkable urban shrinkage pressureChina should take effective measures to address the urban shrinkage pressure and reduce the negative impacts from urban expansion [ABSTRACT FROM AUTHOR]

As relics of the legacy of apartheid, the boundaries of cities have expanded exponentially. The notion of the urban edge has therefore been introduced as a planning tool to prevent further sprawl and has become an integral part of spatial planning. Court judgments provide guidelines for the interpretation of the notion, but they do not give direction regarding how it should be implemented. Various factors, both planning and environmental, impact on the success or failure of the implementation of the urban edge. It is also a Spatial Planning and Land Use Management Act 16 of 2013 (SPLUMA) requirement that the drafting of the Spatial Development Framework (SDF) (which may incorporate an urban edge) must consider environmental management instruments. The demarcation and periodic review of an urban edge is an important and complex exercise. The writer submits that an acceptable definition of it is necessary to help resolve the difficulties involved in this process. Section 24 of the Constitution (which is indicative of a compact and sustainable urban environment) requires consideration, as do the interdependence of urban and rural areas. Having a uniform definition of the urban edge would be useful as a guideline to municipalities when demarcating and managing it. As the urban edge may be depicted in a municipal SDF in terms of SPLUMA, and as it is a planning tool, it is recommended that the definition be established by and included in SPLUMA. The definition proposed below incorporates various elements found in existing definitions.

With the rapid and unregulated nature of urban expansion occurring in Chattogram, Bangladesh, the adoption of urban growth restriction mechanisms such as the urban growth boundary (UGB) can provide a robust framework necessary to direct the development of built-up areas in a way that curtails the growth in environmentally sensitive areas of the city. Using a support vector machine (SVM)-based urban growth simulation model, this paper examines the areas of future contiguous expansion of the city to aid in the delineation of the UGB. Utilizing landcover, topographic, and population density data from a variety of sources for the past twenty years, the SVM method with the radial basis function (RBF) kernel is used to develop a model based on fourteen predictor variables. A grid-search is used to tune the hyperparameters and determine the best performance combination of the hyperparameters for the RBF kernel function used in the SVM. The final SVM model using the best performance combination of the hyperparameters indicates a high percentage agreement of 91.79% and a substantial agreement for the Kappa coefficient of 0.7699. The developed SVM simulation model identifies potential areas that are more likely to undergo urban expansion in Chattogram in the next twenty years and provides aids for a stringent and strict delineation of UGB for this region. [ABSTRACT FROM AUTHOR]

Reasonable delineation of the urban growth boundary (UGB) plays a vital role in guiding orderly urban space growth and ensuring urban environmental health. Existing methodologies for UGB delineation have failed to address the significance of ecological security. Therefore, this study presents a framework that couples ecological security pattern (ESP) establishment and construction land expansion (CLE) simulation to delineate the UGB. The proposed framework is applied to the Nanchang Metropolitan Area (NCMA) in southeastern China. First, we established the regional ESP of the NCMA in 2018 based on an improved minimum cumulative resistance model. The areas of low-, medium-, and high-level ESP were 1050.75, 736.42, and 720.59 km2, respectively. Second, we implemented a multi-scenario simulation of CLE in the NCMA in 2025 based on a cellular automata–Markov model. A natural development scenario was superior to urban growth and ecological protection scenarios for social, economic, and ecological development at the regional scale. Accordingly, we delineated the UGB of the NCMA in 2025 with a scale of 687.87 km2, based on dynamic adjustment using the results of ESP establishment and CLE simulation in the natural development scenario. The rationality and scientificity of the proposed framework were verified by comparing the scale and layout of the delineated UGB with the regional planning of Nanchang City. The framework incorporating dynamic adjustment with ESP establishment and multi-scenario CLE simulation provides a useful tool for the delineation of the UGB in similar urbanized cities. Its application is conducive to achieving a win–win outcome of regional ecological security and urban development. [ABSTRACT FROM AUTHOR]

