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Hong W.,Wuhan University | Hong W.,Key Laboratory of Urban Land Resources Monitoring and Simulation | Hong W.,Shenzhen Urban Planning and Land Resource Research Center | Jiang R.,Key Laboratory of Urban Land Resources Monitoring and Simulation | And 5 more authors.
Ecological Indicators | Year: 2016

The extensive use of modeling and technologies such as a geographic information system (GIS) in ecological vulnerability assessment and the recognition of eco-environmentally vulnerable areas from the perspective of spatial positioning provide important complements to urban ecological space management research. This study establishes an ecological vulnerability assessment indicator system containing nine elements and twelve indicators with respect to ecological sensitivity, ecological pressure, and self-resilience. The range of ecologically vulnerable areas in a highly urbanized region is spatially recognized. Management strategies are proposed with regard to institutionalization and marketization. The results show that the ecological vulnerability in Shenzhen is good overall and that most areas are moderately vulnerable; the goal of space management is to enhance ecological function and prevent further expansion of the city as a threat to ecological security. Highly vulnerable areas are mainly distributed in the west and agglomerate with urban functional areas; it is suggested to delimit an ecological red line in this region and implement the most stringent "steel wire" control following the existing ecological protection law in China. Furthermore, this study proposes an ecological preparedness system suited for the particularity of the highly urbanized region in Shenzhen and attempts to introduce marketization into ecological restoration to solve the economic and social plight of ecological reconstruction in highly urbanized regions. The vulnerability assessment results objectively reflect the condition of the regional ecological environment, and the space management policy has implications for ecological protection, resource utilization, and sustainable development in similar cities. © 2016 Elsevier Ltd.


Chen J.,Guangzhou University | Chang K.-T.,Kainan University | Karacsonyi D.,Hungarian Academy of Sciences | Zhang X.,Shenzhen Urban Planning and Land Resource Research Center
Habitat International | Year: 2014

China has been the engine of global urban population growth, with nearly one-third of the global urban population growth realized in China in 2000-2010. This rapid process of urbanization will continue in the coming decades based on media reports, thus raising concerns about urban land expansion and sustainable urban development in China. Using satellite images and government statistics as data sources, this study compared urban land expansion in Shenzhen and Dongguan, two adjacent and sometimes competing cities in the economically most dynamic region of China. Our data show that the two cities were similar in urban land expansion rate and intensity in 1990-2008 but Shenzhen had higher population growth and urban population density than Dongguan during the period, suggesting that Shenzhen had achieved a higher level of sustainable urban development than Dongguan. To explain this difference, we analyzed the driving factors and found that (1) Shenzhen was more successful than Dongguan in transforming its industrial structure to develop more capital- and technology-intensive industries; (2) Shenzhen had much higher total GDP and per capita GDP than Dongguan; (3) Shenzhen had benefited from a number of government policies targeted at the city's economic development; and (4) in addition to geographically adjacent to Hong Kong, Shenzhen had better transportation facilities than Dongguan, including an international airport and three container ports. Through these favorable driving factors, more people had moved into Shenzhen and, in the process, helped transform the city to become more sustainable in its urban development. The findings of this study can help us better understand urbanization in China. © 2014 Elsevier Ltd.


Jiang R.,Shenzhen Urban Planning and Land Resource Research Center | Jiang R.,Key Laboratory of Urban Land Resources Monitoring and Simulation | Wang C.,Shenzhen Urban Planning and Land Resource Research Center | Shen L.,Shenzhen Urban Planning and Land Resource Research Center | Wang P.,Nanjing University of Information Science and Technology
Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery | Year: 2016

As high spatial resolution remotely sensed image be acquired more easily, there is a great potential for obtaining forest inventory automatically and cost-efficiently. A method was proposed to detect the lichee's treetop and delineate tree-crown. The method can be divided into three steps. In the first step, a 3×3 mean filter was utilized to smooth image, and then the image was inverted through subtracting image from the maximum of the filtered image. The second step was individual tree detection, namely treetop detection. The inverted image can be viewed as a topographic surface, the flow direction grid was built and then the depressions grid was extracted. The depressions distributed on roads and constructions were deleted according to the predefined threshold. Watersheds were delineated to obtain the contributing area of depressions viewing depressions as the pour point. For solving that the multiple depressions were erroneously identified within the same crown, the depressions were deleted if the distance to the nearest depression was less than threshold and the mean value of depression in the filtered image was not the maximum in multiple depressions, the watersheds of multiple depressions were merged. The remaining depressions were viewed as the detected treetop. The third step was to delineate the tree-crown by using region growing method. The remaining depressions were used for seed points, crown regions were expanded from depression to surrounding pixels until the difference between the pixel and mean value of depression exceeded the predefined threshold or to the boundary of depression watershed. A 324 pixel×483 pixel Pléiades image with 0.5 m resolution was employed to test the method. A promising agreement between the detected results and manual delineation results was achieved in counting the number of trees and the area of delineating tree crowns. For individual tree detection, the overall accuracy was 87.75%, user's accuracy was 80.69%, producer's accuracy was 96.06%; for individual tree-crow delineation, the overall accuracy was 78.69%, user's accuracy was 71.32%, producer's accuracy was 87.76%. © 2016, Chinese Society of Agricultural Machinery. All right reserved.


