Sensitivity evaluation and land-use control of urban ecological corridors: A case study of Shenzhen,China

Constructing an urban ecological corridor system is a major component and critical factor of forming an effective network within an urban ecosystem. Shenzhen, as a highly urbanized area in China, is facing the dual pressures of urban development and ecological conservation. The ecological corridors in Shenzhen are being constantly eroded by urban expansion, resulting in an urgent need to carry out sensitivity evaluations and ecological land management studies. By identifying the spatial range of planned ecological corridors in Shenzhen, we develop a GIS-based ecological sensitivity evaluation model from the perspectives of soil environment, habitat conditions, geological hazards, and human disturbance. Management strategies are proposed with regard to macroscopic protection guidance and microscopic land-use control. The results show that there is little difference in the sensitivity grade of ecological corridors in Shenzhen. With regard to spatial distribution, the sensitivity level is high in the north and low in the south, with moderately sensitive corridors being the dominant type. Meanwhile, we design the land-use control program by taking into account the present management and new land demand and provide the path for implementing the withdrawal, reservation, occupation, and avoidance polices. The results of the sensitivity evaluation objectively reflect the eco-environmental condition of ecological corridors in Shenzhen. The classified and graded protection guidance and space regulatory framework proposed in this study are of significance for guiding the ecological conservation, land use, and sustainable development in urban contexts with similar issues.     

An agent-based learning-embedded model (ABM-learning) for urban land use planning: A case study of residential land growth simulation in Shenzhen,China

A forward-looking urban land use plan is crucial to a city’s sustainability, which requires a deep understanding of human-environment interactions between different domains, and modelling them soundly. One of the key challenges of modelling these interactions is to understand and model how human individuals make and develop their location decisions by learning that then shape urban land-use patterns. To investigate this issue, we have constructed an extended experience-weighted attraction learning model to represent the human agents’ learning when they make location decisions. Consequently, we propose and have developed an agent-based learning-embedded model (ABM-learning) for residential land growth simulation that incorporates a learning model, a decision-making model, a land use conversion model and the constraint of urban land use master plan. The proposed model was used for a simulation of the residential land growth in Shenzhen city, China. By validating the model against empirical data, the results showed that the site-specific accuracy of the model has been improved when embedding learning model. The analysis on the simulation accuracies has proved the argument that modelling individual-level learning matters in the agent’s decision model and the agent-based models. We also applied the model to predict residential land growth in Shenzhen from 2015 to 2035, and the result can be a reference for land-use allocation in detailed planning of Shenzhen. The ABM-learning is applicable to studying the past urban growth trajectory, aiding in the formulation of detailed residential land and public service facility planning and assessing the land use planning effectiveness.     

Monetary valuation of urban underground space: A critical issue for the decision-making of urban underground space development

Urban underground space (UUS) has attracted more and more attention worldwide, but its value, external value particularly, is often ignored or underestimated, which will influence or even change the trade-offs in the decision-making processes of UUS development. This paper employed service replacement cost method (SRCM) to access the value of urban underground space. Since the precise estimate of the value of urban underground space is almost an impossible task, this paper can only provide a crude approximation, in other words, a relative magnitude of the value of urban underground space. The case study of Changzhou City in China manifested that urban underground space provided an important portion of urban economy, which reached up to, but not be limited to, 1.8% of its GDP. This paper should aid in giving urban underground space more weight in urban decision-making process.     

The effects of food sales taxes on household food spending: An application of a censored cluster model

This study proposes a model of household food spending that accounts for zero censoring and can be applied to data collected through a clustered survey design to investigate the impact of food sales taxes on three groups: households who are eligible for and participate in the Supplemental Nutrition Assistance Program (SNAP), households who are eligible but do not participate in the program, and households who are not eligible for the program. We find that SNAP participating households are largely insensitive to grocery taxes and respond to restaurant taxes by shifting more of their food dollars towards at-home foods. Among households who are eligible for SNAP but do not participate in the program, grocery taxes reduce spending on foods purchased for at-home consumption, and thereby increase the amount of the total food budget allocated to away from home foods. This is concerning from a nutrition and health standpoint since away from home foods tend to be more calorie dense and nutritionally poorer than at home foods.     

Identifying the internal structure evolution of urban built-up land sprawl (UBLS) from a composite structure perspective: A case study of the Beijing metropolitan area,China

Differences in the internal composite structure during urban built-up land sprawl (UBLS) will generate different effects, and thus, a city’s spatial structure has important bearings on urban sustainability. This study investigates the spatial and temporal characteristics of the internal structure and allocation relationship of UBLS using multivariate spatial correlation and the Weaver-Tomas composite coefficient based on site data of granted built-up land parcels. Moreover, the composite structure evolution process of UBLS and its driving mechanism are examined in this study. The results reveal that the amount structure of the three types of UBLS (i.e. industrial land sprawl, residential land sprawl and commercial land sprawl) tended to be balanced during the study period. Following the transformation and upgrade of the urban industry structure, the overall composite structure of UBLS ranged from single residential land-use structure (Res.) to industrial-residential land-use structure (Ind.-Res.) In the early period of land marketization, the marketization land granting mechanism caused low spatial correlation between the various types of UBLS and a single composite structure, i.e. Res., single commercial land-use structure (Com.), and residential-commercial land-use structure (Res.-Com.). Subsequently, a dual-driving force including the market economy and government interventions caused a relatively high degree of spatial correlation and a multiple composite structure, i.e. Ind.-Res. and industrial-residential-commercial land-use structure (Ind.-Res.-Com.). However, the evolution characteristics of the composite structure in various regions illustrate some problems, such as the spatial isomorphism phenomenon of the composite structure and the dislocation of urban built-up land allocation. The urban internal built-up land spatial layout pattern is the embodiment of two dominant driving forces, the market and the government, interacting with each other according to natural and socioeconomic conditions. Therefore, we suggest that it is necessary to reform the future urban built-up land granting mechanism based on market guidance, and the composite structure of UBLS should be adjusted according to the regional function. The government should reinforce the macro-control of land-use planning for the dispersed granted land parcels so as to optimize the urban land-use structure.