The delineation of the urban growth boundary (UGB) in Dalian has a positive effect on coordinating the contradiction between urban expansion and ecological environment protection. Taking Dalian as an example, based on the evaluation of the 5 ecosystem services (ESs): water yield, soil conservation, carbon sequestration, habitat quality, and ecological leisure, the priority protection areas are selected based on the OWA (ordered weighted averaging) operator, making it an ecological red line protection zone, and the UGB of this city is obtained through the simulation of urban expansion by GeoSOS-FLUS model. The results are as follows. 1) From 2017 to 2019, the annual average values of 5 ESs are moderately low in Dalian, with high values in northeast and low values in southwest. 2) The area of the ecological red line protection zone accounts for 17.49% of the total area of the study area, which is continuously distributed in the northeast and scattered in the southwest of Dalian. 3) While the flexible UGB area accounts for 15.71% of the city area in 2030 and is concentrated in the southwest of the city, the delineation results are consistent with the future development pattern of Dalian, showing a "cluster" development pattern. From the perspective of the tradeoffs of ecosystem services, the rational delineation of urban growth boundary is more conducive to the protection of ecological space, and provides reference for the reasonable management of UGB. [ABSTRACT FROM AUTHOR]

As relics of the legacy of apartheid, the boundaries of cities have expanded exponentially. The notion of the urban edge has therefore been introduced as a planning tool to prevent further sprawl and has become an integral part of spatial planning. Court judgments provide guidelines for the interpretation of the notion, but they do not give direction regarding how it should be implemented. Various factors, both planning and environmental, impact on the success or failure of the implementation of the urban edge. It is also a Spatial Planning and Land Use Management Act 16 of 2013 (SPLUMA) requirement that the drafting of the Spatial Development Framework (SDF) (which may incorporate an urban edge) must consider environmental management instruments. The demarcation and periodic review of an urban edge is an important and complex exercise. The writer submits that an acceptable definition of it is necessary to help resolve the difficulties involved in this process. Section 24 of the Constitution (which is indicative of a compact and sustainable urban environment) requires consideration, as do the interdependence of urban and rural areas. Having a uniform definition of the urban edge would be useful as a guideline to municipalities when demarcating and managing it. As the urban edge may be depicted in a municipal SDF in terms of SPLUMA, and as it is a planning tool, it is recommended that the definition be established by and included in SPLUMA. The definition proposed below incorporates various elements found in existing definitions. [ABSTRACT FROM AUTHOR]

Delineating urban growth boundaries (UGBs) has been proved as an effective approach to constrain urban encroachment and achieve sustainable urban development. However, so far, many studies have not fully taken account of the ecosystem integrity in simulating the urban growth as well as the corresponding UGBs delineation. To bridge this research gap, this paper proposes an ESP-FLUS model to predict the future land use pattern with a comprehensive consideration of ecological protection. In this paper, on the one hand, the ecological security pattern (ESP) is integrated from four ecological aspects (i.e., hydrology, geology, biodiversity, and recreation) and classified into three levels (i.e., basic ESP, intermediate ESP, and optimal ESP). On the other hand, drawing on historical records, random forest coupled with Gini importance are applied to identify the driving factors in shaping the land use variation. Taking the classified ESP as the spatial constraint allied with the identified driving factors into a FLUS model, this paper predicts the urban growth in 2035 in a multi-scenario manner. By analysing the multi-scenario simulation results at both region and district levels, the possible urban planning option under the requirements of local master plans is suggested for sustainable urban development. Against a backdrop of an increasingly severe environmental crisis, this paper develops a new research paradigm to incorporate ESP into UGBs delineation as a way to shed light for urban planners on reaching the balance between eco-environment protection and socio-economic development.

One of the primary aims of China’s territory spatial planning is to control the urban sprawl of local municipals and prevent regional competition and the negative consequences on the environment—which emphasizes the top-down spatial regulation. Indeed, the traditional cellular automaton (CA) model still has limitations when applied to the whole administration area since it may ignore the differences among cities and towns. Thus, this paper proposed a CM-CA (clustering, multi-level logit regression, integrated with cellular automaton) framework to simulate urban growth boundaries for cities and towns simultaneously. The significant novelty of this framework is to integrate several urban growth modes for all cities and towns. We applied our approach to the city of Xi’an, China, and the results showed satisfactory simulation accuracy of a CM-CA model for multiple cities and towns, and the clusters’ effects contributed 74% of the land change variance. Our study provides technical support for urban growth boundary delineation in China’s spatial planning.