Zou H.,Shenzhen Urban Planning and Land Resource Research Center | Yue Y.,Shenzhen University | Li Q.-Q.,Shenzhen University
Transportation Research Record | Year: 2014

The urban traffic state is a self-organized behavior constrained by the road network structure. This study proposed an empirical approach to explain the relationship between the urban traffic state and road network structure from a spatial perspective, which was verified by real link travel speeds derived from floating car data in a typical urban road network. The characteristics of the road network structure were investigated with five quantitative indicators: hierarchy, adjacency, accessibility, efficiency, and density. A regression-kriging model was introduced to explain changes in the traffic state by incorporating the road network structure and the spatial variance caused by the significant spatial characteristics of the state of urban traffic. The model was applied to two designed typical scenarios. The results demonstrated that the model sensitively captured the change of traffic state caused by local changes in the road network structure at historical periods of city development. The process can provide robust initial values for model-driven transportation planning and is useful in practical decision making.


Qian J.,Wuhan University | Qian J.,Shenzhen Urban Planning and Land Resource Research Center | Peng Y.,Wuhan University | Peng Y.,Shenzhen Urban Planning and Land Resource Research Center | And 3 more authors.
Sustainability (Switzerland) | Year: 2016

Shenzhen is a city that is highly representative of China's rapid urbanization process. As the city rapidly expands, there are enormous challenges to the sustainable use of land resources. This paper introduces the evolution of urban land expansion and the sustainable land use policy of the Shenzhen Government since 2005. The policy covers the reduction in rural-to-urban land conversion, the delineation of urban growth boundaries, arable land reclamation and the establishment of farmland protection areas, urban redevelopment, and the investigation and prosecution of illegal construction. This paper considers the aspects of urbanization and land management systems that are unique to China. The current top-down indicative and mandatory mode of control, which relies on the central government, has very limited effects. Good results were achieved in Shenzhen for the following elements: Governmental self-restraint, governmental identity change, and policy innovation. Shenzhen's sustainable land use practices can provide a reference for other cities in China. © 2016 by the authors.


Peng Y.,Wuhan University | Qian J.,Shenzhen Urban Planning and Land Resource Research Center | Ren F.,Wuhan University | Zhang W.,Shenzhen Institute of Building Research Co. | Du Q.,Wuhan University
Sustainability (Switzerland) | Year: 2016

Rapid urbanization and rapid urban growth present great challenges to the sustainable utilization of land resources. This paper discusses the on-going process of construction-to-ecological land conversion (CELC) in terms of three aspects: land use, environmental effects, and system responses. CELC is compared to other current land conversion strategies in China. Taking Shenzhen City as an example, this paper introduces five areas in which CELC has been implemented since 2009, including basic farmland protection zones, mining areas, ecological corridors, inefficient industrial zones, and urban villages. This paper argues that Shenzhen's CELC model can improve the ecological environment, control urban sprawl, and promote sustainable land use and, thus, serve as an example for other cities in China. © 2016 by the authors.


Zhong S.-P.,Dalian University of Technology | Lin J.-S.,Shenzhen Urban Planning and Land Resource Research Center | Deng W.,Nanjing Southeast University
Xitong Gongcheng Lilun yu Shijian/System Engineering Theory and Practice | Year: 2013

In order to study the different travel behaviours of users equipped with advanced traveler information systems (ATIS) and users unequipped with ATIS under uncertainties conditions in both demand and supply sides of a road network due to adverse weather conditions with different rainfall intensities, a path travel time reliability-based traffic assignment model under endogenous equilibrated market penetration and compliance rate of ATIS was established. Those equipped users may not always comply with the advice provided by ATIS. Therefore users are divided into three classes: users with ATIS and in compliance with ATIS advice, users with ATIS but without compliance with ATIS advice, and users without ATIS. Users will consider uncertainty of the path travel time, weather conditions, and ATIS advice in their path choice decisions. Furthermore, the model also considers users' perception errors using a Logit-based stochastic user equilibrium framework. The proposed model is formulated as an equivalent variational inequality problem in terms of path flows. Numerical examples illustrate the efficiency of the proposed model and solution algorithm.

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