This research paper investigates urban sprawl in Thiruvananthapuram Urban Agglomeration (UA) and attempts to delineate Urban Growth Boundary (UGB) for promoting urban sustenance. A 112% rise in the spatial expanse of Thiruvananthapuram UA from 256.22 km2 in 2001 to 542.57 km2 in 2011 might induce urban sprawl in the peripheral areas. The Landsat satellite imagery for the years 1987, 1997, 2007, and 2017 were extracted to examine the spatiotemporal urban growth pattern. Shannon's entropy index was employed to detect urban sprawl in Thiruvananthapuram UA. The UGB delineation process involved future urban growth prediction using the MOLUSCE (Modules for Land Use Change Simulations) plug-in of QGIS software. ANN-MLP (Artificial Neural Network-Multi Layer Perceptron) and CA (Cellular Automata) model was preferred in MOLUSCE to predict future urban growth for the year 2027. Thereafter, hexagons of one square kilometer were used to demarcate the Contiguous built-up Growth Boundary (CGB), and later, sub-administrative units were selected to delineate UGB. The results revealed a rise in the built-up areas from 36.04 km2 in 1987 to 140.69 km2 in 2017. Shannon's entropy index indicated the prevalence of urban sprawl in Thiruvananthapuram UA. The future growth prediction by 2027 exhibited a further rise in built-up areas to 173.31 km2. The total area within CGB is 213.58 km2, while UGB accounted for 355.59 km2, which included 16 sub-administrative units. This study exhibited a unique methodology to delineate the urban growth boundary, which optimizes the future land requirements in developing nations. [ABSTRACT FROM AUTHOR]

Recently, research on sprawl was increasing due to its impacts on the economy, society, and environment. Severalstudies have focused on the application of containment strategies to curb urban sprawl. Urban growth boundaries (UGBs) were among the containment policies adopted to tackle the issue of sprawling cities. This paper set out to undertake an analysis of the factors influencing the performance of the UGB of Riyadh City. A qualitative data analysis using NVivo12 software was adopted. To collect the required data of UGB, semi-structured interviews were conducted with nine experts involved in urban management, Riyadh city development, and other planning agencies. If the application of UGB policy in the western countries has managed to restrain more or less city sprawl, its replication to the case of Riyadh seems to have had some adverse impacts. That is, instead of controlling urban sprawl, it has stimulated it. The reasons may lie in the deficiency of monitoring and evaluation of urban studies, free provision of infrastructure, and lack of coordination between different city planning agencies. Understanding the factors affecting the UGB efficiencywill assist policymakers and urban planners in reducing the spread of scattered and leapfrog residential development, lowering the cost of service supply and promoting infill development

The Chengdu Metropolitan Area, located on the eastern edge of the world’s highest plateau, has experienced a period of integrating urban and rural area development for decades. With rapid urbanization and population growth, the vulnerability and security of the ecological environment have become critical aspects to consider in sustainability. Moreover, the presence of different levels of vitality in the study area has a crucial impact on land-use change. Hence, we propose a growth boundary study based on the theory of urban vitality and ecological networks. We focus on identifying the inefficient urban land and urban development potential land, explore their expansion probabilities to conduct spatial simulations for the next 15 years, and combine the ecological network to form a reasonable spatial pattern. Results showed that the proposed model could simulate the urban growth state more accurately within a certain space scale and integrate different limits and influences to simulate different growth strategies under multiple planning periods. Thus, the proposed model can be an effective decision support tool for the government.

• Land suitability evaluation assessed the suitability of land for urban development. • Intensive development of 3 urban growth boundary scenarios were simulated for 2040. • Landscape pattern of three urban growth scenarios were generated. • Intensive scenario is an ideal development mode. In designing national parks, it is important to balance land use with ecological protection and local socio-economic development. In the past decades, the national park has undergone landscape fragmentation and degradation of ecological functions due to climate change and land use change, especially in national parks with urban areas. Therefore, ecological environmental protection projects should include the assessment of land use when planning urban area development in the national park region. Consequently, we used the Land Suitability Evaluation (LSE) method, with 13 indicators for natural, social and ecological variables, to assess the suitability of the newly created national park for urban land use on the Tibetan Plateau. Combining results of the suitability assessment and the Cellular Automata (CA) method, three urban intensification scenarios were simulated for 2040: (1) unplanned, (2) intensified, and (3) strictly regulated urban growth boundaries (UGBs). The impact of land use on the normalized difference vegetation index (NDVI) was analyzed by remote sensing and GIS tools, and the landscape patterns of the three urban growth scenarios were calculated. Close to 87 % of the area was basically suitable, nearly 13 % was unsuitable, and only 0.06 % (43.4 km2–also included in the basically suitable) was suitable for urban land use. In 2040, the built-up areas are predicted to be 3.38, 2.71 and 2.32 times greater than in 2020 under the unplanned (without considering ecological restrictions), the intensive development (emphasizing the driving force of transportation and tourism on the expansion of built-up areas) and the strict control (maximizing ecological restrictions) scenarios, respectively. An ideal development model was used to balance ecological protection and population growth and economic development. The NDVI analysis revealed that the impact of land use on vegetation cover in the intensive development scenario was ranked as winter pastures > tourist development zones > summer pastures. It is concluded that the intensification scenario, with transport and tourism as the main spatial drivers, is the most desirable for the future coordination of ecological conservation and socio-economic development in the national park. This scenario may alleviate the current environmental pressure of livestock grazing on winter pastures in the national park on the Tibetan Plateau. However, realizing this model requires appropriate engineering design for town development. Future research should assess the impacts of urban growth on the ecological environment, with the aim to achieve sustainable urban development tailored to the various geographic regions. [ABSTRACT FROM AUTHOR]

Abstract Urban sprawl as a low-density, planned or unplanned, unlimited and discontinuous expansion in peripheral areas of the cities is traditionally considered one of the global challenges. Iran has confronted with urban sprawl over the past four decades. The present study aimed to review and compare the relevant literature in developed and developing countries in order to study the drivers of urban sprawl particularly, the most crucial ones in Iran as a developing country in the Middle East. Accordingly, it was found that the processes of urbanization and particularly socio-economic conditions affected urban development areas in Iran. Based on the findings of previous studies, fast urbanization, land policies, and shortcomings in the planning system are the most influential drivers of the urban sprawl in Iran considering that these drivers work with each other instead of working in separated lines. Resumen La expansión urbana como una expansión discontinua, planificada o no planificada, ilimitada y discontinua en áreas periféricas de las ciudades se considera tradicionalmente uno de los desafíos globales. Irán se ha enfrentado a la expansión urbana en las últimas cuatro décadas. El presente estudio ha tenido como objetivo revisar y comparar la literatura relevante en países desarrollados y en desarrollo para estudiar los impulsores de la expansión urbana en particular, como los más importantes en Irán, un país en desarrollo en el Medio Oriente. En consecuencia, se ha encontrado que los procesos de urbanización y, particularmente, las condiciones socioeconómicas afectaron las áreas de desarrollo urbano en Irán. Según los hallazgos de estudios anteriores, la urbanización rápida, las políticas de tierras y las deficiencias en el sistema de planificación son los impulsores más influyentes de la expansión urbana en Irán, considerando que estos impulsores trabajan juntos en lugar de trabajar en líneas separadas.

This paper examines the application of remote sensing, based on the Vegetation-Impervious surface-Soil (V-I-S) model and spatial metrics, in an urban analysis for promoting sustainability and understanding urban growth theory. In order to improve the accuracy of land-cover classification, spectral angle mapping (SAM), spectral mixture analysis (SMA) and band ratioing were applied on satellite images for land-cover classification and comparison of the discrimination efficiency of these techniques. For the SMA, subsets of the Landsat (2, 3, 4, 5, and 7) and ASTER (1, 2, and 3N) images were selected. After endmember extraction and purification, the Bayesian probability of each component was computed and used for spectral unmixing. The classified images of different years were compared to analyze the changes in land-use and spatial pattern using V-I-S, a form of percentage of landscape (PLAND) and annualized urban sprawl index (AUSI). The result indicates that the performance of band ratioing (69% accuracy) is not as good as that of SAM (75%) and SMA (86%) in discriminating between vegetation and agricultural land. It is concluded from the land-use analysis that the growth dynamics substantiate the urban theory of diffusion and coalescence and urban growth management strategies have not been completely successful.

The rapid expansion of cities in tropical regions has triggered a series of problems such as the destruction of rare natural resources and decreases in the environmental resource carrying capacity and ecological security, which seriously threaten the sustainable development of tropical cities. In this study, the city of Sanya, Hainan, China, is taken as an example. A bottom-line ecological security pattern is constructed based on the remote sensing ecological index (RSEI) and the patch-generating land use simulation (PLUS) for urban growth boundary (UGB) delineation. The results show that Sanya has a good ecological background, but the overall ecological quality decreased from 2014 to 2018 due to the expansion of construction in hot spot areas. Under the natural growth scenario, the urban built-up area in Sanya in 2030 will be 73.81% greater than in 2018, mainly occupying a large amount of agricultural and ecological space, and urban expansion will not be effectively suppressed. Delineation of the UGBs combined with the ecological constraints can effectively protect the regional ecological security and control the urban sprawl, which is relatively consistent with the current planning. The results of this study demonstrate that the RSEI-PLUS-based UGB delineation perspective has a high scientific and applicability, and they provide a reference for the coordinated ecological–economic sustainable development of ecologically fragile cities in tropical areas.

Urban growth boundaries (UGBs) are seen as an effective tool to control urban sprawl and promote sustainable urban development. Existing methodologies related to urban boundary delineation focus mainly on increasing land intensification and compact urban development. However, it is not sufficient to focus on optimal urban development, especially in China. The delineation of UGBs should not only take into account the heterogeneity of regional natural resources but also further reconcile urban–ecological conflict. Therefore, this paper proposes a new framework for delineating UGBs in an ecologically sustainable manner. This study first uses the remote sensing ecological index (RSEI) and ecological sensitivity as a basis for ecological constraints (EC). Both the background state of the regional ecology and ecological stress from human activities are considered to be constraints on urban sprawl. These ecological constraints are then combined with a CA-Markov model to simulate future urban development. The framework is applied to the Linxia Hui Autonomous Prefecture, an ecologically fragile region in China, where UGB delineation can be used not only to reconcile ecological and land-use planning conflict but also to ensure sustainable resource development in individual zoning districts. The results suggest that a plan that only considers urban development may have a negative impact on the conservation of natural resources and ecological sustainability. The delineation of UGBs based on the proposed EC-CA-Markov model will thus help guide sustainable urban development. The conceptual and methodological advances in this study are applicable to other ecologically fragile cities and can help in the delineation of UGBs.

Reasonable delineation of the urban growth boundary (UGB) plays a vital role in guiding orderly urban space growth and ensuring urban environmental health. Existing methodologies for UGB delineation have failed to address the significance of ecological security. Therefore, this study presents a framework that couples ecological security pattern (ESP) establishment and construction land expansion (CLE) simulation to delineate the UGB. The proposed framework is applied to the Nanchang Metropolitan Area (NCMA) in southeastern China. First, we established the regional ESP of the NCMA in 2018 based on an improved minimum cumulative resistance model. The areas of low-, medium-, and high-level ESP were 1050.75, 736.42, and 720.59 km2, respectively. Second, we implemented a multi-scenario simulation of CLE in the NCMA in 2025 based on a cellular automata–Markov model. A natural development scenario was superior to urban growth and ecological protection scenarios for social, economic, and ecological development at the regional scale. Accordingly, we delineated the UGB of the NCMA in 2025 with a scale of 687.87 km2, based on dynamic adjustment using the results of ESP establishment and CLE simulation in the natural development scenario. The rationality and scientificity of the proposed framework were verified by comparing the scale and layout of the delineated UGB with the regional planning of Nanchang City. The framework incorporating dynamic adjustment with ESP establishment and multi-scenario CLE simulation provides a useful tool for the delineation of the UGB in similar urbanized cities. Its application is conducive to achieving a win–win outcome of regional ecological security and urban development.

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Copyright of Journal of Ecology & Rural Environment is the property of Journal of Ecology & Rural Environment 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 1979, Bogotá implemented an urban growth boundary with an increase in height limits in central areas. These policies were aimed to protect the surrounding rural areas and consolidate a dense and multi-use city center. Internationally, these policies are criticized arguing that they increase the prices of urban land, which is opposed by the argument that this increase is compensated by raising height limits to avoid higher housing prices. The present study analyzed the height limits and the increase in the price of homes and land, gathering historical prices from different sources and crossing these data with the height regulations of each era. The results show that the increases in the height limits and their use by real estate investment were differentiated and contrary to the intentions of zoning plans, greater in the areas of high social stratum, moderate in the middle stratum, and smaller and even negative for the low stratum. The land in the high stratum sector increased more than seventeen times in value while housing prices remained stable; the valuation was much lower in the lower stratum and housing is now more expensive. [ABSTRACT FROM AUTHOR]

Facing the need to control urban sprawl, many Chinese cities are exploring the use of development-limiting boundaries, such as urban growth boundary (UGB) and urban development boundary (UDB), as required by the central government. Through a key word search of several databases including Web of Science and China National Knowledge Infrastructure, we identified and reviewed hundreds of articles published in academic or professional journals. Our review shows that policy processes discussed in the literature have emphasized the technical aspect with analytical sophistication. We identified three types of approach to UGB and UDB in the literature: the growth-driven, the constraint-oriented, and the hybrid. While urban theories and modeling techniques that originated from Western countries have greatly influenced the analytical process underlying some of these approaches, the UGB/UDB policy debate and explorations were also responsive to China's unique urban and policy conditions. Despite the rich empirical content in the literature, very little research has been grounded in a scientific understanding of China's urban development. Issues such as intergovernmental coordination, policy enforcement, and evaluation were also inadequately addressed in the existing literature. The literature's newness may have been a major factor for these limitations. Our critique of the current literature may inspire new areas of research to generate knowledge that can inform China's continuous policy efforts to combat urban sprawl. [ABSTRACT FROM AUTHOR]

Before the institutional reform of the State Council, the "Three Control Lines" of ecological protection red line, permanent basic farmland and urban development boundary were delineated by different ministries, which resulted in insufficient coordination and overlapping results, and difficulties in implementing management. After the institutional reform of the State Council, the Ministry of Natural Resources is responsible for establishing a spatial planning system. It requires that the three control lines be delineated from top to bottom on the basis of the evaluation of the urban capacity of resources and environment and the suitability of territorial spatial development. This paper summarizes the manifestations and causes of contradictions and conflicts in the delimitation of the three control lines in Shenyang as a pilot city, constructs relationships between the three control lines and the three spaces of ecology, agriculture and cities, establishes the management system and adjustment rules, and explains the adjustment and optimization practices within the scope of the city. The study found that it is difficult to distinguish the functions of the three control lines overlapped in space, mainly because permanent basic farmland undertakes the mission of restricting urban spatial spread, and the index can not be adjusted across administrative regions, which results in some permanent basic farmland having to be arranged in cities; different definitions leading to some urban parks are classified as ecological protection redline; some cultivated land in ecological protection redline was previously classified as permanent basic farmland. The paper puts forward the optimization proposals of three control lines under the background of territorial spatial planning: First, we highlight the characteristics of both the policy line and the technical line, and delimit them from top down and bottom up; second, the country needs to carry on the innovation to the basic farmland adjustment policy and system; third, we will establish a hierarchical management mechanism to properly reserve the flexibility of local administrative power. [ABSTRACT FROM AUTHOR]

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Delimitation of an urban growth boundary (UGB) can effectively curb disorderly urban expansion, optimize urban development space and protect the ecological environment. Eco-environmental sensitivity was evaluated and areas prohibiting construction expansion were extracted by establishing an index system. Point of interest (POI) and microblog data were utilized to analyze the expansion of residential activity space. Urban space expansion potential was calculated using a comprehensive evaluation model, and an urban growth boundary for Jinan in 2020 was delimited combining the predicted urban expansion scale. The results showed that: (1) An evaluation of eco-environmental sensitivity can effectively protect ecological land and provide an ecological basis for urban expansion. Regions with high eco-environmental sensitivities in Jinan are located along the banks of the Yellow River and Xiaoqing River and in southeast mountainous areas, but eco-environmental sensitivities in the central, north and southeast areas are relatively low; (2) The model to evaluate urban residential activity expansion can quantify the spatial distribution of urban residents' activities. Regions with high potential for residential activity space expansion in Jinan are mainly concentrated in the middle of Jinan and most are part of existing built-up areas and surrounding areas; (3) The method that delimits urban growth boundaries based on the coordination of ecology and residential activity space is reasonable. Spatial expansion in Jinan mainly extends towards the east and west wings, and the boundary conforms to the spatial strategy guiding Jinan's development and is consistent with the overall layout in related plans. Considering both ecological protection and the internal forces driving urban expansion, the method of urban growth boundary delimitation used in this study can provide a reference and practical help for studies and management of urban development in the new era. [ABSTRACT FROM AUTHOR]

Highlights • CLUE-S model is used to delimit urban growth boundary (UGB). • Protection and development objectives are innovatively combined in the model. • Village administrative boundaries are used to adjust simulation results. • The method is proven to be effective by a case study in Shenyang, China. • Three scenarios are designed and compared, namely trend development, overall land use planning, and ecological protection. Abstract Urban growth boundaries (UGBs) have been adopted worldwide as a policy tool to control urban sprawl. However, the delineation of recently piloted UGBs in rapidly urbanizing areas of China has methodologically relied mainly on local officials' personal willingness and urban planners' work, thus lacking sufficient scientific evidence and reliable quantitative analysis. To fill this gap, this study simulates the spatial pattern of land use based on the CLUE-S model and land development suitability assessment. The principal advantage of this method lies in the innovative combination and effective balance of the central government's dual requirements of arable land protection and intensive urban development in a rapidly urbanizing country. Moreover, we argue that the village collective—China's rural land owners—should be treated in its entirety in land development policy-making, and we accordingly adjust the simulation results with village administrative boundaries in the UGB delineation to guarantee its effective implementation. Shenyang metropolis in Northeast China is taken as a case study. The results show that urban expansion and farmland shrinkage are two major features of future land use change in Shenyang; the most striking growth of urban land takes place mainly in the central city, especially in the northeast and southwest sectors. Despite slight variations in the growth rate, predominating directions, main sources, and ecological effects, urban development in Shenyang shows quite similar patterns under different development scenarios. Therefore, UGBs delineated on the basis of these scenarios are almost identical in the basic outline, with changes only in marginal areas. This novel method is proven to be effective in delineating UGBs in urbanizing China and has referential significance for urban growth management in other developing countries. [ABSTRACT FROM AUTHOR]

Urban growth boundaries (UGBs) have been applied in many rapid urbanizing areas to alleviate the problems of urban sprawl. Although empirical research has stressed the importance of ecological protection in UGB delineation, existing UGB models lack a component for the assessment of ecologically sensitive areas. To address this problem, we develop an innovative method that is capable of simulating UGB alternatives with economic and ecological constraints. Our method employs a patch-based cellular automaton (i.e. SA-Patch-CA) for simulating future urban growth, constrained by the ecological protection areas produced by an agent-based land allocation optimization model (AgentLA). The delineation of UGBs is also based on the estimated future urban land demand derived from support vector regression (SVR). The proposed method is applied in the Pearl River Delta (PRD), China. Three scenarios are designed to represent different objectives of future industrial transitions. The results indicate that increasing the shares of low energy consumption industries and tertiary industries can effectively reduce urban land demand. By overlapping the simulations, we found that the areal agreement of the simulated UGBs among the three scenarios accounts for approximately 88% of the total area. These areas can then be considered as the primary locations for establishing the UGBs. [ABSTRACT FROM AUTHOR]